• Title, Summary, Keyword: Temperature Difference Ratio

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The relations between Waist-to-Hip Ratio(WHR) and the abdominal temperature (복부 지방율과 하복부 온도와의 관계)

  • Choi, Eun-Mi;Cho, Jung-Hoon;Jang, Jun-Bock;Lee, Kyung-Sub
    • Journal of Oriental Medical Thermology
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    • v.2 no.1
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    • pp.56-62
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    • 2003
  • Objectives : We intented to know the relations between Waist-to-Hip Ratio(WHR) and the abdominal temperature. Methods : Among the patients who visited the oriental gynecological department in Conmaul oriental medical hospital from 2002. 10. 10 to 2002. 11. 9. 130 women were selected for this study. We measured the abdominal temperature by D.I.T.I and Waist-to-Hip Ratio(WHR) by Inbody. Results and Conclusions 1. As WHR was higher, the abdominal temperature became lower. But there was no significant difference between WHR and the abdominal temperature of the abdominal obesity group and the non-abdominal obesity group in the each state. 2. There was significant difference in the abdominal temperature related with the abdominal obesity The abdominal temperature of the non-abdominal obesity group was higer than that of abdominal obesity group. 3. There was significant difference in the WHR according to the age, but no significant difference in the abdominal temperature according to the age. 4. This study showed that the abdominal temperature became lower among the 30-39 year-old women, as WHR was higher.

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DESIGN OF A LOW TEMPERATURE DIFFERENCE STIRLING ENGINE (저온도차 모형 스털링 엔진의 최대출력 설계조건)

  • Jung, P.S.;Won, M.Y.;Kim, S.Y.
    • Proceedings of the KSME Conference
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    • pp.420-423
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    • 2003
  • A low temperature difference model Stirling engine is a small Stirling engine running with several degree of temperature difference without power output. In this study, the design parameters to give maximum power are discussed. As results, the phase angle is about 100 degree, and compression ratio is 1.5% of the ratio of heat source temperatures at maximum power condition.

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Flow analysis of Buoyant Jets into Storage Tank through Variable Nozzles (각종 Nozzle을 통하여 저장조내로 유입되는 BUOYANT JETS의 유동해석)

  • Pak, Ee-Tong;Cho, Woon
    • Solar Energy
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    • v.9 no.2
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    • pp.42-50
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    • 1989
  • The Buoyant Jets were analysed experimentally changing flow rate (0.0291/s, 0.0371/s, 0.0451/s), ratio of nozzle tip area to throat area (aspect ratio ${\beta}$=0.4, 1.0, 1.9), and also the temperature difference (${\Delta}T=Ti-T{\infty}$) between the temperature of the inflow water into the storage tank ($1m{\times}1m{\times}3m$) and the mean temperature of the water in the storage tank were changed as $25^{\circ}C,\;35^{\circ}C$ and $45^{\circ}C$. The more aspect ratio decreased, the more the trajectories of Buoyant Jets center-line were decreased and not the more the trajectories of Buoyant Jets centerline were influenced by the increment of the difference of the temperature. The more aspect ratio decreased, the more the half widths and dilution ratio of Buoyant Jets were increased and not the more the half widths and dilution ratio of Buoyant Jets were influenced by the increment of the difference of the temperature. Fr number is the factor that can predict the flow pattern over the whole flow field. And yet for the consideration the near field of Buoyant Jets flow pattern is dominated by magnitude of momentum and buoyancy force.

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An Effect on the Solution Crystallization Temperature Difference and Cooling Capacity of the Absorption Chiller by a Solution Cooler in the Absorber (흡수기내 용액 냉각기가 흡수식 냉동기의 용액 결정화 온도차와 냉각 용량에 미치는 효과)

  • Chin, Sung-Min;Lee, Jae-Heon;Jurng, Jong-Soo
    • Proceedings of the KSME Conference
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    • pp.1518-1523
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    • 2003
  • The objective of the present work is to investigate an effect on the solution crystallization temperature difference and the cooling capacity of the absorption chiller by a solution cooler in the absorber. The cooling capacity of the absorption chiller can be higher, with the enhanced performance of the solution heat exchangers. But, because the solution crystallization temperature difference becomes smaller at the absorber inlet, the heat capacity of the solution heat exchangers might be limited by the danger of crystallization, which can cause the serious damages. In this paper, the heat capacity ratio of the solution cooler is defined as the ratio of the heat capacity of the solution cooler to that of the absorber. If it becomes larger in the additional type solution cooler, the solution crystallization temperature difference is augmented and the cooling capacity is also increased.

