• Title/Summary/Keyword: Moist heat

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Multi-physics Model of Moisture Related Shrinkage on Lightweight and Normal Concrete (경량콘크리트 및 일반콘크리트의 수분관련 수축에 대한 다중물리모델)

  • Lee, Chang-Soo
    • Journal of the Korea Concrete Institute
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    • v.22 no.2
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    • pp.159-169
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    • 2010
  • A multiphysics model analysis including moisture transport, heat transfer and solid mechanics and experiments on the normal and light weight concrete were carried out in order to study the effect of preabsorbed water in the light weight aggregates on the drying and shrinkage characteristics of concrete. Consequently, with fixed water-cement ratio, loss of water content of normal and light weight concrete were compared and the results showed that the lightweight concrete lost less moist than the normal concrete in early age and long term which was by moist supply effect. Accordingly, shrinkage strain size and distribution of lightweight concrete were decreased, and shrinkage reducing effect was efficient in early age with water cement ratio 0.3 and in both early age, and long term with water cement ratio 0.5. The comparison of analysis results and exaperimental results indicate that characteristic values of moisture transport and the relation humidity and shrinkage strain from this study are resonable for application for other differential shrinkage analysis in lightweight concrete.

Air-conditioner cycle simulation using tube-by-tube method (관순법을 이용한 공조기 사이클 시뮬레이션)

  • Yoon, Baek;Park, Hyun-Yeon;Yoo, Guk-Chul;Kim, Yong-Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.4
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    • pp.499-510
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    • 1999
  • A computer program was developed for simulating performance(capacity, power consumption and etc.) of air-conditioners using compressor, fin-tube heat exchanger and capillary tube. The program consists of five modules, condenser, evaporator, compressor, capillary tube simulation modules and properties modules of refrigerant and moist air, The present program is focused on R22 only, however can be easily extended for other refrigerants such as R407C and R410A just by adding property modules. The compressor simulation module utilizes performance maps supplied by manufacturers-map-based model. The condenser and evaporator simulation modules are modeled using tube-by-tube method. Simulation results(capacity and power consumption) were compared with calorimeter test results of actual air-conditioners of window and split types, where more than 82% of the data lied within ${\pm}5$% of the predicted results.

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Biological Activities of Bamboo Leaf and Quality Characteristics of Buckwheat Cold Noodle Using Bamboo Leaf Powder as a Functional Ingredient (죽엽의 생리활성 및 죽엽분말 첨가 냉면의 제조)

  • Oh Hae Sook
    • Korean journal of food and cookery science
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    • v.20 no.5
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    • pp.498-504
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    • 2004
  • This study was conducted to determine the usefulness of bamboo leaf powder as a functional ingredient for buckwheat cold noodles. The anti oxidative and fibrinolytic activities of bamboo leaf powder were very high, and were further maintained or improved after strong heat treatment. We prepared buckwheat cold noodles using 0%, 3% or 5% of bamboo leaf powder. Only the cohesiveness of the noodle having 5% bamboo leaf powder was lower than that of the noodles contained 0% and 3% bamboo leaf powder. The L-, a- and b-values were significantly different between noodles which contained bamboo leaf powder and those which did not. Nevertheless, the amount of bamboo leaf powder didn't affect the color parameters of buckwheat cold noodles. According to sensory evaluation, the addition of bamboo leaf powder improved the score of color and texture of buckwheat cold noodles, but overall acceptance was not significantly affected. Cooked volume, cooking loss and turbidity of buckwheat cold noodle containing 5% bamboo leaf powder were lower than the others, indicating that adding 5% bamboo leaf powder prevented the softening of the noodles with moist heat. We concluded that the application of bamboo leaf for the production of buckwheat cold noodle will be a good way to intake the biologically active ingredients for good health.

Rheological Properties of Various Gelatinized Potato Starch Pastes (품종별 감자 전분 호화액의 리올로지 특성)

  • 정란희;김경애
    • Korean journal of food and cookery science
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    • v.7 no.3
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    • pp.1-6
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    • 1991
  • Potato starches are obtained from Irish Cobbler (the dry type), Shepody and superior (the intermediate type) and Dejima (the moist type). Rheological properties of heat-gelatinized potato starch paste were studied to elucidate difference of various potato starches. Heat-gelatinized 3 to 7% potato starch paste showed pseudo plasticity in yield stress. As starch paste concentration increased, the values of consistency index was increased. Relationship between logarithmic consistency index and concentration of potato starch paste was linear at 5% starch concentration. Concentration dependence of consistency index and yield stress of Shepody was highest. As measuring temperature increased, the value of consistency index was decreased. Irish Cobbler starch paste at $50^{\circ}C$, Shepody, Superior and Dejima starch paste at $60^{\circ}C$ showed linear relationships with different slopes. The activation energies of Shepody starch paste was 3.97㎉l/㏖.

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The Characteristics of a Bypass Air Conditioning System for Load Variation (부하변동에 대한 바이패스 공조시스템의 특성)

  • 김보철;신현준;김정엽
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.3
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    • pp.240-246
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    • 2002
  • Bypass air conditioning systems are divided into three types; an outdoor air bypass, a mixed air bypass and a return air bypass system. What makes the return air by pass system more effective is that it directs all of moist outdoor air through the cooling coil. The bypass air conditioning system can maintain indoor R.H (Relative Humidity) less than a conventional CAV (Constant Air Volume) air conditioning system by adjusting face and bypass dampers at part load. When a design sensible load (the ratio of sensible load to total sensible load) is 70 percent (at this time, RSHF (Room Sensible Heat Factor) . 0.7), indoor R.H was maintained 59 percent by the return air bypass system, but 65 percent by the conventional CAV air conditioning system (valve control system). The bypass air conditioning system can also improve IAQ (Indoor Air Quality) in many buildings where the number of air change is high.

