Microfluidic capacitive sensors with ionic liquid electrodes and CNT/PDMS nanocomposites for simultaneous sensing of pressure and temperature

Yoon, Sun Geun,Chang, Suk Tai The Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.8

<P>We report a new class of simple fluidic capacitive sensors based on microfluidic techniques, which are capable of multimodal sensing performances. The microfluidic multifunctional capacitive sensors were realized by using ionic liquids acting as electrodes in microchannels and a CNT/PDMS composite as a dielectric layer. Our microfluidic capacitive sensors offer outstanding sensor performance to detect localized pressure and even lateral pressure variation as well as ambient temperature changes. The principle of our new microfluidic capacitive sensors is explained by the electric double layer capacitance and the ion distribution along the ionic liquid electrodes. In order to demonstrate their capability for practical usage, our simple structured microfluidic capacitive sensors were applied to a bottle and human skin for monitoring the variation of pressure and temperature simultaneously. The highly sensitive microfluidic capacitive sensors were successfully applied as keypads and potential platforms for distinctively detecting various hand or finger motions such as tapping, scratching, and stacking. Our novel microfluidic multimodal capacitive sensors show great promise for making future stretchable electronic devices, such as wearable electronics, soft robotics, and artificial skin.</P>

하천형 저수지 팔당호의 육수학적 특성: 수문과 수환경 요인

신재기 ( Sin Jae Gi ),황순진 ( Hwang Sun Jin ),강창근 ( Kang Chang Geun ),김호섭 ( Kim Ho Seob ) 한국하천호수학회 2003 생태와 환경 Vol.36 No.3

This study aimed to determine the relationship between rainfall-discharge patterns and major aquatic environmental factors in a river-type reservoir. Specifically, daily monitoring was conducted in Paltang Reservoir from January 1999 to December 2001. Observation of the daily changes of the environment factors showed that natural meteorological factors and hydrological factors causing the change of water discharge had a major effect on the aquatic environment. Rainfall was the main source of hydrological changes, with its frequency a possible direct variable governing the range of discharge changes. Rainfall was weak in November~ May and heavy in June~October (heavist in summer). The range of water discharge was greatest during summer(July to September) and lowest during winter(january to February). A principal component analysis (PCA) showed that aquatic environmental factors could be classified into three different types in the pattern of annual variation. First, type I included water temperature, turbidity, water color and organic matter(COD), which increased with increasing water discharge. Second, type Ⅱ consisted of DO and pH, which decreased with increasing water discharge. Third type Ⅲ included conductivity, alkalinity and chloride ion, which showed middle values with increasing water discharge, Monthly variation of aquatic environments explained by the first two dimensions of PCA suggests that aquatic environments explained by the first two dimensions of the PCA suggests that aquatic environments of Paltang Reservoir may have annual cycle typical of river-type reservoirs depending on hydrological factor such as water discharge.

한국인 직무 스트레스 측정도구의 개발 및 표준화

장세진,고상백,강동묵,김성아,강명근,이철갑,정진주,조정진,손미아,채창호,김정원,김정일,김형수,노상철,박재범,우종민,김수영,김정연,하미나,박정선,이경용,김형렬,공정옥,김인아,김정수,박준호,현숙정,손동국 大韓産業醫學會 2005 대한직업환경의학회지 Vol.17 No.4

Background and Purposes: Over the past three decades, numerous studies performed in Korea have reported that job stress is a determinant risk factor for chronic diseases and work disability. Every society has its own culture and occupational climate particular to their organizations, and hence experiences different occupational stress. An occupational stress measurement tool therefore needs to be developed to estimate it objectively. The purpose of this study is to develop and standardize the Korean Occupational Stress Scale (KOSS) which is considered to be unique and specific occupational stressors in Korean employees. Subjects and Methods: Data were obtained from the National Study for Development and Standardization of Occupational Stress (NSDSOS Project: 2002-2004). A total of 12,631 employees from a nationwide sample proportional to the Korean Standard Industrial Classification and the Korean Standard Occupational Classification were administered. The KOSS was developed for 2 years (2002-2004). In the first year, we collected 255 items from the most popular job stress measurement tools such as JCQ, ERI, NIOSH and OSI, and 44 items derived from the a qualitative study (depth interview). Forty-three items of KOSS, in the second year, were retained for use in the final version of the KOSS by using Delphi and factor analysis. Items were scored using conventional 1-2-3-4 Likert scores for the response categories. Results: We developed eight subscales by using factor analysis and validation process: physical environment (3 items), job demand (8 items), insufficient job control (5 items), interpersonal conflict (4 items), job insecurity (6 items), organizational system (7 items), lack of reward (6 items), and occupational climate (4 items). Together they explained 50.0% of total variance. Internal consistency alpha scores were ranged from 0.51 to 0.82. Twenty-four items of the short form of the KOSS (KOSS-SF) were also developed to estimate job stress in the work setting. Because the levels of the subscales of occupational stress were gender dependent, gender-specific standard norms for both the 43-item full version and the 24-item short form using a quartile for the subscales of KOSS were presented. Conclusion: The results of this study suggest that KOSS might be an appropriate measurement scale to estimate occupational stress of Korean employees. Further and more detailed study needs to be conducted to improve the validity of this scale.

