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적응 격자계를 이용한 초음속 난류유동장의 측면제트분사에 대한 수치적연구
김종록(Jong-Rok Kim),김익태(Ik-Tae Kim),김재수(Jae-Soo Kim) 한국전산유체공학회 2001 한국전산유체공학회 학술대회논문집 Vol.2001 No.-
Two-dimensional steady flowfields generated by slot injection into supersonic flow are numerically simulated by the integration of Navier-stokes equation with two-equation k-ε turbulence model. High-order upwind scheme is used on unstructured adaptive meshes. The numerical results are compared with experimental data in terms of surface static pressure distributions. the length of the upstream separation region, and the height of the Mach surface for steady flowfields with a Mach number of 3.71 and a unit Reynolds number of 5.83×10^6/m.
적응 격자계를 이용한 초음속 난류유동장의 측면제트분사에 대한 수치적연구
김종록(J.R. Kim),김익태(I.T. Kim),김재수(J.S. Kim) 한국전산유체공학회 2001 한국전산유체공학회지 Vol.6 No.2
Two-dimensional steady flowfields generated by slot injection into supersonic flow are numerically simulated by the integration of Navier-stokes equation with two-equation k-turbulence model. High-order upwind scheme is used on unstructured adaptive meshes. The numerical results are compared with experimental data in terms of surface static pressure distributions, the length of the upstream separation region, and the height of the Mach surface for steady flowfields with a Mach number of 3.71 and a unit Reynolds number of 5.83×10^6/m.
X-ray 현미경을 이용한 GDL(가스확산층)에서 물의 거동 및 분포에 관한 실험적 연구
김종록(Jongrok Kim),김태주(TaeJoo Kim),김무환(MooHwan Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
The water management is one of the most critical issues for the PEMFC commercialization. In order to make a proper scheme for water management, the information of behavior of water is very important. So, the X-ray imaging has joined the canon of diagnostic methods for the fuel cell research and is applied worldwide with qualitative and quantitative results. In this study, we did experimental study about behavior of water in GDL using X-ray microscope in Pohang Accelerator Laboratory. For this aim, we prepared a simple experimental model which has two channels on both face of GDL. The behavior of water in the GDL were observed as functions of the thickness of compressed GDL and the pressure of injected water on a channel. X-ray microscope shows the water in GDL had different behavior for each thickness of GDL and each pressure of injected water on steady and unsteady conditions. The water easily permeated to GDL when compressed GDL was thick and pressure of injected water was high.
김종록(Kim Jong-rok) 한국어문학회 2011 語文學 Vol.0 No.111
The purposes of this study are to analyze actual conditions of sentences used in scientific research papers, and to search for viable solutions. Through analytical research, it is confirmed that scientific papers contain great deal of grammar errors such as unsuitable words, unnecessary omitting, errors of sentences component co-occurrence, and wrong parallelism. In addition, the majority of writers of scientific papers are not using proper sentences connectives and postposition particles. Also, in case of grammatical sentence rules, spacing and orthography are especially mis-used. Therefore, the author could ascertained that writers of scientific research papers are short of grammatical knowledge and clauses of grammatical sentence rules. Moreover, the author found the writers lack in their ability to make precise and effective sentences with their idea. To cope with these problems, proper grammar and writing courses should be conducted in the level of middle school and high school education. Furthermore, universities are required to open various composition classes and establish writing center for continual tutelage. Lastly, Scientific Research society should change their minds of Korean sentence writing, and should include clauses of proper sentences grammar into evaluation of papers. Also, it is necessary for scientific Research society to host essay-writing workshops, or to organize the writing deliberation advisory committee.
김종록(Jong Rok Kim) 한국추진공학회 2013 한국추진공학회지 Vol.17 No.4
A study is analyzed on the adverse pressure gradient and the transient regime of supersonic diffuser with Computational Fluid Dynamic. The flow field of supersonic diffuser is calculated using Axisymmetric two-dimensional Navier-Stokes equation with k-? turbulence model. The transient simulation is compared in terms of mach number and static temperature of vacuum chamber according to pressure variation of rocket engine combustion chamber. Combustion gas flow into the vacuum chamber during operation of the supersonic diffuser. According to this phenomenon, the pressure and the temperature rise in the vacuum chamber were observed. Thus, the protection system will be necessary to prevent the pressure and temperature rise in the transition process during operation of the subsonic diffuser.
연료전지 다공성막을 통한 수분증발량의 정량적 측정에 관한 실험적 연구
김종록(Jongrok Kim),김무환(Moo Hwan Kim),손상영(Sang Young Son) 대한기계학회 2012 大韓機械學會論文集B Vol.36 No.6
연료전지 시스템에서 잔류 수분의 제거과정은 연료전지의 성능 및 수명 관리를 위해 중요한 과정이다. 효과적인 수분 제거과정의 설계를 위해서는 연료전지내의 수분 제거 특성에 대한 이해가 필수적이다. 이를 위해 본 연구에서는 연료전지의 다공성막인 가스확산층을 통한 수분증발량을 정상상태에서 측정하는 실험 기법을 개발하였다. 이 기법을 이용하여 연료전지의 잔류수분 제거 현상을 모사하는 실험장치를 개발하였다. 그리고 건조가스와 가스확산층의 변수가 수분에 미치는 영향을 실험적으로 측정하였다. 건조가스의 습도가 낮고, 유량이 높을수록 가스확산층을 통해 증발되는 수분량이 높았다. 또한 가스확산층의 두께가 얇을수록 수분 증발량이 높은 특성을 확인하였다. Removing residual water in a fuel cell is a critical operational process for managing its performance and controlling its lifetime. Understanding the mechanism of water transport in fuel cells is essential for the design of the water removal process. In this study, an experimental method for measuring the water evaporation rate through a gas diffusion layer, which is a porous medium, under steady-state conditions was developed. Experimental bench tests were conducted to apply the developed method. Then, the effects of various parameters of the drying gas and the gas diffusion layer were experimentally measured. The water evaporation rate increased as the humidity of the drying gas decreased and the flow rate of the drying gas increased. In addition, a thinner gas diffusion layer yielded a higher water evaporation rate.