• 대한기계학회논문집A
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• 제40권1호
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• pp.81-86
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• 2016

밸브는 배관의 유량을 차단 및 제어하기 위한 장치로써 게이트 밸브, 글로브 밸브, 체크 밸브 등 많은 종류가 사용되고 있다. 그 중 글로브 밸브는 고압력 조건에서의 유량조절이 용이하여 LNG 선박, 증기 배관 등에 사용된다. 본 논문에서는 글로브 밸브의 누설 문제를 구조적으로 해결하기 위해 시트의 형상을 변형하는 방법을 제시하였다. 또한 유한 요소 해석을 통해 각 모델의 응력분포와 변형량을 비교하고 이를 통하여 제안한 모델에 대한 검증을 진행하였다. 시뮬레이션 결과 제안된 모델에서 원주 방향의 변형이 줄어들고, 누설을 감소시킬 수 있는 Self-supporting 효과를 확인할 수 있었다.

• ALGAE
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• 제27권4호
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• pp.235-247
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• 2012

Regardless of continuous researches, recent researches on the genus Eucampia (Bacillariophyceae) have focused mainly on E. zodiacus f. zodiacus In the present study, species of the genus Eucampia have been studied based on their morphological characteristics. Eucampia species were collected at 24 sites from July 2008 to June 2011 in Korean coastal waters. Species were mainly identified based on the shape of valve, ocellus, and aperture, along with the length and shape of the bipolar elevations. As a result, five Eucampia species were identified: Eucampia cornuta, E. groenlandica, E. zodiacus f. zodiacus, E. zodiacus f. cylindrocornis, and E. zodiacus var. cornigera. E. cornuta and E. groenlandica have long pervalvar axis length, but the others display short or moderate length. Ocellus shape of E. cornuta, E. groenlandica and E. zodiacus f. cylindrocornis are linear ribs, whereas E. zodiacus f. zodiacus and E. zodiacus var. cornigera have radial ribs with central area. E. cornuta and E. zodiacus f. cylindrocornis have long and narrow cylindrical elevations. E. groenlandica and E. zodiacus f. zodiacus have short and broad elevations with blunt tips. E. zodiacus var. cornigera has long and broad conical elevations. In terms of aperture shape, E. cornuta has large elliptical form, E. groenlandica has almost circular to rounded rectangular form, E. zodiacus f. zodiacus has narrow and elliptical rounded rectangular to a narrow lanceolate form, E. zodiacus f. cylindrocornis has almost rectangular form, and E. zodiacus var. cornigera has rounded rhombic form. On the basis of elevations in broad girdle view, 5 Eucampia taxa could be divided into 3 types: 'narrow H type', E. cornuta and E. groenlandica; 'regular H type', E. zodiacus f. cylindrocornis and E. zodiacus var. cornigera (partial); 'wide H type', E. zodiacus f. zodiacus (almost).

• 한국지열·수열에너지학회논문집
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• 제17권4호
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• pp.79-90
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• 2021

This paper presents a study to reduce the effect of blast pressure on the blast valves installed in protection tunnels, where the shape of the tunnel entrance and the blast pocket is optimized based on the predetermined basic shape of the protective tunnels. The reliability of the numerical tunnel models was examined by performing analyses of mesh convergence and overpressure stability and with comparison to the data in blast-load design charts in UFC 3-340-02 (DoD, 2008). An optimal mesh size and a stabilized distance of overpressure were proposed, and the numerical results were validated based on the UFC data. A parametric study to reduce the blast overpressures in tunnel was conducted using the validated numerical model. Analysis was performed applying 1) the entrance slope of 90, 75, 60, and 45 degrees, 2) two blast pockets with the depth 0.5, 1.0, and 1.5 times the tunnel width, 3) the three types of curved back walls of the blast pockets, and 4) two types of the upper and lower surfaces of the blast pockets to the reference tunnel model. An optimal solution by combining the analysis results of the tunnel entrance shape, the depth of the blast pockets, and the upper and lower parts of the blast pockets was provided in comparison to the reference tunnel model. The blast overpressures using the proposed tunnel shape have been reduced effectively.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2010년도 춘계학술대회
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• pp.407-409
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• 2010

기계장치에 있어서 브레이크 시스템은 기계의 동작시스템 부분들 중에 매우 중요한 역할을 담당하는 부분이다. 만약 기계가 작동 중 멈추지 않으면 사고 시설물 피해 인명 피해 등을 유발할 수 있기 때문이다. 이것은 선박에서 또한 마찬가지이다. 선박에서 항해 중 배를 정지시키기 위해서는 윈드라스 윈치 브레이크 시스템을 사용하고 있으며, 배를 항구에 계류시키기 위해서는 무어링 윈치 브레이크 시스템을 사용한다. 본 연구에서는 배를 항구에 계류시키는 무어링 윈치 브레이크 시스템의 제동력을 향상시키기 위해 기존의 무어링 윈치 브레이크 시스템의 형상 변경한 후 무어링 윈치 브레이크 시스템의 제동력과 강도해석을 실시해 보았다.

