• 한국경영과학회지
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• 제32권4호
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• pp.19-35
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• 2007

This study is for detecting the Braess Paradox by stable dynamics in general transportation networks. Stable dynamics, suggested by Nesterov and de Palma[18], is a new model which describes and provides a stable state of congestion in urban transportation networks. In comparison with user equilibrium model based on link latency function in analyzing transportation networks, stable dynamics requires few parameters and is coincident with intuitions and observations on the congestion. Therefore it is expected to be an useful analysis tool for transportation planners. The phenomenon that increasing capacity of a network, for example creating new links, may decrease its performance is called Braess Paradox. It has been studied intensively under user equilibrium model with link latency function since Braess[5] demonstrated a paradoxical example. However it is an open problem to detect the Braess Paradox under stable dynamics. In this study, we suggest a method to detect the Paradox in general networks under stable dynamics. In our model, we decide whether Braess Paradox will occur in a given network. We also find Braess links or Braess crosses if a network permits the paradox. We also show an example how to apply it in a network.

• 대한교통학회지
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• 제20권4호
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• pp.95-107
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• 2002

혼잡세나 한계비용요금정책은 교통시설의 이용에 혼잡이 있거나 서비스 제공에 규모의 경제가 존재하는 경우 강력히 추천되는 정책도구이다. 그러나 본 논문에서는 그와 같은 시각은 당해 시설 서비스 시장만 고려할 때만 타당할 뿐 다른 시장과의 상호작용을 염두에 둔 일반균형적인 관점에서는 일반적으로 성립되지 않음을 보인다. 또한 각 정책에 대해 혼잡세나 한계비용요금정책이 실패로 돌아가는 예를 구체적으로 보이고 그에 대한 정책적 대안이 제시된다. 이 과정에서 이용량 제한이나 평균비용 요금정책 등이 놀랍게도 전통적 수단보다 우수한 정책으로 등장한다. 그러나, 이 결과는 특수한 상황에서만 성립하는 것으로 이와 관련된 연구과제들이 결론적으로 제시된다.

• 대한기계학회논문집B
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• 제26권8호
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• pp.1172-1182
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• 2002

In the present study a general criterion for local thermal equilibrium is presented in terms of parameters of engineering importance which include the Darcy number, the effective Prandtl number of fluid, and the Reynolds number. For this, an order of magnitude analysis is performed for the case when the effect of convection heat transfer is dominant in a porous structure. The criterion proposed in this study is more general than the previous criterion suggested by Carbonell and Whitaker, because the latter is applicable only when conduction is the dominant heat transfer mode in a porous medium while the former can be applied even when convection heat transfer prevails. In order to check the validity of the proposed criterion for local thermal equilibrium, the forced convection phenomena in a porous medium with a microchanneled structure subject to an impinging jet are studied using a similarity transformation. The proposed criterion is also validated with the existing experimental and numerical results for convection heat transfer in various porous materials that include some of the parameters used in the criterion such as a microchannel heat sink with a parallel flow, a packed bed, a cellular ceramic, and a sintered metal. It is shown that the criterion presented in this work well-predicts the validity of the assumption of local thermal equilibrium in a porous medium.

• 무역상무연구
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• 제42권
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• pp.67-85
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• 2009

In English Law it seems that it is essential to apply the principle of equilibrium in the contract, however, it does not seemed to apply as the general rule of the principle of contract. Especially it seems that English Court didn't pay attention to the principle of equilibrium in 18th century. If one of the party do not appeal the equilibrium of the contract, it does not make any difference even today. However the Court may cancel or withdraw the construction of contract between the parties where the principle of equilibrium is damaged by fundamental problems like just-price. In French Law it seems that they have more wide definition of the principle of equilibrium. The French Court may consider that the application of good faith is the performance of condition of the contract between the parties and has no power to relieve of one party of his expressed obligations or warranty. In German Law, it seems that the principle of good faith is fundamental to take into account interest of the parties. They may agree to supply information or not to interfere with a commercial agent regarding performance and maintenance of the contract.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.61-68
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• 2000

In general, the design of membrane structures takes three steps. The first is shape finding analysis which is determination of initial equilibrium geometry with uniform stresses. The second step involve the computation of the stress-deformation to get completed membrane under various load conditions. The third step is to divide the membrane structures into several plan strips from the initial equilibrium states. This procedure is needed because of the initial shape has usually undevelopable curved surface and is called as "cutting patterns generation". By introducing this work, the deformation due to the initial stress is removed and approximate cutting patterns are generated. In this approach, however, material properties is not considered, therefore the error between the design stresses and actual stresses during the fabrication of plan strips should be occurred. In this paper, actual equilibrium shape analysis procedure for HP shape models is presented. The deviations of stresses between the design stresses and actual stresses are estimated.

