• 제목/요약/키워드: flat plate system

검색결과 344건 처리시간 0.025초

광감도 비교를 통한 면외 변형 측정 조건에 대한 연구 (Study on the Out-of-Plane Deformation Measurement Condition through Comparison Photosensitivity)

  • 김현호;강찬근;이현준;정현철;김경석;홍정기
    • 한국정밀공학회지
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    • 제32권9호
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    • pp.807-813
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    • 2015
  • In the present study, an interferometer system, which integrates the laser sensitivity control technique based on the theory of electronic speckle pattern interferometry, one of non-contact non-destructive analysis methods, was developed. This interferometry system receives an image from CCD cameras for each reference and object, and compares the photosensitivity of the object and reference images from imagification. For the purpose of this study, the photosensitivity of object and reference light is measured with power meters, and the amount of light was controlled with an ND filter with a reference light port matching photosensitivity. Using the plate specimen as the object, 0.6, 0.9, 1.2, and $1.5{\mu}m$ of out-plane deformation was made, and images were compared according to the difference in photosensitivity. After analysis, larger object deformations showed larger numbers of stripe patterns. Images became clearer and data error was reduced when the photosensitivity of object and reference light matched.

왕겨 연소기(燃燒機)를 이용(利用)한 온수(溫水)보일러 시스템 개발(開發) (I) -실험적(實驗的) 연구(硏究)- (Development of a Hot Water Boiler System with a Rice Hull Furnace)

  • 이용국;박승제;백풍기;노상하
    • Journal of Biosystems Engineering
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    • 제12권4호
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    • pp.31-43
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    • 1987
  • This study was performed to develop a hot water boiler system with small scale automatic rice hull furnace for the multi-purpose use in the farm. For the experiment a prototype hot water boiler system with rice hull furnace was fabricated, which was equipped with automatic hull feeder, igniter and ash removal device. Optimum operational conditions of the prototype: system were analyzed. The results arc summarized as follows. 1. The temperature measured right above the burning surface should be higher than $500^{\circ}C$ combustion. 2. The top zone of the combustion chamber was the most suitable location of the thermocouple to pick up the control temperature for the automatic operation of the rice hull furnace. 3. The content of carbon monoxide in the flue gas was increased with the filling height of burning material but it was less than 0.3 percent in volume in this experiment. When the filling height was expressed as the ratio of rice hull feed rate to the volume of the combustion chamber above the burning surface, the optimum ratio was about $150kg/m^3-h$. 4. The combustion efficiency of the prototype was higher than 95 percent when the feed rate was 1.1 to 2.3 kg/h and moisture content of rice hull was 22.4 percent (w.b.) or less. 5. It was estimated that the optimum operational conditions of the system were 1.3 to 2.0 kg/h in feed rate, 70 to 100 percent in excess air and 500 to $510^{\circ}C$ in control temperature. 6. The efficiency of coil heal exchanger increased with a decrease in feed rate of rice hull. When the rice hull feed rates were 1.1, 1.7 and 2.3 kg/h, the efficiencies of coil heat exchanger were about 34, 30 and 25 percent and heat transfer rates were 5.7, 7.6 and 8.8 MJ/h, respectively. When the flat plate heat exchanger was used in addition to the coil heat exchanger, the efficiency of the heat exchanger system increased to 48 percent.

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설비공학 분야의 최근 연구 동향 : 2016년 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 2016)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제29권6호
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. 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 flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (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 of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth 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, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving 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 analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

Application of unified equivalent frame method to two-way slab structures with beams

  • Choi, Seung-Ho;Lee, Deuck Hang;Oh, Jae-Yuel;Cho, Hae-Chang;Lee, Jae-Yeon;Kim, Kang Su
    • Computers and Concrete
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    • 제22권4호
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    • pp.365-372
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    • 2018
  • The current design codes present an equivalent frame method (EFM) for the analysis and design of two-way slab structures. However, since the EFM was developed to be suitable for two-way slab structures subjected to gravity loads only, it brings many problems in its application to the analysis of two-way slabs to which gravity and lateral loads are applied simultaneously. Therefore, authors proposed the unified equivalent frame method (UEFM) that can analyze the structural behavior of flat-plate slab systems subjected to gravity and lateral loads in their previous studies. In this study, the UEFM was modified to be applicable to the two-way slab system with beams. In addition, the accuracy of the proposed UEFM was then examined by comparing it to the lateral behaviors of the two-way slab specimens.

