• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.189-194
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• 2002

As a environment of SCM is issued recently, many enterprises are concerned about inventory control for an efficiency of operation and reliablity. The goal of them is to match up to improving of facilities and redoing of inventory cost. To put an efficiency in the operation rate of facilites, A moderate provision of spare parts for that would come into a matter. This study designs two-echelon spare parts distribution system and sees over the relationship between operating rate and inventories of spare parts. and then it determines fitting inventories and investment cost considering an operating rate.

• IE interfaces
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• v.21 no.4
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• pp.444-455
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• 2008

In the present manufacturing environment, the appropriate decision making strategy has a significance and it should count on the fast-changing demand of customers. This research derives the optimal levels of the decision variables affecting the inventory related performance in multi-stage supply chain by using simulation and genetic algorithm. Simulation model helps analyze the customer service level of the supply chain computationally and the genetic algorithm searches the optimal solutions by interaction with the simulation model. Our experiments show that the integration approach of the genetic algorithm with a simulation model is effective in finding the solutions that achieve predefined target service levels.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.7
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• pp.750-755
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• 2014

Product shortage which causes backordering and/or lost sales cost is very popular in chemical industries, especially in commodity polymer business. This study deals with backordering cost in the supply chain optimization model under the framework of process-inventory network. Classical economic order quantity model with backordering cost suggested optimal time delay and lot size of the final product delivery. Backordering can be compensated by advancing production/transportation of it or purchasing substitute product from third party as well as product delivery delay in supply chain network. Optimal solutions considering all means to recover shortage are more complicated than the classical one. We found three different solutions depending on parametric range and variable bounds. Optimal capacity of production/transportation processes associated with the product in backordering can be different from that when the product is not in backordering. The product shipping cycle time computed in this study was smaller than that optimized by the classical EOQ model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.1
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• pp.1-10
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• 2009

Inventory Management has become a very important issue in supply chain management, because inventories may be used as a means to accomplish the certain strategic goals in company decisions. RFID(radio frequency identification) technology is used to help manage inventories. It is known that the ideal control of inventories is to replenish item by item. This paper points out several misinterpretations from the Wal-mart report presented in '07 Seoul Forum and suggests the new direction of RFID application. In this paper we consider RFID as not 'identification technology' but 'information technology.' The 'RF-Kanban' suggested here is adopted from the'Kanban'concept of TPS(Toyota Production System). The RF-Kanban system shows the easier control for replenishing various items in boxes. Lots of inventories can be reduced through RF-Kanban System. This work develops the protocol of RF-Kanban and introduces the case study for easier understanding.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1999.04a
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• pp.426-426
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• 1999

;There are many sources of uncertainty in a typical production and inventory system. There is uncertainty as to how many items customers will demand during the next day, week, month, or year. There is uncertainty about delivery times of the product. Uncertainty exacts a toll from management in a variety of ways. A spurt in a demand or a delay in production may lead to stockouts, with the potential for lost revenue and customer dissatisfaction. Firms typically hold inventory to provide protection against uncertainty. A cushion of inventory on hand allows management to face unexpected demands or delays in delivery with a reduced chance of incurring a stockout. The proposed strategies are used for the design of a probabilistic inventory system. In the traditional approach to the design of an inventory system, the goal is to find the best setting of various inventory control policy parameters such as the re-order level, review period, order quantity, etc. which would minimize the total inventory cost. The goals of the analysis need to be defined, so that robustness becomes an important design criterion. Moreover, one has to conceptualize and identify appropriate noise variables. There are two main goals for the inventory policy design. One is to minimize the average inventory cost and the stockouts. The other is to the variability for the average inventory cost and the stockouts The total average inventory cost is the sum of three components: the ordering cost, the holding cost, and the shortage costs. The shortage costs include the cost of the lost sales, cost of loss of goodwill, cost of customer dissatisfaction, etc. The noise factors for this design problem are identified to be: the mean demand rate and the mean lead time. Both the demand and the lead time are assumed to be normal random variables. Thus robustness for this inventory system is interpreted as insensitivity of the average inventory cost and the stockout to uncontrollable fluctuations in the mean demand rate and mean lead time. To make this inventory system for robustness, the concept of utility theory will be used. Utility theory is an analytical method for making a decision concerning an action to take, given a set of multiple criteria upon which the decision is to be based. Utility theory is appropriate for design having different scale such as demand rate and lead time since utility theory represents different scale across decision making attributes with zero to one ranks, higher preference modeled with a higher rank. Using utility theory, three design strategies, such as distance strategy, response strategy, and priority-based strategy. for the robust inventory system will be developed.loped.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.6
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• pp.563-568
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• 2013

