• Solar Energy
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• v.12 no.1
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• pp.72-80
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• 1992

This paper is concerned with the accurate estimation of the thermal mass effect on the variation of indoor temperature for residential buildings. To carry out the analysis here, the method called "PSTAR(Primary and Secondary Terms Analysis and Renormalization)" has been extensively used. This method was originally developed by the National Renewable Energy Laboratory(NREL) in the United States. The test results reported here represent two extreme cases of the interior thermal mass, which demonstrate its effect on the interior thermal environment as well as on the overall thermal behavior of the building structure. The monthly heating and cooling loads are also extrapolated by using the renormalized model, which are crucial in designing and refurbishing HVAC systems for the building.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.471-478
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• 2002

초음파를 사과의 비파괴 품질판정에 이용하기 위한 기초연구로서 계측된 저장기간에 따른 사과의 초음파 특성과 본 연구에서 계측된 사과의 기계적 특성을 이용하여 초음파에 의한 사과의 탄성계수 및 생물체항복강도 예측모델을 개발하고자 하였으며, 결론은 다음과 같다. 1. UTM을 이용하여 사과의 기계적 특성치를 분석하여 생물체항복점, 생물체항복변형량, 생물체항복강도, 파괴점, 극한변형량, 극한강도 및 탄성계수 등을 구하였다. 2. 사과의 기본 물성, 초음파 특성과 기계적 특성값 들을 분석한 결과 사과의 질량, 체적, 시간영역의 진폭(PTP), 제3영역 에너지 스펙트럼 밀도함수가 기계적 특성 중 생물체항복강도, 탄성계수와 높은 상관성이 있는 것으로 나타났다. 3. 사과의 저장 기간, 질량, 체적, Peak-to-peak, 제3영역의 에너지값 등 5개의 독립변수를 가지는 다중선형회귀모형으로 사과의 탄성계수 및 생물체 항복강도 예측모형을 개발하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.47-52
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• 2011

In this paper, we describe the development of a finite-element model for seismic qualification. This paper presents finite-element analysis model of the electronic enclosure to be used at Arkansas nuclear power plant, USA. The verified model predicts natural frequencies within 5% error for all major modes below 50 Hz. The finite element lumped mass approach and the finite element stiffness approach using the COSMOSM finite element code is applied for static, eigenvalue, and dynamic analyses of the mathematical model of this system. The FEM model indicates that the stress levels corresponding to the specified loading conditions are below the allowable stress levels that have been specified in the AISC Code. The findings conclude that the electronic enclosure will withstand the seismic levels stated in the reference documents.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.44-51
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• 2016

The powder core, conventionally fabricated from iron particles coated with insulator, showed large eddy current loss under high frequency, because of small specific resistance. To overcome the eddy current loss, the increase in the specific resistance of powder cores was needed. In this study, copper oxide coating onto electrically conductive iron particles was performed using a planetary ball mill to increase the specific resistance. Coating factors were optimized by the Response surface methodology. The independent variables were the CuO mass fraction, mill revolution number, coating time, ball size, ball mass and sample mass. The response variable was the specific resistance. The optimization of six factors by the fractional factorial design indicated that CuO mass fraction, mill revolution number, and coating time were the key factors. The levels of these three factors were selected by the three-factors full factorial design and steepest ascent method. The steepest ascent method was used to approach the optimum range for maximum specific resistance. The Box-Behnken design was finally used to analyze the response surfaces of the screened factors for further optimization. The results of the Box-Behnken design showed that the CuO mass fraction and mill revolution number were the main factors affecting the efficiency of coating process. As the CuO mass fraction increased, the specific resistance increased. In contrast, the specific resistance increased with decreasing mill revolution number. The process optimization results revealed a high agreement between the experimental and the predicted data ($Adj-R^2=0.944$). The optimized CuO mass fraction, mill revolution number, and coating time were 0.4, 200 rpm, and 15 min, respectively. The measured value of the specific resistance of the coated pellet under the optimized conditions of the maximum specific resistance was $530k{\Omega}{\cdot}cm$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.271-281
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• 2005

