• Proceedings of the Korean Operations and Management Science Society Conference
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• 1999.04a
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• pp.426-426
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• 1999

;There are many sources of uncertainty in a typical production and inventory system. There is uncertainty as to how many items customers will demand during the next day, week, month, or year. There is uncertainty about delivery times of the product. Uncertainty exacts a toll from management in a variety of ways. A spurt in a demand or a delay in production may lead to stockouts, with the potential for lost revenue and customer dissatisfaction. Firms typically hold inventory to provide protection against uncertainty. A cushion of inventory on hand allows management to face unexpected demands or delays in delivery with a reduced chance of incurring a stockout. The proposed strategies are used for the design of a probabilistic inventory system. In the traditional approach to the design of an inventory system, the goal is to find the best setting of various inventory control policy parameters such as the re-order level, review period, order quantity, etc. which would minimize the total inventory cost. The goals of the analysis need to be defined, so that robustness becomes an important design criterion. Moreover, one has to conceptualize and identify appropriate noise variables. There are two main goals for the inventory policy design. One is to minimize the average inventory cost and the stockouts. The other is to the variability for the average inventory cost and the stockouts The total average inventory cost is the sum of three components: the ordering cost, the holding cost, and the shortage costs. The shortage costs include the cost of the lost sales, cost of loss of goodwill, cost of customer dissatisfaction, etc. The noise factors for this design problem are identified to be: the mean demand rate and the mean lead time. Both the demand and the lead time are assumed to be normal random variables. Thus robustness for this inventory system is interpreted as insensitivity of the average inventory cost and the stockout to uncontrollable fluctuations in the mean demand rate and mean lead time. To make this inventory system for robustness, the concept of utility theory will be used. Utility theory is an analytical method for making a decision concerning an action to take, given a set of multiple criteria upon which the decision is to be based. Utility theory is appropriate for design having different scale such as demand rate and lead time since utility theory represents different scale across decision making attributes with zero to one ranks, higher preference modeled with a higher rank. Using utility theory, three design strategies, such as distance strategy, response strategy, and priority-based strategy. for the robust inventory system will be developed.loped.

• Clinics in Orthopedic Surgery
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• v.10 no.4
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• pp.398-406
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• 2018

Background: Hypoalbuminemia (serum albumin < 3.5 g/dL) is associated with increased morbidity and mortality in patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, costs associated with hypoalbuminemia remain unknown. This study investigated the effect of serum albumin on direct treatment costs, length of stay (LOS), and readmissions for primary and revision THA and TKA patients. Methods: All adult patients at a single institution undergoing primary or revision THA or TKA between January 2014 and December 2016 were retrospectively reviewed. Patients were stratified by preoperative serum albumin level. The primary outcome was total direct costs at index hospitalization. Secondary outcomes included LOS and readmission within 30 days. Multivariable regressions were utilized to adjust for demographics and comorbidities. Results: Of 3,785 patients, 114 (3.0%) had hypoalbuminemia. After adjustment, hypoalbuminemia was associated with a 16.2% increase in costs (${\beta}=0.162$; 95% confidence interval [CI], 0.112 to 0.213; p < 0.001), representing an average cost increase of $3,383 (95% CI, $2,281 to $4,485) relative to costs for serum albumin > 4.5 g/dL. The increased total costs were significantly higher in revision ($4,322, p = 0.034) than in primary ($3,446, p < 0.001) procedures. In adjusted regression, each 1.0 g/dL increase in serum albumin yielded a 6.6% reduction in costs (${\beta}=-0.066$; 95% CI, -0.090 to -0.042]; p < 0.001), for average savings of $1,282 (95% CI, $759 to $1,806) per unit albumin. Adjusted regressions demonstrated that a 1-point increase in serum albumin reduced readmissions by 53% (odds ratio, 0.47; 95% CI, 0.31-0.73; p = 0.001) and LOS by 0.6 days (${\beta}=-0.60$; 95% CI, -0.76 to -0.44; p < 0.001). Conclusions: Hypoalbuminemia is associated with increased total direct costs, LOS, and readmissions following primary and revision THA and TKA. Future efforts to predict and address total costs should take into consideration the patient's preoperative serum albumin levels.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.1
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• pp.55-67
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• 2010

