• Nuclear Medicine and Molecular Imaging
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• v.40 no.6
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• pp.293-301
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• 2006

Purpose: The aim of the study was to evaluate the hemodynamic changes after successful bypass surgery in patients with atherosclerotic stenosis in ICA using $^{99m}Tc-ECD$ SPECT. Materials and Methods: Fourteen patients (M:F=8:6, mean age; $60{\pm}9$ years) who underwent STA-MCA anastomosis for unilateral atherosclerotic cerebrovascular disease were enrolled. $^{99m}Tc-ECD$ basal/acetazolamide perfusion SPECT studies were performed before, 10 days and 6 months after bypass surgery. Perfusion reserve was defined as the % changes after acetazolamide over rest image. Regional cerebral blood flow and perfusion reserve were compared preoperative, early-postoperative and late-postoperative scans. Results: The mean resting perfusion and decrease in perfusion reserve in affected ICA territory on preoperative scan was $52.4{\pm}3.5\;and\;-7.9{\pm}4.7%$, respectively. The resting perfusion was significantly improved after surgery on early-postoperative scan (mean $53.7{\pm}2.7$) and late-postoperative scan (mean $53.3{\pm}2.5$) compared with preoperative images (p<0.05, respectively). Resting perfusion did not showed further improvement on late-postoperative scan compared with early-postoperative scan. The perfusion reserve was $-3.7{\pm}2.6%$ on early-postoperative scan, and $-1.6{\pm}2.3%$ on late-postoperative scan, which was significantly improved after surgery. Additionally, further improvement of perfusion reserved as observed on late-postoperative scan (p<0.05). While, in the unaffected ICA territory, no significant changes in the resting perfusion and perfusion reserve was observed. Conclusion: The improvement of resting perfusion and perfusion reserve in early-postoperative scan reflects the immediate restoration of the cerebral blood flow by bypass surgery. In contrasts, further improvement of perfusion reserve showing on late-postoperative scan may indicate a good collateral development after surgery, which may indicate good surgical outcome after surgery.

• Journal of Chest Surgery
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• v.35 no.4
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• pp.283-289
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• 2002

Backgrouds: It is almost universally accepted that occlusive vascular diseases are best managed by anatomical reconstruction. However, the mortality and the morbidity have limited this operation for patients with high operation risks. In these patients, palliative operations such as extra-anatomic bypass and lumbar sympathectomy, are accepted as useful treatment. Material and Method: A retrospective study was conducted in 38 patients who underwent palliative operations for occlusive vascular disease at Korea University Guro Hospital between 1996 and 2000. Mean age of the patients was 60.37 $\pm$ 17.65 years, and preoperative diagnoses were atherosclerosis in 32 patients, Buerger's disease in 4 patients, Raynaud's syndrome in 1 patient and SVC syndrome in 1 patient. Result: Extra-anatomic bypass(40procedures), lumbar sympathectomy(17), thromboembolectomy(7) and femoral artery graft interposition(1) were performed. Six patients were required reoperation due to graft flow failure or fistula. Three year primary patency rate of entire operations was 78.29 $\pm$ 8.81%, and the correlation between type of operation and patency rate was not statistically significant. Conclusion: Palliative operations for occlusive vascular disease are useful treatment in limited patients with high operation risks or limited life expectancy.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.235-244
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• 2020

This study conducted a series of studies to offer a novel method of using CBS-dust that produced as by-product in the manufacture of cement. Four different contents of BS and CBS-dust were adopted for test parameters of this study. Mortar with 50% of W/B was fabricated. First, in the case of the fresh mortar, the flow decreased as the CBS-dust replacement rate increased, but the binder composition ratio BS 45% and 65% showed higher fl ow than Pl ain when repl acing CBS-dust 5%. In the case of air content, overall, the tendency was proportional to the CBS-dust replacement rate, and chloride tended to exceed the reference value at all replacement rates except for the CBS-dust 0% replacement. The compressive strength of the hardened mortar shows the resul t that the strength is improved when the CBS-dust is repl aced by 5% to 10%, and the CSH gel and structure formation is confirmed by microstructure analysis through the hydration reaction when the CBS-dust is replaced. Therefore, for a given condition CBS-dust is used as a early-strength admixture in a concrete secondary product that uses a large amount of admixture without reinforcing bars it can be an effective method for enhancing the strength of concrete as an alkali activator.

