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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Institute of Industrial Engineers
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Korean Institute of Industrial Engineers
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Volume & Issues
Volume 25, Issue 4 - Dec 1999
Volume 25, Issue 3 - Sep 1999
Volume 25, Issue 2 - Jun 1999
Volume 25, Issue 1 - Mar 1999
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Numerical Stability of Cholesky Factorization in Interior Point Methods for Linear Programming
Seol, Tong-Ryeol ; Seong, Myeong-Ki ; Ahn, Jae-Geun ; Park, Soon-Dal ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 290~297
In interior point methods for linear programming, we must solve a linear system with a symmetric positive definite matrix at every iteration, and Cholesky factorization is generally used to solve it. Therefore, if Cholesky factorization is not done successfully, many iterations are needed to find the optimal solution or we can not find it. We studied methods for improving the numerical stability of Cholesky factorization and the accuracy of the solution of the linear system.
An Integrated Approach for Loading an Scheduling of a Flexible Manufacturing System
Woo, Sang-Bok ; Kim, Ki-Tae ; Chung, Dae-Yeong ; Park, Jin-Woo ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 298~309
In this study, we attempt to solve the loading and scheduling problems of an FMS in an integrated manner. We propose an integrated approach and its solution methodologies which can fully exploit the flexibility of an FMS effectively and make decisions about tool allocation, machine selection, and job sequencing simultaneously. The proposed approach consists of two main modules : 'schedule generating module' which makes partial schedules and 'tool-allocation checking module' which investigates the feasibility of tool-allocation for unscheduled tasks. Utilizing two interacting modules, we can finally settle the loading and scheduling problems. Experimental results show that in most cases the proposed integrated approach outperforms existing hierarchical approaches in the scheduling performance and the computational time required. In addition to that, the difference between the two approaches tends to increase when the number of part types and the number of alternative machines increase and the tool constraints become tight. To conclude, the experimental results show that the proposed approach is a viable one for solving practical problems.
An Interactive Multi-objective Decision Making Technique for Sequencing Mixed Model Assembly Lines Based on Evolution Programs
Kim, Yeo-Keun ; Lee, Soo-Yeon ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 310~320
A mixed model assembly line (MMAL) is a special type of production line where a variety of product models similar in product characteristics are assembled. Determining the model sequence is an important problem for the efficient use of MMALs. This paper considers interactive multiobjective decision making problems for MMAL sequencing. Evolution program is employed as an underlying framework. In this study, a way of approximating the linear utility function is first studied. To improve its search efficiency to the solution space preferred by a decision maker, some modifications of a standard evolution program are made: operating several subpopulations instead of a single population and merging two or more subpopulations to a single subpopulation, and using a Pareto pool. Extensive computational experiments are carried out to verify the performance of the proposed approach. The computational results show that our approach is promising in solution quality.
A Modification and Performance Analysis of Movement-Based Registration in Mobile Communication Network
Kim, K.S. ; Baek, J.H. ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 321~329
An efficient location management for mobile stations plays an important role in mobile communication network. This paper studies a movement-based registration(MBR) method with a selective paging scheme. In the movement-based registration method, a mobile station performs a location registration when the number of cell boundary crossings since the last registration equals to the given movement threshold. In the selective paging scheme, the network first partitions the location area of the called mobile station into a number of subareas and then pages each subarea one after another until the MS is found. To reduce the paging and registration load, we propose a modified MBR(MMBR) method in the aspect of minimization of signaling traffic on radio channels. First, we propose a new establishment of the paging area to reduce the paging load on radio channels and then analyze its effects. Next, we propose the MMBR to reduce the registration load. Numerical results show that our proposed movement-based registration provides the better performance compared with the conventional method.
The Comparison of Sensitivity of Numerical Parameters for Quantification of Electromyographic (EMG) Signal
Kim, Jung-Yong ; Jung, Myung-Chul ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 330~335
The goal of the study is to determine the most sensitive parameter to represent the degree of muscle force and fatigue. Various numerical parameters such as the first coefficient of Autoregressive (AR) Model, Root Mean Square (RMS), Zero Crossing Rate (ZCR), Mean Power Frequency (MPF), Median Frequency (MF) were tested in this study. Ten healthy male subjects participated in the experiment. They were asked to extend their trunk by using the right and left erector spinae muscles during a sustained isometric contraction for twenty seconds. The force levels were 15%, 30%, 45%, 60%, and 75% of Maximal Voluntary Contraction (MVC), and the order of trials was randomized. The results showed that RMS was the best parameter to measure the force level of the muscle, and that the first coefficient of AR model was relatively sensitive parameter for the fatigue measurement at less than 60% MVC condition. At the 75% MVC, however, both MPF and the first coefficient of AR Model showed the best performance in quantification of muscle fatigue. Therefore, the sensitivity of measurement can be improved by properly selecting the parameter based upon the level of force during a sustained isometric condition.
Determination of Optimum Process Mean and Screening Limits for Production Processes with Multi - Decision Alternatives
Hong, Sung-Hoon ; Kwon, Hyuck-Moo ; Kim, Sang-Boo ; Lee, Min-Koo ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 336~341
The problem of jointly determining the optimum process mean and screening limits for each market is considered in situations where there are several markets with different price/cost structures. The quality characteristic is assumed to be a normal distribution with unknown mean and known variance. A quadratic loss function is utilized for developing the economic model. Methods of finding the optimum process mean and screening limits are presented and a numerical example is given.
