• 전기학회논문지P
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• 제67권2호
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• pp.112-118
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• 2018

In recent years, decentralized power have been increasing due to environmental problems, liberalization of electricity markets and technological developments. These changes have led to the evolution of power generation, transmission, and distribution into discrete sectors and the division of integrated power systems. Therefore, studies are underway to efficiently supply power and reduce losses to each sector's demand. This is a major concern for system planners and operators, as it accounts for a relatively high proportion of total power, with a transmission and distribution loss of 4-6%. Therefore, this paper analyzes the status of loss management based on the current transmission and distribution loss rate of each country and transmission loss management cases of each national power company, and proposes a loss rate prediction algorithm according to the long-term transmission system plan. The proposed algorithm predicts the demand-based long-term evolution and the loss rate of the grid to which the transmission plan is applied.

• 대한교통학회지
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• 제24권6호
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• pp.89-102
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• 2006

정적 기 종점 통행량을 가정함으로써 갖는 동적 시뮬레이션 모형의 현실 모사 능력의 한계를 극복하기 위하여 동적 기 종점 통행량 추정 모형을 개발하였다 동적 기 종점 통행량 추정은 통행자의 출발시간, 통행수단. 통행경로 선택 행태모형을 결합한 복합통행행태 수요시뮬레이션 모형을 이용하였다 본 연구에서 개발된 수요 시뮬레이션 모형과 기 개발된 공급 시뮬레이션 모형인 LiCROSiM-P를 결합하여 통합 시뮬레이션 모형을 구축하였다. 단속류/연속류가 공존하는 다경로 가로망에서 출발시간/수단선택/통행경로 선택모형은 AGtt(기 종점통행시간의 시뮬레이션 시간과 기대치의 차이 백분율)는 수렴하지 않고, 평균스케줄지체는 안정 상태로 수렴하는 것으로 나타났다. 통합 시뮬레이션 모형은 교통시설공급 변화와 통행자의 속성 변화에 따른 기 종점 통행량 변화 추정과 효과분석이 가능함을 모형의 적용을 통해 제시하였다. 따라서 통합시뮬레이션 모형은 수요관리정책, 교통시설변화, 교통정보제공 등이 가져오는 출발시간, 통행수단, 통행경로변화를 반영한 시스템의 효과분석이 가능하다

• 대한전기학회논문지:전력기술부문A
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• 제51권12호
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• pp.597-602
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• 2002

The restructuring of power industry is still going on all over the world for last several decades. Many kinds of restructuring model have been studied, proposed, and applied. Among those models, power pool is more popular than other. This paper assumes the power pool market structure having competitive generation sector, and a new method is presented to build a bidding strategy in that market. The utilities participating in the market have the perfect information of their cost and price functions, but they don't know which strategy to be chosen by others. To define one's strategy as a vector, we make utility's cost/price functions into discrete step functions. An utility knows only his own strategy, so he estimates the other's cost/price functions into discrete step functions. An utility knows only his own strategy, so he estimates the other's strategy using Nash equilibrium or stochastic methods. And he also has to forecast the system demand. According to this forecasting result, his payoffs can be changed. Considering these all conditions, we formulate a bidding game problem and apply noncooperative game theory to that problem for the optimal strategy or solution. Some restrictive assumption are added for simplification of solving process. A numerical example is given in Case Study to show essential features and concrete results of this approach.

• 한국소음진동공학회논문집
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• 제21권4호
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• pp.365-373
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• 2011

This paper presents the dynamic response and the vibration characteristics for a rail-track supported by discrete springs and dampers. Recently, automatic conveyer system, rail-track, rack-master system demand the soundproof facilities and vibration suppression measures in order to satisfy the strict environmental standards. The equations of motions of the dynamic characteristics for a vibration suppression rail-track under a traveling mass were derived by Galerkin's mode summation method considering gravity, centrifugal force, Coriolis force, inertia force of the moving mass, transverse inertia of the rail-track. Also, numerical results were calculated by Runge-Kutta integration method. In order to investigate vibration characteristics and dynamic responses, modal testing and measurement of the responses of the rail-track were performed. Through the experiment and numerical simulations, numerical results have a good agreement with experimental ones.

• ETRI Journal
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• 제32권1호
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• pp.33-43
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• 2010

The increasing demand for non-sinusoidal currents affects the quality of distribution networks. Harmonic detection is a crucial step in the cancellation of those components by active power filters. In this paper, the discrete cosine transform (DCT) is compared with different implementations based on Fourier transforms, demonstrating their equivalences and the advantages provided by the former. We demonstrate that the phase error in the presence of grid frequency deviations and the transient length are reduced by half in comparison to the discrete Fourier transform. A novel algorithm is developed to provide frequency adaptation to the DCT, taking advantage of its good features. The window width is adjusted in real time according to the actual value of the grid fundamental frequency by means of a phase-locked loop. A technique based on dithering is employed to overcome the limitation caused by the truncation of the window number of samples, so the frequency resolution is enhanced. The theoretical approach is verified by simulated and experimental results.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제1권3호
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• pp.125-132
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• 2012