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Parametric studies on convection during the physical vapor transport of mercurous chloride ($Hg_2Cl_2$)

  • Kim, Geug-Tae;Lee, Kyong-Hwan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.14 no.6
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    • pp.281-289
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    • 2004
  • The temperature hump is found to be most efficient in suppressing parasitic nucleation. With the temperature humps, there are found to be observed in undersaturations along the transport path for convective-diffusive processes ranging from $D_{AB}$ = 0.0584 $\textrm{cm}^2$/s to 0.584 $\textrm{cm}^2$/s, axial positions from 0 to 7.5 cm. With decreasing Ar = 5 to 3.5, the temperature difference is increased because of the imposed nonlinear temperature profile but the rate is decreased. For 2 $\leq$ Ar $\leq$ 3.5, the rate is increased with the aspect ratio as well as the temperature difference. Such an occurrence of a critical aspect ratio is likely to be due to the effect of sidewall and much small temperature difference. The rate is decreased exponentially with the aspect ratio for 2 $\leq$ Ar $\leq$ 10. Also, the rate is exponentially decreased with partial pressure of component B, P for 1 $\leq$ P $\leq$ 100 Torr.$ B/ $\leq$ 100 Torr.

Miscibility and Thermomechanical Properties of Polyurethane/Polycarbonate and Polyurethane/Polyacrylonitrile Blends (Polyurethane/polycarbonate 및 polyurethane/polyacrylonitrile 블렌드의 상용성과 열기계적 성질)

  • 조재환;우경식;설경일;전병철
    • Textile Science and Engineering
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    • v.38 no.1
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    • pp.1-7
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    • 2001
  • Miscibility and thermomechanical properties of blends of polyurethane(PU) with either polycarbonate(PC) or polyacrylonitrile(PAN) were investigated in order to understand the shape memory characteristics of PU blends. The miscibility of blends was analyzed in terms of melting temperature depression and change in glass transition temperature(Tg). PU/PAN blends showed an existence of miscibility between PAN molecules and hard segments of PU, whereas no evidence for miscibility was shown between PAN molecules and soft segments of PU. However, it was found that PC molecules in PU/PC blends had some miscibility with both hard and soft segments of PU. Percent shape memory of PU/PC and PU/PAN blends, which was obtained from respectively. Percent shape fixity of blends increased with increasing PC and PAN contents in blends. The difference in shape momory and shape fixity between PU/PC and PU/PAN blends was not so large. However, judging from the relationship between shape memory and modulus ratio of blends, it was considered that shape recovery effect of PU/PC blend was larger than that of PU/PAN blend. The modulus ratio was defined as a ratio of tensile modulus measured at temperature of Tg-20($^{\circ}C$) to that at temperature of Tg+20($^{\circ}C$). Such a difference in thermomechanical property between two blends was likely to result from a difference in the miscibility of blends. That is, PU/PC blend formed uniformly continuous PU phases, whereas PU/PAN blend did not.

