• 조명전기설비학회논문지
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• 제23권2호
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• pp.182-189
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• 2009

경쟁적 전력시장에서 발전회사의 전략적 행위를 분석하기 위해서 일반적으로 내쉬균형(Nash equilibrium) 이론이 널리 사용되고 있다. 기존 연구에 의하면 송전제약이 있는 전력시장에서는 최적반응의 불연속으로 인해 순수전략내 쉬균형이 존재하지 않게 되고, 이때는 혼합전략 내쉬균형이 전력시장의 균형이 된다. 본 논문에서는 송전제약이 있는 2-지역 전력시장에서 혼합전략 내쉬균형을 유도하고, 송전용량이 혼합전략 내쉬균형에 미치는 영향을 해석하였다.

• 산업공학
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• 제13권1호
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• pp.110-119
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• 2000

Resource-constrained project scheduling is to allocate limited resources to activities to optimize certain objective functions and to determine a start time for each activity in the project such that precedence constraints and resource requirements are satisfied. This study suggests a multi-project scheduling model which can level work loads, make the most of production capacity and restrain the delay of delivery by developing a heuristic algorithm which minimizes the project completion time and maximizes the load rate under resource constraints.

• 산업공학
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• 제14권4호
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• pp.334-340
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• 2001

The theory of constraints (TOC) has become a valuable system in modern operations management. Using the ideas and methods of the TOC, companies can achieve a large reduction of work-in-process and finished-goods inventories, significant improvement in scheduling performance, and substantial earnings increase. The purpose of this paper is to calculate the optimal size of the time buffer which is used to accommodate disruptions in production processes and provide maximum productivity of capacity constrained resources. After the problem formulation in terms of single server queueing model, we observed the system behavior by sensitivity analyses.

• 경영과학
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• 제10권1호
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• pp.207-216
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• 1993

The purpose of this paper is to develop a branch and bound algorithm for the transportation problem with a limited number of company owned vehicles. First, we find an initial solution by solving quasi-assignment subproblem induced by relaxing constraints of the vehicle capacity and illegal tours elimination equations. Second, we build routing from the assignment, and if there is a routings which violates relaxed constraints, we introduce branches of the subproblem in order to remove it. After all branches are searched, we get the optimal solution.

• 대한전기학회논문지
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• 제33권6호
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• pp.241-246
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• 1984

The power system scheduling process is formulated as an optimization problem with linear inequality constraints. AC Loadflow method is used for the problem solution and line losses are considered. The constraints under consiceration are generator power limits, load schedding limits and line capacity limits. In solving the objective function the Dual Relaxation method is adopted. Tests indicate that the method is practical for real time applications.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1993년도 춘계공동학술대회 발표논문 및 초록집; 계명대학교, 대구; 30 Apr.-1 May 1993
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• pp.353-353
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• 1993

• Journal of Communications and Networks
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• 제13권5호
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• pp.472-480
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• 2011

In this paper, we investigate two new candidate transmission schemes, non-orthogonal frequency reuse (NOFR) and beam-hopping (BH). They operate in different domains (frequency and time/space, respectively), and we want to know which domain shows overall best performance. We propose a novel formulation of the signal-to-interference plus noise ratio (SINR) which allows us to prove the frequency/time duality of these schemes. Further, we propose two novel capacity optimization approaches assuming per-beam SINR constraints in order to use the satellite resources (e.g., power and bandwidth) more efficiently. Moreover, we develop a general methodology to include technological constraints due to realistic implementations, and obtain the main factors that prevent the two technologies dual of each other in practice, and formulate the technological gap between them. The Shannon capacity (upper bound) and current state-of-the-art coding and modulations are analyzed in order to quantify the gap and to evaluate the performance of the two candidate schemes. Simulation results show significant improvements in terms of power gain, spectral efficiency and traffic matching ratio when comparing with conventional systems, which are designed based on uniform bandwidth and power allocation. The results also show that BH system turns out to show a less complex design and performs better than NOFR system specially for non-real time services.

• 한국IT서비스학회지
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• 제10권3호
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• pp.49-59
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• 2011

A ship scheduling model is presented for the raw material transportation problem with yard storage constraints in a steel mill. The problem is formulated as 0, 1 mixed integer programming considering such constraints as loading port conditions, ship size and hold capacity, unloading conditions, and yard storage space. In addition, inventory related constraints including safety stock are taken into consideration to support the continuous operations of steel making process. The proposed model has been implemented and applied successfully to a real world problem, and its results show the improvement of performance compared to the traditional method. For example, the arrival dates of ships are determined satisfying the constraints. The total inventory level is minimized at the stock yard as a result. Also, the safety inventory level is always kept at the planning stage, and the standard deviation of total inventory level is reduced significantly. Further research is expected to develop efficient heuristics to have a better response time for even larger scale problems.

• 대한지역사회영양학회지
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• 제26권6호
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• pp.455-466
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• 2021

Objectives: The purpose of this study was to investigate the effects of internal and external capacity on the practical capacity for food waste disposal in adults. Methods: The study subjects were 410 adults who answered a structured questionnaire. The survey was conducted in January 2021. Data were analyzed through descriprive analysis, t-test, ANOVA, and multiple regression analysis using the SPSS Win 24.0. Results: First, in the analysis of internal capacity, attitude (3.95 out of 5 points) scored higher than knowledge (3.59 points). Attitudes showed significant differences according to gender (P < 0.001), age (P < 0.001), and income (P < 0.001). Knowledge showed significant differences according to gender (P < 0.01) and age (P < 0.05). Second, in the analysis of capacity, market constraints (3.73 points) scored the highest, followed by institutional conditions (3.48 points) and reference group (3.36 points). Market constraints differed according to gender (P < 0.001), and institutional conditions differed according to income (P < 0.001). There was a significant difference in the reference group according to the level of education (P < 0.05) and income (P < 0.05). Third, the practical capacity scores appeared in the order of separating discharge behavior, using behavior, purchasing behavior, and leadership behavior. Separating discharge behavior showed significant differences according to gender (P < 0.001), education level (P < 0.05), and income (P < 0.01). Using behavior showed a difference according to gender (P < 0.01), and purchasing behavior showed a significant difference according to income (P < 0.05). Leadership behavior showed no difference according to demographic factors. Fourth, internal capacity and external capacity showed a significant positive relationship with practical capacity. Factors affecting purchasing behavior were knowledge, attitude, institutional conditions, and reference group, and their explanatory power was 53%. Factors influencing using behavior were knowledge, attitude, institutional conditions, and reference group, and had an explanatory power of 37%. Leadership behavior was influenced by institutional conditions and the reference group, with an explanatory power of 31%. Conclusions: Internal capacity, external capacity, and practical capacity show differences according to demographic factors. Factors influencing the practical capacity of adults were knowledge, attitude, institutional conditions, and reference group.

• Journal of Electrical Engineering and Technology
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• 제2권4호
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• pp.494-499
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• 2007

In this paper, we have investigated how transmission network constraints can be modeled in an electricity market equilibrium model. Under Cournot competition assumption, a game model is set up considering transmission line capacity constraints. Based on locational marginal pricing principle, market clearing is formulated as a total consumers# benefit maximization problem, and then converted to a conventional optimal power flow (OPF) formulation with a linearized transmission model. Using market clearing formulation, best response analysis is formulated and, finally, Nash equilibrium is formulated. In order for illustration, a numerical study for a four node system with two generating firms and two loads are presented.