Fuzzy H-continuous Mappings and Fuzzy Strongly Closed Graphs

Hur, K.,Ahn, Y.S.,Ryou, J.H. Korean Institute of Intelligent Systems 2002 한국지능시스템학회논문지 Vol.12 No.6

We introduce the concepts of fuzzy H-continuity and fuzzy strongly closed graph, respectively and investigate some of their properties.

냉축열 잠열재의 상변화 온도조절과 잠열특성

송현갑(H. K Song),유영선(Y. S. Ryou),노정근(J. G. Ro) 한국태양에너지학회 1998 한국태양에너지학회 학술대회논문집 Vol.- No.-

온축열재로 물성을 안정시켜 개발한 Na₂SO₄ㆍ10H₂O와 H₂O의 상변화 용도를 냉축열온도로 하향조절하여, 냉축열재로 활용할 수 있도록 잠열재의 상변화 온도조절기법을 실험적으로 확인하고, 온도조절과 상변화 사이클이 냉축열 특성에 미치는 영향을 실험적으로 분석하였다. In order to utilize Na₂SO₄ㆍ10H₂O and H₂O as clod thermal storage media, the theory of Phase Change Temperature Control (PCTC) and the crystallization model of PCM were suggested, and the phase change temperature of the PCM could be controlled bellow 0℃ with the PCTC theory.<br/> And the effect of PCTC and the phase change cycle on .the cold thermal storage characteristics of PCM was experimentally analysed.

농산물 저온저장을 위한 H2O-NaCl 혼합물의 축열 특성

송현갑(H.K.Song),유영선(Y.s.Ryou),박종길(J.G.Ro),노정근(J.K.Park) 한국태양에너지학회 1997 한국태양에너지학회 논문집 Vol.17 No.3

본 연구에서는 잠열온도 조절에 관한 이론과 상변화 잠열재의 결정핵형성이론 그리고 PCM 결정화 모델을 정립하고, 농산물 저온 저장에 이용할 수 있는 냉축열 잠열재로 H₂O를 선정하여 NaCl을 온도 조절제로 잠열온도를 조절하였으며, 상변화 사이클에 의한 열특성 변화 추이와 물성의 안정성을 실험적으로 분석하였다. The theory on phase change tel11JHClture control and nucleation of PCM was suggested in this research. The crystallization model of PCM was established. And H2O- NaCl mixtures were selected as cold storage materia1s for agricultural products and therrm-physica1 properies of the PCM were ana1yzed with eXJHirrenta1 processes including freeze-thaw cycles.<br/>

실내화재에서 연기거동에 미치는 복사영향에 대한 수치해석적 연구

정진용,유홍선,홍기배 한국화재소방학회 2000 한국화재소방학회논문지 Vol.14 No.3

본 연구는 두 가지 유형의 3차원 실내 공간내에서 화재 발생시 연기거동에 미치는 복사영향을 알아보기 위해 자체개발한 SMEP(Smoke Movement Estimating Program) field 모델을 사용하여 수치해석 하였다. PISO 알고리즘과 부력항을 포함한 수정 k - ε 난류모델을 사용한 SMEP은 연속, 운동, 에너지, 농도 그리고 복사 열 전달 방정식을 풀었으며, 복사 열 전달 방정식의 해석을 위하여 S-N 구분종좌표법을 채택하여 사용하였다. 수치해석 결과 연기의 온도분포는 복사를 고려하지 않고 대류만을 고려했을 경우 실험치와 많은 오차를 보였으나 복사를 함께 고려했을 경우는 실험치와 작은 오차범위로 비슷한 경향을 나타내었다. 이것은 연기속에 포함되어 있는 연소생성물 중 H2O와 CO2가스의 복사 영향 때문이며, 따라서 좀더 실제적인 화재해석에 있어서 복사는 반드시 고려되어야만 한다. This paper describes the smoke movement of a fire field model based on a self-developed SMEP(Smoke Movement Estimating Program) code to the simulation of fire induced flows in the two types of compartment space containing the radiation effect under smoke movement in room fire. The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k - ε turbulence model with buoyancy term. Also it solves the radiation equation using the discrete ordinates method. The result of the calculated smoke temperature containing radiation effect has shown reasonable agreement compared with the experimental data. On the other hand, a difference of a lot was found between the temperature predicted by the SMEP with only convection effect and obtained by the experimental result. This seems to come from the radiation effect of H2O and CO2 gas under smoke productions. Thus, the consideration of the radiation effect under smoke in fire may be necessary in order to produce more realistic result.

충돌분무의 액적 거동에 미치는 비등방성 난류특성의 영향에 대한 수치해석 연구

고권현(G. H. Ko),유홍선(H. S. Ryou) 한국전산유체공학회 2003 한국전산유체공학회지 Vol.8 No.4

It is an aim of this study to perform extensive numerical study for analyzing the anisotropic turbulence effects on spatial and temporal behaviors of droplet for impinging sprays. The turbulence model of Durbin is used for comparisons with the k-E model. The turbulence-induced dispersions of droplets are consider to describe the anisotropy of turbulence effectively and spray/wall interactions are simulated using the model of Lee and Ryou. Present study investigates the overall and the internal structures of impinging diesel sprays such as spray shapes, radius and height of wall sprays, Sauter mean diameter (SMD), local droplet velocity, and local gas velocity and compared the results with experimental data by two adopted turbulence models. When the anisotropy effect of turbulence is included, better predictions for both gas and droplet tangential velocities are obtained, compared to the k-ε model. It is concluded that anisotropic effect of turbulence should be considered for simulating impinging diesel sprays.