• Journal of Chest Surgery
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• v.44 no.1
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• pp.9-17
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• 2011

Background: A peripheral extracorporeal membrane oxygenator (p-ECMO) has been developed to support patients who are dying due to a serious cardiopulmonary condition. This analysis was planned to define the clinical situation in which the patient benefits most from a p-ECMO. Material and Methods: Between June 2007 and Aug 2009, a total of 41 adult patients used the p-ECMO. There were 23 males and 18 females (mean age $54.4{\pm}15.1$ years). All patients had very unstable vital signs with hypoxia and complex cardiac problems. We divided the patients into 4 groups. In the first group, a p-ECMO was used as a bridge to cardiac operation. In the second group, patients did not have the opportunity to undergo any cardiac procedures; nevertheless, they were treated with a p-ECMO. In the third group, patients mostly had difficulty in weaning from CPB (cardiopulmonary bypass) after cardiac operation. The fourth group suffered from many complications, such as pneumonia, bleeding, infections, and LV dysfunction with underlying cardiac problems. All cannulations were performed by the Seldinger technique or cutting down the femoral vessel. A long venous cannula of $DLP^{(R)}$ (Medtronic Inc, Minneapolis, MN) or $RMI^{(R)}$ (Edwards Lifesciences LLC, Irvine, CA) was used together with a 17~21 Fr arterial cannula and a 21 Fr venous cannula. As a bypass pump, a Capiox emergency bypass system ($EBS^{(R)}$; Terumo, Tokyo, Japan) was used. We attempted to maintain a flow rate of $2.4{\sim}3.0\;L/min/m^2$ and an activated clotting time (ACT) of around 180 seconds. Results: Nine patients survived by the use of the p-ECMO. Ten patients were weaned from a p-ECMO but they did not survive, and the remainder had no chance to be weaned from the p-ECMO. The best clinical situation to apply the p-ECMO was to use it as a bridge to cardiac operation and for weaning from CPB after cardiac operation. Conclusion: Various clinical results were derived by p-ECMO according to the clinical situation. For the best results, early adoption of the p-ECMO for anatomical correction appears important.

• Journal of Chest Surgery
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• v.38 no.10 s.255
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• pp.661-668
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• 2005

Background: We have hypothesized that, if a low resistant gravity-flow membrane oxygenator is used, then the twin blood sacs of TPLS can be located at downstream of the membrane oxyenator, which may double the pulse rate at a given pump rate and increase the pump output. The purpose of this study was to determine the optimal configuration for the ECLS circuits by using the concept of pulse energy and pump output. Material and Method: Animals were randomly assigned to 2 groups in a total cardiopulmonary bypass model. In the serial group, a conventional membrane oxygenator was located between the twin blood sacs. In the parallel group, the twin blood sacs were placed downstream of the gravity-flow membrane oxygenator. Energy equivalent pressure (EEP) and pump output were collected at pump-setting rates of 30, 40, and 50 BPM. Result: At the given pump-setting rate, the pulse rate was doubled in the parallel group. Percent changes of mean arterial pressure to EEP were $13.0\pm1.7,\; 12.0\pm1.9\;and\;7.6\pm0.9\%$ in the parallel group, and $22.5\pm2.4,\; 23.2\pm1.9,\;and\;21.8\pm1.4\%$ in the serial group at 30, 40, and 50 BPM of pump-setting rates. Pump output was higher in the parallel circuit at 40 and 50 BPM of pump-setting rates $(3.1\pm0.2,\;3.7\pm0.2L/min\;vs.\;2.2\pm0.1\;and\;2.5\pm0.1L/min,\;respectively,\;p=0.01)$. Conclusion: Either parallel or serial circuit configuration of the ECLS generates effective pulsatility. As for the pump out, the parallel circuit configuration provides higher flow than the serial circuit configuration.

