• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.121-122
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• 2017

ITER AC/DC 컨버터(Converter)는 핵융합 발생을 위해 토카막의 초전도코일에 제어된 전류를 공급하여 플라즈마 발생, 형상 유지, 소멸하는 기능을 한다. 만일 컨버터 또는 초전도코일에 이상이 발생하면 즉시 보호동작이 실행되어야 한다. 이를 위해 설계된 F-LIC(Fast Local Interlock Controller)은 즉시 작동하여 Bypass 및 Make Switch 트리거, 차단기 작동 등을 순차적으로 수행한다. ITER Interlock System의 기기는 중요성이 고려되어 높은 신뢰도가 요구된다. 본 논문에서는 F-LIC 회로분석과 Telcordia SR-332 Standard에 의한 부품고장률 산출방법을 사용하여 FMEDA를 분석하고, 이를 통하여 회로구성 부품의 고장이 미치는 영향과 F-LIC 제어모듈의 SIL-2 등급의 적합성을 분석하였다.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1456-1458
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• 1999

As the system reliability of power supply is highly increased, we need distribution maintenance techniques without any power interruption. To meet such an increasing demand, a groat deal of hot line work on the high voltage overhead distribution lines has been carried out. In this regard, Hot line work techniques has being applied widely. However, hot line work techniques can not cover all kinds of work without interruption. To cope with those problems, the temporary power supply work technique such as bypass cable truck technique, temporary switch technique and mobile transformer technique was developed and applied. This paper presents the most optimal method according to distribution work contents through the comparison and analysis the characteristis and problems of the existing various work techniques. Also this paper suggested the countermeasers of the prsent problems.

• Journal of Power Electronics
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• v.15 no.4
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• pp.920-928
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• 2015

Transformerless solar inverters have a higher efficiency than those with an isolation link. However, they suffer from a leakage current issue. This paper proposes a family of single phase six-switch transformerless inverter topologies with an ac bypass circuit to solve the leakage current problem. These circuits embed two unidirectional freewheeling current units into the midpoint of a full bridge inverter, to obtain a freewheeling current path, which separates the solar panel from the grid in the freewheeling state. The freewheeling current path contains significantly fewer devices and poor performance body diodes are not involved, leading to a higher efficiency. Meanwhile, it is not necessary to add a voltage balancing control method when compared with the half bridge inverter. Simulation and experiments are provided to validate the proposed topologies.

• Journal of Chest Surgery
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• v.26 no.3
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• pp.180-185
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• 1993

From February 1982 to December 1991, 49 neonates and 105 infants in less than 3 months of age underwent open heart surgery in Seoul National University Hospital. There were 98 males and 56 females, and their mean ages were 16 days in neonatal group and 67 days in early infant group. Their body weight and height were less than 3 percentile of normal developmental pattern. In order of decreasing incidence, the corrected conditions included Transposition of great arteries with or without ventricular septal defect [43], isolated ventricular septal defect [34], Total anomalous pulmonary venous return [21], Pulmonary atresia with intact ventricular septum [9] and others [47]. Various corrective or palliative procedures were performed on these patients; Arterial switch operation [36], patch closure for ventricular septal defect [34], Repair of total anomalous pulmonary venous return [21], RVOT reconstruction for congenital anomalies with compromised right ventricular outflow tract [17]. Profound hypothermia and circulatory arrest were used in 94 patients [ 61% ]: 42 patients [ 85.7% ] for neonatal group and 52 patients [ 49.5% ] for early infant group. The durations of circulatory interruption were within the safe margin according to the corresponding body temperature in most cases [ 84% ]. The hospital mortality was 36.4% ; 44.9% in neonatal group and 32.4% in infant group 1 to 3 months of age. The mortality was higher in cyanotic patients [ 46.6% ], in those who underwent palliative procedures [ 57.8% ], in patients whose circulatory arrest time was longer than safe periods [ 60% 0] and in patients who had long periods of cardiopulmonary bypss and aortic crossclamping. In conclusion, there has been increasing incidence of open heart surgery in neonates and early infants in recent years and the technique of deep hypothermia and circulatory arrest was applied in most of these patients, and the mortality was higher in cyanotic neonates who underwent palliative procedures and who had long cardiopulmonary bypass , aortic cross-clamping and circulatory arrest.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.5 s.335
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• pp.15-22
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• 2005

This paper proposes an efficient structure which is able to perform self-detection and self-repair for faults in a digital system by imitating the structure of living beings. The self-repair system is composed of artificial cells, which have homogeneous structures in the two-dimension, and spare cells. An artificial cell is composed of a logic block based on multiplexers, and a genome block, which controls the logic block. The cell is designed using DCVSL (differential cascode voltage switch logic) structure to self-detect faults. If a fault occurs in an artificial cell, it is self-detected by the DCVSL. Then the artificial cells which belong to the column are disabled and reconfigured using both neighbour cells and spare cells to be repaired. A self-repairable 2-bit up/down counter has been fabricated using Hynix $0.35{\mu}m$ technology with $1.14{\times}0.99mm^2$ core area and verified through the circuit simulation and chip test.

