• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.347-349
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• 2000

Under an open transmission access, the generation dispatch is determined by the bidding process of market participants. Congestion occurs when the dispatch would result in the violation of operational constraints. Congestion problem is formulated and solved by OPF(optimal power flow) calculation. The objective functions in OPF are given as quadratic cost functions or piecewise linear functions of bidding functions. In this study, the optimization technique of generation dispatch is presented for the combination of two types of quadratic and linear cost functions.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.1060-1063
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• 2005

Growing qualitative and cost-based competition with the roads and air modes will be oblige the railways to make better use of their existing infrastructure than present. Development and use of new signalling and safety systems and introduction of wide-area control systems may make it possible to operate railway efficiently. Therefore. a comprehensive series of measures must be developed in the fields of technology, planning and management, measures which can operate today's korean railway systems intelligently and achieve cost savings, better quality services and improved results.

• Knowledge Management Research
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• v.10 no.3
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• pp.35-49
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• 2009

The purpose of this study is to examine whether suppliers are able to benefit by means of constructing a relationship-specific intangible asset and participating in collaboration with purchasers to actively maintain value created while mutually using inter-organizational information systems. To achieve the purpose of this study. 82 questionnaires have been analyzed from suppliers which are using electronic transactions through inter-organizational information systems. As a result, business process specificity and domain knowledge specificity, which are relationship-specific intangible assets, affect operational collaboration and strategic collaboration, which are classified by level of decision-making. Although both types of collaboration are needed to achieve both strategic and operational benefits, we find each collaboration to be uniquely promoted by a specific types of relationship-specific intangible asset. Operational collaboration is found to be an antecedent to operational benefit and strategic collaboration is found to be an antecedent to strategic benefits. No crossover between collaboration and supplier's benefits is found. Consequently, the result of this study shows collaboration is needed for domestic suppliers, which have relatively low levels of collaboration, to keep maintain relationship-specific intangible assets and to prevent the relationship termination cost when transactions have been stopped between supplier and purchaser. Also the results imply the supplier can have advantages by participating in collaboration.

• Journal of the Korean Institute of Navigation
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• v.22 no.4
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• pp.1-14
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• 1998

There are three basic modes of operation of ships: liner, tramp and industrial operations. Industrial operations, where the owner of the cargo, i.e. the industrial carrier controls the ships, abound in the shipment of bulk commodities, such as oil, chemicals and ores. Industrial carriers strive to minimize the shipping cost of their cargoes. This paper is concerned with the operational optimization problem of a fleet owned by major international oil company. The major oil company is a holding corporation for a group of oil producing, transporting, refining, and marketing companies located in various countries throughout the world. The operational optimization problem of the fleet is divided into two-phases. The front end corresponds to the optimization of transporting crude oil, product mix, and the distribution of product oil to meet market demand. The back end tackles the operational optimization problem of the fleet to meet the transportation demand derived from the front end. A case study is carried out with the H major oil company problem composed by reflecting the practices of an international major oil company. The results are summarized and examined in the point of optimization for the total operation of the H major oil company and the operational optimization problem of the fleet. The paper concludes with the remark that the results of the study might be useful and applicable in practices of these related decision problems.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.576-582
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• 2013

Typical highway infrastructure systems include roadway pavement, drainage systems, tunneling, and other hardware components such as guardrails, traffic signs, and lighting. Tunnels in a highway system have provided significant advantages to overcoming various natural challenges including crossing underneath bodies of water or through mountainous areas. While only a few tunnel failure cases have been reported, the failure rate is likely to increase as these assets age and because agencies have not emphasized tunneling asset management. A tunnel system undergoes a deterioration life cycle pattern that is similar to other infrastructure systems. There are very few agencies in the United States implementing comprehensive tunnel asset management programs. While current tunnel asset management programs focus on inspection, maintenance, and operation safety, there is an increasing need for the development of a comprehensive life cycle tunnel asset management program. This paper describes a conceptual framework for a comprehensive tunnel asset management program. The framework consists of three basic phases including a strategic plan, a tactical plan, and an operational plan to provide better information to the decision makers. The strategic plan is a basic long term approach of tunnel asset management. The tactical plan determines specific objectives and the operational plan actually applies asset management objectives in practice. The information includes operational condition, structural condition, efficiency of the system, emergency response, and life cycle cost analysis for tunnel capital improvement project planning.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.2
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• pp.113-127
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• 2007

