• Title/Summary/Keyword: Various Thermal Environment

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Analysis of solar radiation and simulation of thermal environment in plastic greenhouse -Simulation of thermal environment in plastic greenhouse- (플라스틱 온실(温室)의 일사량(日射量) 분석(分析)과 열적(熱的) 환경(環境)의 시뮬레이션에 관(關)한 연구(硏究) -플라스틱 온실(温室)의 열적환경(熱的環境)의 시뮬레이션-)

  • Park, J.B.;Koh, H.K.
    • Journal of Biosystems Engineering
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    • v.12 no.2
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    • pp.16-27
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    • 1987
  • Greenhouse farming was introduced to the Korean farmers in the middle of 1950's and its area has been increased annually. The plastic greenhouse, which is covered with polyethylene or polyvinyl chloride film, has been rapidly spread in greenhouse farming since 1970. The greenhouse farming greatly contributed to the increase of farm household income and the improvement of crop productivity per unit area. Since the greenhouse farming is generally practiced during winter, from November to March, the thermal environment in the plastic greenhouse should be controlled in order to maintain favorable condition for plant growing. Main factors that influence the thermal environment in the plastic greenhouse are solar radiation, convective and radiative heat transfer among the thermal component of the greenhouse, and the use of heat source. The objective of this study was to develop a simulation model for thermal environment of the plastic greenhouse in order to determine the characteristics of heat flow and effects of various ambient environmental conditions upon thermal environments within the plastic greenhouse. The results obtained are summarized as follows: 1. Simulation model for thermal environment of the plastic greenhouse was developed, resulting in a good agreement between the experimental and predicted data. 2. Solar radiation being absorbed in the plant and soil during the daytime was 75 percent of the total solar radiation and the remainder was absorbed in the plastic cover. 3. About 83 percent of the total heat loss was due to convective and radiative heat transfer through the plastic cover. Air ventilation heat loss was 5 to 6 percent of total heat loss during the daytime and 16 to 17 percent during the night. 4. The effectiveness of thermal curtain for the plastic greenhouse at night was significantly increased by the increase of the inside air temperature of the greenhouse due to the supplementary heat. 5. When the temperature difference between the inside and outside of the greenhouse was small, the variation of ambient wind velocity did not greatly affect on the inside air temperature. 6. The more solar radiation in the plastic greenhouse was, the higher the inside air temperature. Because of low heat storage capacity of the plant and soil inside the greenhouse and a relatively high convective heat loss through the plastic cover, the increase of solar radiation during the daytime could not reduce the supplymentary heat requirement for the greenhouse during the night.

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Decomposition of Acetonitrile Using a Planar Type Dielectric Barrier Discharge Reactor Packed with Adsorption and Catalyst Materials (평판형 유전체 장벽 방전 반응기에서 충진물질에 따른 아세토나이트릴의 분해 특성)

  • 김관태;송영훈;김석준
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.2
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    • pp.157-165
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    • 2003
  • A combined process of non-thermal plasma and catalytic technique has been investigated to treat $CH_3$CN gas in the atmosphere. A planar type dielectric barrier discharge (DBD) reactor has been used to generate the non-thermal plasma that produces various chemically active species, such as O, N, OH, $O_3$, ion, electrons, etc. Several different types of the beads. which are Molecular Sieve (MS) 5A, MS 13X, Pt/alumina beads, are packed into the DBD reactor, and have been tested to characterize the effects of adsorption and catalytic process on treating the $CH_3$CN gas in the DBD reactor. The test results showed that the operating power consumption and the amounts of the by-products of the non-thermal plasma process can be reduced by the assistance of the adsorption and catalytic process.

Analysis of the Thermal Environment and Natural Ventilation for the Energy Performance Evaluation of the Double Skin System during the Summer (이중외피 시스템의 에너지성능평가를 위한 하절기 열환경 및 자연환기 분석)

  • Eom, Jung-Won;Cho, Soo;Huh, Jung-Ho
    • Journal of the Korean Solar Energy Society
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    • v.22 no.4
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    • pp.68-76
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    • 2002
  • This paper discusses thermal and ventilation performance which might be caused by the adoption of one of specific building facade techniques, Double Skin System(DSS). One building with a prototypical DSS was selected and systematically investigated through field monitoring and computer simulation techniques. A network model of ventilation was successfully made using COMIS to evaluate ventilation performance of the system which can hardly be done by field measurements. Various operating conditions of air conditioning on/off and window opening were implemented in this type of building. Through the appropriate operation of the DSS in summer, simulation-based and experimental results implicate that it can lead to cooling energy savings.

