• Journal of the Korea Safety Management & Science
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• v.8 no.3
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• pp.115-123
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• 2006

The main focus of this study is to investigate the performance of a clark-scarf type multi-echelon serial supply chain operating with a base-stock policy and to optimize the inventory levels in the supply chains so as to minimize the systemwide total inventory cost, comprising holding and backorder costs as all the nodes in the supply chain. The source of supply of raw materials to the most upstream node, namely supplier, is assumed to have an infinite raw material availability. Retailer faces random customer demand, which is assumed to be stationary and normally distributed. If the demand exceeds on-hand inventory, the excess demand is backlogged. Using the echelon stock and demand quantile concepts and an efficient simulation technique, we derive near optimal inventory policy. Additionally we discuss the derived results through the extensive experiments for different supply chain settings.

• Journal of applied mathematics & informatics
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• v.42 no.2
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• pp.379-390
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• 2024

This study proposes a fuzzy inventory model for managing large-scale production, incorporating cost considerations. The model accounts for two types of expenditure scenarios-parametric and exponential. Uncertainty surrounds holding costs, setup costs, and demand rates. The approach considers a supply chain system with a complex manufacturing process, factoring in transportation costs based on the quantity of goods and distance between the supplier and retailer. The initial crisp model is then transformed into a fuzzy simulation, incorporating specific fuzzy variables affecting inventory costs. The proposed method significantly reduces overall inventory costs for the entire supply chain. Retailer demand is linked to inventory levels, and vendor/distributor storage deteriorates over time. The fuzzy condition assumes hexagonal variables for all associated factors. The study employs the signed distance method for defuzzification to determine the optimal order quantity with hexagonal fuzzy numbers. Mathematical examples are provided to illustrate the practicality of the proposed approach.

• Child Health Nursing Research
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• v.18 no.4
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• pp.207-213
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• 2012

Purpose: This study was done to examine levels of temperament, parent-child attachment and depression of adolescents and verify its effects. Methods: Surveys were conducted with 500 students from two middle schools, one located in Seoul and one in Gyeonggi Province. Adolescent temperament was measured using the Junior Temperament and Character Inventory, parent-child attachment using the Revised Inventory of Parent and Peer Attachment and depression using the Children's Depression Inventory. Cluster, t-test, correlation and logistic regression were used for data analysis. Results: Characteristics of temperament were classified into 2 groups. The 'Adaptation vulnerable group' showed high Harm Avoidance and the 'Adaptation protective group' showed high Reward Dependence, and Patience. The 'Adaptation vulnerable group' showed lower attachment and higher depression than the 'Adaptation protective group'. Novelty Seeking and Harm Avoidance correlated positively with depression and negatively with attachment. Students with higher levels of attachment reported lower levels of depression. The logistic regression analysis showed that the 'Adaptation vulnerable group' was 2.16 times more likely to be affected by depression than 'Adaptation protective group'. Conclusion: Results of this study can be used to develop depression intervention programs for adolescent psychological health and provide encouragement in the development of parent-child attachment.

• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.385-397
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• 1995

The purpose of this study is to document the stress symptoms (Anxiety and depression) among dental students and the difference of stress level between classes and by gender. All students in dental college, Seoul National University, in the 1995 academic year, were tested with the Spielberger's State-Trait Anxiety Inventory and Beck Depression Inventory just before the first semestral examination when the stress levels of students are expected to be the highest. 303 students answered the test. The obtained results were as follows : 1. State Anxiety inventory scores of the second-year and first-year students were significantly higher than those of the fourth -year and third-year(p(0.01), and all classes showed mean state anxiety scores more than mild. 2. Trait Anxiety inventory scores of the second-year and first-year students were significantly higher than those of the third-year and forth-year(p(0.01), and all classes showed mean Trait Anxiety scores more than mild. 3. Beck Depression inventory scores of the second -year students were significantly higher than those of the third-year and fourth-year(p(0.01), and twenty two students(7.3%) among the fourth classes showed depression symptoms. 4. In the comparison of the mean scores of the State-Trait Anxiety Inventory and Beck Depression Inventory between male and female students, State Anxiety Inventory scores of the second-year female students were significantly higher than those of the second year male students(p(0.05), and there was no significant difference elsewhere.

• Journal of Preventive Medicine and Public Health
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• v.21 no.1 s.23
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• pp.195-206
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• 1988

