• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.70-77
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• 2013

The present study has been carried out to analyze the effect of steam hammering on the steam piping system including the final superheater, the high pressure turbine, check valve and the first reheater by sudden stoping of main stop valve in a power plant. For the present steam hammering analysis, the well known Flowmaster software has been used to model the steam piping system and the time dependent characteristics of pressure and steam mass flow rate has been conducted. Using the result of the unsteady pressure and steam mass flow rate, the forces acting on the elbows in the piping system has been derived. From the present analysis, it has been elucidated that the elbow just before the main stop valve and the elbow near the connection pipe between bypass pipe and check valve had the largest force among the elbows in the steam piping system. The structural safety diagnostics study on the elbow and the supporting structures of the steam piping system of a power plant will be conducted in the future by the present results of the forces acting on the elbow.

• Journal of Chest Surgery
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• v.32 no.8
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• pp.709-714
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• 1999

Background: When internal thoracic artery (ITA) and saphenous vein graft are anastomosed to the same coronary artery, the patency rate of the internal thoracic artery graft with relatively narrow diameter may be decreased owing to competition of pressure and flow rate. We evaluate the clinical outcome and the patency of the ITA graft in patients undergoing dual grafting to the same coronary artery. Material and Method: In 14 patients with the ITA graft having relatively low flow, the ITA and saphenous vein graft were anastomosed to the same coronary artery. During the mean follow-up period of 33.5 months, coronary angiography was performed in 6 patients who complained of recurrent angina, needed confirmation of graft flow, or showed postoperative Q wave. Result: In all 6 patients, the ITA and saphenous vein grafts were patent without stenosis or obstruction. Two patients showed good flow in both grafts, 2 showed competitive flow in the ITA graft, and the remaining 2 showed poor flow in the ITA graft. Conclusion: Early operative closure When saphenous vein grafting was added to the same coronary artery that the internal thoracic artery was anastomosed to, the perfusion to the coronary artery was satisfied and the dual grafting did not affect the short-term and mid-term patency rate of the ITA.

• Journal of Chest Surgery
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• v.13 no.4
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• pp.321-337
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• 1980

The increasing use of cardioplegic solution for the reduction of ischemic tissue injury requires that all cardiplegic solution be carefully assessed for any protective or damaging properties. This study describes functional, enzymatic and structural assessment of the efficiency of three cardioplegic solutions (Young & GIK, Bretschneider, and $K^{+}$ Albumin solution) in a Modified Isolated Rat Heart Model of cardiopulmonary bypass and ischemic arrest. Isolated rat heart were subjected to a 2-minute period of coronary infusion with a cold cardioplegic or a noncardioplegic solution immediately before and also at the midpoint of a 60-minute period of hypothermic ($10{\pm}1$. C) ischemic cardiac arrest. The results of this study were as follow: 1. Spontaneous heart beat after ischemic arrest occured 16 seconds later after Langendorff reperfusion in the Young & GIK group (n=6), and 40 second later in the Bretschneider group (n=6) and 6 minute later in the $K^{+}$ Albumin group (n=6), and 16 minute later in the control group (non-cardioplegia). A good recovery state of spontaneous heart beat was shown in the Young & GIK and Bretschneider groups. 2. The percentage of recorveries of heart function at 30 minute after postischemic working heart perfusion were : heart rate $91.6{\pm}3.1$% (P<0.01)m oeaj airtuc oressyre $83{\pm}3$% (P<0.01), coronary flow $70{\pm}8$% (P<0.05) and aortic flow flow rate $39{\pm}9.3$% (P<0.05) in the Young & GIK group. This percentage of recoveries of the Young & GIK group was significantly greater than the control group. In the Bretschneider group, the percentage of recoveries were : heart rate $87.8{\pm}7.5$%(P<0.05), peak aortic pressure $71{\pm}2.3$% (P<0.05) and aortic flow rate $33.2{\pm}6.6$%(P<0.05). hte percentage of recoveries were significantly greater than in the control group. In the $K^{+}$ Albumin group, recoveries of heart function were poor. 3. Total CPK leakage was $131.2{\pm}12.75$IU/30 min/gm. dry weight in the control group, $50.65{\pm}12.75$IU in the Young & GIK gruop, $69.40{\pm}32.21$Iu in Bretschneider group, and $103.65{\pm}15.47$IU in the $K^{+}$ Albumin group during the 30 minute postischemic Langendorff reperfusion. Total CPK leakage was significantly less (P<0.001) in the Young & GIK group, than in the control group. 4. Direct correlatin between percentage recovery of aortic flow rate and total amount of CPK leakage from Myocardium was noticed.(Correlation Coefficient r = 0.76, P<0.001). 5. Mild perivascular edema was the only finding of light microscopic study of myocardium after 60 minute ischemic arrest with cold cardioplegic solutions and hypothermla.

