Experimental assessment of on-chip liquid cooling through microchannels with de-ionized water and diluted ethylene glycol

Won, Yonghyun,Kim, Sungdong,Kim, Sarah Eunkyung IOP Publishing 2016 Japanese journal of applied physics Vol.55 No.6

<P>Recent progress in Si IC devices, which results in an increase in power density and decrease in device size, poses various thermal challenges owing to high heat dissipation. Therefore, conventional cooling techniques become ineffective and produce a thermal bottleneck. In this study, an on-chip liquid cooling module with microchannels and through Si via (TSV) was fabricated, and cooling characteristics were evaluated by IR measurements. Both the microchannels and TSVs were fabricated in a Si wafer by deep reactive ion etching (DRIE) and the wafer was bonded with a glass wafer by a anodic bonding. The fabricated liquid cooling sample was evaluated using two different coolants (de-ionized water and 70 wt% diluted ethylene glycol), and the effect of coolants on cooling characteristics was investigated. (C) 2016 The Japan Society of Applied Physics</P>

중등예비교사들의 교원 핵심역량에 대한 인식 분석

문은경 ( Eunkyung Moon ),신원석 ( Won Suk Shin ),박인우 ( Innwoo Park ) 안암교육학회 2016 한국교육학연구 Vol.22 No.1

본 연구는 예비교사에게 요구되는 교원 핵심역량을 규명하고, 현재 예비교사들의 역량 수준 및 사범대학의 교육과정 만족도에 대한 인식을 조사하여 예비교사들의 핵심역량 신장을 위한 교육과정 개선방안을 분석하는데 그 목적이 있다. 이를 위해 교원의 전문성 및 교사역량과 관련된 국내외 문헌들을 고찰하여 교원역량을 구성하였고, 이를 바탕으로 교육학 및 교과교육학 전문가 20인으로 구성된 전문가 집단의 협의회 및 설문조사 결과를 통해 최종 교원 핵심역량을 확정하였다. 다음으로 교육과정 개선방안을 위한 우선순위를 분석하기 위해서 사범대학 재학생 312명을 대상으로 핵심역량 현재수준 및 사범대학 교육과정 만족도에 대한 인식을 조사하여 항목별로 대응표본 t-검정으로 그 차이를 분석하였고, 현재수준과 만족도의 평균을 기준으로 하는 2차원 분석틀을 활용하여 교육과정 개선을 위한 우선순위를 분석하였다. 연구결과, 교원 핵심역량은 교과 전문지식, 전문 소양, 학생과의 관계 형성, 의사소통, 학급 운영 및 관리, 수업계획 및 개발, 수업진행, 평가 및 피드백, 다문화, 세계화, 정보화의 총 11개 영역으로 구성되었다. 그리고 예비교사들의 현재 역량수준과 교육과정 만족도에 대한 인식 차이를 분석결과, 수업진행 영역의 ICT 활용능력 역량을 제외한 모든 역량들에서 그 차이가 유의미한 것으로 나타났다. 또한, 핵심역량 현재수준 및 사범대학 교육과정 만족도의 2차원 분석틀을 통해 교육과정 개선을 위한 우선순위를 분석하였다. 마지막으로 본 연구결과에 근거하여 예비교사들의 핵심역량을 효과적으로 개발하기 위한 사범대학의 교육과정 개선에 대한 시사점을 논의하였다. The purpose of this study was to investigate teachers` core competence, and analyse pre-service teachers` perception of their competence and satisfaction of curriculum. Then, the way of reform of curriculum for enhancing pre-service teachers` core competence was proposed. The studies on teachers` expertise and competence were reviewed to draw the core competence of a teacher. The designed teacher`s competence model was used to assess the current status of core competence and the status of support by the college of education. The 312 pre-service teachers responded the survey instrument. An analysis of differences between the current status and satisfaction was performed, and the order of priority was analyzed using two-dimensional analyzing tool. The results of this study are following. 1) The teachers` core competence consists of 11 areas such as content knowledge, teaching attitude, teacher-student relation, communication, class management, design and develop lesson, instructional strategies, evaluation and feedback, multi-cultural attitude, globalization, and information and communication technology. An analysis of the differences between the current status and satisfaction showed that pre-service teachers perceived low level of supports by college of education generally. Finally, the implications on revising and reformation of curriculum for acquiring teaching certificate were discussed.

