• Title/Summary/Keyword: 영하온도

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Experimental Study on the Sand and Gravel Embankment in Winter Season (사역재료의 동기성토에 관한 실험적연구)

  • 이형수
    • Water for future
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    • v.6 no.2
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    • pp.12-18
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    • 1973
  • This paper describes the study and test for sand and gravel embankment in winter season and also contribute to the development of construction method for the practical purposes. In order to make possible sand and gravel embankment in winter season, at first, the following eriteria on work are given under the normal weather condition: 1) The maximum diameter of material shall not exceed 30cm and sand content which is the ratio of the weight of sand to gravel shall not exceed 60% 2) Spreading depth shall not exceed 60cm each layer of material shall be compacted by over 6 times passing by thell ton smooth drum type of uibratory roller and the relative density shall exceed 60% In addition to the above conditions, the following criteria are given as winter season condition. 3) Sand contsnt shall not exceed 25%, and water content shall not exceed 4% 4) Dwing construction, the air temperature should be $70^{\circ}C$ below zero at minimum and $3^{\circ}C$ below zero onthe average and all the construction work should he continued without intersuptions. With above criteria, it is come to a conclusion that the conclusion that the construction of sand and gravel embankment in winter season will be done satisfactorily without any difficulty. On the basis of these criteria an actual construction was practiced and it was proved that those criteria are applicable to actual embankment of materials.

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Physico-Chemical Characteristics of Components and Their Effects on Freezing Point Depression of Garlic Bulbs (마늘의 성분조성(成分組成)과 내한성(耐寒性) 연구(硏究))

  • Park, Moo-Hyun;Kim, Jun-Pyong;Kwon, Dong-Jin
    • Korean Journal of Food Science and Technology
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    • v.20 no.2
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    • pp.205-212
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    • 1988
  • The effect of physicochemical characteristics on the freezing point depression of garlic bulb was studied to examine the reasons of cryoprotectivity in garlic bulb stored at subzero temperature. The composition of fresh garlic was characterized by having high soluble solids($40^{\circ}$ Brix; 90% on dry basis), comparing with $10^{\circ}$ Brix in case of other fruits and vegetables. Soluble solids were composed of 70% sugars, 20% protein, and 10% insoluble solids(including 3% of ash, 3% of crude fiber, and 4% of fat). The main component of sugars in garlic was fructosan with 1-29 degree of polymerization(D.P) and the fructosan of 4-5 D.P was over 50% of total fructosan. Freezing point of garlic bulb, which is a parameter of cryoprotectivity, was depressed as the concentration of soluble solids increased, and as the D.P value decreased in the same concentration of soluble solids.

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A Study on Freezing Characteristics of Pavements Using Data of Test Road (시험도로 자료를 이용한 포장의 동결특성 연구)

  • Jeong, Jin-Hoon;Bae, Sung-Ho;Kwon, Soon-Min
    • International Journal of Highway Engineering
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    • v.7 no.2 s.24
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    • pp.87-95
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    • 2005
  • To prevent the lowering of structural capability due to freezing and thawing in cold winter, numerous researches on frost heaving have been performed. As the result, the freezing index contour map of the Korea peninsula has been made for the design of the anti-freezing layer of pavements. However, the validity of the anti-freezing layer needs to be evaluated because systematic investigations on the variation of freezing depth with the thickness and material types of pavement layers and the configuration of the ground have been rarely performed. The freezing index of the Korea Highway Corporation test road site was calculated and the freezing depths of the concrete and asphalt pavements of the test road were investigated using the ambient and pavement temperature and water content. In addition, the investigated freezing depths were compared to the values estimated by existing freezing depth models. This is the preliminary study on the freezing-related data measured at the test road. The results with higher reliability will be produced by the long-term accumulation of the data and the analysis on it.

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Characteristic of Cabin Temperature According to Thermal Load Condition of Heat Pump for Electric Vehicle (전기자동차용 히트펌프의 열 부하 조건에 따른 캐빈온도 특성)

  • Park, Ji Soo;Han, Jae Young;Kim, Sung-Soo;Yu, Sang Seok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.2
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    • pp.85-91
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    • 2016
  • The Positive Temperature Coefficient (PTC) is used for cabin air heating of a battery electric vehicle, which is different from conventional vehicles. Since the PTC heater consumes a large quantity of power in a parasitic manner, many valuable studies have been reported in the field of alternative heat pumps. In this study, a model for an R134a heat pump taking into account the thermal environment of the cabin was developed for a MATLAB/SIMULINK(R) platform. Component and cabin models are validated with reference values. Results show that the heat pump is more competitive for parasitic power consumption over all ambient temperature conditions. Additionally, the method of waste heat recovery to overcome disadvantages when temperatures are below zero is applied to efficiently operate the heat pump.

Spatiotemporal Changes of Temperature and Humidity in Lentinula edodes Cultivation Sheds (표고시설재배사내 시·공간적인 온·습도변화)

  • Ryu, Sung Ryul;Koo, Chang Duck
    • Journal of Korean Society of Forest Science
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    • v.94 no.6
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    • pp.468-475
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    • 2005
  • To understand spatiotemporal changes of temperature and humidity in Lentimula edodes cultivation sheds, temperature, relative humidity were measured with HOBO H8 series sensors in log cultivation sheds and sawdust cultivation sheds. The results obtained from October in 2003 to October in 2004 were as follows; 1. Horizontal temperature changes were smaller at center of cultivation shed inside than comer of cultivation shed inside, while relative humidity changes were greater about 3% at center of cultivation shed inside than corner of cultivation shed inside. 2. Vertical temperature changes showed that the temperature was higher at above than at below when the temperature rises, while the temperature was lower at above than at below when the temperature falls. Thus close to soil surface temperature showed a little fluctuation. Vertical relative humidity changes showed that the relative humidity was lower at above than at below when the temperature rises, while the relative humidity was higher at above than at below when the temperature falls. After all temperature and relative humidity was the opposite in cultivation shed. 3. It's showed in log cultivation shed that the minimum temperature was a subzero temperature until the end of April, while the minimum temperature did above zero after the beginning of the May. Besides a winter was the greatest at daily temperature range during the four season, about $30^{\circ}C$. On the other hand the minimum relative humidity was less than 20% at April, May and June but more than 40% after May.

