• Interaction and multiscale mechanics
• /
• 제2권3호
• /
• pp.263-276
• /
• 2009

This paper is intended to investigate interaction response of a train running over a suspension bridge undergoing support settlements. The suspension bridge is modeled as a single-span suspended beam with hinged ends and the train as successive moving oscillators with identical properties. To conduct this dynamic problem with non-homogeneous boundary conditions, this study first divides the total response of the suspended beam into two parts: the static and dynamic responses. Then, the coupled equations of motion for the suspended beam carrying multiple moving oscillators are transformed into a set of nonlinearly coupled generalized equations by Galerkin's method, and solved using the Newmark method with an incremental-iterative procedure including the three phases: predictor, corrector, and equilibrium-checking. Numerical investigations demonstrate that the present iterative technique is available in dealing with the dynamic interaction problem of vehicle/bridge coupling system and that the differential movements of bridge supports will significantly affect the dynamic response of the running vehicles but insignificant influence on the bridge response.

• 산업경영시스템학회지
• /
• 제22권51호
• /
• pp.211-220
• /
• 1999

The purpose of this study is the necessity of collaboration, equilibrium or the differences of examination items about certification system which is focused on products, such as KS, formal approval, and ISO 9000 family, QS 9000, etc, for Quality management system. We make expert group control this problem. Also we make examination items to be united. And the differences of certification body and personnel necessary is dissolved by proper instruction. Examination process and corrective maintenance should be improved by clarity, fairness and reliability. Problems through preparation for certification and certified company should be focused on reform of consciousness of top management and continuous instruction. And desirable solution for mutual certification problem and others should be found by information interchange system of international cooperation.

• 대한조선학회논문집
• /
• 제41권2호
• /
• pp.98-105
• /
• 2004

This study focuses on an analytical approach to calculate four crane lifting forces for heavy ship hull blocks considering elongations of lilting slings. Four-crane-lifting is a redundant problem. During lifting procedures, in addition to the force and moment equilibrium equations, a compatibility condition is introduced to determine 4 unknown lifting forces. For verification of the method, a ship hull block with field measurements data is analyzed and the result shows that the information obtained by current method could be useful to engineers to conduct lifting work at shipyards.

• Structural Engineering and Mechanics
• /
• 제4권1호
• /
• pp.49-59
• /
• 1996

This paper considers large deflection problem of a simply supported beam with variable are length subjected to a point load. The beam has one of its ends hinged and at a fixed distance from this end propped by a frictionless support over which the beam can slide freely. This highly nonlinear flexural problem is solved by elliptic-integral method and shooting-optimization technique, thereby providing independent checks on the new solutions. Because the beam can slide freely over the frictionless support, there is a maximum or critical load which the beam can carry and it is dependent on the position of the load. Interestingly, two possible equilibrium configurations can be obtained for a given load magnitude which is less than the critical value. The maximum arc-length was found to be equal to about 2.19 times the fixed distance between the supports and this value is independent of the load position.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 D
• /
• pp.2240-2242
• /
• 2001

A rotary double inverted pendulum, the nonlinear system has a regulation problem. In this paper, we linearize the nonlinear system at the upright equilibrium position. The linearized system can be expressed in state space. To maintain the upright position, we design a feedback controller using LQR(Linear Quadratic Regulator) algorithm. Then we simulate the system with third-order Adams Bashforth Moulton Method. The simulated result shows that the applied algorithm is effective for the regulation problem.

• 대한전기학회논문지:전력기술부문A
• /
• 제53권8호
• /
• pp.484-489
• /
• 2004

When the energy resource available to a particular plant (be it coal, oil, gas, water, or nuclear fuel) is a limiting factor in the operation of the plant, the entire economic dispatch calculation must be done differently. Each economic dispatch calculation must account for what happened before and what will happen in the future. This paper presents a formulation and a solution method for the optimization problem with a fuel constraint in a competitive electricity market. Take-or- Pay (TOP) contract for an energy resource is the typical constraint as a limiting factor. Two approaches are proposed in this paper for modeling the dispatch calculation in a market mechanism. The approaches differ in the subject who considers and inserts the fuel-constraint into its optimization problem. Market operator and each power producer having a TOP contract are assumed as such subjects. The two approaches are compared from the viewpoint of profits. surplus. and social welfare on the basis of Nash Equilibrium.

