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철도터널 화재 시 구난역 내의 연기거동에 대한 수치해석 연구
홍사훈(Hong Sa Hoon),유홍선(Ryou Hong Sun),이성혁(Lee Seong Hyuk) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
The present study performed numerical investigation to analyze the smoke behavior in the rescue station by using the commercial CFD code (FLUENT Ver 6.3). The present study adopted a 10MW ultrafast mode for simulation, and it also used the MVHS(Modify Volumetric Heat Source) model modified from the original VHS(Volumetric Heat Source) model in order to treat the product generation and the oxygen consumption under the stoichiometric state. In addition, the present simulation includes the species conservation equation for the materialization of heat source and the estimation of smoke movement. From the results, the smoke flows are moving along the ceiling because of thermal buoyancy force and as time goes, the smoke gradually moves downward at the vicinity of the entrance. Moreover, without using ventilation, it is found that the smoke flows no longer spread across the cross-passages because the pressure in the non-accident tunnel is higher than that in the accident tunnel.
미세 딤플 가공 표면의 수력학적 윤활특성에 대한 수치해석
홍사훈(Sa Hoon Hong),이재응(Jaeung Lee),조민행(Min Haeng Cho),이성혁(Seong Hyuk Lee) 한국전산유체공학회 2009 한국전산유체공학회지 Vol.14 No.4
This study deals with the numerical investigation on two-dimensional lubrication characteristics of micro-dimple shapes fabricated on solid surfaces by using the commercial CFD code (Fluent V.6.3) to examine the influence of micro dimple depth and width on the reduction in friction under the sliding plate condition. In addition, single and multiple dimple arrays are simulated, all for a fixed area fraction of dimple on the surface. As a result, it is found that the existence of micro-dimpled surface makes it possible to substantially reduce the friction forces exerted on the surfaces, and such an optimum dimple depth would be present because the dimple depth larger than the optimum value did no longer affect the reduction in shear stresses, indicating that the reduction of friction is likely to be associated with inner flows of lubricant inside dimples. Moreover, it is observed that at the fixed area fraction, the friction reduction increases with the increase of dimple diameter.
가교화 후 하이드록시프로필화한 복합변성 쌀전분의 이화학적 특성
최현욱 ( Hyun Wook Choi ),홍사훈 ( Sa Hoon Hong ),최성원 ( Sung Won Choi ),김창남 ( Chang Nam Kim ),유승석 ( Seung Seok Yoo ),김병용 ( Byung Yong Kim ),백무열 ( Moo Yeol Baik ) 한국산업식품공학회 2011 산업 식품공학 Vol.15 No.4
Physicochemical properties of dual-modified rice starches, cross-linked (with POCl3) and hydroxypropylated (with propylene oxide) rice starches, were studied. Rice starch was cross-linked using POCl3 (0.005%, 0.02% (v/w)) at 45oC for 2 hr and then hydroxypropylated using propylene oxide (2%, 6%, 12% (v/w)) at 45oC for 24 hr, respectively. Swelling power, solubility, thermal properties (DSC) and pasting properties (RVA) of cross-linked and hydroxypropylated (CLHP) rice starches were determined. Swelling power of CLHP rice starch increased at relatively lower temperature than native rice starch. Solubility of CLHP rice starch was lower than that of native rice starch. Peak viscosity of CLHP rice starch was lower than that of native starch while holding strength and final viscosity were increased with modification. Breakdown value was lower and setback value was higher than native rice starch. DSC thermal transitions of CLHP rice starch shifted toward lower temperature. Amylopectin-melting enthalpy of CLHP rice starch decreased, whereas it was not affected by the amount of POCl3.
박병옥(Byung-ok Park),이세영(Se-young Lee),박윤택(Yun-taek Park),이재균(Jae-gyun Lee),남호성(Ho-seong Nam),홍사훈(Sa-hoon Hong) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
엔진 개발시 블로바이 가스 내에 함유되어 엔진 외부로 빠져나가는 블로아웃 오일의 양을 최소화하기 위해, 다양한 구조나 복잡하고 값비싼 기구들을 채택하여 적용하고 있다. 특히 배기가스 규제가 강화됨에 따라, 배기가스에 악영향을 미치는 블로아웃 오일 양을 감소해야 하는 필요성은 더욱 증가하고 있다. 본 논문은 독창적이면서도 단순한 구조를 통해 블로바이 가스 내에 함유된 엔진오일의 분리 성능을 높여서 블로아웃 오일 양을 절감하고, 엔진 외부에 형성된 블로바이 가스용 파이프 및 호스류를 대폭 삭제함으로써 엔진 원가 절감 및 외관 향상과 함께 차량 탑재성 개선 등을 동시에 달성한 내용에 관한 것이다.