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( Jeonghwan Lee ),( Yong Chul Kim ),( Soie Kwon ),( Lilin Li ),( Sohee Oh ),( Do Hyoung Kim ),( Jung Nam An ),( Jang-hee Cho ),( Dong Ki Kim ),( Yong-lim Kim ),( Yun Kyu Oh ),( Chun Soo Lim ),( Yon Su 대한신장학회 2020 Kidney Research and Clinical Practice Vol.39 No.4
Background: The effect of each health-related quality of life (HRQOL) component on hemodialysis prognosis has not been well studied. We aimed to investigate the clinical factors associated with HRQOL and the effect of HRQOL after dialysis initiation on long-term survival in an Asian population. Methods: A total of 568 hemodialysis patients were included from a nationwide prospective cohort study. HRQOL was evaluated using the Kidney Disease Quality of Life (KDQOL) Short FormTM 1.3 at 3 months after dialysis initiation. The effect of each KDQOL item score on mortality was analyzed. Multivariable Cox analysis was performed after adjusting for age, sex, modified Charlson comorbidity index, and causes of primary kidney disease. Results: Old age, diabetes mellitus, high comorbidities, and low serum albumin levels were associated with poor physical health status. Decreased urine output was associated with both poor physical and mental health status. The scores of 3 indices in the kidney disease domain (effect of kidney disease, social support, and dialysis staff encouragement) showed significant associations with mortality, as did the 3 indices (physical function, physical role limitation, and body pain) in the physical health domain. Neither the 4 indices in the mental health domain nor the mental composite score showed a significant association with mortality. However, a high physical composite score was associated with decreased overall patient mortality (P = 0.003). The effect of physical composite score on survival was prominent among young or middle-aged groups. Conclusion: Poor physical health status 3 months after hemodialysis start correlates significantly with overall mortality.
Lim, Seokjae,Sung, Changhyuck,Kim, Hyungjun,Kim, Taesu,Song, Jeonghwan,Kim, Jae-Joon,Hwang, Hyunsang IEEE 2018 IEEE electron device letters Vol.39 No.2
<P>In this letter, we demonstrate the conductive-bridging RAM (CBRAM) with excellent multi-level cell (MLC) and linear conductance characteristics for an artificial synaptic device of neuromorphic systems. Our findings show that inherent characteristics of CBRAM can achieve the linear conductance and MLC characteristics as a product of an integer unit of the conductance. However, uncontrolled metal-ion injection into the switching layer results in a significant degradation of device uniformity, leading to degradation in the classification accuracy. Thus, we introduce a multi-layer CBRAM configuration (Cu/HfO<SUB>2</SUB>/Ta/Cu<SUB>2</SUB>S/W) to control the ionic motion in electrolytes. As a result of device engineering, highly improved classification accuracy is achieved using CIFAR-10 data set.</P>
Injong Lim,Jeonghwan Lee,Sang-Myung Lee 보안공학연구지원센터 2016 International Journal of Software Engineering and Vol.10 No.12
Public research institutes take major role in creating breakthrough technology development but most cases, fail to successfully commercialize it. This is very critical symptom in Korea where the government R&D expenditure is among top in the world, but its money value of commercialization is very low. In this study, we studied all Korean public research institutes to evaluate the efficiency of their technology development and technology transfer, showing the wide gap of two activities. In order to properly measure the efficiency, we make full use of input and output variables such as research/TLO human resources and expense, and research outputs such as patents and royalty revenue. In summary, we show that, in order to efficiently manage government-supported R&D, it is necessary to maximize the efficiency both for technology development and technology transfer of public research institutes.
