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RISS 인기검색어
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- 저자 : 안철봉(Chul-Bong An) (검색결과 7 건)
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판형열교환기의 수치해석을 위한 최소 검사체적과 난류모델에 대한 해석적 연구
봉재현(Jae Hyun Bong),안철봉(Chul Bong An),조홍현(Honghyun Cho) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.11
The purpose of this study is to determine the minimum control volume and select the optimum turbulent model of plate heat exchanger. The theoretical study on minimum control volume was performed with the duct number, and the that on optimum turbulent model was carried out with a variation of turbulent model. As a result, the minimum control volume was selected a least of 6 duct number for given duct angles. Besides, the Martin equation had a similar trend with the k-ε model. However, other models had some difference friction factors with Reynolds number and duct angle.
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안철봉,최병기 한국공작기계학회 1999 한국생산제조학회지 Vol.8 No.1
This distribution of fatigue crack growth rate is subjected to the measuring interval and calculated method of growth rate. In this paper, in order to establish the method of determining the distribution of fatigue crack growth rate, which ignores those influences, a series of fatigue crack growth experiments and measuring intervals of crack length calculated reasonable are presented. The main conclusions obtained as summarized as follows: 1) As a result of the ΔP constant test and ΔK constant test, it is thought that an approximate measuring interval of 0.3~0.7 ㎜ is reasonable, which allows for few errors and is little subjected to the calculated method of creak growth rate. 2) After generally comparing the error estimation by using the experimental data of CCT specimen with the error rating of the CT specimens, it is possible that the fatigue test has few errors within the measuring interval, ξ(Δa/W)=0.0067~0.014, regardless of the dimension o specimen geometry.
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엔진 연소실 내에서 노크와 화염 소화가 발생할 때의 열전달 모델링
홍명석,안철봉 조선대학교 생산기술연구소 1996 生産技術硏究 Vol.18 No.2
Heat transfer rates present in an engine cylinder undergoing knock are known to be larger than the rates associated with normal engine operation. Further, at the time of knock the largest heat fluxes are associated with locations on the cylinder wall where the flame is locally quenching. In this study, heat transfer processes at the flame wall interface during a knock event are analytically and computationally investigated. Computationally, the governing equations for a one dimensional flame quenching event are solved using a reduced chemical reaction mechanism. Analytically, scaling relations for the flame heat release rates are used in the governing equations to determine the heat transfer rates. It is found that while pressure transients modify the wall heat flux. the absolute value of the pressure is the most significant parameter in predicting the maximum heat flux. The magnitudes of the peak wall heat flux are accurately predicted with respect to the peak pressure for both the analytical and computational models. In the range of pressure examined, a linear relationship was found between the peak flux and pressure both for the computational and analytical models. The linear relationxhip between the pressure and the peak flux was found to be invalid when the flame quenching process was disrupted by the pressure fluctuations for pressure oscillations with characteristic time on the order of the quenching process.
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포트 분사 4밸브 엔진에서의 첫 번 크랭크 사이클 중 실린더 내부의 연료전달
홍명석,안철봉,박용태 조선대학교 동력자원연구소 1997 動力資源硏究所誌 Vol.19 No.1
Fuel transport was visualized within the cylinder of a port injected four-valve SI engine having a transparent cylinder liner. Measurements were made while motoring at 250rpm to simulate cranking conditions prior to the first firing cycle, and at 750rpm to examine the effects of engine speed. A production GM Quad-4 cylinder head was used, and the stock single-jet port fuel injector was used to inject indolene. A digital camera was used to capture back-lighted images of cylinder wall wetting for open and closed intake valve injection. In addition, two-dimensional planar imaging of Mie scattering from the indolene fuel droplets was used to characterize the fuel droplet distribution as a function of crank angle for open and closed intake valve injection. LDV was used to measure the droplet and air velocities near the intake valves during fuel injection. It was found that with open-valve injection a large fraction of the fuel impinged on the cylinder wall opposite the intake valves. This fuel did not completely vaporize over the engine cycle and built up over successive motored cycles. The small droplets that impinged upon the cylinder wall coalesced quickly due to surface tension forces, which impeded fuel vaporization from the cylinder wall. For closed-valve injection the fuel was stripped from the intake valves and ports very shortly after intake valve opening by the incoming air. There was very little impingement of fuel on the cylinder walls with closed-valve injection, but some fuel droplets apparently impinged on the piston top. It was observed that the droplets from closed-valve injection tend to be larger than those from open-valve injection, although this was not quantified. With closed-valve injection, droplets entering the cylinder had lower velocities than the incoming air. With open-valve injection, the early droplets entering the cylinder had higher velocities than the incoming air, but the droplets and air velocities were very close for most of the injection period.
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홍명석,안철봉 조선대학교 동력자원연구소 1996 動力資源硏究所誌 Vol.18 No.2
A simple but accurate model for the combustion efficiency of 4-stroke homogemeous charge spark ignition engines has been developed based upon thermochemical equilibrium arguments. This model assumes that the combustion efficiency is a function of only the fuel-air equivalence ratio for hydrocarbon fules with a hydrogen-to-carbon ratio similar to that of iso-octane. This model was shown to accurately predict experimental data for ranges of compression ratio, load, ignition timing, and speed typical of the normal engine design and operation. The model slightly overpredicts the data for high than typical engine speeds and is not applicable to engines operating near the partial burn, ignition, or lean misfire limits. An example of the potential usefulness of this model is also briefly discussed.
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