• Title/Summary/Keyword: surface to area ratio

Search Result 1,289, Processing Time 0.032 seconds

A Study on the Distribution Characteristic of Urban Surface Temperature and Urban Heat Island Effects (도시 지표면 온도분포 특성 및 열섬완화방안)

  • Do, Hu-Jo;Lee, Jung-Min;Ra, Jung-Hwa
    • Journal of Environmental Science International
    • /
    • v.16 no.5
    • /
    • pp.611-622
    • /
    • 2007
  • The purpose of this research was to three-criteria landuse-pattern, developing density, NDVI which were related to the heat island and find the distribution characteristic of urban surface temperature and urban heat island effects. The results of this study were as follows. According to the analysis of surface temperatures, the first grade was the outside-city like a mountain and its temperature was less than $12.18^{\circ}C$. The fifth grade was the downtown industrial area and its temperature was more than $23.54^{\circ}C$. It means Daegu-Metropolitan-City has the serious heat-island effect. the results of landuse pattern analysis, in case of fifth and forth grade, city area was occupied over 90% with residential, commercial and industrial areas, but in case of third grade, openspace was occupied over 70%. The results of developing density analysis, the temperature had high correlation with building ratio, road ratio, vegetation ratio and etc. To plan for the decrease of heat island effect needed the extension of green space, decrease of paving, but there was a limit to get the objective method for grade classification because of lacking in the basic data, the research of criteria will be accomplished continuously.

Enzymatic reaction model for the production of symmetrical lipid molecules using the response surface methodology

  • Hong, Joon-Sun;Shin, Jung-Ah;Lee, Ki-Teak
    • Korean Journal of Agricultural Science
    • /
    • v.45 no.2
    • /
    • pp.265-282
    • /
    • 2018
  • The purpose of this research was to produce symmetric (Saturated-Unsaturated-Saturated, SUS) triacylglycerol (TAG) using palm stearin fraction oil (PSFO) and high oleic sunflower oil (HOSO) as substrates to replace cocoa butter. PSFO was blended with HOSO (1 : 2 weight ratio), and $lipozyme^{(R)}$ TLIM (20 weight % of the substrate) was added. Interesterification was carried out in a shaking water bath at $55^{\circ}C$ at 220 rpm for 6 hours. The response surface methodology (RSM) through the central composite face design was employed to observe the optimized SUS-TAG. The independent factors were the reaction temperature ($X_1$: 65, 75 and $85^{\circ}C$), reaction time ($X_2$: 1, 3 and 5 hours) and ratio of TLIM ($X_3$: 10, 15 and 20 weight %). The dependent variables were $Y_1$ = Saturated-Unsaturated-Unsaturated (SUU, area %), $Y_2=SUS$ (area %), $Y_3$ = Saturated-Saturated-Unsaturated (SSU, area %), $Y_4$ = Unsaturated-Unsaturated-Unsaturated (UUU, area %), and $Y_5=sn-2$ unsaturated fatty acid (area %). The optimal conditions from the central composite face design minimized acyl migration while maximizing the presence of unsaturated fatty acid at the sn-2 position (73.43 area %). The optimal conditions were $X_1=65^{\circ}C$, $X_2=1hour$, and $X_3=20weight%$. As a result of the response surface analysis, the lack of fits was found as $Y_1=0.622$, $Y_2=0.438$, $Y_3=0.264$, $Y_4=0.526$, and $Y_5=0.215$, and their $R^2$ were 0.897, 0.944, 0.826, 0.857, and 0.867, respectively.

A Study for Energy Separation of Vortex Tube Using Air Supply System(II) - the effect of surface insulation - (공기공급 시스템에 적응되는 Vortex Tube의 에너지 분리특성에 관한 연구(II) -표면의 단열효과에 따른 영향-)

  • 방창훈;추홍록;유갑종
    • Journal of the Korean Society of Safety
    • /
    • v.14 no.1
    • /
    • pp.3-9
    • /
    • 1999
  • The vortex tube is a simple device which splits a compressed gas stream into a cold stream and a hot stream without any chemical reactions. Recently, vortex tube is widely used to local cooler of industrial equipments and air supply system. In this study, the insulation effect of surface on the efficiency of vortex tube was performed experimentally. The experiment is carried out for nozzle area ratio of 0.194, diameter ratio of cold end orifice of 0.6 and input pressure ranging from 0.2Mpa to 0.5Mpa. The purpose of this study is focused on the effect of surface insulation of vortex tube with the variation of cold air mass flow ratio. The results indicate that the temperature difference of cold and hot air are higher about 12% and 30% than that of not insulated vortex tube respectively. Furthermore, for the insulated vortex tube, the similarity relation for the prediction of cold end temperature as the function of cold air mass flow ratio and input pressure is obtained.

