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Low-temperature wafer-scale growth of MoS<sub>2</sub>-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>
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>
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>
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.
자동변속기 토크컨버터 록업 및 연비 성능 시뮬레이터 개발
김태성(Taesung Kim),김남두(Namdoo Kim),장재덕(Jaeduk Jang),김현수(Hyunsoo Kim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper, a AMESim vehicle performance simulator is developed for automatic transmission with torque converter. Using the simulator lock-up and slip control area of the torque converter derived for a given torque converter. It is found that the fuel economy by the simulation is in good accordance with the test results which demonstrates the validity of the simulator. It is also found that the fuel economy can be improved approximately 3% in case of slip control of the lock-up clutch. It is expected developed in this paper can be used to design and evaluate the performance of the lock-up clutch and torque converter for automatic transmission vehicle.