Development of a smartphone-based point-of-care molecular diagnostic platform to detect SARS-CoV-2

Nguyen Dan Van Kyung Hee University Graduate School 2022 국내박사

Recently, one of the greatest threats to human life is the global pandemic, specifically the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, which has disastrously impacted people worldwide for more than two years. Within the pandemic, the critical approach for preventing and controlling disease infection is rapid and accurate diagnosis among the community. Generally, there are two diagnostic techniques mainly used for the detection of infectious viruses, specifically molecular diagnostics, and immunological diagnostics. Although immunological diagnostics are simply operated and produce fast detection results within minutes, it expresses low sensitivity, strong dependence on the patient’s immune response, and a significant chance of cross-reactivity. On the contrary, molecular diagnostics with the gold standard approach, mainly reverse transcription-polymerase chain reaction (RT-PCR), can detect SARS-CoV-2 with high sensitivity, specificity, and accuracy even at the early stage of infection. However, the requirement of bulky instruments, skillful technicians, and time-consuming operation limits the on-site application of molecular diagnostics. Therefore, the number of point-of-care (POC) molecular diagnostic devices has been constructed and commercialized for the in-place diagnostics at sites having a high risk of epidemic propagation. However, the biggest drawbacks of these POC platforms are the demand for in-house power and the cost of expensive circuit boards and optical elements. With the continual launch of advanced smartphones and their soaring worldwide use in daily life, there has been a rapidly growing trend for adapting them as sensing tools for molecular diagnostics and medical health care. Since a smartphone comprises numerous metal-oxide-semiconductor (MOS) integrated circuit chips, it can be employed as a sensor for the detection of motion, light intensity, acoustic level, and more. In addition, the perpetual innovation of complementary metal-oxide-semiconductor (CMOS) cameras with larger sensors and multiple lens systems improves the light absorption and the capture capability of a greater dynamic range of tones, resulting in better resolution of the image as well as reduction of the noise background. As a result, it is possible to apply the smartphone’s camera as the fluorescence signal detector instead of using an expensive optical system. The constant hardware development of smartphones also benefits the control and operation of POC molecular diagnostic devices. Based on this knowledge, I constructed the smartphone-based molecular diagnostic devices for detecting foodborne pathogens and SARS-CoV-2. Throughout the studies, the power, camera, and operating systems of the smartphone were employed to operate the capillary electrophoresis, detect fluorescence signals, and control the operation of a molecular diagnostic device. In Chapter 3, the smartphone battery was used to power the capillary electrophoresis assay, a size-based molecule analysis in a micro-capillary containing a 5% gel matrix. Compared to the fluorescence detection method, the electrophoresis technique is a non-real-time testing method, meaning that the amplicons are detected after the completion of the amplification process. Although it takes time for the amplification and gel operation prior to obtaining the result, only the electrophoresis technique can provide single separated molecules which can be further purified for the amplicon sequencing and the molecule characterization. These downstream processes are crucial to determine the viral/bacterial variants as well as mutation determination. However, since gel electrophoresis costs a lot of time and requires many accessories powered by a high voltage, I developed a micro-capillary electrophoresis (µCE) chip powered by the battery of a smartphone for the detection of foodborne pathogens. The 5V output of the smartphone was amplified to 250 V in this study using a boost converter circuit, enabling the CE performance on a chip. Two amplicons (121 bp FliC gene of Escherichia coli and 161 bp InvA gene of Salmonella serovar Typhimurium) were separated using two phases of CE, which included injection and separation. The voltages used in the sample and waste reservoirs during the injection stage were 0 V and 250 V, respectively. The amplicons were filled in the injection channel (6.8 mm in length) in 50 seconds. In the separation channel (17 mm in length), two amplicons were successfully separated in 4 minutes. In order to accurately identify the target peak in the electropherogram, two bracket ladders were added with the amplicon sample. In Chapter 4, more advantages of the smartphone were benefited to construct a miniaturized integrated µCE system for the detection of SARS-CoV-2. By controlling the relay module, the smartphone can orderly power two boost converters