• Title, Summary, Keyword: Moisture

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Experimental Research on the Comparison of Gravity Moisture Content and Relative Moisture Content in Calculating the Quantitative Percentage of Moisture Content (중량함수율 및 상대함수율 비교에 따른 정량적인 함수율 산정에 대한 실험적 연구)

  • Byun, Yong-Hyun;Ryu, Dong-Woo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.134-135
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    • 2016
  • This study aims to compare relative moisture content and gravity moisture content in calculating the rational percentage of moisture content. High-strength concrete, which is made of blast-furnace slag and silica fume, was used as the compound for this study, and the specimens were made into a saturated condition through the vacuum suction. According to the results of this study, all specimens were completely dried when they were under the temperature of 105℃ for more than 31 days. They were fully saturated after 72 hours through vacuum suction. In addition, relative moisture content responded more sensitively to moisture content than gravity moisture content did, so it can be concluded that relative moisture content is better in calculating the rational percentage of moisture content.

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Verification of the Validity of Moisture Transfer Model for Prediction of Indoor Moisture Generation Rate (실내 수증기 발생량 예측을 위한 습기 전달 모델의 검증에 관한 연구)

  • Lee, Dong-Kweon;Kim, Eui-Jong;Choi, Won-Ki;Suh, Seung-Jik
    • Journal of the Korean Solar Energy Society
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    • v.26 no.1
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    • pp.41-47
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    • 2006
  • Moisture in a building is one of the most important variables influencing building performance, human health, and comfort of indoor environment. However, there are still lacks in the knowledge of understanding the moisture problem well and controlling moisture. Accordingly, in order to provide the fundamental data to control moisture contents in the indoor air, this study was to predict moisture contents transferred through building envelopes and indoor moisture generation rate. Moisture transfer model was made by physical relations in each node, and the indoor moisture generation rate was gained by comparing the model with experimental analyses. From the study, we found out that moisture generation rate was critical and day-periodic, so that we predicted the indoor moisture content by substituting the constant value gained from the average in a day for the moisture generation rate.

The aging characteristics of composite insulating materials due to high-temperature and high-moisture (고온 다습하에서 복합절연재료의 열화특성)

  • 이종호;이규철;김순태;박홍태
    • Electrical & Electronic Materials
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    • v.7 no.1
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    • pp.15-24
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    • 1994
  • For increasing the insulating proper-ties and the reliability of composite materials due to environmental aging, the electrical and mechanical characteristics of moisture absortion specimens and moisture desorption specimens were investigated. After moisture absorption wt% and moisture desorption wt% increased with time, a state of saturation arrived subsequent to a constant time. Moisture absorption constants with the layers of glass fiber showed 0.0117 in 1 layer, 0.0123 in 2 layers and 0.0152 in 3 layers. Electrical and mechanical characteristics dropped significantly with moisture absorbing in composite materials. Although moisture dried completly at 70.deg. C, it is impossible to obtain the electrical and mechanical characteristics before moisture absorption. Many defaults by moisture in composite materials exist at interface between epoxy matrix and filler.

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Moisture Transfer and Velocity of Moisture Transmission by Wood in Steady State (정상상태(定常狀態)에 있어서 목재(木材)의 습기전달(濕氣傳達)과 투습속도(透濕速度))

  • Lee, Weon Hee
    • Current Research on Agriculture and Life Sciences
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    • v.10
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    • pp.41-47
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    • 1992
  • In general, the behavior of moisture transmission is estimated by vapor permeability or vapor transmission resistance, but its values obtained by experiments do not have great adaptability for practical situations because of changes in the experimental conditions. This fact is why only theoretical discussions have advanced. Thus, the fundamental study of the moisture transmission phenomenon has been treated lightly. Here, as the first step toward the basic research of moisture transmission, the amount of moisture transmission and the moisture distribution in specimens were investigated. The experiment was conducted in a steady state, and the moisture distribution was measured by slicing and weighing the specimens. From the examination of the vapor transmission resistance, the phenomenon of moisture transmission was dealt with devide the moisture transfer on the wood surface and moisture diffusion in wood. The following results were obtained. 1) The phenomenon of moisture transmission should be approached by its division into moisture transfer on the wood surface and moisture diffusion in the wood because the positive values of vapor transmission resistance exist in the extrapolation of thickness 0mm. 2) The distribution of moisture in wood can be illustrated by two straight lines intersecting at the point of nine percent moisture content : namely, diffusion coefficients have two constant values at moisture contents below and above nine percent. The shape of the distribution curve of moisture content is similar irrespective of the wood thickness. On the other hand, when the moisture contents on both sides was more than nine percent, the distribution of the moisture content could be illustrated by one straight lines. 3) The amount of moisture movement is determined by the moisture gradient in wood. 4) Coefficients of the moisture transfer depend on the thickness of the specimens.