Mature Defense Mechanisms Affect Successful Adjustment in Young Adulthood-Adjustment to Military Service in South Korea

Ji-Won Nam,Jee Hyun Ha,Eunkyung Choi,Doo-Heum Park,Seung-Ho Ryu 대한신경정신의학회 2019 PSYCHIATRY INVESTIGATION Vol.16 No.7

Objective A defense mechanism is an automatic psychological process necessary for successful adaptation. It reflects adaptive capacity. The purpose of this study is to explore the relationship between the adaptation ability of individuals who face mandatory military service and the pattern of defense mechanisms. Methods The subjects were 69 men (21.4±2.2 years) who expressed psychological difficulties in three military service situations. Control group was 36 men (24.0±1.4 years) who had successfully completed military service. We examined psychiatric history, the pattern of defense mechanisms, and depression and anxiety levels. Defense mechanisms were compared between two groups. Results The maladjusted group used immature defenses more frequently than the control group did. There were no differences in the defense patterns according to diagnosis. The control group used more identification and rationalization, classified as immature defenses. The temporarily maladjusted group used more somatization, regression, and avoidance. Conclusion Using mature defense mechanisms helped young adults to adapt to a particular situation. The maturity of the defense is more valuable than the psychiatric diagnosis. Some immature defenses are also helpful to adapt. We cautiously assume that some defenses can be protective or risk factors in adapting to stressful situations by young adults.

학교현장실습이 예비교사들의 좋은 수업 행동에 대한 인식에 미치는 영향

신원석(Won Sug Shin),이용진(Yongjin Lee),문은경(Eunkyung Moon) 한국교육방법학회 2018 교육방법연구 Vol.30 No.2

본 연구는 교원양성 교육과정과 학교현장실습의 구체적인 지원 및 개선을 위한 시사점을 도출하고자, 예비교사들의 ‘좋은 수업 행동’에 대한 인식을 학교현장실습 전후에 걸쳐 살펴보고자 하였다. 이에 좋은 수업 행동의 중요수준과 실행수준에 대한 인식차이가 학교현장실습 전후에 어떻게 달라지는 지와 수업시연 정도에 따라 차이가 있는지 확인해 보고자 하였다. 설문은 서울소재 K대학의 예비교사들을 대상으로 이루어졌으며, 학교현장실습 전후 좋은 수업을 위한 행동들에 대한 중요수준 및 실행수준에 대한 인식을 분석 한 결과, 예비교사들이 인식하고 있는 ‘좋은 수업 행동’에 대한 전반적인 중요도가 실행도에 비해 높게 나타났다. 구체적으로 중요도에 비하여 학교현장실습 후에 인식하는 실행도가 유의하게 달라진 것은 20문항 중 8개 문항(학생의 환경 이해, 개별 수준에 따른 기회 제공, 개별 학생 이해, 오개념 파악 및 활용, 수업 목표 도달 파악, 수업 내용 명확히 전달, 수업진도에 충실, 테크놀로지 활용)으로 나타났다. 중요도-실행도 분석결과, ‘집중’면에 3개 항목(학생의 환경 이해, 개별 수준에 따른 기회 제공, 오개념 파악 및 활용), ‘유지’면에 10개 항목, ‘후순위’면에 7개 항목이 속하는 것으로 나타났다. 그리고 수업 시연 정도에 따른 인식변화에 유의한 차이가 있는 문항은 3개 항목(테크놀로지 활용, 수업진도에 충실, 오개념 파악 및 활용)으로 나타났다. 본 연구의 결과는 예비교사들을 대상으로 ‘좋은 수업’을 위한 행동에 대한 중요도와 실행도가 학교현장실습을 기준으로 어떻게 달라지는지를 알아봄으로써 예비교사교육에 대한 함의점을 찾아보고자 했다는 점에서 의의가 있다. The purpose of this study was to examine the perception of pre-service teachers’ ‘good teaching’ and change of their perception on the basis of teaching practicum. This study tried to confirm whether the perception difference before and after the practicum varies according to the experience of teaching demonstration. Therefore, this study was to provide and suggest implications for the improvement and support of the teaching practicum. The questionnaires were distributed to the pre-service teachers of K university in Seoul through online, and it was about the level of importance and performance of good teaching behaviors before and after teaching practicum. The results showed that the overall importance of pre-service teachers was higher than that of practice. Specifically, eight items were found to have significantly different perceptions of perceived performance after school practice compared to their importance. As a result of the importance-performance analysis, it was found that three items were included in the ‘Concentration’ side, ten items in the ‘Keep up the good work’ side, and seven items in the ‘Low priority’ side. There were 3 items with significant difference in perception change according to the class demonstration level. This study have the implications of the pre-service teacher education by examining how the importance and performance of ‘good teaching’.