and an excited laser for operating two-step µCE. In addition, the CMOS camera of the smartphone with the support of a 520 nm band-pass filter was applied for detecting the fluorescence signal of amplicons amplified with reverse transcription-polymerase chain reaction (RT-PCR). Additionally, a web-based application was created to construct standard capillary electropherograms on smartphones using the recorded fluorescence intensity versus running time. A double-T structure was designed in the µCE chip to accumulate samples in the separation channels during the sample injection step, leading to the better detection of fluorescence signal. Two SARS-CoV-2 genes, the N and S genes, and two bracket ladders were successfully examined in 6 minutes using the integrated smartphone-associated CE system. The total size of the hand-held µCE system was 9.6 cm [Width] × 22 cm [Length] × 15.5 cm [Height], and the weight was ∼1 kg, making it appropriate for POC DNA testing. In Chapter 5, The Raspberry Pi (RPi) and smartphone combo was primarily used to manage and run the entire diagnostic process, from RNA extraction to reverse transcription amplification to fluorescence detection. A Rpi, a Darlington transistor array (ULN2803a), two solenoids valves, a PSD/6 precision syringe pump, a self-built heater system, a Pi camera with a 520 nm band-pass filter, a laser with a divergent lens, a microfluidic chip, and a 3D printed cartridge are all components of an integrated diagnostic platform. The smartphone may manage the on/off status of solenoid valves and the operation of the syringe pump system thanks to a web-based application offered by a node-red programming tool on the Raspberry Pi (RPi). A smartphone was used to control the reverse transcription recombinase polymerase amplification (RT-RPA), as well as the periodic activation of the Pi camera, a 488 nm laser, and the heater's temperature. In this project, I also created a printed cartridge for chemical solution storage and a microfluidic device for RT-RPA-based molecular diagnostics with glass paper and freeze-dried enzymes. A Pi camera was used to take picture of the reaction chambers at intervals of 1 minute during the RT-RPA. The RPi recorded and counted the green pixels in the black-background image that represented the fluorescence signal. The sigmoid function was used to analyze the raw data of fluorescence intensity versus reaction time and produce smooth growth curves. By using our smartphone-controlled diagnostic device, the N gene and S gene of SARS-CoV-2 have been effectively detected at the limit of detection of 10 copies/L within 1 hour, including sample pretreatment. On the smartphone-based POC technology, two real SARS-CoV-2 samples were also successfully analyzed. In Chapter 6, besides the smartphone-based diagnostic platform, I developed a colorimetric quantitative loop-mediated isothermal amplification (LAMP) based on Eriochrome Black T (EBT) dye, which is a complexometric indicator used for detection of calcium, magnesium, or other metal ions. Upon addition to the LAMP mixture, EBT immediately combines with magnesium ions to produce a violet color. During the amplification process, magnesium ions prefer forming stronger combination with the released pyrophosphate to EBT molecule, resulting in the color change of the mixture from violet to sky blue. As a result, the shift of UV-vis absorbance of the reaction mixture from 570 nm to 640 nm was noticed before and after the LAMP reaction. When plotting the ratio values of two absorbances (A640/A570) versus the reaction time, a smooth growth curve was obtained. Then, I amplified serially diluted DNA samples of the biomarker related to acute rejection (AR) of kidney transplanted patients, namely Tim-3-HAVCR2. From the amplification results of diluted samples, a quantitative calibration curve (the threshold time versus the initial copy number of DNA) was established. In Chapter 7, following to the previous research, the quantitative calibration curves of the other five biomarkers related to AR (CD3ɛ, IP-10, CXCL9, PSMB9, C1QB) and a reference gene (18S rRNA) were constructed. According to the results of biomarker quantification performed on urinary cDNA samples of transplanted patients, there is a distinct difference in the concentration of the biomarkers IP-10, Tim-3-HAVCR2, and C1QB between patients with stable grafts and those with acute rejection. These three biomarkers were used to construct the AR prediction model, which had a 93.3 percent accuracy rate in predicting AR of transplanted patients. For the point-of-care (POC) molecular diagnostics for the AR evaluation, I constructed a centrifugal microfluidic platform, in which the RNA extraction from the clinical urinary samples, the quantitative reverse-transcription (RT)-LAMP reaction, and the data analysis based on the AR prediction model could be performed in a serial order. Ten blind clinical samples were successfully analyzed on the POC genetic analyzer, showing 100 % match with the validated qPCR data.

