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Lee, Deokjung,Kozlowski, Tomasz,Downar, Thomas J. Elsevier 2015 Annals of nuclear energy Vol.77 No.-
<P><B>Abstract</B></P> <P>Previous researchers have shown that the simplified P<SUB>3</SUB> (SP<SUB>3</SUB>) approximation is capable of providing sufficiently high accuracy for both static and transient simulations for reactor core analysis with considerably less computational expense than higher order transport methods such as the discrete ordinate or the full spherical harmonics methods. The objective of this paper is to provide a consistent comparison of two-group (2G) and multi-group (MG) diffusion and SP<SUB>3</SUB> transport for rod ejection accident (REA) in a practical light water reactor (LWR) problem. The analysis is performed on two numerical benchmarks, a 3×3 assembly mini-core and a full pressurized water reactor (PWR) core. The calculations were performed using pin homogenized and assembly homogenized cross sections for a series of benchmarks of increasing difficulty, in two-dimensional (2D) and three-dimensional (3D), 2G and MG, diffusion and transport, as well as with and without feedback. All results show consistency with the reference results obtained from higher-order methods. It is demonstrated that the analyzed problems show small group-homogenization effects, but relatively significant transport effects which are satisfactorily addressed by the SP<SUB>3</SUB> transport method. The sensitivity tests also show that, for the REA simulation, the MG is more conservative than 2G, P<SUB>1</SUB> is more conservative than SP<SUB>3</SUB> for a 1/3 MOX loaded full-core problem.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The multi-group SP<SUB>3</SUB> method developed and implemented in PARCS for the MOX analysis. </LI> <LI> The verifications were performed in 2D and 3D, 2G and MG, diffusion and transport, with and without feedback. </LI> <LI> All results show consistency with the reference results obtained from the ANL P<SUB>N</SUB> transport code VARIANT for steady-state and transport calculations. </LI> <LI> It was found that the SP<SUB>3</SUB> angular approximation captures sufficient transport effects for both steady-state and transient, and provides essentially the same results as the VARIANT P<SUB>5</SUB> method. </LI> <LI> From the transient results of the full-core problem, it was noted that MG is more conservative than 2G, and P<SUB>1</SUB> is more conservative than SP<SUB>3</SUB>. </LI> </UL> </P>
김덕중(Deokjung Kim),이기수(Geesoo Lee),김현철(Hyunchul Kim),허형석(Hyungseok Heo),최승배(Seungbae Choi),이동채(Dongche Lee),조용석(Yongseok Cho) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
North America’s emission control regulation, which emphasizes on Partial Zero-emission Vehicle (PZEV), greatly reinforced its requirements and conditions on the evaporative emission through the air intake system when an engine was stopped. Accordingly, it can not meet PZEV on the absorption of evaporative emission by simply using a canister, as we had done previously. In this paper, eight types of HC traps, of which their shapes and manufacturing processes differed, were developed to reduce evaporative gas. We have conducted various kinds of tests to achieve absorption and desorption flux, which are needed for the Butane Working Capacity(BWC) test. In addition, the absorption performance of samples of the eight types of HC traps were examined by conducting the BWC test. The absorption and desorption performance of the HC traps were compared and analyzed. The results of the BWC test showed that the B0 type with (describe the filter type) had the highest loading weight of 16.2 g. The absorption loading weight of the HC trap after driving 20,000 ㎞ decreased by 4.9 g compared to that of the fresh sample.
흡기계 HC 흡착필터가 차량 증발가스 저감에 미치는 영향
김덕중(Deokjung Kim),이기수(Geesoo Lee),김현철(Hyunchul Kim),최승배(Seungbae Choi),이동채(Dongche Lee),임종순(Jongsoon Lim),조용석(Yongseok Cho) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The methods of reducing the amount of HC evaporative gas in the engine can be divided into two types: one involving the use of a catalyst, and another involving the use of an HC absorption filter. The method that involves the use of an HC absorption filter is recommendable as it would allow the evaporative gas in the intake manifold to be reduced when the engine is stopped. It is difficult, however, to predict the exact volume or the life span of absorption and desorption. Moreover, as the filter is to be installed in the air intake systems, air intake loss can occur. As such, a precise HC absorption filter design must be made, and repeated absorption and desorption tests, as well as a test of applicability to an actual vehicle, must be conducted. In this study, HC absorption filter was developed for use in reducing the evaporative gas in the air intake systems, and the Butane Working Capacity(BWC) test was conducted. The honeycomb type HC absorption filter, which shows the best absorption performance, was then installed in vehicle. 1-day diurnal test and hot soak test was then performed three times: before and after the installation of the HC absorption filter, and after sealing the air intake system. The results of the test show that the total HC evaporative gas emission after the installation of the HC absorption filter was 0.637 g/test, which represented a reduction of about 0.29 g compared to the gas emission (0.093 g/test) before the installation of the HC absorption filter. The efficiency of the HC absorption filter, which was calculated based on the result of its installation assessment, was shown to be 97.3%, which is a significantly high percentage.
