• Journal of Chest Surgery
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• v.32 no.3
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• pp.262-269
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• 1999

Background: To review the middle and long term results of aortic valve replacement(AVR) for 11 years, we surveyed and followed up the patients who underwent AVR. Material and Method: Between Feb. 1986 and May 1997, 134 patients underwent AVR. The patients consisted of 71 men and 63 women whose mean age was 38.9 years, ranging from 17 to 70. Result: The concomitant operations were 62 mitral valve replacement(MVR), 14 MVR + tricuspid valve annuloplasty, 10 Cabrol operation, 16 aortic annulus widening, and so forth. We used 119 mechanical(75 St. Jude Medical, 38 CarboMedics, 6 Sorin) and 15 tissue (Carpentier-Edwards) valves. Early postoperative complications occurred in 35 cases; 9 congestive heart failure, 6 low cardiac output, 5 postoperative bleeding, 5 pleural effusion, and so forth. There were 13 early postoperative deaths(9.7%) due to low cardiac output(5), CHF (2), disseminated intravascular coagulopathy(2), and so forth. The cumulative total follow-up period was 452.7 patient-years with a mean of 3.4${\pm}$3.1 years/patient. There were 9 cases of valve-related complications; anticoagulant-related bleeding(4), prosthetic valve endocarditis(2), thromboembolism(2) and prosthetic valve failure(1) occured at rate of 0.9, 0.4, 0.4, 0.2%/ pt-yr, respectively. Late valve-related death occurred in 3 cases(2.0%/pt-yr) associated with anticoagulant-related bleeding(2) and prosthetic valve endocarditis(1). Conclusion: Actuarial survival rate by Kaplan-Meier method was 91.0${\pm}$4.3 % at 11 years.

• Journal of Chest Surgery
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• v.17 no.3
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• pp.346-355
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• 1984

77 cases of Aortic Valve Replacement, which were composed of 64 rheumatic valvular heart disease and 13 combined congenital heart disease, were operated at Seoul National University Hospital for Aortic valvular disease during the period from June 1968 to December 1983. Among these 64 rheumatic aortic valvular heart disease cases, 8 patients were expired during and immediate after operation and overall mortality rate was 12.5%. For more precise remarks, these patients were divided into two periodic groups, 1st period [from 1968 to 1976] and 2nd [from 1977 to 1983] when annual open heart surgery were over 100 cases, and in 1st period three of four patients were died and in 2nd period five of sixty patients were died and its mortality rate was 8.3%. There were 12 cases of postoperative complication, which were 3 cases of remaining other valvular heart disease required MVR, 2 paravalvular leaks [one of them got Redo AVR], 4 thromboembolism or problem of anticoagulant therapy, 2 late death due to SBE with replaced valve failure and one functional AS with small sized valve. Operative death was affected by pump-time and aortic cross-clamping time, heart size, Ejection Fraction, LVEDP and symptom duration, and other many factors may influence the survival rate. Improved operative technique and myocardial protection and meticulous evaluation of the preoperative patient status will make the AVR safer.

• Journal of Chest Surgery
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• v.17 no.3
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• pp.356-361
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• 1984

During the period from January 1982 to June 1984 we implanted permanent pacemakers in 18 patients who received open heart surgery at Yonsei University Hospital. 1.In 11 patients, open heart surgery was performed at Yonsei University Hospital and new surgical induced heart blocks were developed and implantations of permanent pacemaker were done. 2.Total 1035 open heart surgeries were done and implantations of pacemaker were performed in 11 cases. [1.06%]. After total correction of TOF [215 cases] implantations of pacemaker were done in 3 cases. [1.4%] Implantations of pacemaker were 0.37% after VSD repair, 0.78% after ASD repair, 5.9% after ECD repair, 0.48% after MVR and 2.0% after AVR. 3.Causes were complete A-V block, sick sinus syndrome and A-V dissociation. 4.Heart blocks were developed immediately after bypass stop in 8 patients. 5.Implantations of pacemaker were done at more than 2 weeks after open heart surgery. 6.Local anesthesia was done in adult and general anesthesia in infants. Locations of pulse generator were subxiphoid, subcostal & subclavian. Position of pulse generator was between subcutaneous fat layer and muscle layer. 7.Types of pulse generator were VVI, VDD and AAI. 8.The postoperative complications included infection, pacing failure, sensing failure and lead dislodgment.