The purpose of this study is to find the analytic solution for determining the optimal capacity (lot-size) of a batch-storage network to meet the finished product demand under infrequent shutdowns. Batch processes are bound to experience random but infrequent operating time losses. Two common remedies for these failures are duplicating another process or increasing the process and storage capacity, both of which are very costly in modern manufacturing systems. An optimization model minimizing the total cost composed of setup and inventory holding costs as well as the capital costs of constructing processes and storage units is pursued with the framework of a batch-storage network of which flows are susceptible to infrequent shutdowns. The superstructure of the plant consists of a network of serially and/or parallel interlinked batch processes and storage units. The processes transform a set of feedstock materials into another set of products with constant conversion factors.A novel production and inventory analysis method, the PSW (Periodic Square Wave) model, is applied. The advantage of the PSW model stems from the fact it provides a set of simple analytic solutions in spite of a realistic description of the material flow between processes and storage units. The resulting simple analytic solution can greatly enhance a proper and quick investment decision at the early plant design stagewhen confronted with diverse economic situations.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.702-707
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• 2006

There have been certain extent of material inventory in construction site because of difficulties in ordering by small quantity, strategy of securing future requirements and prevention of delay. However, carrying these inventory entails a financial cost called inventory holding cost and decrease construction productivity, so proper inventory management in construction industry is important for construction efficiency and cost reduction. This study tries to find analytical method of inventory management. It includes ordering decision which decide how much to order and when to order. Setting these strategies including deciding safety inventory, input and ouput variability are able to controled.

• Korean Journal of Child Studies
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• v.15 no.2
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• pp.69-96
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• 1994

The purpose of this study was to develop an inventory for measuring verbal control modes of korean parent. The subjects of this study were 332 children of fifth and sixth grade in elementary schools located in Seoul. Forty seven questions were developed, of which 24 were collected from other previous studies and 23 were newly developed by the researcher and each question was composed of 3 items. The 141 items (47 questions x 3 items) were analyzed by the statistical methods of item analysis, principal factor analysis. The resulting inventories composed of 28 (84 items) and 29 (87 items) questions assess the three types of verbal control modes of both mothers and fathers: imperative control, position-oriented control and person-oriented control. Internal consistency of the scale was high (Cronbach's= .91-.95). Factor validity was also satisfactory (.66-.87).

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.2
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• pp.17-33
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• 1996

Automatic transfer defined as an integrated system with a number of workstations, interstation storage buffers, automatic device and a control system, play a major role in ass production systems. Due to high capital investment needed for an automatic transferline, greater care should be taken in its design so as to maximize the system performance. One may to control the system performance is to control buffer storage. To control the interstation work-in-process inventory, we propose dual limit switches which control the buffer storage with two parameters, R and r. Under the policy, proceding station is forced down when the inventory level in the buffer reaches R until the level falls to r. For the model developed, we analyze the system characteristics and find the optimal control parameters with a serach procedure.

• Journal of the Korean Home Economics Association
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• v.29 no.2
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• pp.77-86
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• 1991

본 연구의 목적은 1) 집단 급식소의 재고 관리 시스템에 관한 자기학습식 Module (Self-instructional Module)을 개발하고, 2) 비동등 통계 실험연구 디자인 (Nonequivalent Control group research design)을 사용하요 자기학습식 재고 관리 시스템 Module의 교육적 효과를 평가하여, 3) 교육기관 및 집단 급식소에서의 교육용 교재로서의 타당성 여부를 검증하고자 함이다. 집단급식소의 재고 관리 시스템에 관한 자기학습식 Module을 개발하기 위해서 현재 미국 전역의 가정대학 내의 식품영양 및 급식경양학과에서 재고 관리에 관련된 교과목을 위하여 채택되어 사용되어지고 있는 주요 교과서들의 내용 분석과 급식경영학 전공 교수 3인의 판단에 기초를 두어 재고관리에 포함되어야 할 내용이 분석되었다. 포함되어져 있는 내용의 목차는 반입(receiving), 저장(storing), 출고(issuing), 재고통제(inventory control), 재고의 자산적 가치(inventory valuation) 및 재고관리 시스템의 자동화(inventory control computer system)등이다. 실험 대상은 Iowa 주립대학에서 급식정보관리 (Foodservice Management Information System) 과목을 수강하였던 88명의 학생이며, 강의를 통해 수업을 받은 통제집단 46명과, 자기 학습식 Module을 사용했던 실험집단 42명으로 구성되었다. 모든 실험 대상에게는 사전검사(Pretest)와 사후검사(posttest)를 실시하였으며 자료의 처리는 SPSS PC Package를 통계법으로 분석하였다. 연구결과는 강의 중심의 통제집단과 자기학습식 Module을 사용했던 실험집단 간의 통제 후 평균 값(posttest adjusted mean score)사이에는 유의적인 차이를 보였으며 (p<0.05), 자기 학습식 Module 그룹에 속해 있던 학생들이 더 높은 통제 후 평균값(adjusted mean score)을 보여 주었다. 그러므로, 이 실험을 통하여, 개발된 집단 급식소 재고관리 시스템에 대한 자기학습식 Module은 학생들에게 재고관리 시스템에 관한 개념과 내용의 습득력을 향상시키는데 있어서 적어도 강의식 교수법과 동일하거나 더나은 교육적 효과를 가져왔다고 판단되었다.