• 제목/요약/키워드: ribs

검색결과 814건 처리시간 0.029초

외부형태 및 해부학적 형질에 의한 큰참나물의 분류학적 위치 (Taxonomic position of Cymopterus melanotiligia (H. Boissieu) C.Y. Yoon based on morphological and anatomical characters)

  • 윤창영
    • 식물분류학회지
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    • 제31권3호
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    • pp.253-265
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    • 2001
  • 한국산 큰참나물에 대하여 외부형태학적 형질 및 엽연부와 분과의 횡단면을 조사하여 분류학적 위치를 밝혔다. 이를 토대로 하여 종의 형태적 특징을 기재하고 분포도를 작성하였으며, 근연 속과의 한계를 명확히 하였다. 큰참나물은 엽연부가 아래로 급격히 돌출하여 ridge 가 형성되고, 분과에서 한쪽은 2개의 측륵과 2개의 중간배륵, 다른쪽은 2개의 측륵과 1개의 배륵이 날개상으로 발달하는 비대칭적 특징을 보여 Angelica s.l.와는 구별되며, Cymopterus 속에 포함되는 것이 타탕하다.

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GIS 립 스페이서에 의한 파괴전압 특성 개선 (Improvement of Breakdown Characteristics Using Ribbed Spacer of GIS)

  • 류성식;최영찬;곽희로
    • 조명전기설비학회논문지
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    • 제15권5호
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    • pp.28-33
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    • 2001
  • 본 논문에서는 금속성 파티클이 GIS 스페이서에 부착되었을 경우 파괴전압특성에 대한 립의 여러 조건에서의 효과를 분석하였다. 립-스페이서의 여러 위치에 금속성 파티클을 부착하고 립의 위치, 길이, 두께 등의 변화에 따른 파괴전압을 측정하여 기조에 제안된 립-스페이서보다 파괴전압을 더욱 향상시킬 수 있는 형상을 제시하고자 하였다. 그 결과 립이 없거나 립이 하나인 스페이서 보다 립이 두 개 있는 형태의 립-스페이서가 전반적으로 가장 양호한 파괴전압 특성을 가지고 있음을 알 수 있었으며, 립의 길이와 두께에 따라서도 파괴전압 특성이 달라짐을 알 수 있었다. 특히 립의 끝단을 라운드 처리함으로써 파괴전압 특성을 더욱 향상시킬 수 있음을 알 수 있었다.

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보강 수지의 종류와 사출성형품의 리브 설계에 따른 휨의 연구 (A Study on the Warpage in Injection Molded Part for Various Rib Design and Reinforced Resins)

  • 이민;이춘규
    • Design & Manufacturing
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    • 제6권1호
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    • pp.67-72
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    • 2012
  • Most of the plastics products have been manufactured by injection molding. Molding trouble in injection-molded parts is caused by changing a molding product and molding process condition, etc. In this study, warpage in the injection molded part have been studied. Specimens are rectangular flat shape with and without ribs. Non-crystalline resins (ABS+GF30%, PC+GF30%) and crystalline resins (PP+GF30%, PA66+GF30%) were used for material. Flat shape ribs showed higher warpage than flat shape without rib by 10 to 41%. the specimens with ribs that are located parallel to flow direction has higher warpage than the specimens with rib that are located perpendicular to flow direction by 11 to 50%. crystalline resins have higher warpage than non-crystalline resins by 22 to 78%. Warpage decreases as packing time increases as injection temperature increases.