  • PDF

Estimate of pesticide residues in tomato varieties using ratio of surface area to weight (비표면적을 이용한 토마토의 과종별 농약 잔류량 예측)

  • Kwon, Hye-Young;Kim, Jin-Bae;Lee, Hee-Dong;Ihm, Yang-Bin;Kyung, Kee-Sung;Park, In-Hee;Choi, Jung
    • The Korean Journal of Pesticide Science
    • /
    • v.8 no.1
    • /
    • pp.30-37
    • /
    • 2004
  • This study estimated the correlation between surface area/weight ratios and pesticide residues in two varieties of tomato, mini tomato and tomato. The ratios of surface area/weight of mini tomato and tomato were $2.15cm^2g^{-1}$ and $1.00cm^2g^{-1}$ respectively. Pesticide residues were measured with four kinds of pesticide, chlorothalonil WP, chlorothalonil SC, oxadixyl WP, thiophanate-methyl WP. Ie residue amount of mini tomato was $1.4\sim2.4$ times higher than those in tomato regardless of the application date and frequency. The ratios of surface area/weight on tomato varieties played a key role for determining pesticide residue.

Performance characterization of liquid desiccant system with extended surface (확장표면을 적용한 액체식 제습시스템의 성능특성에 관한 연구)

  • Jang, Young-Soo;Song, Gwi-Eun;Lee, Dae-Young
    • Proceedings of the SAREK Conference
    • /
    • 2009.06a
    • /
    • pp.639-644
    • /
    • 2009
  • This study presents the new idea of liquid desiccant system with extended surface to reduce the system size. The extended surface is inserted between vertical cooling/heating tubes to increase the mass transfer area, and the liquid desiccant flows through the tube wall and the extended surface. Mathematical models for heat and mass transfer between liquid desiccant and air stream at tube wall and extended surface are provided. Dimensionless design parameters governing heat and mass transfer phenomena around the tube and the extended surface are identifier, and dimensionless operating parameters depicting system operating condition including flow rate ratio between dehumidification/regeneration processes, and mass flow rate ratio between air stream and liquid desiccant are explained. The effects of the parameters on system performance are summarized.

  • PDF

Comparison of Surface Characteristics and Adsorption Rate of Benzene Vapor According to Modifications of Activated Carbon (개질에 따른 활성탄의 표면특성과 Benzene 증기의 흡착속도 비교)

  • Lee, Song-Woo;Kam, Sang-Kyu;Lee, Min-Gyu
    • Journal of Environmental Science International
    • /
    • v.17 no.8
    • /
    • pp.919-924
    • /
    • 2008
  • The surface properties and adsorption rates of activated carbon modified with acid and base were compared. The distribution ratio of C and C-H on the surface of activated carbon were decreased by modification with acid and base, but the distribution ratio of C-O, C=O, and O=C-O were increased. Base modification damaged the surface of activated carbon more than acid modification, it caused the effect of 6 percent increments of surface area. Adsorption rate model was more suitable to second order equation than first order equation. Adsorption rate was controlled by adsorption in pore better than in surface.

A Study of Non-thermal Plasma Generation on a Photocatalytic Reactor Using a Ceramic Honeycomb Monolith Substrate (세라믹 벌집형 담체를 사용한 광촉매 반응기의 플라즈마 생성에 관한 연구)

  • 손건석;윤승원;고성혁;김대중;송재원;이귀영
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.10 no.2
    • /
    • pp.48-54
    • /
    • 2002
  • Since photocatalysts are activated by lights of UV wavelengths, plasma is alternatively used as a light source for a photocatalytic reactor. Light intensity generated by plasma is proportional to the surface area of catalytic material, and this, in many practical applications, is prescribed by the geometry of a plasma generator. Thus, it is crucial to increase the surface area far sufficient light intensity for photocatalytic reaction. For example, in a pack-bed type reactor, multitudes of beads are used as a substrate in order to increase the surface area. Honeycomb monolith type substrate, which has very good surface area to volume ratio, has been difficult to apply plasma as a light source due to the fact that light penetration depth through the honeycomb monolith was too short to cover sufficient area, thus resulting in poor intensity for photocatalytic reaction. In this study, nonthermal plasma generation through a photocatalytic reactor of honeycomb monolith substrate is investigated to lengthen this short penetration depth. The ceramic honeycomb monolith substrate used in this study has the same length as a three way catalyst used fur automotive applications, and it is shown that sufficient light intensity for photocatalytic reaction can also be obtained with honeycomb monolith type reactor.