• Journal of Chest Surgery
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• v.9 no.1
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• pp.1-9
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• 1976

The present. study reports four cases of congenital heart diseases, who received open heart surgery by the Sarn's Heart-Lung-Machine in the department of Thoracic Surgery, Hanyang University Hospital during the period between July 1975 and May 1976. The Heart-Lung-Machine consisted of the Sarn's five head roller pump motor system (model 5000), heat exchanger, bubble trap, the Rygg-Kyvsgaard oxygenator, and monitors. The priming of pump oxygenator was carried out by the hemodilution method using Hartman's solution and whole blood. Of the four cases of the heart diseases, three whose body weight were below 30kg, received the partial hemodilution priming and the remaining one whose body weight was 52kg received the total hemodilution priming with Hartman's solution alone. The rate of hemodilution was in the average of 60.5ml/kg. Extracorporeal circulation was performed at the perfusion flow rate of the average 94.0ml/kg/min, and at the moderate hypothermia between 35'5"C and 30'5"C of the rectal temperature. In the total cardiopulmonary bypass, arterial blood pressure was anged between 30 mmHg and 85 mmHg, generally maintaining over 60 mmHg and venous pressure was measured between 4 and $23cmH_2O$, generally maintaining below $10cmH_2O$. The first case: The patient, a nine year old girl having the symptoms and physical signs typical to cardiac anomaly was definitely diagnosed as isolated pulmonary stenosis through the cardiac catheterization. There was, however, no cyanosis, no pathological finding by X-ray and E.C.G. tracings. The valvulotomy was performed through the arteriotomy of pulmouary artery under the total cardiopulmonary bypass. Postoperative course of the patient was uneventful, and murmur and the clinical symptoms disappeared. The second case: A 12 year old boy with congenital heart anomaly was positively identified as having ventricular septal defect through the cardiac catheterization. As in the case with the first case, the patient exhibited the symptoms and physical signs typical to cardiac anomaly, but no pathological abnormality by X-ray and E.C.G. tracings. The septal defect was localized on atrioventricular canal and was 2 by 10 mm in size. The septal defect was closed by direct simple sutures under the cardiopulmonary bypass. Postoperative hemodynamic study revealed that the pressure of the right ventricle and pulmonary artery were decreased satisfactory. Postoperative course of the patient was uneventful, and murmur and the clinical symptoms disappeared. The third case: The patient, a 19 year old girl had been experienced the clinical symptoms typical to cardiac anomaly for 16 years. The pink tetralogy of Fallot was definitey diagnosed through the cardiac catheterization. The patient was placed on an ablolute bed rest prior to the operation because of severe exertional dyspnea, fatigability, and frequent syncopal attacks. However, she exhibited very slight cyanosis. Positive findings were noted on E.C.G. tracings and blood picture, but no evidence of pathological abnormality on X-ray was observed. All of the four surgical approaches such as Teflon patch closure (3 by 4cm in size) of ventricular septal defect, myocardial resection of right ventricular outflow tract, valvulotomy of pulmonary valvular stenosis, and pericardial patch closing of ventriculotomy wound were performed in 95 minutes under the cardiopulmonary bypass. Postoperative hemodynamic study revealed that the pressure of the right ventricle was decreased and pulmonary artery was increased satisfactorily. Postoperative course of the patient was uneventful, and murmur and the clinical symptoms disappeared. The fourth case: The patient, a 7 1/4 year old girl had the symptoms of cardiac anomaly for only three years prior to the operation. She was positively identified as having acyanotic tetralogy of Fallot by open heart surgery. The patient showed positive findings by X-ray and E.C.G. tracings, but exhibited no cyanosis and normal blood picture. All of the three surgical approaches, such a myocardial resection of hypertrophic sight ventricular outflow tract, direct suture closing of ventricular septal defect and pericardial patch closing of ventriculotomy wound were carried out in 110 minutes under the cardiopulmonary bypass. Postoperative hemodynamic study revealed that the pressure of the right ventricle was decreased and pulmonary artery was increased satisfactorily. Postoperative course of the patient was uneventful, and the symptoms disappeared.

• Journal of Chest Surgery
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• v.31 no.7
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• pp.674-678
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• 1998