Investigation of neck muscular load among young adults when using smartphone while walking

Hyeseon Han Graduate School of UNIST 2019 국내석사

It is widely understood that frequent and prolonged use of smartphones may cause neck-shoulder pain. However, few studies have reported such risks for neck-shoulder problems associated with the use of a smartphone while walking. Because smartphone use while walking is a very common behavior among smartphone users, investigation of relevant ergonomic risks is also necessary. The aim of this thesis research was to investigate potential ergonomics risk factors among smartphone users, especially when using smartphone while walking. This thesis presents a series of cross-sectional and experimental studies that have independent research questions and discusses the results of them in an integrated form. Study 1 was aimed to objectively assess the angle and duration of head-down of smartphone users during a typical working day via naturalistic data collection. Thirty-one asymptomatic young participants conducted their typical activities while their head tilt angle and smartphone app usage records were collected simultaneously for 8 hours. It was found that study participants spent 125.9 minutes (median usage duration) on their smartphones with significantly larger head-flexion angle (p < 0.05) than when they were not using the phone. Head-down posture greater than 30° was found to be more common when using the phone, while mild flexion within the range of 0° to 20° was more common when they were not using the phone. Study 2 was aimed to quantify the head down position when using a smartphone while walking. Head tilt angle was measured from twenty-eight young smartphone users when conducting one-handed web-browsing and two-handed texting while walking a 60-meter outdoor walkway. Study results showed that the median head tilt angle during texting (38.5°) was significantly greater (p<0.05) than that of web-browsing (31.1°), indicating greater static loads to the neck when texting. Participants walked with significantly less (p < 0.05) variation of the head flexion when texting (5.3°) than when browsing (6.8°), and it implies larger efforts of neck muscles to keep the head steadier for texting. Study 3 was aimed to quantify the myoelectric activation (EMG) of neck extensor muscles, head/trunk movement and eye-smartphone position when using a smartphone while walking. Twenty-one asymptomatic young adults conducted three tasks (no smartphone, one-handed web-browsing, two-handed texting) in the laboratory. The mean normalized EMG (NEMG) of the splenius muscles and the cervical erector spinae muscles were 33.3% to 101.8% greater when web-browsing and texting while walking compared to walking without smartphone. Task effect was found in NEMG of splenius of dominant and non-dominant side, NEMG of cervical erector spinae of non-dominant side, head tilt angle, trunk tilt angle, horizontal viewing distance (p<0.05). Also, angular acceleration RMS of neck flexion when normal-walking was significantly higher than other two task conditions. The findings of these three studies indicated that the smartphone use causes substantially flexed head/neck position of smartphone users, which demands the contraction of neck extensor muscles to maintain the head-down posture. The head-down posture and muscle activation during smartphone use may result in neck muscle fatigue or dynamic and static biomechanical loads on the cervical spine and surrounding tissues. Moreover, head-down position and dual-task cost of smartphone users when they are walking on the road may cause another kind of risks such as fall, collision, stability, and traffic safety. Overall conclusion of this thesis would promote awareness of risks of smartphone use to users and support further researches related to health of smartphone users.

Development of optical biosensing systems by employing smartphone-embedded electronic components

박유민 아주대학교 2016 국내박사

The various smartphone-embedded high technical electronic elements were integrated with biological analytic principle for utilization of simple, low-cost, and user-centered biosensing platform. Currently, the high electronic components such as magnetic sensor, infra-red (IR) sensor, illumination sensor, and charge-coupled (CCD) were contained in the smart IT device. Among them, the illumination sensor and CCD camera were employed to develop the smartphone-based simple optical biosensing system. First, to demonstrate the illumination sensor-based optical biosensing principle, the immunosensing principle was integrated with an immunoblotting assay and a built-in illumination sensor to analyze an osteoarthritis marker. In the various smartphone elements, the illumination sensor sensitively responds to the external light intensity, allowing the application for a simple optical system as a signal transducer. In this study, horseradish peroxidase (HRP)-induced immunoblotting assay was employed to induce the precipitation. The precipitation-induced biosensing channel altered the light intensity according to the analyte which was registered by the illumination sensor. The ambient lights, sunlight and fluorescent, were used as light sources to minimize the composition of the developed optical sensor and increase the usability. Using this, the values of 0–10 ng/mL of urinary C-terminal telopeptide fragment of type II collagen (uCTX-II) were sensitively quantified with good reproducibility. Second, a smartphone-embedded CCD camera was integrated with the paper-based analytical device (PAD) for glucose monitoring. The smartphone-embedded CCD camera has the high technical element, enabling the acquirement of the high-resolution images. To effectively analyze the glucose, a colorimetric glucose assay method using glucose oxidase (GOx) and HRP were employed, implanting on the paper-based analytical device. To confirm the changes in optical signal intensity from the glucose assay, the resulting image was registered by a CCD camera from a smartphone. The experiment was performed in a specifically designed light-tight box mounted with smartphone. By using the developed biosensing system, various concentrations of glucose samples in PBS (0 ~ 20 mM) and human serum (5 ~ 17 mM) were simply and quantitatively analyzed within a few minutes. Third, a simple quantification principle was developed by employing the smartphone-embedded CCD camera with countable microbeads-based biochemical analysis principle for detection of CTX-II. A CCD camera on the smartphone was integrated with the simple prism, filter, and laser for realization of the minimized fluorescence microscope. To detect the biospecific immunoassay for the CTX-II, the quantum-dot (QD) particle having a maximum emission spectrum at 620 nm was employed as an optical signaling probe. The 405 nm laser was installed into the developed biosensing platform as a light source to excite the QD particle. The result images were observed and registered by smartphone-embedded CCD camera, and the immune-specific signal was quantitatively analyzed by counting the number of fluorescent microbeads from the registered images. Using the approach, the sandwich (sCTX-II) and competition (uCTX-II) assays could be immediately quantified on a single chip. The smartphone-based assay would be a promising tool for monitoring of osteoarthritis as a point-of-care testing (POCT) device. Based on these findings, I successfully established a versatile biosensing platform employing the simple utilization of smartphone-embedded high-technical electronics components which can be used for practical disease diagnosis as a POCT device.

