• 대한기계학회논문집A
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• 제27권3호
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• pp.381-386
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• 2003

Gradually engineering designers are determined based on computer simulations. Modeling of the computer simulation however is too expensive and time consuming in a complicate system. Thus, designers often use approximation models called metamodels, which represent approximately the relations between design and response variables. There arc general metamodels such as response surface model and kriging metamodel. Response surface model is easy to obtain and provides explicit function. but it is not suitable for highly nonlinear and large scaled problems. For complicate case, we may use kriging model that employs an interpolation scheme developed in the fields of spatial statistics and geostatistics. This class of into interpolating model has flexibility to model response data with multiple local extreme. In this study. metamodeling techniques are adopted to carry out the shape optimization of a funnel of Cathode Ray Tube. which finds the shape minimizing the local maximum principal stress Optimum designs using two metamodels are compared and proper metamodel is recommended based on this research.

• 한국컴퓨터정보학회논문지
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• 제4권2호
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• pp.70-79
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• 1999

이동 데이터베이스 체계에서 거래처리 기법은 정적 조정자에 의한 거래처리와 조정자 이주에 의한 거래처리 기법이 있다. 조정자 이주에 의한 거래처리 기법은 거래서비스 통화채널 변경이 이루어졌을 경우에 새로운 데이터베이스 서버에서 그 거래를 계속 처리해야한다는 조정자 이주 원리를 적용하는 것이고 조정자 정착에 의한 거래처리 기법은 거래서비스 통화채널 변경이 이루어졌을 경우라 할 지라도 그 거래를 시작한 데이터베이스 서버에 의하여 처리해야 한다는 정적 조정자 원리를 적용하는 것이다. 본 논문에서 이동 거래처리 기법들의 공정한 성능 비교연구를 위하여 기법들과 독립적인 성능모델을 개발하였다. 그리고 이동 거래처리 기법의 성능 모델을 자세히 설명하였고 성능평가의 신뢰성을 위하여 얻어진 모의실험 결과를 자세히 설명하였다. 결국, 이동 거래처리 기법들은 데이터베이스 서버에서 거래처리를 위한 메시지 이동을 최소화함으로서 시스템 성능을 향상시킬 수 있다.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2298-2306
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• 2017

A PMS (Power Management System) controls vessel's power systems to improve the system efficiency and to protect a blackout condition. The PMS should be developed with considering the type and the capacity of the vessel's power system. It is necessary to test the PMS functions developed for vessel's safe operations under various sailing situations. Therefore, the function tests in cooperation with practical power systems are required in the PMS development. In this paper, a hardware-in-the-loop (HIL) simulator is developed for the purposes of the PMS function tests. The HIL simulator can be more cost-effective, more time-saved, easier to reproduce, and safer beyond the normal operating range than conventional off-line simulators, especially at early stages in development processes or during fault tests. Vessel's power system model is developed by using a MATLAB/SIMULINK software and by communicating between an OPAL-RT's OP5600 simulator. The PMS uses a Modbus communication protocol implemented using LabVIEW software. Representative tests of the PMS functions are performed to verify the validity of the proposed HIL-based test platform.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.111-116
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• 1999

Over the last few years, there has been a growing interest in quantitative representation of heat transfer and fluid flow phenomena in weld pools in order to relate the processing conditions to the quality of the weldment produced and to use this information for the optimization and robotization of the welding process. Normally, a theoretical model offers a powerful alternative to estimate the important input parameters and to calculate the effects of varying any of parameters. To solve this problem, a transient 2D(two-dimensional) heat conduction and a transient 2D axisymmetric heat and fluid model were developed for determining weld bead geometry and temperature distribution for the GMA(Gas Metal Arc) welding process. The equation was solved using a general thermofluid-mechanics computer program, PHOENICS code, which is based on the SIMPLE algorithm. The simulation results showed that the calculated bead geometry from two developed models reasonably agree with the experiment result.

• 한국시스템다이내믹스학회:학술대회논문집
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• 한국시스템다이내믹스학회 2003년도 하계학술대회발표논문집
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• pp.1-24
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• 2003

The purpose of this paper was developing a development density control model for urban growth management, using system dynamics modeling. The density control model was developed to see how urban growth, transition, and decay occur depending on the interaction among population, houses, industry structure, land and urban infrastructure such as road, water supply, and sewage treatment facilities. Suggesting adequate level of development density control using the model was another purpose of this paper. The model was applied to An'yang city to estimate the maximum number of population, industry structures, houses, and cars that can be adequately sustained with the current An'yang city's infrastructur capacity. The computer simulation results shows that the city is overpopulated by some 90,000 people. To reduce the population to the adequate level that the current urban infrastructure can sustain, the current city regulation on floor area ratio are needed to be strengthened at least 20 to 35%.

