• Journal of Chest Surgery
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• v.40 no.1 s.270
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• pp.56-59
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• 2007

A 65 year-old male had chest pain which was diagnosed as unstable angina needing urgent coronary artery bypass surgery. Physical examination demonstrated signs of severe anemia and hemoglobin level was 5.7 g/dL. Gastrofiberscopy showed a 4 cm sized fungating mass at the lesser curvature with active bleeding. The mass was adenocarcinoma by pathologic examination. Simultaneous coronary artery bypass surgery and total gastrectomy were planned due to bleeding of the mass. Off-pump coronary bypass grafting was done first, followed by total gastrectomy. The postoperative course was smooth. He was discharged from the hospital after 12 days and was on surveillance for 9 months. We report a rare case of simultaneous surgery for angina and gastric cancer.

• Journal of Chest Surgery
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• v.45 no.5
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• pp.301-307
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• 2012

Background: Perioperative transfusion of red blood cell (RBC) may cause adverse effects. Bloodless-cardiac surgery has been spotlighted to avoid those problems. Off pump coronary artery bypass (OPCAB) surgery can decrease the transfusion. However, the risk factors of transfusions in OPCAB have not been investigated properly. Materials and Methods: One hundred and thirteen patients (male:female=35:78, mean age=$66.7{\pm}9.9$ years) who received isolated OPCAB were retrospectively analyzed from March 2006 to September 2007. The threshold of RBC transfusion was 28.0% of hematocrit. Bilateral internal thoracic arteries graft were used for 99 patients (87.6%). One hundred and three (91.1%) and 35 patients (31.5%) took aspirin and clopidogrel just before surgery. Results: Sixty-five patients (47.5%) received the RBC transfusion (mean $2.2{\pm}3.2$ units). Mortality and major complications were not different between transfusion and no-transfusion group. But, ventilator support time, intensive care unit stay and hospitalization period had been reduced in no-transfusion group (p<0.05). In multivariate analysis, patients risk factors for RBC transfusion were preoperative low hematocrit (<37.5%) and clopidogrel medication. Surgical risk factors were longer graft harvesting time (<75 minutes) and total operation time (<5.5 hours, p <0.05). Conclusion: We performed the transfusion according to transfusion guideline; over 40% cases could conduct the OPCAB without transfusion. There were no differences in major clinical results between transfusion and non-transfusion group. In addition, when used together with accurate understanding of transfusion risk factors, it is expected to increase the proportion of patients that do not undergo transfusions.

• Journal of Chest Surgery
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• v.57 no.4
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• pp.399-407
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• 2024

Background: Pump-controlled retrograde trial off (PCRTO) is a safe, simple, and reversible method for weaning patients from veno-arterial extracorporeal membrane oxygenation (VA-ECMO). However, few studies have compared PCRTO to conventional weaning methods. This retrospective study aimed to compare PCRTO to non-PCRTO methods. Methods: This study included patients who were weaned from VA-ECMO from January 2016 to December 2022 at our medical center. Demographic data, ECMO management, ECMO complications, survival to discharge, and cardiogenic shock after VA-ECMO weaning were compared between the 2 groups. Results: Seventy patients who were weaned from VA-ECMO using PCRTO and 85 patients who were weaned with conventional methods were compared. Patient characteristics were not significantly different between the 2 groups. The rate of survival to discharge was significantly higher in the PCRTO group than in the non-PCRTO group (90% vs. 72%, p=0.01). The rates of freedom from all-cause mortality at 10, 30, and 50 days after weaning from ECMO were 75%, 55%, and 35% in the non-PCRTO group and 62%, 60%, and 58% in the PCRTO group, respectively (p=0.1). The incidence of cardiogenic shock after weaning from VA-ECMO was significantly higher in the non-PCRTO group (16% vs. 5%, p=0.04). In logistic regression analysis, PCRTO was a significant factor for survival to discharge (odds ratio, 2.42; 95% confidence interval, 1.29-5.28; p=0.02). Conclusion: Compared to conventional methods, PCRTO is a feasible and reversible method, and it serves as a useful predictor of successful VA-ECMO weaning through a preload stress test.

