곡관에서의 천음속 및 초음속 사각 공동 유동에 대한 연구

김희동(Huey Dong Kim),예아란(A Ran Ye),Das 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.5-2

Comprehensive Analysis of Low-Molecular-Weight Human Plasma Proteome Using Top-Down Mass Spectrometry

Cheon, Dong Huey,Nam, Eun Ji,Park, Kyu Hyung,Woo, Se Joon,Lee, Hye Jin,Kim, Hee Cheol,Yang, Eun Gyeong,Lee, Cheolju,Lee, Ji Eun American Chemical Society 2016 JOURNAL OF PROTEOME RESEARCH Vol.15 No.1

<P>While human plasma serves as a great source for disease diagnosis, low-molecular-weight (LMVV) proteome (<30 kDa) has been shown to contain a rich source of diagnostic biomarkers. Here we employ top-down mass spectrometry to analyze the LMW proteoforms present in four types of human plasma samples pooled from three healthy controls (HCs) without immunoaffinity depletion and with depletion of the top two, six, and seven high-abundance proteins. The LMVV proteoforms were first fractionated based on molecular weight using gel-eluted liquid fraction entrapment electrophoresis (GELFrEE). Then, the GELFrEE fractions containing up to 30 kDa were subjected to nanocapillary-LC-MS/MS, and the high-resolution MS and MS/MS data were processed using ProSightPC 3.0. As a result, a total of 442 LMW proteins and cleaved products, including those with post-translational modifications and single amino acid variations, were identified. From additional comparative analysis of plasma samples without immunoaffinity depletion between HCs and colorectal cancer (CRC) patients via top-down approach, tens of LMW proteoforms, including platelet factor 4, were found to show >1.5-fold changes between the plasma samples of HCs and CRC patients, and six of the LMVV proteins were verified by Western blot analysis.</P>

Steady and Unsteady Rayleigh Flow with Heat Addition at High Subsonic Mach Numbers

Rajarshi Das,Huey Dong Kim 한국추진공학회 2013 한국추진공학회 학술대회논문집 Vol.2013 No.12

The heat addition process in compressible flows essentially accompanies unsteadiness, but such a time-dependent behavior of the compressible Rayleigh flow has seldom been known to date. In the present study, an analytical study has been performed to investigate the effect of different types of heat transfer to compressible flows at high subsonic Mach numbers. Changes in basic flow properties due to both steady and unsteady heat transfer into a constant area, frictionless duct over different periods of time were solved numerically. Flow Mach number and velocity were observed to increase rapidly as the flow approached sonic conditions. Change in flow enthalpy and temperature were however different showing an increase initially and then reducing in the vicinity of sonic conditions. Once sonic conditions were attained, the trend in change of flow properties changed substantially with decrease in Mach number under further heat transfer. Attainment of sonic state was observed to depend largely on the amount of heat transfer and the initial conditions.

자동차 시트 프레임의 경량화 설계에 관한 연구

김흥건(Hong Gun Kim),최금호(Gum Ho Choe),이병휘(Byeong Huey Lee),조영태(Young Tae Cho),이동주(Dong Joo Lee) 한국공작기계학회 1999 한국공작기계학회지 Vol.8 No.5

A seat frame structure in automotive vehicles made of polymer matrix composite to achieve weight reduction at low cost was developed. In order to design and manufacture the actual product, studies on material selection and structural analysis were performed. Structural analysis was performed with a finite element method. The analysis was done for several cases suggested in various safety regulations. Each result was utilized to modify the actual shape to obtain a lighter, safer and more stable design. The final design was used to produce a sample bottom plate of the seat structure with reinforced by X-shape frame. Substitution of the material resulted in a weight reduction effect with equivalent strength, fatigue and impact characteristics.

