• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.163-172
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• 2002

The turbine system composed of a nozzle and a rotor is used to drive turbopumps while gas passes through the nozzle, potential energy is converted to kinematic energy, which forces the rotor blades to spin. In this study, an aerodynamic design of a turbine system is investigated using compressible fluid dynamic theories with some pre-determined design requirements (i.e.,pressure ratio, rotational speed, required power etc.) obtained from a liquid rocket engine (L.R.E.) system design. For simplicity of a turbine system, impulse-type rotor blades for open type L.R.E. have been chosen. Usually, the open-type turbine system requires low mass flow rate compared to the close-type system. In this study, a partial admission nozzle is adopted to maximize the efficiency of the close-type turbine system. A design methodology of the a turbine system has been introduced. Especially, a partial admission nozzle has been designed by means of simple empirical correlations between efficiency and configuration of the nozzle. Finally, a turbine system design for a 10 ton thrust level of L.R.E is presented.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.2
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• pp.61-71
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• 2014

A river fishway is a hydraulic structure enabling fish to overcome stream obstructions such as dams and weirs. The main aim of this paper is to investigate the collectibility of upstream-migrating fishes and hydraulic problems in pool-and-weir type fishway which has been established for upstream-migration at Namgang weir in the downstream of Namgang dam, and to grope for improvement measures which pool-and-weir type fishway can be switched to pool-and-partial weir type fishway through hydraulic field experiment. Exsisting fishway had problems which upstream-migrating fishes can not take a rest due to the seiche and vortex phenomena in pools and migrate to upstream because of height difference in entrance pool. In order to prevent hydraulically the seiche and vortex phenomena and establish rest area for fishes in each pool, we carried out hydraulic field experiments. In the fishway, it was to improve pool-and-weir into pool-and-partil weir, to decrease the height difference in entrance pool, and to reduce oriffice velocity of each pool. Also, we investigated fishes collectibility of after improving fishway for 6 days in September 2013. To resolve chronic problems(seiche-vortex phenomena and rest area for fishes), as weirs were remodeled into partial weir only which central part of weirs was part of non-overflow weir, we confirmed results that pool-and-weir type fishway could be switched to efficient pool-and-partial weir type fishway with relatively simple construction and low cost. Type-B which has the closed oriffices and the parts of non-overflow has the ideal conditions, but this conditions are limited to fishway of Namgang weir used in this study. Representative Ice-habor type fishway is pool-and-partial weir type fishway which has together parts of overflow and oriffices, and has excellent ability of upstream-migration. To switch from pool-and-weir type fishway to pool-and-partial weir type fishway, the size of oriffice has to be regulated by the discharge of fishway and the dimension on parts of non-overflow and overflow in weirs. Entrance pool is important facility which upstream-migrating fishes have to not only be collect but also charge with energy. In this study, entrance-pool is temporary and roughly-built, but fishes gather together more than the case of no entrance-pool. In the case of fishway which was protruded to downstream, as entrance of fishway turns toward or parallels to weir, the collectibility of fishway was excellent by attraction water.

• Journal of Chest Surgery
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• v.17 no.2
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• pp.244-249
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• 1984

Surgical treatment of partial endocardial cushion defect was accomplished in Feb. 1984 in this department. The 5 year old male patient had history of frequent upper respiratory tract infection and since his age of 3 years dyspnea on exertion and palpitation were noted but there were no cyanosis and clubbing. A thrill was palpable on the apex and grade IV/IV harsh systolic ejection murmur and diastolic murmur was audible on it. Liver was palpable about 3 finger breadths and no ascites. Chest X-ray revealed increased pulmonary vascularity, moderate cardiomegaly [C-T ratio; 0.69], and enlarged left atrium. EKG showed first degree heart block, RVH, LVH, and LAD. Echocardiogram showed paradoxical ventricular septal movement and abnormal diastolic movement of the anterior leaflet of mitral valve. Right heart catheterization resulted left to right shunt [Qp:Qs:2.1:1 ] and moderate pulmonary hypertension [60/40 mmHg]. Left ventriculogram showed mitral regurgitation [Grade III/IV] and filling of left atrium and right atrium nearly same time. Operative findings were: 1.Primum type atrial septal defect [3x2 cm] 2.Cleft on the anterior leaflet of mitral valve. 3.No interventricular communication and cleft of tricuspid valve leaflet. The mitral cleft was repaired with 4 interrupted sutures. The primum type atrial septal defect was closed with Dacron patch intermittently at endocardial cushion and continuously remainder. The post operative course was uneventful and discharged on 22nd postoperative day in good general conditions.