• 한국기계연구소 소보
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• 통권18호
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• pp.75-85
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• 1988

유압 펌프 또는 모터, 특히 레이디얼피스톤형 모터, 용 분배기는 동적인 평형상태를 유지하기 위해 양면이 완전히 똑같이 가공된 회전부재와 이 부재의 양면에 동적평형을 보조할 수 있도록 표면에 가공된 형상이 동일한 2개의 고정부재와 이 2개의 고정부재의 간격유지를 위하여 회전부재주위에 사각의 단면적을 갖는 원형링으로 이루어져 있다. 회전부재는 기본적으로 밸브부를 가지고 있으며 평형상태를 보조하기위해 밸브부의 외주에 정압베어링을 설치할 수도 있다. 2개의 고정 부재중 1개는 몇 개의 단이 있는 부재인데 이는 압력상승에 의한 볼트의 인장을 보상하기 위해 밸브케이싱과 축방향의 이동이 가능하도록 하기 위한 방법이다.

• 대한의용생체공학회:의공학회지
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• 제27권6호
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• pp.418-426
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• 2006

In the artificial heart application, productivity and hemodynamic properties of artificial heart valves are crucial in successiful application to long term in vivo trials. This paper is about manufacture and assessment of trileaflet polymer heart valves using vacuum forming process(VFP). The VFP has many advantages such as reduced fabrication time, reproducibility due to relatively easy and simple process for manufacturing. Prior to VFP of trileaflet polymer heart valves, polyurethane(Pellethane 2363 80AE, Dow Chemical) sheet was prepared by extrusion. The sheets were heated and formed to mold shape by vacuum pressure. The vacuum formed trileaflet polymer heart valves fabrication is composed of two step method, first, leaflet forming and second, conduit forming. This two-step forming process made the leaflet-conduit bonding stable with any organic solvents. Hydrodynamic properties and hemocompatibility of the vacuum formed trileaflet polymer heart valves was compared with sorin bicarbon bileaflet heart valve. The percent effective orifice area of vacuum formed trileaflet polymer heart valves was inferior to bileaflet heart valve, but the increase of plasma free hemoglobin level which reflect blood damage was superior in vacuum formed trileaflet polymer heart valves Vacuum formed trileaflet polymer heart valves has high productivity, and superior hemodynamic property than bileaflet heart valves. Low manufacturing cost and blood compatible trileaflet polymer heart valves shows the advantages of vacuum forming process, and these results give feasibility in in vivo animal trials in near future, and the clinical artificial heart development program.

• Investigative Magnetic Resonance Imaging
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• 제12권1호
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• pp.40-48
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• 2008

목적: 개정 도씨 술식과 승모판 고리성형을 동시에 시행한 후 심실의 형태와 기능의 초기 변화를 자기공명영상을 이용하여 평가하고자 하였다. 대상 및 방법: 총 21명의 확장성 심부전 환자를 대상으로 하여 8명에서 개정 도씨 술식을, 6명에서 승모판 고리성형을, 7명에서 두 수술을 동시에 시행하였다. 영화 자기공명영상을 이용하여 수술 전과 후에 좌심실의 형태와 기능을 평가하였다. 좌심실의 이완기말 용적과 수축기말 용적, 장축과 단축의 길이를 측정하고 이로부터 좌심실의 일회박출량, 박출률, 구형지수를 계산하여 구하였다. 이렇게 구해진 인자들을 분석하고 술식이 서로 다른 3군에서 어떻게 다른지 비교하고 두 수술을 동시에 시행할 때의 효과를 해석하였다. 결과: 자기공명영상은 수술 전 $12\;{\pm}\;15$ 일 (범위 1-58 일)과 수술 후 $38\;{\pm}\;50$ 일 (범위 7- 231 일)에 시행하였다. 두 수술을 동시에 시행한 군에서 다른 군에 비하여 수술 전 좌심실의 확장이 더 심하였고 수축력이 더 감소되어 있었다. 수술 후, 좌심실의 이완기말 용적과 수축기말 용적은 수술 형태와 관계없이 모든 환자에서 유의하게 감소하였다. 박출률은 개정 도씨 술식을 받은 환자 군에서만 유의하게 증가하였다 (25.4% to 40.7%). 구형지수는 개정 도씨 술식을 받은 환자에서는 증가하였고 승모판 고리성형을 받은 환자에서는 감소하였다 (0.65 to 0.78 vs. 0.75 to 0.65). 두 수술을 동시에 시행한 환자에서는 유의한 구형지수의 변화가 없었다. 결론: 개정 도씨 술식과 승모판 고리성형을 동시에 시행받은 확장성 심부전 환자에서 좌심실의 형태와 기능의 초기 변화는 좌심실 용적과 일회박출량의 현저한 저하이다. 승모판 고리성형에 의한 구형지수의 감소는 개정 도씨술식에 의한 구형지수의 증가에 의해 상쇄되어 좌심실의 형태는 변하지 않는다. 두 수술을 동시에 시행한 후 좌심실 박출률의 향상은 조기에 일어나지 않는다.

