• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.21-27
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• 2003

분산컴퓨팅, 다자간 협업, 대용량 고품질의 컨텐츠 교환을 지원하는 P2P는 차세대 인터넷의 핵심 어플리케이션이 될 것이다. 본래 인터넷의 근본이었던 IP 라우팅도 P2P 방식이었다. 장비가 다양해지고, PC가 증가하게 됨에 따라 동적 IP를 사용하거나, 하나의 IP를 여러 사람이 공유하여 사용하는 복잡한 방식을 취하기 시작했다. 그러나 새로운 IP 주소들이 충분히 공급될 수 있다면, 하나의 장치 당 하나의 주소 체제가 다시 각광을 받게 될 것이고, 지금처럼 불규칙적인 동적 IP 주소를 활용하지 않아도 될 것이다. 그런 의미에서 IPv6는 풍부한 주소자원을 각 단말에 부여할 수 있어, IPv16 기반의 P2P 구축은 P2P의 성능을 최적화하는 방법이 될 것이다. 현재 P2P는 콘텐츠 공유 및 전달, 네트워크/장치(하드디스크, CPU) 리소스 공유, 다자간 원격협업, 검색, 호스팅 및 프로젝트 관리 등 다양한 방법으로 활용되고 있다. 2000년경부터 대두되기 시작한 P2P 애플리케이션은 지난 2년 동안 급속하게 늘어났으며, 특히 인터넷 사용자들은 컨텐츠를 공유/전달할 목적으로 P2P를 많이 사용하고있다. 그러나 컨텐츠의 공유에 있어 MP3, 동영상, 이미지의 전달 및 공유에 그치고 있어, P2P를 기업 환경에서 지식공유 및 전달을 위한 시스템으로 활용하는 경우는 아직 미약하다. 그러므로 본 논문에서는 조직 내에서 정보활용 능력을 제고하기 위한 방안으로 P2P 시스템을 정보 공유 시스템으로 팔용하고, P2P의 성능을 최적화 할 수 있는 IPv6 기반의 개발 방안을 제안하고자 한다. 본 IPv6 기반의 정보 공유 P2P는 IPv6 전문가 그룹을 통해 시범적으로 적응하는 것으로 시작해, 학교 및 연구소를 통한 정보지식 공유 그리고 기업 정보화 솔루션으로 활용 될 수 있다.을 제시한다. 이렇게 함으로써 최대한 고객 납기를 만족하도록 계획을 수립할 수 있게 된다. 본 논문에서 제시하는 계획 모델을 사용함으로써 고객 주문에 대한 대응력을 높일 수 있고, 계획의 투명성으로 인한 전체 공급망의Bullwhip effect를 감소시킬 수 있는 장점이 있다. 동시에 이것은 향후 e-Business 시스템 구축을 위한 기본 인프라 역할을 수행할 수 있게 된다. 많았고 년도에 따른 변화는 보이지 않았다. 스키손상의 발생빈도는 초기에 비하여 점차 감소하는 경향을 보였으며, 손상의 특성도 부위별, 연령별로 다양한 변화를 나타내었다.해가능성을 가진 균이 상당수 검출되므로 원료의 수송, 김치의 제조 및 유통과정에서 병원균에 대한 오염방지에 유의하여야 할 것이다. 확인할 수 있었다. 이상의 결과에 의하면 고농도의 유기물이 함유된 음식물쓰레기는 Hybrid Anaerobic Reactor (HAR)를 이용하여 HRT 30일 정도에서 충분히 직접 혐기성처리가 가능하며, 이때 발생된 $CH_{4}$를 회수하여 이용하면 대체에너지원으로 활용 가치가 높은 것으로 판단된다./207), $99.2\%$(238/240), $98.5\%$(133/135) 및 $100\%$ (313)였다. 각각 두 개의 요골동맥과 우내흉동맥에서 부분협착이나 경쟁혈류가 관찰되었다. 결론: 동맥 도관만을 이용한 Off pump CABG를 시행하여 감염의 위험성을 증가시키지 않으면서 영구적인 신경학적 합병증을 일으키지 않았고 좋은 혈관 개존율을 보여주었다. 따라서 동맥 도관을 이용한 Off pump CABG는 관상동맥의 협착의 정도에 따라 효율적으로 시행 시 좋은 임상결과를 얻을 수 있을 것으로 생각된다.였다. 그러나 심근 기능이나

• Clinical and Experimental Pediatrics
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• v.53 no.2
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• pp.248-252
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• 2010

Anomalous origins of coronary arteries are a rare type of disease among children. These anomalies can be categorized into 3 types according to the anatomical relationship of the aorta and pulmonary trunks. Among these types, the interarterial type, as observed in our case, needs early diagnosis and treatment, because it can increase the risk for the patient, causing sudden cardiac death in young individuals. Although there are controversies concerning the management of anomalous origins of the left coronary artery (LCA) in children, the result can be very beneficial, if treated accurately. Three well-known methods for correction of anomalous origins of LCA are re-implantation, coronary arterial bypass grafting (CABG), and unroofing. We report on the case of a 12-year-old girl who had chest discomfort and syncope with physical exercise and was later diagnosed with an anomalous origin of LCA by transthoracic echocardiography (TTE) and heart computed tomography (CT). She underwent a corrective operation by re-implantation, CABG, and unroofing.