Decision problem called an optimal release policies, after testing a software system in development phase and transfer it to the user, is studied. The applied model of release time exploited infinite non-homogeneous Poisson process. This infinite non-homogeneous Poisson process is a model which reflects the possibility of introducing new faults when correcting or modifying the software. The failure life-cycle distribution used generalized gamma type distribution which has the efficient various property because of various shape and scale parameter. Thus, software release policies which minimize a total average software cost of development and maintenance under the constraint of satisfying a software reliability requirement becomes an optimal release policies. In a numerical example, after trend test applied and estimated the parameters using maximum likelihood estimation of inter-failure time data, estimated software optimal release time.

• Convergence Security Journal
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• v.8 no.4
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• pp.121-126
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• 2008

It is of great practical interest to decide when to stop testing a software system in development phase and transfer it to the user. This decision problem called an optimal release policies. In this paper discussed to specify an optimal release policies. In this paper, propose an optimal release policies of the life distribution applied Erlang distribution of special pattern of Gamma distribution. In this paper, discuss optimal software release policies which minimize a total average software cost of development and maintenance under the constraint of satisfying a software reliability requirement. From Sensitivity Analysis, make out estimating software optimal release time.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.5
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• pp.29-38
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• 2018

This study aims to propose a method for the estimation of operational delay cost using transportation card data in bus accidents. Average operational delay time from bus accidents was surveyed among 12 bus companies through an interview method. Then, the operational delay cost was estimated using actual traffic accident data and transportation card data. Results showed that average loss time per bus accident was found to be 45 minutes. In addition, total occupancy of 659 was estimated for the accidents investigated using transportation card data, resulting a total loss time of 494.25 hours. An estimated operational delay cost was 186.9 thousand won per accident, which was 6.37% of social agency cost. The magnitude of this number implied that operational delay cost may have a significant impact on traffic accident cost if included.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.34 no.2
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• pp.53-69
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• 2021

Objectives : The purpose of this study is to analyze the effects of treatment between Western medicine and Korean medicine on Allergic rhinitis patients using national population-based claim data from the Health Insurance Review and Assessment Service. Methods : The subjects of the study were 30,024 patients in the Korean medicine group and 30,024 in the Western medicine group who were diagnosed with Allergic rhinitis from September 1, 2018 to December 31, 2018. Propensity score analysis was used for matching age, sex, etc. at a ratio of 1:1. Cox regression and subgroup analysis were used to estimate the adjusted hazard ratio of recurrence, Asthma, and Atopic dermatitis in Korean medicine group and Western medicine group. In addition, the total treatment period, total treatment cost, and average cost per day of visit were compared and analyzed. Results : Compared to Korean medicine, Western medicine had a significantly higher risk of recurrence at 1.701 times, Asthma occurrence risk at 1.609 times and Atopic dermatitis occurrence risk at 1.098 times. Compared to Western medicine, the total treatment period of Korean medicine was 14.27 days longer, the total treatment cost was 53,591 won more, and the average cost per day was 7,539 won more. Conclusions : This study is a retrospective cohort study using the propensity score matching in Korea to compare the outcomes of Allergic rhinitis between Western medicine and Korean medicine. Further research is needed by considering patients characteristics, and linking with additional data.

