• 제목/요약/키워드: 수분 함수율

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Effects of Cross-Sectional Dimension and Moisture Profile of Small Specimens on Characteristics of Ultrasonic Wave Propagation (목재의 단면적과 수분경사가 초음파 전달 특성에 미치는 효과)

  • Kang, He-Yang;Lee, Kwan-Young
    • Journal of the Korean Wood Science and Technology
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    • v.28 no.2
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    • pp.19-24
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    • 2000
  • Effects of the cross-sectional dimension and moisture profile of wood specimens on the ultrasonic sound velocities of radiata pine heartwood and sapwood. Each moisture profile model specimen was made by composing five wood pieces with various moisture contents. As the cross-sectional dimensions decreased the ultrasonic velocities of both heartwood and sapwood decreased by 4~8%. In the ultrasonic signals transmitted through the specimens low frequency components more dominated than high frequency components as the dimension of cross section increased. The specimens with the same average MCs and different moisture profiles showed different ultrasonic velocities. By plotting the ultrasonic velocities against the average moisture contents of the inner three pieces of the moisture profile model specimens it was revealed that three distinct plot patterns existed.

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An Experimental Study on the Moisture Rate of Concrete and Spalling Resistance Measure for Impact of Concrete Moisture Rate on Spalling (콘크리트의 함수율과 폭렬발생에 미치는 영향에 따른 폭렬 방지 대책에 관한 연구)

  • Seo, Yoon-Jeong;Kim, Dong-Jun;Kwon, Young-Jin
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2010.04a
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    • pp.340-345
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    • 2010
  • 국내의 건축물은 강한 내력을 갖기 위해 사용되는 HSC빈도가 점진적 증가하고 있으며, HSC로 시공되어진 건축구조물에서의 화재 발생시 폭렬현상의 문제점이 대두되고 있다. 이에 국내외에서 폭렬현상에 대한 연구들이 진행되었고, 이를 통해 폭렬현상에 원인을 알게 되어 이를 토대로 폭렬 방지 방안을 세웠다. 이에 따라 폭렬현상의 원인 중 합수율이 있으며, 이는 콘크리트가 함유하고 있는 수분으로 고온시에 팽창하여 폭렬현상의 매커니즘이 형성된다. 또한 이러한 함수율이 폭렬 발생에 미치는 영향을 크게 하는 요인으로 탄산화와 양생방법이 있다. 우선 탄산화는 반응을 일으킬 경우, 생성물이 공극을 채워 고온시 팽창된 수분이 외부로 나가는 것을 방해하여 수증기압을 축적시키고, 양생방법에 따라 함수율이 달라지게 되어 고온시 팽창될 수분의 양을 결정하게 된다. 특히, 함수율에 의해 발생되는 폭렬을 방지하기 위해 고강도 콘크리트 내부의 수분을 제거하는 강제건조를 하거나 팽창된 수분이 빠져나갈 곳을 만들기 위해 고온에서 녹는 PP섬유를 사용해 공극을 만들어주는 방법이 있다. 따라서 본 연구는 HSC의 폭렬현상방지 대책을 위한 기초자료를 제시하고자 한다.

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Infiltration Measurement and Prediction of Soil Water Flow Redistribution (침투율 측정과 재분배시의 토양수분흐름의 추정)

  • 정상옥
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.29 no.2
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    • pp.74-81
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    • 1987
  • 지표에서 토양속으로 흐르는 물의 침수를을 동심원관형침수계를 사용하여 측정하였다. 내부관과 외부관을 비교함으로서 침투율 측정시 침투계 바깥쪽으로 흐르는 수평방향으로 흐름을 예상할수 있으며 서로 다른 초기함수조건에서 침투율을 측정, 비교함으로써 초기함수 상태의 침투율에 대한 영향을 고찰하였다. 측정치를 분석한 결과 예상한 대로 바깥쪽으로 흐르는 수평방향의 토양수분으로 인하여 외부관에서의 침투율이 내부관에서 보다 평균90% 컸으며, 또 초기 함수량이 작은 경우가 큰 경우보다 침투율이 켰다. 침수가 끝난 후 재분배시의 토양 수분 흐름은 수리지표를 검사함으로써 추정하였다.수평 및 수직방향의 수리지표는 다단 텐시오미터(multiple-depth tensiometer)를 사용하여 토양속의 공극수압을 측정하여 계산하였다 수리지표를 검사한 결과 재분배시 수평방향의 토양수분 흐름은 일정한 방향이 아니라 경우에 따라서 원관 침투계의 중심쪽으로 또는 바깥쪽으로 흘렀다. 이느 토양의 물리적 성질이 장소에 따라서 균일하지 않았음에 기인한 것이라 판단된다. 재분배시 수평 및 수직방향의 평균수리지표의 비율을 검사한 결과 시간이 경과할수록 비율이 감소 되었으며 또 깊이가 깊어질수록 감소하였다.이는 즉 시간이 지날수록 깊이가 깊어질수록 토양수분 흐름의 수평방향 성분이 감소한다는 것을 나타낸다.