마이크로그리드(microgrid)의 독립적 운용방식(islanded operation mode)에서는 전력 공급량과 전력 수요량 사이의 균형을 맞추기 위하여 부하차단(load shedding) 기법이 사용된다. 기존의 부하차단 기법들은 부하의 요구량이 연속적인 값의 범위를 갖는다고 가정하였다. 그러나 일부 부하는 이산적인 정수 값을 사용하여 자신의 요구량을 나타낸다. 따라서 본 논문에서는 독립형 운용방식 환경에서 부하 요구량의 이산적인 특성을 고려한 부하차단 기법을 다중 에이전트 시스템을 이용하여 설계한다. 또한 시스템 구조, 에이전트 기능, 그리고 에이전트 간 통신 프로토콜을 추가로 정의 및 확장함으로써 시스템을 구현하였으며, 구현된 시스템을 기반으로 다양한 시나리오 환경에서의 실험을 통하여 그 성능을 증명하였다.

• 대한교통학회:학술대회논문집
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• 대한교통학회 1998년도 Proceedings The 4th International Transport Symposium
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• pp.160-167
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• 1998

Recent world-wide interest in activity-based travel behavior modeling has generated an entirely new perspective on how the profession views the travel demand process. This paper seeks to further promote the case of activity-based travel behavior models by providing some empirical evidence of relationship between travel time and activity duration decision for worker with transportation panel data. The travel time from home to work and from work to home, without activity involvement, is estimated by the Ordinary Least Squares (OLS) method. And, the travel time to and from the selected activity and the activity duration are modeled simultaneously by the Three Stage Least Squares (3SLS) method due to the endogenous relationship between travel time and activity duration. Two kinds of models, OLS and 3SLS, include selectivity bias corrections in a discrete/continuous framework, because of the inter-relationship between the choice of activity type/travel mode (discrete) and the travel time/activity duration (continuous). Estimation is undertaken using a sample of over 1300 household two-day trip diaries collected from the same travelers in the Seattle area in 1989. The behavioral consequences of these models provide interesting and provocative findings that should be of value to transportation policy formulation and analysis.

• 농촌지도와개발
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• 제24권4호
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• pp.249-264
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• 2017

Modeling the consumer demand of fresh meat requires its distinct feature which other types of food product does not have. Most of the fresh meat products are likely to be unbranded, bought on a weight basis and affected by macro shocks such as seasonality, holiday effect and the disease incidence. Furthermore, consumers tend to purchase multiple categories of fresh meat in a week. Therefore, we apply a multiple discrete/continuous model on fresh meat consumption data to study the effect of macro shocks on fresh meat sales as well as of price change. As a result shows, Each fresh meat is relatively more likely to be bought in peak season of each fresh meat compared with imported pork which is set as a 'reference category' in this analysis. For clarity of the effect of disease incidence, we perform further analysis regarding the effect of livestock disease on fresh meat purchase probability. It shows that the avian flu in 2014 has strong negative impact on the purchase probability of chicken and the foot-and-mouth disease has negative impact on the purchase probability of pork and beef for part of outbreak periods.

• 대한산업공학회지
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• 제37권4호
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• pp.331-341
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• 2011

This paper considers an inbound lot-sizing and outbound dispatching problem for a single product in a thirdparty logistics (3PL) distribution center. Demands are dynamic and finite over the discrete time horizon, and moreover, each demand has a delivery time window which is the time interval with the dates between the earliest and the latest delivery dates All the product amounts must be delivered to the customer in the time window. Ordered products are shipped by multiple vehicle types and the freight cost is proportional to the vehicle-types and the number of vehicles used. First, we formulate a mixed integer programming model. Since it is difficult to solve the model as the size of real problem being very large, we design a conventional genetic algorithm with a local search heuristic (HGA) and an improved genetic algorithm called adaptive genetic algorithm (AGA). AGA spontaneously adjusts crossover and mutation rate depending upon the status of current population. Finally, we conduct some computational experiments to evaluate the performance of AGA with HGA.

• 기술혁신학회지
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• 제14권spc호
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• pp.1256-1284
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• 2011

기존에 신기술제품 소비시장을 연구하기 위한 많은 모델이 있었으나, 소비자, 유통업자, 제조업자로 구성되는 가치사슬 단계의 전반적인 상호작용을 통한 시장의 움직임을 파악하는 연구는 미약하다. 이에 본 논문에서는 수요자, 유통업자, 제조업자로 구성되는 다중행위자와 소비자선택이론의 상호작용을 통해 신기술상품의 구매에 대한 수요확산을 시뮬레이션하였다. 본 연구는 신기술상품 구매 시의 소비자의 선호도를 분석하고자 컨조인트 분석을 적용하여 선호도 계수를 추정하였으며 행위자기반모형을 통해 신기술 채택 및 인센티브 제공 여부에 따른 소비행태를 시뮬레이션 분석하였다. 분석결과 기술제품의 시장점유율은 재고수준에 따른 인센티브의 제공과 신기술제품의 상품적용에 따른 소비자층의 제품수용이 조화롭게 이루어질 때 상승하는 것으로 나타났다.