• Journal of Korean Institute of Industrial Engineers
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• v.14 no.2
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• pp.81-90
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• 1988

This paper is concerned with warranty cost models for a product with two types of failure ; type 1 failures corrected by minimal repair and type 2 failures removed only by replacement. Two warranty policies involving an initial free service period followed by a pro-rata period are considered ; the difference is whether the warranty is renewed or not when type 2 failure occures during its free service period. Expected warranty costs under the two policies are obtained, and their behaviors are examined for the case where type 1 and 2 failure distributions are Weibull and exponential, respectively.

• Clinics in Shoulder and Elbow
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• v.17 no.3
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• pp.120-126
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• 2014

Background: To compare the treatment of the proximal humerus fracture using a Polarus nail or Philos plate, we aimed to analyze the functional recovery and the factors affecting the selection between the two types of surgery. Methods: The study included 107 patients with proximal humerus fracture who underwent surgery at our institution. Of these patients, 67 underwent surgery with Polarus nails (G1) and 40 with Philos plates (G2). In G1, the cases of two- and three-part fractures were 60 and 7 cases, in G2, the cases of two-, three-, and four-part fractures were 28, 10, and 2 cases, respectively. The average age was 61 years old, and the average follow-up period was 32.5 months. We compared radiological results, the functional recovery retrospectively. Results: The radiological union time was 6.8 weeks and 8.7 weeks on average in G1 and G2 (p < 0.05). At the one-year follow-up period, these were visual analogue scale (VAS) 1.355, forward flexion (FF) 130.968, external rotation (ER) 50.161, internal rotation (IR) L2 in G1, and VAS 0.781, FF 135.806 ER 51.25, IR L1 in G2, respectively, showing no significant differences between the two groups (p > 0.05). Similar observations were made at the final follow-up. In terms of functional recovery, no significant differences were seen at the one-year or at the final follow-up period (p > 0.05). Conclusions: For the surgical treatment of proximal humeral fracture, the selection of the type of surgery is affected by the fracture pattern. However, both methods give satisfactory outcomes and do not show significant differences in the functional outcome after the surgery.

• Journal of Digital Convergence
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• v.16 no.7
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• pp.19-26
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• 2018

This study is purposed to analyze how the utilization of rehabilitation services and the desire for service utilization changes with time, to explain the factors affecting service needs and to suggest direction of policy improvement for injured workers. Using the Workers' Compensation Insurance Panel Data ver.1~3, this study analyzed 5,004 observations. Panel regression analysis was performed using STATA to examine changes over time. Two key findings were made: first, the factors influencing the degree of need for rehabilitation services were age, educational period, ability on job performance, community service experience, re-employment and unemployment; second, the significant factors influencing the degree of need for rehabilitation services according to time were age, education period, unemployment, ability on job performance, and experience in using community services. That results were different from the previous cross-section analysis. These findings indicate that it is necessary to check and adjust the initial intervention contents after the end of the period of care on a timely base.

• The Korean Journal of Health Service Management
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• v.5 no.2
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• pp.35-51
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• 2011

The purpose of this study is to examine relations between the job stress of radiologists, who are serving at secondary medical institutions, and their intent of separation, providing basic information necessary to earlier prevent the separation, improve the quality of radiologists and ensure a more effective personnel management of the professionals. For the purpose, this researcher conducted a structured questionnaire survey of 221 radiologists from Nov 1 to 30, 2010 who were serving at secondary medical institutions located in Busan. Findings of the study can be summarized as follows. 1) The surveyed radiologists were scored 2.82 points in average in terms of job stress. This indicates that they are suffering from job stress higher than moderate. 2) The subjects were significantly different from each other in job stress according to their age, total service period, department where they were serving, satisfaction with their hospital and satisfaction with the foresaid department. 3) The subjects were scored 2.59 points in average in terms of the intent of separation. This indicates that the surveyed radiologists are not so willing to change their job. 4) Those radiologists were significantly different from each other in the intent of separation according to their age, marital status, educational background, average monthly income, total service period, the period of service at a department where they belonged now, position, satisfaction with their hospital and satisfaction with the foresaid department. 5) There were significant correlations between the subjects' job stress and intent of separation.

