Clinical Characteristics and Outcomes of COVID-19 Cohort Patients in Daegu Metropolitan City Outbreak in 2020

Kim Shin-Woo,Kim Seung-Mee,Kim Yu Kyung,Kim Jong-yeon,Lee Yu-Mi,Kim Bong-Ok,Hwangbo Suhyun,Park Taesung 대한의학회 2021 Journal of Korean medical science Vol.36 No.1

Background: A coronavirus disease 2019 (COVID-19) outbreak started in February 2020 and was controlled at the end of March 2020 in Daegu, the epicenter of the coronavirus outbreak in Korea. The aim of this study was to describe the clinical course and outcomes of patients with COVID-19 in Daegu. Methods: In collaboration with Daegu Metropolitan City and Korean Center for Diseases Control, we conducted a retrospective, multicenter cohort study. Demographic, clinical, treatment, and laboratory data, including viral RNA detection, were obtained from the electronic medical records and cohort database and compared between survivors and non-survivors. We used univariate and multi-variable logistic regression methods and Cox regression model and performed Kaplan–Meier analysis to determine the risk factors associated with the 28-day mortality and release from isolation among the patients. Results: In this study, 7,057 laboratory-confirmed patients with COVID-19 (total cohort) who had been diagnosed from February 18 to July 10, 2020 were included. Of the total cohort, 5,467 were asymptomatic to mild patients (77.4%) (asymptomatic 30.6% and mild 46.8%), 985 moderate (14.0%), 380 severe (5.4%), and 225 critical (3.2%). The mortality of the patients was 2.5% (179/7,057). The Cox regression hazard model for the patients with available clinical information (core cohort) (n = 2,254) showed the risk factors for 28-day mortality: age > 70 (hazard ratio [HR], 4.219, P = 0.002), need for O2 supply at admission (HR, 2.995; P = 0.001), fever (> 37.5°C) (HR, 2.808; P = 0.001), diabetes (HR, 2.119; P = 0.008), cancer (HR, 3.043; P = 0.011), dementia (HR, 5.252; P = 0.008), neurological disease (HR, 2.084; P = 0.039), heart failure (HR, 3.234; P = 0.012), and hypertension (HR, 2.160; P = 0.017). The median duration for release from isolation was 33 days (interquartile range, 24.0–46.0) in survivors. The Cox proportional hazard model for the long duration of isolation included severity, age > 70, and dementia. Conclusion: Overall, asymptomatic to mild patients were approximately 77% of the total cohort (asymptomatic, 30.6%). The case fatality rate was 2.5%. Risk factors, including older age, need for O2 supply, dementia, and neurological disorder at admission, could help clinicians to identify COVID-19 patients with poor prognosis at an early stage.

Low-temperature wafer-scale growth of MoS₂-graphene heterostructures

Kim, Hyeong-U,Kim, Mansu,Jin, Yinhua,Hyeon, Yuhwan,Kim, Ki Seok,An, Byeong-Seon,Yang, Cheol-Woong,Kanade, Vinit,Moon, Ji-Yun,Yeom, Geun Yong,Whang, Dongmok,Lee, Jae-Hyun,Kim, Taesung Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.470 No.-

