• 제목/요약/키워드: Air-bubble sheet

검색결과 9건 처리시간 0.017초

단열시트(뽁뽁이)의 종류 및 부착위치에 따른 창호의 단열성능 평가 (Thermal Performance Evaluation of the Window Systems with Air-bubble Sheets)

  • 황제;정아희;전병헌;안영철
    • 설비공학논문집
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    • 제27권9호
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    • pp.463-467
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    • 2015
  • The air-bubble sheet has been widely used to wrap fragile products for long-distance transportation. The further usage of the air-bubble sheet as a thermal-insulation material for the reduction of the thermal conductivities of window systems has occurred because of its low price, in addition to its thermal-conductivity properties. In this study, the thermal performances of a variety of commercial air-bubble sheets according to various applications were evaluated. The experiments were performed with single-glazed and double-glazed windows and three types of air-bubble sheets of different air volumes. U-values are used and were calculated for the determination of the thermal performances that are based on the KS F 2278. The maximum decrease of the U-value was measured as 1.092 when a sheet was attached onto the frame of single-glazed window. The square-like air-bubble sheet that contains the largest air volume shows the highest thermal-resistance value. Double layers of the air-bubble sheets show better performances than those of the single layers on both sides of the windows.

서중환경에서 표면피복 양생재 종류변화가 콘크리트의 초기 온도이력 및 균열발생에 미치는 영향에 관한 현장적용성 평가 (Field Application to Evaluate the Effect of Various Surface Covered Curing Blankets on Temperature Profile and Crack Occurrence of the Concrete under Hot Weather Condition)

  • 한민철;이상운
    • 대한건축학회논문집:구조계
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    • 제34권5호
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    • pp.27-34
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    • 2018
  • Concrete placed under hot weather condition suffers from larger slump loss, rapid moisture evaporation due to high air temperature. Proper measures for material, transportation and curing should be taken to prevent the quality deterioration of the concrete under hot weather condition. In Korea, Although the period of hot weather concrete in Korea occupies only 2 months, there are a lot of quality problems including plastic, drying shrinkage and cold joint. Therefore, the objective of this paper is to investigate and compare the temperature history and crack occurrence of the concrete, which was placed in the actual apartment house construction field under hot weather condition, in response to the application of surface covered curing blankets including PE film, single layer clear bubble sheet, white colored bubble sheet and aluminum metalized bubble sheet. Test results indicated that the application of white colored bubble sheet and aluminum metalized bubble sheet showed most favorable results in terms of reduction in temperature rise and crack occurrence as well as easiness in handling. But, due to light reflection by aluminum metalized bubble sheet, it is believed that white colored bubble sheet is preferable.

Development of Efficient Curing Sheet for Thermal Insulation Curing of Concrete in Cold Weather

  • Han, Cheon-Goo;Son, Myung-Sik;Choi, Hyun-Kyu
    • 한국건축시공학회지
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    • 제12권3호
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    • pp.291-298
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    • 2012
  • For cold weather concreting, frost damage at early age is generated in the concrete, and problems such as delaying of setting and hardening and lowering of strength manifestation emerge due to the low outside air temperature at the early stage of pouring, making the selection of an effective curing method critically important. Unfortunately, the tent sheet currently used as the curing film for heating insulation at work sites, not only has the problems of inferior permeability and extremely deteriorated airtightness, but a phenomenon of continuous fracturing is also generated along the direction of fabric of the material itself, presenting difficult circumstances for maintaining adequate curing temperature. The aim of this study was to develop an improved bubble sheet type curing film for heating insulation of cold weather concrete by combining mesh-tarpaulin, which has excellent tension properties, with bubble sheet, which offers superior insulation performance. The analysis showed that the improved curing film in which BBS1 is stacked to MT was a suitable replacement for curing films currently in use, as it has better permeability, tension property, and insulation performance than the T type film used at work sites today.

