반구면경을 이용한 스펙트럼 방사율 측정법

배신철,오기수,Bae, Sin-Chul,Oh, Ki-Soo 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.6

It is studied that the measuring method of the spectral emissivity by using hemispherical mirror with an inclined observation hole. The in-service calibration method of mirror reflectivity is also dealed with. It is possible to apply this method on measuring emissivity of conductor or non-conductor.

NPE법을 이용한 절연재료의 유효열확산계수의 과도측정에 관한 연구

임동주,배신철,Lim, Dong Joo,Bae, Sin Chul 대한설비공학회 1990 설비공학 논문집 Vol.2 No.3

The objective of this study is to present an efficient measurement method of the effective thermal diffusivity for the fibrous insulation material. The non-linear parameter estimation (NPE) method is adapted for this analysis because of its accuracy and its results are compared with those by other direct methods such as CTP, CHP and STD method. A experimental system is constructed with bell-jar vaccum chamber, diffusion pump, tube type furnace, control unit and data acquisition system included with A/D converter and IBM XT/AT personal computer. The typical results obtained from this study are as follows; 1) NPE method can be recommended as an useful and accurate method to measure the effective thermal diffusivity of insuation material because it is shown that the measurement error compared with those by other direct methods is reduced for standard material, NBS-1450b. 2) NPE method can minimize the effects of ill-measured temperature due to external disturbance, because the final value is found by point to point estimating. 3) NPE method dose not depend on the kinds of heat flux, since the surfac temperature are used to estimate the thermal diffusivity. 4) With NPE method, compared with the steady state method, a measuring time and a sample size could be reduced.

승용차의 부분부하제어를 위한 스크류형 과급기 개발

배재일,배신철,Bea, Jae-Il,Bae, Sin-Chul 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.10

Turbo- or Super-charging has been used to boost engine power for Gasoline- and Diesel Engine since beginning of 20th century. So far turbo-charger has enjoyed a high reputation in the charging field for its technical advantages such as no demand of operation power from engine and an excellent charging effect in a static operation at mid- and high engine speed. A mechanically driven super-charger, however, is now popular due to the high engine power at quick change of the driving mode - high engine torque even at low engine speed. Since super-charger needs operation power from engine, it is difficult to improve its relatively higher fuel consumption than that of turbo-charger. This negative point is still an obstacle to the wide use of supercharger. Super-charger using screw-type compressor will fulfill the purpose to reduce fuel consumption by minimizing operation power owing to no charge at idling or part load driving condition. This study aims to develop power control concept to achieve the minimization of operation power. A screw type super-charger was modified in design partially and installed with an internal bypass valve and a bypass tube to control charging pressure at part load. The various control concepts show a possibility to reduce operation power of super-charger.

라플라스 변환을 이용한 1차원 열전도의 수치해석

신운철 ( Woon Chul Shin ),배신철 ( Sin Chul Bae ) 한국안전학회 2007 한국안전학회지 Vol.22 No.4

당근의 동결건조에서 승화건조시간 예측연구

박노현(Noh-Hyun Park),김병삼(Byung-Sam Kim),배신철(Sin-Chul Bae) 한국식품과학회 1993 한국식품과학회지 Vol.25 No.4

차폐층을 갖는 튜브형전기로의 복사 열전달 연구

裵信徹,柳秀烈 단국대학교 1994 論文集 Vol.28 No.-

One way of reducing radiant heat transfer between surfaces is to use the shields which are made from highly reflective or lowly emissivitive materials. In this study, the surface temperature of tube type furnace and the radiation shields were measured in the vacuum bell-jar. The tube type furnace was made by stainless steel 304 foil with 0.03 mm and 0.05 mm. The experimental data were compared with theoretical results. Since the heat convection effects can be neglected due to experiment in vaccum chamber, and the heat conduction effects can be also neglected due to very thin the thickness of specimen, there are only the radiative heat transfer. To find the effect of shield numbers, the electric furnaces with the one to five shields were made. As the results, the energy consumption decrease as increasing the number of shields, and using lower emissivitive material. To determine the position placing the specimen for measuring the thermophysical properties, the surface temperature distribution in axial direction was measured and compared with theoretical results. Since the errors among the experimental and theoretical data were changed in the range of ±5%, the accuracy of the present method was verified. Although the maximum temperature of the furnace rise as increasing shield number, since the difficulties and tedious job in manufacturing the furnace with more numbers of shield beyond the arailability of the reducing the energy consumptions, the use of two or three shields can be recommended. Also it was found that the specimen should be placed in 52.2% midsection in axial length of the furnace, and the maximum temperature difference between the end and midsection of the furnace was 20 degree under the present condition.