• Journal of Chest Surgery
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• v.49 no.3
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• pp.145-150
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• 2016

Background: Extracorporeal circulation (ECC) can induce alterations in blood viscoelasticity and cause red blood cell (RBC) aggregation. In this study, the authors evaluated the effects of pump flow pulsatility on blood viscoelasticity and RBC aggregation. Methods: Mongrel dogs were randomly assigned to two groups: a nonpulsatile pump group (n=6) or a pulsatile pump group (n=6). After ECC was started at a pump flow rate of 80 mL/kg/min, cardiac fibrillation was induced. Blood sampling was performed before and at 1, 2, and 3 hours after ECC commencement. To eliminate bias induced by hematocrit and plasma, all blood samples were adjusted to a hematocrit of 45% using baseline plasma. Blood viscoelasticity, plasma viscosity, hematocrit, arterial blood gas analysis, central venous $O_2$ saturation, and lactate were measured. Results: The blood viscosity and aggregation index decreased abruptly 1 hour after ECC and then remained low during ECC in both groups, but blood elasticity did not change during ECC. Blood viscosity, blood elasticity, plasma viscosity, and the aggregation index were not significantly different in the groups at any time. Hematocrit decreased abruptly 1 hour after ECC in both groups due to dilution by the priming solution used. Conclusion: After ECC, blood viscoelasticity and RBC aggregation were not different in the pulsatile and nonpulsatile groups in the adult dog model. Furthermore, pulsatile flow did not have a more harmful effect on blood viscoelasticity or RBC aggregation than nonpulsatile flow.

• Journal of Internet Computing and Services
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• v.21 no.1
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• pp.179-190
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• 2020

In the Unix-like system environment, the GOT overwrite attack is one of the traditional control flow hijacking techniques for exploiting software privileges. Several techniques have been proposed to defend against the GOT overwrite attack, and among them, the Full Relro(Relocation Read only) technique, which blocks GOT overwrites at runtime by arranging the GOT section as read-only in the program startup, has been known as the most effective defense technique. However, it entails loading delay, which limits its application to a program sensitive to startup performance, and it is not currently applied to the library due to problems including a chain loading delay problem caused by nested library dependency. Also, many compilers, including LLVM, do not apply the Full Relro technique by default, so runtime programs are still vulnerable to GOT attacks. In this paper, we propose a GOT protection scheme using the Control Flow Integrity(CFI) technique, which is currently recognized as the most suitable technique for defense against code reuse attacks. We implemented this scheme based on LLVM and applied it to the binutils-gdb program group to evaluate security, performance and compatibility. The GOT protection scheme with CFI is difficult to bypass, fast, and compatible with existing library programs.