DSMC Study on Supersonic Mirco-Orifice Flow

Md Abdullah Al Mamun,Huey Dong Kim 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12

곡면상에 설치된 열린 공동을 지나는 천음속/초음속 유동에 관한 연구 (Ⅱ)

예아란(A Ran Ye),Rajarshi Das,김희동(Huey Dong Kim) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.6

공동유동에 관한 연구는 공동시스템에서 발생하는 소음/진동 문제로 인하여 많은 연구가 이루어졌으며, 현제 항공우주 산업의 급속한 발전과 더불어 다양한 공학적 장치에 적용되고 있다. 하지만, 실제 공학적 응용에서 많이 적용되는 곡면 벽상에 설치한 공동유동에 관한 연구에 대해서는 거의 수행되지 않았다. 본 연구에서는 곡면벽상에 설치한 공동유동의 특성을 조사하기 위해 수치계산을 수행하였으며, 곡면의 곡률 반경의 비(L/R) 및 입구 유동의 마하수를 변화시켜, 천음속/초음속 공동유동에서 발생하는 압력진동을 조사하였다. 그 결과 곡면에 부착된 공동유동의 경우 와류의 상호작용으로 인한 압력 교란을 완화시켰으나, 압력 진동의 진폭을 증가시켰으며, 또한 마하수가 증가함에 따라 압력 진동의 진폭이 증가하였다. 주파수 분석 결과, 곡관의 무차원 진동수는 직관에 비해 낮은 값이 측정되었으며, 또한 Rossiter의 실험값에 비해 낮은 값을 가졌다. Investigations into cavity flows have been conducted for noise and vibration problems that arise in cavity systems. Cavity systems have been applied in engineering devices and have undergone rapid development in the aerospace industry. Meanwhile, to the author"s best knowledge, the cavity on a curved wall has been seldom studied. The present work is conducted to study the flow physics of a cavity mounted on a curved wall. Numerical analysis is performed to investigate the cavity flow. Two variables of sub- and supersonic cavity flows were considered: the radius of curvature of the curved wall (L/R) and the inlet Mach number. The results show that the uniform vortex generated by the cavity flow on the curved wall stabilize the pressure fluctuation as time passes. As the inlet Mach number increases, the pressure fluctuation amplitude increases. The results obtained from the curved wall are compared with those from a straight wall using Rossiter"s formula. The Strouhal number of the curved wall is lower than that of the straight wall. Lower Strouhal numbers have been obtained in the present computational fluid dynamics (CFD) results than in the theoretical results using Rossiter"s formula.

곡면상에 설치된 열린 공동을 지나는 천음속/초음속 유동에 관한 연구 (I)

예아란(A Ran Ye),Rajarshi Das,김희동(Huey Dong Kim) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.3

공동유동은 종래 많은 연구가 수행되었으나 대부분의 연구는 공동 상류의 압력구배가 없는 수평면 상에 위치한 공동 유동에 대한 연구가 수행되어 왔으며, 실제 공학적 응용에서 나타나는 곡면 벽상에 위치한 공동 유동에 대한 연구는 거의 수행되지 않고 있다. 일반적으로 곡면 벽상에 위치한 공동유동에는 원심력이 작용하여 종래의 공동 유동 연구결과와 상이한 유동특성을 가질 것으로 판단되나, 이러한 데이터는 지금까지 보고되지 않았다. 본 연구에서는 곡면 벽상에 설치한 공동 유동을 수치해석법으로 조사하여 곡면의 곡률반경 및 유동의 마하수가 천음속 및 초음속 공동유동의 특성에 미치는 영향을 조사하였다. 그 결과 곡면의 곡률반경이 작아질수록, 유동의 마하수가 증가할수록, 공동내부에서 발생하는 피크압력의 크기는 증가하였으며 공동으로 인한 전압력손실 증가한다는 것을 확인할 수 있다. Investigations into cavity flows have been conducted for decades now, most of them being about zeropressure-gradient flows entering a cavity on a straight wall. However, the flow over curved walls in real-life situations has not been fully investigated. As cavity flows on curved walls exert centrifugal force, these walls are likely to possess different features from straight walls. To verify this possibility, this study investigated cavity flows on curved walls. Using numerical method, the effect of two variables, namely, radius of curvature on a curved wall and inlet Mach number, were investigated for subsonic and supersonic cavity flows. The result demonstrates that the value of the peak pressure generated inside the cavity increases with the decrease in the radius of curvature on a curved wall or an increase in the inlet Mach number. The total pressure loss in the cavity also results in an increase in the cavity drag.

