• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3437-3443
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• 2013

The polymer insulators have been extensively used as an alternate material of ceramic insulators. However, when they are used in practical conditions, there are many problems of decreasing performance and shortening lifetime due to the exposures of degradation factors applied from the outdoor situations. Accordingly, the analysis of polymer degradations has been getting influential too late as one of important subjects for improvements of safety and reliability. Heat, water treatments are arbitrary simulated for finding out the initiations and processes of surface degradation on the polymer surface. Especially, this study is focused on the chemical changes properties. From the analysis of hydrophilic and hydrophobic molecular structures, final modeling of surface degradation is accomplished. We checked the contact angle depending on heat and moisturized accelerated degradation and ran an XPS analysis to check the mechanism change of the surface of the PCB polymer composite. The surface that had a tendency to attract moisture showed a decrease in the contact angle and generated a large amount of carboxyl($-COO^*$) radicals. The hydrophobized surface showed an increase in the contact angle and had a stable chemical composition constituted of the breakaway of oxygen radicals and the formation of double bond by carburization.

• Journal of Chest Surgery
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• v.30 no.3
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• pp.263-269
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• 1997

From April 1987 to May 1996, 13 infants underwent a Norwood operation for complex congenital heart diseases including hypoplastic left heart syndrome (n : 7), mitral stenosis with small VSD and subaortic stenosis (n : 1), mitral atresia with ventricular septal defect, coarctation of aorta, and subaortic stenosis (n = 1), interrupted aortic arch with ventricular septal defect and subaortic stenosis (n : 1), tricuspid atresia with transposition of the great arteries (n = 1), and complex double-inlet left ventricle (n : 2). All patients without hypoplastic left heart syndrome were associated wit hypoplasia of ascending aorta and arch. Age at operation ranged from 3 days to 8.7 months (mean 60.6 $\pm$ 71.6 days, median 39 days). The operative mortality( < 30 days) was 46% (6 patients). Late mortality was 15% (2 patients). All operative deaths occured during the Erst 24 hours after the operation as a result of cardiopulmonary bypass weaning failure (5 patients) and sudden hemodynamic instability postoperatively (1 patient). Late death was due to aspiration pneumonia in two cases. There are 5 long-term survivals (39%). Three of them have undergone a two-stage repair with a modified Fontan operation in two and total cavopulmonary shunt in one at 12, 17, 4.5 months after Norwood procedure with no mortality. Two patients have entered a three-stage repair strategy by undergoing a bidirectional cavopulmonary shunt at 3 and 5.5 months after initial operation with 1 operative death. The actuarial survival rate for all patients at the first-stage operation, including hospital deaths and ate death was 30.8% at 1 year. In conclusion, the operative mortality of Norwood operation was relatively high compared to other operation for major cardiac anomalies, continuing experience will lead to an improvement in result.

• Korean Journal of Plant Taxonomy
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• v.44 no.1
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• pp.22-32
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• 2014

The petal and sepal micromorphology of five species of Glechoma (Lamiaceae) was investigated to evaluate their taxonomic significance, and a molecular phylogeny using the sequences of internal transcribed spacers (ITS) regions of nuclear ribosomal DNA was carried out to resolve their phylogenetic relationships. Stomatal complexes were mostly found in the inner and outer part of the sepal from all investigated taxa, and the size length of the guard cell was variable among the taxa. Five types of trichomes (uni-cellular non-glandular trichome, multi-cellular non-glandular trichome, short-stalked capitate glandular trichome, long-stalked capitate glandular trichome, and peltate glandular trichome) were variable among the taxa as well as their distribution and density. In molecular phylogenetic studies, the genus Glechoma was composed of three geographically distinct major monophyletic groups (Europe-U.S.A., China-Korea, Japan). G. longituba in Korea and China formed well-supported monophyletic group. G. hederacea in Europe and U.S.A. formed a monophyletic and well-supported clade with G. sardoa, which are endemic species in Italy, with G. hirsuta falling as a sister to this clade. However, G. grandis did not form any phylogenetic relationships with the remaining taxa. The ITS analyses provided taxonomic boundaries of taxa in Glechoma although the petal and sepal micromorphological characters provided weak evidences of the systematic value. As further studies, incorporating more DNA regions to the matrix including other additional morphological analysis will be significant to provide clearer taxonomic structure in Glechoma.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1547-1550
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• 2002

