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>

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>

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.

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

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’.

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.

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.

액랭식 마이크로채널 시스템 내 냉매와 범프의 열 제거 효과에 대한 연구

원용현,김성동,김사라은경,Won, Yonghyun,Kim, Sungdong,Kim, Sarah Eunkyung 한국마이크로전자및패키징학회 2017 마이크로전자 및 패키징학회지 Vol.24 No.2

소자의 트랜지스터 밀도가 급속히 높아짐에 따라 소자 내부에서 발생하는 열 유속(heat flux) 또한 빠르게 증가하고 있다. 소자의 고열 문제는 소자의 성능과 신뢰성 감소에 크게 영향을 미친다. 기존의 냉각방법들은 이러한 고열문제를 해결하기 위해선 한계점에 다다랐고, 그 대안으로 liquid heat pipe, thermoelectric cooler, thermal Si via, 등 여러 냉각방법이 연구되고 있다. 본 실험에서는 직선형 마이크로채널과 TSV(through Si via)를 이용한 액체 냉각시스템을 연구하였다. 두 종류의 냉매(DI water와 ethylene glycol(70 wt%))와 3 종류의 금속 범프(Ag, Cu, Cr/Au/Cu)의 영향을 분석하였으며, 대류, 복사 및 액체 냉각으로 인한 총 열 유속을 계산하여 비교하였다. 냉각 전후의 냉각시스템의 표면온도는 적외선현미경을 통해 측정하였고, 마이크로채널 내 액체 흐름은 형광현미경을 이용하여 측정하였다. 총 열 유속은 ethylene glycol(70 wt%)의 경우 가열 온도 $200^{\circ}C$에서 $2.42W/cm^2$로 나타났으며 대부분 액체 냉각 효과에 의한 결과로 확인되었다. As transistor density increases rapidly, a heat flux from IC device rises at fast rate. Thermal issues raised by high heat flux cause IC's performance and reliability problems. To solve these thermal management problems, the conventional cooling methods of IC devices were reached their thermal limit. As a result, alternative cooling methods such as liquid heat pipe, thermoelectric cooler, thermal Si via and etc. are currently emerging. In this paper microchannel liquid cooling system with TSV was investigated. The effects of 2 coolants (DI water and ethylene glycol 70 wt%) and 3 metal bumps (Ag, Cu, Cr/Au/Cu) on cooling performance were studied, and the total heat flux of various coolant and bump cases were compared. Surface temperature of liquid cooling system was measured by infrared microscopy, and liquid flowing through microchannel was observed by fluorescence microscope. In the case of ethylene glycol 70 wt% at $200^{\circ}C$ heating temperature, the total heat flux was $2.42W/cm^2$ and most of total heat flux was from liquid cooling effect.

마이크로 채널 디자인에 따른 온 칩 액체 냉각 연구

원용현,김성동,김사라은경,Won, Yonghyun,Kim, Sungdong,Kim, Sarah Eunkyung 한국마이크로전자및패키징학회 2015 마이크로전자 및 패키징학회지 Vol.22 No.4

전자소자의 다기능, 고밀도, 고성능, 그리고 소형화는 전자 패키지 기술에 초미세 피치 플립 칩, 3D 패키지, 유연 패키지, 등 새로운 기술 패러다임 전환을 가져왔으며, 이로 인해 패키지 된 칩의 열 관리는 소자의 성능을 좌우하는 중요한 요소로 대두되고 있다. Heat sink, heat spreader, TIM, 열전 냉각기, 등 많은 소자 냉각 방법들 중 본 연구에서는 냉매를 이용한 on-chip 액체 냉각 모듈을 Si 웨이퍼에 제작하고, 마이크로 채널 디자인에 따른 냉각 효과를 분석하였다. 마이크로 채널은 딥 반응성 이온 에칭을 이용하여 형성하였고, 3 종류 디자인(straight MC, serpentine MC, zigzag MC)으로 제작하여 마이크로 채널 디자인이 냉각 효율에 미치는 영향을 관찰하였다. 가열온도 $200^{\circ}C$, 냉매 유동속도 150 ml/min의 경우에서 straight MC가 약 $44^{\circ}C$의 높은 냉각 전후의 온도 차를 보였다. 냉매의 흐름과 상 변화는 형광현미경으로 관찰하였으며, 냉각 전후의 온도 차는 적외선현미경을 이용하여 분석하였다. The demand for multi-functionality, high density, high performance, and miniaturization of IC devices has caused the technology paradigm shift for electronic packaging. So, thermal management of new packaged chips becomes a bottleneck for the performance of next generation devices. Among various thermal solutions such as heat sink, heat spreader, TIM, thermoelectric cooler, etc. on-chip liquid cooling module was investigated in this study. Micro-channel was fabricated on Si wafer using a deep reactive ion etching, and 3 different micro-channel designs (straight MC, serpentine MC, zigzag MC) were formed to evalute the effectiveness of liquid cooling. At the heating temperature of $200^{\circ}C$ and coolant flow rate of 150ml/min, straight MC showed the high temperature differential of ${\sim}44^{\circ}C$ after liquid cooling. The shape of liquid flowing through micro-channel was observed by fluorescence microscope, and the temperarue differential of liquid cooling module was measuremd by IR microscope.