Ecological study for The control of Green Contamination in Korean Show Caves

  • Kim, Byoung-Woo
    • Journal of the Speleological Society of Korea
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    • no.85
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    • pp.21-24
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    • 2008
  • The chlorophyta and thebryophyta are became extinct by the shutting out the light and low temperature in caves. Whenever they get the conditions, they grow again immediately. It is necessary to keep the illumination distance over 2m and use the indirect light. The effect of lamp light and temperature is very important in the control of green contamination but the water and moisture in caves are essential factors in green contamination in the show caves. It's better to get rid of green alae and mosses at early stage for the control of the increase of green contamination. They must be isolated completely without the dispersion with moist pieces of cloth or sponge. It is necessary to shut out the cave route periodically for the restoration of cave environments and ecosystem. It's better to use the lamp keeping illumination and restricting the ascension of heat for the control of green contamination.

Liquid Moisture Management and Surface Properties of the Fabric in Transient Condition (작업복 소재 직물의 액상 수분 전달 특성 및 표면특성 연구)

  • 유신정
    • Journal of the Korean Society of Clothing and Textiles
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    • v.25 no.1
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    • pp.61-70
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    • 2001
  • As important factors determining human sensorial comfort, liquid moisture management and surface properties of heat resistant workwear materials were examined. To figure out liquid moisture management properties of the test materials, absorption capacity, rate of absorption, and evaporation properties were assessed. A modified GATS(Gravimetric Absorbency Testing System) was used to measure the liquid moisture accumulation associated with the wicking of liquid moisture from sweating skin. The GATS procedure measures demand wettability of materials to take up liquid in a direction perpendicular to the fabric surface and it was modified to incorporate a special test cell and cover to assess absorption behavior in the presence of evaporation. Fabric stiffness, smoothness, number and the length of surface fibers, and an estimate of the contact area between the skin and fabric surface were measured to characterize the mechanical and surface properties of the test materials. Also an estimate of the force with which a fabric clings to moist skin was made using as wet-cling index.

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Surface Properties of Wood-Based Floorings for Under Heating Systems (Ondol) (온돌용 목질마루판의 표면물성)

  • 김종인;박종영;이병후;김현중
    • Journal of the Korea Furniture Society
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    • v.13 no.1
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    • pp.27-37
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    • 2002
  • This study was investigated with the surface properties such as physical and accelerated tests of wood-based floorings. In physical test, hardness and abrasion resistance values of laminate floorings were higher than those of others. The center line average surface roughness($R_a$) of imported laminate flooring was highest value($1.34{\mu}m$) and that of imported solid wood flooring was lowest value($0.62{\mu}m$). In cold resistance and moist heat resistance, no defects were found on the surface of all flooring (crack, blistering, peeling, and gloss loss etc.) after testing. Wet-cold-dry cycle test showed that plywood flooring appeared some cracks. In accelerated weathering test, color difference increased with increasing Xenon arc light irradiation

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Two Cases of Hemorrhoid Treated with SaAhm(舍岩) Acupuncture (舍岩鍼을 이용한 痔疾 치험 2例)

  • Chung, Sae-yeon;Kim, Yoon-bum
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.16 no.3
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    • pp.252-259
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    • 2003
  • Hemorrhoid generally refers to a prolapsed nodule in the anus, and major symptoms are swelling, bleeding, pain. itching, and rectal discharge. For severe conditions, that is stage Ⅲ & Ⅳ, hemorrhoidectomy is commonly performed by surgeons. Yet, many patients are afraid of postoperative recurrence, and complications such as pain, wound bleeding, urinary retention, and dyschezia are not avoidable. We treated two patients with Stage Ⅱ and Ⅲ. and both of the cases were diagnosed as the hemorrhoid due to "moist and heat of the large intestine". After a couple of times of treatment only with SaAhm acupuncture, the symptoms were improved to the degrees where no discomfort could be found in the daily living.

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Drawing of Twenty Kinds of State and Process on Psychrometric Chart (습공기선도 상에 20 종류의 상태 및 과정 값의 작도)

  • Kim, Deok-Jin
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.1201-1206
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    • 2008
  • Psychrometric chart displays graphically the thermophysical properties of moist air, so it is very conveniently used in air-conditioning and refrigeration. On general psychrometric chart, there are dry bulb temperature, web bulb temperature, absolute humidity ratio, relative humidity, specific enthalpy, specific volume, sensible heat factor, and enthalpy-humidity difference ratio. However, various state and process values besides aboves can be plotted on psychrometric chart. In this study, we developed the software drawing twenty kinds of lines, that is vapor pressure, mole fraction ratio of vapor, dew point temperature, degree of saturation, density, specific entropy, specific exergy, contact or bypass factor, uncomfort index, discomposition index, predicted mean vote index, predicted percent dissatisfied, and so on. We wish to this software is a help to design, analysis and education.

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