• Title/Summary/Keyword: Total radiation flux

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A Calculation Method on Heat Flux from Ondol Floor Surface (온돌면(溫突面)의 방열량(放熱量) 산정방법(算定方法)에 관한 연구(硏究))

  • Sohn, Jang Yeul;Ahn, Byung Wook;Pang, Seung Ki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.1 no.2
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    • pp.173-181
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    • 1989
  • Until recently there was a lack of reliable performance data for the design and operation of Ondol heating systems. This paper presents a calculation method on heat flux from Ondol floor surface. Total heat flux from floor consists of radiation and convection component. In order to analyse the characteristics of both radiation and convection heat flux, each surface temperature is measured and several temperatures near each wall are measured vertically and horizontally in a practical Ondol heating space. Radiation heat flux is calculated and analysed by Gebhart's Absorption Factor Method with the consideration of instantaneous radiant exchanges. Convection heat output is derived from the vertical temperature profiles near floor. The vertical temperature profiles could be expressed by nonlinear regression equation models and convection coefficients could be estimated by the equations. As a result, radiation, convection and total heat flux are suggested by the expression of difference between floor surface and room air temperature.

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The Impact of Total Radiation Flux on Organic Materials under LED Lighting

  • Kim, Ji Won;Lee, Jin Hwan;Kim, Kyu Lin;Ryu, Jae Hyung;Kang, Dai Ill
    • Journal of Conservation Science
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    • v.36 no.4
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    • pp.236-243
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    • 2020
  • In this study, an accelerated aging experiment for fabric and paper was conducted using two light emitting diode(LED) sources with different wavelength characteristics, and the discoloration under each lighting type was examined. Hanji(Korean traditional paper) and related textiles showed more discoloration under blue LEDs, while the blue wool standard showed more discoloration under white LEDs. This, indicated that the deterioration varied depending on the sample color. The the effect of the light source on artifact deterioration was primarily related to the total radiation flux(expressed in mill watts), rather than the total luminous flux(expressed in lumens). In addition, the discoloration of the investigated artifacts was dependent on the color rendering of the lighting.

A Study about The Effect of Radiation on Particle-Seeding Hydrogen Flame (고체입자의 수소화염에 있어서의 열복사에 관한 연구)

  • Choi, Joon-Won;Baek, Seung-Wook;Kim, Jung-Ju;Kim, Han-Seok
    • 한국연소학회:학술대회논문집
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    • 2002.11a
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    • pp.129-139
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    • 2002
  • From the view of the environmental protection against the use of fossil fuels, a great of efforts have been exerted to find an alternative energy source. Hydrogen may become an alternative. However the product species of the hydrogen flame is only $H_2O$, which emits only non-luminous radiation so the radiation from it is much smaller than that for a hydrocarbon flame. In this study, the authors designed and fabricated a laboratory scale test furnace to study thermal characteristics of hydrogen-air diffusion flame. In addition, the effects of addition of reacting as well as non-reacting solid particles were experimentally investigated. Among the total heat flux to the wall, about 75% was occupied by radiation while 25 % by convection. When the aluminum oxide ($Al_2O_3$) particles were added, the radiative heat flux was reduced due to heat blockage effects. On the other hand, the total as well as the radiative heat flux was increased when the carbon particles were seeded, since the overall temperature increased. The effects of swirl and excess air ratio were also examined.

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The Effects of $CO_2$ on Heat Transfer from Hydrogen Oxygen-enriched Flame (이산화탄소가 수소 산소부화 화염의 열전달에 미치는 영향)

  • Lee, Chang-Yeop;Choi, Joon-Won;Baek, Seung-Wook
    • 한국연소학회:학술대회논문집
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    • 2003.05a
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    • pp.261-266
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    • 2003
  • An experimental study has been conducted to evaluate the effects of $CO_{2}$ on heat transfer from hydrogen oxygen-enriched flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which mounted on top of the furnace. Five composition conditions of oxidizer were chosen with replacing $N_{2}$ with $CO_{2}$. In a steady state, total and radiative heat flux rates from the flame to the wall of furnace has been measured using heat flux meters. Temperature distribution in furnace also has been checked. Increasing $CO_{2}$ ratio in the oxidizer, the dominant heat transfer mode was changed into convection from radiation. Temperature in the furnace decreased but total heat flux increased.

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Effects of CO2 on Heat Transfer from Oxygen-Enriched Hydrogen Flame (이산화탄소가 수소 산소부화 화염의 열전달에 미치는 영향)

  • Lee, Chang-Yeop;Choi, Joon-Won;Baek, Seung-Wook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.8 s.227
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    • pp.937-944
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    • 2004
  • An experimental study has been conducted to evaluate the effects of $CO_2$ on heat transfer from oxygen-enriched hydrogen flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which was mounted on top of the furnace. Five different oxidizer compositions were prepared by replacing $N_2$ with $CO_2$. In a steady state, the total as well as radiative heat flux from the flame to the wall of furnace have been measured using a heat flux meter. Temperature distribution in furnace also has been measured and compared. By increasing $CO_2$ proportion in the oxidizer, the convection played a more significant role rather than radiation. Overall temperature in the furnace was seen to be decreased, while the total heat flux has increased.

