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고밀도 추기형 광디스크의 기록 파라미터 변화에 대한 열전달 해석
홍성국(S. K. Hong),이정두(J.D. Lee),조형희(H. H. Cho) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
The present study conducted heat transfer analysis in multi-layer of DVD-R. It is necessary to analyze heat transfer during the recording process to find the optimum laser power and write strategy in DVD-R. This study investigated effects of recording parameters such as laser power, recording speed, write strategy. In order to evaluate the thermal interference between previous mark and next mark, the effect of mark arrangement was studied. The optimum laser power was estimated, comparing an optimum mark length with the calculated mark lengths, The calculated results showed the need for the proper selection of write strategy for optimum recording. The results presented that next mark size was influenced by previous mark and land sizes.
강관구(K. Kang),홍성국(S.K. Hong),노동순(D.S. Noh),유홍선(H.S. Ryou) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.3
A pure oxygen combustion technology is crucial in Carbon Capture and Storage (CCS) technology especially in capturing of CO₂, where CCS will reduce 9 GtCO₂ by 2050, which is 19% of the total CO₂ reduction amount. To make pure oxygen combustion feasible, a regenerative system is required to enhance the efficiency of pure oxygen combustion system. However, an existing air combustion technology is not directly applicable due to the absence of nitrogen that occupies the 78% of air. This study, therefore, investigates the heat and fluid flow in a regenerative system for pure oxygen combustion by using commercial CFD software, FLUENT. Our regenerative system is composed of aluminium packed spheres. The effect of the amount of packed spheres in regenerator and the effect of presence or absence of a bypass of exhaust gas are investigated. The more thermal mass in regenerator makes the steady-state time longer and temperature variation between heating and regenerating cycle smaller. In the case of absence of bypass, the regenerator saturates because of enthalpy imbalance between exhaust gas and oxygen. We find that 40% of exhaust gas is to be bypassed to prevent the saturation of regenerator.
랜드/그루브 기록형 상변화 광디스크 박막에 대한 열전달 해석
이정두(J.D.Lee),홍성국(S.K.Hong),조형희(H.H.Cho) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
This study deals with the heat transfer analysis on phase change optical disc with land/groove recording by means of numerical method. Finite difference time domain(FDTD) method was used to obtain the amount of absorption of light propagating inside disc and finite difference element(FEM) method was used to calculate the temperature distribution. The calculated results present the detailed information of recording characteristics on the phase change optical disc. The temperature profiles are quite different between the land track and the groove track. The recorded mark shape on land track is smaller and more elliptic than that on groove track. It is shown that the thermal problem to the neighboring track takes place due to secondary peaks. It is found that the different write strategy should be applied to land and groove recording, respectively.