• 제목/요약/키워드: rib-plate

검색결과 147건 처리시간 0.024초

CFD를 활용한 태양열 공기가열기 내 사각저항체 설치 조건에 따른 열전달 및 압력강하에 관한 연구 (Research on the Heat Transfer and Pressure Drop by Installation Conditions of Rectangular Obstacle in a Solar Air Heater Based on CFD)

  • 최휘웅;김영복;손창효;윤정인;최광환
    • 한국태양에너지학회 논문집
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    • 제39권1호
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    • pp.77-89
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    • 2019
  • The solar air heater has various performances according to an obstacle installed in the air duct. Many studies on thermal performance have been conducted. But many of these studies were using a kind of rib type obstacle attached at the bottom of absorbing plate, but they are so hard to be manufactured. In this study, characteristics of the heat transfer and pressure drop in the solar air heater with various horizontal rectangular obstacles was investigated by CFD (Computational Fluid Dynamics) analysis. As a result, the heat transfer performance was improved from 1.2 to 3.32 times depending on installation conditions of rectangular obstacle. The pressure drop, however, also increased with increment of heat transfer performance from 2.8 to 180 times only by changing installation conditions of rectangular obstacle. Thus, the performance factor presenting the thermal performance enhancement on the same pressure drop was also confirmed. As a result, the highest value of 0.828 as better performance factor was obtained at the lower height of rectangular obstacle and this value has started to decrease with increment of heat transfer performance. In the end, it could be confirmed that the pressure drop was carried higher than the quantity of improvement of the heat transfer performance when the heat transfer performance was increased by change of installation conditions of rectangular obstacle. Both heat transfer enhancement and pressure drop to be required for system need to be considered before the rectangular obstacles are applied to the solar air heater.

Optimum arrangement of stiffener on the buckling behaviour of stiffened composite panels with reinforced elliptical cutouts subjected to non-uniform edge load

  • Kalgutkar, Akshay Prakash;Banerjee, Sauvik;Rajanna, T.
    • Steel and Composite Structures
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    • 제42권4호
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    • pp.427-446
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    • 2022
  • Cutouts in the beams or plates are often unavoidable due to inspection, maintenance, ventilation, structural aesthetics purpose, and sometimes to lighten the structures. Therefore, there will be a substantial reduction in the strength of the structure due to the introduction of the cutouts. However, these cutouts can be reinforced with the different patterns of ribs (stiffener) to enhance the strength of the structure. The present study highlights the influence of the elliptical cutout reinforced with a different pattern of ribs on the stability performance of such stiffened composite panels subjected to non-uniform edge loads by employing the Finite element (FE) technique. In the present formulation, a 9-noded heterosis element is used to model the skin, and a 3-noded isoparametric beam element is used to simulate the rib that is attached around a cutout in different patterns. The displacement compatibility condition is employed between the plate and stiffener, and arbitrary orientations are taken care by introducing respective transformation matrices. The effect of shear deformation and rotary inertia are incorporated in the formulation. A new mesh configuration is developed to house the attached ribs around an elliptical cutout with different patterns. Initially, a study is performed on the panels with different stiffener schemes for various ply orientations and for different stiffener depth to width ratios (ds/bs) to determine an optimal stiffener configuration. Further, various parametric studies are conducted on an obtained optimal stiffened panel to understand the effect of cutout size, cutout orientation, panel aspect ratio, and boundary conditions. Finally, from the analysis, it can be observed that the arrangement of the stiffener attached to a panel has a major impact on the buckling capacity of the stiffened panel. The stiffener's depth to width ratio also significantly influences the buckling characteristic.

호텔 양식당의 스타메뉴 개발에 관한 탐색적 연구 -서울지역 특1급 호텔을 중심으로- (A Exploratory Study on the Development of Star Menus in the Western Restaurants of the Hotels Focused on the Tourism Hotels in Seoul)

  • 이은정;이종길
    • 한국식생활문화학회지
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    • 제21권6호
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    • pp.629-637
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    • 2006
  • This exploratory study is to analyze the status of star menus and suggest the development strategy of star menus in the western restaurants of the tourism hotels in Seoul. The data was collected from the chefs who have been working over 15-years in tourism hotels in Seoul by judgement sampling. The questionnaire was composed of Miller and Pavesic's 'Fifty tips for a successful menu' and Khan's 'The evaluation of menu item development', The 30-menu items were selected from the 1st survey on the menu items that were high in both popularity and contribution margin by menu engineering method. The selected menu items were analyzed by 14 lists: simplicity, ready availability of ingredients, quality, flavor, presentation, preparation, service method, nutrition quality, preference, profitability, serving temperature, descriptive copy of menu and publicity. As a result of the study, appetizer category was recorded the highest score by 4.09. Smoked salmon, Tomato and mozzarella cheese, Cream of mushroom, Cream of asparagus, French onion soup, Grilled beef tenderloin, Grilled rib-eye steak, Roasted lamb rack, King prawn, Seafood spaghetti, Chef's salad, Caesar salad, Organic salad, Fruit plate, Italian tiramisu and Yogurt ice cream were recorded high score. The development strategy of star menu is belows : the menu writer must consider the productivity, effectiveness, popularity and profitability, the regular customers want varieties and creativity in the menu and the operators have to include the star menu items in the set menu.

