• Journal of applied mathematics & informatics
• /
• 제10권1_2호
• /
• pp.193-207
• /
• 2002

The present investigation deals with the pulsatile flow of incompressible viscous fluid through a circular rigid tube provided with constriction. The method applied here is the Decomposition Method, which has been developed by George Adomian [3]. The advantages of this method are the avoidance of simplifications and restrictions, which change the non-linear problem to mathematically tractable one, whose solution is not consistent with physical solution. Theoretically results, such as, wall shear stress and axial velocity component, have been obtained and the graphical solutions of these theoretical results have been shown in the figures.

• Tribology and Lubricants
• /
• 제12권4호
• /
• pp.52-59
• /
• 1996

The results of the electrical contact conductivity of multi-contact spots accounting the surface roughness and the non-conductive films of different origins such as air, water, cutting oil, and machining oil are presented. The array of metal spheres compressed between two flat plates has been used for simulation of the contact behavior of multiple contact of solids, under normal loading. Measurement of electrical contact resistance has been made using the equipment providing the adequate accuracy in the range of micro Ohms. The data on electrical contact resistance have been compared with theoretical predictions using the multiple contact model of constriction resistance. The effect of single spot number and array on conductivity of contact has been evaluated. The results of the experiments show that the contact resistance are closely related to the number of loading cycles, form of surface roughness, and presence of non-conductive films that reduce the size of the real electrical contact spots.

• Journal of Chest Surgery
• /
• 제24권2호
• /
• pp.202-205
• /
• 1991

Development of an aneurysm in the thoracic aorta, intercostal arteries, or cerebral vessels is not an uncommon occurrence in patients with coarctation of the aorta. The mechanism whereby coarctation predisposes to aneurysm formation is incompletely understood and we suggest that in this case, an intrinsic factor in the wall of the aorta underlies the formation of aneurysms. Recently we experienced one case of COA associated with the thoracic aortic aneurysm and operation was done successfully. PDA was simply ligated and the aorta was cross-clamped proximally and distally and the area of constriction or aneurysmal site were excised. Postoperative course was uneventful and the patient was discharged 2 weeks after operation. Hypertension at upper extremities was controlled without any antihypertensive drugs after operation and the degree of regurgitation of mitral valve was improved postoperatively but long-term follow-up should be necessary.

• 한국산업안전학회:학술대회논문집
• /
• 한국안전학회 1998년도 춘계 학술논문발표회 논문집
• /
• pp.265-270
• /
• 1998

As the goal of enterprises is to pursuit benefits, the goal of safety management is not only preventing accidents but also promoting benefits and productivity. However, enterprises have failed to realize the necessity of safety management, partly because they didn't grasp any appropriate evidences advocating effectiveness of safety management. This study aimed to survey construction-site engineers' consciousness on safety management contributing to cost reduction, construction period and quality enhancement. The result of this study showed that constriction-site engineers recognized the ratio of direct cost to Indirect cost as 1:2. The proportion of repliers who thought that safety management is contributable to cost reduction was 35％, to construction period was 20％, and to quality enhancement was 48％. The construction sites with excellent safety accomplisments also had good work and selling amounts.

• 한국응용약물학회:학술대회논문집
• /
• 한국응용약물학회 1996년도 춘계학술대회
• /
• pp.191-191
• /
• 1996

BQ-123, a selective $ET_{A}$ receptor antagonist, reverses various responses induced by Endothelin-1 and it has been reported that BQ-123 ameliorates the cerebrovascular constriction, hypertension, and decrease of blood flow. Previously, we announced that the level of Endothelin-2 increase in the brain and spinal cord of EAE-induced lewis rat and showed the origin of ET-1 is activated macrophages. Intracisternal injection of $ET_{A}$ receptor antagonist, BQ-123(10nmol) was done for visualizing the role of endothelin-1 on the pathogenesis of EAE. BQ-123 apparently blocked the severity of clinical score of EAE and decreased the histologically observed inflammatory region. The blocking effect on the progression of EAE model following BQ-123, suggests that BQ-123 is a physiological antagonist in terms of development of the sign of multiple sclerosis.