<P><B>Abstract</B></P> <P>In this study, we successfully demonstrate the fabrication of a MoS<SUB>2</SUB>-graphene heterostructure (MGH) on a 4 inch wafer at 300 °C by depositing a thin Mo film seed layer on graphene followed by sulfurization using H<SUB>2</SUB>S plasma. By utilizing Raman spectroscopy and high-resolution transmission electron microscopy, we have confirmed that 5–6 MoS<SUB>2</SUB> layers with a large density of sulfur vacancies are grown uniformly on the entire substrate. The chemical composition of MoS<SUB>2</SUB> on graphene was evaluated by X-ray photoelectron spectroscopy, which confirmed the atomic ratio of Mo to S to be 1:1.78, which is much lower than the stoichiometric value of 2 from standard MoS<SUB>2</SUB>. To exploit the properties of the nanocrystalline and defective MGH film obtained in our process, we have utilized it as a catalyst for hydrodesulfurization and as an electrocatalyst for the hydrogen evolution reaction. Compared to MoS<SUB>2</SUB> grown on an amorphous SiO<SUB>2</SUB> substrate, the MGH has smaller onset potential and Tafel slope, indicating its enhanced catalytic performance. Our practical growth approach can be applied to other two-dimensional crystals, which are potentially used in a wide range of applications such as electronic devices and catalysis.</P> <P><B>Highlight</B></P> <P> <UL> <LI> Practical growth for 2D MoS<SUB>2</SUB>-graphene heterostructure (MGH) was introduced. </LI> <LI> Low-temperature sulfurization of Mo thin film was realized by H<SUB>2</SUB>S plasma. </LI> <LI> As-grown MoS<SUB>2</SUB> film on graphene naturally contains large number of active sites. </LI> <LI> The MGH was shown enhanced electrocatalytic performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Biomarker Development for Intraductal Papillary Mucinous Neoplasms Using Multiple Reaction Monitoring Mass Spectrometry

Kim, Yikwon,Kang, MeeJoo,Han, Dohyun,Kim, Hyunsoo,Lee, KyoungBun,Kim, Sun-Whe,Kim, Yongkang,Park, Taesung,Jang, Jin-Young,Kim, Youngsoo American Chemical Society 2016 JOURNAL OF PROTEOME RESEARCH Vol.15 No.1

<P>Intraductal papillary mucinous neoplasm (IPMN) is a common precursor of pancreatic cancer (PC). Much clinical attention has been directed toward IPMNs due to the increase in the prevalence of PC. The diagnosis of IPMN depends primarily on a radiological examination, but the diagnostic accuracy of this tool is not satisfactory, necessitating the development of accurate diagnostic biomarkers for IPMN to prevent PC. Recently, high-throughput targeted proteomic quantification methods have accelerated the discovery of biomarkers, rendering them powerful platforms for the evolution of IPMN diagnostic biomarkers. In this study, a robust multiple reaction monitoring (MRM) pipeline was applied to discovery and verify IPMN biomarker candidates in a large cohort of plasma samples. Through highly reproducible MRM assays and a stringent statistical analysis, 11 proteins were selected as IPMN marker candidates with high confidence in 184 plasma samples, comprising a training (n = 84) and test set (n = 100). To improve the discriminatory power, we constructed a six-protein panel by combining marker candidates. The multimarker panel had high discriminatory power in distinguishing between IPMN and controls, including other benign diseases. Consequently, the diagnostic accuracy of IPMN can be improved dramatically with this novel plasma-based panel in combination with a radiological examination.</P>

Effects of Ceria Abrasive Particle Size Distribution below Wafer Surface on In-Wafer Uniformity during Chemical Mechanical Polishing Processing

Kim, Hojoong,Yang, Ji Chul,Kim, Myungjoon,Oh, Dong-won,Lee, Chil-Gee,Kim, Sang-Yong,Kim, Taesung The Electrochemical Society 2011 Journal of the Electrochemical Society Vol.158 No.6

Development of particle characteristics diagnosis system for nanoparticle analysis in vacuum

Kim, Dongbin,Mun, Jihun,Kim, HyeongU,Yun, Ju-Young,Kim, Yong-Ju,Kim, TaeWan,Kim, Taesung,Kang, Sang-Woo American Institute of Physics 2016 Review of scientific instruments Vol.87 No.2

Measurement of the Particle Current Changes Associated with the Flatness of Deflector Mesh Surface in Particle Beam Mass Spectrometer System