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Environmentally Friendly Moisture-proof Paper with Superior Moisture Proof Property (I) -Properties of Moisture Proof Chemicals- (방습 효과가 우수한 환경친화적 방습지(제1보) -방습제의 특성-)

  • 유재국;조욱기;이명구
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.33 no.4
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    • pp.15-20
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    • 2001
  • The function of the moisture-proof paper is to prevent moisture from adsorbing into the packed goods. Water-vapor transmission rate of the moisture-proof paper should be less than 100g/$m^2$.24hr and the optimum rate would be less than 50g/$m^2$.24hr. In general the moisture-proof paper has been made by laminating polyethylene or polypropylene on top of the base paper. However this kind of moisture-proof paper has a problem in recycling so that it brings about environmental pollution. In general the moisture-proof paper has been made by laminating polyethylene or polypropylene on top of the base paper. However this kind of moisture-proof paper has a problem in recycling so that it brings about environmental pollution. The purpose of this paper was to make moisture-proof paper using the mixture of SB latex and wax emulsion which was recyclable and environmentally friendly. Water vapor transmission rate showed less than 50g/$m^2$.24hr in mixture ratio of 85:15, 87:13, 90:10. Especially the mixture ratio of 87:13 showed the most favorable water-vapor transmission rate. However, the moisture-proof layer was destroyed slightly by folding in packing. It has been observed that there was no close relationship between water-vapor transmission rate of the moisture-proof paper and grammage of the base paper, but the density of base paper had influenced on water vapor transmission rate. It was also observed that the moisture-proof paper could be recycled. The moisture-proof paper was similar to base paper in degree of the pulping, and there was no significant difference in dispersion between moisture-proof paper and base paper. Most of wax particles which caused the spots during drying process could be removed by flotation process. Tensile strength and tear strength of both moisture-proof paper and base paper after pulping were measured to examine the fiber bonding, and no significant difference in physical properties was observed.

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Estimation of High-Resolution Soil Moisture Using Sentinel-1A/B SAR and Soil Moisture Data Assimilation Scheme (Sentinel-1A/B SAR와 토양수분자료동화기법을 이용한 고해상도 토양수분 산정)

  • Kim, Sangwoo;Lee, Taehwa;Chun, Beomseok;Jung, Younghun;Jang, Won Seok;Sur, Chanyang;Shin, Yongchul
    • Journal of The Korean Society of Agricultural Engineers
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    • v.62 no.6
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    • pp.11-20
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    • 2020
  • We estimated the spatio-temporally distributed soil moisture using Sentinel-1A/B SAR (Synthetic Aperture Radar) sensor images and soil moisture data assimilation technique in South Korea. Soil moisture data assimilation technique can extract the hydraulic parameters of soils using observed soil moisture and GA (Genetic Algorithm). The SWAP (Soil Water Atmosphere Plant) model associated with a soil moisture assimilation technique simulates the soil moisture using the soil hydraulic parameters and meteorological data as input data. The soil moisture based on Sentinel-1A/B was validated and evaluated using the pearson correlation and RMSE (Root Mean Square Error) analysis between estimated soil moisture and TDR soil moisture. The soil moisture data assimilation technique derived the soil hydraulic parameters using Sentinel-1A/B based soil moisture images, ASOS (Automated Synoptic Observing System) weather data and TRMM (Tropical Rainfall Measuring Mission)/GPM (Global Precipitation Measurement) rainfall data. The derived soil hydrological parameters as the input data to SWAP were used to simulate the daily soil moisture values at the spatial domain from 2001 to 2018 using the TRMM/GPM satellite rainfall data. Overall, the simulated soil moisture estimates matched well with the TDR measurements and Sentinel-1A/B based soil moisture under various land surface conditions (bare soil, crop, forest, and urban).

Development of Correction Equation and Characteristics Evaluation for Moisture Meter of Microwave Resistance Type (고주파 저항방식 함수율계의 보정식 개발 및 특성평가)

  • Jeon, Hong-Young;Kang, Tae-Hwann;Han, Chung-Su
    • Journal of Biosystems Engineering
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    • v.35 no.3
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    • pp.175-181
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    • 2010
  • This study compared moisture content measured by moisture meter of microwave resistance type(MMMRT) and standard moisture content of paddy, and developed the correction equation using linear and curvilinear regression analysis, and to explore its significance test. The correction factor according to the range of moisture content was developed to improve the measurement precision of MMMRT. The results were as followings. The coefficients of determination of correction equation by linear and curvilinear regression analysis with comparing the MMMRT and standard moisture content were 0.946 and 0.968, respectively. The moisture content error of MMMRT and standard moisture content measured after the MMMRT were corrected by moisture content rate of every 5% using the correction equation by curvilinear regression analysis appeared with 0~0.5% and 0.9~1.8% respectively in the moisture content range of 15~20% and 20~25%.