Three-dimensional analysis of the cusp variation patterns of mandibular second premolar in Koreans (일부 한국인 하악 제2소구치 교두 변이 양상에 대한 3차원적 분석)

  • Nam, Shin-Eun
    • Journal of Technologic Dentistry
    • /
    • v.42 no.3
    • /
    • pp.220-227
    • /
    • 2020
  • Purpose: This study aims to investigate the cusp variation pattern of the Korean mandibular second premolar and to determine the difference in tooth diameter and surface area using a virtual three-dimensional model. Methods: Dental casts from 69 students were scanned as a virtual dental models with a three-dimensional dental model scanner. Tooth diameter, absolute and relative individual areas, total crown area, the number of lingual cusps and central groove pattern were analyzed using RapidForm 2004. The Mann-Whitney U-test and the Kruskal-Wallis test were performed to verify sexual dimorphism, the difference in tooth diameter and surface according to the cusp variation pattern (α=0.05). Results: There was no significant difference except in buccolingual diameter (p<0.05) and buccolingual diameter at the cervix (p<0.05). The relative surface area of the total clinical crown was 65.76% for the buccal half and 34.24% for the lingual half, with a ratio of 2:1. In the case of the presence of two lingual cusps, the ratio was 21.47% for the mesiolingual half and 14.12% for the distaolingual half, with a ratio of 3:2. The dominant central groove patterns of the second premolar were the H-pattern (42.0%), followed by the Y-pattern (37.7%), then the U-pattern (20.3%). The relative buccal half was largest in the U-pattern central groove and the relative lingual half was largest in the Y-pattern central groove (p<0.05). Conclusion: This study is significant in that it measured quantitative surface areas and the findings could be a meaningful reference to comprehend dental anatomy in Koreans.

A Study on the Analysis of Energy Consumption Patterns According to the Building Shapes with the Same Volume (동일 체적의 건물 형상에 따른 에너지 소비량 패턴에 대한 분석 연구)

  • Choi, Won-Ki;Kim, Heon-Joong;Suh, Seung-Jik
    • Journal of the Korean Solar Energy Society
    • /
    • v.27 no.2
    • /
    • pp.103-109
    • /
    • 2007
  • This study was focused on the establishment of a fundamental DB(database) that is available in the building design process, so we performed the simulation analysis about the energy consumption on the various same volume buildings. Because energy consumption in building is affected by the exterior surface area, the ratio of long/short length in surface and the adjacent internal surface area etc.. For these purpose, we assumed the unit module and made a constructable 16 model buildings which are composed of the 16 unit modules. Then we analyzed the simulation using the TRNSYS 16 and the Seoul weather data. In results, energy consumption in building is more reduced that in case of the smaller exterior surface area, the lower stories building and the larger adjacent surface area etc.. Further study is to be required the sensitivity analysis on the various weather conditions, building shapes and window area etc..

Bending behavior of squared cutout nanobeams incorporating surface stress effects

  • Eltaher, Mohamed A;Abdelrahman, Alaa A.
    • Steel and Composite Structures
    • /
    • v.36 no.2
    • /
    • pp.143-161
    • /
    • 2020
  • In nanosized structures as the surface area to the bulk volume ratio increases the classical continuum mechanics approaches fails to investigate the mechanical behavior of such structures. In perforated nanobeam structures, more decrease in the bulk volume is obtained due to perforation process thus nonclassical continuum approaches should be employed for reliable investigation of the mechanical behavior these structures. This article introduces an analytical methodology to investigate the size dependent, surface energy, and perforation impacts on the nonclassical bending behavior of regularly squared cutout nanobeam structures for the first time. To do this, geometrical model for both bulk and surface characteristics is developed for regularly squared perforated nanobeams. Based on the proposed geometrical model, the nonclassical Gurtin-Murdoch surface elasticity model is adopted and modified to incorporate the surface energy effects in perforated nanobeams. To investigate the effect of shear deformation associated with cutout process, both Euler-Bernoulli and Timoshenko beams theories are developed. Mathematical model for perforated nanobeam structure including surface energy effects are derived in comprehensive procedure and nonclassical boundary conditions are presented. Closed forms for the nonclassical bending and rotational displacements are derived for both theories considering all classical and nonclassical kinematics and kinetics boundary conditions. Additionally, both uniformly distributed and concentrated loads are considered. The developed methodology is verified and compared with the available results and an excellent agreement is noticed. Both classical and nonclassical bending profiles for both thin and thick perforated nanobeams are investigated. Numerical results are obtained to illustrate effects of beam filling ratio, the number of hole rows through the cross section, surface material characteristics, beam slenderness ratio as well as the boundary and loading conditions on the non-classical bending behavior of perforated nanobeams in the presence of surface effects. It is found that, the surface residual stress has more significant effect on the bending deflection compared with the corresponding effect of the surface elasticity, Es. The obtained results are supportive for the design, analysis and manufacturing of perforated nanobeams.