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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Operations Research and Management Science Society
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Journal DOI :
The Korean Operations and Management Science Society
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Volume & Issues
Volume 32, Issue 4 - Dec 2007
Volume 32, Issue 3 - Sep 2007
Volume 32, Issue 2 - Jun 2007
Volume 32, Issue 1 - Mar 2007
Selecting the target year
Prioritized Dynamic Rate Scheduling for Interactive GEO Satellite Networks
Chang, Kun-Nyeong ;
Journal of the Korean Operations Research and Management Science Society, volume 32, issue 3, 2007, Pages 1~15
In this paper, the return link of interactive GEO satellite network providing multimedia services is considered. First, we classify data by delay characteristics, and analyze the numbers of expected lost packets and expected delay packets for each data class of each terminal. Next we mathematically formulate optimal rate scheduling model to minimize the weighted sum of the numbers of expected lost packets and expected delay packets considering priority of each data class. We also suggest a dynamic rate scheduling scheme based on Lagrangean relaxation technique and subgradient technique to solve the proposed model in a fast time. Extensive experiments show that the proposed scheme provides encouraging results.
A Design Problem of a Service System with Bi-functional Servers
Kim, Sung-Chul ;
Journal of the Korean Operations Research and Management Science Society, volume 32, issue 3, 2007, Pages 17~31
In this paper, we consider a service system with bi-functional servers, which can switch between the primary service room and the secondary room. A service policy is characterized by the switching paints which depend on the queue length in the primary service room and the service level requirement constraint of the secondary room. The primary service room is modeled as a Markovian queueing system and the throughput of the primary service room is function of the total number of bi-functional servers. the buffer capacity of the primary service room, and the service policy. There is a revenue obtained from throughput and costs due to servers and buffers. We study the problem of simuitaneously determining the optimal number of servers, buffer capacity, and service policy to maximize profit of the service system, and develop an algorithm which can be successfully applied with the small number of computations.
Resouce Allocation for Multiuser OFDM Systems
Chung, Yong-Joo ; Paik, Chun-Hyun ; Kim, Hu-Gon ;
Journal of the Korean Operations Research and Management Science Society, volume 32, issue 3, 2007, Pages 33~46
This study deals with the adaptive multiuser OFDM (Orthogonal Frequency Division Multiplexing) system which adjusts the resource allocation according to the environmental changes in such as wireless and quality of service required by users. The resource allocation includes subcarrier assignment to users, modulation method and power used for subcarriers. We first develop a general optimization model which maximizes data throughput while satisfying data rates required by users and total power constraints. Based on the property that this problem has the 0 duality gap, we apply the subgradient dual optimization method which obtains the solution of the dual problem by iteration of simple calculations. Extensive experiments with realistic data have shown that the subgradient dual method is applicable to the real world system, and can be used as a dynamic resource allocation mechanism.
Elimination of Subtours Obtained by the Out-of-Kilter Algorithm for the Sequential Ordering Problem
Kwon, Sang-Ho ;
Journal of the Korean Operations Research and Management Science Society, volume 32, issue 3, 2007, Pages 47~61
This paper presents two elimination methods of subtours, which is obtained by applying the Out-of-Kilter algorithm to the sequential ordering problem (SOP) to produce a feasible solution for the SOP. Since the SOP is a kind of asymmetric traveling salesman problem (ATSP) with precedence constraints, we can apply the Out-of-Kilter algorithm to the SOP by relaxing the precedence constraints. Instead of patching subtours, both of two elimination methods construct a feasible solution of the SOP by using arcs constructing the subtours, and they improve solution by running 3-opt and 4-opt at each iteration. We also use a perturbation method. cost relaxation to explore a global solution. Six cases from two elimination methods are presented and their experimental results are compared to each other. The proposed algorithm found 32 best known solutions out of the 34 instances from the TSPLIB in a reasonable time.
A Traffic Assignment Model in Multiclass Transportation Networks
Park, Koo-Hyun ;
Journal of the Korean Operations Research and Management Science Society, volume 32, issue 3, 2007, Pages 63~80
This study is a generalization of 'stable dynamics' recently suggested by Nesterov and de Palma. Stable dynamics is a new model which describes and provides a stable state of congestion in urban transportation networks. In comparison with user equilibrium model that is common 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. An equilibrium in stable dynamics needs only maximum flow in each arc and Wardrop Principle. In this study, we generalize the stable dynamics into the model with multiple traffic classes. We classify the traffic into the types of vehicle such as cars, buses and trucks. Driving behaviors classified by age, sex and income-level can also be classes. We develop an equilibrium with multiple traffic classes. We can find the equilibrium by solving the well-known network problem, multicommodity minimum cost network flow problem.
Economic Impacts of Information and Communications Technology Industry In Korea Using Input-Output Tables
Kim, Do-Whan ;
Journal of the Korean Operations Research and Management Science Society, volume 32, issue 3, 2007, Pages 81~96
This paper analyses the Korean information and communication technology supply side across the economy using 1995, 2000 and 2003 input-output tables. Input-output analysis considers inter-industry relations in an economy, depicting how the output of one industry goes to another industry where it serves as an input, and thereby makes one industry dependent on another both as customer of output and as supplier of Inputs. It can be evaluated that the recent growth of Korean ICT sector has come from the development of communication service and equipment industry and software industry. Although the high performance and positive revealed comparative advantages in ICT manufacturing sector, the value added and employment in that sector are not satisfactory. It may reflect in part high portion of imported intermediate goods in ICT manufacturing. However, it is fortunate that ICT services, which accounted for relatively high value added, induce the development of ICT manufacturing and follow strong export performance. Moreover, it is expected that the software sector with high value added and employment will be a major driver of ICT growth.
Does the Understanding of Core Competencies Matter to IT Outsourcing Performance?
Kim, Young-Jin ; Nam, Ki-Chan ; Koo, Chul-Mo ;
Journal of the Korean Operations Research and Management Science Society, volume 32, issue 3, 2007, Pages 97~114
IT outsourcing providers has been expanded from a single functional system to the entire IT service to gain sustainable competitiveness. This new trend of IT outsourcing need outsourcing management capability based on a firm's core capacity. Hiring external IT service providers to manage part or all of its information-related services helps a firm focus on its core business and provides better services to its clients, thus obtaining sustainable competitive advantage. This research investigates the major factors that determine the level of a particular firm's success at IT outsourcing. Based on process innovation and core-competency theories, we identify three significant components of a firm's IT outsourcing management method (ITOMM): level of core-competency-based management, maturity of outsourced tasks, and maturity of outsourcing management. Comprehensive data collection was conducted through an outsourcing association. The survey data were analyzed using a structural analysis method. Maturity of outsourced tasks and maturity of outsourcing management were found to affect project performance directly, while level of core-competency-based management only indirectly impacted project performance through its positive impact on the other two ITOMM components.