• Journal of Chest Surgery
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• v.38 no.11 s.256
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• pp.733-738
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• 2005

Background: The possibility of incomplete revascularization and development of flow competition after revascularization of the borderline lesion made the hybrid strategy as an option for complete revascularization. Material and Method: From January f998 to July 2004, 25 $(3.2\%)$ patients underwent hybrid revascularization among 782 total OPCAB procedures. Clinical results and angiographic patencies were evalulated. Percutaneous coronary intervention (PCI) was peformed before CABG in 8 patients and after CABG in 47 patients. Result: The causes of PCIs before CABG were to achieve complete revascularization with minimally invasive surgery (n=7) and emergent PCI for culprit lesion (n=1). The indications of PCIs after CABG were high possibility of flow competition in the borderline lesion of right coronary artery territory (n=8), diffuse atheromatous lesion preventing anastomosis of graft (n=5), severe calcified ascending aorta with no more arterial grafi available (n=3), and intramyocardial coronary lesion (n=1). Mean number of distal anastomoses was $2.3\pm1.0$. Mean number of lesions treated by PCI was $1.2\pm0.4$. There was no operative or procedure-related mortality. PCI-related complication was periprocedural myocardial infarction in one patient, and complications related to CABG were transient atrial fibrillation (n=5), perioperative myocardial infarction (n=1), and transient renal dysfunction (n=1). Early postoperative coronary angiography $(1.8{pm}1.6days)$ revealed $100\%$ patency rate of grafts (57/57). The stenosis occurred in one patient performed PCI before CABG, which was successfully treated with re-ballooning. During midterm follow-up (mean; $25{\pm}26$ months), 1 patient died of congestive heart failure. All survivors (n=24) accomplished follow-up coronary angiographics, which showed .all grafts (56/57) were patent except one string sign. In-stent restenosis was developed in 2 patients who received bare metal stents. Conclusion: In selected patients, complete revascularization was achieved with low risk by taking the hybrid strategy.

• Journal of Chest Surgery
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• v.30 no.6
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• pp.591-597
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• 1997

Cardiopulmonary bypass in children is associated with capillary leak which results in an increase in total body water after open heart surgery The purpose of these studies was to assess the cardiopulmonary effects of modified ultrafiltration after pediatric open heart surgery Study h: Twenty-six consecutive children aged 0.1 ~ 10 years(median 7 months) underwent cardiac operation inc rporating modified ultrafiltration. After completion of cardiopulmonary bypass, modified ultrafiltration was commenced at the flow rate of 100~ 15011min for 3 ~ 14 min. After modified ultrafiltration, elevation of hematocrit(28.3% $\pm$ 3.6% vs. 33.8olo $\pm$ 4.Ooloi p < 0.001), increased systolic 1)loots Pressure(66.7 $\pm$ 11.2mmHg vs. 76.2$\pm$ 11.BmmHg, p < 0.02), and decreased central venous pressure(7.8 $\pm$ 3.7mmHg vs. 6.9$\pm$ 2.gmmHg, p<0.001) were observed. Study B: Twenty-six children who underwent cardiac operation with the diagnosis of VSD under 2 years were assigned to control(n= 14) or modified ultrafiltration(n= 12). Peak inspiratory pressure checked immediately after operation was significantly lower in modified ultrafiltration group than in control group(20.0$\pm$ 2.4 cmH20 vs.22.4$\pm$ 2.3cmH20, p < 0.03). Modified ultrafiltration after cardiopillmonary bypass in children improves early homodynamics and pulmonary mechanics, and represents an excellent option for perioperative managemen of accumulation of fluid in the tissues. We will continually employ the modified ultrafiltration technique in pediatric cardiac operations.

