• Journal of Chest Surgery
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• v.38 no.10 s.255
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• pp.693-698
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• 2005

Background: Sinus valsalva aneurysm (SVA) is a rare disease, and it is frequently accompanied by ventricular septal defect and aortic valve regurgitaion. For treatment of SVA, several surgical mordalities were applied, but there was no report on the long-term result after surgical repair in Korea. We reviewed our 28 years of experiences and analyzed the long-term results after treatment of sinus valsalva aneurysm with or without rupture. Material and Method: Between March 1974 and February 2002, 81 patients were operated under the impression of sinus valvsalva aneurysm or sinus valsalva aneurym rupture. Retrospectively we reviewed the patients' record. Mean age of patients was $29.2\pm11.5$ and there were 49 males. Accompanyng diseases were as follows: VSD in 50, PDA in 2, Behcet's disease in 2, TOF in 1, RVOTO in 1, AAE in 1. Seventy-seven $(95\%)$ patients had sinus valsalva rupture and in 14 patients, subacute bacterial endocarditis was accompanied. Degree of aortic valve regurgitation was as follows: grade I: 8, II: 10, III: 9, IV: 4. Most common rupture site was right coronary sinus (66 patients, $81\%$) and most common communication site was right ventricle (53 patients). In repair of sinus valsalva rupture, patch was used in 37 patients, and direct suture was done in 38 patients. Result: There was one surgical death $(1.2\%)$. Follow up was done in 78 patients $(97.5\%)$, mean follow up period was $123.3\pm80.9(3\~330\;months)$. During the follow up period, 3 patients died $(3.8\%)$. One patient died of heart failure, another patient died of arrhythmia and the other one died of unknown cause. In two patients, complete atrio-ventricular block was developed during follow up period, and there was no operation related event or complication. Kaplan-Meier survival analysis revealed $92.5\pm3.5\%$ survival at 15 and 27 years and it seems to be satisfactory. Conclusion: Long-term surgical results and survival is satisfactory after repair of sinus valsalva aneurysm with or without rupture.

• Journal of Chest Surgery
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• v.36 no.12
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• pp.961-969
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• 2003

The purpose of this study was to evaluate the fate of left atrioventricular valve regurgitation(LAVVR) following repair of complete atrioventricular septal defects (AVSDs). Material and Method: Between July 1984 and March 2002, repair of complete AV defects were performed in 77 patients. Mean age at surgery was 30.23$\pm$69.11 months (range 1 to 456). Echocardiograms of all survivors after isolated AVSDs correction were reviewed. LAVVR were evaluated with color doppler echocardiography in 64 survival periodically. On each study, LAVVR severity was graded on a 1 to 4 scale, based upon the size of the regurgitated jet. Result: Mild deterioration of LAVV function was fairly common. LAVVR severity increased by >1 grade in 19 patients (30.2%) during the course of the study. However, the deterioration in LAVVR function occurred primarily between 12 and 24 months postoperatively. After the initial 24 postoperative months, LAVVR worsened on only 8 occasions and in each instance worsened by only 1 grade. Deterioration more than 3+ LAVVR occurred in only 3 patients. And deterioration to 4+ LAVVR was not observed after the initial 24 postoperative months but one. Survival curve analysis predicted a 88.2% of ten-year freedom rate from development of 4+ LAVVR after initial operation of complete AVSDs. Conclusion: Postoperative LAVVR remains fairly stable following AVSDs repair, Serious deterioration is rare after 24 postoperative months, especially after the initial 48 postoperative months. But serial follow-up study with echocariogram was need till 24 postoperative months after repair of complete AVSDs.

• Journal of Chest Surgery
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• v.30 no.7
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• pp.656-662
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• 1997

Aortic valvuloplasty has recently gained attention as an attractive alternative procedure for aortic valvular disease. Between March 1995 to August 1996, 14 patients with pure aortic regurgitation(AR) underwent aortic alvuloplasty using leaflet extension with glutaraldehydepreserved autologous pericardium. There were 11 males and 3 females, and the mean age was 34.8 $\pm$ 15.3 years. Preoperative echocardiography and cardiac catheterization revealed that the degree of AR was mean 3.4$\pm$0.65, and more than moderate degree of mitral regurgitation(MR) were detected in 4 patients. In 12 patients, 3 leaflets were extended and in another 2 patients only one deformed leaflet was extended. Concomitant mitral valvuloplasty (MVP) was performed in 4 patients. The competency of the aortic valve after completion of repair was evaluated by the transesophageal echocardiography in operating theater, and there was no aortic and mitral stenosis or regurgitation. In an early postoperative echocardiography, trivial AR was detected in 3 patients and mild MR in 1 patient. The end-systolic and end-diastolic dimensions of the left ventricle were decreased significantly(p<0.05) as compared with those of preoperative values. T ere was no mortality and no significant postoperative complication encountered. Late complication developed in 2 patients during the follow-up period(mean 7.9$\pm$ 5.9 months). One patient underwent AVR on postoperative 7th month due to endocarditis, and the another patient with Behcet's disease underwent Ross operation at postoperative 4th month. In conclusion, AVP of leaflet extension technique offers an excellent early clinical result and represents a good alterna!ivy surgical treatment for the pure AR especially in young age group, although long-term follow-up is necessary to determine the durability of glutaraldehyde-preserved autologous pericardium as a valve leaflet.

