• Journal of Advanced Marine Engineering and Technology
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• 제17권3호
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• pp.33-41
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• 1993

양벽면 모두 사각돌출형조도요소가 설치된 동심 이중관내에서 생기는 비대칭 난류유동과 열전달 특성을, 열전달과 마찰계수에 미치는 조도의 합성효과를 조사하기 위해, 연구하였다. 이론해석에서는 한쪽면에 거칠기가 있는 평행평판의 유동에 대한 수정 플란틀 혼합길이(mixing length)이론의 난류 모델을 속도분포와 마찰계수를 구하는데 사용하였다. 최대속도지점에서 안쪽과 바깥쪽의 두 속도형상들은 힘의 평형에 의해 일치시켰다. 그리고 나서, 온도 분포와 열전달 계수를 계산하였다. 속도형성과 마찰계수들의 해석결과는 실험과 매우 잘 일치하였다. 마찰계수와 Nusselt number에 미치는 조도비, 조도에 대한 피치비, 그리고 반경비등과 같은 여러 변수들의 효과들을 조사하였다. 본 연구는 일정의 조도 요소들이 전체적 효율 측면에서 볼때 유리하게 열전달을 향상시킨다는 것을 증명하였다.

• 대한기계학회논문집
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• 제11권1호
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• pp.88-96
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• 1987

본 논문에서는 Maubach의 방법에 내재된 불합리한점을 보완하고자 Fig.1(b)와 같이 .iota.=0인 곳에서 속도구배를 ㄹ변환하여 마찰계수와 조도함수를 계산하였다. 이 방법에 의해 얻어진 속도분포에서는 .iota.=0인 곳에서 속도구배에 불연적성이 일어나지 않는다.

• 동력기계공학회지
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• 제4권2호
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• pp.17-24
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• 2000

직경비가 0.26, 0.39, 그리고 0.56인 경우 거칠기를 내벽면에, 외벽면에, 그리고 양벽면에 각각 설치한 동심환형관에서 완전히 발달된 난류유동에 대한 거칠기 효과를 실험과 이론으로 해석하였다. 그리고 거칠기 효과를 정량적으로 파악하기 위해 양벽면 모두 매끈한 환형관의 경우도 포함하였다. 실험에서 마찰계수를 구하는데 필요한 속도분포와 전단응력들은 피토튜브와 X-형 열선풍속계를 사용하였다. 이론 해석은 수정대수 난류모델을 사용하였고 그 결과를 이론값과 비교하여 아래의 결론을 얻었다. 1) 무디다이어그램 (Moody diagram)은 거칠기가 설치된 이중관에는 적용할 수 없음을 보였다. 2) 경우(c) 와 (d)에서는 반경비가 클수록 반드시 마찰계수가 증가하지 않았다. 3) 4개의 경우중 거칠기로 인해 마찰계수가 증가하는 크기의 순서는 경우(d)가 가장 컸고 경우(a)가 가장 작았다.

• 대한수의학회지
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• 제48권4호
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• pp.481-487
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• 2008

A 17-month-old intact male Cocker Spaniel was presented with primary complaints of severe ascites, exercise intolerance, and diarrhea. Diagnostic studies revealed tricuspid and pulmonic regurgitation on phonocardiogram, right ventricular enlargement on the electrocardiogram, typical right cardiac enlargement signs on the thoracic radiography and tricuspid valve malformation and marked enlargement of the right atrium and right ventricle on the echocardiography and tricuspid and pulmonary regurgitation on the color spectral echocardiography, suggesting tricuspid valve dysplasia and pulmonary hypertension. Using angiography and cardiac catheterization, pulmonary hypertension was ruled out. Further echocardiographic study revealed membranous valvular structures cranial to pulmonary annulus causing pulmonary regurgitation. Based on these findings on the diagnostic investigation, the case was diagnosed as tricuspid valve dysplasia complicated with pulmonic regurgitation. The dog was medically managed with furosemide, enalapril, nitroglycerine transdermal patch and pimobendan after the ascitic fluid removal.

• Journal of Chest Surgery
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• 제12권1호
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• pp.43-49
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• 1979

This is a case report of surgically treated rupture of Valsalva Sinus aneurysm combined with VSD. He has been relatively healthy until about one month before admission, when during bath, he felt abruptly palpitation, left chest pain and exertional dyspnea. These symptoms have progressed. On admission, thrill was palpable and continuous machinery murmur was audible on 2nd and 3rd intercostal space along the left sternal border. A rupture of Valsalva`s sinus aneurysm was confirmed by aortography and echocardiography but a small VSD was found by cardiotomy in open heart surgery. On 11th Sep. 1978, open heart surgery was performed. Valsalva`s sinus aneurysm came out from right coronary aortic sinus and ruptured into the right ventricle. It sized 1.2X1.5X1.5 cm. Ruptured opening was noted on apex of aneurysm [0.8X0.8cm], VSD [1. 0X0. 3cm in size] was just below the aortic annulus. The aneurysmal sac was removed on neck. After that, VSD and aneurysmal orifice were closed together with interrupted mattress sutures on same plane. The postoperative course was uneventful and discharged three weeks after open heart surgery.