치환 Phenacyl Bromide와 Benzimidazole간의 반응에 관한 반응속도론적 연구

盧載根,金昌錫,洪淳瑛,金沂宣 漢陽大學校 自然科學硏究所 1997 自然科學論文集 Vol.16 No.-

몇 가지 meta 또는 para 치환 phenacyl bromide 와 benzimidazole간의 친핵성 치환 반응의 속도를 전기 전도도법을 이용하여 측정하였으며 이 반응 속도로부터 활성화 파라미터를 계산하였다. 이들 반응은 phenacyl bromide의 전자 끄는 기에 의해 촉진되었고 치환기의 전자적 성질과 반응 속도 사이에는 Hammett rule이 잘 적용되었다. 활성화 엔탈피와 엔트로피의 관계는 등속 관계를 따랐으며 이때 등속 온도는 278 K로 나타났다. 반응 속도는 용매의 극성이 커짐에 따라 빨라졌으며 용매의 유전 상수와 반응 속도 상수 사이에는 Kirkwood rule이 잘 적용되었다. 반응 속도론적 연구 결과로부터 이들반응은 전형적인 S?2 과정으로 진행하며 활성화 착물에서 phenacyl bromide의 C-Br 결합 해리 보다 benzimidazole의 질소와 phenacyl bromide의 methylene 탄소 사이의 C-N 결합 형성 과정이 반응 속도 결정 단계임을 알 수 있었다. Reaction rates of several m- or p-substituted phenacyl bromides with benzimidazole were measured by an electric conductivity method and activation parameters relevant to these reactions were calculated. Reactions were enhanced by electron-withdrawing substituents, and the relation between reaction rate and electronic nature of the substituent obeyed the Hammett rule. From plots of activation enthalpy against activation entropy, an isokinetic temperature was found to be 278 K. Reaction rates were increased in a more polar solvent and obeyed the Kirkwood rule well. From the observed kinetics, it was concluded that these reactions proceed through a typical ??? path, and the formation of C-N bond between methylene carbon of phenacyl bromide and benzimidazole nitrogen, rather than the cleavage of C-Br bond in phenacyl bromide, is a rate determining step in the activated complex.

조기(早期) 한방치료(韓方治療)를 시행한 요추수핵탈출증(腰椎髓核脫出症) 환자(患者)의 C-T 상(上) 5-7년 후의 추간판(椎間板)의 변화(變化)

문형철,황우준,이건목,조남근,강성도,조재운,장병선,진경선,Mun, Hyung-Cheal,Hwang, Woo-Jun,Lee, Geon-Mok,Cho, Nam-Geun,Gang, Sung-Do,Cho, Jae-Woon,Chang, Byoung-Sun,Jin, Kyong-Son 대한침구의학회 2001 대한침구의학회지 Vol.18 No.4

Study design : A retrospective study of lumbar disc herniations using results of follow-up computed tomographic scan examinations. Objective : Lumbar disc herniations is one of the cause low back pain and lower extremity pain. To clarify the lumbar disc herniations morphological changes over time(mean 5.3 years) in order to establish a strategy for treatment. Methods : Sixteen patients with lumbar disc herniations who underwent follow-up computed tomographic scan examinations were studied. The changes over time in herniated disc size(herniation ratio) were evaluated using this scan technique. The initial computed tomographic scan allowed classification of the herniations according to herniation ratio: small, medium and large. Results : Comparison with follow-up computed tomographic scans showed that of the 16 patients, in 14 patients(88%), the herniation ratio(HR) was decreased and among them, 8 patients had complet resolution of herniated disc. In 2 patients with small herniations, the HR of one case was increased, the other was decreased. In 8 patients with medium herniations, the HR of one case had no change, the others was decreased. In 6 patients with large herniation, the HR of all patients was decreased. Interestingly, 4 of the 16 patients showed calcification change of herniated disc. Conclusion : There is no doubt that herniated disc size is decreased over time. The largest herniations were those which had the greatest tendency to decrease in size. But in some cases, the HR was increased, or calcification change was showed.

내용 : 구조화 정도가 다른 수학적 동형 문제 사이의 유추적 전이 분석

성창근 ( Chang Geun Sung ),박성선 ( Sung Sun Park ) 한국수학교육학회 2012 初等 數學敎育 Vol.15 No.2

This study aims to find whether the solutions for well-structured problems learned in school can be transferred to the moderately-structured problem and ill-structured problem. For these purpose, research questions were set up as follows: First, what are the patterns of changes in strategies used in solving the mathematics problems with different level of structuredness? Second, from the group using and not using proportion algorithm strategy in solving moderately-structured problem and ill-structured problem, what features were observed when they were solving That Problems? Followings are the findings from this study. First, for the lower level of structuredness, the frequency of using multiplicative strategy was increased and frequency of proportion algorithm strategy use was decreased. Second, the students who used multiplicative strategies and proportion algorithm strategies to solve structured and ill-structured problems exhibited qualitative differences in the degree of understanding concept of ratio and proportion. This study has an important meaning in that it provided new direction for transfer and analogical problem solving study in mathematics education.

