• Journal of Korean Neurosurgical Society
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• 제41권6호
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• pp.429-431
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• 2007

Although the ventriculo-peritoneal shunt is the treatment of choice when hydrocephalus should be corrected, the ventriculo-atrial shunt still holds strong alternative when the peritonium is precluded due to the several reasons. During the ventriculo-atrial shunt operation, it is not always easy to dissect and find the corresponding venous structures. In this technical note, the author describes a simple method of percutaneous insertion for placement of the atrial end.

• 한국항해항만학회지
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• 제34권6호
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• pp.417-422
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• 2010

정수중 부선 주위의 유동 특성을 조사 및 분석하기 위하여 부선의 저항성능을 모형시험과 CFD를 이용한 수치계산에 의하여 해석하였다. 모형실험은 무한수심 조건에서의 회류수조에서 저항과 선측파형 등을 관측하였으며, 유동장 해석을 위하여 VOF(Volume of Fluid)법을 기초로 한 수치 시뮬레이션을 이행하였다. 부선의 형태에 따르는 유동특성을 파악하기 위하여 서로 다른 모습의 부선 모형을 제작하였으며, 모형실험은 설계속도를 7kts로 정하고 역조와 순조의 조류 영향을 고려하여 5kts~10kts의 구간에서 실험을 실시하여 각 속도에 따르는 저항 특성을 비교 검토 하였다. 수치 시뮬레이션은 일정 속도에서 만재상태를 기준으로 하여 계산을 수행하였으며 수조 실험 결과와 상호 비교함으로서 본 수치계산법의 타당성을 검증할 수 있었으며, 부선의 저항성능 및 선체 주위 유동장의 특성을 분석하였다. 저속일 때 25% 정도의 저항의 차이가 발생하고, 7kts부터 유효마력이 급격히 증가하는 현상을 파악할 수 있었다.

• Advances in pediatric surgery
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• 제15권1호
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• pp.1-10
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• 2009

최근에 양수에 존재하는 세포들은 다양한 세포분화의 능력을 가지고 있으며 세포 치료와 조직공학의 세포원으로서의 가능성이 높다는 연구 결과가 많이 보고되고 있다. 그러나 양수 내에 어떤 종류의 세포가 정상적으로 존재하는 지에 대해서는 제한적으로 알려져 있다. 본 연구에서는 사람의 양수 내에 호흡기세포를 분리 배양하는 것을 목표로 하였다. 임신 17주에서 20주 사이의 산모 10명에서 각각 5 mL의 양수를 획득하여 small airway growth medium (SAGM) 배양액에서 계대 배양을 시행하였으며 type II alveolar cells이 존재하는 지에 대하여 면역형광염색 및 RT-PCR을 시행하였다. 배양된 세포는 광학현미경 상 상피세포와 유사한 다면체의 모양이었으며 계대 배양 시에 변화 없이 동일한 형체를 보였다. 배양된 세포는 면역형광염색 상 type II alveolar cell의 특이표지자인 surfactant protein C (SPC) 및 TTF-1 protein에 대해서는 양성이었으나 CD 31 및 vimentin에 대해서는 음성이었으며, RT-PCR 상 SPC mRNA 가 발현되었다. 이상의 결과로 사람의 양수를 특이 배양액에 배양하면 호흡기세포를 분리, 확인할 수 있음을 알았으며 이러한 결과가 향후 양수세포의 추가적인 연구에 활용될 수 있다고 생각된다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.151-158
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• 2009

To implement the insects' flapping flight for developing flapping MAVs(micro air vehicles), the unsteady flow characteristics of the insects' forward flight is investigated. In this paper, two-dimensional FSI(Fluid-Structure Interaction) simulations are conducted to examine realistic flow features of insects' flapping flight and to examine the flexibility effects of the insect's wing. The unsteady incompressible Navier-Stokes equations with an artificial compressibility method are implemented as the fluid module while the dynamic finite element equations using a direct integration method are employed as the solid module. In order to exchange physical information to each module, the common refinement method is employed as the data transfer method. Also, a simple and efficient dynamic grid deformation technique based on Delaunay graph mapping is used to deform computational grids. Compared to the earlier researches of two-dimensional rigid wing simulations, key physical phenomena and flow patterns such as vortex pairing and vortex staying can still be observed. For example, lift is mainly generated during downstroke motion by high effective angle of attack caused by translation and lagging motion. A large amount of thrust is generated abruptly at the end of upstroke motion. However, the quantitative aspect of flow field is somewhat different. A flexible wing generates more thrust but less lift than a rigid wing. This is because the net force acting on wing surface is split into two directions due to structural flexibility. As a consequence, thrust and propulsive efficiency was enhanced considerably compared to a rigid wing. From these numerical simulations, it is seen that the wing flexibility yields a significant impact on aerodynamic characteristics.

• Journal of Chest Surgery
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• 제10권2호
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• pp.281-294
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• 1977

Superior vena cava to pulmonary arterial shunting operation was made between the superior vena cava and the right pulmonary artery in the fashion of end-to-end anastomosis in 20 mongrel dogs. The experimental animals were divided into three group and blood flow in the superior vena cava was occluded for 20, 30 and 60 minutes respectively, and observations were made for the changes in caval pressure and cerebrospinal fluid pressure. And pathologic examinations were also performed. On occluding the caval blood flow, the superior vena caval pressure was sharply and immediately elevated from $103.5{\pm}19.8mmH_2O$ at thoracotomy to $556.4{\pm}86.lmmH_2O$ within 2 minutes to make its plateau thereafter, and the cerebrospinal fluid pressure followed closely the changes of the superior vena caval pressure in its level and pattern being elevated from $102.0{\pm}19.9mmH_2O$ to $490.5{\pm}79.9mmH_2O$. The drops of both the caval and cerebrospinal fluid pressures were definite and marked on opening the shunt flow through the anastomosis, but these postoperative pressures retained still higher ones above their levels measured at thoracotomy. The pathological examinations of the brain and the spinal cord were also performed in six animals. Characteristic changes uniformly seen in all area and in all animals were the findings of capillary congestion and perivascular edema. On the other hand, ischemic nerve cell changes were rather evident, revealing their degrees and extents being related to the prolongation of the time of caval occlusion which has followed by the sustained high pressures in both the superior vena and the cerebrospinal fluid. The experiment suggests the safety of this surgical procedure with minimal, if any, permanent damage as long as the occlusion of the caval blood flow is not prolonged beyond the expected.

