• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.421-429
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• 2005

Traditionally, determination of the optimal containership size is the most important factor for competitiveness of shipping companies in the shipping market. Under this environment, many shipping companies and researchers have studied about it. The objective of this research is to determine the optimal containership size using a total shipping cost in the main trunk lines. Total shipping cost is calculated at the ground of capital costs, vessel operation costs, voyage costs, port charges and miscellaneous costs for 'Europe-Far East', 'Far East-North America' and 'Europe-Far East-North America' services. Analysis results showed that the 6,500TEU containership is an optimal size on the 'Europe-Far East' and 'Europe-Far East-North America' services. And the 8,200TEU containership is an optimal size on the 'Far East-North America' service. Moreover, if the larger containerships over 8,200TEU class start operation afterward, it would be less competitive in the analyzed 3services.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.4
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• pp.557-566
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• 2002

This paper presents an optimum deck and girder system design for minimizing the life-cycle cost(LCC) of steel box girder bridges. The problem of optimum LCC design of steel box girder bridges is formulated as that of minimization of the expected total LCC that consists of initial cost, maintenance cost and expected retrofit costs for strength, deflection and crack. To demonstrate the cost effectiveness of LCC design of steel box girder bridges, the LCC optimum design is compared with conventional design method for steel box girder bridges. From the numerical investigations, it may be positively stated that the optimum design of steel box girder bridges based on LCC will lead to mote rational, economical and safer design.

• Journal of Korean Society of Steel Construction
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• v.15 no.4 s.65
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• pp.341-358
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• 2003

This paper proposed a general formulation of Life-Cycle Cost (LCC) models and LCC effective design system models of steel bridges suitable for practical implementation. An LCC model for the optimum design of steel bridges included initial cost and direct/indirect rehabilitation costs of a steel bridge as well as repair/replacement costs, loss of contents or fatality and injury losses, road user costs, and indirect socioeconomic losses. The new road user cost model and regional socioeconomic losses model were especially considered because of the traffic network. Illustrative design examples of an actual steel box girder and an orthotropic steel deck bridge were discussed to demonstrate the LCC effectiveness of the design of steel bridges. Based on the results of the numerical investigation, the LCC-effective optimum design of steel bridges based on the proposed LCC model was found to lead to a more rational, economical, and safer design compared with the initial cost-optimum design and the conventional code-based design.

• Journal of Energy Engineering
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• v.8 no.1
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• pp.166-173
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• 1999

본 연구는 램지가격결정방식과 효율적요소가격결정방식을 이용하여 향후 국내 가스산업의 배관망공동이용시 발전용 천연가스의 가격 및 이용료 수준을 파악할 수 있는 천연가스 가격 결정의 이론적 모형을 도출하였다. 또한 사례분석을 통하여 램지가격결정방식(RCPR)과 효율적요소가격결정방식(ECPR)하에서 도출된 최적 가격 및 최적 이용료를 비교·분석하였고 결정변수들이 가격과 이용료에 미치는 영향에 대해서 분석하였다. 그 결과 RCPR에 의한 최적 이용료는 쿠르노 불완전 경쟁하에서 한계직접비용 보다 낮게 도출된데 반해서 ECPR에서는 한계직접비용보다 높게 도출됨으로써 가격결정방식에 따라 최적 이용료의 수준이 상이함을 보였다. 또한 도시가스용 및 발전용 가격은 RCPR 하에서 신규사업자 수가 증가할수록 하락하였고 이용료는 증가하여 한계비용에 접근하였다. 한편 최적 발전용 가격과 최적 이용료는 한계직접비용이 클수록 증가되었고, 역가격탄력성이 클수록 최적 발전용 가격은 증가하는 반면에 최적 이용료는 감소하였다.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.183-193
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• 2007

Traditionally, a congestion charge based on first-best congestion pricing theory, namely, the theory of marginal cost pricing theory, is equal to the difference between marginal social cost and marginal private cost. It is charged on each link so as to derive a user equilibrium flow pattern to a system optimal one. Based on this theory this paper investigates on the characteristics of first-best congestion pricing of multiple user class on road with variable demand, and presents two methods for analysis of social and spatial equity. For these purposes, we study on the characteristics of first-best congestion pricing derived from system optimal in time and in monetary unit, and analyze equity from this congestion pricing with an example network.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.2 s.42
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• pp.17-27
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• 2005

This paper presents an integrated optimum design and a cost effectiveness evaluation method of a viscoelastically damped structural system. The criterion selected for the optimization is the minimization of the life?cycle cost which is a function of structural sizing variables and the amount of the viscoelastic damper. A genetic algorithm is used as a numerical searching technique in order to simultaneously find the optimum parameters of the integrated system. Optimal distributions of design variables according to various seismic characteristics are investigated by applying the proposed design method to a numerical example of a 10?story building structure. The cost effectiveness of viscoelastically damped structural system is also evaluated by comparing the life-cycle cost of the structure without viscoelastic dampers. The results show that the viscoelastic damper is effective in a region of low to moderate seismicity.

