• 수산해양기술연구
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• 제33권3호
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• pp.202-208
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• 1997

The component materials threatened by cavitation include ship propellers as well as turbine runners, pump impellers, pipe lines and radiators. Today it is known that cavitation damage takes place on many other components including on the coding water side of the cylinder liners of diesel engines. Cavitation erosion - corrosion implies damage to materials due to the shock pressure or shock wave that results when bubbles form and collapse at a metal surface within a liquid. To suppress cavitation erosion as well as cavitation erosion - corrosion to hydraulic equipment, innovations such as the improvement in the geometric design of the equipment or the selection of suitably resistant construction materials are necessary. In this study, we investigated that the cavitation erosion - corrosion damage under vibratory cavitation can be reduced by adding of side now velocity to the cavitation bubble group in order to eliminate bubbles formed in sea water environment.

• Journal of Chest Surgery
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• 제22권3호
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• pp.402-415
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• 1989

Extracorporeal circulation leads to functional disorder and structural damage of organs, especially hematologic and pulmonary system, mainly by sequestration of neutrophils and deposition of macrophages at lung. Then, proteases are secreted, which insult vascular basement membrane of pulmonary capillary and alveolar septa of the lung. Among these, the most important protease at lung is elastase, because major component of lung is elastin. For prevention of lung injury, inactivators or antidotes to elastase should be necessary and Alpha 1-Proteinase Inhibitor is the elastase inactivator. Clinical experimental study was carried out to investigate the immediate postoperative change of serum Alpha 1-PI level following cardiopulmonary bypass for 20 heart cases [congenital 16 cases, acquired 4 cases] and 10 control [subtotal gastrectomy] cases. Also preliminary study was performed for 31 cases of open heart patients. The results were as follows: l. Immediate postoperative serum levels of Alpha 1-PI was significantly decreased at open heart surgery group [P< 0.005], but not decreased at control group. 2. There were no significant difference in change of serum Alpha 1-PI level between and membrane and bubble oxygenator group.Z 3. There were no significant difference in changes of serum Alpha 1-PI level between CHD and AHD. Alpha 1-PI is consumed at lung during cardiopulmonary bypass and increase after operation compensatedly and protect multiple organic damage especially lung. Therefore, Alpha 1-PI can be indicator for evaluation of prevention and treatment of pump-lung syndrome.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.447-450
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• 2012

30톤급 터보펌프-가스발생기 연계시험에서 예냉 절차에 대해 분석을 수행하였다. 예냉은 극저온 추진제를 사용하는 액체로켓엔진에서는 시험 전 반드시 수행하여야 하는 절차이다. 예냉을 통해 시험기, 특히 극저온 펌프의 온도를 극저온으로 낮춰 펌프의 공동화 현상, 베어링 부의 파손, 기포에 의한 연소 불안정성의 가능성을 사전에 제거한다. 30톤급 터보펌프-가스발생기 연계시험을 통해 수집한 자료를 분석함으로서 한국형발사체 엔진 개발 시험 시 유용한 자료로 사용하고자 연구를 수행하였으며, 각 주요 부위의 온도, 예냉 수행 시간 등을 파악하였다.

• Journal of Chest Surgery
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• 제23권5호
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• pp.864-870
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• 1990

This study was undertaken to evaluate current technique of extracorporeal circulation by analyzing the results in 73 cases. We performed standard cardiopulmonary bypass using Polystan roller pump, bubble[Polystan] and membrane[Cobe] oxygenator. There were 42 males and 31 females. We studied the changes of hemoglobin. hemodynamics, speed of cooling and warming, methods of cannulation and ACT. Arterial cannula was inserted on ascending aorta except for 7 cases of femoral cannulation. Preoperative hemoglobin was 13.2 gm% and this value dropped to 7.5 gm% during perfusion. Blood pressure of 113 mmHg in systolic dropped 57mmHg in 10 minutes of perfusion and became 98 mmHg at the end of perfusion. Initial drop of blood pressure was marked in pediatric patient. Mean cooling time was 19.4 min[0.54 Q /min] and warming time was 34 minutes[0.25 Q /min]. During perfusion, ACT was maintained above 600 sec and 44 patient did not need additional Heparin.