Effect on the Properties of Coated Paper by Drying Temperature and Curing Time (건조 온도 및 경화시간이 도공지 품질에 미치는 영향)

  • 박동국;최희연;김영하;이용규
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.34 no.4
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    • pp.16-21
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    • 2002
  • It was observed that drying temperature and curing time in the paper coating process as well as Tg of the latex used as a binder, greatly affected the properties of the coated paper such as roughness, paper and print gloss, K & N ink drop, and ink set-off. The higher drying temperature induced faster water evaporation and change in binding density, which caused an increase in paper roughness, ink gloss and ink set-off, but decrease in paper gloss and K & N ink drop. The increased curing time promoted latex filming and redistribution of the binder in coating layer. This increased pick strength and ink gloss, but decreased ink trapping. Finally, the higher Tg of the latex showed the wider changing range of these properties.

제품간장의 저장에 관한 연구(제1보) 온도 및 보존상태를 달리한 제품간장 저장 중의 일바성분의 변화 및 미생물의 동태

  • 이택수;주영하;신보규;유주현
    • Proceedings of the Korean Society for Applied Microbiology Conference
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    • 1975.07a
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    • pp.110.2-110
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    • 1975
  • 성분이 동일한 완제품간장을 3$^{\circ}C$, 15$^{\circ}C$, 5$^{\circ}C$로 각각 달리하여 밑봉과 개봉상태로 1년이상 보존하면서 경시적으로 성분의 변화및 미생물의 동태를 관찰하고 동시에 시판 간장중에 생육하는 미생물을 계측한 결과는 아래와 같다. (1) 총질소, 색도, 비중, 석염의 함량은 저장기간의 경과에 따라 증가 현상을 나타내었으며 고온(3$0^{\circ}C$, 15$^{\circ}C$), 개봉방치 상태에서는 저온(5$^{\circ}C$)밀봉방치 상태에 비하여 증가현상은 현저하였다.(중략)

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A study on the Relationship between Load Current and Temperature of 6.6 kV Cable Systems in Operation (운전중 6.6kV 케이블 시스템의 부하전류와 온도의 상관관계 연구)

  • Lee, Kwan-Woo;Hwang, Yung-Ha;Lee, Sang-Hun;Um, Keehong
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.1157-1158
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    • 2015
  • This work is to study the effect of load current on 6.6 kV power cables in operation. In order to figure out the relationship between load current and temperature of the power cables, we have developed measuring equipment for insulation resistance, temperature, and current tested on 9 cables at power station, Western Power Co. Ltd. The cables used in our test were in operation for the last 18 years. Our research over a year showed that the remaining lifetime of 8 cables was more than 20 years. The remaining lifetime of one cable was about 16 to 18 years.

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Quantitative Analysis of the Condensation Characteristics with Solar Radiations and Inner Temperature of the Tilted Box (일사량과 경사진 육면체 내부의 온도변화에 따른 응축특성에 관한 정량적 연구)

  • Lee, Cheun-Gi;Koh, Young-Ha;Kim, Byung-Chul
    • Journal of the Korean Solar Energy Society
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    • v.31 no.1
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    • pp.44-50
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    • 2011
  • The solar radiation, inner temperature of the tilted box and the amount of condensed water were measured to find the most effective purified water production system. The inner temperature of the tilted box was related with solar radiation that was affected by sunshine and cloud. With analyzing those relationships of the solar radiation, inner box temperature, the angle of tilted boxes and amounts of water condensation optimal collecting system area could be calculated.

Snowmelt Effect in Hancheon watershed, Jeju Island (제주 한천유역에 대한 시공간적인 융설 영향 평가)

  • Lee, Jeong Eun;Kim, Nam Won
    • Proceedings of the Korea Water Resources Association Conference
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    • 2015.05a
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    • pp.468-468
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    • 2015
  • 일반적으로 겨울철 강수는 기온에 따라 강우와 강설로 분류된다. 특히 기온이 임계온도보다 낮을 경우, 강수는 강설의 형태로 지표면에 도달하여 적설되어진다. 겨울철 산간에 적설된 눈은 봄철이 되어 기온이 상승함에 따라 융설(snowmelt)이 발생하여 유역의 유출에 기여한다. 이러한 융설은 기온이 영하로 내려가는 11-4월에 해당하는 갈수기에 유출량 등의 수문성분에 영향을 미치고 있다. 특히 제주유역의 경우, 고도에 따른 강수량, 기온의 차이가 매우 크므로 강설, 융설 현상의 시공간적인 발생에 대한 연구가 더욱 요구된다. 따라서, 본 연구에서는 제주유역의 강설, 융설 발생의 시공간적인 평가를 위해서 융설모의가 가능한 SWAT-K를 한천유역에 적용하여, 그 결과를 분석하였다. 융설모의 이론을 검토하고, 실제 대상유역에 융설을 고려하기 위한 매개변수를 설정하고, 월별, 소유역별로 강설, 융설 발생현황을 평가하였다.

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