• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권3호
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• pp.146-152
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• 2004

Cost effective simulation schemes for Wind Power Generation Systems (WPGS) considering wind turbine types, generators and load capacities have been strongly investigated by researchers. As an alternative, a true weather condition based simulation method using a real-time digital simulator (RTDS) is experimented in this paper for the online real-time simulation of the WPGS. A stand-alone WPGS is, especially, simulated using the Simulation method for WPGS using Real Weather conditions (SWRW) in this work. The characteristic equation of a wind turbine is implemented in the RTDS and a RTDS model component that can be used to represent any type of wind turbine in the simulations is also established. The actual data related to weather conditions are interfaced directly to the RTDS for the purpose of online real-time simulation of the stand-alone WPGS. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme. The results also signify that the cost effective verification of efficiency and stability for the WPGS is possible by the proposed real-time simulation method.

• 대한조선학회논문집
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• 제59권4호
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• pp.200-206
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• 2022

This study is to develop database by an experimental method for the development of condition based maintenance for auxiliary equipment in marine engine systems. Existing ships have been performing regular maintenance, so the actual measurement data development is very incomplete. Therefore, it is best to develop a database on land tests. In this paper, a database developed by an experimental method is presented. First, failure case analysis and reliability analysis were performed to select a failure mode. For the failure simulation test, a test bed for land testing was developed. The failure simulation test was performed based on the failure simulation scenario in which the failure simulation test plan was defined. A 1.5TB failure simulation database has been developed, and it is expected to serve as a basis for ship failure diagnosis and prediction algorithm model development.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1151-1154
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• 2004

In this study, we presented a novel method to calculate unknown voltages on the floating electrodes introduced in a unit pixel of TFT-LCDs using three-dimensional molecular director simulation. For the simulation of the potential distribution profiles generated under the influence of the floating electrodes, we used the floating boundary condition on the surface enclosing the floating electrodes. The constraint for the floating boundary condition was derived from the charge neutrality condition about the floating electrodes disconnected from voltage sources. For the pixel with the floating electrodes patterned between the pixel and the data electrodes, we simulated the molecular director and the potential distribution in three-dimension, and then observed the location of the disclination lines around the edge of the pixel electrode. As a result, it was revealed that the floating electrodes significantly affect the electro-optical characteristics such as the location of the disclination line.

• 환경영향평가
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• 제21권1호
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• pp.133-142
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• 2012

Convection Current Circulation System(CCCS) in stratified reservoir controls development of anaerobic condition and algal bloom during summer. In order to increase the CCCS effectiveness, we analyze diverse design parameters to make optimize the flow pattern in reservoir. In this study, we interpret the internal flow with installation and operation condition of CCCS based on CFD in reservoir. Design variables of CCCS is reservoir depth, stratification strength, distance of between CCCS and so on. Since reservoir depth and stratification strength in variables is depending on natural phenomenon, we evaluated current circulation effect by distance of CCCS and proposed the optimal design condition using CFD simulation. Flow and diffusion changes in water body was assessed by temperature and dye test. Changes in water floor temperature at 40m intervals was slowly descending over 37 hours. Dye diffusion simulation at 60m intervals, the radius of the spread between two devices were overlapped after 12 hours.

• 대한설비공학회지:설비저널
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• 제14권1호
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• pp.1-11
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• 1985

Solar/absorption cooling system was analyzed and its operating condition was examined. For the system, the optimum size of absorption refrigerator and collector area should be determined. As the temperature of water supplied to the generator increases, the collector efficiency decreases whereas the coefficient of performance of absorption refrigerator increases up to a certain point, and vice versa for decreasing of the temperature of water supplied to the generator . Thus if the reeling load is given, the appropriate operating condition can be determined between the two opposing trends by simulation program. As an example of the simulation, the case of Jejudo province was studied. Under the conditions (such as weather data and prices of components, etc.) given en the sample calculation, the result shows that the optimum temperature of water supplied to the generator turned out to be $80.3^{\circ}C$, and still shows a large economical disadvantage in present stage compared to the case of conventional vapor compression cooling/heating combined heat pump system.

