• 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.

• Industrial Engineering and Management Systems
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• v.14 no.1
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• pp.1-10
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• 2015

In this paper, we consider multi-item inventory management. When managing a multi-item inventory, we coordinate replenishment orders of items supplied by the same supplier. The associated problem is called the joint replenishment problem (JRP). One often-used approach to the JRP is to apply a can-order policy. Under a can-order policy, some items are re-ordered when their inventory level drops to or below their re-order level, and any other item with an inventory level at or below its can-order level can be included in this order. In the present paper, we propose a method for finding the optimal parameter of a can-order policy, the can-order level, for each item in a lost-sales model. The main objectives in our model are minimizing the number of ordering, inventory, and shortage (i.e., lost-sales) respectively, compared with the conventional JRP, in which the objective is to minimize total cost. In order to solve this multi-objective optimization problem, we apply a genetic algorithm. In a numerical experiment using actual shipment data, we simulate the proposed model and compare the results with those of other methods.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.135-146
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• 1997

This paper describes fault diagnosis method in complex system with hierachical structure similar to human body structure. Complex system is divided into unit, item and component. For diagnosing this hierarchical complex system, it is necessary to implement special neural network. Fault diagnosis system can forecast faults in a system and decide from current machine state signal information. Comparing with other diagnosis system for single fault, the developed system deals with multiple fault diagnosis comprising Hierarchical Neural Network(HNN). HNN consists of four level neural network, first level for item fault symptom classification, second level for item fault diagnosis, third level for component symptom classification, forth level for component fault diagnosis. UNIX IPC(Inter Process Communication) is used for implementing HNN wiht multitasking and message transfer between processes in SUN workstation with X-Windows(Motif). We tested HNN at four units, seven items per unit, seven components per item in a complex system. Each one neural newtork operate as a separate process in HNN. The message queue take charge of information exdhange and cooperation between each neural network.

• Journal of the Korean Society of Systems Engineering
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• v.12 no.2
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• pp.47-57
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• 2016

As the inventory costs of repairable items in military logistics continue to increase, many studies for optimal inventory level of these items are being carried out in advanced countries, including the US, to reduce these costs. Research on inventory level optimization for repairable items aimed to achieve the availability goal of a system with a MIME(Multi Indenture Multi Echelon) repair policy structure first began with Sherbrooke's METRIC and developed into various types. This research is to analyze and compare recent V-METRIC related studies to search for another variation in this field. This paper mainly looks at how to determine optimum inventory level for each repairable item to achieve a specific availability target within a limited budget, and also how to minimize inventory cost while achieving its availability target by determining optimal inventory level of each repairable item.

• Journal of Korean Academy of Nursing
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• v.22 no.4
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• pp.620-635
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• 1992

This study identified correlations between perceived family support and hopelessness in patients admitted to Neuro - surgical Intensive Care Units. The purpose was to enhance theoretical understanding of the relationships of these two variables. The subjects of this study were 51 patients admitted to N-lCU, at three general hospitals in Seoul. Data were collected by researcher in structured interviews from Aug. 12 to Oct. 13, 1992. The research tools were parts of the Moos Family Environment Scale and the Beck Hopelessness Scale. The general characteristic data were analyzed for frequency and percentage ; the hypothesis was tested by the pearson product Moment Correlation Coefficient. After normality tests by using Kolmogorov - Sminorvtest, and T- test, ANOVA and Mann-Whitney U test, Kruskal -Wallis test were used on the Family Support and the Hopelessness about general charcteristics. The results of the above analysis were as follows 1) The average family support score for the group was 63.61 (tool average 51) and item average was 3.74 (tool item average 3) : the family support score of this sample was higher than average. The average family cohesion score of family support was 35.25 (tool average 27) and item average was 3.91 (tool item average 3). The average family expression score of family support was 28.35 (tool average 24) and item average was 3.57 (tool average 3). In this sample, perceived family expression was lower than family cohesion. 2) The average hopelessness score was 45.88 (tool average 60) and item average was 2.29 (tool item average 3) : the hopelessness score of this sample was low in comparison to the average. 3) The hypothesis in this study was supported. The main hypothesis that the higher the perceived family support level, the lower the level Of the hopelessness, was Supported (r＝-.3869 p＝.003). The sub-hypothesis that the higher the perceived family cohesion level, the lower the level of hopelessness, was supported(r＝-.3688 p＝.004). The sub-hypothesis that the higher the perceived family expression level, the lower the level of hopelessness, was supported (r＝-.3068 p＝.014). 4) General characteristics of the objects related to family support were ‘economic status’(p＝.025) and ‘helping person’(P＝.044) : the higher the economic status, the greater the family support. When the patient identified the helping person as a spouse, family support was rated more highly. The only general characteristic related to family cohesion was ‘helping person’(p＝.041). No general characteristics were related to family expression. 5) The one general characteristic related to hopelessness was ‘education’(p＝.002) : the higher their education, the lower their hopelessness. For these ICU patients, were related perceived family support and hopelessness, and family expression level was low in comparison to family cohesion level. The perceived family support of these seriously ill patients in situational crisis may have influenced the patient's emotional reaction of hopelessness. This study concluded that nurses in the ICU confirm the family support of the patient, and involve the family as the most intimate support systems in the care of the patient to help reduce the patient's hopelessness.