아크형 날개를 이용한 항력식 수직축 소형 풍력 터빈 설계 (Design of Drag-type Vertical Axis Miniature Wind Turbine Using Arc Shaped Blade)

  • 김동건;김문경;차득근;윤순현
    • 한국유체기계학회 논문집
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    • 제9권2호
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    • pp.7-12
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    • 2006
  • This study is to develop a system of electric power generation utilizing the wind resources available in the domestic wind environment. We tested drag-type vortical wind turbine models, which have two different types of blades: a flat plate and circular arc shape. Through a performance test, conditions of maximum rotational speed were found by measuring the rpm of wind turbine. The rotational speed was measured by a tachometer in a wind tunnel and the tunnel wind speed was by using a pilot-static tube and a micro manometer. The performance test for a prototype was accomplished by calculating power, power coefficient, torque coefficient from the measurement of torque and rpm by a dynamometer controller From the measurements for miniature turbine models with two different blades, the circular arc shape was found to Produce a maximum rotational speed for the same wind velocity condition. Based on this result, the prototype with the circular arc blade was made and tested. We found that it produces 500W at the wind velocity of 10.8 m/s and the power coefficient was 20%.

초음속 유동장에서의 충돌제트 특성에 대한 실험적 연구 (An experimental study on the characteristics of transverse jet into a supersonic flow field)

  • 박종호;김경련;신필권;박순종;길경섭
    • 한국군사과학기술학회지
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    • 제6권4호
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    • pp.124-131
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    • 2003
  • When a secondary gaseous flow is injected vertically into a supersonic flow through circular nozzle, a complicated structure of flow field is produced around the injection area. The interaction between the two streams produces a strong bow shock wane on the upstream side of the side-jet. The results show that bow shock wave and turbulent boundary layer interaction induces the boundary layer separation in front of the side-jet. This study is to analyze the structure of flow fields and distribution of surface pressure on the flat plate according to total pressure ratio using a supersonic cold-flow system and also to study the control force of affected side-jet. The nozzle of main flow was designed to have Mach 2.88 at the exit. The injector has a sonic nozzle with 4mm diameter at the exit of the side-jet. In experiments, The oil flow visualization using a silicone oil and ink was conducted in order to analyze the structure of flow fields around the side-jet. The flow fields are visualized using the schlieren method. In this study, a computational fluid dynamic solution is also compared with experimental results.

In-bin 건조 및 저장체계에 관한 실험적 연구 (Experimental Study on In-bin Drying and Storage System)

  • 고학균;정창주
    • Journal of Biosystems Engineering
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    • 제5권2호
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    • pp.15-25
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    • 1980
  • 본 연구는 현재 국내 농촌에서 문제시되고 있는 벼의 건조와 저장방법을 개선하기위한 한 가지 방법으로써 Grain bin의 이용에 따른 기술적인 적용가능성을 구명하는데 있었으며 건조열원으로서는 상온공기와 Solar collector 에 의한 보충가열공기를 사용하였다. 건조시험에서는 벼의 건조속도, 층별함수율의 변화, 동력소모량, 도청수율 등을 측정 비교하였으며 건조가 완료된 후에는 저장시험도 아울러 실시하였다. 본 시험을 통하여 얻은 결과는 다음과 같다. 1. 본시험에 사용된 Solar Collector 는 집열면적이 $27.7m^2M$의 Flat-plate 형식이며 내부에 태양열의 저장모체로서 약 $7m^2M$의 검은 돌을 사용하였다. Collector 의 효율은 35%이었으며 Collector를 통과하여 Bin으로 들어가는 공기의 온도는 외기온에 비하여 주간에는 약 $4^\circ C$, 야간에는 약 $8^\circ C$, 정도 상승된 것으로 나타났다. 2. 상온공기와 Collector를 이용한 건조험결과 안전저장함수율에 도달하는 데 약 7일과 약 5일이 소요되었다. 3. 태양열 건조는 상온통풍건조에 비하여 곡물층간의 함수율차이가 약간 크게 나타났으나 건조속도가 빠를뿐만 아니라 동력소모량도 적은 것으로 분석되었다. 4. 건조시험이 완료된 직후 이차에 걸쳐 Bin 내에서 저장시험을 실시한 결과 저장기간중 벼의 안전보전이 가능했으며 평균함수율이 12.0~14.5%범위에서 유지되었다.

