• Journal of Chest Surgery
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• v.11 no.4
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• pp.535-540
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• 1978

Between January 1974 and November 1978, 23 cases of double valve replacement were done in the Department of Thoracic Surgery, Seoul National university Hospital. All had symptoms of rheumatic valvular heart disease and belonged to functional class III or IV according to NYHA classification. Among 23 cases, mitral and aortic valves were replaced in 14, and mitral and tricuspid valves in 9 cases. Six operative deaths [26%] and 4 late deaths [23%] were found. In the former group 5 and in latter one operative death were noted. Main cause of operative death was low cardiac output syndrome due to myocardial failure. Among 4 late deaths, 2 were caused by thromboembolism, one by bacterial endocarditis, and one by arrhythmia.

• Journal of Chest Surgery
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• v.19 no.1
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• pp.83-91
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• 1986

The Carpentier-Edwards porcine xenograft valve was used in 21 patients at Seoul National University Hospital during the period between 1977 and 1979. Twenty-four Carpentier-Edwards valves were implanted along with 2 others. Three patients died within 30 days of operation, an operative mortality rate of 14.3%. Eighteen early survivors were followed up for a total 67.5 patient-years [mean, 45.0$\pm$32.0 months]. There were 2 late deaths with a linealized late mortality rate of 2.96%/patient-year; one died from cerebral bleeding [1.48% bleeding/patient-year] and the other from prosthetic valve endocarditis [1, 48% endocarditis/patient-year]. There was no case of thromboembolism. Two patients developed mitral regurgitation [2.96% failure/patient-year]. Symptomatic improvement was excellent. The actuarial survival rate and the probability of freedom from overall valve failure were 75.3$\pm$9.6% and 80.7$\pm$12.9% at 9 years after surgery respectively. During the period from October, 1968, through June, 1985, 1, 190 substitute heart valves were used in a total of 967 patients at Seoul National University Hospital; of which, 90.9% were either porcine aortic or bovine pericardial xenograft valves. For the evaluation of the xenograft tissue valves, the consecutive patients with lonescu-Shiley valve in the mitral, aortic and both positions, Angell-Shiley valve and Carpentier-Edwards valve were recently studied on the clinical ground. They were 531 patients, and 643 xenograft valves were used. The operative mortality rate was 6.97% and a linealized late mortality rate 2.94%/patient-year. A total of 490 early survivors were followed up for 917.6 patient-years [mean, 22.5 months], and 70% of patients completed the follow-up. The linealized incidences of complications were: 2.29% emboli/patient-year, 1.98% bleeding/patient-year, 1.20% endocarditis/patient-year, and 3.49% failure/patient-year. These clinical resutls are fully comparable with those in the major reports. The durability of the glutaraldehydepreserved xenograft heart valves remains as a great concern and a continuing debate, expecially for the group of patients in the pediatric age. The need of more durable material for the improved tissue valves was also discussed.

• Journal of English Language & Literature
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• v.64 no.3
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• pp.403-414
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• 2018

This paper suggests a different reading of James Joyce's "Araby" by offering the video game as a lens through which we can reimagine the story. Understanding the unnamed boy's journey to the Araby bazaar as a fetch quest, this paper focuses on the boy's failure to complete this quest. As soon as the boy promises Mangan's sister something from Araby, his fetch quest begins. In order to complete the quest, the boy must successfully perform three sub-quests: get money from his uncle as early as he can, get on the train for the Araby bazaar on time, and pass through the sixpenny entrance at the bazaar. However, because his uncle comes home late, the boy fails to get the money early, and that sets off the subsequent failures. The boy then takes the train late and arrives at the bazaar so late that he feels he must go through any entrance. So he walks through the adult entrance by mistake. As a result, he does not have enough money to buy a gift, failing the larger quest. But, regardless of this failure, the boy can try these quests as many as he wants until he finally succeeds in completing them. But no matter how the boy tries to accomplish these subquests, he is doomed to fail them because he cannot make his uncle come home early. The more he tries his quest, the more bitterly he realizes that he will ultimately fail. In this respect, the boy's "anguish and anger" should be understood as his epiphany: the re-playability of the game is possible, but all the replays lead to the same failure: losing the game. In this regard, reading Joyce's "Araby" is much like playing a video game.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.980-989
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• 1989