• IE interfaces
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• v.17 no.spc
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• pp.62-68
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• 2004

HAPS (High Altitude Platform Station) which is defined as a station located on an object at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the earth is a promising technology capable of providing broadband multimedia services. In this study, economical aspects of HAPS service are analyzed by estimating the revenue and costs incurred by the service. To evaluate the profitability of HAPS service, the number of subscribers is estimated and then the net present value (NPV), payback period, and the rate of return on investment (ROI) are calculated under various scenarios.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.37
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• pp.31-40
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• 1996

The amount of safety stock is decided from various information such as the forecasted demand, the lead time, the size of the order quantity and the desired service level. There are two cases to consider the problem of setting safety stock when both the demand in a period and the lead time are characterized as random variables: the first case is the parameters of the demand and lead time distributions are known, the second case is they are unknown and must be estimated. The objective of this study is to present the procedure for setting safety stocks in the case the parameters of the demand and lead time distributions are unknown and must be estimated. In this study, a simple exponential smoothing model is used. to generate the estimates of demand in each period and a discrete distribution of the lead time is developed from historical data, and the optimal service level is used which determined to consider both of a backorder and lost sale.

• The Korean Journal of Health Service Management
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• v.8 no.2
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• pp.1-10
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• 2014

This study examined nonpatient revenues of university hospitals in korea. The data source for this study was 22 university hospitals over the period 2010-2012. In this study, patient revenues, patient expenses, operating profit, nonpatient revenues, total revenues, operating margin, normal profit to gross revenues, ratio of the nonpatient revenues in the total revenues were analysed by the annual and three-year average. The analysis of nonpatient revenue differences by hospital type, bed size, location, management performance was performed by T-test and oneway ANOVA. The results were as follows. First, nonpatient revenues of university hospitals were increased during the period 2010-2012. Second, nonpatient revenues according to hospital type, bed size, location in the university hospitals had significant difference. Third, hospital type was significantly associated with normal profit to gross revenues which was profitability index about nonpatient revenues. Based on these results, this study suggests implications to diversify for management performance in hospitals.

• Journal of the Korea Safety Management & Science
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• v.11 no.1
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• pp.205-211
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• 2009

In reality, distribution planning for a supply chain is established using a certain probabilistic distribution estimated by forecasting. However, in general, the demands used for an actual distribution planning are of deterministic value, a single value for each of periods. Because of this reason the final result of a planning has to be a single value for each period. Unfortunately, it is very difficult to estimate a single value due to the inherent uncertainty in the probabilistic distribution of customer demand. The issue addressed in this paper is the selection of single demand value among of the distributed demand estimations for a period to be used in the distribution planning. This paper proposes an efficient demand selection scheme for minimizing total inventory costs while satisfying target service level under the various experimental conditions.

• Korean Journal of Veterinary Research
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• v.49 no.3
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• pp.201-205
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• 2009

In this study, we evaluated the stability and potency of live attenuated rinderpest vaccines of lapinized-avianized tissue culture strain origin, which had been produced annually from 2005 to 2008. When immune responses to the vaccines were evaluated using two Holstein calves weighing 100~150 kg, neutralizing antibody titer of 1 : 16 was induced at 21 days post vaccination. When calves were also inoculated with vaccines lots that had been stored for 39 months at ${4^{\circ}C}$, same level of antibody titer was observed. Using the virus titer test, we found that all batches of the vaccine that had been kept for 3, 10, 15, 22, 27, 34, 39, and 45 months showed no significant loss of titers, and fulfilled the requirement necessary ($\geq$ 3 $logTCID_50$) to be used as the national rinderpest vaccine reserve in Korea. In this study, we demonstrated that stability and potency of the rinderpest vaccines were maintained over three years when kept at ${4^{\circ}C}$ storage. This indicates that it maybe feasible to extend the expiration period of this vaccine from one year to three years.

• Journal of Digital Convergence
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• v.8 no.2
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• pp.13-28
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• 2010

Korean service industry has been rapidly growing so far and economic trends in korea is shifting to service economy. However Information Communication Technology (ICT) investment and use in service sector are still relatively low in comparison with US. Keeping the current state of the service industry in mind, this paper is to review the potential productivity growth of service industry empirically by analyzing the effect of ICT on total factor productivity after investing the ICT using outlook of Korean service industry. The results show that service sectors, with more using ICT, show high productivity growth and stable TFP change during the financial period. Sectors with lower using ICT are more sensitive to changes in the business environment when compare to sectors with highly using ICT. Concerning the period of 1997-1999, the TFP growth of most of sectors slowed down and turned to recovery immediately afterwards, 2000-2002.