• Journal of Korean Society for Quality Management
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• v.21 no.2
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• pp.109-120
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• 1993

Most systems are composed of components which have different failure chracteristics. Since the failure characteristics of components is different, it is rational and reasonable to establish a maintenance model to be considered repair and replacement policies which are proper to failure characteristics of these components. This paper proposes the age replacement time for a system composed of components which have different failure characteristics. In this model, it is assumed that a system is composed of a critical failure component, a major failure component, minor failure component. If any failure occurs to critical component before its age replacement time, the system should be replaced. If any failure does not occur until its age replacement time, preventive replacement should be performed at age replacement time T. Major component is minimal repaired if any failure occurs during operation. Minor component should be replaced as soon as failure is found. This paper determines the optimal replacement time of the system which minimize, total maintenance cost and initial stock Quantity of minor component within this optimal replacement time. Numerical example illustrates these results.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.4
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• pp.487-493
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• 2007

In this paper, we deal with an optimal software-release problem of determining the time to stop testing and release the software system to the user. The optimal release time problem is considered from maintenance like the periodic distribution of service packs and the unpredictable distribution of patches after the release. Moreover, the environment of software error-detection during operation differs from the environment during testing. This paper proposes the software reliability growth model which incorporates periodic service packs, unpredictable patches and operational environment. Based on the proposed model, we derive optimal release time to minimize total cost composed of fixing an error, testing and maintenance. Using numerical examples, optimal release time is determined and illustrated.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.165-173
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• 2000

Analytic models have been developed to solve integrated production-distribution problems in supply chain management (SCM). As one of major constraints in analytic models, capacity, which is the total operation time in this paper has mostly been known or disregarded assuming infinite capacity. Also, as major factors, machine processing time to fabricate or assemble a part or product at a certain machine center in production system and vehicle processing time to deliver a product to a customer by a certain vehicle in distribution system have been fixed and regarded as a static factor, But in the real systems significant differences exit between capacity and the required time to achieve the production-distribution plan and between processing time and consumed time to process a part or product. In this paper, capacity and processing times in the analytic model are considered as dynamic factors and adjusted by the results from independently developed simulation model, which includes general production-distribution characteristics. Through experiments, we obtain the more realistic solutions reflecting stochastic natures by performing the iterative analytic-simulation procedure.

• The Journal of Korean Physical Therapy
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• v.15 no.4
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• pp.151-179
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• 2003

The purpose of this study was to examine the influence of total knee replacement to arthritis patients in pain intensity and functional impairment. For this study, over 50-year-old 30 patients who had osteoarthritis and 69 patients who got total knee replacement at the one of the departments of orthopedics in Daegu were interviewed from June, 2002 to March, 2003. The results of this study were as follows : First, pain intensity was decreased to experimental group after operation than control group(P<.01) And the presence of crepitation was also decreased to them(P<.05). On the other hand there's no significant difference was noted in the presence of stiffness, degree of flexion contracture and extension contracture between two groups. Second, over 91 days group after operation and visitor's group of physiotherapy unit were better than others in Level of knee function(P<.01). Third, over 91 days group after operation and visitor's group of physiotherapy unit were higher than others in Barthel Index of knee function(P<.01). Forth, over 91 days group after operation and visitor's group of physiotherapy unit were higher than others in Level of IADL(P<.05). Fifth, over 91 days group after operation and visitor‘s group of physiotherapy unit were higher than others in Katz Index of knee function(P<.01). Sixth, although Old Ages' Activity Index seemed to get better as time goes by, there's no statistical difference. Seventh, over 91 days group after operation and visitor's group of physiotherapy unit were higher than admission group and under 30 days group after operation in Social Activity Index(P<.05). Eighth, the function of the knee was connected with the abilities in the activity of the old and the social skill. The Barthel index was connected with the function of the knee joint and the activities of the old and Katz index. IADL function was connected with the activities of the old and the social activity. The Katz index was connected with the Barthel index. The activity of the old was connected with the Barthel index, the functional score of the knee joint andthe IADL score. The ability of social skill was connected with the activity of the old, IADL score and the function of the knee.