• 한국해양공학회지
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• 제13권4호통권35호
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• pp.45-54
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• 1999

Non destructive test is applied to revise mechanical strength and assume material strength or defect of material, equipment and structure, instead of fracture test. Especially, ultrasonic test has the characteristics such as an excellent permeability high-sensitiveness to fine defect and an almost exact measurement for position, size and direction of inner defect which differ from other non destructive tests. In this study, the program is developed to evaluate optimal testing condition, to distinguish obstacle echo and defect position. This program on the basic of Ray-Tracing model shows generation and processing of ultrasonic pulse. The simulation is compared with testing in the 3 cases of an oblique angle transducer like $45^{\circ},\;60^{\circ}\;and\;70^{\circ}$. The test result for all conditions is well compared with simulation result when relative not is within $0.1{\sim}7.2%$. And the course of several echos is simply assumed through simulation.

• KIEAE Journal
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• 제15권4호
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• pp.5-11
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• 2015

Purpose: Recently, renewable energy system has been widely used to reduce the energy consumption and CO2 emission of building. A photovoltaic/thermal(PVT) system is a kind of efficient energy uses, which is combined with photovoltaic module and solar thermal collector. PVT system removes heat from PV module by through thermal fluid to raise the performance efficiency of the PV system. However, though PVT system has the merit of the improved efficiency in theoretical approach, there have been few performance analysis for PVT system using the dynamic energy simulation. In this study, in order to establish the optimum design method of this system, simulation was conducted by using individual system modules. Method: For the dynamic simulation, TRNSYS17 was used and local weather data was utilized. Furthermore, the system performance in various installation condition was calculated by case studies. Result: As a result, the amount of electric generation and heat production in each case was found by the simulation. The gap of system performance was also evident according to the installation condition.

• 한국자동차공학회논문집
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• 제5권2호
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• pp.94-110
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• 1997

In the present study, a mean torque predictive model has been proposed and experimentally validated. It includes induction air mass model, fuel delivery model and mean production mode. Air induction and fuel delivery model considering dynamic behaviors of air induction and fuel delivery were proposed to predict the air-fuel ratio excursions under transient condition. Torque function model reflects thermal efficiency, volumetric efficiency, friction and effect of spark timing. In the spark timing model, knock limit and acceleration retard are included. Experiments were carried out to validate the simulation model for the step changes of throttle at constant engine speed. The results show reasonable agreements between simulation and experiment at fully warmed condition. Using this model, fueling strategies are varied with fast throttle open and it can predict air-fuel ratio excursion and IMEP.

• 한국군사과학기술학회지
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• 제6권1호
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• pp.30-38
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• 2003

The measurement on the working gas flow in the closed cycle diesel engine is insufficient to Identify its operating condition because of lack of sensors available. For this reason, the determination of optimum operating condition and controller parameters requires heavy experimental efforts. A simulation program is developed to minimize the experimental efforts. For the development of the simulation program, mathematical models are derived based on the physical laws and linear regression. The validity of the simulation program is demonstrated using the measured data of the closed cycle diesel engine.

• 해양환경안전학회지
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• 제17권4호
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• pp.383-389
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• 2011

선박 성능과 항해 안전의 관점에서 선박조종 특성을 아는 것은 선박 설계에서 중요한 일이다. IMO 규정에 의하면 만재 적하된 even 조건(트림=0)에서 몇가지 선박 조종 기준이 제시되어 있다. 그러나 선박은 일반적으로 항상 만재 적재 조건으로 운항되지 않는다. 따라서 선박이 IMO 규정을 만족시키고, 모든 적재 조건에서 안전하게 항행하도록 하기 위해 다양한 적재 조건에서 선박 조종 특성을 추정해야 한다. 본 논문에서 우리는 실선 실험과 시뮬레이션을 수행하여 조종특성을 조사하였다. 시뮬레이션 결과와 비교하였을 때 실선실험은 시뮬레이션 값 및 이전 연구와 그 경향이 일치한다. 실 해역에서 얻은 조종실험 데이터가 선박 조종성능 추정에 활용 될 수 있음을 확인하였고, 실시한 실해역 실험을 통하여, 선박 운항 상태에 따른 조종성의 변화를 추정할 수 있었다.