• Journal of Yeungnam Medical Science
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• 제21권2호
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• pp.143-150
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• 2004

A thromboembolic stroke is believed to be precipitated by a rupture of vulnerable atheromatous plaques. Until recently the assessment of a further risk of stroke in high-risk patients in whom atherosclerosis has presented with a transient ischaemic attack (TIA), has been confined to a quantitative assessment of the luminal patency of the internal carotid artery. These traditional stratification parameters are no longer believed to be the most accurate predictors of a thrombo-embolism. This is because the process of vessel wall remodeling can maintain a luminal patency, and consequently, quite large friable plaques may remain unidentified. Accordingly, there is a need for an improved risk assessment. The fibrous cap of a vulnerable plaque is thinner, and an intraplaque hemorrhage and inflammation can occur during the development of atherosclerotic plaque. Several imaging methods for identifying vulnerable plaques have been developed. Recently, high resolution magnetic resonance (MR) imaging has emerged as an accurate non-invasive tool that can characterize the carotid plaque components in vivo. A High resolution carotid magnetic resonance is capable of distinguishing an intact, thick fibrous cap from a thin and ruptured cap in carotid plaque. In addition, a plaque MR can identify the active inflammation and detect a hemorrhage. High resolution carotid MR imaging is a valuable noninvasive method for quantifying the plaque components and identifying vulnerable plaque.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.161-168
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• 2011

Cerebral aneurysm mostly occurs at a bifurcation of the circle of Willis. When the cerebral aneurysm is ruptured a disease like subarachnoid hemorrhage and stroke is caused and this can be even deadly for patients. Generally it is known that causes of the intracranial aneurysm are a congenital deformity of the artery and pressure or shear stress from the blood flow. A blood flow pattern and the geometry of the blood vessel are important factors for the aneurysm formation. Research for several hemodynamic indices has been performed and these indices can be used for the prediction of aneurysm initiation and rupture. Therefore, the numerical analysis was performed for hemodynamic characteristics of the blood flow through the cerebral artery applying the various bifurcation angle and flow rate ratio. We analyze the flow characteristics using indices from the results of the numerical simulation. In addition, to investigate the flow pattern in the aneurysm according to the bifurcation angle and the flow rate ratio, we performed the numerical simulation on the supposition that the aneurysm occurs.

• Journal of Advanced Marine Engineering and Technology
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• 제21권4호
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• pp.372-380
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• 1997

This paper describes experimental investigations of helium-air exchange flows through parti¬tioned opening and two-opening. Such exchange flows may occur following rupture accident of stand pipe in high temperature gas cooled reactor. A test vessel with the two types of small open¬ing on top of test cylinder is used for experiments. An estimation method of mass increment is developed and applied to measure the exchange flow rate. A technique of flow visualization by Mach-Zehnder interferometer is provided to recognize the exchange flows. In the case of exchange flow through the partitioned opening, flow passages of upward flow of the helium and downward flow of the air within the opening are separated by vertical partition, and the two flows interact out of entrance and exit of the opening. Therefore, an experiment of the exchange flow through two-opening is made to investigate effect of the fluids interaction of the partitioned opening sys¬tem. As a result of comparison of the exchange flow rates between the two types of the opening system, it is found that the exchange flow rate of the two-opening system is larger than that of the partitioned opening system due to absence of the effect of fluids interaction. Finally, the fluids interaction between the upward and downward flows through the partitioned opening is found to be an important factor on the helium-air exchange flow.

• 동력기계공학회지
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• 제6권2호
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• pp.40-47
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• 2002

In this paper, friction welding optimization for 1Cr0.5Mo-STS304 (${\phi}14\;mm$), AE applications for the weld quality evaluation and the applications of various life prediction methods such as LMP (Larson-Miller Parameter) and ISM (initial strain method) were investigated : The creep behaviors of those steels and the friction welded joints under static load were examined by ISM combined with LMP at 400, 500, 550 and $600^{\circ}C$, and the relationship between these two kinds of phenomena was studied. The real-time predicting equations of elevated-temperature creep life (rupture time) under any creep stress at any elevated-temperature could be developed by LMP and LMP-ISM. It was confirmed that the life prediction equations by LMP and LMP-ISM are effective only up to 102 h and can not be used for long times of 103-106 h, but by ISM it can be used for long times creep prediction of more than 104 h with most reliability.