• 한국자동차공학회논문집
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• 제5권4호
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• pp.39-47
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• 1997

The focus of this research is to set up and describe the mathematical derivation of an automobile power-assisted rack and pinion steering system dynamics. The mathematical model of the power steering system dynamics with a 5 DOF linear vehicle model will be used in the computer simulation and evaluated comparing with the experimental results. This model is flexible to accommodate different vehicles through simple parameter changes. The developed mathematical model will attempt to provide enhanced driver realism to a Systems Technology, Inc. driving SIMulator(STISIM).

• 한국식품영양과학회지
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• 제20권6호
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• pp.572-581
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• 1991

무우의 염절임시 무우내로의 소금의 침투량을 예측할 수 있는 모델을 수립하고자 각각 5%, 10%, 15% 소금용액의 농도, 10, 20, $30^{\circ}C$ 온도에서 시간당 무우내 소금의 침투량과 수분의 변화를 측정하였다. 시간에 따른 무우내 소금의 침투량은 ln 함수를 따랐고 소금용액의 농도와 온도에 따른 무우내 소금의 침투량은 linear 한 관계를 나타내었다. 각각의 시간, 소금용액의 농도, 온도에 따른 무우내 소금의 침투량 예측 모델은 SPSS 통계 package중의 regression program을 이용하여 model식을 수립하였다. 무우내로의 소금의 확산도는 Fick 제2법칙의 적절한 확산식에서 computer simulation을 통해서 확산도를 계산하였다. 무우내로의 소금의 확산도는 소금용액의 농도가 즈가함에 따라 커지고 예측할 수 있는 model식은 회귀분석을 통해 수립하였다. 무우내로의 소금의 침투량과 무우밖으로의 탈수량과의 관계를 규명하기 위해 Flux ratio(${\Delta}W/{\Delta}S$)을 구해 본 결과 1보다 조금 큰 값을 나타내어 탈수량이 소금의 침투량보다 다소 많음을 알 수 있었다.

• ETRI Journal
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• 제6권3호
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• pp.9-16
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• 1984

This paper describes $\mu$-law PCM/ADPCM Code Conversion System. The system algorithm is computer-simulated, and with the result of simulation the system is designed by using the Am 2900 family's Bit-Slice Microprocessors which have a high-speed processing power. The ADPCM algorithm is based on Jayant's model and the converting algorithm between $\mu$-law PCM and linear PCM is developed according to the CCITT Recommendation G. 711.

• International Journal of Precision Engineering and Manufacturing
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• 제4권4호
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• pp.32-38
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• 2003

An analytical model of the interference phenomena in the centerless grinding process is developed to investigate their effects on the roundness profile of a centerless ground workpiece. In this work, the regulating wheel and work-rest blade interferences are modeled as a single point contact. The grinding wheel interference is modeled as multiple points contact because material removal is determined by the duration of contact. The computer simulation results show good agreement with the experimental data. From this work, the existence and effects of the interference phenomena in the centerless grinding process are found.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.220-220
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• 2015

Water, energy, and food security already became a risk that threatens people around the world. Increasing of resources demand, rapid urbanization, decreasing of natural resources and climate change are four major problems inducing resources' scarcity. Indeed, water, energy, and food are interconnected each other thus cannot be analyzed separately. That is, for simple example, energy needs water as source for hydropower plant, water needs energy for distribution, and food needs water and energy for production, which is defined as W-E-F nexus. Due to their complicated linkage, it needs a computer model to simulate and analyze the nexus. Development of a computer simulation model using system dynamics approach makes this linkage possible to be visualized and quantified. System dynamics can be defined as an approach to learn the feedback connections of all elements in a complex system, which mean, every element's interaction is simulated simultaneously. Present W-E-F nexus models do not calculate and simulate the element's interaction simultaneously. Existing models only calculate the amount of water and energy resources that needed to provide food, water, or energy without any interaction from the product to resources. The new proposed model tries to cope these lacks by adding the interactions, climate change effect, and government policy to optimize the best options to maintain the resources sustainability. On this first phase of development, the model is developed only to learn and analyze the interaction between elements based on scenario of fulfilling the increasing of resources demand, due to population growth. The model is developed using the Vensim, well-known system dynamics model software. The results are amount of total water, energy, and food demand and production for a certain time period and it is evaluated to determine the sustainability of resources.