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A Study on BTEX Removal Efficiency for Variation of Moistures by Microwave Process (유류오염토의 마이크로파 처리 시 토양의 함수율 변화에 따른 BTEX 제거특성에 관한 연구)

  • Ha, Sang-An;Yeom, Hae-Kyong;Yu, Mi-Yong
    • Journal of Soil and Groundwater Environment
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    • v.12 no.2
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    • pp.65-71
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    • 2007
  • This study has been focused on an application of microwave pre-treatment of soil contaminated with volatile organic chemicals, and BTEX(benzene, toluene, ethylene, xylene). Microwave experiments were carried out under different power conditions (2 kW, 4 kW) using different moisture contents and BTEX concentration. According to these results of this study, the most BTEX removal efficiency was with 20% moisture contents regardless of electric power. The result show that 2kW was determined to the optimum electric power at $10{\sim}30%$ moisture contents, but the optimum power was 4 kW at 50% of moisture content.

Effect of Dry Fog Injection on Waste Decomposition in an Aerobic Landfill (호기성매립지에서 드라이포그 주입에 의한 폐기물분해 촉진에 관한 연구)

  • Park, Jin-Kyu;Lee, Byung-Sun;Yoon, Seok-Pyo;Lee, Nam-Hoon
    • Journal of the Korea Organic Resources Recycling Association
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    • v.26 no.2
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    • pp.43-51
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    • 2018
  • The objective of this research was to assess the effect of moisture content and water injection method into the landfill on waste decomposition in an aerobic landfill. Firstly, respirometric experiments were performed in order to assess the effect of initial moisture content (20%, 30%, 40% and 50% respectively) on landfilled waste decomposition. The cumulative oxygen uptake and oxygen uptake rate were highly increased with the increase of initial moisture content. Secondly, lysimeter experiments showed that in comparison with the vertical injection method, dry fog system enhanced decomposition of organic wastes. Also, dry fog system provided uniform moisture distribution more than the vertical injection method within landfill.

Effects of Water Conditions and Rhizobium Inoculation on the Growth of Wisteria floribunda Seedlings in Slope Soils (절개지 토양에서 수분조건과 근류균 접종이 등나무 유묘생장에 미치는 영향)

  • Park, Chong-Min
    • Korean Journal of Environment and Ecology
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    • v.20 no.4
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    • pp.425-435
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    • 2006
  • The objectives of this research were to investigate the drought resistance as well as the growth of Wisteria floribunda seedlings with the soil water conditions. The seedlings for the research were grown in pots with strict water content control on a frame located outdoors. During the experiments, the soil water contents were adjusted to 5, 10, 20, 30, 40, 50, 60, and 70%. In addition, the effects of Rhizobium inoculation on the growth of seedlings were investigated. The experimental results are summarized as follows: 1. The seedlings in the pots with 5% soil water content withered to death due to the water stress. Withering or any distinct growth was not observed from the seedlings in the 10% soil water content. It can be inferred from these results that about 5% of soil water content is the wilting point of W. floribunda seedlings and about 10% is the critical soil water content of its growth in this experiment soils. Therefore, it seems that W. floribunda possesses a good drought resistance. 2. From the analyses of the main growth parameters such as stem elongation, diameter growth, leaf area growth and total dry weight, it was found that the seedling growth can be improved with increasing soil water contents. The relation between each growth parameter(Y) and the soil water contents(W) was well described by a quadratic equation, $Y=a+bW+cW^2$. 3. In soil water contents higher than 20%, the seedling growth(Y) was remarkable along with-its extended growing period, and related to the growing period(D) by a quadratic equation, $Y=a+bD+cD^2$. 4. The artificial inoculation of Rhizobiun promoted the growth of Wisteria floribunda seedlings. 5. Rhizobium was found to be more readily inoculated and to form more root nodules compared to seedlings grown in higher soil water contents.