MANET은 전형적인 무선 네트워킹과는 다른 새로운 무선 네트워킹 파라다임으로써 기존 유선 망의 하부 구조에 의존하지 않고 이동 호스트틀로만 구성된 네트워크이다. Ad Hoc망에서 통신을 하기 위해서는 출발지 노드에서 목적지 노드까지 데이터 전송을 위한 라우팅에 관한 문제이다. Ad Hoc망에서는 모든 단말기의 위치변화가 가능하기 때문에 경로설정에 어려움이 따른다. 노드간에 정보를 보내고자 할 때 노트가 인접한 상태가 아니면 정보를 직전 보낼 수 없고 여러 중간 노드들을 거쳐서 정보를 보내는 다중-홉 라우팅 방식을 사용해야 한다. 따라서 중간 노드들은 패킷 라우터의 역할을 해야하는데 무선 통신 자체가 좁은 대역폭과 한정된 채널을 가지고 전송 범위가 제한되는 문제가 있다. 또한 노트 자체의 이동성과 전력 소모 등으로 인한 이탈은 망 위상을 수시로 변화시키므로 노트간에 정보를 전송하는데 가장 종은 경로는 수시로 변경될 수 있으므로 많은 어려움이 따르게 된다. 본 논문에서는 이러한 문제의 해결방안으로 경로유지 과정에서 Ad Hoc망 내의 노드들은 이동성의 특성으로 인해 현재 사용되는 경로 보다 더 짧고 효율적인 경로가 발생하고 중간 노트가 이동 될 때 새로운 경로로 갱신하여 솔기없는 최적의 경로를 유지할 수 있는 방법을 제안한다. 제안 방법은 ZRP의 IERP에서 감청모드를 통하여 사공중인 경로보다 최적의 경로를 감지하여 새로운 경로로 갱신하는 방법과 중간 노드가 이동하여 경로가 깨진 경우 부분적으로 경로를 복구하는 방법을 제시하여 항상 최적화된 경로를 유지함으로써 Ad Hoc망의 위상변화에 대한 적응성을 높일 수 있도록 한다. SQL Server 2000 그리고 LSF를 이용하였다. 그리고 구현 환경과 구성요소에 대한 수행 화면을 보였다.ool)을 사용하더라도 단순 다중 쓰레드 모델보다 더 많은 수의 클라이언트를 수용할 수 있는 장점이 있다. 이러한 결과를 바탕으로 본 연구팀에서 수행중인 MoIM-Messge서버의 네트워크 모듈로 다중 쓰레드 소켓폴링 모델을 적용하였다.n rate compared with conventional face recognition algorithms. 아니라 실내에서도 발생하고 있었다. 정량한 8개 화합물 각각과 총 휘발성 유기화합물의 스피어만 상관계수는 벤젠을 제외하고는 모두 유의하였다. 이중 톨루엔과 크실렌은 총 휘발성 유기화합물과 좋은 상관성 (톨루엔 0.76, 크실렌, 0.87)을 나타내었다. 이 연구는 톨루엔과 크실렌이 총 휘발성 유기화합물의 좋은 지표를 사용될 있고, 톨루엔, 에틸벤젠, 크실렌 등 많은 휘발성 유기화합물의 발생원은 실외뿐 아니라 실내에도 있음을 나타내고 있다.>10)의 $[^{18}F]F_2$를 얻었다. 결론: $^{18}O(p,n)^{18}F$ 핵반응을 이용하여 친전자성 방사성동위원소 $[^{18}F]F_2$를 생산하였다. 표적 챔버는 알루미늄으로 제작하였으며 본 연구에서 연구된 $[^{18}F]F_2$가스는 친핵성 치환반응으로 방사성동위원소를 도입하기 어려운 다양한 방사성의 약품개발에 유용하게 이용될 수 있을 것이다.었으나 움직임 보정 후 영상을 이용하여 비교한 경우, 결합능 변화가 선조체 영역에서 국한되어 나타나며 그 유