The Hancock porcine xenograft valves had been used in Seoul National University Hospital, mainly because of their antithrombogenicity despite of the predicted failure, from March 1976 to April 1984, and a total and consecutive 163 patients were retrospectively studied for late results with the special stress on the structural failure. The hospital mortality rate [within 30 days] was 6.1 %, and the 153 early survivors were followed up for a total of 822.9 patient-years [p-y][Mean * SD 5.38 * 3.02 years]. The linealized late mortality was 1.823%/p-y. Four major complications related to the Hancock valve were: 1.822% thromboembolism/p-y; 0.729 % bleeding/p-y; 0.972% endocarditis/p-y; 3.646% overall valve failure/p-y and 2.187 % primary tissue failure [PTF]/p-y. The actuarial survival rates at 5 and 10 years were 94.90 * 1.89% and 80.58 * 5.21 %; and the probabilities of freedom from thromboembolism at 5 and 10 years were 90.93 * 2.63% and 83.35 * 7.64 9o respectively. The probabilities from PTF at 5, 10 and 12 years were 98.02 * 1.39%, 60.62 * 8.89% and 49.60 * 12.34 %. One hundred-eighteen patients [72.4%] had single MVR [age, 34.0 * 10.9 years] with the operative mortality rate of 4.2%; and 113 early survivors were followed up for a total 616.4 patient-years[5.46 * 2.96 years]. The late mortality rate was 1.460 %/p-y. The major complications were: 1.622 % thromboembolism /p-y; 0.487% bleeding/p-y; 0.649 % endocarditis/p-y; 2.920% primary valve failure/p y and 1.785% PTF/p-y. The actuarial survival rates were 97.08 * 1.67%[at 5 years] and 81.27 * 6.64%[at 10 years], and the probabilities of freedom from thromboembolism 92.44 * 2.76 %[at 5 years] and 80.89 * 11.08%[at 10 years]. The probabilities of freedom from PTF at 5 and 10 years were 98 70 * 1.29% and 65.59 * 9.78% respectively. The mean age of 11 patients of PTF was 25.7 * 8.8 years and the valve extraction period 7.16 * 1.45 years. Failure of bioprosthetic xenograft valves are reportedly known to occur earlier in young patients in an accelerated fashion. The study with two groups divided into the cumulative younger and the cumulative older patients according to the age limits of 5-year interval strongly suggested these tendency. Although PTF began to occur past postoperative 5 years and the probabilities of freedom from PTF increased as the age limits raised and the number of patients increased in the cumulative younger patients while they decreased as the age limits lowered and the number of patients increased in the cumulative older patients, the definite age limits from which the Hancock valve can be safely recommended could not be obtained. From the results, the Hancock valves are contraindicated in patients younger than 20 to 25 years and may be safely recommended in patients older than 45 years as a tentative conclusion. Further longitudinal study may define these age factors.

• International journal of thyroidology
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• v.11 no.2
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• pp.130-136
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• 2018

Background and Objectives: Intraoperative neural monitoring (IONM) of recurrent laryngeal nerve (RLN) in thyroid surgery has been employed worldwide to identify and preserve the nerve as an adjunct to visual identification. The aims of this study was to evaluate the efficacy of IONM and difficulties in the learning curve. Materials and Methods: We studied 63 patients who underwent thyroidectomy with IONM during last 2 years. The standard IONM procedure was performed using NIM 3.0 or C2 Nerve Monitoring System. Patients were divided into two chronological groups based on the success rate of IONM (33 cases in the early period and 30 cases in the late period), and the outcomes were compared between the two groups. Results: Of 63 patients, 32 underwent total thyroidectomy and 31 thyroid lobectomy. Failure of IONM occurred in 9 cases: 8 cases in the early period and 1 case in the late period. Loss of signal occurred in 8 nerves of 82 nerves at risk. The positive predictive value increased from 16.7% in the early period to 50% in the late period. The mean amplitude of the late period was higher than that of the early period (p<0.001). Conclusion: IONM in thyroid surgery is effective to preserve the RLN and to predict postoperative nerve function. However, failure of IONM and high false positive rate can occur in the learning curve, and the learning curve was about 30 cases based on the results of this study.

• Journal of Korean Society for Quality Management
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• v.17 no.2
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• pp.17-26
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• 1989

This paper is concerned with forecasting the existing number of errors in the computer software and optimizing the stopping time of the software test based upon the forecasted number of errors. The most commonly used models have assessed software reliability under the assumption that the software failure late is proportional to the current fault content of the software but invariant to time since software faults are independents of others and equally likely to cause a failure during testing. In practice, it has been observed that in many situations, the failure rate decrease. Hence, this paper proposes a mathematical model to describe testing situations where the failure rate of software limearly decreases proportional to testing time. The least square method is used to estimate parameters of the mathematical model. A cost model to optimize the software testing time is also proposed. In this cost mode two cost factors are considered. The first cost is to test execution cost directly proportional to test time and the second cost is the failure cost incurred after delivery of the software to user. The failure cost is assumed to be proportional to the number of errors remained in the software at the test stopping time. The optimal stopping time is determined to minimize the total cost, which is the sum of test execution cast and the failure cost. A numerical example is solved to illustrate the proposed procedure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.159-166
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• 2008

