• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.3
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• pp.91-105
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• 2011

In this paper, we analyze a logistic system involving a supplier who produces and delivers multiple types of items and a buyer who receives and sells the products to end customers. The buyer controls the inventory level by replenishing each product item up to a given order-up-to-level to cope with stochastic demand of end customers. In response to the buyer's order, the supplier produces or outsources the ordered item and delivers them at the start of each period. For the system described above, a mathematical model for a single type of item was developed from the buyer's perspective. Based on the model, an efficient method to find the cycle length and safety factor which correspond to a local minimum solution is proposed. This single product model was extended to cover a multiple item situation. From the model, algorithms to decide the base cycle length and order interval of each item were proposed. The results of the computational experiment show that the algorithms were able to determine the global optimum solution for all tested cases within a reasonable amount of time.

• Journal of the Korean association of regional geographers
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• v.11 no.5
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• pp.474-487
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• 2005

This paper aims to provide empirical evidence required to describe the level of achievement by analyzing students' item response in NAEP implemented in the United States in 2001. The geography assessment in the NAEP is aimed to test students of 4th, 8th, and 12th grades, and consists of content dimension and cognitive dimension, The former includes 'space and place' 'environment and society' and 'spatial dynamics and connections,' and the latter includes 'knowing' 'understanding' and 'applying,' The level of achievement is defined as three levels for each grade: Basic, Proficient, and Advanced. In this paper, descriptions of achievement is derived inductively from an analysis of student's responses to the items which were selected by using item-mapping method. As a result, there is a great difference between the level of achievement derived empirically from students' response and the level of achievement designed principally suggested by the expert committee. The former could have a contribution to the improvement in geography curriculum.

• Korean Journal of Comparative Education
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• v.28 no.5
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• pp.1-19
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• 2018

The purpose of educational assessments such as the Trends in International Mathematics and Science Study (TIMSS) is to compare groups such as countries. When the unit of measurement is above the student level, group-level diagnostic assessment based on multilevel item response theory (ML-IRT) can be considered just as cognitive diagnosis models are developed from item response theory. This study suggests an ML-IRT-based group-level diagnostic assessment model by modifying an item feature model by Park and bolt (2008). The model is illustrated on the recently released TIMSS 2015 Grade 8 mathematics assessment. The results provide skill profiles for the studied countries and the nine cognitive attributes; that is, the attribute effects can be compared across the countries and also across the attributes. By controlling unexplained variance, the suggested model may provide more reliable and more informative group-level comparisons. The results are interpreted using an example. Limitations and directions for future research are also discussed.

• Journal of the Korea Safety Management & Science
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• v.8 no.2
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• pp.115-128
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• 2006

The study analyzes those relations of customer service level of each sales branch, level of cooperations among branches, and overall system-wide service level for an item. Under the continuous review method, each sales branch places an order to the outside supplier, and the each branch receives the order quantity after elapsing a certain lead time. Under these circumstances, those branches with stockout condition may be supplied by other branches with keeping stocks to cover the shortages. This policy generally increases the system-wide customer service level for an item throughout cooperations for the safety plan among branches. Therefore, in the context of inventory policy, the decision rules to determine the proper branch levels of service and cooperation levels of service are important goals in terms of attaining desired system-wide service level. This research has suggested the method and procedure to reach above goals.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.3
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• pp.25-35
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• 1993

Economic screening procedures using a correlated variable are proposed to assure that the proportion of conforming items is above a desired level after screening. It is assumed that the performance variable and the screening variable are jointly normally distributed. Two screening procedures are considered. In the first screening procedure, all of the items are inspected on the screening variable. If an item fails to meet the screening specifications, it is rejected and excluded from shipment without inspection of the performance variable. In the second screening procedure, the item which fails to meet the screening specifications is inspected on the performance variable. If the value of the performance variable is within specifications the item is accepted, and the item is rejected otherwise. Cost models are constructed which involve cast from an accepted nonconforming item, cost from a rejected item, and quality inspection cost. Methods of finding optimal cutoff value on a screening variable are presented and numerical examples are given.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.10 no.16
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• pp.129-132
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• 1987

Multi-item inventory problems can be well characterized by the nature of interaction of the quantities and timing. This interaction may be due to the effect of certain combination of orders. It is that the set-up cost of ordering individual items can be saved by jointly ordering at a time. This study finds a decision criteria of optimum inventory policy through the comparisons of individual multi-item order policy(IMP), joint multi-item order policy(JMP), augmented multi-item order policy(AMP) in cost ratio. Subsequently we assume that there exists a unique optimum order level corresponding to an optimum reorder range for the augmented multi-item order, at which a cost saying is maximum.