Promoter hypermethylation of the p16 gene is associated with poor prognosis in recurrent early-stage hepatocellular carcinoma.

Ko, Eunkyung,Kim, Yujin,Kim, Sung-Joo,Joh, Jae-Won,Song, SangYong,Park, Cheol-Keun,Park, Joobae,Kim, Duk-Hwan American Association for Cancer Research 2008 Cancer epidemiology, biomarkers & prevention Vol.17 No.9

<P>Despite significant advances in the detection and treatment of hepatocellular carcinoma, the prognosis of patients with hepatocellular carcinoma remains very poor, in part due to the high incidence of recurrence. This study was aimed at identifying a prognostic indicator of recurrence in patients with hepatocellular carcinoma. We retrospectively analyzed CpG island hypermethylation of the p14, p15, p16, GSTP1, integrin alpha4, SYK, and CDH1 genes in fresh-frozen tissues from 265 patients with hepatocellular carcinoma using the methylation-specific PCR. The expression levels of p16 and p53 were evaluated by immunohistochemistry. CpG island hypermethylation was detected in 6% for p14, 21% for p15, 67% for p16, 75% for GSTP1, 23% for integrin alpha4, 12% for SYK, and 57% for CDH1. Recurrence was observed in 102 (38%) of the 265 patients. There was no association between the risk for recurrence and hypermethylation of any gene studied. However, p16 methylation was associated with a poor survival after surgery for recurrent stage I to II hepatocellular carcinomas (hazard ratio, 4.05; 95% confidence interval, 1.15-14.20; P = 0.03). In addition, the hazard of failure after recurrence was about 3.80 (95% confidence interval, 1.03-14.20; P = 0.04) times higher in patients with p16 methylation than in those without. Negative expression of p16 at a protein level was also associated with poor survival in recurrent stage I to II hepatocellular carcinomas, but p53 expression did not have a synergistic effect on the poor prognosis. In conclusion, the present study suggests that p16 methylation may be associated with a poor prognosis in recurrent early-stage hepatocellular carcinomas.</P>

A Study on Proton Conductivity of Composite Membranes with Various Ionic Liquids for High-Temperature Anhydrous Fuel Cells

Cho, EunKyung,Park, Jin-Soo,Sekhon, S. S.,Park, Gu-Gon,Yang, Tae-Hyun,Lee, Won-Yong,Kim, Chang-Soo,Park, Seung-Bin The Electrochemical Society 2009 Journal of the Electrochemical Society Vol.156 No.2

Analysis of low molecular weight plasma proteins using ultrafiltration and large gel two-dimensional electrophoresis

Jung, Woon-Won,Phark, Sohee,Oh, Sangnam,Khim, Jin-Young,Lee, Juneyoung,Nam, Myung Hee,Seo, Jong Bok,Park, So-Young,Jo, Eunkyung,Choi, Seonyoung,Zheng, Zhi,Lee, Ji Young,Lee, Min,Lee, Eunil,Sul, Dongge WILEY-VCH Verlag 2009 Proteomics Vol.9 No.7

