• Journal of Biomedical Engineering Research
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• v.20 no.5
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• pp.601-608
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• 1999

동맥의 일부분의 팽창하는 동맥류는 높은 사망률을 야기하는 혈관계 질환이다. 동맥류의 발생 및 파열에는 동맥류 내부의 혈류의 유동에 의한 혈관벽 전단 응력 및 압력이 주용한 원인 중 하나로 의심되고 있다. 복부대동맥류 내부의 혈류 유동 특성을 밝히기 위해서 동맥류의 최대 확장부가 복부동맥의 1.5배, 2배인 유리 모델을 제작하였다. 정상류 상태에서 다양한 레이놀즈수에 대해서 속도 및 난동도를 입자영상속도계를 이용하여 측정하였다. 경계층 박리로 인한 재순환 부분이 끝나는 재부착점은 동맥류 최대 확장부 후부에서 발생하였으며, 이 위치는 레이놀즈수의 변화에 따라 바뀌었다. 축방향 속도의 난동은 최대 확장부 후부에서 크게 나타났으며, 이 위치에서 난동에 의한 부가적 응력이 크며 혈관벽 구조변화가 발생하리라 예측된다. 동맥류 내부의 압력분포는 수치해석에 의해 계산되었다. 동맥류 내부 압력은 크기가 증가함에 따라 커졌으며 압력은 동맥류 최대 확장부 후부에서 발생하는 재부착점에서 최대값을 나타내었다. 동맥류 최대확장부 후부는 압력이 최대값을 가지며, 전단력의 변화 및 난동이 큰 지역이므로 동맥류의 파열이 발생하기 쉬운 지역으로 예측된다.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.729-733
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• 2010

Endovascular treatment of the aortic aneurysm with a stent graft is rapidly evolving. We describe here a case of hybrid TEVAR (thoracic endovascular aortic repair) in which the stent grafts were placed in the aortic arch after debranching of the arch vessels. The patient had undergone ascending aorta replacement for acute type I aortic dissection 2.5 years earlier. The aneurysmal change of the distal dissection progressed with time. A provisional bypass surgery from the ascending aorta to the innominate artery and left carotid artery was performed and then stent grafts were inserted via an antegrade route that covered the whole aortic arch and proximal descending thoracic aorta.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.95-105
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• 2018

Increasing cruise speed is an important issue for the development of the next generation rotorcraft. Among several concepts proposed by previous research, the rotorcraft with ducted fan demonstrates its possibility of high-speed flight. In this study, numerical simulations are conducted to investigate the aerodynamic and flow characteristics of multi-ducted fan in forward flight. The aerodynamic efficiency around front ducted fan is determined by interaction between free-stream velocity and the induced velocity. While flow characteristics of rear ducted fan are dominantly influenced by the front ducted fan. Separation in the front ducted fan occurs faster than that of rear ducted fan, and the separation at duct inlet induces an increase of fan thrust. As a result of interaction effect between each ducted fan, relatively aligned inflow enters to the rear ducted fan. Therefore, thrust of the rear fan is decreased steadily before separation, and sudden changes of thrust in fans occur simultaneously. Due to the pressure decrease on lower surface, the normal force of rotorcraft is reduced with forward speed.

• Journal of Chest Surgery
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• v.30 no.7
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• pp.719-723
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• 1997

We experienced a case of aneurysm of the sinus of Valsalva dissecting into the ventricular dseptum. This dissection was induced by paravalvular leakage after aortic and mitral valve replacement. This 37-year-old male was admitted via emergence room due to progressive dyspnea. He had undergone aortic valve replacement(carbomed c" 23 mm) and mitral valve replacement(carbomedic 31 mm) due to aortic regurgitation and mitral regurgitation about 6 years prior to admission and followed up regularly. The diagnosis was made by transthoracic and transesophageal echocardiography and reconfirmed by root aortography. The inlet of the ventricular septal aneurysmal sac was repaired by one layer suture with 3-0 prolene of the endocardium, epicardium and homograft muscle shoulder altogether. Postoperative course was uneventful and the patient was discharged on the 11th postoperative day. day.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.121-124
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• 2012

비정상 유동 해석을 수행하는데 있어서 비정상 Navier-Stokes 방정식을 적용한 결과와 정상 N-S 지배 방정식을 적용한 결과의 차이를 비교하려한다. 적용하고자 하는 비정상 유동은 대칭형 에어포일 NACA0012 에어포일 주위 유동으로 정하였으며, 이 때 에어포일 시위(chord) 길이와 자유류(free stream) 속도 기준으로 Re=100,000에 해당한다. 계산결과 비정상 지배 방정식을 적용한 경우 비정상 유동박리(flow separation)를 모사 할 수 있었으며, 평균 양력계수($C_L$)와 항력계수($C_D$)는 실험치와 비교적 잘 일치하였다. 하지만 정상 N-S 방정식을 적용했을 경우 비정상 유동을 모사하기 어려웠으며 평균양력, 항력계수도 실험치와 차이를 보였다. 이러한 결과는 비정상 유동 해석시 시간에 따라 변화하는 유동의 특성을 고려해 비정상 N-S 지배 방정식을 적용해야한다는 사실을 보이고 있다.