• Structural Engineering and Mechanics
• /
• 제10권2호
• /
• pp.181-195
• /
• 2000

A two-step procedure for the application of non linear constrained programming to the limit analysis of rigid brick-block systems with no-tension and frictional interface is implemented and applied to various masonry structures. In the first step, a linear problem of programming, obtained by applying the upper bound theorem of limit analysis to systems of blocks interacting through no-tension and dilatant interfaces, is solved. The solution of this linear program is then employed as initial guess for a non linear and non convex problem of programming, obtained applying both the 'mechanism' and the 'equilibrium' approaches to the same block system with no-tension and frictional interfaces. The optimiser used is based on the sequential quadratic programming. The gradients of the constraints required are provided directly in symbolic form. In this way the program easily converges to the optimal solution even for systems with many degrees of freedom. Various numerical analyses showed that the procedure allows a reliable investigation of the ultimate behaviour of jointed structures, such as stone masonry structures, under statical load conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권9호
• /
• pp.4188-4206
• /
• 2016

Power control is widely used to reduce co-channel interference in wireless networks and guarantee the signal-to-interference plus noise ratio (SINR) of ongoing connections. This technique is also effective for wireless body area networks (WBANs). Although achieving satisfactory SINR is important for WBAN users, they may not be willing to achieve it at arbitrarily high power levels since power is a scarce resource in WBANs. Besides, for WBANs with different purposes, the QoS requirements and concern about the power consumption may be different. This motivates us to formulate the power control problem using the concepts from microeconomics and game theory. In this paper, the QoS objective is viewed as a utility function, which represents the degree of user satisfaction, while the power consumption is viewed as a cost function. The power control problem consequently becomes a non-cooperative multiplayer game, in which each player tries to maximize its net utility, i.e., the utility minus the cost. Within this framework, we investigate the Nash equilibrium existence and uniqueness in the game and derive the best response solution to reach the Nash equilibrium. To obtain the optimal transmission power in a distributed way, we further propose a utility-based and QoS-aware power control algorithm (UQoS-PCA). Tunable cost coefficient in UQoS-PCA enables this scheme to be flexible to satisfy diverse service requirements. Simulation results show the convergence and effectiveness of the proposed scheme as well as improvements over existing algorithm.

• 대한교통학회지
• /
• 제25권6호
• /
• pp.161-170
• /
• 2007

본 연구에서는 통행배정 모형이 갖는 여러 가지 가정 중 대칭적 통행비용 함수를 갖는 가정을 극복할 수 있는 방법에 대해 살펴보았다. 통행배정 문제에 있어서 대칭적 비용함수 가정이라는 것은 링크의 통행비용은 다른 링크의 교통량에 전혀 영향을 받지 않는 않으면서, 동시에 해당 링크를 통과하는 단하나의 수단에 의해서만 결정된다는 의미이다. 본 연구에서는 이러한 가정을 극복할 수 있는 비대칭 통행배정모형의 특성을 살펴보고, 그 해석 모형에 대해 고찰하였다. 이 때 대표적 비대칭 통행배정 문제인 다수단 통행배정 모형을 중심으로 문제를 정의하여 검토하였다. 대각화(Diagonalized) 알고리즘과 Column Generation에 기반한 heuristic 모형을 다수단 통행배정 모형에 적용하여 그 결과를 분석하였다. 그 과정을 통해 대각화 알고리즘은 초기해의 수단과 수렴기준 수단에 따라 서로다른 해를 갖는 복수의 평형해(Equilibria)특성을 가지고 있음을 확인하였다. 그에 비해 Column Generation에 기반한 heuristic 모형은 Euclidean Norm을 이용한 부분최적화를 통해 복수의 평형해(Equilibria)에 관한 문제점을 개선할 수 있었다.

• 한국콘텐츠학회논문지
• /
• 제19권4호
• /
• pp.79-90
• /
• 2019

최근 들어 다수의 클라우드 서비스 제공자가 클라우드 컴퓨팅 서비스를 제공함으로써 각 제공자는 더 많은 사용자를 확보하기 위해 치열한 경쟁을 벌이고 있다. 서비스 제공자별 컴퓨팅 자원의 구성 및 서비스 제공 부하가 다르기 때문에 사용자는 다양한 수준의 서비스 품질을 경험할 수 있다. 따라서 클라우드 서비스 시장에서 더 많은 사용자를 확보하여 수익을 최대화하기 위해서는 서비스 품질에 대한 가장 합리적인 가격을 결정하는 것이 매우 중요하다. 본 연구에서는 두 명의 서비스 제공자가 존재하는 멀티미디어 클라우드 서비스 시장에서 두 제공자 간 서비스 가격 경쟁에 대해 다룬다. 두 명의 클라우드 서비스 제공자가 최적의 가격을 결정하여 상호 경쟁하고 자신의 이익을 최대화할 수 있는 가격 산정 방법을 비협력 게임 이론으로 설명한다. 이를 위해 멀티미디어 클라우드 서비스의 제공 프로세스를 대기행렬 시스템으로 모형화하고, 분석 결과를 바탕으로 복점 멀티미디어 클라우드 서비스 시장에서 가격 경쟁 문제를 제안한다.