Application of Landscape Ecology to Ecological Restoration

Hong, Sun-Kee,Kang, Ho-jeong,Kim, Eun-Shik,Kim, Jae-Geun,Kim, Chang-Hoe,Lee, Eun-Ju,Lee, Jae-Chun,Lee, Jeom-Sook,Choung, Yeon-sook,Choung, Heung-Lak,Ihm, Byun-Sun The Ecological Society of Korea 2004 Journal of Ecology and Environment Vol.27 No.5

To date, restoration ecology has focused on local areas, particularly small-scale ecosystems. As such, restoration ecology has been applied to areas with clear boundaries, such as roads, abandoned mines, wetlands, and forest ecosystems. However, those involved in these restoration efforts, due to their tendency to implement comprehensive plans to change the landscape structure, and their mismanagement of the restoration process, have more often than not wound up weakening the ecological functions of surrounding ecosystems, and in further degrading the ecosystem which they were trying to restore. To resolve these problems and restore a comparatively large-scale region, methods to assess the impact of such restoration efforts on surrounding ecosystems must be developed. These include expanding the scale of restoration efforts; in other words, moving from the local to the landscape scale. As a conclusion, practice of ecological restoration is increasingly moving towards landscape scale in order to deal with these problems.

Highly Sensitive Piezocapacitive Sensor for Detecting Static and Dynamic Pressure Using Ion-Gel Thin Films and Conductive Elastomeric Composites

Yoon, Sun Geun,Park, Byoung Joon,Chang, Suk Tai American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.41

<P>A new class of simple and highly sensitive piezocapacitive sensors that are capable of detecting static and dynamic pressure changes is reported. The pressure sensor structure is formed by vertically sandwiching a sandpaper-molded carbon nanotube/poly-(dimethylsiloxane) composite (CPC) dielectric layer between two ion gel thin film electrodes. Such a capacitive sensor system enables the distinguishable detection of directional movement of applied pressure as well as static pressure variation by modulating ion distribution in the ion-gel thin films. The resulting capacitive pressure sensors exhibit high sensitivity (9.55 kPa(-1)), high durability, and low operating voltage (0.1 V). Our proposed pressure sensors are successfully applied as potential platforms for monitoring human physiological signals and finger sliding motions in order to demonstrate their capability for practical usage. The outstanding sensor performance of the pressure sensors can permit applications in wearable electronic devices for human-machine connecting platforms, health care monitoring systems, and artificial skin.</P>

종격동 종양에 의한 횡격막상부 식도 게실 1예

장경순(Gyeong Sun Chang),김도민(Do Min Kim),권재성(Jae Sung Keun),이성근(Sung Keun Lee),박세종(Se Jong Park),윤순일(Sun Il Yoon),강종렬(Jong Yael Kang),김응수(Eung Soo Kim),이근찬(Geun Chan Lee) 대한내과학회 2000 대한내과학회지 Vol.59 No.2

Epiphrenic diverticulum(traction type) is such a rare disease. The case of this disease which is due to mediastinal tumor, not because of inflammatory adhesion or of motor disorder is especially hard to find. The patient was a 50-year-old male and admitted with the intermittent postprandial chest discomfort. The chest CT and esophagography showed epiphrenic diverticulum(traction type). The tumor was located at the left anterolateral of thoracic spine, adhered to the right wall of esophagus. We performed the diverticulectomy and extirpation of mediastinal tumor under left posterolateral thoracotomy. The tumor and the esophagus were well seperated without invasion to the esophagus. In the pathology of resected tissues, solitary neurofibroma was diagnosed. There was no complication or recurrence after surgical resection.(Korean J Med 59:225-229, 2000)

폐경 후 여성에서 에스트로겐 수용체 유전자의 thymine-adenine 반복 다형성과 호르몬 대치요법에 대한 지질대사와 골밀도 변화의 관계

임창훈 ( Im Chang Hun ),황창선 ( Hwang Chang Seon ),강영순 ( Kang Yeong Sun ),문인걸 ( Mun In Geol ),김성훈 ( Kim Seong Hun ),정호연 ( Jeong Ho Yeon ),한기옥 ( Han Gi Og ),장학철 ( Jang Hag Cheol ),박원근 ( Park Won Geun ),윤현구 대한내과학회 2003 대한내과학회지 Vol.65 No.2

Background : Several biologically plausible mechanisms have been proposed for estrogen- associated changes in lipid and bone metabolism. These effects are thought to be mediated via estrogen receptor (ER). Several polymorphisms in the gene encoding estrog