• Journal of Chest Surgery
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• v.31 no.1
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• pp.66-68
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• 1998

A 27-year-old male presented with an anterior myocardial infarction following blunt chest trauma sustained in motorcycle accident. On examination, there was no visible wound on the chest wall. Echocardiogram showed dyskinesia over anterior left ventricular wall. Subsequent coronary angiogram demonstrated dissection at the proximal portion of the left anterior descending coronary artery and left ventriculogram showed apical anerysm and thrombus. He was treated by coronary artery bypass graft.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.522-523
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• 2000

우리나라에서 건강식품으로 널리 알려져 있는 참전복은 불로장수의 식품으로 널리 애용되고 있을 뿐만 아니라 발암억제 물질인 paolin을 함유하고 있어, 세계적으로 상품가치가 인정되고 있다. 이러한 중요성에도 불구하고 참전복 부착치패의 성장 및 생존율 제고는 아직까지도 해결되어야 할 문제로 남아 있는 실정이다. 참전복 부착치패의 먹이선택성 및 유인성에 관한 기존의 연구를 보면 Viana et al. (1994)은 평균 각장 4.2 cm인 치패를 이용하여 배합사료의 9가지 원료에 대한 유연성을, Harada and Kawasaki (1982)는 각장 2.4 cm 이상인 치패를 대상으로 해조류 3종(미역, 톳, 파래)의 유인효과에 관하여 보고하였다. 그러나 이와 같은 보고들은 전복 종묘생산 현장에서 보다 빠른 시기에 박리하여 해조로 먹이 전환을 하기 위한 노력과는 어느 정도의 거리가 있다고 판단된다. 따라서 본 연구에 있어서는 평균 각장 5.0$\pm$1.0 mm인 치패를 박리하여 Navicula spp., 해조 2종(다시마, 파래) 및 자체 제조한 사료를 공급하여 먹이별 유인효과를 관찰하였다. (중략)

• Journal of Chest Surgery
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• v.30 no.3
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• pp.300-307
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• 1997

We have experienced 25 cases of aortic aneurysm from October 1987 to January 1996. Patients ranged in age from 26yrs to 73yrs(mean age 52. Syrs). There were 13 males and 12 females. Eighteen cases were thoracic aneurysm and seven were abdom nal aneurysm. The cause of aneurysm were dissecting in 16cases aneurysms and non-dissecting in 9 cases. Risk factors of aortic aneurysm were hypertension, hypercholesterolemia, Marfan's syndrome. In thoracic aneurysm patients, 1'S cases of dissecting aneurysm underwent aneurysmectomy and replacement of vessel interposition graft with or without coronary artery implantation on the graft. 6 cases of non-dissecting aneurysm underwent operation with same policy as dissecting aneurysm. In 7 case of abdominal aneurysm,all patients underwent aneurysmectomy and graft interposition with straight i)r Y graft. Thcre were 5 postoperative death(mortality 20%). Several cases of complications were improved with proper managements. All survivors showed improvement in clinical symptom and sign and discharged without specific complications.

• Journal of Conservation Science
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• v.11 no.1 s.14
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• pp.1-14
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• 2002

After the construction (1398 year at first, secondarily reconstructed at 1448 year), the Soongryemoon (South Gate) had been preserved to late 19c without large damages. The present shape of the gate have been kept after the repairments of two times (1953, 1963). However, the rocks constituting the walls of the gate have been strongly weathered, exfoliated and cracked due to severe changes in the environment as traffic increase, air pollution and the subway which may seem also to cause the structural unstability. The rocks composed of the walls of the gate are almost of granites. On the rocks such deteriorations as onion structure, surface exfoliation, cracks, and edge breakout are developed. These deteriorations may be caused genetically by strong weathering, differential load due to possibly structural unstability, impact and unknown reasons. For the establishment of conservation plan, the factors of these deterioration phenomena and structural unstability must be quantitatively analyzed and diagnosed in detail.

• Journal of Korean Neurosurgical Society
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• v.29 no.12
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• pp.1668-1672
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• 2000

Nontraumatic, incracranial giant aneurysm has rarely been reported as the cause of the spontaneous subarachnoid hemorrhage in childhood. Multiple, dissecting giant aneurysms on the left middle cerebral artery with sudden onset of headache in a 14-year-old girl were successfully clipped and followed by complete relief of symptoms. The rarity and characteristics of such lesion in childhood and its successful surgical treatment are discussed briefly.