주행차량에 따른 개단면 강바닥판 교량의 국부거동 특성 (Characteristic of Local Behavior in Orthotropic Steel Deck Bridge with Open Ribs according to Running Vehicle)

  • 이성진;경갑수;박진은;이희현
    • 한국강구조학회 논문집
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    • 제24권1호
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    • pp.101-108
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    • 2012
  • 강바닥판 교량은 비교적 얇은 강판이 사용되며, 가로 세로리브 및 가로보 등의 구조부재가 용접에 의해 복잡한 형상으로 조립되므로 용접에 의한 변형과 결함이 발생할 가능성이 매우 높고, 용접연결부에서의 응력 상태가 매우 복잡하다. 또한 실제 강바닥판 교량에서의 피로균열은 주부재보다 2차부재와의 용접연결부에서 발생되고 있다. 그러나 강바닥판교량 설계시에는 대부분 주부재에 대한 응력 평가가 이루어지고 있으며, 피로균열이 발생하는 구조상세에 대한 상세 응력 평가 및 특성 분석은 거의 검토되고 있지 있다. 본 연구에서는 공용년수 29년된 개단면 세로리브를 가진 강바닥판을 대상으로 피로균열의 원인을 조사하고, 재하시험 및 실교통류 흐름하에서의 현장계측을 통하여 대상 교량의 피로안전성을 검토하였다. 또한 피로균열이 발생된 세로리브 및 다이아프램의 용접부를 대상으로 격자해석 및 상세해석 모델을 사용하여, 이들 구조상세에 대한 영향면해석을 이용하여 이동하중에 따른 거동 특성을 조사하고, 대상교량의 피로균열 발생 원인을 규명하였다.

고강도 격자지보재의 개발 및 그 성능 평가 (Development of High Strength Lattice Girder and Evaluation of Its Performance)

  • 이재원;민경남;정지욱;노병국;이상진;안태봉;강성승
    • 지질공학
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    • 제30권1호
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    • pp.43-57
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    • 2020
  • 본 연구는 기존의 강지보재보다 우수한 고강도 격자지보재를 개발하여 그 성능을 평가하기 위함이다. 이를 위해 수치해석을 이용한 지보재의 구조적 특성을 분석하였고, 시작품에 대한 최대 굽힘하중시험과 용접이음부 인장강도시험을 실시하여 그 성능을 평가하였다. 구조해석 결과에 따른 최적의 상하부부재와 플레이트의 규격은 50 mm × 31.8 mm × 25.4 mm로 시공성과 경제적이 우수한 것으로 나타났다. 굽힘 하중시험으로부터 확정된 규격 55 mm × 30 mm × 20 mm와 85 mm × 30 mm × 20 mm의 고강도 격자지보재는 기준값과 H형강 100과 125의 목표값 모두 만족하는 것으로 나타났다. 이론 처짐량과 실제 처짐량의 비를 검토한 결과, 이 연구에서 개발된 고강도 격자지보재는 독일연방 철도국에서 제시하고 있는 격자지보재 처짐량의 평가기준 5 이하로 나타났다. 마지막으로 용접이음부에 대한 인장시험 결과는 고강도 격자지보재의 주봉-보조봉-플레이트가 접하는 용접이음부 인장강도가 목표값 이상으로 나타나 용접이음부에 대한 안정성은 충분한 것으로 나타났다.

자기이방성센서를 이용한 강판의 비파괴 응력 계측에 관한 연구 (A Study on Non-destructive Stress Measurement of Steel Plate using a Magnetic Anisotropy Sensor)

  • 김대성;문홍득;유지형
    • 한국지반환경공학회 논문집
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    • 제12권11호
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    • pp.71-77
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    • 2011
  • 최근 들어 자기이방성센서를 이용한 비파괴응력계측기법은 강교나 강관 등의 건설 분야에서 적용되어지고 있다. 또한 터널건설현장에서 이용되는 강지보재에 대해서도 적용한 사례가 있다. 본 연구에서는 일본에서 개발된 자기이방성센서와 스트레인 게이지를 이용하여 국산 강재인 SS400에 적합한 응력감도곡선을 도출하기 위해 강재하중재하실험을 수행하였다. 또한 자기이방성센서를 이용한 비파괴 응력계측기법의 적용성을 평가하기 위하여 추가 강재하중재하실험과 수치해석을 실시하였다. 본 연구의 결과, 계측위치에 따라 자기이방성센서에서 측정된 출력전압과 스트레인 게이지로 측정된 응력의 평균을 이용하여 국산 강재인 SS400에 적합한 응력감도곡선을 도출하였다. 그리고 추가 강재하중재하실험과 수치해석을 비교한 결과, 자기이방성센서의 오차범위가 약 20MPa 정도임을 알 수 있었다. 자기이방성센서를 강재의 응력상태를 파악할 목적으로 사용할 경우, 강재의 항복응력의 레벨(245MPa)을 고려하면 공학적으로 충분한 정확도를 가지고 있다고 판단된다. 특히 자기이방성센서는 계측 센서가 부착되어 있지 않은 강구조물에서 잔류응력을 고려한 현재상태의 응력을 용이하게 파악할 수 있으며, 강구조물의 유지관리에 편리하게 적용이 가능함을 확인하였다.

설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제27권7호
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.