• The Korean Journal of Financial Management
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• v.8 no.2
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• pp.209-255
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• 1991

This paper develops a simple model to explain the reasons why foreign acquirers pay significantly higher premiums for U.S. target firms than do U.S. buyers. We also provide empirical work on the valuation effect of foreign takeovers and the determinants of the wealth gains of U.S. target shareholders involved in foreign takeovers. The results indicate that target wealth gains are significantly higher in foreign takeovers than in domestic takeovers, after controlling for the wealth effects of payment method, acquisition type, tax status, size and time period of bids. This confirms the valuation effect of foreign takeovers. Furthermore, the results of cross-sectional regression analysis show that the variation in U.S. target wealth gains is explained by extra tax benefits stemming from double tax deductions for acquisition-related interest expenses incurred by foreign acquirers. These findings imply that differential taxation across tax jurisdictions is the main source of the valuation effect of foreign takeovers. In addition, we find that there exists a valuation effect of the nationality of the foreign acquirers. Japanese companies pay significantly higher premiums than do non-Japanese acquirers. The finding also indicates that competition among bidders increases the abnormal returns to U.S. target shareholders in foreign takeovers.

• Tuberculosis and Respiratory Diseases
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• v.46 no.3
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• pp.363-371
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• 1999

Background: Because of the widespread use and availability of agricultural insecticides, acute organophosphate poisoning as a suicide or an accident is becoming the most common type of poisoning and serious problem in Korea. The mortality of organophosphate poisoning varied from 10 to 86 percent. The cause of death was thought to be a combination of excessive bronchial secretion, bronchospasm, respiratory muscle paralysis and depression of respiratory center, summarily respiratory failure. We evaluated the respiratory complications in patients with acute organophosphate intoxication to determine the predisposing, factors to respiratory failure and to reduce the incidence of respiratory failure or mortality. Method: We conducted a retrospective study of 111 patients with the discharge diagnosis of organophosphate poisoning who were hospitalized at Yenugnam University Hospital during the 5 years. The diagnosis of organophosphate poisoning has based on the followings (1) a history of exposure to an organophosphate compounds. (2) the characteristic clinical signs and symptoms. (3) decrease in the cholinesterase activity in the serum. Results: Respiratory failure developed in 31(28%) of 111 patients with acute organophosphate poisoning. All cases of respiratory failure developed within 96 hours after poisoning and within 24 hours in 23 patients. The 80 patients who did not develop respiratory failure survived. In 31 patients with respiratory failure, 15(44%) patients were dead. The patients with respiratory failure had more severe poisoning, that is, the lower level of serum cholinesterase activity on arrival, the higher mean dosage of atropine administered within first 24 hours. In 16 patients with pneumonia, 14 patients developed respiratory failure. In 5 patients with cardiovascular collapse, 2 patients developed respiratory failure. There was no correlation to between age, sex, the use of pralidoxime and respiratory failure. The serum cholinesterase level in survivors at time of respiratory failure and weaning was $66.05{\pm}85.48U/L$, $441{\pm}167.49U/L$, respectively. Conclusion: All the respiratory failure complications of acute organophosphate poisoning occurred during the first 96 hours after exposure. The severity of poisoning and pneumonia were the predisposing factors to respiratory failure. Aggressive treatment and prevention of the above factors will reduce the incidence of respiratory failure.

• Journal of Chest Surgery
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• v.29 no.11
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• pp.1218-1222
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• 1996