• Journal of Chest Surgery
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• 제24권5호
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• pp.491-497
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• 1991

Coronary arteriovenous fistula is a relatively rare congenital heart disease and it drains into right atrium, right ventricle, pulmonary artery, coronary sinus or superior vena cava. We experienced one case of fistulous communication between right coronary artery and right ventricle which was most common condition. The patient was a 12 year old female and the only sign was continuous cardiac murmur. The cardiac catheterization and coronary angiography showed the fistulous communication between right coronary artery and right ventricle and aneurysmal dilatation of right coronary artery. Under the cardiopulmonary bypass with the hypothermic cardioplegia, fistula opening[7mm] which was located at right ventricle below the tricuspid valve annulus between septal and posterior leaflet was closed with 4 - 0 prolene continuous suture through right ventriculotomy. Her postoperative course was uneventful.

• Journal of Chest Surgery
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• 제21권6호
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• pp.1145-1151
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• 1988

Supraventricular tachyarrhythmias are readily characterized and understood, but the surgical procedures for their correction are complex and not easily mastered. Conversely, ventricular tachyarrhythmias are frequently difficult to characterize and localize electrophysiologically and their basic mechanisms are poorly understood. The role of the surgeon in the treatment of cardiac arrhythmia has changed dramatically during the past decade. This report is a case of 26 years old male with supraventricular tachyarrhythmia. The result of endocardial electrophysiologic study demonstrated accessory pathway connecting left atrium to left ventricle which located at left atrial free wall about 4 cm apart from the coronary sinus orifice. The accessory bundle interruption has been successfully accomplished utilizing the internal open heart technique. The operation consisted of dissection of the atrioventricular fat pad and division of all the superficial fibers going from the ventricle to the annulus. Following this, cryoablation made with cryoprobe at - 60` for 90 seconds. The accessory pathway was successfully ablated without specific problems.

• Journal of Chest Surgery
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• 제21권5호
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• pp.882-888
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• 1988

A case of Annuloaortic Ectasia associated with Marfan syndrome and mitral regurgitation is treated surgically by Bentall`s method and mitral annuloplasty. The Annuloaortic Ectasia is frequently accompanied with Marfan syndrome, its definition is simply explained as the following; the marked dilatation of the sinuses of Valsalva and the aortic annulus as well as the huge aneurysm of the ascending aorta. As the operative finding, the intimal tearing was shown as circular and the both coronary ostia were changed the position into high up. The patient was taken a corrective operation replacing the ascending aorta and aortic valve with a composite graft[St. Jude medical valve 29mm, woven Dacron tubular graft 31mm]. The both coronary ostia were reimplanted on the graft with 4-0 prolene by continuous suture. Mitral annuloplasty was performed. After the operation, the patient developed both spontaneous pneumothorax, he improved state by the closed thoracostomy. He has been doing well, postoperatively.

• 소음진동
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• 제7권4호
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• pp.613-620
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• 1997

Steady and unsteady flows between rotating cylinders are of interest on lubrication, convective heat transfer and flow-induced vibration in large rotating machinery. Steady rotating flow is generated by rotating cylinder with constant velocity while the unsteady rotating flow by oscillating cylinder with homogeneoysly oscillating velocity. An analytical method is developed based on the simple radial coordinate transformation for the steady and unsteady rotating flows in concentric annulus. The governing equations are simplified from Navier-Stokes equatins. Considering the skin friction based on the radial variation of circumferential flow velocity, the torques acting on the fixed and the rotating cylinder are evaluated in terms of added-inertia and added-damping torque coefficients. The coefficients are found to be influenced by the oscillatory Reynolds number and the radius ratio of two cylinders; however, the effect of the oscillatory Reynolds number on the coefficients is minor in case of relatively low radius ratio.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.799-800
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• 2004

한전전력연구원에서는 한국표준형 원전 증기발생기인 시스템 80 모델의 튜브시트 상부에 침전된 슬러지를 제거하기 위한 고압 분사식 슬러지 세정장비를 개발하였다. 국내에는 영광 3,4,5,6 호기 및 울진 3,4,5,6 호기 등 총 8 기의 한국표준형 원전이 운전중에 있으나 기 사용하고 있던 증기발생기 세정 장비가 자동화가 미흡하여 작업자의 방사선 쪼임량이 과대하고 장비가 전열관에 충돌하여 전열관이 손상될 가능성이 상존하며 세정 방식이 증기발생기 가장자리인 annulus 에서 중앙의 center stay cylinder 로 향해 슬러지가 증기발생기 중앙 부분에 집중적으로 침적될 가능성이 있는 등 문제점을 해결하기 위하여 개발에 착수하였다. 개발된 증기발생기 세정 장비는 2004 년 4 월 중 울진 3 호기 증기발생기 세정 작업에 성공적으로 활용되었다.