• Journal of Chest Surgery
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• v.39 no.10 s.267
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• pp.749-753
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• 2006

Background: The purpose of this study is to assess a score system for operative risk evaluation of CABG. Material and Method: From January 2001 to September 2005, retrospective study for various perioperative factors of 2993 cases was done. Result: The early operative mortality was 2.4% and the beta coefficients of 7 core variables related to it (preoperative LV dysfuction, preoperative renal failure, MI within 1 week, reoperation, combined surgery, preoperative atrial fibrillation, preoperative IABP) were adjusted to score system. ROC curve and Hosmer and Lemeshow goodness of fit test was done. Conclusion: This score system was effective in assessing operative risk of CABG. But It is necessary to gather larger volume of case and perform multicenter study.

• Journal of Chest Surgery
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• v.53 no.1
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• pp.8-15
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• 2020

Background: We aimed to investigate the associations of critical care provided in a cardiac surgical intensive care unit (CSICU) staffed by an attending intensivist with improvements in intensive care unit (ICU) quality and reductions in postoperative complications. Methods: Patients who underwent elective isolated coronary artery bypass grafting (CABG) between January 2007 and December 2012 (the control group) were propensity-matched (1:1) to CABG patients between January 2013 and June 2018 (the intensivist group). Results: Using propensity score matching, 302 patients were extracted from each group. The proportion of patients with at least 1 postoperative complication was significantly lower in the intensivist group than in the control group (17.2% vs. 28.5%, p=0.001). In the intensivist group, the duration of mechanical ventilation (6.4±13.7 hours vs. 13.7±49.3 hours, p=0.013) and length of ICU stay (28.7±33.9 hours vs. 41.7±90.4 hours, p=0.018) were significantly shorter than in the control group. The proportions of patients with prolonged mechanical ventilation (2.3% vs. 7.6%, p=0.006), delirium (1.3% vs. 6.3%, p=0.003) and acute kidney injury (1.3% vs. 5.3%, p=0.012) were significantly lower in the intensivist group than in the control group. Conclusion: A transition from an open ICU model with trainee coverage to a closed ICU model with attending intensivist coverage can be expected to yield improvements in CSICU quality and reductions in postoperative complications.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.36-42
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• 1997

Though myocardial perfusion was usually expected to improve after coronary artery bypass graft(CABG) surgery, some myocardial segments were aggravated after operation, as we compared perfusion changes on postoperative SPECT with preoperative ones. In this study, we evaluated perfusion changes after operation in rest and stress myocardial SPECT in 44 patients (M:F=25:19, age 57.1 $year{\pm}8.2$) who had CABG before and 3 months after operation. We tried to find out possible causes for perfusion aggravation with multivariate logistic regression analysis regarding whether bypass graft was artery or vein and which coronary artery territory was operated. Among 616 myocardial segments which were operated, 89(14.4%) aggravated after operation. In the univariate analysis, myocardial segments in the left circumflex arteries(LCx) aggravated more often(p<0.01) than others and segments having operative angioplasty did less often(p<0.01). Multivariate logistic regression revealed that LCx was risk factor for perfusion aggravation [odds ratio=2.54 (95% confidence interval : 1.53-4.22, p<0.01)]. However, this was not the case when we analysed in terms of arterial territories. Among 106 coronary arterial territories which were operated, 27(25.5%) aggravated. The territories having aggravated had similar characteristics regarding whether they received arterial or venous grafts, angioplasty and whether the operated territories were left anterior descending, right coronary or left circumflex arteries. In conclusion, myocardial segments in the left circumflex artery tended to aggravate more often after bypass surgery than the others. In short-term comparison of perfusion after surgery, we could not find any tendency that arterial or venous graft was associated with more frequency of the aggravation of perfusion after operation.

• Journal of Chest Surgery
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• v.33 no.8
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• pp.638-642
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• 2000

Background: In an effort t enhance long term patency of coronary bypass grafts, utilization of arterial conduits have been on an icrease. With the same objective, we have been using the right gastroepiploic artery(RGEA)in coronary artery bypass procedures since 1998. The current paper has been undertaken with the aim of assessing the apropriateness, problems, and short term results of using the RGEA as an arterial graft conduit by studying the postoperative clinical results of 100 patients than received coronary artery bypass grafting (CARG) with this artery. Material and Method: Between May of 1998 and May of 1999, an analysis of the mortality, postoperative myocardial infarction, and the need for IABP insertion as a result of low cardiac output were made between 100 consecutive patients undergoing CABG with the RGEA. Result: There was one postoperative death due to cerebral infarction. Postoperative complications/morbidity comprised myocardial infarction in 2, cerebral infarct in 3, reoperation due to bleeding in 1, mediastinitis in 1, and low cardiac output syndrome necessitating IABP in 3 patients. Complicatons related to harvesting of the arterial grafts were not experienced in any of the patients. Conclusion: The results of the current data show that utilization of the RGEA in CABG is not associated with increased mortality/morbidity and demonstrates satisfactory short term results suggesting the usefulnessof this conduit as an arterial graft.

