Improving mechanical properties of bioinspired Clay-Cellulose Nanofibers composites

허재은,장다슬,배은실,심봉섭 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

In nature, nacre has the hierarchical brick-and-mortar structures and precise inorganic-organic interfaces, which enable it to achieve remarkably high fracture toughness and tensile strength. Because of these properties, nacre-mimetics hold great potential as mechanical high-performance and functional materials. Previously, we have fabricated nacre-like nanocomposites via vacuum filtration of montmorillonite (MMT) and cellulose nanofibers(CNFs) mixtures. Although the composites exhibited higher strength and toughness than pure MMT and CNFs, we tried to improve the mechanical properties further y by additional post treatmentsive work. In this study, adding polymers and cross-linking were introduced to improve the mechanical propertiesy of the composites. The resulting materials were analyzed by a Scanning electron microscopy(SEM), an X-ray diffraction(XRD), and a tensile tester. We compare the resulting mechanical properties with the previous results.

흑연을 이용한 전도성 잉크

허재은,심봉섭 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

전도성 잉크는 카본 블랙, 흑연, 금속 입자 등의 전도성 나노물질을 유기용매 등에 섞어서 전기적 전도성을 가지도록 제작된 잉크를 말하며, 이는 잉크젯 및 프린팅 방법으로 다양한 전기회로, 전극, RFID, 안테나 및 센서 등을 제작하는데 사용되는핵심 소재이다. 전도성 잉크의 필수 조건으로는 높은 전기적 전도성, 낮은 가격, 분산 용이성 등을 중요한 요소로 꼽을 수 있는데 특히 탄소 기반 물질들은 높은 전도성을 가지며 값싼 생산을 가능하게 한다는 특징을 가지고 있다. 본 실험에서는 압저항 센서에 사용되는 전도성 잉크를 만들기 위하여 흑연을 이용하였다. 먼저Hummers법으로 흑연을 가볍게 산화시킨 후 Poly sodium 4-styrene sulfonate(PSS)로 안정화하고 물, organic solvent 등에 분산시켜 전도성 잉크의 프린팅 회로의 전도성을 비교하였다. 또한 SEM 분석을 통해 표면구조를 관찰하였고 zetapotential을 측정하여 산화된 흑연의 분산정도를 비교하였다.

Effects of process variables on aqueous-based AlOx insulators for high-performance solution-processed oxide thin-film transistors

허재은,박진택,이준희,이성은,이진원,임건희,김연상 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.68 No.-

Recently, aqueous method has attracted lots of attention because it enables the solution-processed metal oxide thin film with high electrical properties in low temperature fabrication condition to various flexible devices. Focusing the development of aqueous route, many researchers are only focused on metal oxide materials. However, for expansive application of the aqueous-based metal oxide films, the systematic study of performance change with process variables for the development of aqueous-based metal oxide insulator film is urgently required. Here, we propose importance of process variables to achieve high electrical-performance metal oxide insulator based on the aqueous method. We found that the significant process variables including precursor solution temperature and humidity during the spin-coating process strongly affect chemical, physical, and electrical properties of AlOx insulators. Through the optimization of significant variables in process, an AlOx insulator with a leakage current value approximately 105 times smaller and a breakdown voltage value approximately 2–3 times greater than un-optimized AlOx was realized. Finally, by introducing the optimized AlOx insulators to solution-processed InOx TFTs, we successfully achieved InOx/AlOx TFTs with remarkably high average field-effect mobility of ∼52 cm2 V−1 s−1 and on/off current ratio of 106 at fabrication temperature of 250 °C.

의식적인 보조학습이 중학교 수학교육에서 학습태도와 학업성취도에 미치는 영향

허재은,김홍찬 한국수학교육학회 2011 수학교육 학술지 Vol.2011 No.2

본 연구는 학생의 의식적인 보조학습 선택이 학교 수학교육에서 학습태도와 학업성취도에 미치는 영향을 규명하여 중학교 수학 학습에 있어 학생들이 합리적인 공부 방법을 선택하도록 돕는 데 그 목적이 있다. 이를 위해 자기조절 학습능력과 학생 보조학습 선택 과정의 관계, 의식적 보조학습 선택과 수학 학습에서의 메타인지 능력의 상관관계, 그리고 의식적인 보조 학습 선택이 수학학습 태도와 학업성취도에 주는 영향을 연구하였다.