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유체에 부분적으로 둘러싸인 사각형 용기의 접수진동 (Hydroelastic Vibration of a Rectangular Tank Partially Surrounding with a Liquid)

  • 정경훈;김종욱
    • 한국소음진동공학회논문집
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    • 제25권3호
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    • pp.207-215
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    • 2015
  • This paper deals with a theoretical method to calculate natural frequencies of a fixed-free rectangular tank partially in contact with an outer water gap. Orthogonal polynomials satisfying the boundary conditions of the tank are used as admissible functions in the Rayleigh-Ritz method. A quarter model of the liquid-coupled system is constructed and it is simplified to a line supported flat plate in contact with the liquid. The liquid displacement potential functions satisfying the Laplace equation and water boundary conditions are derived, and the finite Fourier transform is accomplished in conjunction with the compatibility requirement along the contacting interfaces between the tank and water. An eigenvalue problem is derived so that the natural frequencies of the wet rectangular tank can be extracted. The predictions from the proposed analytical method show good agreement with the finite element analysis results.

보조공동을 이용한 초음속 공동내부의 압력진동 저감에 관한 연구 (A Study on the Reduction of Supersonic Cavity Pressure Oscillations Using a Sub-Cavity System)

  • 신춘식;정준창;;김희동
    • 한국추진공학회지
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    • 제13권5호
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    • pp.41-47
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    • 2009
  • 2차원 초음속 공동유동에서 발생하는 압력진동을 제어하기 위한 목적으로, 본 연구에서는 수치해석적 연구를 수행하였다. 본 계산에서는 압력진동을 제어하기 위하여 보조공동의 형상을 변화시켰으며, 유동의 마하수를 1.50, 1.83 그리고 2.50로 변화시켰다. 그 결과, 보조공동은 압력진동을 상당히 감소시켰으며, 압력진동의 제어효과는 유동의 마하수와 보조공동의 상세형상에 크게 의존함을 알았다.

200kW 탑형 태양열발전시스템에서 사용되는 Heliostat의 집열특성 분석 (Analysis of Energy Concentration Characteristics of Heliostat used in 200kW Tower Type Solar Thermal Power Plant)

  • 박영칠
    • 한국태양에너지학회 논문집
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    • 제31권3호
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    • pp.80-88
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    • 2011
  • Heliostat in the tower type solar thermal power plant is a sun tracking mirror system to reflect the solar energy to the receiver and the optical performance of it affects to the efficiency of whole power plant most significantly. Thus a solid understanding of heliostat's energy concentration characteristics is the most important step in designing of the heliostat field and the whole power plant. The work presented here is the analysis of energy concentration characteristics of heliostat used in 200kW solar thermal power plant, where the receiver located at 43m high in tower has $2{\times}2$m rectangular shape. The heliostat reflective surface is formed by 4 of $1{\times}1$m flat plate mirror facet and the mirror facet is mounted on the spherical frame. The direct normal incident radiation models in vernal equinox, summer solstice, autumnal equinox and winter solstice are first derived from the actually measured data. Then the intercept ratio, heat flux distribution and total energy collected at the receiver for the heliostats located in the various places of the heliostat field are investigated. Finally the effect of mirror facet installation error on the optical performance of the heliostat is analyzed.