• 대한조선학회논문집
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• 제60권5호
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• pp.296-304
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• 2023

Cavitation tests for a waterjet propulsor of an amphibious vehicle are carried out in the Large Cavitation Tunnel. Waterjet pump performances and cavitation characteristics including thrust breakdown performances are investigated in the tests. In addition, cavitation characteristics for waterjet propulsors working inside the intake are calculated by using a commercial CFD code, Star-CCM+. Sliding mesh is implemented to a rotating impeller and the k-epsilon turbulence model is chosen. Cavitation bubble growth and collapse are estimated using the Schnerr-Sauer cavitation model based on Rayleigh-Plasset equation. Calculated results agree fairly well with experimental results. The re-design of the waterjet propulsor is performed to enhance waterjet cavitating performances and calculated results show that waterjet thrust breakdown characteristics are significantly improved.

• 한국군사과학기술학회지
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• 제18권3호
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• pp.213-219
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• 2015

Piezoelectric-based hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by piezoelectric stacks that is coupled to a conventional hydraulic cylinder via a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, a piezoelectric hybrid actuator has been designed and tested. To achieve bi-directional capabilities in the actuator, solenoid valves were used to control the direction of output fluid. The experimental testing of the actuator in uni-directional and bi-directional modes was performed to examine performance issues related to the solenoid valves. The results showed that the bi-directional performance was slightly lower than uni-directional performance due to air bubble developed in the valve system. A new design to solve the vacuum problem has been proposed to improve the performance of the hybrid actuator.

• Journal of Chest Surgery
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• 제19권4호
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• pp.644-662
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• 1986

Seventy cases of open heart surgery were performed in the department of Thoracic and Cardiovascular Surgery, Pusan Paik Hospital, Inje College, from Oct. 1985 to Oct. 1986. And the results were summarized as follows. 1. Among the 70 cases, there were 48 cases of congenital heart anomalies and 22 cases of acquired rheumatic valvular heart diseases. Age range of the congenital patients was 7 months to 31 years with the mean age of 10 years, and the acquired patients was 18 to 62 years with the mean age of 40 years. 2. The heart-lung machine used for cardiopulmonary bypass was Sarns 7000, 5-head roller pump, and the number and type of oxygenators were 5 of membrane type and 65 of bubble type. For all cases GIK [glucose-insulin-potassium] solution was used as cardioplegic solution for myocardial protection during operation. 3. Among the 48 congenital anomalies, there were 12 cases of ASD group, 29 of VSD group, 3 of ECD, 3 of TOF and one of PDA + MR, and to all of which the appropriate radical operations were applied. 4. Among the 22 acquired valvular diseases, there were 11 cases of mitral valve diseases [MS; 4, MSr; 3, MRs; 4], 3 cases of aortic valve diseases [AR:1, ARs;1, ASr;1], 4 cases of double valve diseases [MRs+TR; 3, MRs+ARs; 1] and 4 cases of triple valve diseases [MSr+ASr+TR; 3, MSr+Ar+TR; 1]. To all the diseased mitral and aortic valves, artificial valve replacement was applied except one [As], in which valve plication was applied. And to all the diseased tricuspid valve, DeVega annuloplasty was applied. 5. The number of replaced artificial valves were 29 in 25 patients [congenital; 3, acquire; 22]. In MVR, 6 of mechanical valves [St. Jude Medical valve; 6] and 15 of tissue valves [Carpentier-Edward valve; 11, lonescu-Shiley valve; 4] were used. In AVR, 6 of mechanical valves [St. Jude Medical valve; 6] and 2 of tissue valves [Carpentier-Edward valve; 2] were used. 6. Postoperative complications were occurred in 12 cases. Among them 11 cases were recovered with intensive cares, but one patient [VSD + Fistula of Valsalva sinus] was expired with low cardiac out put syndrome.

