• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.81-84
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• 2002

An approach for predicting the effective thermal conductivities of fiber-reinforce composite has been developed based on a thermal-electrical analogy. The unit cell of the composite laminate is divided into regular volume elements and the material properties have been given to each element. By constructing the series-parallel thermal resistance network, the thermal conductivities of composite both in-plane and out-of-plane direction have been predicted. Graphite/Epoxy composite is used for a balanced plain-weave composite laminate. By comparing the predicted results and the previous works, good agreement has been found.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.52-55
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• 2002

This paper examines the effective thermal conductivity of 3-D braided glass/epoxy composites. 3-D braided composites have a number of advantage over conventional laminate composites, including through-thickness reinforcement, and high damage tolerance and processability. The thermal properties of composites depend primarily on the microstructure of the braided preform and properties of constituent materials. A thermal resistance network model based on structure of the braided preform is proposed by using thermal-electrical analogy. In order to affirm the applicability theses solutions, thermal conductivities of 3-D braided glass/epoxy composites are measured

• 대한기계학회논문집A
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• 제30권4호
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• pp.409-419
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• 2006

The actuating performance of plate-type unimorph piezoelectric composite actuators having various stacking sequences was evaluated by three dimensional finite element analysis on the basis of thermal analogy model. Thermal residual stress distribution at each layer in an asymmetrically laminated plate with PZT ceramic layer and thermally induced dome height were predicted using classical laminated plate theory. Thermal analogy model was applied to a bimorph cantilever beam and LIPCA-C2 actuator in order to confirm its validity. Finite element analysis considering thermal residual deformation showed that the bending behavior of piezoelectric composite actuator subjected to electric loads was significantly different according to the stacking sequence, thickness of constituent PZT ceramic and boundary conditions. In particular, the increase of thickness of PZT ceramic led to the increase of the bending stiffness of piezoelectric composite actuator but it did not always lead to the decrease of actuation distance according to the stacking sequences of piezoelectric composite actuator. Therefore, it is noted that the actuating performance of unimorph piezoelectric composite actuator is rather affected by bending stiffness than actuation distance.

• 설비공학논문집
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• 제24권4호
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• pp.306-314
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• 2012

Several numerical or analytical models have been proposed to analyze the thermal response of vertical ground heat exchangers (GHEX). However, most models are valid only after several hours of operation since they neglect the heat capacity of the borehole. Recently, the short time response of the GHEX became important in system simulation to improve efficiency. In this paper, a simple new method to evaluate the short time response of the GHEX by using an analogy model of electric circuit transient analysis was presented. The new transient heat exchanger model adopting the concept of thermal capacitance of the borehole as well as the steady-state thermal resistance showed the transient thermal resistance of the borehole. The model was validated by in-situ thermal response test and then compared with the DST model of the TRNSYS program.

• 조명전기설비학회논문지
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• 제26권5호
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• pp.1-12
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• 2012

In order to reduce energy consumption and greenhouse gas emission in building domain, thermal insulation of building is being enhanced. In a well insulated and tightened environment, internal heat gain caused by solar radiation, luminaires, electronic appliances and metabolism can be more important to thermal condition of building. This paper presents mathematical/physical models of quasi-adiabtic room and lighting fixtures using heat balance equation and thermal-electric analogy to quantify and modelize the heat gain due to luminaires. Experimental results are used to identify thermal parameters of theoretical models. And simulation results of models using Matlab/Simulink are conducted to verify the models and to investigate the thermal effect of lighting fixtures into quasi-adiabatic room.

• 대한공간정보학회지
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• 제19권2호
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• pp.19-27
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• 2011

본 연구의 목적은 기후변화에 따른 잠재 산림분포 예측에 이용되는 기상 자료의 효과적인 구축 및 규모변환(Down Scaling) 방법을 제시 하는 것이다. 잠재 산림분포 예측을 위해 한국형 산림 분포 모형 TAG(Thermal Analogy Group)의 예측 방법과 HyTAG(Hydrological and Thermal Analogy Group)에서 정의한 식생 기능성 유형(PFT: Plant Functional Types)을 함께 적용하였다. 이를 위해 20km 공간해상도의 기상자료를 1km의 공간해상도에 부합하도록 보간 하였다. 이러한 보간 및 규모변환의 한 가지 방법으로 고도에 따른 기온감율을 적용 및 비적용하여 각각의 과거 잠재 산림분포를 예측하였다. 현존 산림분포도와 비교한 정확도 검증에서 기온감율을 적용한 잠재 산림분포가 약 38% 더 정확한 것으로 나타났다.

• 한국산림과학회지
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• 제100권2호
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• pp.256-265
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• 2011

본 연구에서는 Intergovernmental Panel on Climate Change(IPCC) 기후변화 시나리오 A2와 B1에 따른 산림분포 취약성을 평가하였다. 산림분포 취약성은 한국형 산림 생태계 분포 모델 Thermal Analogy Groups(TAG) 의 산림분포예측 방법과 Hydrology Thermal Analogy Groups(HyTAG)에서 정의한 식생유형을 이용하여 기후 변화에 따른 잠재 식물상(Plant Functional Type: PFT)의 분포 변화를 기후변화 민감성과 적응성으로 나누어 평가되었다. 그 결과, 산림분포가 취약한 지역의 면적은 A2 시나리오에서 전체 국토 면적의 30.78%, B1에서는 2.81%로 나타났다. 행정구역별 취약성 평가 결과는 부산이 A2 시나리오에서 가장 취약하고 대구가 B1 시나리오에서 가장 큰 취약성을 나타냈다. 미래 발전 방향에 따라서 상이하게 구축된 시나리오 별 산림 분포 취약성 결과는 앞으로 산림 분야 적응대책 수립에 중요한 자료로 이용될 것이다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.48-51
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• 2002

This paper predicted the thermal conductivity of spun carbon/phenolic composites by the thermal resistance method. This method uses the analogy between the diffusion of heat and electrical charge. To verify the theoretical predictions, the thermal conductivity of spun carbon/phenolic composites was examined experimentally. The reported thermal conductivities of graphite/epoxy composite of a eight harness satin laminate was used of the comparison with the prediction values of the model and it was noticed that a good agreement has been found.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.141.2-141.2
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• 2005

• Smart Structures and Systems
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• 제5권6호
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• pp.591-612
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• 2009

New insights are presented in simplified modeling and analysis of free vibrations of piezoelectric - based smart structures and systems. These consist, first, in extending the wide used piezoelectric-thermal analogy (TA) simplified modeling approach in currently static actuation to piezoelectric free-vibrations under short-circuit (SC) and approximate open-circuit (OC) electric conditions; second, the popular piezoelectric strain induced - potential (IP) simplified modeling concept is revisited. It is shown that the IP resulting frequencies are insensitive to the electric SC/OC conditions; in particular, SC frequencies are found to be the same as those resulting from the newly proposed OC TA. Two-dimensional plane strain (PStrain) and plane stress (PStress) free-vibrations problems are then analyzed for above used SC and approximate OC electric conditions. It is shown theoretically and validated numerically that, for both SC and OC electric conditions, PStress frequencies are lower than PStrain ones, and that 3D frequencies are bounded from below by the former and from above by the latter. The same holds for the modal electro-mechanical coupling coefficient that is retained as a comparator of presented models and analyses.