• Journal of Nutrition and Health
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• v.36 no.5
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• pp.528-535
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• 2003

The purposes of this study were: 1) to investigate the operational and financial characteristics of contract-managed high school food services in Seoul, 2) to analyze the financial performance of high school food services 3) to develop guidelines for meal pricing and facilities investment costs. From Oct to Nov 2001, questionnaires were mailed to 249 high schools that were managed by contract food service companies. A 40.2％ response rate was recorded. The results of this study were as follows: 1. Student enrollment in high schools run by contract-managed food services was 1,518, with a 68.5％ participation rate in the school lunch program. The average meal price was 2,141 won. 2. Based on the income statement analysis, average total sales were 410,440,504 won and average net profit was 16,098,558 won. 3. The optimum food cost per meal was 1,200-1,300 won per meal, calculating using the methods of conversion factor, RDA (Recommended Daily Allowance), and nutrient exchange unit. 4. Guidelines for meal pricing were developed using the modified actual pricing method based on facilities investment cost, number of meals and food cost. The ratio of labor cost, general management expenses and ordinary profit were adopted from the schools with liability. The food cost, depreciation and interest cost were calculated based on unit meal. 5. The guideline for facilities investment was developed based on the number of meals, meal price and food cost. The guideline included the maximum facilities investment cost paid by the contract food service management company. (Korean J Nutrition 36(5): 528∼535, 2003)

• Korean Journal of Clinical Pharmacy
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• v.31 no.2
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• pp.153-159
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• 2021

Background: With increasing economic evaluation studies on the treatment of or screening tools for liver diseases that cause hepatocellular carcinoma (HCC), interest in the analysis of the medical utilization and costs of HCC treatment is increasing. Therefore, we aimed to estimate the medical utilization and costs of HCC patients, and calculate the cost of main procedures for HCC treatment, including liver transplant (LT), hepatic resection (HR), radiofrequency ablation (RFA), and transarterial chemoembolization (TACE). Methods: We analyzed claim data from January to December 2018 from the Health Insurance and Review and Assessment Service-National Patient Sample (HIRA-NPS-2018) dataset, including data of patients diagnosed with HCC (Korean Standard Classification of Diseases code C22.0) who had at least one inpatient claim for HCC. Results: A total of 715 HCC patients were identified. In 2018, the yearly average medical cost per HCC patient was ₩18,460K (thousand), of which ₩14,870K was attributed to HCC. Among the total medical costs of HCC patients, the inpatient cost accounted for the largest portion of both the total medical and HCC-related costs. The major procedures of HCC treatment occurred most frequently in the order of TACE, RFA, HR, and LT. The average medical cost per treatment episode was the highest for LT (₩87,280K), followed by HR (₩10,026K), TACE (₩4,047K), and RFA (₩2,927K). Conclusion: By identifying the medical costs of HCC patients and the costs of the main procedures of HCC treatment, our results provide basic information that could be utilized for cost estimation in liver disease-related economic evaluation studies.

• Journal of Korean Society for Quality Management
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• v.17 no.1
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• pp.11-18
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• 1989

A one-upper level warehouse n-Iower level retailer inventory distribution model is discussed. This paper presents the parallel-type inventory structure using an order-up-to-level invertory control system for analyzing the approximation of the expected units back ordered and the measure of service. We find that the total expected backorder units in system can substitute the expected back orders in the last two periods for the expected back orders in total periods. The rate of total expected back orders which is the measure of disservice, is given by dividing the improved units of total expected backorder into the total demand during an order cycle. The average annual total cost in system is obtained by considering the results, but from the viewpoint of this study the cost analysis is not described.

• Journal of the Korean Solar Energy Society
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• v.26 no.1
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• pp.21-28
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• 2006

Changes in building construction methods and repairing of older buildings have reduced infiltration rate. Synthetic materials, release airborne particles and uneven healthy odor are increased. For preventing pollutants introduce fresh outdoor air into the building, simply letting fresh outdoor air into building, however, Is not a cost-effective way to ventilation. When additional ventilation is added to an existing HVAC system, the heating and cooling equipment, often cannot handle the increased load. A HRV provides a way to minimize in energy costs while introducing fresh air to a building. In this study, the economical research of HRV, made of three types of materials, are conducted. Heat recovering characteristics are studied at seasonal outdoor air conditions based on the outdoor air property condition at, Seoul in 2002. As a results, the average sensible effectiveness is 0.75 in the sensible heat exchanger and average total effectiveness is 0.65 in the total heat exchanger. The pay back period of the sensible heat exchangers are $3.2{\sim}3.5$ year and it of total heat exchanger is 2.2 years.