• Journal of Chest Surgery
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• v.17 no.4
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• pp.557-564
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• 1984

Of the valve replacement patients operated between 1983 and June, 1984, 75 patients need more than 60 minutes of aortic cross-clamping time. 42 patients performed single valve replacement [35 MVR, 7 AVR with or without TAP] and remainder needs double valve replacement with or without TAP. The average aortic clamping time was 95.1 minutes. They need 30 minutes more extra-corporeal circulation time than aortic clamping time. The patients were divided into two groups by usage of cardioplegic solution. Group I [n=31] with Bretschneider solution and group II with potassium cardioplegic solution [M.G.H. modification] were analyzed by extra-corporeal circulation data,/CG and Echocardiography findings, and clinical data. There was no difference between two groups in Bivon addition amounts [cc/kg] and E.F. and S.F. by echocardiography, group I need 1 more electrocardioversion to convert sinus rhythm postoperatively. Also no difference could be found in patients whose preoperative C.I. was above 2.0 between two group. But significant postoperative decrease in E.F. was found in group I whose preoperative C.I. was below 2.0. Relatively longer ECC time was also needed in same group. Ischemic changes in ECG and low cardiac output syndrome was, however more prevalent in groupII. As a whole, the clinical data was satisfactory with both cardioplegic solution in clinical practice.

• Journal of Chest Surgery
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• v.24 no.1
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• pp.26-35
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• 1991

From January 1984 to June 1990, 188 patients have undergone cardiac valve replacement [114 MVR, 27 AVR, 47 Multiple valve replacement] with the St. Jude Medical prosthesis. The early mortality rate was 6.9%. The most common cause of early death was low output syndrome. There were no cases of valve-related early death. The risk factors for early death were advanced preoperative NYHA functional class [> IV], and prolonged ECC and ACC time. The 175 early survivors were followed-up for a total 372.7 patient-year over a period of 2 to 74 months [Mean $\pm$SD: 25.6$\pm$18.6 months]. During follow up, 12 patient died and late mortality rate was 6.9%. There were three valve-related late deaths: two were due to valve thrombosis and one was due to hemorrhage. Most late deaths [58%, 7/12] were from cardiac non-valvular causes. Valve-related complications occurred at a linearlized rate of 3.5% /pt-yr. Embolism occurred at a rate of 0.8% /pt-yr. There were three cases of valve thrombosis [0.8% /pt-yr: two fatal]. Hemorrhage due to anticoagulant occurred in 5 patients and a rate of 1.3% pt-yr [one fatal]. Five-year actuarial survival rate was 86.5 $\pm$5.1% and 97% of patient were in NYHA functional class I or II at three months postoperatively.

• Journal of Chest Surgery
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• v.14 no.3
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• pp.247-253
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• 1981

A total and consecutive 46 patients have undergone cardiac valvular surgery including 8 open mitral commissurotomy and 38 mitral, aortic, mitral-aortic, mitral-tricuspid, tricuspid valve replacements using 46 artificial valves in a period between September 1976 and July 1981. They were 19 males and 27 females with the age ranging from 16 to 50 (mean 32.6) years. Out of 46 valves replaced, 6 were prosthetic valves and 40 were tissue valves, and 33 were replaced in mitral, 9 in aortic and 3 In tricuspid position. Isolated replacements were 33 mitral valves, 6 aortic valves and 1 tricuspid valve; double valve replacements were 6 mitral-aortic valves and 2 mitral-tricuspid valves. . Early mortality within 30 days after operation was noted in 4 cases; 3 after MVR and 1 after open mitral commissurotomy. Causes of death were thrombus obstruction of Beall-Surgitool, Cerebral air embolism, acute renal shut down due to low output syndrome, and left upper pUlmonary vein rupture after open mitral commissurotomy (early mortality 8.7%). 3 late deaths were noted during the follow-up period from 2 to 59 months; 1 due to cerebral hemorrhage from warfarin overdose 3 months, 1 due to miliary tuberculosis 9 months, and another 1 due to cardiac failure after open mitral commissurotomy 42 months postoperatively. Total survival rate 59 months after valvular surgery was 84.8%; there were no early and late death in the group of AVR, TVR and double valve replacements. Preoperative NYHA Class III & IV were 35 cases (76%) out of total 46 cases, and 38 cases (94.8%) out of 39 survival cases were included In NYHA Class I & II during the follow-up period.