Electrochemical Characteristics of Arc Thermal Sprayed Inconel 625 Coating on SS400 Steel in Seawater (Inconel 625로 아크 용사코팅된 SS400강의 해수 내 전기화학적 특성)

  • Park, Il-Cho;Kim, Seong-Jong
    • Journal of the Korean institute of surface engineering
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    • v.49 no.2
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    • pp.172-177
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    • 2016
  • In this paper, various electrochemical experiments were conducted in seawater solution to evaluate corrosion damage behavior of arc thermal sprayed Inconel 625 coating on SS400 steel in marine environment. As a result, corrosion damages of thermal sprayed Inconel 625 coating preferentially occurred at the defect area, and they were observed as a form of pitting corrosion in the galvanostatic experiments. In Tafel analysis, corrosion current density of Inconel 625 coating was relatively high due to influence of interconnected pores and Cr oxides in the thermal spray coating layer. On the other hand, the result of the potential measurement, thermal sprayed Inconel 625 coating should need the post-treatment which can compensate the defects like pores and cracks because Inconel 625 coating presented a higher potential of about 290 mV than that of the SS400 steel.

Stability characteristic of bi-directional FG nano cylindrical imperfect composite: Improving the performance of sports bikes using carbon nanotubes

  • Chaobing Yan;Tong Zhang;Ting Zheng;Tayebeh Mahmoudi
    • Steel and Composite Structures
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    • v.50 no.4
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    • pp.459-474
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    • 2024
  • Classical and first-order nonlocal beam theory are employed in this study to assess the thermal buckling performance of a small-scale conical, cylindrical beam. The beam is constructed from functionally graded (FG) porosity-dependent material and operates under the thermal conditions of the environment. Imperfections within the non-uniform beam vary along both the radius and length direction, with continuous changes in thickness throughout its length. The resulting structure is functionally graded in both radial and axial directions, forming a bi-directional configuration. Utilizing the energy method, governing equations are derived to analyze the thermal stability and buckling characteristics of a nanobeam across different beam theories. Subsequently, the extracted partial differential equations (PDE) are numerically solved using the generalized differential quadratic method (GDQM), providing a comprehensive exploration of the thermal behavior of the system. The detailed discussion of the produced results is based on various applied effective parameters, with a focus on the potential application of nanotubes in enhancing sports bikes performance.

Thermal Environment Characteristics of Permeable Block Pavements for Landscape Construction (조경용 투수성 블록 포장의 열환경 특성)

  • Han Seung-Ho;Ryu Nam-Hyong;Kang Jin-Hyoung
    • Journal of the Korean Institute of Landscape Architecture
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    • v.34 no.2 s.115
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    • pp.18-25
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    • 2006
  • This study aims to measure and to analyze the thermal environment characteristics of the various permeable pavement materials such as grass pavement (GREEN BLOCK PARK), stone and grass pavement (GREEN BLOCK STEP), stone pavement (GREEN BLOCK MOSAIC) and wood pavement (WOOD BLOCK) under the summer outdoor environment. The thermal environment characteristics measured in the study includes the changes of surface temperature during the day, changes of the temperature on each pavement layer, and long and short wave radiation of each pavement surface. The experimental condition is based on the data on the hottest temperature (August 5, 2005, $34.0^{\circ}C$) of the you. Some of main findings are: 1) The heat environment was worse on the wood pavements than on the stone pavement. This is mainly due to the low albedo of the wood pavements (0.37) while the albedo value of stone pavements is 0.41. Small heat capacity of the wood pavements also contributes to this difference. 2) The heat environment was worse on the stone pavements than on the turf pavements. This was mainly due to the evapotranspiration of the plant growth layer of the turf pavements. 3) The peak surface temperature was the highest on the wood pavements ($56.1^{\circ}C$). The peak surface temperatures on the stone pavements, the stone-grass pavements and the grass pavements were $43.1^{\circ}C,\;40.1^{\circ}C\;and\;37.9^{\circ}C$, respectively. 4) To improve the thermal environments in the urban area, it is recommended to raise the albedo of the pavements by brightening the surface color of the pavement materials. Further studies on the pavement materials and the construction methods which can enhance the continuous evapotranspiration from the pavements surface are needed.

Women's Comfort Temperature Range and Dynamic Temperature Change for Maintaining Thermal Comfort in Low Temperature Environment (저온환경에서 여성 온열쾌적성 유지를 위한 쾌적온도범위 및 동적 온도변화 연구)

  • Kim, Soyoung;Lee, Okkyung;Lee, Heeran
    • Fashion & Textile Research Journal
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    • v.22 no.6
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    • pp.853-861
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    • 2020
  • Various types of clothing are being developed to boost thermal comfort during cold winters along with research on change of body temperature when heating is applied. There is a noticeable behavioral difference by gender when using heating panels in a cold environment; however, research on women has been insufficient. This study find a temperature range that provides sustainable thermal comfort in a low temperature environment by observing temperature and change of temperature when subjects are classified according to physical activities or cold sensitivities. For the study results, 8 women in their 20s were subjected to experiment in a low temperature environment for 75 minutes (sitting position: 30 min., running: 15 min., and sitting position: 30 min.). Subjects were asked to turn on/off the heating panel freely to analyze the range of comfortable temperature and clothing microclimate; in addition, skin temperature and heating panel temperature were measured and analyzed at 9 points. As a result, temperature at which subjects turn on and off the heating panel indicated a statistically meaningful difference between the cold sensitivity group depending on exercise or non-exercise. The range of comfortable abdomen temperature was wider than the lower back and was significantly reduced when the subject was running. The range of comfortable temperature was also largest for the heating panel temperature, microclimate, and skin temperature in suggesting that adequate adjustment will be required depending on the surrounding environment or movement of the wearer.

