• ETRI Journal
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• v.39 no.3
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• pp.345-352
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• 2017

Traffic management is a highly beneficial mechanism for satisfying quality-of-service requirements and overcoming the resource scarcity problems in networks. This paper introduces an optimal connection admission control mechanism to decrease the packet loss ratio and end-to-end delay in cognitive radio sensor networks (CRSNs). This mechanism admits data flows based on the value of information sent by the sensor nodes, the network state, and the estimated required resources of the data flows. The number of required channels of each data flow is estimated using a proposed formula that is inspired by a graph coloring approach. The proposed admission control mechanism is formulated as a semi-Markov decision process and a linear programming problem is derived to obtain the optimal admission control policy for obtaining the maximum reward. Simulation results demonstrate that the proposed mechanism outperforms a recently proposed admission control mechanism in CRSNs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1779-1786
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• 2002

When the topology optimization is applied to the design of compliant mechanism, unexpected displacements of input and output port are generated since the displacement control is not included in the formulation. To devise a more precise mechanism, displacement constraint is formulated using the mutual potential energy concept and added to multi-objective function defined with flexibility and stiffness of a structure. The optimization problem is resolved by using Finite Element Method(FEM) and Sequential Linear Programming(SLP). Design examples of compliant mechanism with displacement constraint are presented to validate the proposed design method.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1441-1446
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• 2003

The design optimization of the plate heat exchanger with staggered pin arrays for a fixed volume is performed numerically. The flow and thermal fields are assumed to be a streamwise-periodic flow and heat transfer with constant wall temperature and they are solved by using the finite volume method. The optimization is carried out by using the sequential linear programming (SLP) method and the weighting method is used for solving the multi-objective problem. The results show that the optimal design variables for the weighting coefficient of 0.5 are as follows; S=6.497mm, P=5.496mm, $D_1=0.689mm$, and $D_2=2.396mm$. The Pareto optimal solutions are also presented.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.24-29
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• 1996

If the LP problem doesn't have the optimal soultion uniquely, the solution fo the primal-dual barrier method converges to the interior point of the optimal face. Therefore, when the optimal vertex solution or the optimal basis is required, we have to perform the additional procedure to recover the optimal basis from the final solution of the interior point method. In this paper the exisiting methods for recovering the optimal basis or identifying the optimal solutions are analyzed and the new methods are suggested. This paper treats the two optimal basis recovery methods. One uses the purification scheme and the simplex method, the other uses the optimal face solutions. In the method using the purification procedure and the simplex method, the basic feasible solution is obtained from the given interior solution and then simplex method is performed for recovering the optimal basis. In the method using the optimal face solutions, the optimal basis in the primal-dual barrier method is constructed by intergrating the optimal solution identification technique and the optimal basis extracting method from the primal-optimal soltion and the dual-optimal solution.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.40-43
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• 2000

This paper is concerned with development of an efficient Ρ-median approach applicable to large cell formation(CF) problems. A two-phase methodology that seeks to minimize the number of exceptional elements is proposed. In phase I, two efficient Ρ-median formulations which contain fewer binary variables than existing Ρ-median formulations are constructed. These make it possible to implement large CF problem within reasonable computer runtime with commercially available linear integer programming codes. Given the initial cell configuration found with the new p-median formulations, in phase II bottleneck machines and parts are reassigned to reduce the number of exceptional elements. This procedure has the flexibility to provide the cell designer with alternative solutions. Test results on large CF problems show a substantial efficiency of the new Ρ-median formulations.

• Structural Engineering and Mechanics
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• v.31 no.3
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• pp.277-296
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• 2009

The paper investigates the dynamic behaviour of stiffened panels. The coupled differential equations for eccentric stiffening configuration are first derived. Then a semi-analytical procedure for dynamic analysis of stiffened panels is presented. Unlike finite element or finite strip methods, where the plate is discretized into a set of elements or strips, the plate in this procedure is treated as a single element. The potential energy of the structure is first expressed in terms generalized functions that describe the longitudinal and transverse displacement profiles. The resulting non-linear strain energy functions are then transformed into unconstrained optimization problem in which mathematical programming techniques are employed to determine the magnitude of the lowest natural frequency and the associated mode shape for pre-selected plate/stiffener geometric parameters. The described procedure is verified with other numerical methods for several stiffened panels. Results are then presented showing the variation of the natural frequency with plate/stiffener geometric parameters for various stiffening configurations.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.339-347
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• 2001

A probabilistic optimum design method of the base isolation system consisting of linear spring, viscous damper and frictional element is presented. For the probabilistic approach, the base excitation is assumed to be a stationary Gaussian filtered random process. For optimum design, the objective function and constraints are derived based on the stochastic responses of the system. As a numerical example, the optimum design problem of a three-story base isolated shear type structure is formulated and solved by the sequential quadratic programming method. As a result, the effects of variation of design variables such as parameters of the base isolation system and the mass of base on the objective function and constraints are investigated and the optimum parameters of the base isolation system under study are derived.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.5
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• pp.426-432
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• 2000

A novel mixed-integer linear programming model for the short-term scheduling of a sequential multipurpose batch plant is addressed. First, a time slot domain to each unit is introduced. By assigning each time slot to a product, we obtain the production sequence that minimizes makespan. For multiple-unit assignment problem where a few parallel units with the same function exist, production paths are defined for the distinction of the same stage with a different unit. As a second issue, the model adapted for sequence dependent changeover is presented. For a time slot of a unit, if a product is assigned to the time slot and a different product is assigned to the adjacent time slot, the changeover time considering this situation is included. The performance of the proposed models are illustrated through two examples.

• Journal of the Korean Operations Research and Management Science Society
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• v.10 no.2
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• pp.83-87
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• 1985

분해원리(decomposition principle)은 선형계획법문제 중에서도 블록대각구조를 가진 특수 모형에 의한 해법으로 잘 알려져 있다. 그런데 일반적으로 소개되어 있는 분해원리는 변수가 비음의 조건을 가진 문제에 대한 해법이다. 블록대각 구조를 가진 선형계획법 문제는 잘 알려져 있는 바와 같이 하부구조를 가진 기관의 경영, 여러가지 종류의 사료배합 문제 등에 일어난다. 그런데 이런 문제의 대부분의 경우가 변수는 상.하한을 가지는 경우가 된다. 이 논문은 비음의 조건을 가지는 문제에 대한 분해원리를 발전시켜 이런 변수가 상.하한을 가지는 일반적인 문제를 풀 수 있도록 하고자 하는 것이다. 변수가 상.하한을 가지게 되며 우선 진입변수, 탈락변수를 결정하는 문제, 1단계(phase 1) 문제 등에 어려움이 나타난다. 이 논문은 이런 어려움들을 극복하고 나아가 주기억 공간이 제한되어 있는 소형전산기에 알맞는 계산방법을 연구하고자 한다.

• Journal of the military operations research society of Korea
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• v.22 no.2
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• pp.141-152
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• 1996

Currently, North Korea is increasing strategic weapons such as MIG-29, SUCD missle, Nodong #1 missle, etc. This paper focuses on developing the deciding the number of aircraft required for air to surface mission against strategic targets in North Korea. The model is developed under assumptions that weapon types of aircrafts are known and killing probabilities in each case can be estimated. The model is derived on the basis of the TAIM(Theater Air Interdiction Model) which is used in DOD of U.S.A. We utilizes recursive linear programming and dynamic technique in the model in order to solve aircraft allocations for strategic targets which are provided in day time basis. The required number of aircrafts can be obtained from the model output. Finally an example problem is solved using techniques developed in the paper.