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Complex sternal and rib reconstruction with allogeneic material

  • Maliska, Charles Miles III;Archer, Robert Lloyd;Tarpley, Sharon Kaye;Miller III, Archibald Sanford
    • Archives of Plastic Surgery
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    • 제45권6호
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    • pp.593-597
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    • 2018
  • Sternal malunion, or loss, developed after a median sternotomy cannot only be difficult to manage and treat, but also may diminish one's quality-of-life drastically. The technique presented here represents a multispecialty approach in one stage for the reconstruction of an unstable thoracic cage. The procedure utilized a donated sternum and ribs. The sternum with ribs harvested from a single donor included adipose derived stromal vascular fraction (ADSVF) cells with marrow also from the same donor. Autologous muscle flaps, stabilized with acellular dermal matrix were utilized to provide a robust blood supply to the ADSVF cells and bone grafts. Acellular dermal matrix was used to construct the ribs and stabilize the plugs of stem cells and bone. These procedures, in the hands of multispecialty physicians, have led to several successful reconstructions involving complex chest wall deformities. This surgical intervention was performed in a one stage operation. This represents the first successful complete sternal transplant in a patient with return to normal activities and increased quality-of-life.

리브의 높이가 난류 및 열전달특성에 미치는 영향 (Effect of Rib Height on Turbulence and Convective Heat Transfer)

  • 나인;김수진;정효민;정한식;라흐만
    • 동력기계공학회지
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    • 제16권6호
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    • pp.30-37
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    • 2012
  • Effect of rib heights is found as significant parameter to enhance convective heat transfer performance under laminar and low turbulent regime. Circular ribs with different ribheight to channel height ratios, e/H = 0.05, 0.1, 0.15, are fabricated over the copper substrate respectively in a rectangular duct having 7.5 cross sectional aspect ratio. Only one rib pitch to rib height ratio (P/e = 10) has been chosen for all different height ribs. The result shows that the arithmetic average of turbulence intensity decreases with decreasing roughness height calculated between two ribs under laminar and low turbulent region. It occurs because the area of recirculation and reattachment zone also decreases with decreasing rib height. Optimum thermal enhancement factor is derived by 0.1 rib height to channel height ratio under low turbulent region but 0.15 rib height to channel height ratio gives maximum subjected to laminar flow.

사질토 지반에서 강지보를 고려한 신개념 지보시스템에 대한 연구 (A study on the new supporting system using steel ribs in sandy soil)

  • 김상환;김지태;강준구
    • 한국터널지하공간학회 논문집
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    • 제13권5호
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    • pp.395-411
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    • 2011
  • 본 논문은 록볼트를 강지보와 체결한 신개념 지보시스템을 연구하였으며 본 연구를 수행하기 위해 실험 및 수치해석을 실시하였다. 실험적 연구로서 축소모형실험을 사질토지반에서 실시하여 기존의 지보시스템과 신개념 지보시스템을 비교하였으며, 신개념 지보시스템의 축소모형실험 결과를 확인하기 위해 수채해석을 실시하였다. 터널에 신개념 지보시스템을 적용할 경우 터널의 손상을 감소시키는 것을 확인하였다.

Exergetic analysis for optimization of a rotating equilateral triangular cooling channel with staggered square ribs

  • Moon, Mi-Ae;Kim, Kwang-Yong
    • International Journal of Fluid Machinery and Systems
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    • 제9권3호
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    • pp.229-236
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    • 2016
  • Exergetic analysis was introduced in optimization of a rotating equilateral triangular internal cooling channel with staggered square ribs to maximize the net exergy gain. The objective function was defined as the net exergy gain considering the exergy gain by heat transfer and exergy losses by friction and heat transfer process. The flow field and heat transfer in the channel were analysed using three-dimensional Reynolds-averaged Navier-Stokes equations under the uniform temperature condition. Shear stress transport turbulence model has been selected as a turbulence closure through the turbulence model test. Computational results for the area-averaged Nusselt number were validated compared to the experimental data. Three design variables, i.e., the angle of rib, the rib pitch-to-hydraulic diameter ratio and the rib width-to-hydraulic diameter ratio, were selected for the optimization. The optimization was performed at Reynolds number, 20,000. Twenty-two design points were selected by Latin hypercube sampling, and the values of the objective function were evaluated by the RANS analysis at these points. Through optimization, the objective function value was improved by 22.6% compared to that of the reference geometry. Effects of the Reynolds number, rotation number, and buoyancy parameter on the heat transfer performance of the optimum design were also discussed.