• Journal of the Korean Society of Clothing and Textiles
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• v.15 no.4 s.40
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• pp.405-416
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• 1991

This paper examined the risks perceived by consumers in apparel buying situation by 1) measuring the contents and perception level of risk, 2) categorizing each risk into meaningful factors (risk types), 3) analyzing the relationships between risk types and consumers' demo-graphic variables. 224 respondents deliberately selected to include each level of S demographic variables were contacted with 37-item question3.ire. Factor analysis showed that 32-item perceived risk could be categorized into 6 risk types: psychological. social, economic, time/convenience loss, fashionability loss, performance risk. Psychological risk were perceived highest in terms of perception level while social and performance risk showed relatively low perception level. 4 of 5 demographic variables including sex, education level, income, occupa-tion showed partial relationship with each risk type after ANOVA and Duncan test. Sex had the greatest influence on risk perception level and each age level (20's, 30's, 40's) showed different risk structure.

• Journal of The Korean Association For Science Education
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• v.11 no.2
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• pp.161-178
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• 1991

This study was designed to investigate the effect of test anxiety, intelligence, and item arrangement order on test performance in Earth Science. The main purposes in this study were to investigate (1) (2) (3) (4) on test performance.: (1) the effect of test anxiety components on test performance in Earth Science. (2) the effect of item arrangement order on test performance in Earth Science. (3) the effect of test anxiety This study was designed to investigate the effect of test anxiety, intelligence, and item arrangement order on test performance in Earth Science. The main purposes in this study were to investigate (1) (2) (3) (4) on test performance.: (1) the effect of test anxiety components on test performance in Earth Science. (2) the effect of item arrangement order on test performance in Earth Science. (3) the effect of test anxiety components on test performance in Earth Science according to learner's intelligence levels. (4) test effect of item arrangement order on learner's intelligence. The hypothesis was that there is difference among test achievements scores according to (1) test anxiety-worry levels. (2) item arrangement orders. (3) item arrangement orders on test anxiety-worry levels. (4) test anxiety-worry levels on intelligence levels. (5) test anxiety-emotionality levels. (6) item arrangement orders on test anxiety-emotionality levels. (7) test anxiety-emotionality levels on intelligence levels. (8) item arrangement orders on intelligence levels. The test items selected for this study were derived from the text Science (part 1) first grade of high school. The subjects of this study were 164 of high school first grade boy students in Pusan. They were assigned to one of the three groups, according to test anxiety levels.: (1) upper 25% of total subjects designated to high group (2) middle 50% (3) low group, lower 25% of total subjects And according to LQ. (1) upper 25% of total subjects designated to high group. (2) middle 50%. (3) low group, lower 25% of total subjects Analysis of variance was used in this study for hypothesis examination. The dependent variable was the achievement scores of Earth Science test and independent variables were test anxiety(worry, emotionality) level, LQ. level, item arrangement orders. The principal findings of the present study are as follows: (1)Test achievement score trend decreases as the test anxiety (worry, emotionality) increases although the result is not statistically significant. (2)There is no significant difference among test achievement scores according to item arrangement orders. (3)The higher the LQ. is, the more effective test anxiety. And the LQ. has significant interaction effect with test anxiety. (4)There is significant interaction effect between the LQ. levels and itemqr arrangement orders.

• Physical Therapy Korea
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• v.23 no.4
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• pp.71-80
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• 2016

Background: Functional capacity evaluations (FCEs) are designed to systematically assess the capacity to perform work-related tasks and to determine worker's ability to return to the previous job following work-related injuries. These evaluations may be rated either by clinician or worker. There has been a lack of consensus between the two scoring methods. Objects: This study aimed: 1) to confirm if the data are fit to the Rasch rating scale model and 2) to investigate the item-level concordance rate between the ratings of clinician and injured worker of the FCE. Methods: A cross-sectional study was conducted with a sample (n=124) of a rehabilitation program with the Occupational Rehabilitation Data Base for workers with low back pain. The functional capacity evaluation at admission and discharge was administered to clinicians and workers. The data were analyzed using both classical test theory-based Pearson's r and intra-class coefficient followed by item-level analysis with Rasch rating scale model. Results: All items of the FCE, except sitting items rated by clinician at admission and handling items rated by both clinician and worker throughout admission and discharge, were acceptable fit statistics with minor out of ranges for a misfit criterion. This may indicate that the items of the FCE overall fit to the Rasch rating scale model. Few problematic items responding differently to clinician and worker both at admission and discharge were detected with the differential item functioning analysis despite the excellent concordance rate using the two conventional statistics-sitting and handling items at admission and handling item at discharge. Conclusion: The item-level speculations using Rasch analysis of the FCE demonstrate that the ratings of clinician and self ratings of worker were psychometrically acceptable though there was an apparent discrepancy between the raters both at admission and discharge.

• Journal of The Korean Association of Information Education
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• v.5 no.2
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• pp.268-278
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• 2001

This study is design and implementation of diagnosis module using item response theory to assess level of student's knowledge in web-based instruction systems. Item response theory uses responses to items on a test or survey questionnaire to simultaneously locate both the items on the latent trait defined by the set of items while simultaneously scaling each item on the very same dimension. Existing method of measurement in web-based instruction system provided dichromatic learning after to be assess just with the total scores of exam. This measurement has an error that do not consider the level of student's knowledge. Moreover, this method can't perform an exact diagnosis of student knowledge and make student modeling to construct intelligent tutoring system. In this study, we present that design and implement a diagnosis module using item response theory to assess level of student's knowledge in web-based instruction systems