• Journal of Chest Surgery
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• v.15 no.1
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• pp.46-52
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• 1982

Activities of serum glutamic pyruvic transaminase [SGPT], serum glutamic oxaloacetic transaminase [SGOT] and serum lactic dehydrogenase [LDH] were determined during and after surgery In a total of 18 patients with heart diseases Including 8 cases of congenital heart anomaly and 10 cases of acquired valvular diseases who undergone open heart surgery under cardiopulmonary bypass. The results obtained are as follows: 1]The average value of the activity of SGPT before the surgery was $27.94{\pm}12.24$ units. The value was increased following the operation and reached to the maximum value of $43.83{\pm}37.02$ units 2 days after the operation, which was slightly deviated from the normal range. The enzyme activity returned to the normal range of $32.82{\pm}23.61$ units 4 days after the operation. 2]The average value of the activity of SGOT before the surgery was observed to be $30.5{\pm}11.29$ units. The value increased during the operation and reached to the maximum value of $95.56{\pm}43.38$ units. 2 days after the operation, the enzyme activity was gradually decreased thereafter and returned to the normal range 6 days after the operation. 3]The average value of the activity of serum LDH before the surgery was found to be $258.0{\pm}88.96$ units. The value was increased during the operation and reached to the maximum value of $930.55{\pm} 258.23$ units 2 days after the operation. The enzyme activity was gradually decreased thereafter and returned to normal range 7 days after the operation. 4]It was observed that the longer the time required for the extracorporeal circulation in the open heart surgery became, the greater the changed in activity of SGOT, SGPT and serum LDH were found.

• Archives of Plastic Surgery
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• v.40 no.6
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• pp.721-727
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• 2013

Background One of the main concerns in orbital blowout fracture repair is a narrow operation field, due mainly to the innate complex three dimensions of the orbit; however, a deep location and extensive area of the fracture and soft tissue edema can also cause concern. Swelling of the orbital contents progresses as the operation continues. Mannitol has been used empirically in glaucoma, cerebral hemorrhage, and orbital compartment syndrome for decompression. The authors adopted mannitol for the control of intraorbital edema and pressure in orbital blowout fracture repair. Methods This prospective study included 108 consecutive patients who were treated for a pure blowout fracture from January 2007 to October 2012. For group I, mannitol was administered during the operation. Under general anesthesia, all patients underwent surgery by open reduction and insertion of an absorbable mesh implant. The authors compared postoperative complications, the reoperation rate, operation time, and surgical field improvement between the two groups. Results In patients who received intraoperative administration of mannitol, the reoperation rate and operation time were decreased; however, the difference was not statistically significant. The total postoperative complication rates did not differ. Panel assessment for the intraoperative surgical field video recordings showed significantly improved vision in group I. Conclusions For six years, mannitol proved itself an effective, reliable, and safe adjunctive drug in the repair of orbital blowout fractures. With its rapid onset and short duration of action, mannitol could be one of the best methods for obtaining a wider surgical field in blowout fracture defects.

• Korean Medical Education Review
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• v.20 no.2
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• pp.112-117
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• 2018

Attending the operation room is an essential part of surgical clerkships. Syncope or presyncopal attacks in the operation room may negatively affect students' learning and career development. This study set out to identify the prevalence of syncope and presyncopal attacks in the operation room during medical students' surgical clerkships. Data from 420 medical students (303 men and 117 women) in their 3rd year of clerkship were collected between 2014 and 2017. An anonymous questionnaire was distributed to assess the prevalence and degree of syncope and presyncopal symptoms. A total of 27% of the respondents had experienced syncope or presyncopal symptoms, 49.6% of the female students and 18.8% of the male students (p<0.001). Fifty students (43.5%) had been attending as observers at the time of the syncopal attack, while 65 students (56.5%) had been participating as assistants. Thirty-four students (29.6%) had recently eaten at the time of the syncopal attack, while 81 students (70.4%) had not recently eaten. Prodromal symptoms included the urge to sit down (21.2%), sweating (19.3%), nausea (16.9%), a feeling of warmth (13.3%), darkened vision (12.6%), yawning (11.7%), palpitation (11.0%), ear fullness (10.2%), black spots in one's vision (7.6%), and hyperventilation (7.1%). This study showed the prevalence of syncope and presyncopal symptoms in the operation room during surgical clerkships. For students' safety and effective clerkship learning, thorough proactive education on syncopal attacks is required.