Self-Limited CBRAM With Threshold Selector for 1S1R Crossbar Array Applications
Song, Jeonghwan,Woo, Jiyong,Lim, Seokjae,Chekol, Solomon Amsalu,Hwang, Hyunsang IEEE 2017 IEEE electron device letters Vol.38 No.11
<P>In this letter, we demonstrate a self-limited conductive-bridging random accessmemory (CBRAM) that removes the necessity for external current compliance in a one selector-one resistor (1S1R) architecture. The standard Ge2Sb2Te5 (GST) is used as a CBRAM switching layer. In addition, Te-rich GST is also considered. Their performance is then compared. Both samples exhibit self-limited on-current characteristics, and the on-currents of the standard GST and Te-rich GST are similar to 300 and similar to 20 mu A, respectively. The observed self-limited characteristics are caused by the Te in the GST layer because in the presence of Te, Cu tends to form a more stable CuTe phase that restrict Cu filament growth. Furthermore, to confirm the feasibility of crossbar array applications, the 1S1R device is evaluated using a Ag/TiO2-based threshold selector device reported in our previous work. Hence, we confirm leakage current reduction, a uniform resistance distribution, and stable retention characteristics in the 1S1R configuration with no external current compliance.</P>
도정환(Jeonghwan Do),이성민(Seong-Min Lee),전유림(Yurim Jeon),최형준(Hyungjoon Choi),정희원(Heewon Jeong),지상연(Sangyeon Ji),김철웅(Cheulwoong Kim),임석희(Seokhee Lim) 한국추진공학회 2023 한국추진공학회 학술대회논문집 Vol.2023 No.5
In this paper, the configuration of the propulsion system of the vertical take-off and landing demonstrator(VTVL) and the pressure control concept and design method applied to the VTVL are introduced, and the results of the cold flow test using liquid nitrogen are analyzed. The propulsion system of the VTVL uses liquid oxygen and liquid natural gas as propellants, and a gaseous nitrogen pressurization system is applied. When the propellant is supplied, an appropriate amount of pressurized gas is supplied to maintain the pressure in the propellant tank at a certain required pressure. To control the supply rate of pressurized gas, an assembly block composed of solenoid valves and orifices was developed, and its effectiveness was confirmed through analysis of the liquid nitrogen flow test results.
Hyunseok Lim(임현석),Jeonghwan Gwak(곽정환) 한국컴퓨터정보학회 2021 韓國컴퓨터情報學會論文誌 Vol.26 No.4
이상 객체란 일반적이고 평범한 행동을 취하는 객체가 아닌 비정상적이고 흔하지 않은 행동을 하여 관찰이나 감시 · 감독을 필요로 하는 사람, 물체, 기계 장치 등을 뜻한다. 이를 사람의 지속적인 개입 없이 인공지능 알고리즘을 통해 탐지하기 위해서 광학 흐름 기법을 활용한 시간적 특징의 특이도를 관찰하는 방법이 많이 활용되고 있으며, 이 기법은 정해진 표현 범위가 없는 수많은 이상 행동을 식별하기에 적합하다. 본 연구에서는 생성적 적대 신경망(Generative Adversarial Network, GAN)으로 입력 영상 프레임을 광학 흐름 영상으로 변환하는 알고리즘을 학습시켜 비정상적인 상황을 식별한다. 특히 생성적 적대 신경망 모델이 입력 영상에 대한 중요한 특징 정보를 학습하고, 그 외 불필요한 이상치를 제외시키기 위한 전처리 과정과 학습 후 테스트 데이터셋에서 식별 정확도를 높이기 위한 후처리 과정을 고도화하여 전체적인 모델의 이상 행동 식별 성능을 향상시키는 기법을 제안한다. 이상 행동을 탐지하기 위한 학습 데이터셋으로 UCSD Pedestrian, UMN Unusual Crowd Activity를 활용하였으며, UCSD Ped2 데이터셋에서 프레임 레벨 AUC 0.9450, EER 0.1317의 수치를 보이며 이전 연구에서 도출된 성능 지표 대비 성능 향상이 확인되었다. An abnormal object refers to a person, an object, or a mechanical device that performs abnormal and unusual behavior and needs observation or supervision. In order to detect this through artificial intelligence algorithm without continuous human intervention, a method of observing the specificity of temporal features using optical flow technique is widely used. In this study, an abnormal situation is identified by learning an algorithm that translates an input image frame to an optical flow image using a Generative Adversarial Network (GAN). In particular, we propose a technique that improves the pre-processing process to exclude unnecessary outliers and the post-processing process to increase the accuracy of identification in the test dataset after learning to improve the performance of the model’s abnormal behavior identification. UCSD Pedestrian and UMN Unusual Crowd Activity were used as training datasets to detect abnormal behavior. For the proposed method, the frame-level AUC 0.9450 and EER 0.1317 were shown in the UCSD Ped2 dataset, which shows performance improvement compared to the models in the previous studies.
1D/3D를 연계한 중소형 트럭 엔진룸의 냉각성능에 관한 해석적 고찰
최정환(Jeonghwan Choi),김민호(Minho Kim),박종찬(Jongchan Park),임정환(Junghwan Lim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recently, the automakers pay attention to new diesel engine technologies such as cooled exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) to meet the emission regulations. Since these additional components for EGR, SCR cause the increase of heat rejection rate in engine, it leads into a new cooling system design to meet the cooling performance. In this study, 1D and 3D simulation have been performed simultaneously to visualize the cooling air flow field in an engine compartment and to obtain the information for adjustment of the 1D network model. The feasibility of using the 1D network simulation in the initial design stage is studied to find out its validity and limitation in cooling module design, through comparison with the results of the vehicle test and the 3D CFD analysis. As a result of this study, it is found out that the 10 network model can efficiently predict reliable results at the early design stage.