• The Korean Journal of Emergency Medical Services
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• v.28 no.2
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• pp.7-19
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• 2024

Purpose: To adjust item numbers in a national test, this study used item response theory to examine changes in average scores, reliability, difficulty, and discrimination according to the adjustment of item numbers. Methods: We analyzed the dichotomous coding of correct and incorrect answers of 473 examinees in a mock test conducted in 2023. Additionally, as an explanatory pilot study, we used an online questionnaire to survey experts on their perceptions of the appropriate item numbers for each test subject from January 18, 2024, to February 15, 2024. Results: Regarding the item numbers on the national exam, experts preferred to reduce the number of management of emergency patients (33.14±6.09, p<.05) and advanced emergency medical care: subtopics (104.49±11.55, p<.05), and the total number of questions (217.82±20.95, p<.05). In a simulation set in which items with low item fit were removed after fitting a two-parameter item response theory model, reliability was maintained at .910 until the 5th test consisting of 185 questions with little loss of difficulty, discrimination, and average score, and there was no correlation between item numbers and average score. Conclusion: Experts responded that reducing the number of items on the national exam was appropriate. As a result of the item reduction simulation, there was no significant loss in the average score, difficulty, discrimination, or reliability. More reliable results could be obtained if the results were based on a validity analysis and analyzed using actual national exams.

• Research in Mathematical Education
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• v.7 no.3
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• pp.163-189
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• 2003

The purpose of this study is to develop a test, which can be used in creative problem solving ability in mathematics of the mathematically gifted and the regular students. This test tool is composed of three categories; fluency (number of responses), flexibility (number of different kinds of responses), and originality (degree of uniqueness of responses) which are the factors of the creativity. After applying to 462 middle school students, this test was analyzed into item analysis. As a results of item analysis, it turned out to be meaningful (reliability: 0.80, validity: item 1(1.05), item 2(1.10), item 3(0.85), item 4(0.90), item 5(1.08), item difficulty: item 1(-0.22), item 2(-0.41), item 3(0.23), item 4(0.40), item 5(-0.01), item discriminating power: item 1(0.73), item 2(0.73), item 3(0.67), item 4(0.51), item 5(0.56), over the level of a standard basis. This means that the test tool was useful in the test process of creative problem solving ability in mathematics

• Journal of Korea Game Society
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• v.7 no.4
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• pp.125-134
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• 2007

There have been many researches on the characteristics of item trade. However, most researches were done by carrying out a survey and there has been few researches by analyzing the economy in online games. So, this article studied the cause of item trade by looking into the supply and demand of items in online games. The results shows that item trade is taking place mostly among only a few number of gamers who enjoy enchanting and who engage in castle sieges and blood pledge battles. The proportion of item trade by general garners is not so big. And major item providers are gold farms, not garners. Therefore, item trade is mostly carried out by a large number of garners who trade a small amount of sum and by a small number of heavy garners who trade large amount of sum. Understanding this characteristic of item trade would be a good ground for reviewing the policies and social effect regarding item trades.

• Industrial Engineering and Management Systems
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• v.12 no.3
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• pp.172-180
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• 2013

We herein consider a stochastic multi-item inventory management problem in which a warehouse sells multiple items with stochastic demand and periodic replenishment from a supplier. Inventory management requires the timing and amounts of orders to be determined. For inventory replenishment, trucks of finite capacity are available. Most inventory management models consider either a single item or assume that multiple items are ordered independently, and whether there is sufficient space in trucks. The order cost is commonly calculated based on the number of carriers and the usage fees of carriers. In this situation, we can reduce future shipments by supplementing items to an order, even if the item is not scheduled to be ordered. On the other hand, we can reduce the average number of items in storage by reducing the order volume and at the risk of running out of stock. The primary variables of interest in the present research are the average number of items in storage, the stock-out volume, and the number of carriers used. We formulate this problem as a multi-objective optimization problem. In a numerical experiment based on actual shipment data, we consider the item shipping characteristics and simulate the warehouse replenishing items coordinately. The results of the simulation indicate that applying a conventional ordering policy individually will not provide effective inventory management.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.27 no.3
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• pp.1-25
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• 2014

Objective : For activation of study on filed of odontology in Korean medicine academia, we analyzed the trend of articles that published in journals of Korean medicine. Methods : Using search words of odontology, in internet reference sites we collected papers and classified those into three categories like as review article, original article, case report. Observation points of each item are as follows. Inclusive item of papers; publication year, journal, number of authors, disease. Item of review article; subject of paper, Item of original article; number of patients, period of research, remedy. Item of case report; remedy, valuation of criteria, number of cases. Results : The total number of articles searched was 88, consisting of 23 review articles, 46 original articles and 19 case reports. The percentage of 'TMJ diseases' ranked highest(47.7%) in classification by disease. The most reviewed subject was 'Remedy' (16 times). '25 or less' person ranked highest(50%) in the number of patient in original articles. Acupuncture, chuna manual medicine and herbal medicine were mostly applied in case reports. The number of 'one case' reported case reports was highest(52.6%).