• Steel and Composite Structures
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• 제32권6호
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• pp.701-715
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• 2019

Using first-order shear deformation theory (FSDT), a semi-analytical solution is employed to analyze creep damage and remaining life assessment of 304L austenitic stainless steel thick (304L ASS) cylindrical pressure vessels with variable thickness subjected to the temperature gradient and internal non-uniform pressure. Damages are obtained in thick cylinder using Robinson's linear life fraction damage rule, and time to rupture and remaining life assessment is determined by Larson-Miller Parameter (LMP). The thermo-elastic creep response of the material is described by Norton's law. The novelty of the present work is that it seeks to investigate creep damage and life assessment of the vessels with variable thickness made of 304L ASS using LMP based on first-order shear deformation theory. A numerical solution using finite element method (FEM) is also presented and good agreement is found. It is shown that temperature gradient and non-uniform pressure have significant influences on the creep damages and remaining life of the vessel.

• 한국화재소방학회논문지
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• 제15권1호
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• pp.16-22
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• 2001

석유화학플랜트에서 다량 부산되는 가연성 고체인 PP(Polypropylene) 및 LLDPE(Linear low density polyethylene)의 열적특성과 압력용기를 이용하여 산화제와의 혼촉위험성을 조사하였다. 시차주사열량계 및 열중량 분석기를 이용하여 온도에 따른 발열개시온도 및 중량감소를 조사하였고, PP 및 LLDPE의 혼촉위험성을 살펴보고자 소방법상 제1류 위험물로 분류되고 있는 몇 가지 대표적인 산화성 고체와 혼합하여 무게비에 따른 압력용기 내에서의 혼촉위험성을 조사하였다. 또한 가스농도 측정기를 이용하여 PP 및 LLDPE에 대한 연소생성물의 농도를 측정하였다. DSC분석 결과 열분해에 따른 발열 피크가 PP의 경우 220~$250^{\circ}c$ 부근에서 나타나고 있으며, TGA분석결과 PP 및 LLDPE의 분해온도는 각각 200~$350^{\circ}c$, 300~$500^{\circ}c$ 범위이다. 압력용기 시험에 의한 산화제와 PP 및 LLDPE 분진의 혼촉위험성은 오리피스 직경이 감소할수록, 산화제와의 혼촉 무게비가 증가할수록 그리고 시료의 분해온도와 산화제의 분해온도가 비슷한 경우 흔촉위험성이 크게 나타났다. 또한 시료의 연소가스 분석결과 PP의 경우 LLDPE보다 상당히 많은 양의 일 산화탄소가 발생하는 반면 LLDPE가 PP보다 더 많은 양의 이산화탄소 가스를 발생하였다.

• Tuberculosis and Respiratory Diseases
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• 제60권3호
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• pp.347-352
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• 2006

저자들은 1개월간 지속된 왼쪽 어깨통증 및 갑자기 발생한 호흡곤란으로 내원한 36세 여자 환자에서, 편측성 종격동의 종괴와 흉막강으로 파열되어 반대측의 흉수를 동반한 기형종의 진단 및 치료 1예를 경험하여 문헌고찰과 함께 보고하는 바이다.

• Journal of Chest Surgery
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• 제10권2호
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• pp.327-336
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• 1977

