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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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A Coevolutionary Algorithm for Balancing and Sequencing Mixed - Model U-Lines
Kim, Yeo-Keun ; Kim, Sun-Jin ; Kim, Jae-Yun ; Kwak, Jai-Seung ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 411~420
A mixed model production line is a production line where a variety of product models are produced. In U-shaped production lines (called U-lines) used in just-in-time production system, the strategy of mixing product models is often used to provide various types of products to customers in time. Line balancing and model sequencing problems are important for an efficient use of mixed model U-lines. Although the two problems are tightly interrelated with each other, prior researches have considered them separately or sequentially. This paper presents a new method using a coevolutionary algorithm that can solve the two problems at the same time. To promote diversity and search efficiency, in this paper the evolutionary system is based on the localized interactions within and between populations. Methods of selecting environmental individuals and evaluating fitness are developed. Efficient genetic representations and operator schemes are also provided. When designing the schemes, we take into account the features specific to the problems. The experimental results demonstrate that the proposed algorithm is superior to existing approaches.
A Simulation Study on Positioning Methods of Idle Vehicles in AGVS
Kim, Jae-Yeon ; Kim, Kap-Hwan ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 421~436
It is discussed how to locate idle vehicles of AGVS considering dynamically changing situation. Several positioning methods are suggested including static positioning, dynamic positioning with time-independent pickup probabilities, dynamic positioning with time-dependent pickup probabilities, and dynamic positioning with a look-ahead capability. These positioning strategies are compared with each other by a simulation experiment.
Identification of Prevailing Risk Attitudes in Various Risk Situations
Kang, Tae-Geon ; Cho, Sung-Ku ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 437~447
Previous researches on risk attitudes or on the typical utility functions have mostly focused on how the risk attitude of decision maker varies when changes are made in one or two lottery reference points such as consequence domain and magnitude of probability under assumed risk situations represented by simple lotteries. It is, however, very difficult to forecast dominant risk attitudes under risk situations which exhibit a complex combination of many reference points. In this study, twelve risk situations which a decision maker may confront in real decision-making situations were formulated by combining in various ways three reference points, that is, magnitude of probability, consequence domain, and magnitude of gain or loss. Then through a questionnaire dominant risk attitudes under every assumed risk situation were investigated, and the general shape of utility function implied by the experimental results were derived. Results of the present study show that none of the three reference points have dominant effect over the others due to complicated interaction between them, and given the twelve risk situations the observed risk attitude widely varies from strong risk taking to strong risk aversion.
Cumulative Sequential Control Charts with Sample Size Bound
Chang, Young-Soon ; Bai, Do-Sun ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 448~458
This paper proposes sequential control charts with an upper bound on sample size. Existing sequential control charts have no restriction on the number of observations at a sampling point. For situations where sampling and testing an item is time-consuming or expensive, sequential control charts may not be directly applied. When the number of observations in a sampling point reaches the upper bound and there is no out-of-control signal, the proposed cumulative sequential control chart defers the decision to the next sampling point of which starting value is the value of the current statistic. Two Markov chains, inner and outer chains, are used to derive the formulas for evaluating the performance of the proposed chart. It is compared with
and cumulative sum control charts with fixed and variable sample sizes. The fast initial response (FIR) feature is studied. Guidelines for the design of the proposed charts are also given.
Design of a New-Concept VDT Workstation Chair for Improving Work Safety
Shin, Jong-Hyun ; Park, Min-Yong ; Kim, Jung-Yong ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 459~465
A new-concept VDT workstation chair with adjustable keyboard/mouse support was proposed to minimize physical discomfort and the risk of cumulative trauma disorders (CTDs) at work sites in this study. First, a three-dimensional human modeling tool
was used to design the new chair satisfying the anthropometric specifications of Korean population. Second, based upon the result of 3-D graphical simulation, a mock-up chair was constructed with an adjustable keyboard/mouse support directly attached to the chair body. Third, muscle fatigue and subjective discomfort were measured to evaluate the newly developed chair. An experiment was conducted to compare the new workstation chair to the traditional computer chair without keyboard/mouse support. Six volunteer subjects participated in six one-hour word-processing sessions with two different chairs and three different postures. Statistical results indicate that the new-concept VDT chair generally improved subjective comfort level and reduced fatigue in finger flexor/extensor and low back muscle. In conclusion, this new VDT workstation chair is expected to reduce physical discomfort and prevent occupational CTD problems in the long run. Implications of the new design and suggestions for the further development are also addressed.
Dynamic Programming Model for Optimal Replacement Policy with Multiple Challengers
Kim, Tae-Hyun ; Kim, Sheung-Kown ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 466~475
A backward Dynamic Programming(DP) model for the optimal facility replacement decision problem during a finite planning horizon is presented. Multiple alternative challengers to a current defender are considered. All facilities are assumed to have finite service lives. The objective of the DP model is to maximize the profit over a finite planning horizon. As for the cost elements, purchasing cost, maintenance costs and repair costs as well as salvage value are considered. The time to failure is assumed to follow a weibull distribution and the maximum likelihood estimation of Weibull parameters is used to evaluate the expected cost of repair. To evaluate the revenue, the rate of operation during a specified period is employed. The cash flow component of each challenger can vary independently according to the time of occurrence and the item can be extended easily. The effects of inflation and the time value of money are considered. The algorithm is illustrated with a numerical example. A MATLAB implementation of the model is used to identify the optimal sequence and timing of the replacement.