• Management Science and Financial Engineering
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• v.19 no.1
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• pp.25-28
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• 2013

Consider the inverse bin-packing number problem. Given a set of items and a prescribed number K of bins, the inverse bin-packing number problem, IBPN for short, is concerned with determining the minimum perturbation to the item-size vector so that all the items can be packed into K bins or less. It is known that this problem is NP-hard (Chung, 2012). In this paper, we investigate some special cases of IBPN that can be solved in polynomial time. We propose an optimal algorithm for solving the IBPN instances with two distinct item sizes and the instances with large items.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.39
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• pp.19-26
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• 1996

A solution procedure to minimize the number of storage carousels has been developed under the carousel throughput rate and total storage capacity requirements. The number of carousels can be reduced by increasing the throughput rate of carousels which depends upon the size of carousels, the storage item allocation to carousels, and the item position assignments in each carousel. Since the problem is very complicated and hard to solve optimally, the following solution procedure to solve the problem hierarchically is proposed: With a given number of carousels, the storage items are allocated to carousels so that the slowest average transaction time among carousels may be minimized, and then the position of each item is assigned in the allocated carousel so that the throughput of the carousel can be maximized.

• The Mathematical Education
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• v.46 no.4
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• pp.407-421
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• 2007

The purpose of this study is to identify the item characteristics that are supposed to affect item difficulty and to estimate the regression equations for predicting item difficulty of mathematics in the College Scholastic Ability Test(CSAT). We selected six variables related to item characteristics based on learning theories: contents, cognitive domain, novelty, item type, number of concepts, and the amount of computation. With data of the CSAT mathematics test administered in 2004-2006, item difficulty was regressed on the six variables, the location of an item, and the item writer's judgment on difficulty. The novelty of an item was found to be a statistically insignificant variable in explaining item difficulty. Four regression equations with different sets of independent variables could explain $70%{\sim}80%$ of the item difficulty variance and were validated as predicting item difficulty of the mock CSAT in 2006.

• The Mathematical Education
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• v.37 no.1
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• pp.1-13
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• 1998

In this paper, we have represented the efficient way how to enumerate the optimal number-right scores to adjust the item difficulty and to improve item discrimination. To estimate the optimal number-right scores in two equivalent math-tests by linear score equating a measurement error model was applied to the true scores observed from a pair of equivalent math-tests assumed to measure same trait. The model specification for true scores which is represented by the bivariate model is a simple regression model to inference the optimal number-right scores and we assume again that the two simple regression lines of raw scores and true scores are independent each other in their error models. We enumerated the difference between mean value of $\chi$＊ and ${\mu}$$\_$$\chi$/ and the difference between the mean value of y＊and a＋b${\mu}$$\_$$\chi$/ by making an inference the estimates from 2 error variable regression model. Furthermore, so as to distinguish from the original score points, the estimated number-right scores y’$\^$*/ as the estimated regression values of true scores with the same coordinate were moved to center points that were composed of such difference values with result of such parallel score moving procedure as above mentioned. We got the asymptotically normal distribution in Figure 5 that was represented as the optimal distribution of the optimal number-right scores so that we could decide the optimal proportion of number-right score in each item. Also by assumption that equivalence of two tests is closely connected to unidimensionality of a student’s ability. we introduce new definition of trait score to evaluate such ability in each item. In this study there are much limitations in getting the real true scores and in analyzing data of the bivariate error model. However, even with these limitations we believe that this study indicates that the estimation of optimal number right scores by using this enumeration procedure could be easily achieved.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.15-23
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• 1998

This paper concerns the problem of determining the spare inventory level for multi-echelon repairable-item inventory system with finite number of operating items. We consider the system which has several bases and a central depot. When an item fails, it is dispatched to a repair facility and, a spare, if available, is plugged in immediately. When the failed item is repaired, it is sent to the base and either is used to fill a backorder or is stored at a spare inventory point. Using queueing network, we develop an algorithm to find the spare inventory level which minimizes the total expected cost and, simultaneously, satisfies a specified minimum fill rate. The results of the algorithm clearly indicate that the algorithm successfully generate output with optimal solution.