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Sehun Min,Hyun Kyu Suh 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.1
The objective of this numerical study is to investigate the effect of CO2 mole fraction controlled by simulated-exhaust gas recirculation (EGR) on fuel droplet behavior for simultaneous exhaust emissions reduction in compression ignition engine under early injection conditions. In the simulation, the intake air initial composition was changed to simulate the EGR with changing CO2 mole fraction. To consider early injection conditions, start of energizing timing was changed. The results were analyzed in terms of spray tip penetration, Sauter mean diameter, evaporated fuel ratio, and fuel mass fraction distributions. When CO2 mole fraction increased, spray tip penetration was decreased because the kinetic energy of the injected fuel droplet was reduced by the high density of CO2 and SMD was decreased since the high density of CO2 disturbed the fuel progress, which induced the fuel droplet to have low kinetic energy. In addition, when the start of energizing timing was before top dead center 23 degree and CO2 mole fraction was 20 %, exhaust emissions were expected to simultaneously reduce because the rapidly evaporated fuel by the collision effect promoted the combustion, and it made to evaporate the formed liquid wall film, which may absorb the combustion temperature by the latent heat vaporization.
( Sehun Kim ),( Donghoon Han ),( Jae Hyuk Choi ),( Eun-joo Park ),( Dong Geum Shin ),( Min-kyung Kang ),( Seonghoon Choi ),( Namho Lee ),( Jung Rae Cho ) 대한내과학회 2021 The Korean Journal of Internal Medicine Vol.36 No.0
Background/Aims: Prolonged dual antiplatelet therapy (DAPT) with aspirin and clopidogrel beyond 1 year has been shown to reduce ischemic events at the expense of increased bleeding. However, limited data are available on the clinical significance of platelet reactivity (PR) at 1 year. Methods: We retrospectively identified 331 patients who underwent percutaneous coronary intervention (PCI) and assessed the on-clopidogrel PR using VerifyNow P2Y12 assay at 1 year in a single center. Two hundred eleven patients were on DAPT for > 1 year. The relationship between high on-treatment platelet reactivity (HPR) at 1 year and clinical outcomes beyond 1 year, as well as the longitudinal change in PR was analyzed. Results: At 1 year, 135 (64%) patients showed HPR and 76 (36%) did not. There was a significant increase in ischemic endpoint events, including cardiovascular death, non-fatal myocardial infarction, and stroke/transient ischemic attack in patients with compared to without HPR at 1 year (hazard ratio [HR], 2.68; 95% confidence interval [CI], 1.06 to 6.77; p = 0.036). However, the incidence of any Bleeding Academic Research Consortium bleeding was significantly lower in the HPR group (HR, 0.11; 95% CI, 0.02 to 0.65; p = 0.015). In the longitudinal analysis, PR significantly decreased from post-load to 1 year after index PCI in the non-HPR group. Conversely, the HPR group showed high PR from baseline through 1 year. Conclusions: HPR at 1 year may be a useful surrogate for predicting ischemic and bleeding events in patients on prolonged DAPT. Patients with and without HPR at 1 year showed different patterns of longitudinal change in PR.
( Sehun Kim ),( Jin Joo Park ),( Mi-seung Shin ),( Choong Hwan Kwak ),( Bong-ryeol Lee ),( Sung-ji Park ),( Hae-young Lee ),( Sang-hyun Kim ),( Seok-min Kang ),( Byung-su Yoo ),( Joong-wha Chung ),( S 대한내과학회 2021 The Korean Journal of Internal Medicine Vol.36 No.4
Background/Aims: To examine the prevalence and clinical characteristics of apparent treatment-resistant hypertension among ambulatory hypertensive patients. Methods: We enrolled adult ambulatory hypertensive patients at 13 well-qualified general hospitals in Korea from January to June 2012. Apparent resistant hypertension was defined as an elevated blood pressure > 140/90 mmHg with the use of three antihypertensive agents, including diuretics, or ≥ 4 antihypertensives, regardless of the blood pressure. Controlled hypertension was defined as a blood pressure within the target using three antihypertensives, including diuretics. Results: Among 16,915 hypertensive patients, 1,172 (6.9%) had controlled hypertension, and 1,514 (8.9%) had apparent treatment-resistant hypertension. Patients with apparent treatment-resistant hypertension had an earlier onset of hypertension (56.8 years vs. 58.8 years, p = 0.007) and higher body mass index (26.3 kg/㎡ vs. 24.9 kg/㎡, p < 0.001) than those with controlled hypertension. Drug compliance did not differ between groups. In the multivariable analysis, earlier onset of hypertension (odds ratio [OR], 0.98; 95% confidence interval [CI], 0.97 to 0.99; p < 0.001) and the presence of comorbidities (OR, 2.06; 95% CI, 1.27 to 3.35; p < 0.001), such as diabetes mellitus, ischemic heart disease, heart failure, and chronic kidney disease, were independent predictors. Among the patients with apparent treatment-resistant hypertension, only 5.2% were receiving ≥ 2 antihypertensives at maximally tolerated doses. Conclusions: Apparent treatment-resistant hypertension prevalence is 8.9% among ambulatory hypertensive patients in Korea. An earlier onset of hypertension and the presence of comorbidities are independent predictors. Optimization of medical treatment may reduce the rate of apparent treatment-resistant hypertension.
Functional Group-Selective Adsorption Using Scanning Tunneling Microscopy
Min, Young Hwan,Park, Eun Hee,Kim, Do Hwan,Kim, Sehun American Chemical Society 2012 ACS NANO Vol.6 No.4
<P>In this study, we selectively enhanced two types of adsorption of 3-mercaptoisobutyric acid on a Ge(100) surface by using the tunneling electrons from an STM and the catalytic effect of an STM tip. 3-Mercaptoisobutyric acid has two functional groups: a carboxylic acid group at one end of the molecule and a thiol group at the other end. It was found that the adsorption occurring through the carboxylic acid group was selectively enhanced by the application of electrons tunneling between an STM tip and the surface. Using this enhancement, it was possible to make thiol group-terminated surfaces at any desired location. In addition, <I>via</I> the use of a tungsten STM tip coated with a tungsten oxide (WO<SUB>3</SUB>) layer, we selectively catalyzed the adsorption through the thiol group. Using this catalysis, it was possible to generate carboxylic acid group-terminated surfaces at any desired location. This functional group-selective adsorption using STM could be applied in positive lithographic methods to produce semiconductor substrates terminated by desired functional groups.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2012/ancac3.2012.6.issue-4/nn300686y/production/images/medium/nn-2012-00686y_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn300686y'>ACS Electronic Supporting Info</A></P>
STM Tip Catalyzed Adsorption of Thiol Molecules at the Nanometer Scale
Min, Young Hwan,Jung, Soon Jung,Youn, Young -Sang,Kim, Do Hwan,Kim, Sehun American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.26
<P>The tungsten oxide covered tungsten (W) tip of a scanning tunneling microscope was found to act as a catalyst to catalyze the S−H dissociative adsorption of phenylthiol and 1-octanethiol molecules onto a Ge(100) surface. By varying the distance between the tip and the surface, the area of the tip-catalyzed adsorption could be controlled. We have found that the thiol headgroup is the critical functional group for this catalysis and the catalytic material is the tungsten oxide layer of the tip. This local tip-catalyzed adsorption may be used in positive lithographic methods to produce nanoscale patterning on semiconductor substrates.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-26/ja101166m/production/images/medium/ja-2010-01166m_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja101166m'>ACS Electronic Supporting Info</A></P>