• 건축역사연구
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• 제10권1호
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• pp.9-23
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• 2001

This study is for the Kyungduk-Dan(as a altar of Milsung-Daegun) and The Manun-Jae the characteristics(lay out and planning, window patterns, structure, materials) of the the Korean traditional house during the modern era. Before Manun-Jae was used for the house. The Kyungduck-Dan was constructed in August according to the Lunar Calender in 1927. The Manun-Jae(house for Ki-hun Kang, millionaire ) was completed in 1924. Modern Architectures brought to Korea with the bricks, the tiles, the flash doors, the plate grasses, the brass hardwares. These architectural material was used in positive. During the construction of Manun-Jae in 1924, it happened the architectural exchage among a korean, a chinese and a japanese constructor. Though using the air exhaust valve at the kitchen of Ukyung-Kak( old Anchae), it could be assume that the modern convenience and the improvement of residential environments was considered at that period during the construction of Manun-Jae. That construction was elected with the brick($222mm{\times}106mm{\times}50mm$), the chinese colored tile and plate glass such a modem materials. The new shape of the korean lattice window and the wooden flash-door with glass was used. In Ukyung-Kak, the Chan-Maru(service space) and the kitchen such as a service space or concise utility zone was organically connected. Especially, considered the domesitic activity and circulation, the western kitchen sink and the Chan-Maru(service space) was rationally placed. At the Manun-Jae and the Kyungduck-Dan, the architectural characteristic is that the new shape of windows was used. The lattice window at the Ondol room of Ukyung-Kak, was rgadually added the plate glass and the wood plate. The lattice window with the grid shape at kitchen of that building was adapted japanese grid lattice window in korea at that period. It is the sample that korean traditional house was typically influenced from the japanese resident culture. The Manun-Jae and the Kyungduck-Dan as the modern house kept the form of korean traditional architecture, and was partially adapted a modern characteristic space and modern architectural materials. During the japanese occupancy, these residence can be showed the transition in formally.

• 대한본초학회지
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• 제33권4호
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• pp.43-51
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• 2018

Objectives : Pharbitidis Semen, the seeds of Ipomoea nil (L.) Roth or I. purpurea (L.) Roth, is well-known traditional herbal medicine in Korea. But it is often marketed as a different seed or mixtures of its closely related species. Thus, the present study aims to provide external and micromorphological characters and identification key by using stereoscope (ST) and scanning electron microscope (SEM) for discriminating authentic of Pharbitidis Semen. Methods : A discrimination on external morphological characteristics of sepals, fruits, seeds, and hilum, testa cell micromorphology in the original plants and its congeneric species was carried out using digital calipers, ST, and SEM. Results : Number of valves (degree of apex of each valve), number of seeds per locule, hairy in capsules and size, luster, density of hairy, hilum shape in seeds and shape of cell, anticlinal, periclinal wall in testa may have high discriminative value. The seeds of Ipomoea nil as an original plant of Pharbitidis Semen were distinguished from other species by the relative larger in size, ovoid-trigonous in shape, mostly flabellate or triangular to trapezoid in outline (c.s.), dull, and puberulent in surface and thicken anticlinal wall. Conclusions : On the basis of the results, an identification key of Pharbitidis Semen and closely related species is provided. Our observations suggest that the combination of morphological characters and other studied results could be helpful in the successfully identified authentic herbal medicines. Moreover, micromorphological characters using SEM could be useful for discriminating authentic medicines.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.30-37
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• 2001

Most gasoline engines employ a port injection system to achieve the better fuel-air mixing. A part of injected fuels adheres to the wall or intake valve and forms a film of liquid fuel. The other is secondarily atomized by the spray-wall interaction. A better understanding of this interaction will help in designing injection systems and controlling the strategies to improve engine performance and exhaust emissions. In the present research, the spray-wall interaction was investigated by a laser sheet visualization method. The shape of sprays was pictured at various impinging velocities and angles. The fuel dispersion was estimated by fluorescence light, and the atomization was evaluated by the enlarged images of droplets. The experimental results were compared with model predictions which are based on OPT method. The model has been modified to have the better agreement with the experimental result, and was implemented in the KIVA-II code.