• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.1
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• pp.42-48
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• 2002

This paper addresses the necessity of integration between buyer and suppliers for effective implementation of Just-In-Time purchasing in a multi-item environment. An integrated inventory model of facilitating multiple shipments in small lots is developed. Also, an iterative solution procedure is developed to simultaneously find the order(contract) interval for each item and number of shipments between buyer and suppliers. We show by example that when the integrated policy is adopted by both buyer and suppliers in a cooperative manner, both parties can benefit.

• International Journal of Reliability and Applications
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• v.17 no.1
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• pp.51-63
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• 2016

Stress function of ball bearing is function of multiple stochastic factors and this system is so complex that analytical expression for reliability is difficult to obtain. To address this pressing problem, in this article, we have made an attempt to approximate system reliability of this important item based on reliability bounds under the stress strength setup. This article also provides level of error of this item. Numerical analysis has been adopted to show the closeness between the upper and lower bounds of this item.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.15 no.26
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• pp.173-179
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• 1992

This paper is concerned with preventive maintenance model for the items whose failures are dependent on their wear level. The previous maintenance models have used time as their decision variable, but it is not appropriate for the case which have wear dependent processes for their failures. In this paper, we consider an operating item which is under periodic review and which is subject to degradation. The scheduled maintenance (overhaul ) is based on the level of item degradation rather time. A functional equation for the total expected cost over an infinite horizon period is formulated and solved.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.211-214
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• 2003

In this paper, we intend to find user's TV program choosing pattern and, recommend programs that he/she wants. So we suggest item dependency map which express relation between chosen program. Using an algorithm that we suggest, we can recommend an program, which a user has not saw yet but maybe is likely to interested in. Item dependency map is used as patterns for association in hopfield network so we can extract users global program choosing pattern only using users partial information. Hopfield network can extract global information from sub-information. Our algorithm can predict user's inclination and recommend an user necessary information.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.211-213
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• 2003

본 논문에서는 MPEG-21 통합 멀티미디어 프레임워크에서 이용되는 기본 단위인 디지털 아이템(Digital Item)의 처리 방안에 대해 설명하고, 디지털 아이템 소비 시스템에 대해 논하였다. 현재 MPEG을 중심으로 표준화중인 디지털 아이템 프로세싱(Digital Item Processing; DIP)을 이용한 디지털 아이템 처리는 디지털 아이템에 소비 및 이용에 대한 기능을 부여한다. DUP 에 기반을 둔 디지털 아이템 처리 및 소비 구조의 적용을 위해 교육용 멀티미디어 컨텐츠를 표현하는 디지털 아이템을 구조화하고 디지털 아이템 소비기를 구현하여 구조화된 디지털 아이템 처리 및 소비 시스템의 유효성을 입증하였다.

• Analyses & Alternatives
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• v.5 no.1
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• pp.3-24
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• 2021

This paper introduces a multilevel item-response-theory (IRT) model as a unifying model for hypothesis testing using legislative voting data. This paper shows that a probit or logit model is a special type of multilevel IRT model. In particular, it is demonstrated that, when a probit or logit model is applied to multiple votes, it makes unrealistic assumptions and produces incorrect coefficient estimates. The advantages of a multilevel IRT model over a probit or logit model are illustrated with a Monte Carlo experiment and an example from the U.S. House. Finally, this paper provides a practical guide to fitting this model to legislative voting data.

• English Language & Literature Teaching
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• v.18 no.1
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• pp.171-195
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• 2012

While noticing that there is insufficient interest in the assessment of EFL learners' vocabulary levels or sizes, the researchers developed two tests identical in form (Forms A and B) to assess the lexical knowledge of Korean university learners at the $1^{st}{\sim}10^{th}$ 1,000 word bands by adapting a pre-established vocabulary levels test (VLT). Of equal concern was to investigate if the VLT was equally a valid and reliable instrument to be used on measuring the lexical knowledge of EFL learners. The participants were 804 university freshmen enrolled in a General Education English Course from four different colleges. The learners were asked to respond to either Form A or B. While scores generally fell towards the lower frequency bands, multiple regression found the Korean College Scholastic Ability Test (CSAT) to be a significant variable for predicting the learners' vocabulary sizes. From a methodological perspective, however, noticeable differences between Forms A and B could be found with item response theory analysis. The findings of the study provide suggestions on how future VLT for testing EFL learners may have to be redesigned.

• Korean Journal of Child Studies
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• v.5
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• pp.53-64
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• 1984

The purpose of this research was to supplement the preceding study and to examine the feasibility of standardizing the Bayley Scales of Infant Development (BSID) for Korean infants. The subjects of this research were 93 healthy infants at 1-12 months of age living in Seoul. Seventy were the same infants as the subjects of the preceding research. Statistical analysis of the results was done by Item analysis and scalogram analysis using Green's method. The scalability of the BSID for Korean infants was .78 on the mental scale and .8l on the motor scale. Item order by counting positive responses was slightly different from the original BSID item order. On the feasibility of standardization of the BSID in Korea, the results showed that: 1) The BSID is scalable for Korean infant development, and 2) The BSID needs correction in item rank order.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.16 no.27
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• pp.21-25
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• 1993

This article is concerned with cost analysis in stepdown warranty policy. The repair of item is divided into two policies. First, perfect repair can be considered that the failurerate is the same as new item. Second, minimal repair is shown that the failurerate is the same as just before the item failure In this paper, the minimal repair model is introduced. And it is assumed that manufacturers repair the item failure within the warranty periodn. But warranty period is not renewed at all. At this point the warranty cost is analyzed in manufacturer's and customer's point of view.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.2
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• pp.46-52
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• 2005

In this paper, we present a temporal association rule based on item time intervals. A temporal association rule is an association rule that holds specific time intervals. If we consider itemset in the frequently purchased period, we can discover more significant itemset satisfying minimum support. Because the previous study did not consider the time interval between purchased item, it could find itemset that did not satisfy the minimum support in case some item was frequently purchased in a specific period and rarely or not purchased in other period. Our approach uses interval support which is counted by period with support and confidence in the association rule to discovery large itemset.