• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.107-112
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• 2015

To predict the system availability of the National Environmental Satellite Center Earth Station, mathematical models of H/W and S/W availability, the availability estimating methods for parallel were systematically presented in this paper. Furthermore, the results of the availability prediction for the Environmental Satellite Earth Station were estimated. The analytical results of Environmental Satellite Earth Station system availability were estimated as 0.998072.

• Journal of Applied Reliability
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• v.4 no.1
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• pp.15-26
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• 2004

Life test is performed to set a confidence (lower) limit on the mean or median life of items if the number of failures at the end of the fixed time t does not exceed a given number c. Gupta(1962) propose a sampling plan for truncated life tests when the life distribution of an item is normal or lognormal distribution. In this paper, based on the result of Gupta(1962), we propose a sampling plan for failure rate test when an item has normal or lognormal life distribution. We assume that the shape parameter is known while the location parameter is unknown.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.2
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• pp.1-10
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• 2012

In this study, software products developed in the course of testing, software managers in the process of testing software test and test tools for effective learning effects perspective has been studied using the NHPP software. The finite failure nonhomogeneous Poisson process models presented and the life distribution applied exponential and log shaped type hazard function. Software error detection techniques known in advance, but influencing factors for considering the errors found automatically and learning factors, by prior experience, to find precisely the error factor setting up the testing manager are presented comparing the problem. As a result, the learning factor is greater than autonomous errors-detected factor that is generally efficient model could be confirmed. This paper, a failure data analysis of applying using time between failures and parameter estimation using maximum likelihood estimation method, after the efficiency of the data through trend analysis model selection were efficient using the mean square error and coefficient of determination.

• Journal of Chest Surgery
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• v.25 no.8
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• pp.863-870
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• 1992

The low profile Ionescu-Shiley pericardial xenograft valve had been initially introduced to have improved hemodynamic performance and expected superior durability, However, subsequent clinical reports and laboratory studies have repeatedly indicated early failure of the valve from mechanical reasons in valve design, A total and consecutive 169 patients underwent isolated MVR with the low profile Ionescu-Shiley valve at Seoul National University Hospital from November 1984 to October 1989 [Group ISLM]. Five patients [3.0%] died within 30 days of surgery, and early survivors were followed up for 734.9 patient-years [Mean$\pm$SD, 4.9$\pm$2.0 years], Late mortality rate was 0.136% /patient-year [pt-yr], Linearized incidences of major complications were: 0.953% embolism /pt-yr; 0.680% bleeding /pt-yr; 0.272% endocarditis /pt-yr; and 0, 408% primary tissue failure [PTF] /pt-yr, The actuarial survival was 99.4$\pm$0.6%, and probabilities of from thromboembolism and from PTF were 90.7$\pm$4.6% and 95.9$\pm$2.6% at 8 years, respectively These results were compared with the clinical data from the 291 patients of isolated MVR with the standard Ionescu-Shiley valve at the same hospital during the period between October 1978 and June 1983 [Group ISUM], Group ISUM included 11% of patients younger than 15 years of age, whereas Group ISLM did no patient of this age. The mean age at the time of surgery was significantly younger in Group ISUM than one in Group ISLM [P<0.001]. Differences were not statistically significant in operative mortality, mean follow-up period and linearized incidences of thromboembolism, bleeding and endocarditis, between two groups, However, the linearized rate of PTF was lower [P<0.001] and probabilities of freedom fro PTF higher [P<0.001] in Group ISLM at least up to postoperative 8 years. While the features of PTF of the standard valve was predominantly degeneration with calcification and stenosis, the ones of the low profile valve was cusp tear and incompetence. It remains, however, to be seen whether the low profile valve fails mostly from mechanical reason, and further follow-up will still be necessary to determine the differences in mode of PTF of two valves.

• The Korean Journal of Pain
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• v.37 no.1
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• pp.59-72
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• 2024