<P>In this study, various solvent systems were applied to obtain a high and consistent recovery rate of low molecular weight plasma proteins (LMPP) from human plasma. A buffer system containing 7 M urea, 2 M thiourea, 25 mM NH<SUB>4</SUB>HCO<SUB>3</SUB> + 20% ACN (pH 8.2) produced the highest recovery rate of LMPP. To validate the recovery of cut off membrane (COM) obtained using the urea buffer system, 27 different 30 kDa COMs were used to prepare the LMPP sample which were then subjected to 1-D SDS-PAGE. Statistical analysis showed that the buffer system with COM produced a consistent the recovery of LMPP. In addition, 2-DE analysis was also conducted to determine the relative intensity of each protein spot. When molecular weight ranges over 30 kDa and under 30 kDa were evaluated, 953 and 587 protein spots were observed in the gels, respectively, resulting in a total of 1540 protein spots being resolved. Identification of the major proteins were then performed using a nano-LC/MS system comprised of an HPLC system and an ESI-quadrupole IT MS equipped with a nano-ESI source.</P>

The mental health of medical students in Daegu during the 2020 COVID-19 pandemic

Sanghee Yeo,Eunkyung Choi,Jungmin Kim,Seung-Hee Won 한국의학교육학회 2023 Korean journal of medical education Vol.35 No.2

Purpose: In February 2020, the first outbreak of coronavirus disease 2019 (COVID-19) occurred in Daegu, South Korea, and confirmed cases increased sharply, sparking intense anxiety among residents. This study analyzed the data of a mental health survey on students enrolled at a medical school located in Daegu in 2020. Methods: An online survey was administered to 654 medical school students (pre-medical course: 220 students, medical course: 434 students) from August to October 2020, with 61.16% (n=400) valid responses. The questionnaire included items about COVID-19-related experiences, stress, stress resilience, anxiety, and depression. Results: Of the survey participants, 15.5% had experienced unbearable stress, with the most significant stress factors (in descending order) being limited leisure activities, unusual experiences related to COVID-19, and limited social activities. Approximately 28.8% reported psychological distress, and their most experienced negative emotions were helplessness, depression, and anxiety (in descending order). The mean Beck Anxiety Inventory and Beck Depression Inventory-II scores were 2.44 and 6.08, respectively, both within normal ranges. Approximately 8.3% had mild or greater anxiety, and 15% had mild or greater depression. For students under psychological distress, the experience of unbearable stress before COVID-19 affected anxiety (odds ratio [OR], 0.198; p<0.05), and having an underlying condition affected depression (OR, 0.190; p<0.05). With respect to their psychological distress during August–October 2020 compared with that during February–March 2020 (2 months from the initial outbreak), anxiety stayed the same while depression increased and resilience decreased at a statistically significant level. Conclusion: It was found that some medical students were suffering from psychological difficulties related to COVID-19, and there were several risk factors for them. This finding suggests that medical schools need to not only develop academic management systems but also provide programs that can help students manage their mental health and emotions in preparation for an infectious disease pandemic.

Influence of Alkyl Side Chain on the Crystallinity and Trap Density of States in Thiophene and Thiazole Semiconducting Copolymer Based Inkjet-Printed Field-Effect Transistors

Lee, Jiyoul,Chung, Jong Won,Jang, Jaeman,Kim, Do Hwan,Park, Jeong-Il,Lee, Eunkyung,Lee, Bang-Lin,Kim, Joo-Young,Jung, Ji Young,Park, Joon Seok,Koo, Bonwon,Jin, Yong Wan,Kim, Dae Hwan American Chemical Society 2013 Chemistry of materials Vol.25 No.9