In this paper, we proposed an algorithm to solve the problem that can't maintain hop synchronization using only early-late gate tracking loop due to the drift of geo-stationary satellite in frequency hopping satellite communication system. When the signal is transferred to downlink through DRT(Dehop-Rebop Transponder), the problem with synchronization loss is occurred periodically when using only early-late gate tracking loop, because of energy loss in each side portion of hop due to orbital variation of the satellite. To solve this problem, we have developed Anti-Shrink synchronization tracking algorithm which uses the prediction value of transmission timing and the structure of inner-outer gate instead of early-late gate with the ranging information. Through simulations, we showed that the performance of the Anti-Shrink algorithm is better than that of simple inner-outer energy ratio algorithm and similar to that of conventional early-late tracking loop algorithm with ranging information. No synchronization failure in the proposed algorithm was occurred because of less energy loss and robustness without the ranging information.

• Journal of Chest Surgery
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• v.29 no.2
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• pp.164-170
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• 1996

From January 1986 to June 1993, 12 patients Aad required reoperation: 9 had undergone mitral and 3 aortic valve replacement. Five were male and 7 female, and ages ranged from 29 to 61 years. Replacement of the prosthetic heart valve was performed at a mean interval of 98 $\pm$ 1 months after the Hrst operation. In aortic valve replacement patients the mean interval was 115 $\pm$ 2 months and in mitral valve replacement patients 98 $\pm$ 4 months. Primary tissue failure was the most frequent reason of replacement (10 patients) followed by valve thrombosis (1 patient) and prophylactic replacement (1 patient) in order. The most pronounced pathology of the failed prosthetic heart valves seen in the primary tissue failure group was calcification, perforation, shrinkage and tearing of the cusps. There was one early operative death (8.3%) due to intractable low cardiac output and acute renal failure. Eleven early survivors had successful operative results and there was no late death.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.15 no.1
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• pp.9-17
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• 2015

Glycogen storage disease (GSD) type Ia is rare inborn metabolic disorder, caused by glucose-6-phosphatase deficiency. It characterized by hepatomegaly, hypoglycemia, lactic acidosis, hypertriglyceridemia, and hyperuricemia and it is usually manifested in the infantile period. In addition, it is also associated with growth failure, pubertal delay, anemia, platelet dysfunction, osteopenia, and pulmonary hypertension. Hepatocellular adenoma and renal dysfunction are frequent late complications. Delayed diagnosis and inappropriate therapy lead to many complications such as growth failure, osteoporosis, refractory gout, renal failure, hepatocellular carcinoma (HCC), and pulmonary hypertension. Here, two Korean sisters diagnosed with GSD Ia, aged 33 and 36 respectively, were described and compared to recent articles about four adults with late diagnosis of GSD Ia. One sister had typical manifestations of GSD Ia including short stature (height, 145 cm), multiple hepatic adenoma, chronic kidney disease stage IV, and severe osteoporosis, whereas the older sister had normal stature (162 cm), one tiny hepatic nodule, and normal renal function. Direct sequencing of G6PC in two sisters identified a homozygous splicing mutation, c.645G>T, which is a prevalent mutation in Korea. Interestingly, our cases and four adults from recent reports had asymptomatic mild hypoglycemia and various manifestations including renal failure, HCC, fatty liver, or uncontrolled hyperlipidemia. These adult cases represent not only heterogenous phenotype to genotype within family members with GSD Ia but also long-term complications such as gouty arthritis, renal failure, and osteoporosis in untreated adult GSD Ia patients. In addition, lactic academia and hypertriglyceridemia are good markers of GSD Ia to distinguish from metabolic disease.

• Journal of Periodontal and Implant Science
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• v.39 no.sup2
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• pp.205-212
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• 2009

Purpose: The aim of this retrospective study was to compare the survival rate of oxidized titanium implants and sandblasted large-grit acid etched implants in soft bone. Methods: 201 oxidized titanium implants were inserted in 84 patients between May 1999 and May 2004. 120 sandblasted large-grit acid etched implants were inserted in 74 patients between December 2000 and May 2004. The patients were followed-up 0${\sim}$5 years in ITI group or 0${\sim}$6 years in BRA group, respectively. The following information was collected from the patient records: age, gender, systemic disease, implant type, number, length and diameter of the implants, their location in the jaws, bone quantity, the number of failed implants, the causes of failure, and advanced surgery for bone augmentation. Results: In the oxidized titanium implants, 8 implants showed early failure, and 1 implant showed late failure, respectively. The cumulative survival rate was 95.48%. In the sandblasted large-grit acid etched implants, 1 implant showed late failure and cumulative survival rate was 99.10%. The cumulative survival rate and the survival rates in the case of the advanced procedure during the implant placement were not significantly different in both groups. Conclusions: Oxidized titanium implants and sandblasted large-grit acid etched implants can be used successfully in soft bone regardless of the surgical methods used during the implant placement. (J Korean Acad Periodontol 2009;39:205-212)