• 산업경영시스템학회지
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• 제20권43호
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• pp.67-79
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• 1997

In this paper we develop the integrated software that can compare algorithms of the minimum cost flow problem using PC. The chosen algorithms are the network simplex method, dual network simplex method, and out-of-kilter method, which methods correspond to primal, dual, and primal-dual approach respectively. We also present the improved methods obtaining the initial solution to increase the efficiency of algorithms, and experiment results shown the difference between the entering(dropping) selection rules.

• International Journal of Contents
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• 제7권2호
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• pp.6-10
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• 2011

The directional MAC (DMAC) protocol improves the spatial reuse, but directional packets on the control channel cause the deafness problem. In this paper, we propose a tone dual-channel DMAC protocol for mobile ad-hoc networks. In the proposed MAC protocol, the use of omnidirectional transmissions using an omnidirectional out-of-band tone solves the deafness problem and decrease packet collisions on the control channel. The use of an omnidirectional out-of-band tone also mitigates the hidden terminal problem. We use the negative CTS (NCTS) mechanism to solve the exposed terminal problem. The throughput performance of the proposed MAC protocol is confirmed by simulations using the Qualnet simulator.

• Journal of Power Electronics
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• 제19권2호
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• pp.454-462
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• 2019

When compared to traditional bridge-type inverters, the dual-buck inverter has a higher reliability due to the fact that its bridge legs do not have a shoot-through problem. In this paper, the working principle of the dual-buck inverter is analyzed. A comparison of the working modes under full-cycle and half-cycle control is discussed. With half-cycle control, the inverter can realize a higher efficiency. However, this results in current zero-crossing distortion. The corresponding control strategy of the dual-buck inverter is proposed in order to realize both high efficiency and low current harmonic distortion. In addition, the system stability is analyzed. Dead-time is unnecessary due to the advantages of the topology. Thus, the current harmonic distortion can be further reduced. An inverter with the proposed control strategy has the advantages of high reliability, high efficiency and low current harmonic distortion. Finally, simulation and experimental results are given to verify the theoretical analysis.

• 대한산업공학회지
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• 제28권1호
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• pp.99-104
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• 2002

This paper presents a method of sensitivity analysis for the infeasible interior point method when a new variable is introduced. For the sensitivity analysis in introducing a new variable, we present a method to find an optimal solution to the modified problem. If dual feasibility is satisfied, the optimal solution to the modified problem is the same as that of the original problem. If dual feasibility is not satisfied, we first check whether the optimal solution to the modified problem can be easily obtained by moving only dual solution to the original problem. If it is possible, the optimal solution to the modified problem is obtained by simple modification of the optimal solution to the original problem. Otherwise, a method to set an initial solution for the infeasible interior point method is presented to reduce the number of iterations required. The experimental results are presented to demonstrate that the proposed method works better.

• East Asian mathematical journal
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• 제33권3호
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• pp.265-269
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• 2017

In this paper, we formulate a sufficient optimality theorem for the robust optimization problem (UP) under (V, ${\rho}$)-invexity assumption. Moreover, we formulate a Mond-Weir type dual problem for the robust optimization problem (UP) and show that the weak and strong duality hold between the primal problems and the dual problems.

• Journal of applied mathematics & informatics
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• 제26권5_6호
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• pp.819-837
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• 2008

A mixed type dual to the control problem in order to unify Wolfe and Mond-Weir type dual control problem is presented in various duality results are validated and the generalized invexity assumptions. It is pointed out that our results can be extended to the control problems with free boundary conditions. The duality results for nonlinear programming problems already existing in the literature are deduced as special cases of our results.

• East Asian mathematical journal
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• 제17권2호
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• pp.375-383
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• 2001

In this paper we deal with the duality theory of optimality for an optimal control problem governed by a class of second order evolution equations. First we establish the dual control systems by using conjugate functions and then associate them to the original optimization problem.

• 대한수학회보
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• 제35권4호
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• pp.727-739
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• 1998

We discuss dual algebras generated by a contraction and properties $({\mathbb}A_{m,n})$ which arise in the study of the problem of solving systems of the predual of a dual algebra. In particular, we study membership for the class ${\mathbb}A_1,{{\aleph}_0 }$. As some examples we consider dual algebras generated by a Jordan block.

• Journal of Applied and Pure Mathematics
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• 제4권3_4호
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• pp.211-219
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• 2022

We study MDS(maximum distance separable) self-dual codes over Galois ring R = GR(2^m, r). We prove that there exists an MDS self-dual code over R of length n if (n - 1) divides (2^r - 1), and 2^m divides n. We also provide the current state of the problem for the existence of MDS self-dual codes over Galois rings.

• Design & Manufacturing
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• 제15권1호
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• pp.57-65
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• 2021

Pump cap is a product that is widely used due to its ease of use and simple operation. These pump caps are applied to heterogeneous functional cosmetics and are being developed as dual pump caps. However, the conventional dual pump cap has a problem in that it is inconvenient to use and leakage occurs. In addition, it is formed of a plurality of materials, and there is a problem that is difficult to recycle. Lately, since the problem of environmental pollution is getting serious, the dual pump cap, which is difficult to recycle, cannot be used. Currently, eco-friendliness has been considered in Korea, and there are no dual pump cap containers with excellent sealing performance. Therefore, in this study, a dual pump cap container made of eco-friendly material was designed. In addition, finite element analysis was performed to verify the design feasibility of the product.