A Study on the Modeling Methods of Tower Type Apartment House (탑상형 공동주택의 모델링 방법론에 관한 연구)

  • Lee, Jae-Hyuk;Yoon, Sung-Hoon;Choi, Won-Ki
    • Journal of the Korean Solar Energy Society
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    • v.30 no.3
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    • pp.39-46
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    • 2010
  • This study is focused on the effect of thermal load according to the various plan types in tower-type apartment in Korea. So, we chose the '』' type model in order to analyze the shading effect of the plan type. The main results are as follows. In chosen model, cooling energy demands are more sensitive than heating ones when is compared with the two methods. And there are about 10% deviations between new and conventional method. Because new method considers more detailed than conventional one about the building geometries. We also found that this building type affects to the about 3 floors from the top and it doesn't affect to the thermal load in lower floors. From these facts, we suggest new modeling method to the similar researches that will be analyzed the thermal load on the tower type apartment in Korea. Also there is no difference of the thermal load in each azimuth between simple and detailed modeling method. Consequently, we judge that this new method considered the shading effect will be used a lot to the similar analysis in tower type apartment in Korea.

Evaluation of Methodology for the Measurement of VOCs in the Air by Adsorbent Sampling and Thermal Desorption with GC Analysis (흡착포집 및 열탈착/GC 분석에 의한 공기 중 휘발성 유기화합물의 측정방법론 평가)

  • 백성옥;황승만;박상곤;전선주;김병주;허귀석
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.2
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    • pp.121-138
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    • 1999
  • This study was carried out to evaluate the performance of a sampling and analytical methodology for the measurement of selected volatile organic compounds (VOCs) in the ambient air. VOCs were determined by the adsorbent tube sampling and automatic thermal desorption coupled with GC/FID and GC/MSD analysis. Target analytes were aromatic VOCs, including BTEX, 1,3,5-and 1,2,4,-trimethylbenzenes(TMBs), and naphthalene. The methodology was investigatedwith a wide range of performance criteria such as repeatability, linearity, lower detection limits, collection efficiency, thermal conditioning, breakthrough volume and calibration methods using internal and external standards. standards. Stability of samples collected on adsorbent tubes during storage was also investigated. In addition, the sampling and analytical method developed during this study was applied to real samples duplicately collected in various indoor and outdoor environments. Precisions for the duplicate samples and distributed volume samples appeared to be well comparable with the performance criteria recommended by USEPA TO-17. The audit accuracy was estimated by inter-lab comparison of both duplicate samples and standard materials between the two independent labs. The overall precision and accuracy of the method were estimated to be within 30% for major aromatic VOCs such as BTEX. This study demonstrated that the adsorbent sampling and thermal desorption method can be reliably applied for the measurement of BTEX in ppb levels frequently occurred in common indoor and ambient environments.

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The Study on Thermal Performance Evaluation of Building Envelope with VIPs

  • Jeon, Wan-Pyo;Kwon, Gyeong-Jin;Kim, Jin-Hee;Kim, Jun-Tae
    • KIEAE Journal
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    • v.16 no.1
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    • pp.5-10
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    • 2016
  • Purpose: The energy consumption in buildings has continuously increased in some countries and it reaches almost 25% of the total energy use in korea. Therefore there are various efforts to minimize energy consumption in buildings, and the regulations on building envelope insulation have been tightened up gradually. To satisfy the building regulation, the use of vacuum insulation panels(VIPs) is increasing. VIP is a high performance insulation materials, so that it can be thinner than conventional insulation material. When VIP is applied in a building, it may cause thermal bridge, which occurs due to very low thermal conductivity compared to other building materials and the envelope of VIPs. Method: This study designed the capsulized VIPs using conventional insulation for reduction of the thermal bridge. Then designed VIPs were applied to a wall. The linear thermal transmittance and the effective thermal conductivity were analyzed by HEAT2 simulation program for two dimensional steady-state heat transfer. The result compared with a wall with non-capsulized VIPs. Result: It analyzed that the wall with capsulized VIPs had lower linear thermal transmittance and reduced the difference of the effective thermal transmittance with one dimensional thermal transmittance compared to that of the wall with non-capsulized VIPs.