• 한국산업보건학회지
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• 제24권2호
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• pp.130-136
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• 2014

Objectives: To evaluate the pulmonary toxicity of Korean Chrysotile(KC), the lung function and the number of fibers in the bronchoalveolar lavage fluid of Sprague-Dawley rats instilled with KC were estimated. Materials: Rats were administered 1 mg KC by a single intratracheal instillation. At each time point(5 days, 5 weeks, 10 weeks), the lung function of the rats was analyzed by pressure transducer and the amount of asbestos in the bronchoalveolar lavage fluid of the rats was calculated by transmission electron microscope equipped with energy dispersive X-ray spectrometer. Results: The lung function of the rats at 5 days after instillation of KC was confirmed to be degraded. However, after 5 weeks the test groups showed a tendency to recover lung function. Still, after 10 weeks the lung function of the test groups had not recovered completely. The number of fibers in the bronchoalveolar lavage fluid of the rats instilled with KC rapidly decreased. At 5 weeks the number of fibers had reduced to approximately 1/2 of that found at 5 days. Over time, at 10 weeks it had rapidly decreased to 1/100 that found at 5 days. Conclusions: Korean chrysotile fibers rapidly decreased in the lungs of rats, but the lung function of rats instilled KC does had not completely recovered by 10 weeks.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.814-816
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• 2002

Because there is a strong interaction between the arc discharge and their surroundings, it is not easy to predict the characteristics of industrial arc plasma systems such as gas circuit breakers. The design procedure of these systems is still largely based on trial and error, although the situation is rapidly improving because of the available computational power at a cost in which is still coming down. The desire to predict the behavior of arc plasma systems, thus optimizing and reducing the develpment cost, has been the motivation of these arc researches. In this paper. we have simulated the switching operation of a gas circuit breaker during high current area using a computational fluid dynamics considered the electric field analysis, the radiation model and the effeects of turbulence.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.237.2-237.2
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• 2010

Although oscillating water column type wave energy devices are nearing the stage of commercial exploitation, there is still much to be learnt about many facets of their hydrodynamic performance. The techniques of Computational Fluid Dynamics (CFD) are applied to simulate a wave energy conversion device in free surface such as waves. This research uses the commercially available ANSYS CFX computational fluid dynamics flow solver to model a complete oscillating water column system with savonius turbine incorporated at the rear bottom of the OWC chamber in a three dimensional numerical wave tank. The purpose of the present study is to investigate the effect of an average wave condition on the performance and internal flow of a newly developed direct drive turbine (DDT) model for wave energy conversion numerically. The effects of blade angle and front lip shape on the hydrodynamic efficiency are investigated. The results indicated that the developed models are suitable to analyze the water flow characteristics both in the chamber and in the turbine. For the turbine, the numerical results of torque were compared for the all cases. The results of the testing have also illustrated that simple changes to the front wall aperture shape can provide marked improvements in the efficiency of energy capture for OWC type devices.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.147-151
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• 2002

Cross flow fan system is widely used for various applications, especially for the air-moving device of heaters, air-conditioners, and air-curtains. Although there are efforts for the optimization of cross-flow fan flow path with different methods of approach, it is still being investigated by many researchers through experimentally and/or theoretically, because the flow pattern of the cross flow fan is not stereotyped. This paper presents some results from numerical experiments for the optimization of the flow path through a cross-flow fan to be applied to indoor wall-mounted room heater. Two dimensional analysis has been applied to a specific fan system including inlet and diffuser outlet. Flow characteristics art presented and discussed for two different flow path at three different operating conditions represented by rotational speed(800, 1,000, 1,200 rpm) of the In. According to the simulated results for the specific fan system under consideration, it could be found that the flow pattern resembles each other at different rotational speed (to say from 800 rpm to 1,200 rpm) for a fixed flow path, while the secondary flows mostly absorbs the speed effects. By changing the flow path significant increase in volume flow rate is estimated upto 2.65 at the same rotational speed. According to the present experience, fan flow path design can be performed more efficiently by incorporating this type of numerical experiments combined with the model tests.

• 한국유체기계학회 논문집
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• 제16권1호
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• pp.17-23
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• 2013

Recently so much attention has been focused on renewable energy and, since its sources to exploit are already almost saturated in the country, the practical alternative to this situation could be a micro-turbine which uses the low head and low flow. From a point of view of local micro-turbine design capacity and manufacturing technology, the problems such as the accumulation of technical skills, the expansion of related industries, the national policy expansion and the turbine efficiency to improve are still vulnerable and it's true that there are also negative views about the economic feasibility, the technicity and the operation management of the micro-turbine. However, if the improvement can be done in technology of low-head double regulation micro-turbine to generate more outputs and the operation management can be reliably realized, the micro-turbine will be re-evaluated as an appliable source of renewable energy, even the output is small, and by a paradigm shift, it could realize a power generation as an economic and rational system.