Two Location Algorithm with Call Information in Mobile Communication Networks
Jang, Hee-Seon ; Cho, Kee-Seong ; Hwang, Hark ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 342~350
Two location algorithm (TLA) considers two location areas (LAs) to track the location of a mobile station (MS). The TLA significantly outperforms the single location algorithm when the call-to-mobility ratio (CMR) is low (i.e., the user moves more frequently than to receive calls). However, because of the paging cost for the users moving back to the previously visited LA, the performance of the TLA degrades when the CMR is high. To reduce those paging cost, we propose the new algorithm called TLA with call information (TLAC). In TLAC, we use the location information of the MS within the setup message when the MS originates a call in the previously visited LA. Through the setup message, the system can know the exact location of the MS without the additional location registration operation, and the paging cost for the arriving calls in the visited LA can be reduced. An analytical model is proposed to compare the TLAC and previous TLA protocol. Our study indicates that the TLAC always guarantees better performance than the TLA. We also observe that the TLAC is much better than the TLA when the CMR is high.
A New Approach to Performance Evaluation of Cellular Systems Considering Mixed Platforms Environment
Yeo, Kun-Min ; Ryu, Ji-Hyun ; Jun, Chi-Hyuck ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 351~359
We present a new approach to the analysis of mobile cellular communication systems under the environment of mixed platforms adopting a guard channel scheme. We assume general cell residence time distributions according to platform-types. Our system model is based on a heterogeneous M/G/c loss system with customer-dependent guard channels, where heterogeneous customers with different service time distributions have different numbers of their own guard channels. We develop the general formula of steady state probabilities for the heterogeneous M/G/c loss system with customer-dependent guard channels. The mean channel occupancy times of new and handoff calls are rigorously derived under a general setting. Finally, our numerical results show that the blocking probability and the forced termination probability are sensitive to the cell residence time distributions.
A Genetic Algorithm for Scheduling Sequence-Dependant Jobs on Parallel Identical Machines
Lee, Moon-Kyu ; Lee, Seung-Joo ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 360~368
We consider the problem of scheduling n jobs with sequence-dependent processing times on a set of parallel-identical machines. The processing time of each job consists of a pure processing time and a sequence-dependent setup time. The objective is to maximize the total remaining machine available time which can be used for other tasks. For the problem, a hybrid genetic algorithm is proposed. The algorithm combines a genetic algorithm for global search and a heuristic for local optimization to improve the speed of evolution convergence. The genetic operators are developed such that parallel machines can be handled in an efficient and effective way. For local optimization, the adjacent pairwise interchange method is used. The proposed hybrid genetic algorithm is compared with two heuristics, the nearest setup time method and the maximum penalty method. Computational results for a series of randomly generated problems demonstrate that the proposed algorithm outperforms the two heuristics.
A Real-time Mixed Scheduling Algorithm in Flexible Manufacturing System
Ro, In-Kyu ; Cho, Chull-Hyung ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 369~381
Recently, the researches of real-time scheduling that manage flexibly system movement are being progressed by using simulation. But because the existing researches are focused on state change of whole system and selected dispatching with real-time, it could not reflect the state changes of each work center accurately, Therefore, the main core of this paper is to examine the state of workcenter, to select the optimal dispatching dynamically through simulation, and to present the algorithm that can manage actively on state of workcenter. Also, performance measure was used the mean tardiness and mean flow time that are used existing researches.
Development of the Revised Self-Organizing Neural Network for Robot Manipulator Control
Koo, Tae-Hoon ; Rhee, Jong-Tae ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 382~392
Industrial robots have increased in both the number and applications in today's material handling systems. However, traditional approaches to robot controling have had limited success in complicated environment, especially for real time applications. One of the main reasons for this is that most traditional methods use a set of kinematic equations to figure out the physical environment of the robot. In this paper, a neural network model to solve robot manipulator's inverse kinematics problem is suggested. It is composed of two Self-Organizing Feature Maps by which the workspace of robot environment and the joint space of robot manipulator is inter-linked to enable the learning of the inverse kinematic relationship between workspace and joint space. The proposed model has been simulated with two robot manipulators, one, consisting of 2 links in 2-dimensional workspace and the other, consisting of 3 links in 2-dimensional workspace, and the performance has been tested by accuracy of the manipulator's positioning and the response time.
A Two-Segment Trunk Model for Reach Prediction
Jung, Eui-S. ; Lim, Sung-Hyun ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 393~403
In this research, a reach posture prediction based on a two-segment trunk model was made. Recently, reach posture prediction models have used inverse kinematics to provide a single posture that a person naturally takes, with a single segment trunk model that had some shortcomings. A two-segment trunk model was first developed with two links; pelvis link and lumbar-thoracic link. The former refers to the link from the hip joint to L5/S1 joint while the latter does the link from L5/S1 to the shoulder joint. Second, a reach prediction model was developed using the two-segment trunk model. As a result, more reliable equations for two-segment trunk motion were obtained, and the lean direction which refers to the movement direction of the trunk was not found to have a significant effect on the two-segment trunk motion. The results also showed that the hip joint is more preferred over L5/S1 to serve as a reference point for trunk models and the reach prediction model being developed predicted the real posture accurately.
Overflow Probability Analysis and Bandwidth Allocation for Traffic Regulated by Dual Leaky Bucket
Yoon, Y.H. ; Lie, C.H. ; Hong, J.S. ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 3, 1999, Pages 404~410
A scheme of more exact overflow probability analysis is proposed for traffic regulated by dual leaky bucket. To each regulated traffic stream is allocated bandwidth and buffer independent of other traffic stream and overflow occurs when total bandwidth or buffer allocated to each traffic exceed link capacity or physical buffer size. Ratio of buffer and bandwidth allocated to each traffic stream is assumed to be constant, and this ratio is larger than the ratio of physical buffer and bandwidth due to buffer sharing effect. Numerical experiments show that this sharing effect have significant influence on overflow probability and effective bandwidth.