The effects of radiation damping is used to compensate the truncated boundary which is relatively close to the structure-fluid interface in the fluid element surrounding the submerged structures. An efficient ring element is presented to model the shell and fluid element which fully utilizes the characteristics of the axisymmetry. The computational model uses the technique which separate the meridional shape and circumferential wave mode and gets similar result with the exact solution in the eigenvalues and the earthquake analysis. The fluid-structure interaction techniques is developed in the finite element analysis of two dimensional problems using the relations between pressure, nodal unknown acceleration and added mass assuming the fluid to be invicid, incompressible and irrotational. The effectiveness and efficiency of the technique is demonstrated by analyzing the free vibration and seismic analysis using the added mass matrix considering the structural deformation effect.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.99-108
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• 2005

This paper represents an efficient modeling method of a suspension system for the vehicle dynamic simulation. The suspension links are modeled as composite joints. The motion of wheel is defined as relative one degree of freedom motion with respect to car body. The unique relative kinematic constraint formulation between the car body and wheel enables to derive equations of motion in terms of wheel vertical motion. Thus, vehicle model has ten degrees of freedom. By using velocity transformation method, the equations of motion of the vehicle is systematically derived without kinematic constraints. Various vehicle simulation such as J-turn, slowly increasing steer, sinusoidal sweep steer and bump run has been performed to verify the validity of the suggested vehicle model.

• Journal of the korean Society of Automotive Engineers
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• v.16 no.3
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• pp.19-29
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• 1994

본 연구에서는 상태방정식과 출력방정식에 외란항을 포함하게 된다. 최적조건을 이용하여 외란항을 포함한 리카티 방정식을 유도하고 그로부터 제어로직을 얻을 수 있다. 본 연구에서의 차량 모델링은 스프링 위 질량 3자유도와 스프링 아래 질량 4자유도 운전석의 연직방향 1자유도를 포함한 총 자유도의 선형모델로 하였다. 또 본 연구에서는 예견제어를 이용하였는데 차량앞에 미리 도로면의 정보를 인식할 수 있는 가상적인 측정장치가 있다고 가정하였다. 결과에서는 기존의 수동형 현가장치와 최적제어를 이용한 능동형 현가장치를 구분하고, 예견시간에 따른 차량의 성능을 비교 분석하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.31-32
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• 2022

In Early vessels did not provide an exact equation for preventig the capsizing vessels. On land, many vehicle rollover prevention technologies using the steady-state Conrning Equations were developed, which showed better performance than the exiting method at sea. For better performance, It is proposed to improve safety mangement when turning vessel using the Ackerman geometic model-based Cornering Equations in this paper.

• Journal of the Korean Chemical Society
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• v.41 no.3
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• pp.123-129
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• 1997

In order to consider the reduced mass effects on the out-of-plane ring inversion vibration of 1,3-CHD, the vector-based computer program has been written and the kinetic energy expansion function for the large amplitude ring inversion vibration has been calculated using this program. The structural parameters for the calculations have been determined from the ab initio HF/6-31G** calculation. The potential energy function for the out-of-plane ring inversion vibration of 1,3-CHD has been determined from the kinetic energy expansion function and previously reported low-frequency Raman data. The vibrational Hamiltonian calculation including kinetic energy expansion function made it possible to determine the more reliable out-of-plane potential energy function for the ring inversion of 1,3-CHD.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.301-307
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• 2004

An inverse dynamic model of lower limbs is presented to calculate joint moments during gait. The model is composed of 4 segments with 3 translational joints and 12 revolute joints. The inverse dynamic method is based on Newton-Euler formalism. Kinematic data are obtained from 3 dimensional trajectories of markers collected by a motion analysis system. External forces applied on the foot are measured synchronously using force plate. The use of developed model makes it possible to calculate joint moments for variation of parameters.