건조수축 저감형 유동화제 및 2 중 버블시트를 사용한 콘크리트의 현장적용 (Field Application of the Concrete with the Combination of Drying Shrinkage-Reducing Superplasticizer and Double Layer Bubble Sheet)

  • 한천구;오치현;신재경
    • 한국건축시공학회지
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    • 제7권1호
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    • pp.107-113
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    • 2007
  • This study investigates the filed application in Daebul Free Trade Zone applying both a flowing method using drying shrinkage-reducing superplasticizer(SRS) and an insulating curing method using double layer bubble sheet. Test results showed that fresh concrete satisfied target slump and air content. A structure adding SRS significantly decreased the total bleeding capacity and accelerated the setting time. As for the crack occurrence, the structure applying the flowing method and double bubble sheets simultaneously exhibited the most favorable crack endurance, while conventional concrete showed more than 1mm size of crack in overall. In addition, a structure applying the flowing concrete method partially presented the micro crack. For the area proportion of crack occurrence, the structure using the double bubble sheets indicated 9.8%, while others applying flowing concrete method was 28%, compared with that of conventional one. For the compressive strength of specimens, standard curing specimens indicated $3{\sim}33%$ higher value than that of specimens cured besides the field construction. The specimens containing SRS improved the strength of $2{\sim}6MPa$, which is $10{\sim}22%$ higher than that of conventional concrete.

수평 사각밀폐공간내의 전도열전달 기구에서 열모세관효과 (The Thermocapillary Effect on Pure Conduction Mechanism in a Closed Square Cavity)

  • 유재봉;안도원;유주식;엄용균
    • 대한기계학회논문집B
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    • 제29권11호
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    • pp.1209-1219
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    • 2005
  • In a closed square cavity filled with a liquid, a cooling horizontal upper wall and a heating lower wall, the flow isn't generated under the ground-based condition when Rayleigh number is lower than 1700. In this mechanism, Ra=1534, Temperature and velocity fields near an air-bubble in silicon-oil under a cooled upper wall were investigated. Temperature and velocity fields is visualized using the thermo-sensitive liquid-crystal and light sheet visualization technique. The quantitative analysis fer the temperature and the flow fields were carried out by applying the image processing technique to the original data. The symmetry shape of two vortexes near an air bubble was observed. As the bubble size increased, the size of vortex and the magnitude of velocity increased. In spite of elapsed time, a pair of vortexes was the unique and steady-state flow in a square cavity and wasn't induced to the other flow in the surround region.

Single Plane Illumination Microscopy - MicroPIV를 이용한 버블 유동에서 외부 자계 영향을 받는 자성입자 가시화 (Flow Visualization of Magnetic Particles under the external magnetic field in bubbly flow using Single Plane Illumination Microscopy - MicroPIV)

  • 이창제;조경래;이상엽
    • 한국가시화정보학회지
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    • 제19권1호
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    • pp.36-42
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    • 2021
  • This study measured the velocity of magnetic particles inside the power generation using external heat sources. Single Plane Illumination Microscopy (SPIM) was used to measure magnetic particles that are simultaneously affected by bubbly flow and magnetic field. It has the advantage of reducing errors due to particle superposition by illuminating the thin light sheet. The hydraulic diameter of the power generation is 3mm. Its surface is covered with a coil with a diameter of 0.3 mm. The average diameter of a magnetic particle is 200nm. The excitation and emission wavelengths are 530 and 650nm, respectively. In order to find out the flow characteristics, a total of four velocity fields were calculated in wide and narrow gap air bubbles, between the wall and the air bubble and just below the air bubble. Magnetic particles showed up to 8.59% velocity reduction in the wide gap between air bubbles due to external magnetic field.