유출유동 및 각도진 요철이 회전하는 사각덕트 내 열전달분포에 미치는 영향 (Effects of Bleed Flow and Angled Ribs on Heat Transfer Distributions in a Rotating Square Channel)

  • 박석환;전윤흥;김경민;이동현;조형희
    • 대한기계학회논문집B
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    • 제31권1호
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    • pp.76-82
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    • 2007
  • The present study investigated the effects of channel rotation and bleed flow on heat/mass transfer in a square channel with $45^{\circ}$ rib turbulators. The bleed holes were located between the rib turbulators on the leading surface and those on the trailing surface case by case. The tests were conducted under the conditions of various bleed ratios (0.0, 0.2, 0.4) and rotation numbers (0.0, 0.2, 0.4) at Re=10,000. The results suggested that heat/mass transfer characteristics were influenced by the Coriolis force, decrement of main flow rate, secondary flow by angled ribs and bleed hole location. As the bleed ratio (BR) increased, the heat/mass transfer decreased on both surfaces due to the reduction of main flow rate. With increment of the rotation number, heat/mass transfer also decreased and almost the same because the reattachment of the secondary flow induced by angled ribs was weakened on the leading surface and the secondary flow was disturbed on the trailing surface by the Coriolis force.

Improvements to the analysis of floorbeams with additional web cutouts for orthotropic plated decks with closed continuous ribs

  • De Corte, Wouter;Van Bogaert, Philippe
    • Steel and Composite Structures
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    • 제7권1호
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    • pp.1-18
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    • 2007
  • Additional cutouts in the floorbeam webs of orthotropic plated bridge decks relieve the highly stressed lower flange of the ribs passing through these floorbeam webs from possible fatigue damage. Conversely, the floorbeam webs themselves suffer from high stress concentrations, especially along the free edges of the additional cutouts. These stresses result from a combination of direct introduction of vertical traffic loads in the weakened web and from the truss action of the floorbeam. The latter differs from a simple beam action due to the presence of the openings and corresponds more to the behaviour of a Vierendeel truss. Close assessment of the appearing stresses, highly relevant for fatigue resistance, requires the use of elaborate finite element modelling. However, a full finite element analysis merely provides the results of total stresses, leaving the researcher or designer the difficult task of finding the origin of these stress components. This paper presents a calculation method for cutout stresses based on a combination of a framework analysis and a two dimensional finite element analysis of much smaller parts of the floorbeam. This method provides more insight in the origin of the stress components, as well as it simplifies any comparison of different additional cutout geometries, independent of the floorbeam topology.

리브로 보강된 GFRP 관로의 탄성 좌굴거동 특성 (Elastic Behavior Characteristics of GFRP Pipes Reinforced Ribs)

  • 한택희;서주형;염응준;강영종
    • 한국강구조학회 논문집
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    • 제18권6호
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    • pp.737-746
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    • 2006
  • 본 연구에서는 리브로 보강된 GFRP(Glass Fiber Reinforced Plastic) 관로의 탄성 좌굴 강도를 산정하였다. 보강된 리브의 두께, 높이, 배치 간격은 관로의 좌굴 강도에 영향을 미치는 주요 인자이다. 또한, GFRP 재료는 이방성 재료이므로, 재료의 방향별 강성 또한 관로의 좌굴강도에 영형을 미치는 인자로서 고려되어야할 부분이다. 이러한 매개변수를 적용하여, 직교 이방성 재료로 구성된 리브 보강 관로의 좌굴 강도를 유한요소 해석을 이용하여 매개변수를 수행하고, 회귀분석을 통하여 좌굴 강도 산정을 위한 간략식을 제시하였다.