• Journal of Chest Surgery
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• v.18 no.2
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• pp.299-304
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• 1985

The partial A-V canal defect consist of ostium primum type atrial septal defect with a cleft mitral anterior leaflet. The clinical findings depend upon the site and size of the left-to-right shunt, the degree of A-V valvular regurgitation, and the degree of resultant pulmonary artery hypertension. We experienced 3 cases of similar condition. The data were as follow: 1. Chest P-A showed increased pulmonary vascularity and moderate cardiomegaly with left atrial enlargement. 2. E.K.G. showed left axis deviation, left atrial enlargement, and left ventricular hypertrophy. 3. Right heart catheterization showed significant 02 step up of SVC-RA and left-to-right shunt. 4. Left ventriculogram showed mitral regurgitation and filling of both atrium. Operative findings were as follow: 1. Primum type atrial septal defect [2x2 cm]. 2. Cleft in the anterior leaflet of the mitral vave. 3. No evidence of ventricular septal defect and tricuspid anomaly. Through a right atriotomy with moderate hypothermia, the mitral cleft was approximated with interrupted sutures. The interatrial communication was closed by a patch of Dacron/pericardium. The patch was attached to junction of the mitral and tricuspid valves along the crest of the ventricular septum using interrupted sutures and the other site using continuous sutures. Postoperative course was uneventful and discharged in good general condition except postoperative bleeding in case 3.

• Journal of the Korean Institute of Educational Facilities
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• v.10 no.2
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• pp.15-22
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• 2003

The purpose of this study is to find problems and to provide architectural design standards of the Learning Space Unit(L.S.U.) in Elementary Schools through the Post-occupancy Evaluation(POE). In this study, we found six major problems of the type of the L.S.U. in elementary schools. More than 50% of users expressed dissatisfactions in these items : size, safety, cooling facility, noise, privacy and primary meaning for its original purpose. After the interrelation-analysis, we checked pros and cons about each forms of L.S.U. It is the result of analysis of the layout method in L.S.U. 1) "$8.4m{\times}8.4m$" classroom unit got the highest positive responses 2) "2-classroom type" and "4-classroom type" got higher score than "3-classroom type" 3) "Whole faced type" 1) made more active Multi-space than "Partial faced type" 4) prefered prepared "Open-classroom" to "Closed-classroom" 5) 'Zoning type between L.S.U.s' couldn't influence to user's responses. Designers can consult those informations when they plan a new, remodeling and additional elementary school.

• Journal of Chest Surgery
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• v.12 no.3
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• pp.174-182
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• 1979

This is a report on four cases of successful surgical correction of coarctation of the aorta [COA] in Department of the Thoracic & Cardiovascular Surgery, Hanyang University Hospital. The first case was a postductal type of coarctation of the aorta associated with Patent ductus arteriosus [PDA], Persistent left superior vena cava [LSVC] and richly developed collateral circulation. Blood pressure was measured to be hypertensive at the arm, but hypotensive at the legs. The coarctation of the aorta was corrected with following procedure: Partial resection of the aortic wall with diaphragmatic structure lust above and below the coarctating line of the aorta, and then the defect of the aortic wall was closed by lateral aortographic suture. PDA was closed by ligation procedure. The second case a preductal type of coarctation of the aorta associated with PDA, LSVC, ventricular septal defect [VSD] and poorly developed collateral circulation. Normal blood pressure was measured at the arm, but hypotension was observed at the legs. Correction of coarctation of the aorta was performed under the establishment of tube bypass because of poor collateral circulation. After resection of coarctating short segment, end to end anastomosis was performed without any tension. PDA was closed by division procedure. Simple suture closure of VSD was performed by open heart surgery two weeks after correction of COA. The third case was a long segment COA without any other anomaly. Blood pressure was measured to be hypertensive at the arm, but hypotensive at the legs. Vascular prosthesis was performed using Teflon graft tube after resecting coarctating long segment [6.5 cm] of the aorta. The fourth case was a long segment COA associated with aortic insufficiency and richly developed collateral circulation. Normal blood pressure was measured at the arm, but hypotension was observed at the legs. Vascular prosthesis was performed using Teflon graft tube after resecting coarctating long segment [6.0 cm] of the aorta. Both blood pressure and peripheral pulse on the arm and the legs returned to normal postoperatively in all patients.