• 대한음성학회지:말소리
• /
• 제57호
• /
• pp.43-58
• /
• 2006

This study aims to investigate whether Chinese learning Korean and Korean native speakers show any difference in length and formant structures of the Korean liquid 'ㄹ' in the environments of v_v and v_# through the acoustic analysis of 10 Chinese learners' and 10 Koreans' utterances. The acoustic analysis of L2KSC DB shows that the length and formant structures of 'ㄹ' produced by Chinese learners are significantly different from the ones by Koreans. I explain these differences by contrasting the liquids and syllable structure constraints of the two languages, Chinese and Korean. In addition, I relate the F1 and F2's values to the tongue's movement when making a constriction, and conclude that Chinese learners pronounce the 'ㄹ' in the v_# environment with the tongue lower and backer than Koreans do.

• 한국전산유체공학회지
• /
• 제9권3호
• /
• pp.66-72
• /
• 2004

전도 열전달 분야에서 두 물체가 접해 있는 경우, 접촉 열저항은 고려해야 할 중요한 요소이다. 특히 최근에는 전자부품의 과열방지를 위한 열 소산과 관련하여 접촉 열저항 문제는 중요하게 대두되고 있으며 이에 관련한 많은 이론적 연구와 응용연구가 수행되고 있다. 접촉 열저항은 주로 거친 두 물체표면의 불완전접촉에 기인한다. 본 연구에서는, 접촉하는 두 물체사이의 접촉면을 이상화시킨 비교적 간단한 문제를 이론적으로 해석함으로써 접촉면의 틈새 형상 및 비접촉면적비(비접촉면적/외관접촉면적)의 크기에 따른 접촉 열저항의 크기를 구하였다.

• Journal of Chest Surgery
• /
• 제17권3호
• /
• pp.448-455
• /
• 1984

Coarctation of the Aorta is a congenital constriction of aorta of varying degree, usually located at or near the aortic ismuth with frequent associations of other cardiac anomalies. Various modes of surgical corrections, such as resection and end-to-end anastomosis, graft interposition, angioplasty using prosthetic patch or subclavian flap have been used according to the status of coarctation and age of the patient. We have experienced two cases of surgically treated coarctation of the aorta, one of which was preductal coarctation with hypoplastic aortic arch and ventricular septal defect in a 4 year old boy, and the other case was juxtaductal type with aortic regurgitation. Subclavian flap angioplasty with additional pulmonary artery banding procedure was done in the first case and wedge resection with end-to-end anastomosis and aortic valve replacement [St. Jude valve, 23mm] 20 days later of first operation in the other case. The first case developed massive tarry stool on 3rd POD, probably due to mesenteric arteritis with resultant bowl ecrosis, and expired the next day. Recovery was uneventful with the second case.

• Journal of Chest Surgery
• /
• 제21권3호
• /
• pp.541-546
• /
• 1988

A 34-year-old female was seen with Budd-Chiari syndrome caused by an obstruction of the inferior vena cava above the hepatic veins. Transatrial dilation or membranotomy was not available due to severe hourglass constriction of the inferior vena cava. Retrohepatic cavoatrial bypass with a low porosity woven Dacron graft[24mm in the diameter] was performed. For increasing the patency of venous graft, we used anticoagulation with warfarin. Postoperative course was uneventful except pleural effusion of the right luring.

• 한국수자원학회논문집
• /
• 제30권3호
• /
• pp.201-210
• /
• 1997

$textsc{k}$-$\varepsilon$난류모델을 이용한 개수로 급축소부 흐름의 해석을 위한 수치모형을 개발하였고, 그 수치실험결과는 실험결과와 잘 일치하였다. 이는 난류모델에 의한 적절한 난류 와점성계수의 산정이라 생각된다. 유함수 및 유속분포의 분석을 통한 축소부 통과후 급변화 흐름의 수리특성을 분석하였고, 또한 난류 와점성계수의 분포를 분석하였다. 따라서 천수방정식의 점성항에 경험적인 유효점성계수의 도입보다는 흐름의 양상과 장소에 따라서 변화하는 난류와점성계수의 산정에 의한 급변화흐름의 해석이 필요하다.