An Empirical Study on Customer’s Continuance Intention to Use Smartphone App Store in China

라위의 동국대학교 2013 국내석사

As the fast growth of the mobile communication market, compared with 2010, the market share of Smartphone in China has increased from 12% up to 35% until the first quarter 2012, China has become one of the countries which have the world’s highest Smartphone popularity rate. Accompanying with the popularity of Smartphone, various Smartphone-based mobile services have also been widely accepted by customers in China. Based on the report provided by IPSOS Research in 2012, Smartphone App Store, which usually embedded inside the mobile operating system as a systematic application, has become the most popular platform for customers to search and obtain the applications in China. Meanwhile they also found out that the average number of free applications downloaded from Smartphone App Store for each Smartphone user reached up to 15 and the average number of non-free applications downloaded from Smartphone App Store for each Smartphone user also reached up to 6, both of which indicated China has the world’s second highest rate to obtain applications via Smartphone App Store. There is no doubt that mobile service providers need an efficient method to represent their service quality in order to assess their service quality and the key drivers for service quality improvements. In this study, first of all, a scale for measuring the service quality of Smartphone App Store was proposed. Through exploratory and confirmatory factor analyses, we identified five dimensions of service quality, including content quality, navigation & visual design, system reliability, connection quality and device quality. The final instrument showed adequate reliability and validity. Further, we also examined the relationships among service quality, confirmation, perceived value, customer’s satisfaction, and continuance intention towards Smartphone App Store. The proposed model was strongly supported by the data collected in China. Both service quality and confirmation positively influenced on perceived value and customer’s satisfaction indicating that when Smartphone App Store provides superior service, perceived value and customer’s satisfaction can be enhanced. Perceived value positively influenced customer’s satisfaction. In other words, higher perceived value can lead to higher customer’s satisfaction. Perceived value and customer’s satisfaction directly and positively influenced customer’s intention, where the effect of perceived value was the largest, followed by customer’s satisfaction. Meanwhile, both service quality and confirmation could indirectly influence on customer’s continuance intention through perceived value and customer’s satisfaction. Key words: Smartphone App Store, Service Quality, Content Quality, Navigation & Visual Design, System Reliability, Connection Quality, Device Quality, Confirmation, Perceived Value, Satisfaction, Customer’s Continuance Intention

Are There Different Understandings on Excessive Use of Smartphone between Digital Natives and Digital Immigrants?

Juyeon Ahn Graduate School of UNIST 2014 국내석사

Smartphone is no longer instruments for connecting each other. These days, the people engages in an online activities such as searching in internet, sending email, playing social games, engagement in social networking anytime and anywhere. Indeed, the number of excessive user to smartphone is extremely increased. The rapid growth of excessive smartphone brings to numerous concerns in reality. Despite growing concerns about smartphone addiction, our understanding of this issue remains limited. The purpose of this study is to explore the social understanding of smartphone addiction. In particular, we expect that there is an understanding gap between digital natives and digital immigrants regarding smartphone addiction. For the research objective, transcripts from in-depth interviews of 85 participants were analyzed and were boiled down 24 key topics by content analysis. In the next stage, the topics were classified into central and peripheral factors by core and periphery analysis. And we identified overlapped core topics which have five topics and the others which have five and three topics between two generations. Finally, to compare Digital Natives and Digital Immigrants with different understandings of smartphone addiction, we illustrated the maximum tree, which visualizes social representations. The findings indicate that they have different position or attitude with regard of same situation, smartphone addiction. While Digital Natives perceive the phenomenon of smartphone addiction in the position of an actor; Digital Immigrants understand it from the observer’s perspective. This exploratory study contributes to provide fundamental knowledge about smartphone addiction for future research by initially investigating users’ understandings of smartphone addiction. Also, the findings of the study also enable us to shift attention to perspective aspects of the some social issues that can occur around our lives. In addition, we provide some insight to politicians that they can find the ideas dealing with addictive use of smartphone.

