• 정보과학회 논문지
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• 제43권4호
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• pp.419-429
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• 2016

최근 관상동맥 영역화 결과로부터 삼차원 표면 모델을 생성함으로써 혈관 구조적 정보의 렌더링 효율성의 증대뿐만 아니라 전산유체역학를 이용한 혈류 역학 시뮬레이션을 통해 혈류분획예비력과 같은 생리적 정보들을 획득하는 연구들이 활발히 진행되고 있다. 본 논문에서는 혈관 영역화 과정에서 획득한 혈관 구조 정보를 입력 데이터로 사용하여 관상동맥의 삼차원 삼각 표면 메쉬 모델을 생성하는 방법을 제안한다. 관상동맥 영역화 결과로부터 삼각형 표면 메쉬 모델을 만드는 방법으로는 Marching cube 알고리즘에 기반한 방법들이 있지만 이산적인 영상 공간에서 수행되는 알고리즘으로 가늘고 다양한 굴곡을 갖는 혈관 경계를 표현하기 힘들다. 제안된 방법은 관상동맥 영역화 과정에서 추정한 혈관 중심좌표와 법선 벡터 그리고 직경 정보를 이용하여 기존 방법들보다 정교하게 단일 혈관 가닥들에 대한 삼각 표면 메쉬들을 생성하고 분기가 일어나 중첩되는 메쉬들은 메쉬 병합 기법을 사용하여 처리함으로써 통합된 관상동맥 메쉬를 생성한다.

• 대한소아치과학회지
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• 제27권4호
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• pp.485-489
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• 2000

점액종은 점액소를 함유한 낭종으로서, 인접 조직으로 선분비물이 유출되거나 소타액선관이 폐쇄되어서 형성된다. 다른 질환과의 감별진단 후 완전히 낭종을 제거해야만 완전 치유가 이루어지며, 절개 배농이나 흡입은 단지 일시적인 방법일 뿐 반드시 재발한다. $CO_2$ Laser를 이용한 구강영역에서의 치료 시 장점으로는 우수한 지혈효과, 우수한 시야확보, 인접조직 손상의 최소화 뿐만 아니라, 작은 혈관과 림프관을 봉쇄하는 능력이 있어 창상치유시 나타나는 염증과정의 초기 증상들을 차단하기 때문에 술후 감염 감소, 술 후 종창 및 동통 감소 등이 나타나며, 반흔조직 및 창상수축의 감소 등이 있다.

• Advances in pediatric surgery
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• 제8권2호
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• pp.101-106
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• 2002

The antiangiogenic effects of novel agent KJ3, Betulinic acid, and Fumagillin on the neovascularization were studied by examining ultrastructural alterations in the vasculature of synthetic gelform and mouse neuroblastoma C1300. Small pieces of gelform with 0.4% agar were introduced subcutaneously (s.c.) in 7 week old male CH3/HeJ mice. After the $LD_{50}s$ were determined by FACS analysis, a third of $LD_{50}$ of three drugs were injected either locally or intraperitoneally every other day for 14 days. A/J mice were inoculated s.c. with the C1300 neuroblastoma cell line, then either saline or three drugs were injected in the same manner. The antiangiogenic effects of three drugs were studied by measuring the histologic changes in tumors, and immunostaining for CD34, VIII/vWF, CD105, and thymidine phosphorylase. In the drug treated groups, the number of vessels in gelform experiments and C1300 neuroblastoma experiments were lower than the corresponding values in the control. The histologic findings were significantly different in drug treated groups on day 7, but these were not significant on day 14. These results imply that antiangiogenic agents were effective when the tumor burden is minimal.