자기조절학습능력이 중학교 수학교육에서 보조학습 선택 과정과 결과에 미치는 영향 분석

허재은,김홍찬 한국학교수학회 2014 韓國學校數學會論文集 Vol.17 No.1

본 연구는 자기조절학습능력의 관점에서 중학생들의 수학 보조학습 선택, 유지, 변경 과정 과 그 효과를 분석하여 학생들이 합리적인 공부 방법을 선택하도록 돕는 데 그 목적이 있다. 이를 위해 학생들의 보조학습 선택, 유지, 변경 과정과 수업참여 적극성, 보조학습 성과로서 인지적, 정의적 영역의 변화를 정성적으로 분석하였다. 연구 결과, 자기조절학습능력이 높은 학생들은 자기조절학습능력이 낮은 학생들에 비해 첫째, 본인의 학습 과정과 보조학습이 자 신에게 미치는 영향에 대해 구체적으로 판단하고 합리적 근거로 보조학습을 선택, 유지, 변 경하였다. 둘째, 수업참여 적극성이 높고 내재적 동기에 의한 적극적 행동이 많았다. 셋째, 보조학습이 자신의 수학학습에 미친 영향을 구체적으로 느끼고 본인의 공부 방법에 확신이 있어 수학적 흥미와 자신감이 향상되었다고 느꼈다. This research aims to analyze the process of selecting, maintaining, and changing the method of learning mathematics by middle school students from the perspective of self-regulated learning ability, in order to help students to select a rational method of studying. For this purpose, we defined ‘assisted-learning’ as all kinds of education that education demanders receive to supplement their regular school studies. As results of the research, it was found as follows. First, the students with high self-regulated learning ability selected, maintained, and changed their assisted-learning based on their concrete decision and rational reasons regarding the effect of their learning process and assisted-learning to themselves. Second, the students with high self-regulated learning ability had tendency to be very active participation in class than the students with low ability. Third, the students with high self-regulated learning ability felt the effect of assisted-learning on their learning mathematics, and felt the enhancement of their interest and confidence. Also, it is notable that the students selected ‘their own willingness to study’ as a major factor for the success of assisted-learning.

Critical Factors Influencing on Aqueous-Route Fabrication of High-Quality Aluminum Oxide Insulator Film

허재은,임건희,박진택,이준희,이성은,김연상 한국진공학회 2018 한국진공학회 학술발표회초록집 Vol.2018 No.2

체간의 견인-진동이 요통 및 삶의 질에 미치는 영향

허재은,오세준,장건희,김성국,윤범철 대한스포츠물리치료학회 2023 정형스포츠물리치료학회지 Vol.19 No.2

Purpose: The aging population is contributing to the increasing prevalence of chronic and degenerativediseases. According to the 2020 National Survey of the Elderly, the prevalence of chronic diseases amongthe elderly is 84.0%, with musculoskeletal disorders – arthritis, low back pain, and sciatica – ranking amongthe top five chronic diseases. The primary complaint of individuals with chronic musculoskeletal conditionsis pain, and the spine is the most common site of pain. Chronic low back pain is a major cause of functionallimitations related to the performance of activities of daily living in older adults, affecting not only physicalfunction but also psychological aspects. These problems ultimately lead to a decreased quality of life andincreased societal costs. Therefore, there is a need for effective and accessible methods to manage chroniclow back pain at home on a regular basis. In this study, we aimed to comprehensively evaluate the effectsof applying a traction and vibration device to the body of elderly people with chronic low back pain todetermine the multifaceted effects of the device. Methods: Twenty-one subjects aged 65 years or older with chronic low back pain applied an interbodytraction-vibration device for approximately 10 minutes twice a week for four weeks. Outcome measures includedpain intensity (VAS), muscle biomechanical properties (Myoton PRO), quality of life (EQ-5D), level of functionaldisability (ODI), stress (uBioMacpa), and device safety and satisfaction (semi-structured questionnaire). Results: Significant improvements in pain intensity (p<0.01), muscle stiffness (p<0.05), functional disabilitylevel (p<0.05), and stress (p<0.05) were observed at pre- and post-test after the intervention, but no significantchanges were observed in quality of life and muscle tone and elasticity. More than 80% of the subjects weresatisfied with the interbody traction and vibration device, and no other adverse events were reported. Conclusion: This study confirmed the multifaceted effects of interbody traction and vibration on pain intensity,muscle biomechanical properties, quality of life, level of functional disability, and stress in older adults withchronic low back pain, as well as the safety and high level of satisfaction with the device.