• Journal of Chest Surgery
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• v.8 no.2
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• pp.81-88
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• 1975

Up to October 31, 1975, 34 cases of atrial septal defect, secundum type, operated in this department, were presented. This is 23.2% of all congenital heart diseases, operated utilizing cardiopulmonary bypass, in this department during this period [34 out of 146]. Out of 34 cases, 32 cases are pure ostium secundum type and one case is sinus venosus and another one is ostium secundum type with partial anomalous pulmonary venous drainage. Six cases of endocardial cushion defect and 3 cases of trilogy of Fallot are excluded in this report. All 34 cases are repaired under direct vision utilizing extracorporeal circulation. Among 34 cases of atrial septal defect, 16 cases are male, and 18 cases are female. Their ages range between 3 to 48 years, but over 59% of the cases are below the ages of 20 years. Thirty-two cases are repaired by direct sutures while 2 cases are repaired with Teflon patches. The average perfusion time is 30 minutes; the shortest 12 and the longest 81 minutes. The number of the defect is single in 31 cases, double in 2 cases, triple in one case. But the associated defect except the main defect are so small as can be closed by simple direct suture. The size of the defect is average $12cm^2$; the smallest 0.7 and the largest $25cm^2$. The surgical mortality is 2 cases [5.6%] and other cases are found to be excellent in the follow up studies.

• Journal of Chest Surgery
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• v.17 no.4
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• pp.657-665
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• 1984

Thirty-seven patients had undergone repair of a endocardial cushion defect between 1977 and Aug. 1983 in Seoul National University Hospital. Twenty eight had a partial defect, one intermediate defect and eight complete endocardial cushion defect. Tricuspid cleft was found in 4 cases and mitral cleft was in all p-ECD. Seven patients were of type C anatomy in c-ECD. Four patients had associated major anomalies, including three TOF in c-ECD, one coarctation in p- ECD. In p-ECD patients, the septal defect was closed with patch in all cases and the atrioventricular valvular insufficiency was corrected with MVR in 4 cases, TVR in 1 case and simple interrupted sutures in remainders. In c-ECD patients the septal defect was closed with single patch except one case. The atrioventricular valve was repaired with simple interrupted sutures except one MVR and TVR case. The operative mortality was 14.2% in p-ECD, 44.4% in c-ECD, but recent 3 years [1980-1983] mortality was 8.7% in p-ECD, 20% in c-ECD. More than grade III systolic regurgitant murmur was oted postoperatively in 4 cases of c-ECD and 3 cases of p-ECD. The operative risk factors were preoperative NYHA classification, cyanosis, Rp/Rs, systolic pressure of main pulmonary artery and the degree of regurgitation of atrioventricular valves. The causes of death were low cardiac output syndromes, pulmonary complications and arrhythmias.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.1
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• pp.39-46
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• 2008

The loss coefficient of the butterfly valve which allows partial opening of the valve at closed position and is applicable to the small-sized pipe system with the diameter of 1 inch was measured for the variation of the valve disk blockage ratio. Two different types of the valve disk configuration to adjust the blockage ratio were considered. One was the solid type valve disk of which the diameter was changed into the smaller size rather than the pipe diameter, and the other was the perforate type valve disk on which some holes were perforated. The results from two types of valve disk were compared to identify their characteristics in the loss coefficient distributions. The loss coefficient and the controllable angle of the valve disk were decreased exponentially with the decrease of the blockage ratio. In addition, the perforate valve disk had the effect on the higher loss coefficient rather than the solid type valve disk.

• International Journal of Reliability and Applications
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• v.7 no.1
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• pp.41-53
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• 2006

The exact cause of the system's failure is often unknown in the masked system lifetime data. In such type of data, there are two observable quantities, namely (i) the systems time to failure and (ii) the set of systems components that contains the component, which might cause the system to fail. Our objective in this paper is to use the maximum likelihood procedure in the presence of masked data to make inference for the reliability of the system's components. We assume a multi-component series system where each component has a constant failure rate. Different cases that permit for closed form solutions of point estimates are considered. The results obtained in this paper generalize other published results.