Comparison of Germination Characteristics, and of Logistic and Weibull Functions to Predict Cumulative Germination of Grasses Under Osmotic Water Stress (수분장애시 목초 발아특성 및 누적 발아율 곡선 예측을 위한 Sigmoid 함수들 간의 비교)

  • 이석하;윤선강;백성범;박현구
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.11 no.4
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    • pp.209-214
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    • 1991
  • The germination of seeds is developmentally complex process requiring water uptake, which is regulated by both genotypic and environmental factors. The present study was undertaken to determine the difference in germination characteristics, and to compare the ability of the logistic and Weibull functions to describe the cumulative germination curve when two levels of osmotic potential(0, -5 bar) were put to seeds of alfalfa, tall fescue, orchardgrass, and Kentucky bluegrass. The effects of grass type, osmotic potential, and their interaction on the total germination and coefficient of germination velocity were significant(P<0.01). The Weibull equation for predicting percent cumulative germination curve of alfalfa had significantly lower residuals than the logistic equation regardless of osmotic potential(P<0.01), indicating that the Weibull equation was more efficient than the logistic equation to fit the data of the percent cumulative germination of alfalfa. The rate parameter from the logistic equation was decreased under water stress, whereas the scale and shape parameters were increased. There were significant differences in days to 20% germination estimated from the logistic and Weibull equations.

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Determination of Leaf Water Content by Beta Ray Transmission ($\beta$선에 의한 식물잎의 수분함량측정)

  • 이충열;원준연
    • Journal of Life Science
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    • v.8 no.5
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    • pp.492-496
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    • 1998
  • Intact measurement of leaf water content was attempted using the transmission of beta radiation. Prior to the experiments, two tested plants, rice and soybean, were grown in 1/5000a wagner pot. The moisure ratio of plant leaves were measured with the beta radiation transmission method using a G-M detector and $^{99}$ Tc as the beta ray sou-rce. Beta radiation transmission showed a tendancy to increase with the passage of time after leaf cutting. However, it showed a tendancy to decrease with water supply for the lack of water. A positive correlation was found between the leaf water content and beta radiation transmission. The mutiple regression analysis about leaf water content was obtained that the coefficient of partial regression for beta radiation transmission was much higher(rice; -0.863, soybean; -0.904) than that for specific leaf area(rice; 0.007, soybean: 0.004).

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Estimations of Moisture Profiles During Wood Drying Using an Unsteady-State Diffusion Model (II) - Experimental Verification for Red Oak - (비정상(非正常) 상태(狀態)의 확산(擴散)모델을 이용한 수분(水分) 경사(傾斜)의 예측(豫測) (II) - 실험적(實驗的) 검증(檢證) -)

  • Park, Jung-Hwan;Smith, William B.
    • Journal of the Korean Wood Science and Technology
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    • v.24 no.3
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    • pp.37-44
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    • 1996
  • 포수상태(包水狀態)의 루부라참나무(Quercus rubra) 시험편을 3가지 등온조건(等溫條件)에서 건조한 결과를 비정상상태(非正常狀態)의 확산(擴散)모델로 추정한 결과와 비교하였다. 표면이 충분히 젖은 상태인 건조초기에는 불안정(不安定)한 확산현상(擴散現象)이 관찰되었으나, 함수율(含水率)별 건조속도의 변이를 Fick's의 확산법칙과 비교할 때 유사한 형태를 보였다. 실험에서 얻은 건조조건별 건조곡선은 확산모델의 수치해석(數値解析) 결과와 거의 일치하였으며, 같은 평위함수율(平衛含水率) 조건에서 건조온도의 증가는 목재표면 보다 내부의 함수율 변화에 더 크게 영향하여 결과적으로 낮은 온도에서의 건조조건이 목재 내의 수분경사(水分傾斜)를 급하게 하는 것으로 밝혀졌다. 본 연구를 통해 목재 건조 중의 내부에 발생하는 수분경사를 추정하는데 비정상상태의 확산모델이 모든 함수율 범위에 걸쳐 유용하게 사용될 수 있음이 밝혀졌다.

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Effects of Moisture Content in Concrete on Diffuse Ultrasound (확산초음파의 콘크리트 함수율에 대한 의존성)

  • Ahn, Eunjong;Shin, Myoungsu
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.1
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    • pp.142-147
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    • 2020
  • This study investigates the effects of moisture content on diffuse ultrasound to be applied for the evaluation of micro-structural damage in concrete subjected to various environmental conditions. We monitored diffuse wave parameters for concrete samples in process of water saturation for 5 days. Dried samples were immersed in a water bath, and the change of moisture content in concrete were estimated by measuring the change of mass. For the diffuse wave analysis, a frequency range of 500 kHz, which represents a scattering regime of ultrasound in concrete, was selected. The test results reveal that the ultrasonic diffusivity slightly changed, and the ultrasonic dissipation significantly increased by approximately 120% in the process of water saturation. Therefore, the moisture content in concrete should be considered for the evaluation of micro-structural damage using diffuse wave techniques.