• Advances in pediatric surgery
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• 제16권2호
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• pp.101-107
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• 2010

Herniorrhaphy of Indirect inguinal hernia (IIH) is one of the most frequently performed surgical procedures in children. The overall incidence of inguinal hernias in childhood ranges from 0.8 to 4.4 %. The incidence is up to 10 times higher in boys than girls, especially much higher in premature infants. IIHs in children are basically an arrest of embryologic development rather than an acquired weakness, which explains the increased incidence in premature infants. In normal development, the processus vaginalis closes, obliterating the peritoneal opening of the internal ring between 36th and 40th week of gestation. This process is often incomplete, leaving a small patent processus in many newborns. However, closure continues postnatally, and the rate of patency is inversely proportional to age of the child. The presence of a patent processus vaginalis is a necessary but not sufficient variable in developing a congenital IIH. In other words, all congenital IIHs are preceded by a patent processus vaginalis, but not all patent processus vaginalis go on to become IIHs. The overall incidence of IIH in population is approximately 1 to 2 % and the incidence of a processus vaginalis is approximately 12 to 14%, clinically appreciable IIH should develop in approximately 8 to 12 % of patients with a patent processus vaginalis. Although the classic open inguinal hernia repair remains the gold standard for most pediatric surgeons, laparoscopic repair is being performed in many centers. Like open technique, laparoscopic technique is fundamentally a high ligation of the indirect hernia sac with or without internal ring ligation. The advantages of laparoscopic approach include the ease of examining the contralateral internal ring, the avoidance of access damage to vas and vessels during mobilization of cord, decreased operative time, and an ability to identify unsuspected direct or femoral hernias. Almost all groin hernias in children are IIHs and occur as a result of incomplete closure of processus vaginalis. The treatment is repair by high ligation of hernia sac, which can be done by an open or laparoscopic technique. The contralateral side can be explored by laparoscopy or left alone, open exploration is no longer indicated due to potential risk of infertility.

• Tuberculosis and Respiratory Diseases
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• 제41권6호
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• pp.658-662
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• 1994

저자등은 종격동에서 늑막삼출액과 함께 종물이 있는 소견을 보였던 환자에서 세포진검사 및 면역화학적 검사를 통하여 평활근육종으로 진단된 1예를 경험하였기에 문헌고찰과 함께 이를 보고하는 바이다.

• 한국항해학회지
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• 제10권2호
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• pp.97-114
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• 1986

Ship's maneuverability is very important factor in safe ship handling and economical ship operation. Steering characteristics are consisted of course stability and maneuverability. Today in many advanced ship-building countries, they study ship's course stability, using model ship tests, such as straight line tests, rotating arm tests and Planar Motion Mechanism (PMM) etc., in tow in tanks. It is the purpose of this paper to provide ship's handlers with better understanding of steering characteristics and to help them in safe controlling and manevering . In this paper, the author simulated response of various vessels, running straight course with constant speed, and they are disturbed by small external disturbance of one degree yaw angle with no angular velocity . The author used the hydrodynamic derivtives resulted at tests of Davidson's laboratory in Stevens Institute of Technology, New Jersey, U.S.A. Course stability was evaluated and analyzed in various respects, such as block coefficient, ratio of ship's length to beam, draft and rudder area ratio etc. The obtained results are as follows : (1) The ship's course stability is affected by magnitude of block coefficient greatly. In case that the block coefficient is more than 0.7, the deviation varies at nearly same rate but the requistite time to reach the steady course is different. (2) The ship's course stability is affected by magnitude of L/B. When the dimensionless time reaches about 3, the deviation and requisite time to reach the steady course are influenced nearly same. After the dimensionless time is about 3, they change on invariable ratio. (3) The effect to course stability by L/T and RA' can be neglected. (4) The reason why thy VLCC and container feeder vessel are unstable on their course is that their block coefficient is generally more than 0.8 and the ratio of ship's length to beam is about 6.0.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 공동학술발표회
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• pp.129-130
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• 2017

본 연구에서는 쌍동형 카페리에 대한 기본 구조 설계 및 구조 해석을 위한 기법을 제시한다. 카페리와 같이 길이 50미터 이상 길이와 폭/비가 12보다 큰 중/소형 고속 선박의 강도 해석에 대한 규정이나 방법론은 아직까지 명확하게 제시되지 않고 있다. 따라서 본 논문에서 부재의 스캔틀링은 한국선급기준을 적용하였고, 설계안에 대한 구조강도 검증을 위해서 카페리 전용선박 기준에 의해 추가적으로 검증하였다. 특히, 카페리 전용선박 기준을 적용하여, Hull girder ultimate strength를 추가적으로 수행하여, 현재 기준에 의한 설계의 모호성을 극복하도록 제안하였다. 본 연구를 통해 도출된 연구 결과는 앞으로 고속 쌍동형 카페리의 구조설계 및 구조해석에 관련된 기본적인 자료로 유용하게 활용될 것으로 예상된다.