A Numerical Analysis of Characteristics of Combined Heat Transfer in Laminar Layer Along Cylinderical Periphery by P-N Method (P-N 근사법을 이용한 원관주위 층류 경계층내 조합 열전달 전달 특성 해석)

  • 이종원;이창수
    • Journal of Advanced Marine Engineering and Technology
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    • v.19 no.2
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    • pp.10-19
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    • 1995
  • Heat trnasfer for absorbing and emitting media in laminar layer along the cylinders has been analyzed. Governing equation are transformed to local nonsimilarity equations by the dimensional analysis. The effects of the Stark number, Prandtl number, Optical radius and wall emissivity are mainly investigated. For the formal solution a numerical integration is performed and the results are compared with those obtained by P-1 and P-3 approximation. The results show that boundary layers consist of conduction-convection-radiation layer near the wall and convection-radiation layer far from the wall. As the Stark number of wall emissivity increases the local radiative heat flux is increased. The Pradtl number or curvature variations do not affect the radiative heat flux from the wall, but The Prandtl number or wall emissivity variations affect the conduction heat flux. Consequently the total heat flux from the wall are affected by the Prandtl number or wall emissivity variation.

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An Experimental Study about The Effect of Solid Particle Seeding on Thermal Characteristics of Hydrogen Flame (고체 입자첨가가 수소화염의 열특성에 미치는 영향에 관한 실험적 연구)

  • Kim, Jung-Ju;Baek, Seung-Wook;Kim, Han-Seok;Choi, Joon-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.11
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    • pp.1503-1512
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    • 2002
  • From the view of the environmental protection against the use of fossil fuels, a great of efforts have been exerted to find an alternative energy source. Hydrogen may become an alternative However the product species of the hydrogen flame is only $H_2O$, which emits only non-luminous radiation so the radiation from it is much smaller than that for a hydrocarbon flame. In this study, the authors designed and fabricated a laboratory scale test furnace to study thermal characteristics of hydrogen-air diffusion flame. In addition. the effects of addition of reacting as welt as non-reacting solid particles were experimentally investigated. Among the total heat flux to the wall, about 75 % was occupied by radiation while 25% by convection. When the aluminum oxide (Al$_2$O$_3$) particles were added, the radiative heat flux was reduced due to heat blockage effects. On the other hand, the total as well as the radiative heat flux was increased when the carbon particles were seeded, since the overall temperature increased. The effects of swirl and excess air ratio were also examined.

Interrelationships between Sea Surface Temperatures and Clouds over the Tropical Oceans (열대 해양의 해수면온도와 구름의 상호관계)

  • 송봉근;김영섭;박경원
    • Proceedings of the KSRS Conference
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    • 2001.03a
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    • pp.92-97
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    • 2001
  • The intra-annual and interannual variations of total, high, middle, low clouds, and cloud forcing net solar radiation flux, cloud forcing net long-wave radiation flux, and SSTs over the tropical oceans are investigated with the use of ISCP D2, NCEP/NCAR Reanalysis for January 1983-December 1993. The intra-annual variation of total cloudiness is dominated by high and middle clouds in the western Pacific and central tropical oceans, the interannual variation of total cloudiness is also dominated by high and middle clouds in the central Pacific and Atlantic. The dominant intra-annual and interannual EOFs of total cloudiness have spatially coherent link with those SSTs. For the interannual EOFs, total cloudiness and SSTs are related to E1 nino-Southern Oscillation(ENSO). The second most important intra-annual EOFs of total cloudiness are related to Inter Tropical Convergence Zone(ITCZ). The third most important intra-annual EOFs show coherent relation in the western Pacific. The correlation analysis between cloud radiative effects and SSTs show spatially coherent relation over the tropical oceans even though cloud forcing cooling effect is much higher than heating effect.

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CRE ECPERIMENT OF KITSAT-1 (우리별 1호에서의 SPACE RADIATION 환경 조사)

  • 신영훈;민경욱;최영완;김성헌
    • Journal of Astronomy and Space Sciences
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    • v.11 no.1
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    • pp.131-145
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    • 1994
  • The Cosmic Ray Experiment (CRE) is one of the modules flown on board the KITSAT-1 satellite and consistes of two sub-systems: the Total Dose Experiment (TDE) and the Cosmic Particl Experiment(CPE). The purpose of CRE is to characterize the space radiation environment as encountered by an Earth-orbiting spacecraft. KITSAT-1 orbit is dominated by the inner Van Allen radiation belt. This region has a large population of high energy protons which contributes significantly to both long-term and transient radiation effects. The data shows that the inner Van Allen radiation belt is very stable and the solar activity influences the CPE, TDE data and SEU(Single Event Upset) rates. The result also shows that much larger high energy particle flux is recorded than the predictions of the CREME code.

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A Study on the Preparation and Hydrophilization of Polypropylene Microfiltration Membrane by Radiation-Induced Graft Polymerization (방사선 중합에 의한 폴리프로필렌 정밀여과막의 제조 및 친수화 거동에 관한 연구)

  • 황택성;이선아;황의환
    • Polymer(Korea)
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    • v.24 no.5
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    • pp.621-628
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    • 2000
  • Microporous polypropylene (PP) membranes have the high chemical and corrosion resistance, the good mechanical properties and the thermal stability under high temperatures, but its application is restricted within narrow limits due to hydrophobicity of membranes. In order to impart permanent hydrophilicity to the PP microfiltration membrane, the radiation-induced graft of 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AAc) containing hydrophilic functional group onto the membrane has been studied. The effect of graft conditions such as reaction time, total radiation dose, reaction temperatures, acid compositions on graft yield was investigated. Modified PP membranes were shown to cause an increase in the gas flux. Oil emulsion permeation flux of both original PP membrane and modified PP membrane was examined.

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