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박윤서(Park, Yun-Seo),최두석(Choi, Doo-Seuk),이주형(Lee, Ju-Hyung),신평우(Shin, Pyung-Woo),박성영(Park, Sung-Young) 한국산학기술학회 2012 한국산학기술학회논문지 Vol.13 No.3
본 연구에서는 유동해석과 실험을 통하여 소형엔진 흡기포트의 성능 최적화를 수행하였다. 포트각, 플랜지면 적 및 포트형상은 흡기포트의 성능을 결정하는 중요한 설계인자이다. 특히 가공곡률이 공기유량계수에 매우 중요한 영향을 미치는 핵심인자임을 확인하였다. 포트각과 플랜지면적이 증가하면, 흡기포트내의 압력분포와 압력기울기가 개선되어 공기유량계수가 개선되었다. 유동해석 결과는 플로우박스 실험결과 대비 최대 8% 오차를 보였으나, 설계 변수에 따른 공기유량계수 경향을 우수하게 반영하였다. 최적의 설계변수를 적용한 흡기포트 모델은 양산모델 대비 약 4.5% 개선된 공기유량계수 성능을 나타내었다. Performance optimization of a small engine intake port has been studied through computational and experimental approach. Port angle, flange area and port shape are very important design parameters affecting performance of an intake port. Especially, radius of curvature of intake port inner surface has major effect on the flow coefficient of an intake port. As increasing port angle and flange area, flow coefficient is increased because pressure distribution and pressure gradient in the intake port are improved. Even though computational results over-predict maximum 8% compared with experimental result, they describe the tendency of flow coefficient according to the design parameters. Optimized intake port shows about 4.5% improved flow performance.
저탄소강의 질화침탄과 산화처리시 분위기 변화에 따른 조직 및 부식특성에 관한 연구
신평우 ( Sin Pyeong U ),이구현 ( Lee Gu Hyeon ),남기석 ( Nam Gi Seog ),박율민 ( Park Yul Min ),조형준 ( Jo Hyeong Jun ) 한국열처리공학회 2004 熱處理工學會誌 Vol.17 No.2
N/A Nitrocarburizing was carried out with various CH, gas composition with 4 torr gas pressure at 570 C for 3 hours and post oxidation was carried out with 100% 0, gas atmosphere with 4 torr at different temperatures for various time. In the case of plasma nitrocarburizin, It is that the ratio of ε-Fe_(2·3)(N, C) and γ`-Fe,(C, N), which comprise the compound layer phase, depend on concentrations of N₂ gas and CH, such that when the concentration of N, and CH, increased, the ratio of γ`-Fe₄(C, N) decreased, but the ratio of ε-Fe_(2·3)(N, C) increased. The thickness of compound layer consistently increased as gas concentration increased regardless of N₂ and CH, expect when the concentration of CH, was 3.5 volume%, it decreased insignificantly. When oxidizing for 15min in the temperature range of 460-570℃, the study found small amount of Fe3O4 at the temperature of 460℃ and also found that amounts of Fe₂O₃ and Fe₃O₄ on the surface and amount of γ`-Fe₄(C, N) in the compound layer increased as the increased over 460℃, but the thickness of the compound layer decreased, Corrosion resistance was influenced by oxidation times and temperature.