• Journal of Korean Society of Transportation
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• v.23 no.7 s.85
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• pp.99-110
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• 2005

Total travel cost of route which connects origin with destination (O-D) is consist of the total sum of link travel cost and route perception cost. If the link perception cost is different according to the origin and destination, optimal route search has limitation to reflect the actual condition by route enumeration problem. The purpose of this study is to propose optimal route searching formulation and algorithm which is enable to reflect different link perception cost by each route, not only avoid the enumeration problem between origin and destination. This method defines minimum unit of route as a link and finally compares routes using link unit costs. The proposed method considers the perception travel cost at both origin and destination in optimal route searching process, while conventional models refect the perception cost only at origin. However this two-way searching algorithm is still not able to guarantee optimum solution. To overcome this problem, this study proposed an orign based optimal route searching method which was developed based on destination based optimal perception route tree. This study investigates whether proposed numerical formulas and algorithms are able to reflect route perception behavior reflected the feature of origin and destination in a real traffic network by the example research including the diversity of route information for the surrounding area and the perception cost for the road hierarchy.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.115-130
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• 2005

This paper presents the effects of indirect costs on Life-Cycle-Cost(LCC) effective optimum design of steel-box girder bridges. The LCC formulations considered in the LCC optimization of the bridges consist of initial cost and expected rehabilitation costs including repair/replacement costs, loss of contents or fatality and injury losses, and indirect costs such as road user costs and indirect socio-economic losses. To demonstrate the LCC-effectiveness for optimum design of the bridges, an actual steel box girder bridge having two continuous spans(2@50m=100m) is considered as a numerical example. And also, in this paper, various sensitivity analyses are performed to investigate the effects of indirect costs caused by traffic conditions such as number of detour route, number of lane on detour route, length of detour route, and traffic volumes on the LCC-effective optimum design. From the numerical investigations, it may be concluded that indirect costs caused by traffic network may sensitively influence on the LCC-effective optimum design of steel-box girder bridges. Therefore, it may be stated that the traffic conditions should be considered as one of the important items in the LCC-effective optimum design of the bridges.

• Journal of Korean Society of Transportation
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• v.8 no.2
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• pp.109-118
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• 1990

본 고는 도로선형 설계에 확율 및 경제요소를 반영시키는 방법과 그에 따른 효과를 파악하는데 목적을 두고 있다. 접근방법은 도로사용자 비용과 도로시공 및 유지관리 비용 등을 포함하는 총비용을 예상비용함수로 나타내어 이 비용함수를 최소화함으로써 최적 도로선형 설계방법을 찾는 것이다. 이와 더불어 본 고는 이 개념에 의한 최적 설계방법을 등반차선(Climbing lane)의 설계에 적용하였다. 즉, 오르막길의 경사 및 거리에 따른 등반차선의 최적 위치를 찾기 위해 우선 오르막길에서의 승용차와 트럭의 속도분포를 찾아내고 예상예비함수를 등식화하여 그 최적해를 구함으로써 등반차선의 최적 위치를 구하였다. 현재 등반차선의 설계과정(AASHTO, 1984)은 트럭 주행능력에 따른 가정과 트럭과 승용차의 최대 속도 차이를 임의로 선택하여 등반차선의 최적 위치를 찾고 있다. 따라서 본 고에서는 기존 등반차선 설계방법과 새로운 설계방법을 상호 비교하면서 새로운 방법의 타당성과 그에 따른 설계이점들을 증명하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.245-251
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• 2004

Determination the optimal containership size is the most important factor for competitiveness if shipping companies. Accordingly, the objective if this research is determining the optimal containership size by service routes. Total shipping cost is calculated at the ground if capital cost, vessel operation costs, voyage costs, port charge and miscellaneous cost for 'Europe-Far East', 'Far East-North America' and 'Europe-Far East-North America' Services. Finally, the optimal containership size was utilized through total shipping cost, slot quantity if containership and average throughput by containership.