포화상태에 놓인 C-Type 액체수소 탱크의 슬로싱이 열 유속과 BOG에 미치는 변화의 수치적 분석

이진호,황세윤,이성제,이장현,Lee, Jin-Ho,Hwang, Se-Yun,Lee, Sung-Je,Lee, Jang Hyun 한국전산구조공학회 2022 한국전산구조공학회논문집 Vol.35 No.5

본 논문은 슬로싱 상태에 놓인 포화 상태 액체수소탱크에서 열 유속 및 BOG(Boil-off gas)의 경향을 다루고 있다. 특히, 액체-기체간의 침투 및 혼합에 의한 열 교환에 관심을 두었다. 먼저, VOF(Volume of fluid)와 Eulerian 기반의 다상 유동모델로 모형 슬로싱 실험을 모사하여 압력을 예측하고 계측된 값과 비교하였다. 자유 수면 및 충격 압력 실험 결과와 해석 결과를 비교하였으며, 유체의 속도 예측에서 정확할 수 있음을 간접적으로 증명하였다. 그리고 2차원의 Type-C 원통형 수소탱크를 대상으로 다상열유동해석을 수행하였다. 이때 포화상태에 놓인 액체 및 기체수소를 가정하고, 해석을 통해 각 상간의 혼합에 의한 열 교환의 수준을 확인하고자 하였다. 단, 상간의 열 교환만을 관심으로 두고 있었으므로 질량전달 및 기화모델은 해석에서 제외하였다. 최종적으로 상의 혼합으로 인해 액체수소로 유입되는 열 유속의 기여도에 대하여 정리하였다. 또한 액체수소로 유입되는 열 유속과 집중 질량 기반의 간이식을 통해 BOG 발생량 및 경향을 예측하고 분석하였다. This study was conducted to predict the tendency for heat exchange and boil-off gas (BOG) in a liquefied hydrogen tank under sloshing excitation. First, athe fluid domain excited by sloshing was modeled using a multiphase-thermal flow domain in which liquid hydrogen and hydrogen gas are in the saturated state. Both the the volume of fluid (VOF) and Eulerian-based multi-phase flow methods were applied to validate the accuracy of the pressure prediction. Second, it was indirectly shown that the fluid velocity prediction could be accurate by comparing the free surface and impact pressure from the computational fluid dynamics with those from the experimental results. Thereafter, the heat ingress from the external convective heat flux was reflected on the outer surfaces of the hydrogen tank. Eulerian-based multiphase-heat flow analysis was performed for a two-dimensional Type-C cylindrical hydrogen tank under rotational sloshing motion, and an inflation technique was applied to transform the fluid domain into a computational grid model. The heat exchange and heat flux in the hydrogen liquid-gas mixture were calculated throughout the analysis,, whereas the mass transfer and vaporization models were excluded to account for the pure heat exchange between the liquid and gas in the saturated state. In addition, forced convective heat transfer by sloshing on the inner wall of the tank was not reflected so that the heat exchange in the multiphase flow of liquid and gas could only be considered. Finally, the effect of sloshing on the amount of heat exchange between liquid and gas hydrogen was discussed. Considering the heat ingress into liquid hydrogen according to the presence/absence of a sloshing excitation, the amount of heat flux and BOG were discussed for each filling ratio.

권두언-설비의 당면과제 해결 위해 관련단체가 공동노력 해야

이진호,Lee, Jin-Ho 대한기계설비건설협회 2004 기계설비 Vol.167 No.-

전자선 직접묘사에 의한 Deep Submicron NMOSFET 제작 및 특성

이진호,김천수,이형섭,전영진,김대용,Lee, Jin-Ho,Kim, Cheon-Soo,Lee, Heyung-Sub,Jeon, Young-Jin,Kim, Dae-Yong 한국전자통신연구원 1992 전자통신 Vol.14 No.1