건조수축 저감형 유동화제를 사용한 콘크리트의 현장적용 (Field Application of Concrete Using Drying Shrinkage-Reducing Superplasticizer)

  • 신재경;오치현;최진만;이성연;한민철;한천구
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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    • pp.13-16
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    • 2006
  • This study investigates filed application in Daebul Free Trade Zone of a flowing method using drying shrinkage-reducing superplasticizer(SRS) and an insulating curing method using double bubble sheets. Test showed that fresh concrete satisfied target slump and air content. A structure adding SRS significantly decreased the total bleeding capacity and accelerated the setting time. As for the crack occurrence, the structure applying the flowing method and double bubble sheets simultaneously exhibited the most favorable crack endurance, while conventional concrete showed more than 1mm size of crack in overall, and a structure applying only the flowing method partially presented micro crack. For the area proportion of crack occurrence, the structure using the double bubble sheets indicated 9.8%, while others applying flowing method was 28%, compared with 100% of conventional one. Standard curing specimens had about $3{\sim}6%$ higher compressive strength than that of specimens cured at adjacent field construction. In addition, using SRS improved about $5{\sim}7MPa$, than that of conventional concrete at 91 days elapse.

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수평원통 관에서 선회유동의 공기동 발생에 관한 실험적 연구 (An Experimental Study on the Generation of Air-core with Swirl Flow in a Horizontal Circular Tube)

  • 장태현
    • Journal of Advanced Marine Engineering and Technology
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    • 제28권6호
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    • pp.922-930
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    • 2004
  • An experimental investigation was performed to study on the generation of air bubble and air core with swirling flow in a horizontal cicular tube. To determine some characteristics of the flow, 2D PIV technique is employed for velocity measurement in water. The experimental rig is manufactured from an acryl tube. The test tube diameter of 80mm, and a length of 3000mm. The used algorithm is the gray leve cross-correlation method(Kimura et al. 1986). An Ar-ion laser is used and the light from the laser(500mW) passes through a probe to make two-dimensional light sheet. In order to make coded images of the tracer particles on one frame, an AOM(Acoustic-Optical Modulator) is used. The maximum axial velocities showed near the test tube wall at y/D =0.1 and y/D =0.9 along the test tube. The higher Reynolds number increase, the lower axial velocities are showed in the center of the test tube. The air bubbles are generated from Re =10,000 and developed into air core from the recirculating water pump rpm equal 30Hz. The pressure and temperature are measured across the test tube at X/D=3.33.

전력변환장치 캐비넷에서의 내부발열 개선을 위한 열유동 분석 및 유통안전성 향상을 위한 진동특성 분석 (Theoretical Heat Flow Analysis and Vibration Characteristics During Transportation of PCS(Power Conversion System) for Reliability)

  • 주민정;서상욱;오재영;정현모;박종민
    • 한국포장학회지
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    • 제28권2호
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    • pp.143-149
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    • 2022
  • PCS needs to freely switch AC and DC to connect the battery, external AC loads and renewable energy in both directions for energy efficiency. Whenever converting happens, power loss inevitably occurs. Minimization of the power loss to save electricity and convert it for usage is a very critical function in PCS. PCS plays an important role in the ESS(Energy Storage System) but the importance of stabilizing semiconductors on PCB(Printed Circuit Board) should be empathized with a risk of failure such as a fire explosion. In this study, the temperature variation inside PCS was reviewed by cooling fan on top of PCS, and the vibration characteristics of PCS were analyzed during truck transportation for reliability of the product. In most cases, a cooling fan is mounted to control the inner temperature at the upper part of the PCS and components generating the heat placed on the internal aluminum cooling plate to apply the primary cooling and the secondary cooling system with inlet fans for the external air. Results of CFD showed slightly lack of circulating capacity but simulated temperatures were durable for components. The resonance points of PCS were various due to the complexity of components. Although they were less than 40 Hz which mostly occurs breakage, it was analyzed that the vibration displacement in the resonance frequency band was very insufficient. As a result of random-vibration simulation, the lower part was analyzed as the stress-concentrated point but no breakage was shown. The steel sheet could be stable for now, but for long-term domestic transportation, structural coupling may occur due to accumulation of fatigue strength. After the test completed, output voltage of the product had lost so that extra packaging such as bubble wrap should be considered.