Analysis of Soil Moisture Recession Characteristics in Conifer Forest (침엽수 산림에서의 토양수분 감쇄특성 분석)

  • Hong, Eun-Mi;Choi, Jin-Yong;Nam, Won-Ho;Yoo, Seung-Hwan
    • Journal of The Korean Society of Agricultural Engineers
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    • v.53 no.4
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    • pp.1-9
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    • 2011
  • Forest area covers 64 % of the national land of Korea and the forest plays a pivotal role in the hydrological process such as flood, drought, runoff, infiltration, evapotranspiration, etc. In this study, soil moisture monitoring for conifer forest in experimental forest of Seoul National University has been conducted using FDR (Frequency Domain Reflection) for 6 different soil layers, 10, 20, 30, 60, 90 and 120 cm during 2009~2010, and precipitation data was collected from nearby AWS (Automatic Weather Station). Soil moisture monitoring data were used to estimate soil moisture recession constant (SMRC) for analyzing soil moisture recession characteristics. From the results, empirical soil moisture recession equations were estimated and validated to determine the feasibility of the result, and soil moisture contents of measured and calculated showed a similar tendency from April to November. Thus, the results can be applied for soil moisture estimation and provided the basic knowledge in forest soil moisture consumption. Nevertheless, this approach demonstrated applicability limitations during winter and early spring season due to freezing and melting of snow and ice causing peculiar change of soil moisture contents.

Analysis of Soil Moisture Characteristics in Nut Pine Forest about Seasons and Soil Layers (잣나무림에서의 시기별 토층별 토양수분 특성분석)

  • Hong, Eun-Mi;Choi, Jin-Yong;Yoo, Seung-Hwan;Nam, Won-Ho
    • Journal of The Korean Society of Agricultural Engineers
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    • v.54 no.4
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    • pp.105-114
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    • 2012
  • Soil moisture plays a pivotal role in hydrological processes, especially in the forest which covers more than 64% of the national land. Soil moisture was monitored to analyze soil moisture change characteristics in terms of time and soil layers in this study. 2 Years soil moisture change data was obtained from the experimental nut pine forest and statistical analysis including auto-correlation and cross-corelation among soil moisture data from different soil layers was conducted. Using the monitored soil moisture data, a relationship between soil moisture change and precipitation was analyzed and seasonal soil moisture change characteristics were analyzed. From the result of inter-relationships among soil layers in terms of season and time lag, soil moisture change characteristics in the nut pine forest were upper soil layers were much sensitive than lowers, and seasonal variation if soil moisture for upper soil layers were bigger than lowers showing low correlation with precipitation in winter and spring due to freezing and snowfalls.

Simulation of Daily Soil Moisture Content and Reconstruction of Drought Events from the Early 20th Century in Seoul, Korea, using a Hydrological Simulation Model, BROOK

  • Kim, Eun-Shik
    • Journal of Ecology and Environment
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    • v.33 no.1
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    • pp.47-57
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    • 2010
  • To understand day-to-day fluctuations in soil moisture content in Seoul, I simulated daily soil moisture content from 1908 to 2009 using long-term climatic precipitation and temperature data collected at the Surface Synoptic Meteorological Station in Seoul for the last 98 years with a hydrological simulation model, BROOK. The output data set from the BROOK model allowed me to examine day-to-day fluctuations and the severity and duration of droughts in the Seoul area. Although the soil moisture content is highly dependent on the occurrence of precipitation, the pattern of changes in daily soil moisture content was clearly quite different from that of precipitation. Generally, there were several phases in the dynamics of daily soil moisture content. The period from mid-May to late June can be categorized as the initial period of decreasing soil moisture content. With the initiation of the monsoon season in late June, soil moisture content sharply increases until mid-July. From the termination of the rainy season in mid-July, daily soil moisture content decreases again. Highly stochastic events of typhoons from late June to October bring large amount of rain to the Korean peninsula, culminating in late August, and increase the soil moisture content again from late August to early September. From early September until early October, another sharp decrease in soil moisture content was observed. The period from early October to mid-May of the next year can be categorized as a recharging period when soil moisture content shows an increasing trend. It is interesting to note that no statistically significant increase in mean annual soil moisture content in Seoul, Korea was observed over the last 98 years. By simulating daily soil moisture content, I was also able to reconstruct drought phenomena to understand the severity and duration of droughts in Seoul area. During the period from 1908 to 2009, droughts in the years 1913, 1979, 1939, and 2006 were categorized as 'severe' and those in 1988 and 1982 were categorized as 'extreme'. This information provides ecologists with further potential to interpret natural phenomenon, including tree growth and the decline of tree species in Korea.