The reported incidence of postcardiotomy cardiogenic shock not responding to conventional therapy is still 0.1 to 0.8%. For this group of patients, more aggressive form of circulatory support must be employed. Centrifugal pumps are a ventricular assist device most commonly used on this purpose, due to low cost and easy availability. Currently, however, clinical experience of centrifugal pumps as a ventricular assist device is rarely reported in Korea. From January 1992 to January 1996, 2986 patients underwent cardiac operations on cardiopulmonary bypass at Seoul National University Hospital. Refractory postcardiotomy cardiac failure requring ventricular support with a Biomedicus centrifugal pump developed in ten of these patients. There were eight men and two women, ranged in age from nine years to 77 years with a mean of 50$\pm$20 years. The primary surgical procedures consisted of isolated coronary revascularization in four patients, combined coronary revascularization and aortic valve replacement in two, aortic dissection repair in two, pulmonary embolectomy in one, and heart transplantation in one. Of the ten patients, five had left ventricular assistance, one had right ventricular assistance, and four had biventricular assistance. Duration of ventricular assistance ranged from 24 to 175 hours, with a mean of 76$\pm$51 hours. Seven patients were weaned from ventricular assistance, and four of them discharged. The causes of death for nonsurvivors were progressive cardiac failure in two patients and multiorgan failure, intractable ventricular fibrillation, irreversible brain injury, and mechanical problem, respectively, in the other four. Survival was not predicted by time on cardiopulmonary bypass, aortic cross-clamp time, or duration of ventricular support. Major complications included bleeding(7), renal failure(6), infection(3) and neurologic complication(2). These results indicate that a centrifugal pump can provide reasonably satisfactory short-term circulatory support.

• Clinical and Experimental Pediatrics
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• v.48 no.7
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• pp.737-744
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• 2005

Purpose : Infants and children with cardiovascular diseases often present with respiratory symptoms. However, missed or delayed evaluation for potential airway problem may complicate overall prognosis. The aim of this study is to determine the clinical characteristics of these patients and explore the cause of airway problem. Methods : We reviewed the medical records of 64 patients(M : F=33:31, mean age : $6.3{\pm}7.5$ months) whose airway problems were proven by computed tomography or bronchoscopy in perioperative periods at the Asan Medical Center from January 1997 to June 2004. Patients were divided into two groups based on the duration of ventilator care : ${\leq}7$ days(group 1 : 23 cases, M : F=10 : 13) and >7 days(group 2 : 41 cases, M : F=23 : 18). Results : The patients in group 2 significantly developed more post-operative respiratory symptoms than group 1(P<0.001) and had more airway problems including extrinsic obstruction, intrinsic anomaly, and combined problem than group 1 although not significantly different(P=0.082). Among underlying diseases, the most common diseases were vascular anomaly(26.2 percent) and aortic arch anomaly(26.2 percent) in group 1 and pulmonary atresia with ventricular septal defect(22.4 percent) in group 2. The most frequent respiratory symptoms were recurrent wheezing pre-operatively and failure of ventilator weaning post-operatively. The major types of airway anomaly were tracheomalacia and tracheal stenosis(in each case 18.2 percent). Nineteen patients with persistent airway problems underwent aortopexy or other vascular correction. Of the 19 patients, 13(68.4 percent) were improved, but 2 failed in weaning ventilator and 4 died of non-airway problems. Conclusion : Early evaluation and treatment for potential airway problems may affect natural or surgical prognosis in patients with cardiovascular diseases presenting with respiratory symptoms.

• Clinical and Experimental Pediatrics
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• v.48 no.10
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• pp.1096-1101
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• 2005

Purpose : Recently, early surfactant replacement and tidal volume based gentle ventilation has been a fundamental treatment of respiratory distress syndrome(RDS). The aims of this study were to survey the changes in ventilator care duration and rate of complication in RDS groups. Methods : We performed a retrospective study of 255 newborn infants less than 1,500 g admitted to the neonatal intensive care unit(NICU) and discharged from January 1999 to December 2003. 141 of 255 newborn infants were RDS groups that required invasive management, such as endotracheal intubation, surfactant replacement and assisted ventilation. We analyzed epidemiologic data to study the changes in ventilator care duration and outcome of RDS groups. Results : Of 141 RDS groups, 135 were mild to moderate RDS groups and only 6 were severe RDS groups. 24(17.8%) of 135 mild to moderate RDS groups and 3(50%) of 6 severe RDS groups were antenatal no use of maternal dexamethasone. 127(90.1%) of 141 RDS groups underwent replacement of surfactant during 3 hours after birth. 121(85.9%) weaned within 48 hours. Conclusion : Our study shows a decreased frequency of severe RDS by a antenatal use of maternal dexamethasone and decreased duration of ventilator care by early surfactant replacement and gentle ventilation.