<P>The influence of alkyl side chains on the crystallinity of semiconducting copolymer films and their sub-bandgap density-of-states (DOS), the latter being closely related to the stability and the device performance of organic field-effect transistors (OFETs), is investigated. Three different poly(hexathiophene-alt-bithiazole) (PHTBTz) based polymer semiconductors, with identical backbones but different side chain positions and lengths, were synthesized. The crystallinity examined by grazing incidence X-ray diffraction (GIXRD) strongly depends on the number, position, and length of each type of alkyl side chain attached to the thiophene and thiazole copolymer backbones. Also, the sub-bandgap trap DOS distributions were extracted by performing multiple-frequency capacitance–voltage (MF-CV) spectroscopy on the field effect devices. The relationship between film crystallinity and trap DOS in the field-effect transistors can be interpreted in terms of the complex interplay between the number, position, and length of each alkyl side chain for efficient π–π stacking. In particular, the number and position of the alkyl side chain attached to the polymer backbone significantly affects the device performance. Poly(tetryloctylhexathiophene-alt-dioctylbithiazole) (PHTBTz-C8) exhibits the best electrical performance among the different semiconductors synthesized, with a relatively low bulk trap density of ∼2.0 × 10<SUP>20</SUP> cm<SUP>–3</SUP> eV<SUP>–1</SUP> as well as reasonable hole mobility of ∼0.25 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>. The microstructural analyses of this organic material strongly suggest that the short π–π stacking distance induces strong interaction between adjacent polymer backbones, which in turn results in enhanced electrical properties.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2013/cmatex.2013.25.issue-9/cm400592b/production/images/medium/cm-2013-00592b_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm400592b'>ACS Electronic Supporting Info</A></P>

금속 범프와 마이크로 채널 액체 냉각 구조를 이용한 소자의 열 관리 연구

원용현,김성동,김사라은경,Won, Yonghyun,Kim, Sungdong,Kim, Sarah Eunkyung 한국마이크로전자및패키징학회 2016 마이크로전자 및 패키징학회지 Vol.23 No.2

An increase in the transistor density of integrated circuit devices leads to a very high increase in heat dissipation density, which causes a long-term reliability and various thermal problems in microelectronics. In this study, liquid cooling method was investigated using straight microchannels with various metal bumps. Microchannels were fabricated on Si wafer using deep reactive ion etching (DRIE), and Ag, Cu, or Cr/Au/Cu metal bumps were placed on Si wafer by a screen printing method. The surface temperature of liquid cooling structures with various metal bumps was measured by infrared (IR) microscopy. For liquid cooling with Cr/Au/Cu bumps, the surface temperature difference before and after liquid cooling was $45.2^{\circ}C$ and the power density drop was $2.8W/cm^2$ at $200^{\circ}C$ heating temperature. 집적회로(Integrated Circuit) 소자의 트랜지스터(transistor) 밀도 증가는 소자에서 발생하는 열 방출(heat dissipation)의 급격한 상승을 초래하여 열 문제를 발생시키고, 이는 소자의 성능과 열적 신뢰성에 영향을 크게 미친다. 열문제의 해결방안 중 본 연구에서는 냉매를 이용한 액체 냉각방법을 연구하였으며, 실리콘 웨이퍼에 관통실리콘비아(through Si via)와 마이크로 채널(microchannel)을 딥 반응성 이온 애칭(deep reactive ion etching)로 구현한 후 유리기판과 어노딕본딩을 통하여 액체 냉각 구조를 제작하였다. 제작된 마이크로 채널 위에 Ag, Cu 또는 Cr/Au/Cu bump를 스크린프린팅(screen printing) 방법으로 형성하였고, 범프의 유무를 통해 액체 냉각 전후의 냉각 모듈의 실리콘 표면온도의 변화를 적외선현미경으로 분석하였다. Cr/Au/Cu bump가 탑재된 액체 냉각 모듈의 경우 가열온도 $200^{\circ}C$에서 냉각 전후의 실리콘 표면 온도 차이는 약 $45.2^{\circ}C$이고, 전력밀도 감소는 약 $2.8W/cm^2$ 이었다.