• Journal of Chest Surgery
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• v.44 no.2
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• pp.115-122
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• 2011

Background: The intramural coronary artery has been known as a risk factor for early death after an arterial switch operation (ASO). We reviewed the morphological characteristics and evaluated the early and mid-term results of ASO for patients with an intramural coronary artery. Materials and Methods: From March 1994 to September 15th 2010, 158 patients underwent ASO at Dong-A and Pusan National University Hospitals for repair of transposition of the great arteries and double outlet right ventricle. Among these patients, 14 patients (8.9%) had an intramural coronary artery. Mean age at operation was $13.4{\pm}10.2$ days (4 to 39 days) and mean body weight was $3.48{\pm}0.33$ kg (2.88 to 3.88 kg). All patients except one were male. Eight patients had TGA/IVS and 4 patients had an aortic arch anomaly. Two patients (14.3%) had side-by-side great artery relation, of whom one had an intramural right coronary artery and the other had an intramural left anterior descending coronary artery. Twelve patients had anterior-posterior relation, all of whom had an intramural left coronary artery (LCA). The aortocoronary flap technique was used in coronary transfer in 8 patients, of whom one patient required a switch to the individual coronary button technique 2 days after operation because of myocardial ischemia. An individual coronary button implantation technique was adopted in 6, of whom 2 patients required left subclavian artery free graft to LCA during the same operation due to LCA injury during coronary button mobilization and LCA torsion. Results: There was 1 operative death (7.1%), which occurred in the first patient in our series. This patient underwent an aortocoronary flap procedure for coronary transfer combining aortic arch repair. Overall operative mortality for 144 patients without an intramural coronary artery was 13.2% (19/144). There was no statistical difference in operative mortality between the patients with and without an intramural coronary artery (p>0.1). There was no late death. The mean follow-up duration was $52.1{\pm}43.0$ months (0.5 to 132 months). One patient who had a subclavian artery free graft required LCA stenting 6.5 years after surgery for LCA anastomotic site stenosis. No other surviving patient needed any intervention for coronary problems. All patients had normal ventricular function at latest echocardiography and were in NYHA class 1. Conclusion: The arterial switch operation in Transposition of Great Arteries or Double Outlet Right Ventricle patients with intramural coronary can be performed with low mortality; however, there is a high incidence of intraoperative or postoperative coronary problems, which can be managed with conversion to the individual coronary button technique and a bypass procedure using a left subclavian free graft. Both aortocoronary flap and individual coronary button implantation techniques for coronary transfer have excellent mid-term results.

• Journal of Chest Surgery
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• v.36 no.8
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• pp.566-575
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• 2003

We reviewed our 18-year surgical experience of biventricular repair for double-outlet right ventricle. Material and Method: One hundred twelve consecutive patients (80 males and 32 females) who underwent biventricular repair for double-outlet right ventricle between May 1986 and September 2002 were included. We assessed risk factors for early mortality and reoperation. Reoperation-free survival rate and actual survival rate were analysed. Result: Most common type of ventricular septal defect was subaortic (n=58, 52%) and non-committed type was second most common (n=32, 29%). Four different surgical methods were used: intraventricular baffle repair (n=71 , 63%): right ventricle to pulmonary ariery conduit interposition or REV with left ventricle to aorta baffle repair (n=24, 21 .4%): arierial switch operation with left ventricle to pulmonary artery baffle (n=14, 12.5%): Senning atrial switch operation with left ventricle to pulmonary artery baffle (n=3, 2.7%). Thirty four patients(30%) underwent palliative procedures before definite repair. Twenty three patients (21%) required reoperations. There were 12 (10.7%) early deaths and 4 late deaths. Age younger than 3 months at repair (p=0.003), cardiopulmonary bypass and aortic cross clamp time (p=0.015, p=0.067), type of operation (arterial switch operation) (p <0.001) and type of ventricular septal defect (subpulmonic type) (p=0.002) were revealed as risk factors for early death in univariate analysis, while age under 3 months was the only significant risk factor in multivariate analysis. Patients younger than 1 year of age (p=0.02), pulmonary artery angioplasty at definitive repair (p=0.024), type of ventricular septal defect (non-committed) (p=0.001), type of operation (right ventricle to pulmonary artery conduit interposition and REV operation) (p=0.028, p=0.017) were risk factors for reoperation in univariate analysis but there was no significant risk factor in multivariate analysis. Follow-up was available on 91 survivals with a mean duration of 110.8$\pm$56.4 (2~201) months. 5, 10 and 15 year survival rates were 86.5%, 85% and 85% and reoperation free survival were 85%, 71.5%, 70%. Conclusion: Age under 3 months at repair, subpulmonic ventricular septal defect and arterial switch operation were significant risk factors for early mortality. Patients with non-committed ventricular septal defect and who underwent conduit interposition or REV operation were risk factors for reoperation. With careful attention to chose best timing and surgical approach depending on morphologic characteristics, biventricular repair for double outlet right ventricle can be achieved with good long-term outcome.

