Impact of health-related quality of life on survival after dialysis initiation: a prospective cohort study in Korea

( 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.

시계열 예측을 사용한 버스 잔여좌석 예측 시스템

임정환(JeongHwan Lim),박성수(SeongSu Park),고승범(SeungBeom Go),김준태(JunTae Kim),김동호(DongHo Kim) 한국정보과학회 2017 한국정보과학회 학술발표논문집 Vol.2017 No.06

CMOS compatible low-power volatile atomic switch for steep-slope FET devices

Lim, Seokjae,Yoo, Jongmyung,Song, Jeonghwan,Woo, Jiyong,Park, Jaehyuk,Hwang, Hyunsang American Institute of Physics 2018 Applied Physics Letters Vol.113 No.3

Improved Synapse Device With MLC and Conductance Linearity Using Quantized Conduction for Neuromorphic Systems

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>

산불 피해지 복원 방법이 임분 내 미세 기후에 미치는 영향

김정환 ( Jeonghwan Kim ),임주훈 ( Joohoon Lim ),박찬우 ( Chanwoo Park ),권진오 ( Jino Kwon ),최형태 ( Hyungtae Choi ) 한국농림기상학회 2015 한국농림기상학회지 Vol.17 No.3

본 연구는 산불 피해지에서 복원 방법 및 수종의 구성에 따라 미세 기후가 어떻게 변하는지에 관한 연구는 거의 이루어진 바 없어 산불 피해지에서 복원방법 및 임분의 구성에 따라 임분 내 기상 패턴이 어떻게 변화하는지에 대해 구명하고자 수행되었다. 본연구에서 사용된 독립 변수로 임분을 구성하는 수종의 종류와 생장, 임분 밀도, 그리고 피복율이며, 이에 따른 종속 변수로는 임분 내 광량, 기온, 습도, 토양 온도, 그리고 토양 수분 함량이었다. 기상 조건은 대부분 광 조건에 영향을 받는 종속 변수이나, 임분을 구성하는 수목의 생장과 피복률에도 변화하는 것으로 나타났다. 임분 내 습도는 임분 밀도와, 임분 내 기온과 수목의 수고와 음(-)의 상관 관계에 있는 것으로 나타나 임분 밀도와 수목의 생장이 증가할수록 임분 내부의 기온과 습도는 상대적으로 감소하는 경향을 보였다. 그러나 임분의 발달은 대부분 미세 기후의 전체 평균보다는 변동계수와 같은 편차를 줄이는 형태로 더 큰 영향을 주었으며, 수관 층의 수고와 임분 내 광량과 직접적인 관계에 있는 것을 감안하면(R2=0.87), 임분의 구조는 광량에는 직접적인 영향을, 다른 미세 기후에는 간접적인 영향을 준 것으로 사료된다. 한편 변동계수의 경우 삼척 지역이 고성 지역보다 상대적으로 높은 값을 보였으며, 수목의 생장에 따라 감소하는 경향을 보였다. 따라서 산불 발생 이후 시간 경과에 따라 상대적으로 안정된 상태를 지니는 것으로 해석되었다. 그러나, 현재 단계에서는 산불 피해 이후 숲의 발달에 따른 임분 내부의 기상 조건의 변화상을 뚜렷하게 확인하고 일반화하기에는 많은 어려움이 있어 이를위해서는 보다 긴 시간에 걸쳐 많은 지점에서의 기상조건과 임분 현황을 지속적으로 조사되어야 할 것이다. 이후 일반화된 자료를 활용한다면, 임분 구조와의 관계 해석은 물론, 하층 식생 출현 등에 대한 해석에 도움이 될 것으로 기대된다. The study was conducted to determine the effects of forest restoration methods and stand structure on solar radiation, air temperature, relative humidity, soil temperature, and soil water content, based on volume, in forest stand after forest fire. The changes of the micro-climate elements in naturally and artificially restored forest after forest fire were measured in Goseong and Samcheok, Gangwon province. Pinus spp. were commonly appeared in ridges, barren lands or planted areas of the study sites while the other areas were dominated by Quercus spp. In the early stage, trees in the naturally regenerated site grow better than the trees in artificially rehabilitated site. However, the growth ratio rapidly decreased by time passed in natural regeneration area. The environmental conditions (solar radiation, air temperature, relative humidity, soil temperature and soil water content) were significantly different by the regions and the methods (p<.05). However, the coefficients of variations of the environmental conditions were not significantly different at 95% confidence level. As the coverage and tree height in crown layer increased, the relative humidity and soil water content were increased while the temperature and solar radiation were decreased. Especially, the relative humidity, solar radiation, and soil water content were clearly affected by the tree height and coverage ratio (R2 means from 0.628 to 0.924). Even though the data should have collected at least more than 5 years in meteorological analysis, the two year results show some clear relationship between forest structure and microclimate elements.

Generative optical flow based abnormal object detection method using a spatio-temporal translation network

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.

Effects of Liner Thickness on the Reliability of AgTe/TiO₂-Based Threshold Switching Devices

Song, Jeonghwan,Woo, Jiyong,Yoo, Jongmyung,Chekol, Solomon Amsalu,Lim, Seokjae,Sung, Changhyuck,Hwang, Hyunsang Institute of Electrical and Electronics Engineers 2017 IEEE transactions on electron devices Vol.64 No.11

<P>The effects of liner thickness on the reliability of AgTe/TiO2-based threshold switching (TS) devices were investigated. The off-state current of an AgTe/TiO2/Pt TS device was found to be significantly increased by in-diffusion of Ag into the TiO2 layer during the annealing process. Therefore, 3-, 5- and 7-nm TiN liners were introduced and compared to prevent the in-diffusion of Ag. While the 3-nm TiN liner was shown to be incapable of blocking Ag in-diffusion into the TiO2 layer, the 5- and 7-nm liners effectively suppressed in-diffusion and maintained high off-state resistance. However, the TS device with the 7-nm TiN liner exhibited wide threshold voltage distribution and poor endurance characteristics owing to a lack of Ag sources. The TS device with a 5-nm TiN liner, by contrast, was found to have an adequate amount of Ag sources and to demonstrate thermally stable and electrically reliable characteristics. The effects of TiN liner on Ag diffusion were also directly confirmed using energy dispersive spectrometry line profiles, transmission electron microscopy imaging, and mapping analyses.</P>

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.

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>

운전자 부주의로 인한 위험 상황 판단 연구

류정환(Jeonghwan Ryu),김현건(Hyunkun Kim),정의석(Euiseok Jeong),최종기(Jonggi Choi),임세준(Sejoon Lim) 한국자동차공학회 2020 한국자동차공학회 학술대회 및 전시회 Vol.2020 No.11