The Relationship between Stress and Smartphone Addiction among Adolescents: The Mediating Effect of Grit

김채윤 서울대학교 대학원 2021 국내석사

The purpose of this study was to investigate the mediating effect of grit on the relationship between stress and smartphone addiction. With the increased usage of smartphones among adolescents, numerous studies have examined smartphone addiction. However, most studies focused on the negative consequences of smartphone addiction, and relatively few studies investigated how adolescents become addicted to smartphones. In fact, no known studies have reported the association between stress, grit, and smartphone addiction among adolescents. Therefore, the present study aimed to explore the relationship between stress, grit, and smartphone addiction among Korean adolescents from age 12 to 16. Particularly, we focused on the mediating effect of grit on the relationship between daily stress and smartphone addiction. Participants were 605 Korean adolescents (mean age = 13.97 years). They completed questionnaires measuring stress, grit, and smartphone addiction. Stress was assessed using the Daily Hassles Scales for Children in Korea developed by Han and Yoo (1995). Grit was measured by the Korean translated version of the Original Grit Scale (Duckworth et al., 2007; Park et al., 2020). Finally, smartphone addiction was measured by using the Smartphone Addiction Proneness Scale for Youth developed by the National Information Society Agency (2011). We analyzed the association of stress, grit, smartphone addiction through Pearson’s correlation analysis. The mediating effect was analyzed by using PROCESS macro version 3.5, and bootstrapping was conducted to test the significance of the mediating effect. The main findings were as follows. First, adolescent stress significantly influenced smartphone addiction. Second, grit had a significant influence on smartphone addiction. Finally, grit partially mediated the relationship between stress and smartphone addiction. In other words, high levels of stress reduced grit, which in turn increased the smartphone addiction proneness. In addition, two factors of grit (consistency of interest and perseverance of effort) both mediated the association between stress and smartphone addiction. These results indicate that adolescent's daily stress may be a potential risk factor for smartphone addiction. Furthermore, by demonstrating the mediating effect of grit on the relationship between stress and smartphone addiction, the present study revealed that stress leads to smartphone addiction through lowered grit. This suggests that high level of grit is an important personal factor that may prevent the path of stress to smartphone addiction. Our study is meaningful in that it is the first study to empirically investigate adolescent's grit in relation to stress and smartphone addiction. Moreover, this study can provide useful information about prevention and intervention strategies for smartphone addiction. Limitations and directions for future studies are discussed. 본 연구의 목적은 청소년의 스트레스와 스마트폰 중독의 관계에서 그릿의 매개효과가 나타나는지 알아보는 것이다. 청소년의 스마트폰 이용이 증가함에 따라 많은 선행 연구들은 스마트폰 중독의 관련 요인에 대해 연구해왔다. 그러나 대부분의 연구는 스마트폰 중독으로 인한 부정적 결과를 중심적으로 다루었으며 청소년들이 어떻게 스마트폰 중독에 이르게 되는지 그 경로에 대한 탐색은 상대적으로 부족한 실정이다. 특히 한국 청소년들을 대상으로 스트레스, 그릿, 그리고 스마트폰 중독의 관계를 탐색한 연구는 전무하다. 따라서 본 연구에서는 12세에서 16세 한국 청소년들을 대상으로 스트레스, 그릿, 스마트폰 중독의 관계를 알아보았다. 더불어 스트레스와 스마트폰 중독의 관계에서 그릿의 매개효과가 나타나는지 알아보았다. 본 연구에는 605명의 한국 청소년들이 참여하였으며 (평균 연령 = 13.97세), 참여자들은 스트레스, 그릿, 스마트폰 중독을 측정하는 설문지를 완료하였다. 스트레스는 한국아동의 일상적 스트레스 척도(Han & Yoo, 1995)를 사용하여 측정하였으며, 그릿은 Original Grit Scale의 번안된 척도(Duckworth et al., 2007; Park et al., 2020)로 측정하였다. 마지막으로, 스마트폰 중독은 한국정보화진흥원(2011)에서 개발한 청소년용 스마트폰 중독 자가진단 척도를 사용하여 측정하였다. 먼저 Pearson의 상관분석을 사용하여 스트레스, 그릿, 스마트폰 중독의 상관관계를 분석하였다. 또한, 스트레스와 스마트폰 중독의 관계에서 그릿의 매개효과가 나타나는지 검증하기 위하여 Hayes(2017)의 PROCESS macro를 실시하였고, 매개효과의 유의성을 검증하기 위해 부트스트래핑(Bootstrapping)을 실시하였다. 본 연구의 주요 결과는 다음과 같다. 첫째, 청소년의 스트레스는 스마트폰 중독에 유의미한 영향을 미쳤다. 둘째, 청소년의 그릿은 스마트폰 중독에 유의미한 영향을 미쳤다. 마지막으로, 그릿은 스트레스와 스마트폰 중독의 관계를 부분 매개하는 것으로 나타났다. 즉, 스트레스가 높을수록, 그릿은 낮아지고, 이는 청소년의 스마트폰 중독 성향을 높이는 경향이 있었다. 게다가, 그릿의 두 하위 요소 (노력 지속과 흥미 유지) 모두 스트레스와 스마트폰 중독의 관계를 부분 매개하였다. 이러한 결과는 청소년의 일상적 스트레스가 스마트폰 중독의 잠재적 위험 요인이 될 수 있다는 것을 의미한다. 더불어 스트레스와 스마트폰 중독의 관계에서 그릿이 매개 역할을 한다는 것을 검증함으로써 본 연구는 스트레스가 스마트폰 중독으로 이어지는 기제를 밝혔으며 그릿이 청소년기 스마트폰 중독 위험성을 완화하는 개인적 요인이 될 수 있다는 것을 밝혔다. 본 연구는 청소년기 그릿을 스트레스, 스마트폰 중독과 연관시켜 탐색한 첫번째 경험적 연구이며 스마트폰 중독의 예방과 개입에 도움을 줄 수 있는 정보를 제공할 수 있다는 점에서 학문적 의의가 있다. 논의에는 이 연구의 한계점과 추후 연구 방향에 대한 제언을 제시하였다.