Paradigm Shift of Global Market and Pattern of Technology Innovation for Automotive Steel Sheets
Jung, Kyung-Hee ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 476~489
This paper is concerned with the deployment of core technologies for automotive steel sheets, based on the structural change of global market. The main tasks of automotive industry are to ensure the energy consumption, environmental regulations, and driving safety. With social and legal requirements, this study analyzes the market creation processes with technological innovations for hot rolled, cold rolled and galvanized steel sheets during the 20th century. It has been proven that the leading country in the steel industry was also that in the automotive. The purchaser-supplier relations of sheet materials are then patternized in the regional markets of the United States and Japan, who share nearly 50% of market in the world. According to the paradigm shift of globalization, the balance of power in Porter's 5 forces has been moved to the buyers', and both industries pursue Win-Win strategies such as the PNGV(Partnership for a New Generation of Vehicles ) and design-in system with the competition.
Vehicle Routing Problem Using Parallel Genetic Algorithm
Yoo, Yoong-Seok ; Ro, In-Kyu ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 490~499
Vehicle routing problem(VRP) is known to be NP-hard problem, and good heuristic algorithm needs to be developed. To develop a heuristic algorithm for the VRP, this study suggests a parallel genetic algorithm(PGA), which determines each vehicle route in order to minimize the transportation costs. The PGA developed in this study uses two dimensional array chromosomes, which rows represent each vehicle route. The PGA uses new genetic operators. New mutation operator is composed of internal and external operators. internal mutation swaps customer locations within a vehicle routing, and external mutation swaps customer locations between vehicles. Ten problems were solved using this algorithm and showed good results in a relatively short time.
An Optimal Routing for Point to Multipoint Connection Traffics in ATM Networks
Chung, Sung-Jin ; Hong, Sung-Pil ; Chung, Hoo-Sang ; Kim, Ji-Ho ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 500~509
In this paper, we consider an optimal routing problem when point-to-point and point-to-multipoint connection traffics are offered in an ATM network. We propose a mathematical model for cost-minimizing configuration of a logical network for a given ATM-based BISDN. Our model is essentially identical to the previous one proposed by Kim(Kim, 1996) which finds a virtual-path configuration where the relevant gains obtainable from the ATM technology such as the statistical multiplexing gain and the switching/control cost-saving gain are optimally traded-off. Unlike the Kim's model, however, ours explicitly considers the VP's QoS(Quality of Service) for more efficient utilization of bandwidth. The problem is a large-scale, nonlinear, and mixed-integer problem. The proposed algorithm is based on the local linearization of equivalent-capacity functions and the relaxation of link capacity constraints. As a result, the problem can be decomposed into moderate-sized shortest path problems, Steiner arborescence problems, and LPs. This fact renders our algorithm a lot faster than the previous nonlinear programming algorithm while the solution quality is maintained, hence application to large-scale network problems.
Analysis of Incomplete Field Data with Covariates
Oh, Young-Seok ; Choi, In-Su ; Bai, Do-Sun ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 510~516
This paper proposes methods of estimating lifetime distribution from incomplete field data under parametric regression models. Failure-record data-failure times and covariates-reported to the manufacturer can be seriously incomplete for satisfactory inference since only reported failures are recorded. This paper assumes that within-warranty data are reported with probability
) and after-warranty data are reported with Methods of obtaining pseudo and after-warranty data are reported with
). Methods of obtaining pseudo maximum likelihood estimators(PMLEs) are outlined, their asymptotic properties are studied, and specific formulas for Weibull distribution are obtained. Simulation studies are perfumed to investigate the effects of follow-up percentage on the PMLEs.
Economic Constant Stress Plans for Accelerated Life Testing
Seo, Sun-Keun ; Kim, Kap-Seok ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 517~526
This paper deals with two economic optimal designs of constant-stress accelerated life test(ALT) where failure distribution follows one of location-scale family, i. e., exponential, Weibull, and lognormal distributions which have been ones of the popular choices of failure distributions. Two optimization criteria to develop ALT plans are the statistical efficiency per unit expected cost which consists of the fixed test cost, cost being proportional to the number of test units, and variable test cost depending on test period and stress level, and the expected loss which combines Taguchi's quadratic loss function and expected test cost. Optimum plan determines the low stress level, test units allocated to each stress, and censoring times at two stress levels under Type I censoring. The proposed ALT plans are illustrated with a numerical example and sensitivity analyses are conducted to study effects of pre-estimates of design parameters.
On the Optimal D-Policy for the M/G/1 Queue
Chae, Kyung-Chul ; Park, Yon-Il ;
Journal of Korean Institute of Industrial Engineers, volume 25, issue 4, 1999, Pages 527~531
Instead of using the expected unfinished work, we use the expected number of customers in the system for finding the optimal D-policy for the M/G/1 queue in order to make it consistent with other control policies such as N-policy and T-policy.