전자선 직접묘사 (E-beam direct writing lithography) 방법을 이용하여 $0.2\mum$ 과 $0.3\mum$ 의 게이트길이를 가지는 NMOS 트랜지스터를 제작하였다. 게이트만 전자선 직접묘사 방법으로 정의하고 나머지는 optical stepper를 이용하는 Mix & Match 방식을 사용하였다. 게이트산화막의 두께는 최소 6nm까지 성장시켰으며, 트랜지스터구조로서는 lightly-doped drain(LDD) 구조를 채택하였다. 짧은 채널효과 및 punch through를 줄이기 위한 방안으로 채널에 깊이 붕소이온을 주입하는 방법과 well을 고농도로 도핑하는 방법 및 소스와 드레인에 $p^-$halo를 이온주입하는 enhanced lightly-doped drain(ELDD) 방법을 적용하였으며, 제작후 성능을 각각 비교하였다. 제작된 $0.2\mum$의 게이트길이를 가지는 소자에서는 문턱전압과 subthreshold기울기는 각각 0.69V 및 88mV/dec. 이었으며, Vds=3.3V에서 측정한 포화 transconductance와 포화 드레인전류는 각각 200mS/mm, 0.6mA/$\mum$이었다. $0.3\mum$소자에서는 문턱전압과 subthreshold 기울기는 각각 0.72V 및 82mV/dec. 이었으며, Vds=3.3V에서 측정한 포화 transconductance는 184mS/mm이었다. 이러한 결과는 전원전압이 3.3V일 때 실제 ULSI에 적용가능함을 알 수 있다.

개질형 On-Site 수소충전소의 리스크 감소를 위해 요구되는 SIL 등급 달성 방안에 관한 연구

이진호,임재용,Lee, Jin Ho,Lim, Jae-Yong 한국안전학회 2020 한국안전학회지 Vol.35 No.6

In recent years, hydrogen has received much attention as an alternative energy source to fossil fuels. In order to ensure safety from the increasing number of hydrogen refueling stations, prevention methods have been required. In this regard, this study suggested an approach to reduce the risk of hydrogen refueling station by increasing Safety Integrity Level (SIL) for a Steam Methane Reformer (SMR) in On-Site Hydrogen Refueling Station. The worst scenario in the SMR was selected by HAZOP and the required SIL for the worst scenario was identified by LOPA. To verify the required SIL, the PFDavg.(1/RRF) of Safety Instrumented System (SIS) in SMR was calculated by using realistic failure rate data of SIS. Next, several conditions were tested by varying the sensor redundancy and proof test interval reduction and their effects on risk reduction factor were investigated. Consequently, an improved condition, which were the redundancy of two-out-of-three and the proof test interval of twelve months, achieved the tolerable risk resulting in the magnitude of risk reduction factor ten times greater than that of the baseline condition.

상호 변조 및 불요 신호에 대한 탐색레이더 부 체계의 EMI 시험 기법

이진호,Lee, Jin-Ho 한국군사과학기술학회 2007 한국군사과학기술학회지 Vol.10 No.2

MIL-STD-461E, EMI military standard for the equipment and subsystems, requires reception characteristic tests to verify the susceptibility of a receiver against the jntermodulation and spurious signals. Because the CS103 and CS104 of MIL-STD-461E show the test configuration of the equipment unit like a traditional receiver, it is possible to verify the susceptibility only for the reception signal through analog filters. However, at present when software programming techniques make a progress, the CS103 and CS104 tests need to evaluate the reception signal of the subsystem which includes both the digital filtering effects and analog filter characteristics. These test and evaluation techniques applied to a surveillance radar subsystem. This paper researched the EMI test methods in order to confirm feasibility of these test and evaluation techniques. Also the test results are compared and analyzed.

Protein Adsorption and Desorption Behavior on the Surfaces with Differently Chargeable Functional Groups

이진호,김형우(Heoung Woo Kim),박병기(Pyong Ki Pak),김승수(Sung Soo Kim),이해방(Hai Bang Lee) 한국고분자학회 1993 한국고분자학회 학술대회 연구논문 초록집 Vol.1993 No.10