In this study, a model to calculate the expected total construction cost is developed that simultaneously considers the rehabilitation cost related to the sliding of the caisson, the economic damage cost due to harbor shutdown in the event of excessive caisson sliding, and the economic damage cost due to temporal operational stoppage by excessive wave overtopping. A discount rate is used to convert the damage costs occurred at different times to the present value. The optimal cross-section of a caisson is defined as the cross-section that requires a minimum expected total construction cost within the allowable limit for the expected sliding distance of the caisson during the lifetime of the breakwater. Two values are used for the allowable limit: 0.3 and 0.1 m. It was found that the economic damage cost due to harbor shutdown by excessive caisson sliding is more critical than the rehabilitation cost of the caisson or the economic damage cost by excessive wave overtopping in the decision of the optimal cross-section. In addition, the optimal cross-section of the caisson was shown to be determined by the allowable limit for the expected sliding distance rather than the minimum expected total construction cost as a larger value is used for the threshold sliding distance of the caisson for harbor shutdown.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.451-456
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• 2013

Development of the technologies for offshore wind power is proceeding actively and the installation capacity is continuously increasing because of its many advantages in comparison with the land wind power. Accordingly, project for Southwestern 2.5GW offshore wind power plant is in progress in Korea. Design of electric power systems for offshore wind power plant is very important due to its high investment and operational costs. Hence, it needs to be designed in order to minimize costs. This way can be employed in determining the installation location of offshore substation for HVAC wind power plant. According to the offshore substation site, MV inter-array cable and HV export cable lengths vary and they change a total cost regarding submarine cable. This paper represents cost models with variables which are MV inter-array cable and HV export cable lengths to locate the offshore substation for HVAC wind power plant. It is classified into submarine cable installation cost, reactive power compensator installation cost, ohmic losses, and unsupplied energy cost. By minimizing a total cost, an appropriate installation site of the offshore substation is determined.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1249-1259
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• 2012

This paper proposes a Web Based Online Outage Cost Assessment and Information System(WOOCAIS) for power system outage cost assessment. The proposed WOOCAIS is a kind of web based survey method for outage cost assessment. While conventional survey methods have done outage cost assessment based on survey paper lists collected by post mail or visiting customers, the proposed WOOCAIS is a web based online survey operation and assessment system. Therefore, it can curtail expenditure for survey and also is more convenient than conventional method. It will be set up for actual outage cost assessment system of KEPCO in South Korea in the near future. The WOOCAIS will be applied in various research and actual planning and operation areas. First of all, the assessed results may be not only applied as one of objective function for generation system and grid expansion but also operational planning problems in power system.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.479-487
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• 2013

State Highway Agencies (SHAs) have started utilizing cost-plus-time bidding (A+B bidding) since Federal Highway Agency (FHWA) declared it operational on May 4, 1995. Although this technique has successfully accelerated many projects by incorporating construction time in the bidding competition, a framework to illustrate the interactions of incentive/disincentive (I/D) rates on the competitiveness of contractors participating in the bid competition is yet to be developed. In a previous research, authors indicated that for each bid competition there is an efficient cap for I/D rates which are dictated by the capabilities of contractors in project acceleration. However, the results of previous study were based on the assumption that there is a statistically significant relationship between cost and time. In this study, the entire cost-plus-time projects implemented by the Oklahoma Department of Transportation (ODOT) were investigated. Then the significance of relationship between cost and time were analyzed for each contractor utilizing Analysis of Variance (ANOVA) technique, and the price-time function of each contractor was determined by regression analysis. The results of the analysis indicate that there is a significant relationship between cost and time for the majority of contractors. However, a quadratic relationship is not always significant and for some contractors a linear price-time relationship is significant. The results of this project can be used not only by ODOT to optimize the incentive/disincentive rates but also by contractors to determine the most competitive strategies of other bid participants.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.168-169
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• 2007

Organic transistors are promising in the future development of active devices for flexible, low-cost and large-area photoelectric devices. However, conventional organic field-effect transistors have lowspeed, low-power, and relatively high operational voltage. Vertical type transistors show high-speed and high-current characteristics and are suitable for driver elements of flexible displays.