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- 저자 : 황재원(J. W. Hwang) (검색결과 23 건)
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황재원(J.W.Hwang),김민호(M.H.Kirn),박재근(J.K.Park),Wu deyu,Liu Shenghua,채재우(J.O.Chae) 한국자동차공학회 1999 한국 자동차공학회논문집 Vol.7 No.9
In this paper, a zero-dimensional two zone model is developed to investigate the effects of variable valve timing on combustion process in SI engine. The simulation results show that the predicted data has good agreement with experimental ones. The useful information of combustion process such like residual gas fraction, cylinder pressure, cylinder temperature and NO concentration can be obtained and the effects of engine variables on combustion processes and performances can be evaluated.
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Thickness Optimization of Thin-film SCNT Cathode for Low-temperature Solid Oxide Fuel Cells
J. Hwang(황재원),S. Ryu(류상봉),S. W. Cha(차석원) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
Lowering the operating temperature of solid oxide fuel cells (SOFCs) offers many advantages such as improved system reliability and reduced material costs. However, slow oxygen reduction reaction (ORR) kinetics act as a bottleneck in the operation of SOFCs at lower temperatures. The use of mixed ionic and electronic conductors (MIEC) as a cathode can drastically enhance ORR kinetics by extending the reaction sites from the triple-phase boundary (TPB) to the entire surface of the cathode. Therefore, enhancement in performance can be expected as MIEC cathodes become thicker. But in practice, factors such as adhesion with the electrolyte, thermal agglomeration must be considered when determining the optimal thickness of the cathode. In this study, SrCo0.8Nb0.1Ta0.1O3-δ (SCNT), a recently developed MIEC material with high catalytic activity, was utilized as a cathode for our low-temperature solid oxide fuel cells (LT-SOFCs) using pulsed laser deposition (PLD). Electrochemical examination and microstructure characterization were carried out to investigate the effect of SCNT thickness on microstructure and SOFC performance.
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Multivone모델을 이용한 분사율 변화에 따른 직접분사식 디젤엔진의 배기가스 특성 예측에 관한 연구
황재원(J.W.Hwang),박재근(J.H.Park),갈한주(H.J.Kal),김만호(M.H.Kim),Liu Sheghua(Liu Shemghua),채재우(J.O.Chae) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
A multizone phenomenological combustion model, in which the burn rate is governed by the rate of fuel vaporization and mixing, is developed to study the effects of fuel injection rate shapes on exhaust emissions of direct injection diesel engines. The extended Zel'dovich mechanism is used to estimate the NO formation. This model is calibrated with the experimental data. Comparison between the results calculated by the model and experimental results shows that the model has a good predictive capability for cylinder pressure, heat release rate and exhaust emissions. And this study was investigated according to injection rate shapes. The results predicted by the model show that fuel amount of premixed combustion affects NO formation and NO is reduced by 14% with soot 7% increased at 1900rpm 50% load condition.<br/>
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스파크플러그를 이용한 실린더내의 실화강도 측정에 관한 연구
황재원(J.W.Hwang),박재근(J.K.Park),고용수(Y.S.Ko),조민석(M.S.Jo),A.A.Martychenko(A.A.Martychenko),채재우(J.O.Chae) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
Engine misfires (total or partial) cause a negative effect on exhaust emissions such like HC, CO and NOx. Moreover, it causes damage the three-way-catalyst(TWC) system permanently. So, it make shorten the life time of TWC. These are basic reasons why Environmental Protection Agency(EPA) and the California Air Resources Board (CARB) mandated the detection of engine misfires in their OBD-II (On-Board Diagnostics II) regulations. For the last several years, automobile manufacturers and their suppliers have been working on various solutions for the misfire detection challenge. Many have implemented a solution called Crankshaft Velocity Flluctuation(CVF). which utilizes the crank sensor input to calculate the variation of the crankshaft rotational speed. But this approach limited due to the fact that there could be problem during certain engine condition such like deceleration or high speed condition. This study introduced the new method of misfire detection using breakdown voltage(BDV) between electrodes. This misfire detection system also predict the engine pressure, temperature indirectly using paschen's law<br/>
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유닛인젝터용 고속응답 솔레노이드 설계 및 응용에 관한 연구
황재원(J. W. Hwang),양이진(I. J. Yang),정영식(Y. S. Jeong),이상만(S. M. Lee),채재우(J. O. Chae) 한국자동차공학회 1998 한국 자동차공학회논문집 Vol.6 No.1
Most of fuel-injection system operated with mechanical methods are difficult to control the in quantity and injection timing as well as injection rate exactly. Moreover high pressure injection scheme is never be realized with conventional one. On the other hand, serious air pollution can be lessened with injection system equipped with those functions. Therefore, electronically controlled Unit Injector(UI) appeared to satify above mentioned desires. However, it is still difficult that the most important part, especially solenoid valve, is analyzed precisely, because of the existence of complex combination of electro magnetics, electrics and dynamic problems.<br/> In this study, experimental and theoretical analysis are accomplished for understanding of solevalve characteristics and further its design. As the result, the follows are obtained 1) As the increase of wire diameter, the response time became shorter and optimal inductance existed in relwith the response time and wire diameter. 2) According to increasing input voltage, the tracforce increased, otherwise the response time was shortened. 3) As the increase of armature stroke, the traction force decreased and the response time became longer.<br/>
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솔레노이드 밸브를 이용한 직접분사식 디젤기관의 분사율 제어 및 배기 저감에 관한 연구
채재우(J.O.Chae),이상만(S.M.Lee),황재원(J.W.Hwang),양이진(I.J.Yang),장석채(S.C.Chang),갈한주(H.J.Kal),정영식(Y.S.Jeong),A.A.Martychenko(A.A.Martychenko),Balin Andrei(Balin Andrei) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_1
A very fast solenoid valve has been developed to modulate the pressure of fuel pressure in the injection system of a D.I. Diesel engine. The working process of solenoid has been analyzed and calculated for each characteristic period. The modulated pressure by solenoid valve varies needle lifting process and therefore cause different injection rate. An investigation into the application of electronically controlled solenoid valve to reduce emissions of NOx and soot has been carried out in both conventional and newly designed solenoid valve actuated injection system. Conventional and electronically controlled comparisons of emission products were made under 1500 rpm engine speed, 3/4 load conditions. The outlook for the use of electronically controlled fuel injection technology is described in the light of the results obtained.<br/>
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[가솔린엔진] 밸브개폐시기가변에 따른 엔진 특성의 예측에 관한 연구
황재원(J.W. Hwang),김만호(M.H. Kim),박재근(J.K. Park),Wu deyu,Liu Shenghua,채재우(J.O. Chae) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper, a zero-dimensional two zone model is developed to investigate the effects of variable valve timing on combustion process in SI engine. The simulation results show that the predicted data has good agreement with experimental ones. The useful information of combustion process such like residual gas fraction, cylinder pressure, cylinder temperature and NO concentration can be obtained and the effects of engine variables on combustion processes and performances can be evaluated
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