• Journal of Chest Surgery
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• 제21권2호
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• pp.351-365
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• 1988

During one year[1987], 110 cases of open heart surgeries were performed in the department of Thoracic and Cardiovascular Surgery, Pusan Paik Hospital, Inje Medical College. And the results were summarized as follows. 1. Among the 110 cases, there were 77 cases of congenital heart diseases and 33 cases of acquired heart diseases. Age range of the congenital patients was 8 months to 30 years with the mean age of 8 years, and acquired patients was 16 to 56 years with the mean age was 32 years. 2. The heart lung machine used for cardiopulmonary bypass was Sarns 7000, 5-head roller pump, and the number and type of oxygenators were 50 of membrane type and 60 of bubble type. For all cases GIK[glucose-insulin-potassium] solution was used as cardioplegic solution for myocardial protection during operation. 3. Among the 77 congenital anomalies, there were 67 cases of acyanotic patients[ASD: 12, VSD: 50, PS: 1, AP window: 1, Gerbode defect: 1, ECD: 2] and 10 cases of cyanotic patients[TOF: 10], and to all of which the appropriate radical operations were applied. 4. Among the 33 acquired diseases, there were one case of left atrial myxoma, one of annuloaortic ectasia, 20 of mitral valve diseases[MS: 2, MSr: 8, MR: 2, MRs: 8], 9 of double valve diseases[MRs+AR: 1, MRs+ARs: 2, MRs+TR: 1, MSr+TR: 3, MSr+ASr: 1, MSr+ARs: 1], 2 of triple valve diseases[MSr+AR+TR: 1, MSr+ASr+TR: 1]. The left atrial myxoma was removed well with right atriotomy and atrial septal approach. And to the annuloaortic ectasia, Bentall operation was applied with good result. Mitral valve replacement[MVR] was applied to 20 cases of mitral valve diseases, double valve replacement[MVR+AVR] was applied to 6 cases of double valve diseases, MVR & tricuspid annuloplasty[TVA] was applied to 3 cases of mitral 5. The number of replaced valve were 39 in 31 cases. In MVR, 5 of mechanical valves[St. Jude Medical Valve] and 26 of tissue valves[Carpentier-Edward valve] were used. In AVR, 3 of mechanical valves and 5 of tissue valves were used. 6. Postoperative complications were occurred in 23 cases, and among them 21 cases were recovered with intensive cares, but 2 cases were expired[mortality: 1.8%].

• 한국초전도ㆍ저온공학회논문지
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• 제16권4호
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• pp.66-70
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• 2014

The superconducting fault current limiter (SFCL) is an electrical power system device that detects the fault current automatically and limits the magnitude of the current below a certain safety level. The SFCL module does not have any electrical resistance below the critical temperature, which facilitates lossless power transmission in the electric power system. Once given the fault current, however, the superconducting conductor exhibits extremely high electrical resistance, and the magnitude of the current is accordingly limited to a low value. Therefore, SFCL should be maintained at a temperature below the critical temperature, which justifies the cryogenic cooling system as a mandatory component. This report is a study which reported on the cooling system for the 154 kV-class hybrid SFCL owned by Korea Electric Power Corporation (KEPCO). Using the cryocooler, the temperature of liquid nitrogen (LN2) was lowered to 71 K. The cryostat was pressurized to 5 bars to improve the dielectric strength of nitrogen and suppress nitrogen bubble foaming during operation of SFCL. The SFCL module was immersed in the liquid nitrogen of the cryostat to maintain the superconducting state. The performance test results of the key components such as cryocooler, LN2 circulation pump, cold box, and pressure builder are shown in this paper.

• 한국물환경학회지
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• 제22권3호
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• pp.534-539
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• 2006

The supply of oxygen for aeration is the largest energy consumer at activated sludge wastewater treatment plants. Replacement of less efficient aeration systems with fine pore aeration devices can save up to 50 percent of aeration energy costs. The purpose of this study was the diagnosis and evaluation of a domestic wastewater aeration system by the off-gas method which had been studied by US EPA and ASCE. For this study, an off-gas analyzer and its hood were made to collect off-gas. Also, a vacuum pump was connected to the analyzer to make suction of off-gas. Experiments were conducted at a domestic activated sludge wastewater treatment plant which had a single spiral roll aeration system installed with P.E tube diffuser. Data on OTE(f), SOTE(pw), OUR, and air flow rate were obtained from these experiments. In case of replacing an aeration system, it is recommended that it should be replaced with perforated membrane disc or ceramic disc fine bubble diffusers installed in a full floor coverage or grid pattern.