• 전기학회논문지
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• 제66권1호
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• pp.16-22
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• 2017

In order to reduce costs of electricity energy at periods of peak demand, there has been an exponential interest in Demand Response (DR). This paper discusses the effect on the participants' behavior in response to DR. Under the assumption of perfect competition, the equilibrium point of the electricity market with DR is derived by modeling a DR curve, which is suitable for microeconomic analysis. Cournot model is used to analyze the electricity market of imperfect competition that includes strategic behavior of the generation companies. Strategic behavior with DR makes it harder to compute equilibrium point due to the non-differential function of payoff distribution. This paper presents a solution method for achieving the equilibrium point using the best response function of the strategic players. The effect of DR on the electricity market is illustrated using a test system.

• 문화경제연구
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• 제17권2호
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• pp.3-28
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• 2014

공연예술 수요는 가격 이외의 사회 경제적 요인들 그리고 교육과 경험 지식 같은 문화자본의 영향을 받는다고 알려져 있다. 공연에 대한 지식과 경험과 관련하여 본 연구에서는 개별 공연이 가지는 정보가 수요에 미치는 영향을 거래비용 관점에서 분석하려 하였다. 이를 위해 실제 공연장 자료를 바탕으로 연구 모형을 회귀분석을 이용하여 선택된 공연의 장르, 가격, 인지도 등의 요소가 유료관람객 수에 준 영향을 실증 분석한 결과, 거래비용 특성에 따라 수요가 달라짐을 알 수 있었다. 그리고 일반적으로 가격과 수요는 반비례 관계로 알려져 있으나, 분석 결과 일정 가격 이상에서는 정비례 관계로 나타났다. 이 결과를 해석해보면, 가격이 상품의 질을 평가하는 정보로 사용된 것으로 볼 수 있으며, 관객이 공연관람을 통하여 얻을 수 있는 기대효용에 가격이 영향을 미치는 것을 의미한다. 상기한 분석결과를 통하여 공연의 가격에 따른 소비자의 거래비용의 경향을 확인할 수 있었다. 또한 분석 결과가 순수한 공연 관람 이외의 사회적 맥락의 소비라는 이론을 뒷받침할 수 있는 가능성을 보여주었다.

• 한국지진공학회논문집
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• 제27권5호
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• pp.213-220
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• 2023

Seismic fragility curves play a crucial role in assessing potential seismic losses and predicting structural damage caused by earthquakes. This study compares non-sampling-based methods of seismic fragility curve derivation, particularly the probabilistic seismic demand model (PSDM) and finite element reliability analysis (FERA), both of which require employing sophisticated finite element analysis to evaluate and predict structural damage caused by earthquakes. In this study, a three-dimensional finite element model of API 5L X65, a buried gas pipeline widely used in Korea, is constructed to derive seismic fragility curves. Its seismic vulnerability is assessed using nonlinear time-history analysis. PSDM and a FERA are employed to derive seismic fragility curves for comparison purposes, and the results are verified through a comparison with those from the Monte Carlo Simulation (MCS). It is observed that the fragility curves obtained from PSDM are relatively conservative, which is attributed to the assumption introduced to consider the uncertainty factors. In addition, this study provides a comprehensive comparison of seismic fragility curve derivation methods based on sophisticated finite element analysis, which may contribute to developing more accurate and efficient seismic fragility analysis.

• 자원ㆍ환경경제연구
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• 제31권3호
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• pp.319-342
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• 2022

본 연구는 2019년 부산광역시 일부 자치구의 종량제봉투 가격 인하 사례를 이용하여 자연실험 합성집단통제 이중차분법을 통해 종량제봉투 가격이 생활폐기물 배출량에 미치는 영향을 분석했다. 수요 및 가격탄력도를 추정할 때 흔히 발생할 수 있는 내생성 문제를 고려하기 위해 가격 동결 자치구를 합성통제집단으로, 가격 인하 자치구를 처치집단으로 설정하여 분석했다. 분석 결과, 수요의 가격탄력도는 0.05~0.11 수준으로 종량제봉투 가격은 판매량에 거의 영향을 미치지 못했다. 종량제봉투는 필수재적 성격이 강하고 가구 소득에서 차지하는 비중이 매우 작기 때문으로 보인다. 이는 종량제봉투의 수요곡선이 거의 수직에 가까우므로 폐기물 감소 목표 달성을 위해서는 가격정책 보다 수요곡선 자체를 이동시킬 수 있는 정책이 더욱 효과적일 수 있음을 시사한다.

• Computers and Concrete
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• 제10권1호
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• pp.35-47
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• 2012

The ideal gradating curve is used in this study to estimate densified aggregate blended ratio and total surface area of aggregate, there by under assigned paste amount of concrete, and coating paste thickness can then be deduced. Four groups of concrete mixtures were prepared and the corresponding concrete properties, such as workability, compression strength, ultrasonic velocity, surface resistivity and chloride ion penetration, were measured and finally the results are interpreted in terms of "coating thickness". The result shows as the coating thickness of the concrete is higher than critical one, the coating thickness on aggregate does affect the workability, and whatever workability is required the superplasticizer can be adjusted to achieve the demand workability. Under a fixed paste quality at the same age, coating paste thickness is inversely proportional to the concrete properties, especially as the coating thickness gets thinner.