(An) integrative critical incident approach to quality management in the smartphone market : product, service, and content

오윤선 서울대학교 대학원 2012 국내석사

The explosive growth of the smartphone market and furious competition among global IT (Information Technology) leaders necessitate a better understanding of consumers’ quality perceptions of smartphones, their related services, and contents. In this study, a critical incident approach to quality perception and management is utilized to investigate how the quality of a smartphone device, product-related services, telecommunications services, and application contents influences owner intentions of future purchases. Specifically, critical incidents that smartphone owners may confront are hypothesized to engage in forming their satisfaction level or quality perceptions of smartphones, affecting their likelihood of future purchases with regard to the three major smartphone supply chain parties: the mobile device manufacturer, the telecommunications carrier and the application content provider. The proposed model was empirically examined by regression analyses of 795 smartphone users’ responses. The results can be summarized as follows: Smartphone owners are affected by the critical incidents associated with their smartphones which they experienced during the ownership cycle; the owners’ overall quality perceptions of smartphones are influenced by the critical incidents related to phone device, product-related services, telecommunication services, and application contents; the specific critical incident categories that significantly have an effect on each smartphone supply chain party differ with each other. Additionally, quality management through monitoring and managing critical incidents during the ownership period is verified to applicable in smartphone market in order to enhance quality perceptions of customers, leading to business prosperity as well as better quality design of smartphone products and services. Keywords: Critical Incident; Quality Management; Integrative Approach; Supply Chain Management; Smartphone

The prospective market for smartphone in China rural areas: a view based on technology

