• 한국해양공학회지
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• 제34권2호
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• pp.66-76
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• 2020

A light buoy is equipped with lighting functions and navigation signs. Its shape and colors indicate the route to vessels sailing nearby in the daytime, with its lights providing this information at night. It also plays a role in notifying the presence of obstacles such as reefs and shallows. When a light buoy operates in the ocean, the visibility and angle of light from the lantern installed on the buoy changes, which may cause them to function improperly. Therefore, it is necessary for the buoy to have stable and minimal motions under given environmental conditions, mainly waves. In this study, motion analyses for a newly developed lightweight light-buoy in waves were performed to predict the motion performance and determine the effect of the developed appendages for improving the motion performance. First, free decay tests, including benchmark cases, were performed using computational fluid dynamics (CFD) to estimate the viscous damping coefficients, which could not be obtained using potential-based simulations. A comparison was made of the results from potential-based simulations with and without considering viscous damping coefficients, which were estimated using CFD. It was confirmed that the pitch and heave motions of the buoy became smaller when the developed appendages were adopted.

• 한국전산유체공학회지
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• 제20권4호
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• pp.21-27
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• 2015

Flow field around the KRISO 3600TEU container ship is computed using a surface generated based on interpolations of station lines, which are given in a body plan of the ship, without using any CAD program. An interpolation method is suggested based on inscribed circles to generate curves between two neighboring station lines. The interpolated surface is saved in a STL format to use the snappyHexMesh utility of the openfoam. Computed resistance of the ship is compared with experimental and other computational results and the effects of the interpolation of neighboring station lines on the computed resistance are investigated. The suggested method is applied to calculate the flow field around a submarine with appendages. The surface triangulations for the hull and the appendages are generated without consideration of each other, then those surface triangulations are simply combined to provide a grid generator with the body boundary. The junctures of the hull and the appendages are identified automatically during the grid generation procedure. Tip vortex is captured, which travels downstream from the tip of the appendages.

• Journal of Chest Surgery
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• 제26권12호
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• pp.909-914
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• 1993

Complete and optimal visualization of the mitral apparatus is a prerequisite for accurate repair or replacement of the mitral valve. A vertical left atriotomy just posterior to the interatrial groove is the most commonly used approach. However,exposure can be difficult under certain circumstances,such as small left atrium or reoperation. Other approaches have been advocated to deal with this difficult situations. We used an extended transseptal approach in 10 patients and good clinical results and excellent educational effects were obtained. The extended transseptal approach combines two semicircular atrial incisions circumscribing the tricuspid and mitral annuli anteriorly and superiorly,allowing exposure of the mitral valve by deflecting the ventricular side using stay sutures. The right atrium is opened anteriorly along the atrioventricular sulcus. The atrial septum is incised vertically through the fossa ovalis. Right atrial and septal incisions are joined at the superior end of the interatrial septum and extended across the dome of the left atrium to the left atrial appendage. The mitral valve was replaced in all 10 patients. Four of 10 patients had other simultaneous valve procedure: one had aortic valve replacement: 2 underwent tricuspid annuloplasty: 1 had aortic valve replacement and tricuspid annuloplasty. There was no hospital death and complication. Among the 5 patients who had atrial fibrillation preoperatively,4 had atrial fibrillation postoperatively,1 converted to sinus rhythm. The five patients who were in normal sinus rhythm preoperatively remained in sinus rhythm after replacement. A review of our results with this approach confirms the efficacy and safty of this method. So we recommanded this approach for routine mitral valve procedure,especially difficult situations,such as a small left atrium or the redo operation.

• 대한조선학회논문집
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• 제48권4호
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• pp.357-362
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• 2011

It has been often reported that a water-jet propelled high speed vessel lost the course keeping ability in seaway. In this study, model tests of a high speed vessel were performed to measure the running attitude and to check the course keeping ability. The model ship may lose the course keeping ability due to bad running attitudes such as bow drop. So model tests were carried out to improve the running attitude by changing the position of longitudinal center of gravity and using appendages at the bow and the stern of a model. The position of lateral center of pressure moved toward stern and the course keeping ability was improved by modifying the transom wedge angle.

• 대한조선학회논문집
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• 제32권2호
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• pp.43-55
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• 1995

평판 위에 놓여진 스트럿(strut) 주위의 난류유동을 MAC 방법에 의하여 수치계산하였다. 난류 모델은 Baldwin-Lomax 모델이며 평판과 스트럿의 접합부 부근에서의 처리를 위하여 Buleev의 m2ixing length를 도입하였다. 계산결과의 검증을 위하여 DTRC의 풍동 실험 결과와 비교하였다. 실험에서 나타난 horseshoe vortex가 계산에서도 재현되는 등 전반적으로 계산결과와 실험결과 간에 좋은 일치를 볼 수 있었다. 그러나 접합부에서 극히 가까운 부근과 스트럿의 후류에서는 불일치를 보여 이 곳에서의 난류모델의 개선이 필요한 것으로 보여졌다. 결론적으로 평판과 스트럿의 접합부 부근의 유동을 계산함에 있어서 Baldwin-Lomax 모델은 도입된 많은 단순화를 위한 가정에도 불구하고 실용적으로 유용한 결과를 주는 것으로 보여진다.