• Smart Structures and Systems
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• 제26권3호
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• pp.331-343
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• 2020

In this paper, based on the CPT, motion equations for a sandwich plate containing a core and two integrated face-sheets have derived. The structure rests on the Visco-Pasternak foundation, which includes normal and shear modules. The piezo-magnetic core is made of CoFe₂O₄ and also is subjected to 3D magnetic potential. Two face sheets at top and bottom of the core are under electrical fields. Also, in order to obtain more accuracy, the effect of flexoelectricity has took into account at face sheets' relations in this work. Flexoelectricity is a property of all insulators whereby they polarize when subject to an inhomogeneous deformation. This property plays a crucial role in small-scale rather than macro scale. Employing CPT, Hamilton's principle, flexoelectricity considerations, the governing equations are derived and then solved analytically. By present work a detailed numerical study is obtained based on Piezoelectricity, Flexoelectricity and modified couple stress theories to indicate the significant effect of length scale parameter, shear correction factor, aspect and thickness ratios and boundary conditions on natural frequency of sandwich plates. Also, the figures show that there is an excellent agreement between present study and previous researches. These finding can be used for automotive industries, aircrafts, marine vessels and building industries.

• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.441-445
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• 2000

Considering international status of our country as world class ship builder and geographical characteristics encircled by sea in three facets, controlling of air pollutants emission from marine engines becomes more and more important issue in recent days. Implementation of immediate pollutants emission control regulation and standardization of test and certification procedure are required to reduce air pollution from marine engines. But cost increments due to additional equipment of emission control device and development and certification test expenses as well as depreciation of fuel economy should be considered. To satisfy those air pollution reduction and economic requirements, we should make our own interpretation of IMO standard and implementation schedule depending on our country's status. For this purpose we measured NOx emission from small and middle class marine engines to calculate emission factor and total pollutant emission in our country. With the comparison and analysis of other countries emission control regulation we proposed basic data of total emission from marine engine and future emission control standard in our country. According to our estimation, 62% of total NOx emission of marine engines comes from fishing boat and 38% from commercial vessels. The portion of NOx emission from marine engine is 18.6% of whole country NOx emission. Due to the voyage characteristics of middle and large vessel and necessity of international harmonization of marine engine pollutants emission control standard, it is inevitable to adopt IMO standard for middle and large marine engines. But considering technological and cost effect of fishing boat operating in near sea, it is resonable to set a standard within 80% of measured value at the moment and gradually implement the same IMO standard in near future.

• Macromolecular Research
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• 제8권4호
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• pp.179-185
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• 2000

Generally vascular grafts with a relatively large inner diameter (> 5 mm) have been successfully employed for replacement in the human body. However, the use of small diameter grafts is limited, because these grafts rapidly occlude due to the thrombosis. The ideal blood-contacting surface of a prosthesis would be an endothelial cell (EC) lining, because the confluent monolayer of healthy ECs that culture natural blood vessels represents the ideal nonthrombogenic surface. For vascular graft application, the stable EC adhesion on surface under How conditions is very important. In this study, the adhesive strength of ECs attached on polymer surfaces coated with collagen type IV (Col IV), fibronectin (Fn), laminin (Ln), and treated with corona was investigated onto polyurethane (PU) films. The EC-attached PU surfaces were mounted on parallel-plate flow chambers in a How system prepared for cell adhesiveness test. Three different shear stresses (100, 150, and 200 dyne/㎠) were applied to the How chambers and each shear stress was maintained for 120 min to investigate the effect of shear stress and surface treatment condition on the EC adhesion strength. It was observed that the EC adhesion strength on the surface-modified PU films was in the order of Ln≡Fn > Col IV > corona 》 control. More than 70% of the adhered cells were remained on surface-modified PU surface after applying the shear stress,200 dyne/㎠ for 2 hrs, whereas the cells were completely detached on the control PU surface within 10 min after applying the same shear stress. It seems that the type of adsorbed proteins and hydrophilicitv onto the PU surfaces play very important roles for cell adhesion strength.