Kim, Dongbin,Kim, TaeWan,Jin, Yinhua,Mun, Jihun,Lim, In-Tae,Kim, Ju-Hwang,Kim, Taesung,Kang, Sang-Woo The Korean Vacuum Society 2016 Applied Science and Convergence Technology Vol.25 No.2

The surface flatness of metal meshes in a deflector of particle beam mass spectrometer (PBMS) required ideally flat, and this can specify the particle trajectories which goes through the detector. In this research, charged particle current was measured using the different surface roughness deflectors. NaCl particles were generated monodispersed in its size by using differential mobility analyzer and the whole processes were followed the way calibrating PBMS. The results indicate that the mesh surface morphology in the deflector can affect to the particle size and the concentration errors, and sensitivity of PBMS.

Numerical study on heat transfer and pressure drop in laminar-flow multistage mini-channel heat sink

Kim, Yeongseok,Kim, Myungjoon,Ahn, Chisung,Kim, Hyeong U.,Kang, Sang-Woo,Kim, Taesung Elsevier 2017 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.108 No.1

<P><B>Abstract</B></P> <P>Mini-channel has been more studied recently than micro-channel to optimize the heat emission and pressure drop by regulating the channel size and length. In this work, a multistage mini-channel heat sink using water coolant was designed to obtain a larger cooling rate in a small area with a lower pressure drop. To confirm the performance of the structure, we conducted numerical simulations under laminar and single-phase conditions. The diameter and length of the channel were 2 and 530mm, respectively. From the simulation, the local convection coefficient, coolant temperature, channel-wall temperature, effectiveness, and pressure drop were analyzed in relation to the mass flux, heat-source temperature, and number of stage stacks. To obtain valid simulation results on the heat transfer, we used well-matched conventional correlation. The result of the pressure drop was compared with the experimental result to confirm the validity of the hydrodynamic model. The simulation result shows that the maximum cooling rate was 40W/cm<SUP>2</SUP> at a pressure drop of 1383Pa in a quintuple-stage model. However, the triple-stage structure had the best effectiveness of 0.83 under the same simulation conditions. The pressure drop of the multistage structure was higher than that of the single-stage structure. However, the increase of the total pressure drop was small as against the increase of the cooling rate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A multistage mini-channel heat sink is proposed to increase the cooling rate. </LI> <LI> Numerical simulations were done to verify the multistage mini-channel performance. </LI> <LI> The optimum structure is the triple stage that yields the largest heat emission among the multistage mini-channel. </LI> <LI> Multistage structure could improve the cooling rate with the small increase of the pressure drop. </LI> </UL> </P>

Na 첨가량에 따른 CIGS 광흡수층의 결정성 변화에 관한 연구

김대성(Kim, Daesung),김재웅(Kim, Chaewoong),김대경(Kim, Daekyong),이덕훈(Lee, Duckhoon),김태성(Kim, Taesung) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

