• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.329-330
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• 2009

Food waste contains almost no heavy metals and high fuel ratio 0.14-0.17 that makes it a good candidate for solid fuel. Thermogravimetric analysis showed that volatile matter volatilizes at $200-400^{\circ}C$, and ignition temperature is $460^{\circ}C$. Combustion efficiency measured from energy balance before and after combustion was over 99%. Pulverized fuel made from food waste is a new and renewable energy which contribute to low carbon green economic growth.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.195-206
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• 2003

Polymer electrolyte membrane fuel cells(PEMFC) are very interesting power source due to high power density, simple construction and operation at low temperature. But they have problems such as high cost, improvement of performance and effect of temperature. This problems can be approached using mathematical models which are useful tools for analysis and optimization of fuel cell performance and for heat and water management, in this paper, transient model consists of various energy terms associated with fuel cell operation using the mass and energy balance equation. And water transfer in the membrane is composed of back diffusion and electro-osmotic drag. The temperature calculated by transient model approximately agreed with the temperature measured by experiment in constant current condition.

• 설비공학논문집
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• 제26권2호
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• pp.79-85
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• 2014

In general, building energy performance is evaluated with a detailed transient building energy simulation program. However, energy evaluation tools with the bin method are still used, because of their simple and easy way to calculate building energy performance, without reducing their precision. In this research, several heating and cooling degree day methods are compared, and evaluated with their performance for variable base temperature. This analysis considered about ten years of the continuous outdoor temperature, in the Seoul and Busan areas. It is concluded that the simplified bin method is more or less acceptable for Seoul and Busan, compared with the detailed hourly bin method.

• 한국태양에너지학회 논문집
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• 제24권3호
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• pp.39-46
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• 2004

In this paper, thermodynamic design data for heating of double-effect absorption system using LiCl-water for evaporator heating source of sofar energy are investigated for the water-LiCl pair and a comparative study of the water-LiCl pair with the water-LiBr pair is given used for the computer simulation. The computer simulation is based on mass, material and heat balance equations for each part of the system. Coefficients of performance and flow ratios for effects of different operating temperatures are investigated. It is found that the heating COP is higher for the water -LiCl pair than for the water-LiBr pair, and FR is lower for the water-LiCl pair than for the water LiBr pair.

• 융복합기술연구소 논문집
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• 제3권2호
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• pp.57-60
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• 2013

The purpose of this study is to analysis of how to calculate fuel efficiency in major development countries (U.S. and Europe) and energy consumption formular derivation of domestic CNG fuel and prove by vehicle test. The formula of fuel consumption is different in mpg(mile per gallon), l/100km, and km/l each countries. CNG fuel has a significant impact on fuel density, composition, and Hydro-Carbon ratio. So, this study how to measurement and calculation procedures of CNG gaseous fueled vehicle energy consumption rate.

• Coupled systems mechanics
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• 제11권6호
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• pp.543-556
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• 2022

Delamination of multilayered inhomogeneous beam that exhibits non-linear relaxation behavior is analyzed in the present paper. The layers are inhomogeneous in the thickness direction. The dealamination crack is located symmetrically with respect to the mid-span. The relaxation is treated by applying a non-linear stress-straintime constitutive relation. The material properties which are involved in the constitutive relation are distributed continuously along the thickness direction of the layer. The delamination is analyzed by applying the J-integral approach. A time-dependent solution to the J-integral that accounts for the non-linear relaxation behavior is derived. The delamination is studied also in terms of the time-dependent strain energy release rate. The balance of the energy is analyzed in order to obtain a non-linear time-dependent solution to the strain energy release rate. The fact that the strain energy release rate is identical with the J-integral value proves the correctness of the non-linear solutions derived in the present paper. The variation of the J-integral value with time due to the non-linear relaxation behavior is evaluated by applying the solution derived.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.201-204
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• 2008

FRP 합성재료로 구속된 콘크리트의 응력-변형률 응답을 합리적으로 예측할 수 있는 해석모델이 제시되었다. 제안된 모델은 하중이 증가함에 따라 점진적으로 발생하는 미세균열에 의한 부피팽창이 미세재료구조의 손상을 나타내는 중요한 척도이며, 이에 손상정도에 따라 하중지지능력을 일관되게 산정할 수 있다는 기본개념에 근거한다. 이를 위하여 제안모델은 면적변형률 및 공극의 함수로 표시된 탄성계수, 팽창콘크리트와 구속매체의 상호작용을 나타내는 에너지 평형식, 변화하는 구속력 및 점증계산논리를 포함한다. 따라서 실험으로부터 유도된 팽창비 관계식으로부터 횡방향 혹은 부피팽창변형률을 산정하는 기존의 해석모델과는 달리 역학적 거동 및 에너지 평형식으로부터 연속적으로 변화하는 횡방향 변형률을 산정한다.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.137-146
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• 2007

This study is about the passive cooling effects of three outdoor solar shading facilities as trees, pergola with wistaria vine and membrane shading structure, which are expected to provide cool spots in the summer. Field observations of measuring thermal environment of selected facilities is executed. Thermal environment measuring was categorized as short wave radiation, long wave radiation, net radiation, globe temperature, surface temperature measured by infrared camera. Heat transfer mechanism is analyzed with overall data from field measurement. Results from this study are as below; 1) Radiation balance measured on shaded surface under membrane shading structure was 17%($86W/m^2$) of the unshaded surface radiation balance($511W/m^2$). 2) Surface temperature comparison between vegetation and membrane of the shading structure is performed at 3 o'clock in the afternoon. Surface temperature of vegetation was same as air temperature and that of membrane was $5^{\circ}C$ higher than air temperature. Vegetation transpiration is considered as the causing factor which make those differences. 3) Results from this study could be used as fundamental data for reducing heat island phenomena and continuos research on this subject would be needed.

• 한국태양에너지학회 논문집
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• 제21권1호
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• pp.33-42
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• 2001

The paper discusses the modelling of the thermal storage roof with the air circulation system. In this system, the fully glazed absorber plate is put on the top of the conventional pitch roof made of massive concrete and acts as a solar air heater. Solar radiation collected into absorber is stored in the roof structure by radiation and convection so that it reduces the nighttime heating load through the roof. Another part of the energy is also transmitted to internal air drawn into the channel and is then introduced Into the room. To analysis the system, the energy balance equations are developed and are solved using a finite difference method. The calculation results show a good agreement with the measured ones obtained from our experiments. From the results, it is seen that the thermal storage roof with the air circulation system reduces significantly the conductive heat loss compared with that for the conventional roof and has the instantaneous solar collection efficiency of about 30%.

• KIEAE Journal
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• 제12권4호
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• pp.97-104
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• 2012

A phase-change material is a substance with a high heat of fusion which, melting and freezing at a certain temperature, is capable of storing and releasing large amounts of energy. Heat is absorbed or released when the material changes from solid to liquid. Therefore, PCMs are classified as latent heat storage (LHS) units. The purpose of this study is to analyze PCM wallboard design parameters using dynamic energy simulation. Among the factors of PCM, melting temperature, latent heat, phase change range, thermal conductivity are very important element to maximize thermal energy storage. In order to analyze these factors, EnergyPlus which is building energy simulation provided by department of energy from the U.S is used. heat balance algorithm of energy simulation is conduction finite difference and enthalpy-temperature function is used for analyzing latent heat of PCM. The results show that in the case of melting temperature, the thermal energy storage could be improved when the melting temperature is equal to indoor surface temperature. It seems that when the phase change range is wide, PCM can store heat at a wide temperature, but the performance of heat storage is languished.