정온법을 이용한 절연재료의 열확산 계수측정

裵信徹,金泰甲 단국대학교 1989 論文集 Vol.23 No.-

Serveral transient techniques were used for measuring the thermal diffusivities of fibrous insulating meterials. The transient technique use din the present study was the constant temperature plate method. The mathematical model of the CTP method is based on a semi-infinite slab with finite thickness, with the front of the slab modeled at constant temperature and the rear face as being maintained at the initial temperature. At time zero, the sample was placed for several minutes on a hot plate maintained at constant temperature. The temperatures of both sample on a hot plate maintained at constant temperature. The temperature of both sample faces were measured as a function of time to confirm the boundary conditions. Temperature of an interior position of the sample were measured and were used to calculate the termal diffusivity. The boundary conditions were satisfied during the time from zero to the time just before the rear face temperature started to rise. The thermal diffusivities of NBS, blanket, made in U.S.A. and several insulators made in Korea were measured about 300℃ to confirm the accuracy of the experimental apparatus.

二軸 對稱形 不規則 斷面 圖形에 대한 等角寫像 函數의 유도와 非熱源 熱傳導 解析에의 應用

裵信徹,李俊昊 단국대학교 1987 論文集 Vol.21 No.-

Generally it is very difficult to solve the equation of heat conduction analytically on regions with irregular configuration. So, these kinds of problems can be solved by numerical methods using computer. The representative numerical methods on heat conduction problem are F.D.M. and F.E.M. But these methods contain several important considerations such as C.P.U time and the number of segments and so on. If we know the mapping functions transforming irregular shapes into unit circle, we can overcome these difficult factors. In this paper, the mapping functions on three kinds of irregular shapes were derived and the Dirichlet problems of two dimensional heat conduction without heat source were solved by using them. Actually these conditions are very interesting in fields of unclear and heat treatment in industry. The derived mapping solutions are very simple forms containing fundamental functions such as Bessel and exponential functions. Specifically, at centers of shapes the value of zero order Bessel function of the 1st kind is 1 so that mapping solutions become only exponential functions. To verify the accuracy of this method, mapping solution on square shape was compared with exact and F.D.M solutions. The result showed that this was a good method to solve several non-analytic problems.

遷移區域을 考廬한 對流熱傳達에 관한 硏究

裵信徹 단국대학교 1982 論文集 Vol.16 No.-

A comparative study on the heat transfer in the aerodynamic heating for cases of two-region model and three-region model is presented; the two region model consists of the laminar and turbulent regions, while the three region model includes the laminar, transition and turbulent regions. For unit Reynolds numbers of 8×10 exp (6) and 4×10 exp (7) the onset transition Reynolds numbers are 1.94×10 exp (6) and 5.36×10 exp (6), respectively. It may be said that the onset transition Reynolds number increases as the unit Reynolds number increases. Mach number influences more on the end transition Reynolds number than on the onset transition Reynolds number. Transition for Μ=4.5 occurs earlier than for Μ=2.5 by 21%. A relationship for the end transition Reynolds number of flat plate and cone may be expressed by the following formula and the formula may be used to correlate the existing experimental data within ±12%. 〔(Rete)_δ〕_c/〔(Rete)_δ〕_p=3.4-0.3Μ_δ Heat transfer for the case of two-region model is larger than that for three-region model. The difference of heat transfer between the two models decreases as the Mach number increases.

동결 건조기의 최적 운전 기법

裵信徹,李近熙 단국대학교 1993 論文集 Vol.27 No.-

The problem of operating a freeze dryer to obtain a fixed final moisture content in minimum time is formulated as an optimal control problem. The energy radated from the heat plate, and total pressure in drying chamber are considered as control variables. Constraints are placed on the system state variables by the scorch point of the dried product and the melting point of the frozen interface. The optimum control policy at the beginning of the run, when neither of the two temperature constraints is active, has been establishen through a theoritical analysis under pseudo-steady state assumptions. For certain cases the nature of the overall optimum control policy has been found. The numerical solution of the steady and nonsteady state problem indicates that if a control policy is optimum for the steady state problem, then this control policy is also optimum for the nonsteady state problem.