Piezoresistive Film Composed of Carbon-Black and Polyurethane

허재은,심봉섭 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.1

Highly crystalline cellulose from natural tunicates and analysis of thermal and mechanical properties

허재은,심봉섭 한국고분자학회 2017 한국고분자학회 학술대회 연구논문 초록집 Vol.42 No.2

논문 : 이용과 충족 관점에서의 디지털 사이니지 사용자 상호작용성 연구

허재은 ( Jae Eun Heo ),박승호 ( Seung Ho Park ) 디자인융복합학회 2014 디자인융복합연구 Vol.13 No.1

디지털 사이니지는 기술의 발전과 함께 다양한 콘텐츠를 제공하고 사용자에게 새로운 경험이라는 가치를 제공하는 혁신적인 커뮤니케이션 매체로 급부상하고 있다. 본 연구는 디지털 사이니지의 사용자의 이용동기와 태도, 상호작용성, 향후 이용 의도의 관계를 알아보고자 이용과 충족이론, 상호작용성, 디지털사이니지의 선행 연구를 통해 이론적 틀을 정리하고, 이를 실증적 분석을 통하여 연구하였다. 디지털 사이니지의 이용동기는 '정보성' 이 가장 영향을 미치는 것으로 나타났으며, 이용동기가 태도와 상호작용성에 미치는 영향은 정보성, 엔터테인먼트, 시간활용의 디지털 사이니지 이용동기가 높을수록 지각된 상호작용성이 높은 것으로 나타났고, 태도에 미치는 영향이 유의미하였다. 또한 지각된 상호작용성이 높을수록 태도는 긍정적이며, 태도가 긍정적일수록 향후 지속 이용의도가 높았다. 본 연구는 디지털 사이니지 환경 하에서 이용과 충족 이론 및 상호작용성의 이론적 틀의 가치를 실증적으로 규명한 사용자 중심의 연구로 의미가 있다. 향후 디지털 사이니지의 콘텐츠 제공에 있어 도움이 되리라 예상되며, 구체적인 상호작용 요소나 세부효과 측정으로 보다 발전된 연구가 가능할 것이다. Digital Signage is making a meteoric rise as an innovative communications media that provides various contents and values of new experience to its users. This study was conducted by organizing and empirically analyzing a theoretical outline through the theory of uses and gratification, interactivities, and preceding research on digital signage, in order to look into the relationships of usage motivation and attitude, interactivities, and future usage intentions of users. As for usage motivations of digital signage, 'information' was shown to be most influential, and in the case of the effects of usage motivations on attitude and interactivities, the higher the information, entertainment, and pass time of digital signage usage motivations, the perceived interactivities were higher, the rest usage motivations showed significant effects on attitude. Also, the higher the perceived interactivities, attitudes showed to be more positive and more positive attitudes showed higher future continuous usage intentions. This study has its meaning as a study focusing on users by empirically establishing the value of the theoretical outline of the theory of uses and gratification and interactivities under digital signage environment. This is determined to be helpful in terms of digital signage providing contents or advertisement, and also a more developed study is expected to be possible with specific interaction factors or measuring detailed effects of future digital signage.