Two major issues of the blood bank management are quality assurance and inventory control. Recently, in Korea blood donation has gained popularity increasingly to allow considerable improvement of the quality assurance with respect to blood collection, transportation, storage, component preparation skills and hematological tests. Nevertheless the inventory control, the other issue of blood bank management, has been neglected so far. For the supply of blood by donation barely meets the demand, the blood bank policy on the inventory control has been 'the more the better.' The shortage itself by no means unnecessitate inventory control. In fact, in spite of shortage, no small amount of blood is outdated. The efficient blood inventory control makes it possible to economize the blood usage in the practice of state-of-the-art medical care. For the efficient blood inventory control in Korean hospitals, this tudy is to develop formulae forecasting the standard blood inventory level and suggest a set of policies improving the blood inventory control. For this study informations of $A^+$ whole bloods and packed cells inventory control were collected from a University Hospital and the Central Blood Bank of the Korean Red Cross. Using this informations, 1,461 daily blood inventory records were formulated.48 varieties of blood inventory control environment were identified on the basis of selected combinations of 4 inventory control variables-crossmatch, transfusion, inhospital donation and age of bloods from external supply. In order to decide the optimal blood inventory level for each environment, simulation models were designed to calculate the measures of performance of each environment. After the decision of 48 optimal blood inventory levels, stepwise multiple regression analysis was started where the independent variables were 4 inventory control variables and the dependent variable was optimal inventory level of each environment. Finally the standard blood inventory level decision rule was developed using the backward elimination procedure to select the best regression equation. And the effective alternatives of the issuing policy and crossmatch release period were suggested according to the measures of performance under the condition of the standard blood inventory level. The results of this study' were as follows ; 1. The formulae to calculate the standard blood inventory level($S^*$)was $S^*=2.8617X(d)^{0.9342}$ where d is the mean daily crossmatch(demand) for a blood type. 2. The measures of performace - outdate rate, average period of storage, mean age of transfused bloods, and mean daily available inventory level - were improved after maintenance of the standard inventory level in comparison with the present system. 3. Issuing policy of First In-First Out(FIFO) decreased the outdate rate, while Last In-First Out(LIFO) decreased the mean age of transfused bloods. The decrease of the crossmatch release period reduced the outdate rate and the mean age of transfused bloods.

• Industrial Engineering and Management Systems
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• v.16 no.1
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• pp.52-63
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• 2017

The inventory level of concurrent spare parts (CSP) has a significant impact on the availability of a weapon system. A failure rate function might be of particular importance in deciding the CSP inventory level. We developed a CSP optimization model which provides a compromise between purchase costs and shortage costs on the basis of the Weibull and the exponential failure rate functions, assuming that a failure occurs according to the (non-) homogeneous Poisson process. Computational experiments using the data obtained from the Korean Navy identified that, throughout the initial provisioning period, the optimization model using the exponential failure rate tended to overestimate the optimal CSP level, leading to higher purchase costs than the one using the Weibull failure rate. A Pareto optimality was conducted to find an optimal combination of these two failure rate functions as input parameters to the model, and this provides a practical solution for logistics managers.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.2
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• pp.145-151
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• 2015

As order quantity is increased, the ordering cost per item will be cheaper due to saving of transportation and material handling costs. In this paper, two realistic assumptions such as quantity discount and budget limit are considered. Quantity discount means that all units in the order will be discounted according to the predetermined order levels. Budget limit represents that the costs for inventory investments are bounded. This paper develops a Lagrangian relaxation approach for a continuous review inventory model with a budget constraint and quantity discounts. Computational results indicate that the proposed approach provides a good solution. Sensitivity analysis is done to get some insights on budget limit and quantity discount. As budget limit or the amount of discount according to order quantity is increased, order quantity is increased, whereas reorder point is not always increased.

• IE interfaces
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• v.16 no.1
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• pp.111-116
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• 2003

Business integration has been considered as one of the most critical success factors that enable the firms to gain competitive edges. Despite this trend, it has also been found among not a few companies that the activities that should be functionally tied with are performed even independently. In this study, an integrated model of production planning and inventory has been developed. Computerization of the production planning activities is proposed and implemented. We also proposed the reasonable inventory levels of each item using historic data of the items, which are composed of safety stock from the given fill-rate, operating stock from the production patterns, and reserved stock from the production planning. This study has helped the firm to have clearer job definition of the related processes, to tightly control the inventory by setting and tracing the reasonable fill rates for every product, and to quickly respond to the market changes through the computerized production planning process.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.159-160
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• 2021

From the simulation results, under the collaborative platform of big data based on coordination of the beer industry to mobilize the supply chain operation condition, supply chain direct logistics inventory are in a relatively stable value, and there is no zero inventory or even a serious lack of beer in the stock situations like traditional beer supply chain operation, which avoid the situation of demand information expansion caused by chain inventory levels report because of the serious lack of supply.

• Research in Community and Public Health Nursing
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• v.24 no.2
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• pp.135-142
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• 2013

Purpose: The purpose of this study is to explore influencing factors which contribute to the suicidal ideation in community residents who have ever experienced suicidal attempts. Methods: The subjects of this study were a total of 165 local residents with some experiences of suicidal attempts in B City and K Province. The data were collected from May 1st to October 30th, 2012 and self-report questionnaires including Suicidal Ideation Inventory, Self-Esteem Inventory, Depression, Family and Social Support Inventory were used as a measurement tool. The data were analyzed using t-test, ANOVA, Pearson correlation coefficients, multiple regression with the SPSS/WIN 18.0 program. Results: The average score of suicidal ideation in the local residents with experiences of suicidal attempts was $12.7{\pm}6.25$. Predicted factors on suicidal ideation in the local residents with experiences of suicide attempts included self-esteem, depression and physical illness, and the suicidal ideation has a variance explanation power of 54%. Conclusion: The development and application of intervention programs, which can help to increase self-esteem levels and decrease depression levels among community residents with experiences of suicidal attempts, are first needed. Furthermore, nursing services of customized self-management for people with physical disabilities are needed on the basis of their own physical problems.