수학과 개정교육과정과 대학수학능력시험 체제 개편에 관한 고찰

이진호,Lee, Jin-Ho 한국수학사학회 2009 Journal for history of mathematics Vol.22 No.1

본 연구에서는 2012학년도 대학수학능력시험의 출제체제 개편에 맞추어 현재 시행되고 있는 대학수학능력시험에서 나타나는 문제점과 그 개선 방안에 대하여 연구하였다. 대학수학능력시험은 1994년도 시행이후 제5차, 6차, 7차 교육과정을 거치면서 교육과정이 바뀜에 따라 몇 차례 개정을 하여 현행에 이르고 있다. 2007년 2월 발표된 수학과 교육과정 개정에 의해 2009년부터 개정된 교육과정에 따라 교육이 이루어지고 2012학년도의 대학수학능력시험은 그 출제 및 응시체제가 개편되어야 한다. 지난 교육과정과 2009학년도부터 시행하게 되는 개정교육과정에 따른 대학수학능력시험 출제체제의 변천과정을 조사하고 외국의 대학입시시험의 출제 범위를 우리의 교육과정과 비교하여 현행 대학수학능력시험에서 나타나는 문제점을 개선할 수 있는 방안을 제언한다. In this paper we check over some problems in College Scholastic Ability Test(CSAT) Mathematics section and propose some methods to improve the CSAT Mathematics section. CSAT has been changed several times with the change of the school curriculum. A Mathematics amended curriculum will apply in 2009 and we have to reorganize the system of CSAT. We investigate the changes in school curriculum and system of CSAT. Also we make a comparative study of the range of possible questions of CSAT with those of SAT and foreign national entrance exam for college.

동일평면상에 존재하는 복수표면균열의 피로성장수명예측

이진호,최용식,김영진,Lee, J.H.,Choy, Y.S.,Kim, Y.J. 대한기계학회 1993 대한기계학회논문집 Vol.17 No.7

The objective of this paper is to develop a computational model for predicting the fatigue propagation of collinear multiple surface cracks under constant amplitude and variable amplitude loadings. After examining fatigue crack growth behavior for CT specimens and single surface crack specimens, empirical equations of(11) and(12) are proposed for the prediction of fatigue life in a multiple surface crack geometry. The accuracy of the proposed model is verified using a life prediction computer program. Several case studies were performed to check the accuracy of the proposed model and to verify the usefulness of the developed program. Good agreement is observed between the numerical results based on the proposed model and the published experimental data.

DSMC(Direct Simulation Monte Carlo)방법을 이용한 마이크로관 내에서의 2 상유동에 관한 연구

이진호,유동훈,이태홍,Lee, Jin-Ho,Ryu, Dong-Hun,Lee, Tae-Hong 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.12

In contrast to the high demand for MEMS devices, microflow analysis is not feasible even for single-phase flow with conventional Navier-Stokes equation because of non-continuum effect when characteristic dimension is comparable with local mean free path. DSMC is one of particle based DNS(Direct Numerical Simulation) methods that uses no continuum assumption. In this paper, gas flow in microchannel is studied using DSMC. Interfacial shear and flow characteristics are observed and compared with the results of gas flow that is in contact with liquid case and solid wall case. The simulation is limited to the case of equilibrium steady state and evaporation/condensation coefficient is assumed to be the same and unity. System temperature remains constant and the interfacial shear appears to be small compared to the result with solid wall. This is because particles evaporated and reflected from the liquid surface form high density layer near the interface with liquid flow.

휜 형상에 따른 증발기의 전열 성능

이진호,권오갑,Lee, Jin Ho,Kwon, O Kap 대한설비공학회 1990 설비공학 논문집 Vol.2 No.1

An experimental investigation was made to study the performance characteristics of evaporator having different fin configurations and tube inner grooves. Three different types of fin such as super slitted fin, slitted fin, plain fin, and two types of tube such as inner grooved tube, and bare tube, are tested varying the air velocity, evaporation temperature and superheat of refrigerant. Results show that in the range of air side Reynolds number $3{\times}10^3\;-\;1.5{\times}10^4$ evaporator with super slitted fin and inner grooved tube shows best performance. It is 80% higher in overall heat transfer coefficient and 2.6 times higher in pressure loss compared to that with plain fin inner grooved tube. Friction factor is found to be almost independent of evaporating temperature and degree of superheat, while Colburn j factor varies with evaporating temperature.