• Title, Summary, Keyword: capacity

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A Capacity Expansion Planning Model for Single-Facility with Two Distinct Capacity Type (두개의 차별적인 용량형태를 갖는 단일설비에 대한 용량 확장계획 모형)

  • Chang, Suk-Hwa
    • Journal of Korean Institute of Industrial Engineers
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    • v.16 no.1
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    • pp.51-58
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    • 1990
  • A deterministic capacity expansion planning model for a two-capacity type facility is analyzed to determine the sizes to be expanded in each period so as to supply the known demands for two distinct capacity type(product) on time and to minimize the total cost incurred over a finite planning horizon of T periods. The model assumes that capacity unit of the facility simultaneously serves a prespecified number of demand units of each capacity type, that capacity type 1 can be used to supply demands for capacity type 2, but that capacity type 2 can't be used to supply demands for capacity type 1. Capacity expansion and excess capacity holding cost functions considered are nondecreasing and concave. The structure of an optimal solution is characterized and then used in developing an efficient dynamic programming algorithm that finds optimal capacity planning policy.

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Rental Resource Management Model with Capacity Expansion and Return (용량 확장과 반납을 갖는 렌탈 자원 관리모델)

  • Kim Eun-Gab;Byun Jin-Ho
    • Journal of the Korean Operations Research and Management Science Society
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    • v.31 no.3
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    • pp.81-96
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    • 2006
  • We consider a rental company that dynamically manages Its capacity level through capacity addition and return While serving customer with its own capacity, the company expands its capacity by renting items from an outside source so that it can avoid lost opportunities of rental which occur when stock is not sufficient. If stock becomes sufficiently large enough to cope with demands, the company returns expanded capacity to the outside source. Formulating the model into a Markov decision problem, we identify an optimal capacity management Policy which states when the company should expand its capacity and when it should return expanded capacity after capacity addition. Since it is intractable to analytically find the optimal capacity management policy and the optimal size of capacity expansion, we present a numerical procedure that finds these optimal values based on the value iteration method. Numerical analysis is implemented and we observe monotonic properties of the optimal performance measures by system parameters, which are meaningful in developing effective heuristic policies.

Evaluation of flood control capacity of agricultural reservoirs during flood season (홍수기 농업용 저수지의 홍수조절용량의 평가)

  • Jang, Ik Geun;Lee, Jae Yong;Lee, Jeong Beom;Kim, Jin Soo
    • Journal of The Korean Society of Agricultural Engineers
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    • v.56 no.4
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    • pp.69-75
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    • 2014
  • We investigated flood control capacity of 484 agricultural reservoirs with storage capacity of over 1 million $m^3$ in South Korea. In general, agricultural reservoir secures flood control capacity by setting up limited water level during flood season from late June to mid-September. The flood control capacity of an agricultural reservoir during flood season can be divided into stable flood control capacity during non-flood season, stable flood control capacity associated with limited water level, and unstable flood control capacity associated with limited water level. In general, the flood control capacity significantly (P < 0.001) increased with reservoir capacity irrespective of type of spillway. The unstable flood control capacity accounted for about 20 % of reservoir capacity in the uncontrolled reservoirs. The study reservoirs showed flood control capacity of 0.60-65 billion (B) $m^3$ and stable flood control capacity of 0.43-47 B $m^3$, depending on the upper and lower limited water levels during the flood season. The stable flood control capacity of the gated reservoirs (0.29-0.33 B $m^3$) was about two times than that of reservoirs with uncontrolled spillways (0.14 B $m^3$). The ratios of stable flood control capacity to reservoir capacity for agricultural reservoirs range from 21 to 23 %, similar to that for Daecheong multipurpose dam. Moreover, the reservoirs with over 100 mm ratio of flood control capacity to watershed area accounted for 38 % of total gated reservoirs. The results indicate that many agricultural reservoirs may contribute to controlling flood in the small watersheds during the flood season.

Comparing Empirical Methods of Highway Capacity Estimation (실험적 용량산정 방법 비교 연구)

  • Moon, Jaepil;Cho, Won Bum
    • International Journal of Highway Engineering
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    • v.16 no.1
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    • pp.57-62
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    • 2014
  • PURPOSES : Capacity is a main factor of determining the number of lane in highway design or the level of service in road on operation. Previous studies showed that breakdown may occur before capacity is reached, and then it was concluded that capacity is a stochastic value rather than a deterministic one. In general, estimating capacity is based on average over maximum traffic volume observed for capacity state. This method includes the empirical distribution method(EDM) and would underestimate capacity. This study estimated existing empirical methods of estimating stochastic highway capacity. Among the studied methods are the product limit method(PLM) and the selected method(SM). METHODS : Speed and volume data were collected at three freeway bottleneck sites in Cheonan-Nonsan and West Sea Freeway. The data were grouped into a free-flow state or capacity state with speeds observed in the bottlenecks and the upstream. The data were applied to the empirical methods. RESULTS : The results show that the PLM and SM estimated capacity higher than EDM. The reason is that while the EDM is based on capacity observations only, the PLM and SM are based on free-flow high volumes and capacity observations. CONCLUSIONS : The PLM and SM using both free-flow and capacity observations would be improved to enhance the reliability of the capacity estimation.