A chinical analysis was performed on 383 ases of hest injurjes eperienced at Department of thoraci Surgery, Seoul National University Hospital during 21 year period From 1957 to 1977. Of 383 patients o hest injuries, 209 cases were result from nonpenetrating injuries whereas 175 were from penetrating injuries, and there were 258 cases of hemothorax or/and pneumothorax, 162 of rib fracture, 33 of foreign body, 26 of clavicle frcture, 26 of lung contusion, 17 of diaphragmati laceration, 14 of hemoperiardium, 14 of flail chest and others. Stab wound was the most common in penetrating injuries and followed by gunshot and shell fragments. The majority of nonpenetrating chest injury paiens were traffi accident vitims and falls accounted for the next largest group of accidents. Chest injuries were frequently encountered in the age group between 16 and 50 years, and 321 patients were male comparing to 62 of female. In blunt hest injuries the patients with five or more rib fractures had a 85 per ent incidence of intrathoracic injury and 19 per cent had an intraabdominal organ damage, whereas those with four or less rib fractures had a 69 per cent and a 6 per cent incidence respectively. The principal associated injuries were cerebral contusion on 19 cases, renal contusion on 10, liver laceration on 7, peripheral vessel laceration on 5, spleen laceration on 3 and extremity fracture on 18 patients. The principles of therapy for early complications of chest trauma were rapid reexpansion of the lungs by thoracentesis (46 cases) and closed thoracotomy (125 cases) but open thoracotomy had to be done on 90 cases (23.5%) because of massive bleeding or intrapleural hematoma, foreign body, cardiac injury, diaphragmatic laceration and bronhial rupture. The over all mortality was 2.87 per cent (11 among 383 cases), 8 cases were from penetrating injuries and 3 from nonpenetrating injuries.

• Journal of Chest Surgery
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• 제10권2호
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• pp.337-342
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• 1977

A clinical analysis was performed on 383 cases of chest injurjes experienced at Department of Thoracic Surgery, Seoul National University Hospital during 21 year period from 1957 to 1977. Of 383 patients of chest injuries, 209 cases were result from nonpenetrating injuries whereas 175 were from penetrating injuries, and there were 258 cases of hemothorax or/and pneumothorax, 162 of rib fracture, 33 of foreign body, 26 of clavicle fracture, 26 of lung contusion, 17 of diaphragmatic laceration, 14 of hemopericardium, 14 of flail chest and others. Stab wound was the most common in penetrating injuries and followed by gunshot and shell fragments. The majority of nonpenetrating chest injury patients were traffic accident victims. and fails accounted for the next largest group of accidents. Chest injuries were frequently encountered in the age group between 16 and 50 years, and 321 patients were male comparing to 62 of female. In blunt chest injuries the patients with five or more rib fractures had a 85 per cent incidence-of intrathoracic injury and 19 per cent had an intraabdominal organ damage, whereas those with four or less rib fractures had a 69 per cent and a 6 per cent incidence respectively. The principal associated injuries were cerebral contusion on 19 cases, renal contusion on 10, liver laceration on 7, peripheral vessel laceration on 5, spleen laceration on 3 and extremity fracture on 18 patients. The principles of therapy for early complications of chest trauma were rapid reexpansion of the lungs by thoracentesis [46 cases] and closed thoracotomy [125 cases] but open thoracotomy .had to be done on 90 cases [23-5%] because of massive bleeding or intrapleural hematoma, foreign body, cardiac injury, diaphragmatic laceration and bronchial rupture. The over all mortality was 2.87 per cent [11 among 383 cases], 8 cases were from penetrating injuries and 3 from nonpenetrating injuries.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.797-805
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• 2003

This paper describes experimental investigations of helium-air exchange flow through single opening and partitioned opening. Such exchange flows may occur following rupture accident of stand pipe in high temperature gas cooled reactor. A test vessel with a small opening on top of test cylinder is used for experiments. An estimation method of mass increment is developed and applied to measure the exchange flow rate. A technique of flow visualization by Mach-Zehnder interferometer is provided to recognize the exchange flows. Flow measurements are made with the opening, for partition ratios H_p/H$_1$$ in the range 0 to 1. where H_p$ and H$_1$ are partition length and height of the opening. respectively. In the case of H_p/H$_1$$ of 0, flow passages of upward flow of the helium and downward flow of the air within the opening are unseparated (bidirectional), and the two flows interfere within the opening. The unseparated flow increases strength of flow resistance and therefore, the exchange flow rate is minimum through range of the partition ratios. Two flow zones, i.e., separated (unidirectional) flow zone and unseparated (bidirectional) flow zone, exist with increasing the partition length. The exchange flow rate increases with increasing the separated flow zone. It is found that a maximum exchange flow rate exists at H_p/H$_1$$ of 1. As a result of comparison of the exchange flow rates by changing the partition ratio, the fluids Interference in the unseparated zone is found to be an important factor on the helium-air exchange flow rate.