Zhao, Chen 서울대학교 대학원 2013 국내석사

We are moving into a technology age that many of us cannot believe could not have imagined even a couple of years ago. Technology develops at such speed that it extends the boundaries that one feels could not be possible. As one of the most important implied results of interdisciplinary research in recent ten years and a landmark of technology innovation, smartphones play an extremely important role today, since they change our life and make breakthroughs in many ways such as the communication model. The components, both the hardware and software of smartphone and unique computer-featured functions, make smartphones emphasize the user-centered experience, and mobility compared with ordinary telephones and cell phone. Even though the cost of using a smartphone is expensive, with the need to get information quickly, handle official and personal tasks, and facilitate multi-tasking, more and more people are finding they cannot live without smartphones. The smartphone market in China has seen a dramatic increase in recent years. In cities when 3G service is widely available, phones introduced with functional and fashionable features have become absolutely necessary. However, we have to face the fact that in rural areas, ordinary cellphones still play a majority role in the communication market and smartphones have not obtained much market share there. With the fact that the popularity of smartphone is not extended as wide as it is in the cities, one question arises: Is it possible that one day smartphones, with acceptable prices, functional technologies, and practical functions can flourish in rural areas of China? The goal of this research is to test the possibility of the above-mentioned question. To start with, the author develops basic research about smartphones and the current market in China. This is followed by giving an overview of current Economy situation in rural area and the potential influence on Telecom market. Then the author uses the improved Technology Acceptance Model (TAM) to evaluate potential smart phone user’s expectation. To achieve this, a field survey of 299 potential smartphone users from rural areas in China was conducted in order to determine the exact reason they want to purchase a smartphone and what kind of features they require. Based on the result of empirical test, the author finds out that rural residences want to gain users’ experience, status consumption and organization pursuits from smartphone. Besides, although smartphone is an attractive device for rural residences, rural residences have low willingness to purchase. Based on the result, the author hopes that this research can help to answer the question why the current smartphone market in rural area is not established. 빠르게 발전하는 과학기술은 학문간의 장벽을 없애 융합을 촉진하였고, 이러한 융합으로 인해 스마트 시대가 시작되었다. 기술 혁신의 성과인 스마트폰은 사람들의 생활 방식을 완전히 바꾸어 놓았다. 하드웨어와 소프트웨어로 이루어진 스마트폰은 유저 중심의 경험을 제공하고 높은 이동성을 가지고 있다. 스마트폰의 높은 가격에도 불구하고 실시간으로 정보를 교류하고 공적, 사적인 업무의 빠른 처리가 가능하며 다양한 기능을 가지고 있기 때문에 사람들은 스마트폰을 선택한다. 중국의 3G 서비스가 시작된 이래 최근 몇 년간, 중국의 스마트폰 시장은 급성장하였다. 그러나, 중국의 스마트폰 시장에는 불평등이 존재한다. 도시 지역에서는 스마트폰 이용율이 높지만, 농촌 지역에서는 피쳐폰과 유선전화가 시장을 지배하고 있으며 스마트폰의 입지가 매우 작다. 본 연구에서는 스마트폰이 합리적인 가격과 기능으로 농촌시장에 진입할 수 있는 여부에 대하여 연구한다. 우선 스마트폰과 중국 스마트폰 시장에 대해 조사한 후, 중국 농촌의 경제발전 특징에 대한 연구를 진행하여 중국 도시 지역과 농촌 지역 소비자들의 소비 패턴의 차이를 연구한다. 299명의 스마트폰 잠재 소비자에게 설문조사를 시행하고, 설문 데이터를 이용해 개정된 Technology Acceptance Model을 세워, 농촌 지역 소비자가 원하는 스마트폰의 기능과 특징 등에 대해 연구한다. 또한 이를 통해 스마트폰이 중국 농촌 지역에 확산되지 않은 원인을 알아낸다. 본 연구를 통해 스마트폰 업체와 통신사의 전략 수립과 정부의 정책 수립에 도움이 되어 농촌 지역의 스마트폰 확산에 기여할 수 있다.

A Study of Smartphone Addiction among Adolescents in Mongolia

오트곤바야 서울대학교 대학원 2017 국내석사

Although high technology has created many new advancements and services through the population, besides the dark side has appeared in society. The dark side of modern IT technology is having an impact on daily life of youth in several ways including, personal information security problem, overuse, cyber bullying and etc. Adolescents use a smartphone to communicate with their family and friends, to provide their security as well as to obtain a new information and qualitative education however at the same time they are addicted to a smartphone. This study aims to determine factors that influence smartphone addiction the most among the Mongolian adolescents using the regression analysis method. Previous studies show numerous influencing factors based on socioeconomic, psychological and personal characteristics, however this study has the differentiation that is focused on social factors in Mongolian society. The smartphone addiction is possible to be measured by Smartphone Addiction Scale in the research area. The participants, who are aged 13-17, own a smartphone at least two months use. In order to examine and understand the overuse of a smartphone, this study investigates influencing factors that are adolescents’ base on empirical data gathered from a personal interview survey. In Mongolia, the survey was conducted in 21 randomly chosen general educational schools and focused on the students of middle school and high school classes in the year 2016. The thesis was conducted by the empirical study, which included 383 participants, and was analyzed by Ordinary Least-Squares Regression Method. The study was examined by the link between family, school, the use of a smartphone, the awareness of smartphone addiction and compulsive behaviors. The study result suggest that the smartphone addiction is an epidemic problem among Mongolian children especially in the Capital City. By understanding these influencing factors, Mongolian Government Agencies and policy-makers could make a decision and implement planning against to smartphone and internet addiction among adolescents. Lastly, this study gives a rational explanation and suggests policy guidelines on the problem of smartphone addiction for three levels. Keywords: Use of smartphone addiction, Internet addiction, Adolescents, Teenager, Mongolian Society, usage of smartphone, IT policy of addiction