아트리움에서 화재 발생시 복사가 고려된 연기거동에 대한 수치해석 연구

정진용,유홍선,홍기배 한국화재소방학회 2001 한국화재소방학회논문지 Vol.15 No.1

본 연구는 3차원 아트리움 공간(일본의 SIVANS 아트리움) 내에서 화재 발생시 복사가 고려된 연기의 거동을 알아보기 위해 자체개발한 SMEP(Smile Movement Estimating Program) field 모델을 사용하여 수치해석하였다. PISO 알고리즘과 부력항을 포함한 수정 k-ε 난류모델을 사용한 SMEP은 연속, 운동, 에너지, 농도 그리고 복사 열 전달 방정식을 풀었으며, 복사 열 전달 방정식의 해석을 위하여 S-N 구분종좌표법을 채택하여 사용하였다. 수치해석 결과 연기의 온도분포는 복사와 대류를 함께 고려했을 경우가 대류만을 고려했을 경우 보다 실험결과와 근사한 경향을 나타내었다. 이것은 연기속에 포함되어 있는 연소 생성물 중 H₂O와 CO₂가스의 복사 영향 때문이며, 따라서 좀더 실제적인 화재해석에 있어서 연기의 복사 영향을 고려하는 것이 필요하다. 또한 연층의 하강 속도는 약 0.1m/s이였으며 피난수준인 바탁 1.5m까지 연층이 도달하는데에는 560kW의 Ultra Fast Fire의 경우 약 450초의 시간이 걸렸다. This paper describes the smoke filling process of a fire field model based on a self-developed SMEP (Smoke Movement Estimating Program) code to the simulation of fire induced flows in the atrium solves (SIVANS atrium at Japan) containing smike radiation effect. The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k-ε turbulence model with buoyancy term. Also it solves the radiation equation using the discrete ordinates method. The result of the calculated smoke temperature containing radiation effect has shown a better prediction than the result calculated by only convection effect in comparison with the experimental data. This seems to come from the radiation erect of H₂O and CO₂gas under smoke productions. Thus, the consideration of the radiation effect under smoke in fire should be necessary in order to get more realistic result. Also the numerical resuls indicated that the the smoke layer is developing at a tare of about 0.1 m/s. It would take about 450 seconds after starting the ultra fast of 560kW that the smoke layer move down to 1.5m above the escape level.

Fuzzy H-continuous Mappings and Fuzzy Strongly Closed Graphs

K.Hur,Y.S.Ahn,J.H. Ryou 한국지능시스템학회 2002 한국지능시스템학회논문지 Vol.12 No.6

그린하우스 열환경 조절을 위한 파라핀계 화합물(CnH2n+2)의 잠열 축열 특성

송현갑,유영선 한국농업기계학회 1996 바이오시스템공학 Vol.21 No.1

정적 연소실내의 분무특성에 관한 수치해석적 연구

양희천,유홍선,최영기 중앙대학교 기술과학연구소 1992 기술과학연구소 논문집 Vol.22 No.-

Since the combustion in direct injection engines was strongly influenced by the characteristics of the fuel spray, an understanding of the phenomena of fuel spray was essential to design of the direct injection engines. In this study the numerical simulations of the spray characteristics in a quiescent gaseous environment were performed using the spray model that could predict the interactions between spray droplets and gas fields. The governing equations were discretised by the finite volume method and the k-ε turbulence model which included the compressibility effects due to the compression/expansion of piston was used. The results showed tha the spray tip penetration and tip velocity were in good agreement with the experimental results qualitatively, except in the early stages of fuel spray. The discrepancy in the early stages of fuel spray was presumably due to the uncertainty of boundary conditions at the nozzle exit which included droplets size distributions, injection velocity and mass flow rate, etc.

운전상태에서의 유동장 및 분무특성에 미치는 분사압력의 영향에 대한 수치해석적 연구

최영기,유홍선,홍기배,양희천 중앙대학교 생산공학연구소 1992 생산공학연구소 논문집 Vol.1 No.1

Since the combustion in direct injection engines was strongly influenced by the characteristics of flow and spray, an understanding of the characteristics of those was essential to design of the direct injection engines. In this study the numerical analysis of the effects of injection pressure on the flow fields and the characteristics of spray in a motoring condition was performed using the spray model that could predict the interactions between spray droplets and gas fields. The governing equations were discretised by the finite volume method and the modified k- turbulence model which included the compressibility effects due to the compression/expansion of piston was used. The results showed that the radially strong inward squish flow or outward reverse-squish flow at the bowl lip was apparent due to the effect of the piston bowl. It was found that as the injection pressure increased, the evaporation rate of droplets was decreased due to the narrow width of spray and the increased number of droplets impinged on the bottom of piston bowl.