• International Commerce and Information Review
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• v.7 no.2
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• pp.75-94
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• 2005

This study is focused on evaluating the computer-integrated just-in-time (CI-JIT) production system of a semi-conductor manufacturing firm in Korea. Approaching the mid-1980s, the emphasis was on low price, low-cost operations, and quality, especially in USA. American companies have shifted output to low-wage countries like the Philippines, Korea, Japan, Malaysia and allied countries that can make quality products at low prices. Korea and other Asian countries forego short-term profits to gain a solid foothold in a product market, recognizing that larger market share leads to lower cost and higher profit in the long run. They bring manufacturers and suppliers together to improve material management and operation management, using project teams that investigate topics, such as Just-In-Time(JIT)manufacturing, among others. The "Kanban" word means "card" in Japanese, and is used to indicate the desired final delivery schedule. The operation for a particular item produced is scheduled for a specific time. The same process is extended to the external suppliers. More recently, the cards are gradually being replaced by electronic procedures that follow the same concept. Its capacity must be capable of handling the various transactions required by the JIT coverage as well as some allowances for expanded applications.

• Hip & pelvis
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• v.35 no.1
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• pp.47-53
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• 2023

Purpose: The purpose of this study is to compare the radiological results of fixation using the femoral neck system (FNS) and cannulated screw (CS) for treatment of femoral neck fractures. Materials and Methods: A retrospective study of patients with femoral neck fractures who underwent internal fixation and had follow-up of more than six months from 2010 to 2020 was conducted. A total of 87 patients were enrolled in the study. The FNS group included 20 patients and the CS group included 67 patients. Classification of fractures was performed according to Garden and Pauwels classification. Operation time, intraoperative blood loss, sliding distance of the implant, lateral soft tissue irritation caused by implants, and complications were evaluated. Results: The mean operation time was 40.30 minutes in the FNS group and 46.84 minutes in the CS group. The mean intraoperative bleeding volume was 51.25 mL in the FNS group and 72.16 mL in the CS group. Bone union was achieved in 18 patients in the FNS group (90.0%) and in 61 patients in the CS group (91.0%). The mean sliding distance of the implant was 4.06 mm in the FNS group and 3.92 mm in the CS group. No patients in the FNS group and 12 patients in the CS group complained of soft tissue irritation. Conclusion: A shorter operative time, less intraoperative bleeding, and less irritation of soft tissue were observed in the FNS group. FNS could be an alternative to CS for fixation of femoral neck fractures.

• Journal of Korean Port Research
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• v.10 no.2
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• pp.7-15
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• 1996

A berth assignment problem has a direct impact on assessment of charges made to ships and goods. A berth can be assigned to incoming vessels and operated in tow different ways: as a common user berth, as a preference berth. A common user berth is a berth that any ship calling at a port may be permitted to use according to her time of arrival and to priorities as determined by the port authority. In this paper, we concerned with various types of mathematical programming models for a berth assignment problem to achive an efficient berth operation. In this paper, we focus on a reasonable berth assignment programming in a public container terminal in consideration of trade-off between server and user. We propose a branch and bound algorithm & heuristic algorithm for solving the problem. We suggest three models of berth assignment to minimizing the objective functions such as total port time, total berthing time and maximum berthing time by using a revised Maximum Position Shift(MPS) with which the trade-off between servers and users can be considered. The berth assignment problem is formulated by min-max and 0-1 integer programming and developed heuristic algorithm to solve the problem more easily instead of branch and bound method. Finally, we gave the numerrical solutions of the illustrative examples.