• 산업경영시스템학회지
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• 제43권4호
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• pp.93-106
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• 2020

This research explores how imported automobile companies can develop their strategies to improve the outcome of their recalls. For this, the researchers analyzed patterns of recall demand, classified recall types based on the demand patterns and examined response strategies, considering plans on how to procure parts and induce customers to visit workshops, recall execution capacity and costs. As a result, recalls are classified into four types: U-type, reverse U-type, L- type and reverse L-type. Also, as determinants of the types, the following factors are further categorized into four types and 12 sub-types of recalls: the height of maximum demand, which indicates the volatility of recall demand; the number of peaks, which are the patterns of demand variations; and the tail length of the demand curve, which indicates the speed of recalls. The classification resulted in the following: L-type, or customer-driven recall, is the most common type of recalls, taking up 25 out of the total 36 cases, followed by five U-type, four reverse L-type, and two reverse U-type cases. Prior studies show that the types of recalls are determined by factors influencing recall execution rates: severity, the number of cars to be recalled, recall execution rate, government policies, time since model launch, and recall costs, etc. As a component demand forecast model for automobile recalls, this study estimated the ARIMA model. ARIMA models were shown in three models: ARIMA (1,0,0), ARIMA (0,0,1) and ARIMA (0,0,0). These all three ARIMA models appear to be significant for all recall patterns, indicating that the ARIMA model is very valid as a predictive model for car recall patterns. Based on the classification of recall types, we drew some strategic implications for recall response according to types of recalls. The conclusion section of this research suggests the implications for several aspects: how to improve the recall outcome (execution rate), customer satisfaction, brand image, recall costs, and response to the regulatory authority.

• 산업공학
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• 제22권4호
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• pp.368-375
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• 2009

This paper considers a two-stage supply system consisting of two make-to-stock facilities. The facility in the first stage produces a single type of component in anticipation of future demands from the market and the end item production while the facility in the second stage produces the end item in anticipation of future demands from the OEM customers. The facility in the first stage has the option of to accept or reject each incoming demand from the market. In this paper, we address the problem of how to control the exogenous component demand and how to manage the production of the end item and the component so as to maximize the system's profit subject to the system costs. In this paper, we present a heuristic policy that is the base-stock production policy combined with a linear switching curve for component demand control. Numerical study is implemented under different operating conditions of the system and it shows that the performance of the heuristic is very promising compared to that of the optimal policy for the Markov model.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.561-565
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• 2006

The paper presents a method of assessing the adequate tapaclty of photovoltaic generation systems for public buildings based on analysis of load variation patterns of customers. When PV systems are installed for supplying power for the customer load, reverse power relay is required by the guideline to be installed at the point of common coupling with the power network. The suggested method analyzes daily, weekly and monthly load demand of the customer that Irishes PV system installation, and determines the appropriate rating of the PV system for preventing PV generation from exceeding the customer demand. This work is expected to support renewable energy dissemination projects of public organizations.

• 대한교통학회:학술대회논문집
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• 대한교통학회 2000년도 제37회 학술발표회논문집
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• pp.89-115
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• 2000

Traffic signal setting policies and traffic assignment procedures are mutually dependent. The combined signal control and traffic assignment problem deals with this interaction. With the total travel time minimization objective, gradient based local search methods are implemented. Deterministic user equilibrium is the selected user route choice rule, Webster's delay curve is the link performance function, and green time per cycle ratios are decision variables. Three implemented solution codes resulting in six variations include intersections operating under multiphase operation with overlapping traffic movements. For reference, the iterative approach is also coded and all codes are tested in four example networks at five demand levels. The results show the numerical gradient estimation procedure performs best although the simplified local searches show reducing the large network computational burden. Demand level as well as network size affects the relative performance of the local and iterative approaches. As demand level becomes higher, (1) in the small network, the local search tends to outperform the iterative search and (2) in the large network, vice versa.

• Structural Engineering and Mechanics
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• 제88권4호
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• pp.323-334
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• 2023

The submerged floating tunnel (SFT) infrastructure has been regarded as an emerging technology that efficiently and safely connects land and islands. The SFT route problem is an essential part of the SFT planning and design phase, with significant impacts on the surrounding environment. This study aims to develop an optimization model considering transportation and structure factors. The SFT routing problem was optimized based on two objective functions, i.e., minimizing total travel time and cumulative strains, using NSGA-II. The proposed model was applied to the section from Mokpo to Jeju Island using road network and wave observation data. As a result of the proposed model, a Pareto optimum curve was obtained, showing a negative correlation between the total travel time and cumulative strain. Based on the inflection points on the Pareto optimum curve, four optimal SFT routes were selected and compared to identify the pros and cons. The travel time savings of the four selected alternatives were estimated to range from 9.9% to 10.5% compared to the non-implemented scenario. In terms of demand, there was a substantial shift in the number of travel and freight trips from airways to railways and roadways. Cumulative strain, calculated based on SFT distance, support structure, and wave energy, was found to be low when the route passed through small islands. The proposed model helps decision-making in the planning and design phases of SFT projects, ultimately contributing to the progress of a safe, efficient, and sustainable SFT infrastructure.