학교 스포츠클럽 참여, 자기 통제력과 스마트폰 중독 간의 구조적 관계

김진성 연세대학교 대학원 2015 국내박사

The purpose of this study was to verify the structural relationship between self-control of middle school students and smartphone addiction and to investigate a moderating effect of sports club in the relation of the self-control and smartphone addiction. The study conducted a research survey through convenient sampling method aimed at middle school students in Seoul. 680 questionnaires distributed and 653 were selected as final valid sample by removing 27 questionnaires that have insufficient answers. Then data were analyzed through frequency analysis, confirmatory factor analysis, reliability analysis, simple regression analysis, correlation analysis, latent mean analysis, structural equation model, and multi-group analysis using SPSS Windows ver. 20.0 and AMOS 18.0. The results were as follows. First, students who spent from 2 to 3 hours per day using smartphone(45.3%) were the majority. When using a smartphone, SNS (33.8%) was found to be the most commonly used and the influence of friends in possession of smartphone(50.7%) was revealed to be the strongest motivation in purchasing smartphone. In addition, the common tendency of smartphone addiction on middle school students revealed that 29.2% of the participants were considered to be in high risk group and 13.9% of then were considered to be in potential risk group. Second, the students who participated in sports club showed significantly higher latent mean value than the students who didn't on delay of gratification and emotional regulation of self-control. Third, the students who participated in sports club showed significantly lower latent mean value than the students who didn't on disturbance of daily living and tolerance of smartphone addiction. Fourth, delay of gratification had a negative effect on smartphone addiction. Fifth, impulse control had a negative influence on smartphone addiction. Sixth, emotional regulation had a negative influence on smartphone addiction. Seventh, the path of impulse control and smartphone addiction had difference between participation in sports club and non-participation in sports club. 본 연구는 중학생의 자기 통제력과 스마트폰 중독과의 관계를 알아보고 학교 스포츠클럽의 조절효과를 규명하고자 하였다. 본 연구의 대상자는 서울 소재 중학교 6곳의 중학생으로 선정하였으며 편의표본추출법을 이용하여 표본을 추출하였다. 총 680부의 설문지 중 응답이 불성실하다고 판단된 27부를 제외한 총 653부를 실제 분석에 이용하였다. 자료처리는 SPSS 20.0 및 AMOS 18.0 프로그램을 이용하여 빈도분석, 확인적 요인분석, 신뢰도 분석, 상관관계분석, 단순 회귀분석, 잠재평균분석, 구조방정식 모형분석 및 다집단 분석을 통해 자료를 분석하였다. 이러한 결과, 다음과 같은 연구결과가 나타났다. 첫째, 중학생의 스마트폰 하루 사용 시간에서는 2시간 이상 3시간 미만이 45.3%로 가장 많았고, 스마트폰 사용 용도는 SNS가 33.8%로 가장 높게 나타났으며, 스마트폰 구입 이유는 친구 때문에가 50.7%로 가장 높게 나타났다. 스마트폰 중독 수준에 따른 사용자 분포는 고위험 사용자군이 전체 연구대상자의 29.2%, 잠재적 위험 사용자군은 13.9%로 나타났다. 둘째, 중학생의 학교 스포츠클럽에 참여하는 학생일수록 자기 통제력의 하위요인 중 만족지연과 정성통제가 평균적으로 더 높은 것으로 나타났다. 셋째, 중학생의 학교 스포츠클럽에 참여하는 학생일수록 스마트폰 중독의 하위 요인 중 일상생활장애와 내성이 평균적으로 낮은 것으로 나타났다. 넷째, 자기 통제력 중 만족지연은 스마트폰 중독에 통계적으로 유의한 영향을 미치는 것으로 나타났다. 다섯째, 자기통제력 중 충동억제는 스마트폰 중독에 통계적으로 유의한 영향을 미치는 것으로 나타났다. 여섯째, 자기 통제력 중 정서통제는 스마트폰 중독에 통계적으로 유의한 영향을 미치는 것으로 나타났다. 일곱째, 학교 스포츠클럽 참여집단과 비참여집단은 충동억제와 스마트폰 중독의 경로에서만 그 차이가 있는 것으로 나타났다.