• Journal of Chest Surgery
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• v.43 no.3
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• pp.246-253
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• 2010

Background: Our objective was to review the long-term prognosis of patients with preoperative mild to moderate ischemic mitral regurgitation who underwent off-pump coronary artery bypass grafting. Material and Method: We prospectively followed 1,000 consecutive and systematic off-pump coronary artery bypass grafting patients who were operated on between September 1996 and March 2004; follow-up was achieved for 97%. Sixty-seven patients (6.7%) had mild to moderate ischemic mitral regurgitation at the time of surgery. Operative mortality, actuarial survival and major adverse cardiac event free survival were compared to assess the effect of ischemic mitral regurgitation. Result: Average follow-up was $66{\pm}22$ months. Patients with ischemic mitral regurgitation were older (p<0.001), had lower ejection fractions (p<0.001) and more comorbidities. Significantly more female patients presented with ischemic mitral regurgitation (p=0.002). There was no significant difference in operative mortality and perioperative myocardial infarction in ischemic mitral regurgitation patients (p=0.25). Eight-year survival was decreased in ischemic mitral regurgitation patients ($39.6{\pm}11.8%$ vs $76.7{\pm}2.2$, p<0.001). However, after correcting for risk factors, mild to moderate ischemic mitral regurgitation was not found to be a significant independent risk factor for long-term mortality (p=0.42). Major adverse cardiac event free survival at 8 years was significantly lower in ischemic mitral regurgitation patients ($53.12{\pm}12%$ vs $77{\pm}2%$, p<0.001). After correction for risk factors, ischemic mitral regurgitation remained a significant independent cause of major adverse cardiac events (HR: 2.31), especially congestive heart failure and recurrent myocardial infarction. Conclusion: In our series, patients with preoperative mild to moderate ischemic mitral regurgitation had a higher prevalence of preoperative risk factors than patients without ischemic mitral regurgitation. They had comparable perioperative mortality and morbidity, but, in the long term, were found to be at elevated risk for recurrent cardiac events.

• Journal of Chest Surgery
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• v.38 no.7 s.252
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• pp.476-482
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• 2005

Recently, coronary artery obstructive disease and coronary artery bypass graft surgery have increased, and the operative result has been improved. We reviewed 154 cases of coronary artery bypass graft surgery from Jan. 1985 to Jun. 2004. Material and Method: We reviewed 148 patients, 154 cases of coronary artery bypass surgery from Jan. 1985 to Jun. 2004. This investigation is designed to illustrate the preoperative diagnosis, severity of disease, operative method, the kind of used bypass graft used, number of distal anasomosis, associated surgery, and postoperative morbidity and mortality. Result: There were 84 males, 64 females and the average age was $58.9\pm8.3$ years old. Preoperative clinical diagnosis were unstable angina in 97 cases $(63.0\%)$, stable angina in 31 cases $(20.1\%)$, acute myocardial infarction in 12 cases $(7.8\%)$ and postinfartion angina in 14 cases $(9.1\%)$. Preoperative angiographic diagnosis were three-vessel disease in 68 $(44.2\%)$, two-vessel disease in 39 $(25.3\%)$, one-vessel disease in 35$(22.7\%)$, and left main disease in 12$(7.8\%)$ cases. There were 78 cases of on-pump coronary artery bypass graft surgery and 76 cases of off-pump coronary artery bypass graft surgery. The total distal anastomoses number was 319, mean number of anastomoses was $2.06\pm0.96$. There were 10 concomitant procedures. Postoperative intra-aortic balloon pump was used in 21$(13.6\%)$ cases, but only 4 cases were used at off-pump coronary artery bypass surgery. Total early mortality was $7.8\%$. The mortality was decreased as $4.5\%$ from Jan. 2001 to Jun. 2004. Post operative complication was perioperative yocardial infarction in 9cases$(5.8\%)$, low cardiac output syndrome in 17 cases$(11\%)$, and arrhythmia in 30 cases$(19.5\%)$ cases. Conclusion: Since 1985, The result of coronary artery bypass graft surgery has been improved because of more refined technique, use of off-pump coronary artery bypass surgery, use of internal thoracic artery and radial artery as bypass graft. We should study the long-term follow up more for better operative results.