• Health Policy and Management
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• v.17 no.3
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• pp.87-105
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• 2007

The purpose of this study was to analyze whether nonemergency, isolated coronary artery bypass graft (CABG) surgery for high- or low-risk patients biases the assessment of the risk-adjusted mortality rates of hospitals. This study used 2002 National Health Insurance claims data for tertiary hospitals in Korea. The study sample consisted of 1,959 patients from 23 tertiary hospitals. The risk-adjustment model used the patients' biological, admission, and comorbidity data identified in the claims. The subjects were classified into high- and low-risk groups based on predicted surgical risk. The crude mortality rates and risk-adjusted mortality rates for low-risk, high-risk, and all patients in a hospital were compared based on the rank and the four intervals defined by quartile. Also, the crude mortality rates of the three groups were compared with their 95% confidence intervals of predicted mortality rates. The C-statistic (0.83) and Hosmer-Lemeshow test ($X^2$=11.47, p=0.18) indicated that the risk-adjustment model performed well. Presenting crude mortality rates with their 95% confidence intervals of predicted rates showed higher agreements among the three groups than using the rank or intervals of mortality rates defined by quartile in the hospital performance assessment. The crude mortality rates for the low-risk patients in 21 of the 23 hospitals were located on the same side of their 95% confidence intervals compared to that for all patients. High-risk patients and all patients differed at only one hospital. In conclusion, the impact of risk selection by hospital on the assessment results was the smallest when comparing the crude inpatient mortality rates of CABG patients with the 95% confidence intervals of predicted mortality rates. Given the increasing importance of quality improvements in Korean health policy, it will be necessary to use the appropriate method of releasing the hospital performance data to the public to minimize any unwanted impact such as risk-based hospital selection.

• Journal of Chest Surgery
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• v.26 no.4
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• pp.276-281
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• 1993

During the 3 years through December 1992, 118 cases of coronary bypass graft were performed at Department of Cardiothoracic Surgery, Asan Medical Center. They consisted of 80 males and 38 females with the mean age of 59. History of myocardial infarction was noted in 23 cases[20%], congestive heart failure in 11[10%], left ventricular aneurysm in 6, postinfarct VSD in 2, and mitral regurgitation in 1. The angina was stable in 13 cases, and unstable in 104 cases[89%]. Left main stem disease were 41 cases[35%], triple vessel 36[31%], double vessel 30[26%] and single vessel involvement[LAD] in 10. We performed 335 distal bypasses out of 117 cases, with single bypass in 9, double 29, triple 52, quadruple 23, and quintuple 4. Myocardial protections were cardioplegia in 29 and intermittent aortic occlusion 79 and continuous aortic perfusion 7. The ischemic time per graft was 13 minutes[intermittent aortic occlusion group] and 20 minutes [cardioplegia group] respectively, and the mean number of graft per patient is 2.85. Early mortality was 6.8% [8/117]. If we exclude the patients with LV aneurysm, the surgical mortality could be downed to 4.5% [5/111]. The causes of deaths were cardiogenic shock[6], aortic dissection[1], and neurologic complication[1]. We conclude that noncardioplegic myocardial protection may be equally beneficial or sometimes advantageous to cardioplegic technique in aortocoronary bypass graft surgery.

• Journal of Chest Surgery
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• v.42 no.2
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• pp.256-258
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• 2009

A 63-year-old man who had a permanent pacemaker placed 17 years ago presented to us with local inflammatory signs on his chest. The skin was opened to remove the permanent pacemaker. However, the pacing wire was not easily removed. So, the permanent pacemaker was removed from the chest with leaving the remnant wire inside. However, the local infection recurred because of the remnant wire. Right thoracotomy was performed and cardiopulmonary bypass was started. After total circulatory arrest, the right atrium was opened and the wire was completely removed.

• International Journal of Vascular Biomedical Engineering
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• v.3 no.1
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• pp.1-5
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• 2005

Background: Coronary atherosclerosis artery disease is the leading cause of morbidity and mortality. Coronary artery bypass grafting (CABG) which utilizes the saphenous vein graft, has helped in alleviating the suffering of these patients. Newer techniques are being developed to improve upon the techniques. Still there is significant number of failures, leading to re-grafting or re-vascularization. Some studies have helped in identifying the high and low shear stress regions. Further studies based on their realistic models are required. Material, methods and results: we developed the realistic model of fully blocked right coronary with bypass graft placed at angle of $5^0$ with curvature similar to that of artery. Pulsatile flow of birefringent solution through this model by polarized light was visualized. The images of complete flow field in the model were recorded and analyzed. Regions of high flow disturbances which are prone to further changes are identified. Existence of recirculation in the blocked coronary may initiate new blood-tissue interactions deleterious to bypass graft. Conclusion: Our study shows that by selecting the procedure to place bypass graft at minimum angle with curvature similar to that of artery and smooth sutures may improve the life span of the graft. This study also identified that coronary blocked regions contributing by recirculation flow at the proximal and distal regions of bypass which may require further studies.