Background: This study assessed the postoperative analgesic efficacy and safety of the quadratus lumborum block (QLB) in pediatric patients. Methods: Electronic databases were searched for studies comparing the QLB to conventional analgesic techniques in pediatric patients. The primary outcome was the need for rescue analgesia 12 and 24 hours after surgery. Secondary outcomes covered the Face-Legs-Activity-Cry-Consolability Scale (FLACC) scores at various time points; parental satisfaction; time to the first rescue analgesia; hospitalization time; block execution time; block failure rates, and adverse events. Results: Sixteen randomized controlled trials were analyzed involving 1,061 patients. The QLB significantly reduced the need for rescue analgesia both at 12 and 24 hours after surgery (12 hours, relative risk [RR]: 0.45; 95% confidence interval [CI]: 0.01, 0.88; 24 hours, RR: 0.51; 95% CI: 0.31, 0.70). In case of 24 hours after surgery, type 1 QLB significantly reduced the need for rescue analgesia (RR: 0.56; 95% CI: 0.36, 0.76). The QLB also exhibited lower FLACC scores at 1 hour (standardized mean difference [SMD]: -0.87; 95% CI: -1.56, -0.18) and 6 hours (SMD: -1.27; 95% CI: -2.33, -0.21) following surgery when compared to non-QLB. Among QLBs, type 2 QLB significantly extended the time until the first rescue analgesia (SMD: 1.25; 95% CI: 0.84, 1.67). No significant differences were observed in terms of parental satisfaction, hospitalization time, block execution time, block failure, or adverse events between QLB and non-QLB groups. Conclusions: The QLB provides non-inferior analgesic efficacy and safety to conventional methods in pediatric patients.

• International Journal of Reliability and Applications
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• v.16 no.1
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• pp.35-53
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• 2015

This investigation deals with reliability and sensitivity analysis of a repairable embedded system with standby wherein repairman takes multiple vacations. The hardware system consists of 'M' operating and 'S' standby components. The repairman can leave for multiple vacations of random length during its idle time. Whenever any operating unit fails, it is immediately replaced by a standby unit if available. Moreover, governing equations of an embedded system are constructed using appropriate birth-death rates. The vacation and repair time of repairman are exponentially distributed. The matrix method is used to find the steady-state probabilities of the number of failed components in the embedded system as well as other performance measures. Reliability indexes are presented. Further, numerical experiments are carried out for various system characteristics to examine the effects of different parameter. Using a special class of neuro-fuzzy systems i.e. Adaptive Network-based Fuzzy Interference Systems (ANFIS), we also approximate various performance measures. Finally, the conclusions and future research directions are provided.

• Journal of Chest Surgery
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• v.18 no.1
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• pp.46-53
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• 1985

A single aortic valve replacement using the lonescu-Shiley bovine pericardial xenograft valve was performed in 66 consecutive patients during the period from February, 1979 to June, 1984. They were 49 males and 17 females with ages ranging from 9 to 61 [mean, 31.113.1] years, and 9 of them were children younger than 15 years of age. Twenty-seven patients [40.9%] required the combined operative procedures to either other valvular lesions or congenital defects. There were 9 early deaths within 30 days of surgery [operative mortality rate, 13.6%] and 2 late deaths thereafter [late mortality rate, 3.0%; or 1.75%/patient-year]. The 57 early survivors were followed for a total duration of 114.2 patient-years [mean, 24.016.0 months]. Four patients experienced thromboembolic complication with no death [3.50%/patient-year]; one died from intracranial bleeding related to anticoagulation [0.88%/patient-year]; one recovered from prosthetic valve endocarditis [0.88%/patient-year]; and four developed aortic regurgitant murmur with none or minimal cardiac symptoms and they were classified into cases of tissue valve failure [3.50%/patient-year]. The actuarial survival rate was 82.34.7% at 6 years, and the actuarial probabilities of freedom from thromboembolism and valve failure were 93.33.9% and 89.15.8% at postoperative 6 years respectively Symptomatic improvement was excellent in most late survivors at the follow-up end with the mean of NYHA Classes of 1.040.19 while the one was 2.290.67 at the time of operation. Excluding the higher operative mortality rates, these clinical results are fully comparable with the ones of reports from the major institutions using the porcine aortic or the bovine pericardial tissue valves and warrants the continued use of the xenograft valve in the aortic position. The importance of more detailed preoperative evaluation of the myocardial function and the need of improved myocardial preservation during surgery for the improved early clinical results were discussed.