• Journal of Chest Surgery
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• v.39 no.4 s.261
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• pp.275-280
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• 2006

Background: Aortopulmonary window (APW) is a very rare congenital heart anomaly, often associated with other cardiac anomalies. It causes a significant systemic to pulmonary artery shunt, which requires early surgical correction. Accurate diagnosis and surgical correction will bring good outcomes. The purpose of this study was to describe our 20-year experience of aortopulmonary window. Material and Method: Between March 1985 and January 2005, 16 patients with APW underwent surgical repair. Mean age at operation was $157.8{\pm}245.3$ ($15.0{\sim}994.0$) days and mean weight was $4.8{\pm}2.5$ ($1.7{\sim}10.7$) kg. Patent ductus arteriosus (8), atrial septal defect (7), interruptedaortic arch (5), ventricular septal defect (4), patent foramen ovate (3), tricuspid valve regurgitation (3), mitral valve regurgitation (2), aortic valve regurgitation (1), coarctation of aorta (1), left superior vena cavae (1), and dextrocardia (1) were associated. Repair methods included 1) division of the APW with primary closure or patch closure of aorta and pulmonary artery primary closure or patch closure (11) and 2) intra-arterial patch closure (3). 3) Division of the window and descending aorta to APW anastomosis (2) in the patients with interrupted aortic arch or coarctation. Result: There was one death. The patient had 2.5 cm long severe tracheal stenosis from carina with tracheal bronchus supplying right upper lobe. The patient died at 5th post operative day due to massive tracheal bleeding. Patients with complex aortopulmonary window had longer intensive care unit and hospital stay and showed more morbidities and higher reoperation rates. 5 patients had reoperations due to left pulmonary artery stenosis (4), right pulmonary artery stenosis (2), and main pulmonary artery stenosis (1). The mean follow-up period was $6.8{\pm}5.6$ (57.0 days$\sim$16.7 years)years and all patients belonged to NYHA class 1. Conclusion: With early and prompt correction of APW, excellent surgical outcome can be expected. However, optimal surgical method needs to be established to decrease the rate of stenosis of pulmonary arteries.

• Journal of Chest Surgery
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• v.47 no.4
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• pp.344-349
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• 2014

Background: The Damus-Kaye-Stansel (DKS) procedure is a method for mitigating the risk of systemic ventricular outflow tract obstruction (SVOTO). However, there have been few reports on which surgical technique shows a better outcome. The objective of this study was to compare the outcome of the DKS procedure according to the surgical technique used. Methods: We retrospectively reviewed 12 consecutive patients who underwent the DKS procedure from March 2004 to April 2013. When the relationship of the great arteries was anterior-posterior, the double-barrel technique (group A) was performed. If the relationship was side-by-side, the ascending aortic flap technique (group B) was performed. Results: There was no early mortality and 1 late mortality in group B. There was no statistically significant difference in the median peak pressure gradient of preoperative subaortic stenosis in both groups: 14 mmHg (range, 4 to 53 mmHg) in group A and 15 mmHg (range, 0 to 30 mmHg) in group B (p=0.526). Further, a significant postoperative pressure gradient was not observed in either group A or group B. More than moderate postoperative neoaortic regurgitation was observed in 1 patient of group B; this patient underwent neoaortic valve replacement 66 months after the DKS procedure. No one had a recurrent SVOTO during follow-up. Conclusion: The DKS procedure is an effective way to minimize the risk of SVOTO, and there is little difference in the outcomes of the DKS procedure according to the surgical technique used.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.381-387
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• 2017

Dehydrogenation from the hydrolysis of a sodium borohydride ($NaBH_4$) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.％) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a $NaBH_4$ solution over both a single microchannel with a hydraulic diameter of $300{\mu}m$ and a staggered array of micro pin fins in the microchannel with hydraulic diameter of $50{\mu}m$. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.％. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.48-55
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• 2011

Hydraulic excavator is one of the most widely used heavy machines in construction sites including dismantling. In the dismantling sites, the excavators equipped with crusher or breaker carry out dangerous operations, so drivers are always exposed to unexpected danger. For safety operation, remote control of the hydraulic excavator has been studied using proportional control valve, which requires an appropriate motion control of its bucket tip. In this case, kinematics and dynamics analysis have to be preceded through modeling of excavator. However, it is difficult to acquire reasonable results from the analysis due to insufficient information of physical parameters such as mass of each links and locations of mass centers, etc. This study deals with the trajectory control of bucket tip, which is based on experimental estimation of cylinder output force. The estimated forces are fed into the control of each cylinder in order to compensate gravitational and frictional effects in the cylinders. The control was applied to horizontal trajectories that are for flattening work.