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Effect of aspect ratio on solutally buoyancy-driven convection in mercurous chloride $(Hg_2Cl_2)$ crystal growth processes

  • Kim, Geug-Tae;Lee, Kyoung-Hwan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.16 no.4
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    • pp.149-156
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    • 2006
  • For an aspect ratio (transport length-to-width) of 5, Pr = 2.89, Le = 0.018, Pe = 2.29, Cv = 1.11, $P_B$=40 Torr, solutally buoyancy-driven convection $(Gr_s=3.03{\times}10^5)$ due to the disparity in the molecular weights of the component A $(Hg_2Cl_2)$ and B (He) is stronger than thermally buoyancy-driven convection $(Cr_t=1.66{\times}10^4)$. The crystal growth rate is decreased exponentially for $2.5\;{\leq}\;Ar\;{\leq}\;5$, with (1) the linear temperature profile and a fixed temperature difference, (2) the imposed thermal profile, a fixed crystal region and varied temperature difference. This is related to the finding that the effects of side walls tend to stabilize convection in the growth reactor. But, with the imposed thermal profile, a fixed source region and varied temperature difference, the rate is increased far $2\;{\leq}\;Ar\;{\leq}\;3$, and remains nearly unchanged for $3\;{\leq}\;Ar\;{\leq}\;5$.

A Study on Thermal Comfortable Following the Thermal Environment Migration in Detached Housing Area (열환경 완화를 통한 주택지내 쾌적성 확보에 관한 연구)

  • Ryu, Ji-Won;Jung, Eung-Ho;Hoyano, Akira;Kim, Dae-Wuk
    • Journal of the Korean housing association
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    • v.24 no.1
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    • pp.51-59
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    • 2013
  • This study aims to improve the thermal comfort level of detached housing area by reducing the impact of thermal environment. The study focused on reducing surface temperature that is generated in buildings and adjacent spaces as a result of sensible heat load and presented a proposal on implementing planting method considering its outdoor condition and structure and composed materials. To perform the study, we utilized 3D-CAD to examine the outdoor condition and structure and composed materials that impact on surface temperature and conducted space design after reflecting climatic elements in simulations. The result is as follows. In reviewing temperature distribution of Heat Island Potential (HIP) of buildings and adjacent spaces, in case where green coverage ratio is increased, there was a $6^{\circ}C$ temperature difference and in regard to changes in the thermal environment in detached housing area, in case where rooftop planting, surface improvement, planting, and overall green coverage ratio is increased, there was a $10^{\circ}C$ temperature difference. In addition, there was difference in temperature in detached housing area following the changes in wind.

NATURAL CONVECTION AROUND A HEAT CONDUCTING AND GENERATING SOLID BODY INSIDE A SQUARE ENCLOSURE WITH DIFFERENT THERMAL BOUNDARIES

  • NITHYADEVI, NAGARAJAN;UMADEVI, PERIYASAMY
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.19 no.4
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    • pp.459-479
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    • 2015
  • Two-dimensional steady laminar natural convection around a heat conducting and generating solid body inside a square enclosure with different thermal boundaries is performed. The mathematical model is governed by the coupled equation of mass, momentum and energy. These equations are discretized by finite volume method with power-law scheme and solved numerically by SIMPLE algorithm with under-relaxation technique. Effect of Rayleigh number, temperature difference ratio of solid-fluid, aspect ratio of solid-enclosure and the thermal conductivity ratio of solid-fluid are investigated numerically for Pr = 0.7. The flow and heat transfer aspects are demonstrated in the form of streamlines and isotherms respectively.

Effects of Transition Temperature and Atomic Ratio on Glass Formation Tendency in the PbO-B$_2$O$_3$-TiO$_2$-BaO System (PbO-B$_2$O$_3$-TiO$_2$-BaO계의 유리화에 대한 전이온도 및 성분 원소비의 영향)

  • 이선우;심광보;오근호
    • Journal of the Korean Ceramic Society
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    • v.35 no.12
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    • pp.1274-1279
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    • 1998
  • The glass forming ability of the PbO-B2O3-TiO3-BaO system was investigated in relation to transitieon tem-peratures and the atomic ratio between constituents. Glass forming tendency was improved as the tem-peratures and the atomic ratio between constituents. Glass forming tendency was improved as the tem-perature differences between liquidus temperature and crystallization(or glass transition) temperature de-creased and the temperature difference between crystallization and glass transition temperature increases. The atomic ratio could be used as a criterion to deign glass systems. The interposition of B and Ba atoms between Pb and Ti atoms was one of important factors in glass formation.

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