• Clinical and Experimental Pediatrics
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• v.50 no.7
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• pp.665-671
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• 2007

Purpose : The purpose of this study was to investigate the clinical features and outcome in newborns undergoing cardiac surgery. Methods : Eighty two neonates underwent heart surgery for congenital heart defect at Kyungpook National University Hospital between March 2000 and February 2006. Patient characteristics (sex, age, diagnosis), pre-operative conditions, operation type, postoperative complications and mortality were reviewed retrospectively. Results : In 82 patients, 41 (50%) were male. The mean age and weight at operation were 12 days and 3.2 kg, respectively. The common cardiac anomalies were complete transposition of the great arteries (TGA), Tetralogy of Fallot (TOF), pulmonary atresia with intact ventricular septum, and single ventricle variants. Fifty seven operations were performed with cardiopulmonary bypass and corrective surgery was done on 54 patients. Arterial switch operation and modified Blalock-Taussig shunt were most frequently performed as corrective and palliative operations, respectively. The early hospital mortality rate was 7%; the late mortality was 3.9%. Complications were acute renal insufficiency, delayed sternal closure, wound infection, arrhythmia, and brain hemorrhage. Conclusion : During the last 6 years, the outcomes of cardiac surgery for congenital heart defects in neonates improved by progress in perioperative, anaesthetic, surgical, and postoperative care.

• Journal of Chest Surgery
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• v.38 no.3 s.248
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• pp.181-190
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• 2005

The results of biventricular repair for double outlet right ventricle have been improved in recent series. We studied the surgical and long term results for total correction of double outlet right ventricle by the type of ventricular septal defect. Material and Method: Between November 1979 and December 2003, 126 patients had biventricular repair for double outlet right ventricle. The mean age was 1.8 years (range 1$\~$44) and 86 patients ($68.3\%$) were male. We classified and studied this disease by the type of VSD. Result: The locations of VSD were subaortic in 79 ($62.7\%$), subpulmonary in 17 ($13.5\%$), doubly committed in 16 ($12.7\%$) and noncommitted in 14 ($11.1\%$). 28 patients had palliative operation before total correction and the mean interval to total correction was 41.0$\pm$45.1 months. The methods of total correction were intraventricular baffling in 37 ($29.4\%$), intraventricular baffling with patch enlargement of right ventricular outflow tract in 49 ($38.9\%$), intraventricular baffling with Rastelli procedure in 15 ($11.9\%$), arterial switch operation in 8 ($6.3\%$) and REV procedure in 4 ($3.2\%$), etc. Hospital mortality rate was $10.3\%$ (13 patients) and 25 reoperations were performed in 24 patients ($19.0\%$). The risk factors for hospital mortality and reoperation were cardiopulmonary bypass time (p=0.020) and previous palliative operation (p=0.013), respectively. Follow up was possible in 98 patients and mean follow up period was 118.9$\pm$70.7 months. The percent survival and survival for freedom from reoperation at 15 years were $82.5\%$ and $66.7\%$, respectively. The survival rate was significantly lower (p=0.003) in transposition of great artery type and remote type than in simple ventricular septal defect type and tetralogy of Fallot type, but there was no statistical differences in survival rate for freedom from reoperation. Conclusion: It is thought to be that acceptible surgical and long term results can be obtained with application of appropriate methods of repair for double outlet right ventricle.

• Journal of Chest Surgery
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• v.29 no.8
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• pp.828-835
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• 1996

From January 1993 to April 1995, 27 neonates (under age of 30 days underwent open heart surgery in the Department of Thoracic and Cardiovascular Surgery, Dong-A Medical Center. Mean age and weight were 12.1 days(2days∼306ays) and 3.29 kg(2.6kg∼4.1 kg) respectively. Cardiac anomalies were simple complete transposition of great arteries(TGA) in 11 neonates, TGA with coarctation of aorta(COA) in 1 , total anomalous pulmonary venous connection(TAPVC) in 5, double inlet right ventricle with TAPVC in 1, interrupted aortic arch(IAA) with ventricular septal defect(VSD) in 3, pulmonary atresia(PA) with intact ventricular septum(IVS) in 3, pulmonary stenosis with IVS in 1, Taussig-Bing anomaly with IAA in 1, and hypoplastic left heart syndrome(HLHS) in 1 . Postoperative complications were myocardial and/or pulmonary edema which caused open sternum in 13 patients(54.2%), acute renal failure( RF) in 10(37.0%), Intractable low cardiac output syndrome (LCOS) including weaning failure from cardiopulmonary bypass in 7(25.9%), bronchopulmonary dysplasia in 1, wound infection in 1, and paroxysmal supraventricular tachycardia in 1. Nine of 13 patients with postoperative open sternum were recovered with delayed sternal closure, and seven of 10 patients survived postoperative ARF with peritoneal dialysis. There were 8 operative deaths(29.6%): 3 in the patients with simple complete TGA, 1 In TCA with COA, 1 in PA with IVS, 1 in Taussig-Bing anomaly with IAA, 1 in DIRV with TAPVC, and 1 in HLHS. One late death occurred after arterial switch operation in simple TGA. The mosts common cause of death was low cardiac output syndrome. Our initial experience of open heart surgery in neonates showed high operative mortality and morbidity, especially in complex anomalies.