플라즈마 침질탄화처리시 처리시간이 화합물층의 특성에 미치는 영향
박율민(Y. M. Park),신평우(P. W. Shin),조효석(H. S. Cho),남기석(K. S Nam),이구현(K. H. Lee) 한국진공학회(ASCT) 2000 Applied Science and Convergence Technology Vol.9 No.4
플라즈마 침질탄화처리는 보통탄소강, 저합금강 등에 내마모성, 내식성 및 내피로성 향상에 사용되어 있으며 자동차 부품, 기계류 부품, 공업용 공구 등에 적용할 수 있는 표면경화열처리이지만 내마모성 및 내식성을 향상시키는 단상의 ε 화합물층을 생성시키기는 어려운 문제점으로 남아 있다. 따라서 본 연구에서는 탄소강과 저합금강에 대해 질소와 CH₄ 가스농도를 변화시켜 플라즈마 침질탄화처리를 실시하여 단상의 ε 화합물층 생성가능성과 시간을 변화시켜 화합물층의 생성과정을 고찰하였다. ε 화합물층은 질소농도가 증가할수록 형성이 용이하였고 CH₄ 가스농도가 증가할수록 ε 화합물층의 형성이 용이하였지만 시멘타이트상이 생성되었다. 화합물층은 10분이 경과한 후 생성되었고 γ’상으로부터 시작되었으며 처리시간이 10시간 이상이 되면 화합물층내에 시멘타이트상이 생성되어 화합물층의 두께가 감소하였다. Plasma nitrocarburising is a thermochemical heat treatment, and can be used for plain carbon steels and low alloy steels to improve wear, corrosion and fatigue resistance. The process is performed on automotive parts, machinery parts and engineering tools. However, it is still facing problems in obtaining a mono ε phased compound layer. Therefore, the aim of this research is to investigate the possibility of forming a mono ε phased compound layer using a gas mixture of nitrogen and methane. ε was found that high nitrogen contents were essential for the production of ε phase compound layer and with increasing methane content in the gas mixture, ε phase compound layer was favoured. In addition, when the methane content was further increased, cementite was observed in the compound layer. γ' phase was produced after 10 minutes treatment time and cementite was formed in the compound layer resulting in decreasing the thickness of the compound layer.
이동균(Dong kyun Lee),박상우(Sang woo Park),신평우(Pyung woo Shin),이건엽(Gunyub Lee),문형석(Hyung Suk Mun) 한국철도학회 2018 한국철도학회 학술발표대회논문집 Vol.2018 No.5
철도차량은 육상을 이용하여 짧은 시간에 많은 화물을 수송할 수 있는 에너지 효율이 우수한 친환경적인 녹색수송 수단으로 전 세계의 수요가 급증하고 있으며 남북철도 연결과 함께 유라시아로 연결하는 대륙철도로의 진출을 추진하고 있다. 하지만, 남북 인접지역의 화물열차에는 서로 다른 제동장치를 사용하고 있어 인접지역의 제동장치 특성을 분석하고 혼합편성 상호운영을 위한 국내 제동장치의 방향을 소개하고자 한다. Railway vehicles are eco-friendly green transportation vehicles with excellent energy efficiency that can transport large quantities of cargo in a short time with using land, and it is increasing rapidly as the demand for in the world. It is promoting the entry of the continental railway linking to Eurasia with connecting to the South & North Korea Railway. However, since different brake control unit is used for the freight train in the South-North region, the characteristics of the brake control unit in the South-North region is analyzed and the directions of the domestic brake control unit for mixing and interoperability are introduced.
이구현(K . H . Lee),남기석(K . S . Nam),이상로(S . R . Lee),조효석(H . S . Cho),신평우(P . W . Shin),박율민(Y . M . Park) 한국열처리공학회 2001 熱處理工學會誌 Vol.14 No.2
N/A Plasma nitrocarburising and post oxidation were performed on SM45C steel using a plasma nitriding unit. Nitrocarburising was carried out with various methane gas compositions with 4 torr gas pressure at 570℃ for 3hours and post oxidation was carried out with 100% oxygen gas atmosphere with 4 torr at different temperatures for various times. It was found that the compound layer produced by plasma nitrocarburising consisted of predominantly ε-Fe_(2-3)(N,C) and a small proportion of γ-Fe₄(N,C). With increasing methane content in the gas mixture, a phase compound layer was favoured. In addition, when the methane content was further increased, cementite was observed in the compound layer. The very thin oxide layer on top of the compound layer was obtained by post oxidation. The formation of oxide phase was initially started from the magnetite(Fe₃O₄) and with increasing oxidation time, the oxide phase was increased. With increasing oxidation temperature, oxide phase was increased. However the oxide layer was split from the compound layer at high temperature. Corrosion resistance was slightly influenced by oxidation times and temperatures.