CIS(CuInSe2)계 화합물 태양전지는 높은 광흡수계수와 열적 안정성으로 고효율 태양전지 제조가 가능하여 태양전지용 광흡수층으로 매우 이상적이다. 미국 NREL에서는 이러한 CIGS 태양전지를 Co-evaporation 방법으로 제조 20%이상의 에너지 변환 효율을 달성하였다고 보고하였다. CIGS 태양전지의 경우 기존의 유리 기판 대신 유연한 철강 기판을 사용해 태양전지를 flexible하게 제조 할 수 있다는 장점이 있다. 이러한 flexible 태양전지의 경우 기존의 rigid 태양전지의 적용분야 뿐만 아니라 BIPV, 선박, 장난감, 군용, 자동차등 더욱더 많은 분야에 활용이 가능하다. 하지만 flexible 태양전지에 사용되는 철강기판의 경우 기존의 유리 기판인 SLG에 함유되어 있는 Na이 첨가되어 있지 않아 별도의 Na 첨가가 필요하다. Na은 CIGS 광흡수층의 결정을 증가 시키며 태양전지의 전기적 특성을 향상시킨다. 이러한 Na이 없는 경우 효율이 감소한다. 따라서 flexible 태양전지 개발을 위해서는 Na 첨가에 대한 연구가 필수적이다. 본 연구에서는 Na의 증착 순서를 변화시켜서 CIGS 증착 전, 동시증착, CIGS 증착 후로 나누어 CIGS 광흡수층 결정성의 변화를 알아보고자 한다. Na의 두께를 5nm에서 500nm 까지 단계 별로 나누어 실험을 실시하였다. 이때 CIGS 광흡수층은 미국의 NREL과 같은 3 stage 방식을 이용하였다. 1st stage의 시간은 15분으로 고정하였으며 기판온도는 약 300?C로 고정 하였다. 2nd stage는 실시간 온도 감지 장치를 이용하여 Cu와 In+Ga의 조성비가 1:1이 되는 시간을 기준으로 Cu의 조성을 30%더 높게 조절하였으며 기판 온도는 약 640?C로 고정 후 실험을 실시하였다. 3rd stage의 경우 Cu poor 조성으로 조절하기 위해 모든 조건을 10분으로 고정 후 실험을 실시하였다. 기판은 Na의 영향만을 비교하기위하여 Na이 첨가되어있지 않은 corning glass를 사용하였다. 후면 전극으로 약 1{mu}m 두께의 Mo을 DC Sputtering 방법을 이용하여 증착 하였다. 각각의 Na 두께에 따른 CIGS 광흡수층의 특성을 분석하기 위해 FE-SEM, XRD 분석을 실시하였다.

Na이 CIGS 박막 태양전지에 미치는 영향에 관한 연구

김재웅(Kim, Chaewoong),김대성(Kim, Daesung),김태성(Kim, Taesung),김진혁(Kim, Jinhyok) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06

CIS(CuInSe2)계 화합물 태양전지는 높은 광흡수계수와 열적 안정성 및 조성 조절을 통한 밴드갭 조절이 용이해 고효율 박막 태양전지로 각광 받고 있다. 또한 CIGS 태양전지는 기존의 유리기판 대신 유연한 기판을 사용해 flexible 태양전지 제조가 가능하다. 이러한 유연기판은 보통 stainless steel과 같은 금속 기판이 많이 사용되는데 기존의 soda-lime glass 기판과는 달리 금속기판에는 Na이 첨가되어 있지 않아 별도의 Na첨가를 필요로 한다. Na은 CIGS 흡수층의 조성조절을 용이하게 하여 태양전지의 변환 효율을 향상시키는 역할을 한다. 본 연구에서 기판은 Na이 첨가되어있지 않은 corning glass를 사용 하였으며 NaF를 이용해 Mo가 증착된 기판에 NaF의 두께를 달리하며 증착해 CIGS 흡수층의 grain 사이즈를 비교 하였으며 그 후 태양전지 소자를 제조해 광전특성을 분석하였다. 후면 전극으로 약60nm 두께의 Mo를 DC Sputtering 방법을 이용해 증착 하였다. buffer층으로는 약 50nm의 CdS층을 CBD방법을 이용하여 제조 하였으며 TCO 층으로 약 50nm의 i-ZnO와 약 450nm의 Al-ZnO를 RF Sputtering방법으로 증착 하였다. 마지막으로 앞면 전극으로 약 1{mu}m의 Al을 Thermal Evaporation방법으로 증착하였다. 태양전지 소자의 면적은 0.49cm²로 효율을 비교 분석하였다.

Frictional Characteristics of Nanoporous SiO2/TiO2 Film with Treated Surface by Chemical Mechanical Polishing (CMP)

Hojoong Kim,Daekwang Woo,Ji Hun Kim,Min Suk Kang,Jeong Kuk Shon,Ji Man Kim,Young Ze Lee,Taesung Kim 한국표면공학회 2008 한국표면공학회 학술발표회 초록집 Vol.2008 No.-