Suppression of Strategic Capacity Withholding by Capacity Payment in a Competitive Generation Market (경쟁적 전력시장에서 용량요금에 의한 전략적 용량철회 억제)

  • Lee, Kwang-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.7
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    • pp.1199-1204
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    • 2007
  • In a cost based pool market, the generation capacity can be used as strategic bids by generation companies (Gencos) with the cost functions open to the market. Competition using strategic capacities is modeled by Cournot and Perfect Competiton (PC) model, and transformed into two by two payoff matrix game with Gencos' decision variables of Cournot and PC model. The payoff matrices vary when capacity payments are given to Gencos in accordance with their capacity bids. Nash Equilibrium (NE) in the matrices also moves with capacity price changes. In order to maximize social welfare of the market, NE should locate in a certain position of the payoff matrices, which corresponds to a PC NE. A concept of a critical capacity price is proposed and calculated in this paper that is defined as a minimum capacity price leading to PC NE. The critical capacity price is verified to work as a tool for suppressing a strategic capacity withholding in simulations of a test system.

Relative Capacity of the Spectrum-Overlapped DS-CDMA System using the Lanczos Chip Waveform

  • Lee, Dong-Hun;Ryu, Heung-Gyoon
    • Journal of electromagnetic engineering and science
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    • v.2 no.1
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    • pp.1-4
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    • 2002
  • Performance improvement of the DS-CDMA system by the spectrum-overlap is important for better service quality or more system capacity. In this paper, an analysis thor capacity improvement is newly considered when the Lanczos chip waveform is used for the spectrum-overlapped DS-CDMA system. RC(relative capacity) is the ratio of the capacity of overlapping system to that of non-overlapping system, which is used for the expression of the capacity improvement. The optimal overlapping ratio is numerically found to make the maximum capacity improvement When the rectangular chip waveform is used far the overlapping system, maximum capacity improvement is increased by about 10% at the required BER=$10^{-3}$TEX> and the optimal overlapping ratio is 1.23. When the 95 % power bandwidth is considered for the Lanczos chip waveform, maximum capacity improvement is increased by 34.4% at overlapping ratio of 1.55 when the required BER is $10^{-3}$TEX>. The lower required BER far the better communication quality makes gradually smaller capacity improvement.

Dynamic Effects of Capacity Mechanisms of Electricity Market on the Market Performances (전력시장의 용량 메커니즘이 전력시장 성과에 미치는 동태적 효과)

  • Jang, Dae-Chul;Park, Kyung-Bae
    • Korean System Dynamics Review
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    • v.12 no.4
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    • pp.93-124
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    • 2011
  • The introduction of competition in the generation of electricity has raised the fundamental question of whether markets provide the right incentives for the provision of the capacity needed to maintain system reliability. Capacity mechanisms are adopted around the world to guarantee appropriate level of investment in electricity generation capacity. In this study, we discuss these approaches and analyze the capacity pricing mechanisms from the adequacy perspective. We conclude that the design of capacity mechanism is very important to decrease electricity spot price and increase total electric capacity. Specifically, the constant of capacity pricing mechanism made a difference to the performance of electricity market. However, the slope of capacity price mechanism is better than the constant of that in improving performance of electricity market.

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The Accumulation of Rural Village Capacity - Focusing on the Support Structure of the Capacity Phase - (농촌 마을 역량의 축적 - 역량단계별 지원 체계를 중심으로 -)

  • Kim, Doo-Soon
    • Journal of Agricultural Extension & Community Development
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    • v.23 no.4
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    • pp.431-439
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    • 2016
  • There are rural development policy for creating liveable rural. The support structure of the capacity phase of the Master Plan of Comprehensive Rural Village Development Project would that one. The support structure of the capacity phase has implied the assumption that the accumulated capacity of the village to the previous step will have a significant impact on the business to the next level. Rural development should be understood that simple: rather than for business applications, processes community is going to build capacity through continuous learning and practice. Its accumulated capacity should be possible to predict and then steps must be developed continuously for a long time, looking at the previous phase. Thus, according to the support structure of the capacity phase, it should be applied a causal relationship between the front and rear phase.

The Impact of Capacity Flexibility in a Rental Operation on the Financial Performance (렌탈 운영에서 용량 유연성 확보가 기업의 수익성에 미치는 영향)

  • Kim, Eungab
    • Journal of the Korean Operations Research and Management Science Society
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    • v.39 no.4
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    • pp.153-165
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    • 2014
  • We present a new framework for rental capacity management in which rental capacity is dynamically managed by means of temporary inventory addition/return. While serving customers with its own (native) capacity, the rental firm rents additional rental capacity from an upper echelon rental company so that it can avoid lost sales which may occur when stock is not sufficient, and returns it when stock becomes sufficiently large enough to cope with demands. Formulating the model as a Markov decision process, we investigate a flexible capacity addition/return policy that maximizes the firm's profit with respect to system costs. Numerical study indicates that rental operation with capacity addition/return can be economically favorable over rental operation without capacity expansion/return and can contribute the reduction in the size of native rental capacity.