• Journal of Chest Surgery
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• v.27 no.8
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• pp.656-663
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• 1994

Evaluation of heart function is of importance in assessing the results of valvular heart surgery. Information on volume and functional change of heart chamber can be obtained by cardiac catheterization and echocardiography. We studied 41 patients with mitral stenosis[MS] and 23 patients with mitral regurgitation[MR] using M-mode echocardiography before and after mitral valve replacement[MVR] at Pusan Paik Hospital. Preoperative cardiac catheterization was available in 56 cases, and the results were obtained as follows. 1. In patients with MS, preoperative average LV end-diastolic dimension[EDD] and end-systolic dimension[ESD] were remained within normal range, but postoperative EDD and ESD were significantly decreased[P<0.01]. The preoperative and postoperative LV ejection fraction[EF] were remained within the normal range and no significant change[P>0.05]. The preoperative left atrial dimension[LAD] was enlarged considerably above normal[P<0.01], but was significantly decreased after surgery[P<0.001]. The preoperative LV posterior wall thickness[PWTh] was within normal range, and no significant change after surgery[P>0.05]. 2. In patients with MR, preoperative average end-diastolic dimension[EDD] and end-systolic dimension[ESD] were significantly greater than normal[P<005], but postoperative EDD and ESD were significantly decreased[P<0.01]. The preoperative LV ejection fraction[EF] and fractional shortening[FS] were within normal range, and no significant change after surgery[P>0.05].The preoperative left atrial dimension[LAD] was enlarged considerably above normal [P<0.01], but was significantly decreased after surgery[P<0.001].The preoperative LV posterior wall thickness[PWTh] was within normal range, and no significant change after surgery[P>0.05].

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.139-147
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• 2016

This study described the design scheme for each step of the production test for the Fire Control System(FCS) of the K-55A1 PIP business of Hanwha Thales since 2011. From the time of receipt of the product It is necessary to improve the FCS's reliability by using the Unit Test, burn-In test, System Test. FCS of K-55A1 acts as a 'head' that control the self-propelled howitzer, and connected with the electrical and physical connection of self-propelled howitzer's multiple unit (Inertial navigation systems(IN), Muzzle Velocity Radar (MVR)) for the normal operation without an inch of error in operating. We designed the production testing equipment automatically as much as possible and designed with the environment similar to the self-propelled howitzer. by using this production testing equipment, It should help for the strengthen national defense of the Republic of Korea.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.33-38
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• 2018

This study applied upgrades to the processes of a 10 MW wet amine $CO_2$ capture pilot plant and conducted performance evaluation. The 10 MW $CO_2$ Capture Pilot Plant is a facility that applies 1/50 of the combustion flue gas produced from a 500 MW coal-fired power plant, and is capable of capturing up to 200 tons of $CO_2$. This study aimed to quantitatively measure efficiency improvements of post-combustion $CO_2$ capture facilities resulting from process upgrades to propose reliable data for the first time in Korea. The key components of the process upgrades involve absorber intercooling, lean/rich amine exchanger efficiency improvements, reboiler steam TVR (Thermal Vapor Recompression), and lean amine MVR (Mechanical Vapor Recompression). The components were sequentially applied to test the energy reduction effect of each component. In addition, the performance evaluation was conducted with the absorber $CO_2$ removal efficiency maintained at the performance evaluation standard value proposed by the IEA-GHG ($CO_2$ removal rate: 90%). The absorbent used in the study was the highly efficient KoSol-5 that was developed by KEPCO (Korea Electric Power Corporation). From the performance evaluation results, it was found that the steam consumption (regeneration energy) for the regeneration of the absorbent decreased by $0.38GJ/tonCO_2$ after applying the process upgrades: from $2.93GJ/ton\;CO_2$ to $2.55GJ/tonCO_2$. This study confirmed the excellent performance of the post-combustion wet $CO_2$ capture process developed by KEPCO Research Institute (KEPRI) within KEPCO, and the process upgrades validated in this study are expected to substantially reduce $CO_2$ capture costs when applied in demonstration $CO_2$ capture plants.

• Journal of Chest Surgery
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• v.35 no.8
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• pp.594-598
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• 2002

Amiodarone is an iodinated benzofuran derivative that has been proved effective in the control of supraventricular and ventricular arrhythmias refractory to other antiarrhythmic drugs. In patients treated with amiodarone, subsequent surgical intervention is a common clinical scenario, but unfortunately we do not have definite data about complications due to amiodarone after cardiac surgery. Some reports have shown that amiodarone treatment can be associated with a state of $\alpha$-adrenergic and $\beta$-adrenergic receptor blockade, which requires more pacing and epinephrine infusion for perioperative hemodynamic support. And some reports have also identified a severe form of ARDS in patients on amiodarone therapy which was associated with siginificant morbidity and mortality. We exprienced a patient who expired after mitral valve replacement due to amiodarone-induced ARDS; therefore, we report this case with a brief literature.