Processing of syndecan-2 by matrix metalloproteinase-14 and effect of its cleavage on VEGF-induced tube formation of HUVECs

Lee, Young Hun,Park, Jun Hyoung,Cheon, Dong Huey,Kim, Taeyoung,Park, Yae Eun,Oh, Eok-Soo,Lee, Ji Eun,Lee, Seung-Taek Portland Press Ltd. 2017 Biochemical journal Vol. No.

<P>Syndecans (SDCs) are transmembrane proteoglycans that are involved in cell adhesion and cell communication. Specifically, SDC2 plays a key role in tumorigenesis, metastasis, and angiogenesis. Previously, we found that rat SDC2 is shed by matrix metalloproteinase-7 (MMP-7) in colon cancer cells. Here, we analyzed the susceptibility of rat SDC2 to various MMPs. We found that the rat SDC2 ectodomain (ECD) fused to the C-terminal Fc region, which was expressed in mammalian cells, was cleaved more efficiently by MMP-14 than MMP-7. Likewise, when anchored on the surface of HeLa cells, rat SDC2 was cleaved more efficiently by the treatment of MMP-14 than MMP-7 and was shed more readily by membrane-anchored MMP-14 than soluble MMP-14. Furthermore, MMP-14 cleaved recombinant SDC2-ECD expressed in <I>Escherichia coli</I> into multiple fragments. Using N-terminal amino acid sequencing and the top-down proteomics approach, we determined that the major cleavage sites were S<SUP>88</SUP>↓L<SUP>89</SUP>, T<SUP>98</SUP>↓M<SUP>99</SUP>, T<SUP>100</SUP>↓L<SUP>101</SUP>, D<SUP>132</SUP>↓P<SUP>133</SUP>, and N<SUP>148</SUP>↓L<SUP>149</SUP> for rat SDC2-ECD and S<SUP>55</SUP>↓G<SUP>56</SUP>, S<SUP>65</SUP>↓P<SUP>66</SUP>, P<SUP>75</SUP>↓K<SUP>76</SUP>, N<SUP>92</SUP>↓I<SUP>93</SUP> D<SUP>122</SUP>↓P<SUP>123</SUP>, and S<SUP>138</SUP>↓L<SUP>139</SUP> for human SDC2-ECD. Finally, the rat and human SDC2-ECD lost the ability to suppress vascular endothelial growth factor-induced formation of capillary-like tubes by human umbilical vein endothelial cells following cleavage by MMP-14, but its major cleavage-site mutant of rat SDC2-ECD did not. These results suggest that MMP-14 is a novel enzyme responsible for degrading SDC2 and impairing its physiological roles including angiogenesis.</P>

Drosophila hygrosensation requires the TRP channels water witch and nanchung

Liu, Lei,Li, Yuhong,Wang, Runping,Yin, Chong,Dong, Qian,Hing, Huey,Kim, Changsoo,Welsh, Michael J. Nature Publishing Group 2007 Nature Vol.450 No.7167

The ability to detect variations in humidity is critical for many animals. Birds, reptiles and insects all show preferences for specific humidities that influence their mating, reproduction and geographic distribution. Because of their large surface area to volume ratio, insects are particularly sensitive to humidity, and its detection can influence their survival. Two types of hygroreceptors exist in insects: one responds to an increase (moist receptor) and the other to a reduction (dry receptor) in humidity. Although previous data indicated that mechanosensation might contribute to hygrosensation, the cellular basis of hygrosensation and the genes involved in detecting humidity remain unknown. To understand better the molecular bases of humidity sensing, we investigated several genes encoding channels associated with mechanosensation, thermosensing or water transport. Here we identify two Drosophila melanogaster transient receptor potential channels needed for sensing humidity: CG31284, named by us water witch (wtrw), which is required to detect moist air, and nanchung (nan), which is involved in detecting dry air. Neurons associated with specialized sensory hairs in the third segment of the antenna express these channels, and neurons expressing wtrw and nan project to central nervous system regions associated with mechanosensation. Construction of the hygrosensing system with opposing receptors may allow an organism to very sensitively detect changes in environmental humidity.

An Experimental Study on the Supersonic, Dual, Coaxial, Swirling Jet

Kwon-Hee Lee(이권희),Toshiaki Setoguchi(토시아키 세토구치),Huey-Dong Kim(김희동) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.8