5속 A/T용 댐퍼 클러치의 슬립 제어에 따른 주행 및 연비 특성
김덕중(Deokjung Kim),이기수(Geesoo Lee),김현철(Hyunchul Kim),허형석(Hyungseok Heo),이호길(Hogil Lee),장재덕(Jaeduk Jang),조용석(Yongseok Cho) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In recent years, the technologies for reduction of fuel consumption have became increasingly important due to protecting the global environment in an automotive industry. In line with this trend, energy loss in the transmission was mostly associated with the damper clutch slip in a torque converter. The aims of this paper were to introduce and evaluate of the characteristics of slip-controlled damper clutch system developed for the 5-speed transmission of 2,400 cc gasoline engine. The control design of technique was based on the PID controller with respect to engine road. At proving ground, driving characteristics of vehicle according to slip control parameters were evaluated. To attain slip-controlled damper clutch system, fuel economy mode test such as FTP-75 mode, Highway mode and NEDC mode for vehicle were conducted. As a results, fuel consumption of vehicle with slip-controlled damper clutch system effectively decreased by 5.5%, compared to the base system at FTP-75 mode.
PZEV 규제 대응 흡기계 증발가스 흡착 필터의 Mini SHED 평가
김덕중(Deokjung Kim),이기수(Geesoo Lee),김현철(Hyunchul Kim),허형석(Hyungseok Heo),최승배(Seungbae Choi),이동채(dongche Lee),조용석(Yongseok Cho) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
North America's representative emission control regulation, Partial Zero-Emission Vehicle (PZEV), greatly reinforced its requirements on the evaporative gas through the intake manifold when an engine was stopped. Since only using a canister could not meet enhanced regulations on the evaporative gas, new technologies for reducing the evaporative gas were required to satisfy the regulations regarding the control of the intake system's evaporative gas. In this study, three kinds of HC traps for 3L gasoline engine were developed to reduce the evaporative gas emission of the intake system. And Mini SHED performance tests for HC trap with honeycomb type were evaluated according to the test procedure specified by California Air Resources Board (CARB). Variations of evaporative emission gas were observed and analyzed on 1-Day diurnal test and 3-Day diurnal test including hot soak test. The result shows that the amount of generated evaporative gas emission was 43 ㎎/test satisfy the PZEV evaporative emission standard, 54㎎/test.
Lemaire, Matthieu,Lee, Hyunsuk,Tak, Nam-il,Lee, Hyun Chul,Lee, Deokjung Atomic Energy Society of Japan 2017 Journal of nuclear science and technology Vol.54 No.6
<P>This paper presents the application results of MCS/GAMMA+ to multi-physics analysis of OECD/NEA modular high temperature gas-cooled reactor (MHTGR) benchmark Phase I Exercise 3. It is a part of international R&D efforts lead by the Next Generation Nuclear Plant (NGNP) US project to improve the neutron-physics and thermal-fluid simulation of (high temperature gas-cooled reactors) HTGRs, one of the next generations of safer nuclear reactors. Accurate and validated analysis tools are indeed a crucial requirement for safety analysis and licensing of nuclear reactors. To guide this effort, a numerical benchmark on the MHTGR was created by the NGNP project and formally approved in 2012 for international participation by the OECD/NEA. The benchmark defines a common set of exercises and the comparison of solutions obtained with different analysis tools is expected to improve the understanding of simulation methods for HTGRs. The coupled neutronics/thermal-fluid solution presented in this paper was obtained with the neutron transport Monte Carlo code MCS developed by Ulsan National Institute of Science and Technology and the thermal-fluid code GAMMA+ developed by Korean Atomic Energy Research Institute. The purpose of this paper is to present the GAMMA+/MCS coupled system, the calculation methodology, and the obtained solutions.</P>
김덕중(Deokjung Kim),이기수(Geesoo Lee),김현철(Hyunchul Kim),오세두(Sedoo Oh),정수진(Soojin Jeong),표영덕(Youngdug Pyo) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
When DME fuel is used for the existing common rail diesel injector, the needle opening speed slows down because DME has a higher compressibility effect than diesel, and the speed at the nozzle hole outlet decreases due to a high pressure drop in the nozzle sheet. Most DME injectors are used with increased nozzle holes in the existing common rail injector for correction of calorific power. However, the required flow cannot be attained only by increasing nozzle holes, the lift design of needle sheet which determines the minimum passage area must be considered as well. This study focused on the design, processing and evaluation of nozzle for the development of an injector for DME. In particular, since the number and diameter of spray holes in the nozzle determine the supply volume of DME fuel to the combustion chamber in the cylinder, the changing spray flow by the changed number and diameter of nozzle holes was examined using existing VCO-type 6-hole nozzle with increased diameter and a SAC-type 5-hole nozzle with increased diameter. The applicability of a DME fuel spray injector was verified through comparison of spray flow with existing nozzle. The evaluation result showed that spray flow increased at 500 bar or lower operating pressure of DME.