• Journal of Mechanical Science and Technology
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• 제18권9호
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• pp.1529-1536
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• 2004

A structure is broken down into a number of substructures by means of the finite element method and the substructures are synthesized for the complete structure. The divided substructures take two types: fixed-free and free-free elements. The flexibility and stiffness matrices of the free-free elements are the Moore-Penrose inverse of each other. Thus, it is not easy to determine the equilibrium equations of the complete structure composed of two mixed types of substructures. This study provides the general form of equilibrium equation of the entire structure through the process of assembling the equilibrium equations of substructures with end conditions of mixed types. Applications demonstrate that the proposed method is effective in the structural analysis of geometrically complicated structures.

• 대한교통학회지
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• 제18권2호
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• pp.91-101
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• 2000

현재 교통경제학에서 통용되는 도로시설의 최적 혼잡통행료는 분석의 대상을 개별 시설로 국한시킨 부분적인 사회복지 최적화모형에서 도출한 것이다. 그렇지만 특정 시설에 국한하여 부과하는 경우, 부분균형에서 해당 시설의 최적 혼잡통행료는 교통망 전체로서 사용자 후생을 최대화시킬 수 있는지 불분명하다. 특정 시설에 부과된 통행료는 여타 대체시설의 교통량을 증가시키는 파급효과를 동반하기 때문이다. 본 연구에서는 이와 같은 기존 이론의 취약점을 극복하는 대안적 접근방법이 제시되었다. 본 연구의 주된 차이점은 여러 개의 교통시설 이외에도 일반 소비재가 유통되는 시장에 대한 일반균형분석을 통해 최적의 혼잡통행료를 산출한 것이고, 이러한 접근방법은 기존 이론과는 차별화된 분석결과를 가져왔다. 이러한 일반균형분석에서 모든 교통시설에 혼잡통행료를 부과하는 경우, 개별 교통시설의 최적 혼잡통행료는 해당 시설의 한계비용이 한계효용과 일치시키는 값이었다. 이러한 분석결과는 부분균형에서 유도된 기존의 결과와 일치한다. 반면 특정 교통시설에 국한하여 혼잡통행료를 부과하는 경우, 혼잡통행료는 대체시설로의 수요 전이효과등을 반영하여 부분균형에서의 최적 혼잡통행료에 비해 낮은 값으로 나타났다.

• Journal of applied mathematics & informatics
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• 제29권3_4호
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• pp.621-639
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• 2011

The purpose of this paper is to introduce a general iterative process by viscosity approximation method with parallel method to ap-proximate a common element of the set of solutions of a mixed equilibrium problem and of the set of common fixed points of a finite family of $k_i$-strict pseudo-contractions in a Hilbert space. We obtain a strong convergence theorem of the proposed iterative method for a finite family of $k_i$-strict pseudo-contractions to the unique solution of variational inequality which is the optimality condition for a minimization problem under some mild conditions imposed on parameters. The results obtained in this paper improve and extend the corresponding results announced by Liu (2009), Plubtieng-Panpaeng (2007), Takahashi-Takahashi (2007), Peng et al. (2009) and some well-known results in the literature.

• 대한수학회보
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• 제38권1호
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• pp.71-79
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• 2001

The purpose of this paper is to prove new equilibrium existence theorems of social systems with coordination under general conditions on the preference correspondence in locally convex spaces, and we also give an example which the previous existence results on SSC do not work but our theorem can be applied.

• 대한안전경영과학회지
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• 제13권1호
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• pp.127-131
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• 2011

Even if there are no causing factors such as car crash and road works, traffic congestion come from traffic growth on the road. In this case, estimation of traffic flow helps find the solution of traffic congestion problem. In this paper, we present a optimization model which used on traffic equilibrium problem and studied the problem of inverting shortest path sets for complex traffic system. And we also develop pivotal decomposition algorithm for reliability function of complex traffic system. Several examples are illustrated.