• Journal of Chest Surgery
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• v.28 no.3
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• pp.268-273
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• 1995

Budd- chiari syndrome resulting from a membranous obstruction of the inferior vena cava[IVC is a rare congenital anomaly. From January 1989 to December 1993, 8 cases of IVC obstruction was treated in Kyung Hee Univ. Hospital. There were 2 male and 6 female patients between 34 and 66 years of age[mean 47.3$\pm$11.9 years of age . 4 patients were treated with angioplasty by balloon catheter and 4 patients were treated with operative correction using cardiopulmonary bypass, profound hypothermia and total circulatory arrest. These 4 patients were repaired the constricted IVC with autologous pericardial patch. In surgically treated patients, all of the specimens were confirmed to be membranous web histopathologically. Postoperative outcome in operative correcting patients was uneventful and postoperative angiography showed unobstructed flow through the IVC with filling of the hepatic veins.The above 8 patients were followed up from 10 months to 56 months [ mean 36.43 17.24 months and recurrent IVC obstruction or stenosis was not seen.

• Journal of Chest Surgery
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• v.25 no.4
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• pp.406-411
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• 1992

Thirty-four patients were received bidirectional cavopulmonary shunt[BCPS] from Aug. 1989 to Apr. 1991 at Sejong General Hospital, Puchon, Korea. Their ages were from 43 days to 21 years old with 19 cases of infant, 10 from 1 to 5 years old and 5 cases above 6 years old. Their diagnoses were as follows: 13 cases with uni-ventricular heart, 9 tricuspid atresia, 6 double outlet of right ventricle, 4 pulmonary atresia with intact ventricular septum, and 2 transposition of great arteries with pulmonary stenosis. Among them, 10 patients had received other palliative operations before. The BCPS operations were performed under the cardiopulmonary bypass and 10 patients who had bilateral superior vena cava received bilateral BCPS. Other associated procedures were 9 cases of takedown of Blalock-Taussig shunt, 3 pulmonary artery angioplasty, 1 unifocalization, 1 repair of total anomalous pulmonary venous return, 1 Damus procedure, 1 relief of sub-aortic stenosis, 1 right ventricular outflow tract reconstruction and one case of tricuspid valve obliteration. There were 3 operative deaths[8.8%] and two late deaths. The remainders show good postoperative state and their oxygen saturation was increased significantly. Conclusively, the bidirectional cavopulmonary shunt is very effective and safe palliative or pre-Fontan stage operation for the many complex congenital anomalies with low pulmonary blood flow especially for the patients who have the risk of Fontan repair.

• Journal of Chest Surgery
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• v.28 no.8
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• pp.759-765
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• 1995

We reviewed our experiences on 33 patients who underwent a bidirectional cavopulmonary shunt[BCPS from February 1992 to July 1994. There were 19 male an 14 female patients, and their weight ranged from 4.4 to 13.3 Kg[mean weight 8.4 $\pm$2.9 Kg . The age ranged from 2 to 55 months [mean age 16.7 $\pm$15.5 months . Their diagnosis included single ventricle group in 16, unbalanced ventricles in 8 whose associated anomalies were double outlet right ventricle, transposition of great arteries and total anomalous pulmonary venous return, tricuspid atresia in 7, hypoplastic left heart syndrome in 1 who underwent a Norwood procedure and double outlet right ventricle with pulmonic stenosis and tricuspid stenosis in 1 who underwent biventricular repair. Among them 10 patients had received other palliative operation before [Norwood procedure 1, pulmonary artery banding 3, modified Blalock-Taussig shunt 6 . The BCPS operations were performed under the cardiopulmonary bypass. 16 patients underwent unilateral BCPS and 17 patients who had bilateral SVC underwent bilateral BCPS. Three patients whose associated anomalies were interruption of IVC underwent total cavopulmonary shunt. There were 5 operative deaths [mortality rate 15.1 % and 2 late deaths. The risk factor for the operation was high mean pulmonary artery pressure [p value<0.05 . The survivors showed good postoperative course and their postoperative oxygen saturation was increased significantly compared to that of preoperative status[p value<0.05 .Conclusively, BCPS operation is effective and safe palliative procedure for the many cyanotic complex congenital anomalies with decreased pulmonary blood flow especialy for the patients who have the high risk factors for Fontan operations.