• The Journal of the Korean dental association
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• v.49 no.4
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• pp.211-218
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• 2011

Purpose: An impacted tooth is defined as a tooth that shows delayed eruption and is expected to erupt incompletely by clinical and radiograph examination despite it reaching its expected time of eruption. The aims of this study were to investigate the clinical and radiological characteristics and treatment duration and method of impacted teeth in Korean patients. Materials and Methods: For this study we used clinical records, study models, panoramic radiographs and intraoral photographs of patients who attended Gachon University Gil Hospital Orthodontic Department between 2005 and 2008. There were 164 patients with a total number of 202 impacted teeth. Results: Male patients shows a little more prevalence than female patients (1.13:1). The under 12 age group had the highest prevalence of tooth impaction, and the over 19 age group showed the least prevalence of tooth impaction. The ratio of tooth impaction between the left to right ratio was 1.73:1 and maxilla and mandible was 1.84:1. The impacted teeth were most commonly positioned buccally (76 cases, 41.5%). Full nap closure technique (108 cases, 81.2%)was most frequently used for attachment of surgical traction hooks. Maxillary canine impaction was most commonly encountered both in male and female patients. The mean treatment period was 12.2 months and the success rate of treatment was 90.3%. The canine tooth shows the longest treatment time and highest failure rate. The ankylosis was the major cause of failure. Conclusion: Impacted teeth most commonly show in left side maxilla in the under 12 age group. And it is most commonly positioned buccally. The mean treatment period was 12.2 months, and the success rate of treatment was 90.3%.

• Journal of Chest Surgery
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• v.14 no.4
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• pp.381-387
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• 1981

Fourteen Infants with congenital cardiac anomalies underwent primary surgical Intervention within the first 12 months of life. There were eight patients with ventricular septal defect, two with total anomalous pulmonary venous return [TAPVR], and the remainders with tetralogy of Fallot, transposition of great arteries [d-TGA], Taussing-Bing malformation, and coronary A-V fistula. The age of the patients ranged from 5 to 12 months, with a mean age of 9.9 months. The mean weight was 6.7 Kg [3.8 to 9.5 KS]. Congestive heart failure persisting despite intensive medical treatment was present In 8 patients [56%], and was the most common indication for operation. Early operation was necessary in 5 of these patients [35%], because of failure to thrive and recurrent pulmonary infection. In one patient with TOF, frequent hypoxic spell prompted the necessity for early operation. In cases of VSD, TAP. VR, TOF, and coronary A-V fistula, Intracardiac repair was done with conventional cardiopulmonary bypass, chemical cold cardioplegia, and topical myocardial cooling. Deep hypothermic circulatory arrest with surface induced cooling, followed by core cooling and core rewarming, was employed .for better exposure in the cases of d-TGA and Taussing-Bing malformation. The results were however, not satisfactory. The overall mortality was 28 per cent. There were no deaths in the eight patients with VSD. The one with coronary A-V fistula survived. The other 5 cases all expired either on the table or immediately after operation. The non-fatal post-operative complications included low cardiac output, respiratory insufficiency, bleeding, and temporary A-V block. The causes of death were prolonged circulatory arrest time in d-TGA, complete A-V block and low cardiac output in TOF and Taussing-Bing malformation and prolonged bypass time and Inadequate correction in TAPVR.

• Journal of Chest Surgery
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• v.14 no.4
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• pp.388-398
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• 1981

Fourteen Infants with congenital cardiac anomalies underwent primary surgical Intervention within the first 12 months of life. There were eight patients with ventricular septal defect, two with total anomalous pulmonary venous return [TAPVR], and the remainders with tetralogy of Fallot, transposition of great arteries [d-TGA], Taussing-Bing malformation, and coronary A-V fistula. The age of the patients ranged from 5 to 12 months, with a mean age of 9.9 months. The mean weight was 6.7 Kg [3.8 to 9.5 KS]. Congestive heart failure persisting despite intensive medical treatment was present In 8 patients [56%], and was the most common indication for operation. Early operation was necessary in 5 of these patients [35%], because of failure to thrive and recurrent pulmonary infection. In one patient with TOF, frequent hypoxic spell prompted the necessity for early operation. In cases of VSD, TAP. VR, TOF, and coronary A-V fistula, Intracardiac repair was done with conventional cardiopulmonary bypass, chemical cold cardioplegia, and topical myocardial cooling. Deep hypothermic circulatory arrest with surface induced cooling, followed by core cooling and core rewarming, was employed .for better exposure in the cases of d-TGA and Taussing-Bing malformation. The results were however, not satisfactory. The overall mortality was 28 per cent. There were no deaths in the eight patients with VSD. The one with coronary A-V fistula survived. The other 5 cases all expired either on the table or immediately after operation. The non-fatal post-operative complications included low cardiac output, respiratory insufficiency, bleeding, and temporary A-V block. The causes of death were prolonged circulatory arrest time in d-TGA, complete A-V block and low cardiac output in TOF and Taussing-Bing malformation and prolonged bypass time and Inadequate correction in TAPVR.