• Journal of Gifted/Talented Education
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• v.12 no.4
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• pp.26-44
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• 2002

We have developed a tool and solution to test creativity level for science field. This test tool was considered 7 creativity elements. In development process, it was verified for contents validity, clarity of the item etc. The test developed in this study was analyzed item analysis after applying for 332 middle school students. As a results of item analysis, it showed meaningful(validity: 92%, item difficulty: $42%{\sim}73%$, reliability: 0.84, item discriminating power: $0.22{\sim}0.70$)over the level of a standard basis. This means that the test tool was useful in the test process of creativity level for science.

• IE interfaces
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• v.14 no.3
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• pp.286-295
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• 2001

This paper addresses the problem of determining the proper level of concurrent spare parts(CSP) for a system consisting of multi-item parts under an available budget constraint. Initial provisioning of spare parts plays a major role in the acquisition of a new equipment system. Therefore, the proper level of spare parts should be on hand to maintain the availability of the system. This paper proposes a new CSP model and solution procedure that determines the proper level of spare parts satisfying the item priority and simultaneously available budget constraint.

• Journal of The Korean Association For Science Education
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• v.16 no.3
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• pp.314-328
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• 1996

This study investigated the literature about science process skills' evaluation to analyse transition of evaluation objectives before and after a Scholastic Ability Test for College Entrance. In the literature survey the researcher established a 3 dimensional science assessment framework with X axis as science concept, Y axis as science process skills and Z axis as problem context. In order to analysis and compare each items the researcher selected 210 items from the 1st to the 7th trials and 138 items from the 1st to 4th Scholastic Ability Test for College Entrance and sampled 2873 science achievement test items from 10 high schools. In accordance with this taxonomy the researcher analysed and compared science process skills item forms. The following results were drawn : The items were evenly distributed in all the four areas(Earth Science, Biology, Physics and Chemistry) of the science concept domain, but they were heavily concentrated on data analysis and drawing a conclusion in science process domain. In the domain of problem context school context was the majority. In spite of distribution like this the ratio on science process skills measurement items and science achievement test items was increased after the Scholastic Ability Test for College Entrance was given. Also the ratio on item expression type was increased. Item form was almost 5 options selection type in the national level test. Although there were 4 options selection type, 5 options selection type, short answer type, essay type in school level test, rising from 33.1% to 65.5% on 5 options selection type is exhibited. This study showed that the school level item form was better various than the nation level. This point like this is the evidence for the improvement toward the science process skills test and influenced by Scholastic Ability Test for College Entrance. The ratio on the item which joined with the 3 axes had a mean of 99.3% in nation level test and mean 44.9% in school achievement test level. But the ratio in the school achievement test level increased after the Scholastic Ability Test for College Entrance was given. In view of this study we must furthermore study the item types which can evaluate valjdately science process skill's five stage each and evaluation method by the high school students' problem solving patterns and features in scientific inquiry on all science process skills elements.

• Physical Therapy Korea
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• v.17 no.2
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• pp.51-59
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• 2010

The Functional Independence Measure (FIM) is widely used to determine the dependency of activity of daily living in rehabilitation patients. The purposes of this study were to evaluate the unidimentionality of the FIM physical items and to analyze the validity of cross-functional levels in stroke survivors in Korea. Thirteen physical items of FIM were rated according to an ordinal scale of a 7-level classification. Two hundred and seventy-nine patients participated in the study (age range 18~92 years and 57% male). Six items-eating, bladder control, bowel control, transfer to and from the bed/wheelchair, transfer to and from the toilet, and bathing-showed misfits with the Rasch model. The most difficult item was 'bathing', the easiest item was 'bowel control'. Although there were several differences within functional levels, the hierarchical order of item measures was rather similar. 'Bathing' was the most difficult in high level patients (above 60), however 'stairs' was most difficult in the middle level (41~60) group. In the low level group (below 40), 'toileting' was the most difficult. In conclusion, the present study has shown several differences of item difficulty among functional levels. This result will be useful in planning interventions, and developing rehabilitation programs for stroke survivors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.1
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• pp.89-95
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• 2006

Planning distributed manufacturing logistics is one of main issues in supply chain management. This paper proposes a hybrid heuristic approach for the Multi-Level, multi-item Capacitated Lot Sizing Problem (MLCLSP) in supply chain network. MLCLSP corresponds to a mixed integer programming (MIP) problem. With integer variable solutions determined by heuristic search, this MIP problem becomes linear program (LP). By repeatedly solving the relaxed MIP problems with a heuristic search method in a hybrid manner, this proposed approach allocates finite manufacturing resources fur each distributed facilities and generates feasible production plans. Meta heuristic search algorithm is presented to solve the MIP problems. The experimental test evaluates the computational performance under a variety of problem scenarios.