• 한국군사과학기술학회지
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• 제21권1호
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• pp.10-16
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• 2018

The Republic of Korea Marine Corps is planning to develop a new amphibious assault vehicle which is able to operate with higher water speed than current KAAV. In order to achieve a higher water speed for hydrodynamically bulff-body vehicles, it is essential to develop drag reduction strategies. In this paper, resistance characteristics including trim angles of amphibious assault vehicles with several appendage designs are investigated using a commercial CFD code, STAR-CCM+. The computed results are compared with experimental data conducted at the towing tank with 1:4.5 scaled model and show good correlation. Comparing with the results of bare hull, 3.4 % of hydrodynamic drag and 52 % of trim angle are reduced by the application of double angled bow flap and a hydrofoil attached at the transom.

• 한국의류산업학회지
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• 제13권3호
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• pp.398-408
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• 2011

This study shows that the self-satisfaction individually is rising and social life is attracted effective and successful in image making field by structuring the facial image improvement program through experimental study in order to improve unbalance of women's face. Experiment is conducted by electing 3 samples for 12 weeks and analyzing the measurement and visual analysis, infrared thermography, and evaluation of experts in order to check the facial unbalance. Subject 1 had the effect at approximately in 4 weeks with the severely distorted chin line and mouth appendage. The facial outline became softer to turn entire image to be softer and more feminine. Subject 2 had the severe distortion of location and size of eyes and nose. But the skin was getting better at first, followed by eyes getting clearer with the location changed in left and right. Subject 3 had the twisted nose and lower chin, but after two weeks, the eye area and skin were better and the width of left and right chin was similarly changed. On the basis of the above research result, the program to effectively improve the image was structured and presented with the resolution of facial unbalance. Program is consist of the training of breathing method, face washing method, facial muscle exercise.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권1호
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• pp.25-34
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• 2017

The concentric dual-buoy Wave Energy Converter (WEC), which consists of external buoy (hallow-cylinder) with toroidal appendage and cylindrical internal buoy within the moon-pool is suggested in this research and its performance in various wave conditions is studied. The Linear Electric Generator (LEG), consisting of a permanent magnet and coils, is used as a direct Power Take-Off (PTO) system. To maximize the electrical energy extracted from the PTO system, the relative heave motions between the dual buoys must be highly amplified by the multiple resonance phenomena of dual-buoy and internal-fluid motions. The high-performance range can be widened by distributing those natural frequencies with respect to the peak frequency of the wave spectrum. The performance of the newly developed dual-buoy WEC was measured throughout the systematic 1:5.95-model test in regular and irregular waves conducted in a wave tank at Seoul National University. The model-test results are also validated by an independently developed numerical method.

• 한국해양공학회지
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• 제18권4호
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• pp.71-76
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• 2004

A Study of the traditional Korean fishing boat is based on a report on an investigation of the Korean fishing boats, conducted in 1921. The report was completed in 1927 with the conclusion of the Southern Sea region and West Sea region studies, which included the investigation oj the entire region. It was a very thorough and scientific investigation of Korean fishing boats, which has been published in three volumes. Based on this report, this paper surveys the characteristics and the hull form of the traditional Korean fishing boats. As a result, we find ${\cdot}out$ that the hull form of the traditional Korean fishing boat is very similar to that of modern sailing boat. Thus, it is a good candidate for the development of the modern sailing boats for the Korean Sea.

• Journal of Chest Surgery
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• 제16권3호
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• pp.331-336
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• 1983

Cor triatriatum is a rare congenital malformation of the heart, in which a septum stretches in a transverse or oblique plane through the left atrium, thus separating it into two compartments. The upper one connects with the pulmonary veins, and the lower one connects with the left ventricle. Due to the rarity of, and great difficulty in-diagnosing, cor trlatrlatum, data On the surgery of this disease are of necessity very limited and so accurate pre-operative diagnosis was very difficult to make. `We experienced a case of the cyanotic congenital heart disease which was diagnosed as a large atrlal septal defect with streaming venous blood from inferior vena cava to left atrium through atrial septal defect in August, 1982. We found that there were transverse septum in the left atrium through atrlal septal defect, the pulmonary venous drainage were located in the upper chamber of the left atrium, and the lower chamber was connected with the left atrial appendage, mitral valve and `left ventricle. But our case had not any opening in this transverse septum and the right atrium was connected with the upper chamber of the left atrium through the upper part of the atrlal septal defect, and was communicated with the lower chamber of the left atrium through the lower part of the atrlal septal defect. We excised the transverse septum and repair this atrial septal defect with Woven Dacron patch accompanying with the drainage of coronary sinus to right atrium. The post-operative course was not eventful and he was discharged with good result on the post-operative 8th day, and has been in good .condition up to now for longer than 10 months.