• Journal of Chest Surgery
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• v.10 no.2
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• pp.299-314
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• 1977

Clinical experience on 16 cases of open heart surgery under the extracorporeal circulation with mild or moderate hypothermia and partial hemodilution technique at the National Medical Center during the period from June 1976 to October 1977. Nine of sixteen were congenital heart disease and seven were acquired heart disease. The age of the patient ranged between 6 and 48 years. The body weight varied from 18.5kg to 60kg and body surface area 0. 79-1.70m2. The average priming volume of pump oxygenator was 2080 ml, which was consisted fresh ACD blood, buffered Hartmann`s solution, Mannitol, 50% dextrose in water and Vit. C. The average hemodilution rate was 27%. The average flow 2.3 L/min/m2 or 80 ml/min and the duration of perfusion varied from 31 min to 270 min with average of 107 min. The perfusion was carried out under the mild or moderate hypothermia using core cooling alone in 10 cases, core cooling and local myocardial cooling with $0-4^{\circ}C$ physiologic saline in 2 cases. From a hemodynamic point of view, the blood pressure dropped down around 80 mmHg after the initiation of perfusion follwed by increase to safety level and stable during the perfusion. The central venous pressure remained within normal limits. In most cases, hemoglobin and hematocrit decreased during and after the perfusion. Hemogiobin level was decreased, average of 20.6 %, hematocrit 18.6%, pletelets 55% postoperatively. Plasma hemoglobin increased moderately, from preperfusion average valve of 7.79 mg % to post-perfusion value of 54.7 mg %. Electrolytes changes during cardiopulmonary bypass showed definite hypokalemia but changes of Na, Ca were not definite. Arterial blood gas analysis during cardiopulmonary bypass suggested that the metabolic acidosis which was accompanied by respiratory alkalosis which was corrected postoperatively. As the opera tive complication, transient hemoglobinuria in 4 cases and neurological signs in 2 cases were all cured. There were 2 death cases and operative mortality rate was 12.5%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.1
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• pp.32-37
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• 2011

The present study has been conducted to propose an algorithm regarding real-time load estimation of a gas engine-driven heat pump. In the study, thermal load of an indoor unit is estimated in terms of air-side and refrigerant-side. The air-side estimation is based on a typical heat exchanger model and is found to be in good agreement with experimental data. When it comes to the refrigerant-side load, a pressure difference across a valve must be estimated. For the estimation, it is assumed to be proportional to a bigger pressure difference that is available either by measurement or by estimation. Relative good agreement between the air- and refrigerant-sides suggests that the assumption may be plausible for the load estimation. The summed flow rate of all of indoor units is in good agreement with the throughput of the compressor which are calculated from the manufacturer's software. Accordingly, estimated thermal loads are also in good agreement. The proposed algorithm may be further developed for improved control algorithm and fault diagnosis.

• Journal of Chest Surgery
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• v.25 no.3
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• pp.232-239
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• 1992

Acute renal failure is a well known serious complication following open heart surgery and is associated with a significant increase in morbidity and mortality rate. From 1984 to 1990, 33 patients who had acute renal failure following cardiopulmonary bypass received renal replacement therapy. PD[Peritonial dialysis] was employed in 11 patients and CAVH[continous arteriovenous hemofiltration] was employed in 22 patients. Their age ranged from 3 months to 64 years[mean 25.5$\pm$7.8 years]. The disease entities included congenital cardiac anomaly in 18, valvular heart disease in 15 and aorta disease in 2 cases. Low cardiac output was thought as a primary cause of ARF except two redo valve cases who showed severe Aemolysis k depressed renal function preoperatively. Mean serum BUN and creatinine level at the onset renal replacement therapy were 65$\pm$8 mg/dl and 3.5$\pm$0.4 mg/dl respectively, declining only after reaching peak level 7&10 days following the onset of therapy. Overall hospital mortality was 72.7%[24/33]; 81%[9/11] in PD group and 68.2% [15/22] in CAVH group respectively. The primary cause of death was low cardiac output & hemodynamic depression in all the cases. The fatal complications included multiorgan failure in 7, disseminated intravascular coagulation and sepsis in 6, neurologic damage in 4 and mediastinitis in 3 cases. No measurable differences were observed between CAVH and PD group upon consequence of acute renal failure and disease per se. The age at operation, BUN/Cr level at the onset of bypass and highest BUN/Cr level and the consequence of low output status were regarded as important risk factors, determining outcome of ARF and success of renal replacement therapy. Thus, we concluded that althoght the prognosis is largely determined by severity of low cardiac output status and other organ complication, early institution of renal replacement therapy with other intensive supportive measures could improve salvage rate in established ARF patients following CPB.