• Journal of Chest Surgery
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• v.38 no.2 s.247
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• pp.116-122
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• 2005

Background: Adverse effects of cardiopulmonary bypass can be avoided by 'Off-pump' coronary artery bypass (OPCAB) surgery. Recent studies have reported that OPCAB had the most beneficial impact on patients at highest risk by reducing bypass-related complications. The purpose of this study is to compare the outcome of OPCAB and conventional coronary artery bypass grafting (CCAB) in patients with poor left ventricular (LV) function. Material and Method: From March 1997 to February 2004, seventy five patients with left ventricular ejection fraction (LVEF) of $35\%$ or less underwent isolated coronary artery bypass grafting at our institute. Of these patients, 33 patients underwent OPCAB and 42 underwent CCAB. Preoperative risk factors, operative and postoperative outcomes, including LV functional change, were compared and analysed. Result: Patients undergoing CCAB were more likely to have unstable angina, three vessel disease and acute myocardial infarction among the preoperative factors. OPCAB group had significantly lower mean operation time, less numbers of total distal anastomoses per patient and less numbers of distal anastomoses per patient in the circumflex territory than the CCAB group. There was no difference between the groups in regard to in-hospital mortality $(OPCAB\; 9.1\%\;(n=3)\;Vs.\;CCAB\;9.5\%\;(n=4)),$ intubation time, the length of stay in intensive care unit and in hospital postoperatively. Postoperative complication occurred more in CCAB group but did not show statistical difference. On follow-up echocardiography, OPCAB group showed $9.1\%$ improvement in mean LVEF, 4.3 mm decrease in mean left ventricular end-diastolic dimension (LVEDD) and 4.2 mm decrease in mean left ventricular end-systolic dimension (LVESD). CCAB group showed $11.0\%$ improvement in mean LVEF, 5.1 mm decrease in mean LVEDD and 5.5 mm decrease in mean LVESD. But there was no statistically significant difference between the two groups. Conclusion: This study showed that LV function improves postoperatively in patients with severe ischemic LV dysfunction, but failed to show any difference in the degree of improvement between OPCAB and CCAB. In terms of operative mortality rate and LV functional recovery, the results of OPCAB were as good as those of CCAB in patients with poor LV function. But, OPCAB procedure was advantageous in shortening of operative time and in decrease of complications. We recommend OPCAB as the first surgical option for patients with severe LV dysfunction.

• Tribology and Lubricants
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• v.28 no.4
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• pp.178-183
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• 2012

The fuel system of a vehicle is a very important compotent, as it provides the firing resources to the combustion chamber of the engine. However, improper operation of the system can generate bad condition or start-off during engine revolution. This study analyzed several examples of failure that had originated in the field. In the first example, the driver operated a vehicle containing both gasoline and LPG in the fuel tank, but the gasoline fuel remained unused for a few months. Therefore the fuel pump was clogged because of gasoline congelation. The second example, dealt with fuel leakage that occurred from the slightly torn O-ring connecting the fuel lines. The third example, pertained to engine damage and power-down owing to the usage of proor-quality fuel and ingredient. Therefore, it is necessary to take adequate measures to prevent the failure of the fuel system of vehicle.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.85-91
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• 1998

This paper describes an study electric injection system for diesel engines. It is needed effective fuel injection which controls the solenoid valve of fuel pump. To solve this, this paper proposes DCC-PWM method which can realize fast reply and low holding current for solenoid valve on/off. For the proposed design method, simulation tools of ACSL are used to analyze the system. And the single-chip microcomputer is used to reduce the size of controller and to improve flexibility. And the systems validity can be verified through the experimental results.

• Journal of the Korean Institute of Gas
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• v.19 no.3
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• pp.32-37
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• 2015

The boil-off-gases(BOG) in cryogenic LNG storage tanks are generating continuously due to the heat leakage and need to be re-liquefied by the effective way. As the present method to reliquefy BOG is using LNG cold energy to be supplied after low pressure primary pump, the demand of LNG flow rate should be over 10 times of BOG produced rate to reliquefy it. This research invented new effective re-liquefaction system having only 3~4 times of LNG flow rate against unit BOG, that the pre-liquefaction process of NGL and the use of high pressure LNG cold energy after secondary pump. By the analysis, it could be high efficient reliquefying system for all amount of BOG treatment even during the summer time, and improvement of operation safety and efficiency of LNG terminal.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.460-467
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• 2011

Cavitation phenomena during the spill process of the Bosch type fuel injection pump for medium-speed diesel engine were investigated by optical observations. Typically, these phenomena can cause a surface damage with material removal or round-off at the plunger and barrel port etc., and may shorten their expected life time. The images, which were recorded with high speed CCD camera and borescope, show that the plunger damage is mainly affected by fountain-like cavitation generated before the end of delivery. And the damages of barrel port and deflector are caused by jet-type cavitation generated after end of delivery.