The conventional surgical treatment of isolated critical stenosis of the left main coronary artery restores a less physiologic perfusion of the myocardium, leads to occlusion of the left coronary ostium, and consumes an appreciable length of bypass material. From June 1994 to February 1996, eleven patients, three male and eight female, underwent patch angioplasty and additional bypass graft to left anterior descending artery (10 internal mammary artery, 1 saphenous vein) in isolated critical left main coronary artery stenosis. Their ages ranged from 34 to 62 years, mean 44 years. All had 60% to 90% stenosis of the left main coronary artery and Class III angina. The angiogram showed nine osteal lesion and three main stem stenosis. The operation was performed with conventional cardiopulmonary bypass and cold blood cardioplegia. We approached anteriorly and used bovine pericardium as onlay patch in all patients. There were one leg wound dehiscence, but no operative deaths and infarctions. All patients are free of symptoms after a mean follow-up of 15.5 months. Angiographic restudy at an average 14.4 months was obtained in five patients and showed widely patent left main coronary artery with excellent runoff. But additional graft to left anterior descending coronary artery were stenosed in two patients and showed diminutive flow in others. Our preliminary results suggest that angioplasty of the left main coronary artery can be carried out with low operative risks. But additional bypass graft to left anterior descending coronary artery may be unnecessary. The technique appears to be a promising alternative to conventional coronary artery bypass grafting in isolated left main coronary artery stenosis.

• Journal of Chest Surgery
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• v.37 no.1
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• pp.35-42
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• 2004

Background: For the treatment of isolated left main coronary artery disease, twelve arterial revascularizations with Y-composite grafts using left internal thoracic artery and radial artery or right gastroepiploic artery were peformed. This study was performed to investigate whether V-composite graft can satisfy the blood flow required to make myocardium act properly or not. Borderline stenotic lesions on the left main coronary artery, which are very prone to remodel the bypassed vessels due to competitive flows, were also considered. Material and Method: Among 247 patients who underwent coronary artery bypass grafting from March 2000 to April 2003, 12 patients (4.7%) who had received total arterial revascularizations for the isolated left main coronary artery disease were studied retrospectively. Result: left anterior descending arteries were bypassed with left internal thoracic artery by off-pump technique in all patients, however, 2 cases of left obtuse marginal branches were bypassed under on-pump beating heart. Except for one patient, who did not have an obtuse marginal branch more than 1 mm in diameter, 11 patients had gone through complete arterial revascularizations by use of the Y shape arterial graft. Among five patients who had less than 75% stenosis, one patient showed string sign on left internal thoracic artery grafted to left anterior descending artery. However, two grafts to obtuse marginal blanches were completely obstructed and one showed slender sign. There were no graft-dominant flow in patients with stenotic lesion less than 75%. On the contrary to the result of patients with stenotic lesions less than 75%, all the patients with stenotic lesions more than 90% showed graft-dominant blood flow. Conclusion: In conclusion, it is assumed that, when stenotic lesions are over 90%, coronary artery bypass grafting with an Y shape arterial graft could possibly give enough help to the obstructed coronary arteries in blood supplying to myocardium, which needs massive quantity of blood to act well. However, when patients have borderline stenoses, through scrupulous examinations, more prudent and flexible decisions are required in choosing the treatment methods, such as, direct anastomosis of vein or artery to aorta, or adding supplementary treatment methods like percutaneous coronary intervention, rather than choosing a fixed treatment methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.14-21
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• 2017

The extreme floods recently are have been attributed global warming, The development of a canal tunnel to prevent floods by making a bypass or undercurrent to flood discharge in a major flooding area is required because urban flooding in heavy rainfall occurs frequently, increasing the impermeability according to lack of capacity in sewage to urbanization by the existing urban basin. In this study, a numerical simulation was performed to support design standards for a multi-purpose waterway tunnel combined road tunnel of canal tunnel. The numerical simulation showed that the size of the friction loss occurring in the tunnel section of the same channel occurred more than the theoretically calculated frictional loss derived from the numerical simulations. This is probably due to the additional frictional loss caused by the change in the flow structure due to the geometry of the pipe when the shape of the channel is non-circular. The increase in friction loss was more pronounced in the laminar flow than in the turbulent flow. Depending on the shape of the conduit, the friction loss should be adjusted for accurate flow calculations. This result can provide the basin information about the design of flood by a pass conduit.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.89-95
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• 2015

A surge phenomenon cause noise and pulsations in a turbo compressor, which is an unstable operating regime. Because surge protection ensures a safe compressor operation, it is important to understand the physics of the surge phenomenon. In this study, the surge characteristics of a 250-hp class turbo-compressor were evaluated experimentally. The experimental parameters were the rotational speed, opening angles of the inlet guide vane and exit valve, and inlet pipe diameter and flow rates of the inlet gases. The results showed that the compressor surge was very sensitive to the gas flow rates, exit pressure, rotational speed, and bypass flow rates.