• 전기의세계
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• 제43권11호
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• pp.22-29
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• 1994

본 고에서는 1995년 말 상기 연구 과제에서 개발될 새로운 디지탈 분산 제어기를 실제 발전소와 가장 비슷한 환경에서 모의 실험을 할 수 있도록 해주는 실시간에 동작하는 화력발전소 시뮬레이터를 개발한 예에 대하여 설명하고자 한다. 먼저 2절에서는 본 시뮬레이터의 전체 구조를 간략하게 도시하고, 3절에서는 본 시뮬레이터가 모사하고자 하는 화력발전소의 수학적 모델에 대하여 간략하게 서술하며, 4절에서는 본 시뮬레이터의 상세한 구조를, 5절에서는 PC로 구성된 간이 디지탈 제어기와 결합된 모의 실험 결과를 각각 설명한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2000년도 추계 학술대회논문집
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• pp.66-71
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• 2000

In the present study a numerical simulation is performed on a natural convection inside a square cavity with a vibrating bottom wall. The heat transfer coeffcients for various amplitudes of the bottom wall vibration were compared to the case without the bottom wall excitation. From the results, it is seen that the local temperature distribution in a cavity becomes more uniform as the amplitude of the bottom wall vibration is increased. Also, it was seen that the heat transfer coefficient increased on the heating wall as the applied amplitude increased.

• 한국전산유체공학회지
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• 제4권1호
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• pp.34-40
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• 1999

Drag reduction on vehicles are the main concern for the body shape designers in order to lower the fuel consumption rate and to aid the driving stability. The drag of bluff bodies like transportation vehicles is mostly pressure drag due to the flow separation, which can be minimized by controlling the location and size of the separation bubble. In the present study, the TURBO-3D code is incorporated with optimal algorithm based on analytical approximation method to obtain an optimal afterbody shape of the MIRA Model corresponding to the lowest drag coefficient. For this purpose three mutually independent afterbody angles are chosen as design variables, while the drag coefficient is chosen as an objective function. It is demonstrated in the present study that an optimal body shape having the lowest drag coefficient which is about 6% lower than that of the original shape has been successfully obtained within number of iterations of tile optimal design loop.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.608-609
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• 2008

An alternator which converts mechanical rotating energy into electric energy is an important component of a vehicle. It operates in broad range from 3000 RPM to 18000 RPM. So, sufficient flow rate and low noise are needed in such broad operating range for a cooling fan of this alternator. In current study, the cooling fan of an alternator is developed through DFSS process and numerical analysis. In order to calculate flow rate and noise level, SC/Tetra and FlowNoise S/W are used respectively, for a new developed fan, compared with original model, numerical result shows 3 dBA reduction and measured value shows 4 dBA reduction.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.333-336
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• 1991

In this paper, Hopfield & Tank model-like artificial neural network structure is proposed, which can be used for the optimal path planning problems such as the unit commitment problems or the maintenance scheduling problems which have been solved by the dynamic programming method or the branch and bound method. To construct the structure of the neural network, an energy function is defined, of which the global minimum means the optimal path of the problem. To avoid falling into one of the local minima during the optimization process, the simulated annealing method is applied via making the slope of the sigmoid transfer functions steeper gradually while the process progresses. As a result, computer(IBM 386-AT 34MHz) simulations can finish the optimal unit commitment problem with 10 power units and 24 hour periods (1 hour factor) in 5 minites. Furthermore, if the full parallel neural network hardware is contructed, the optimization time will be reduced remarkably.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.455-456
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• 2008

우리나라 전력산업은 구조개편 이전에는 수직독점이면서 공기업인 한국전력공사 단일기업의 형태로 운영되어왔다. 2001년 한전의 발전사업 부문이 6개의 발전사업자로 분리되었고, 전력산업은 단계적으로 시장구조로 변모하는 과정 중에 있다. 이러한 전력산업의 구조 개편은 전력수급계획에도 영향을 미쳤으며 점차 '시장참여자 성격'이 강화되는 방향으로 진행되고 있음을 확인할 수 있다. 2006년의 제3차 전력수급기본계획에 이후 목표계획의 수립, 건설의향의 평가, 연료제약의 실질적 반영 등 다양한 시나리오 분석과 지역별 수급분석 등이 주요이슈가 되면서, 기존에 활용했었던 비용최소화 모형에 의존한 계획기법에 한계가 존재하게 되었다. 본 논문에서는 변화된 전력산업 환경에 적합한 발전투자계획의 방법론으로서 시장 기반의 전원계획 방법론을 제시하고자 한다.

• 한국전산유체공학회지
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• 제5권3호
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• pp.16-22
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• 2000

In the present study a method of computing fluid-structure interaction is presented to simulate the deformation shape of an oil fence which is used to contain or to divert the split oil in sea water. The computation is performed by taking into account of the force and moment balance in each computational element of the oil fence. The forces and moments acting on each element of the structure is computed from the flow analysis, which in turn is used to predict deformed shape of the structure until the procedure converges. The flexibility of the oil fence was also considered in the analysis. It is shown from the present study that the predicted deformed shapes agree quite well with the available experiment data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.524_525
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• 2009

전력시장의 효율적인 운영을 위한 전력산업 구조개편은 전 세계적으로 진행되고 있다. 우리나라의 경우 발전부문의 분할과 부분적인 경쟁의 도입되고 있다. 따라서 발전설비투자에 있어서 정부의 역할이 축소되고 점차 시장 기제 속에서 발전사업자 각각의 투자권한이 강해지고 있는 실정이다. 구조개편 이전에는 일반적으로 정부가 장기적인 전력 공급의 안정을 위해 전력공급계획을 수립하고, 독점회사인 한국전력공사가 이에 따른 발전설비투자를 시행하였다. 그러나 전력산업 구조개편 이후, 새로운 전력수급기본계획을 수립하였다. 이전과 가장 큰 차이는 발전사업자가 발전설비를 투자하는데 있어 자유롭게 사업계획을 세울 수 있게 되었다는 점이다. 본 논문에서는 발전분할 전후의 투자효율성을 비교하는 방법론을 제시하고, 그 프레임을 한국 전력시장에 적용시켜보았다.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1419-1426
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• 2002

An experimental study was made to elucidate critical heat flux(CHF) characteristics in a two-phase concentric-tube thermosyphon. The experiment was performed by using saturated water, over the experimental range of configuration: inner diameter of heated outer tube D=12mm, outer diameter of unheated inner tube do=3 to 10mm and heated tube length L=100 to 1000mm. The experiment shows that the CHF is enhanced with increase in the inner tube diameter, and that the CHF decreases beyond a certain diameter of the inner tube. There is an optimum diameter for inner tube that maximizes the CHF, for each tube length and test liquid. The CHF maximum is about two to eight times as large as that without an inner tube. For a large inner tube, the CHF characteristics is similar to that for natural convective boiling in a vertical annular tube.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.896-901
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• 2002

The sound absorption coefficients for multiple layer perforated plate systems containing several compartments with airspaces and porous absorbing materials are estimated using the transfer matrix method developed in the previous paper. The absorption coefficients from transfer matrix method agree well with the values measured by the two-microphone impedance tube method for various combinations of perforated plates, airspaces or porous materials. Based on these results, a guidance for the design of multiple layer perforated plate systems combined with airspaces and porous absorbing materials is discussed in detail.