• Title/Summary/Keyword: soil moisture characteristics

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The Vegetation of Mt. Choksang (赤裳山의 植生)

  • Kim, Chang-Hwan;Seon-Hee Kang;Bong-Seop Kil
    • The Korean Journal of Ecology
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    • v.14 no.2
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    • pp.137-148
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    • 1991
  • The forest vegation and their structural characteristics in mt. chokang were investgated by phytosociological survey and ordination. It was classified five forests such as quercus tschonoskii community and fraxinus mandshurica community and this result has confirmed to coincide with community ciassification by polar ordination. Chang of diversity index was shown to decase, whereas dominance index, to increase according to chang high altitude. By soil moisture gradient, distribution pattern of fraxinus mandshurica, acer mono, carpinus cordata was in moist, but quercus serrata,˘quercus variabilis and mongolica, dry habitats.

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Study on Permeability Characteristics of Cement Mortar under Carbonation (탄산화 진행에 따른 시멘트 모르타르의 투수특성에 대한 연구)

  • Kwon, Seung-Jun;Song, Ha-Won;Park, Chan-Kyu
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.185-188
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    • 2006
  • During the carbonation process in concrete, the rate of carbonation depends on porosity and moisture content of the concrete. For underground reinforced concrete structures, the interior concrete surface may be exposed to carbonation and the exterior concrete surface exposed to moisture due to wet soil or underground water. In this study, the permeability coefficients in mortar partially carbonated is derived as a function of carbonation depth and porosity of mortar by applying the so-called micro pore structure formation model (MPSFM) which was developed for the modeling of early-aged concrete. The permeability coefficient obtained from the micro-level modeling of carbonated mortar is verified with the results of accelerated carbonation test and water penetration test in cement mortar.

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Effects of Soil Amendments on Survival Rate and Growth of Populus sibirica and Ulmus pumila Seedlings in a Semi-arid Region, Mongolia (몽골 반건조 지역에서 토양 개량이 백양나무와 비술나무 묘목의 활착 및 생장에 미치는 영향)

  • Jung, Yegi;Yoon, Tae Kyung;Han, Saerom;Kang, Hoduck;Yi, Myong-Jong;Son, Yowhan
    • Journal of Korean Society of Forest Science
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    • v.103 no.4
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    • pp.703-708
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    • 2014
  • This study was conducted to investigate effects of soil amendments on survival rate and growth of seedlings in a semi-arid region, Mongolia. 2-year-old Populus sibirica and Ulmus pumila seedlings were planted in alkaline sandy soils and treated with 2 levels of nitrogen, elemental sulfur, artificial moisture retention and converted loess. After 4 months, the seedling survival rate of both species decreased as the amount of nitrogen increased. Nitrogen has been generally known to increase seedling survival rate and growth by supplying nutrients, however, reduced survival rate in this study might be affected by consequential increase in soil osmotic pressure, which was caused by excessive nitrogen fertilization. The root collar diameter (RCD) growth of both species increased significantly by the treatment of converted loess, and only RCD growth of P. sibirica increased by the artificial moisture retention treatment. Although P. sibirica is drought-tolerant, it is in the group of Populus spp. which requires a high capacity of available water. Conversely, the elemental sulfur treatment showed no effect on survival rate and RCD growth for both species due to the low oxidation of sulfur in arid soils. The extended monitoring of seedling growth and soil characteristics is required to elucidate the long-term effects of soil amendments in the semi-arid region, and the further studies are also needed to examine the appropriate amount of fertilizers for both species.

Effect of Stress State and Moisture Condition on the Resilient Behavior of Subgrade Soils in Test Roads (응력상태와 함수비에 대한 시험도로 노상토의 회복탄성거동)

  • Park, Seong-Wan;Lee, Chi-Hun;Hwang, Kyu-Young
    • International Journal of Highway Engineering
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    • v.9 no.1 s.31
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    • pp.47-56
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    • 2007
  • Resilient characteristics on unbound pavement materials have been adopted for design and nonlinear analysis of pavement structure under traffic loadings. However, relatively few studies have been done on the nonlinear resilient behavior of unbound materials in Korea. In addition to that, only the limited information is available for estimating the resilient modulus values on subgrade soils. In this study, a laboratory resilient-deformation test under repeated loadings is performed in order to establish the nonlinear characteristics of unbound subgrade soils in test roads. Then, a constitutive model that correlates the resilient modulus with moisture and stress state from field condition is proposed respectively. The results from all procedures are presented in this paper. Finally, a comparative analysis is conducted to identify the proper models in the stress dependent modulus and seasonal moisture condition of subgrade soils in test roads respectively.

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Characteristics of compost produced in food waste processing facility (음식물류 폐기물 퇴비화시설에서 생산된 퇴비품질 특성)

  • Lee, Chang-hoon;Park, Seong-jin;Kim, Myeong-sook;Yun, Sun-gang;Ko, Byong-gu;Lee, Deog-bae;Kim, Sung-chul;Oh, Taek-Keun
    • Korean Journal of Agricultural Science
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    • v.42 no.3
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    • pp.177-181
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    • 2015
  • Food waste has been widely considered as a recycling resource to be applied to agricultural lands due to the effects of organic matter and nutrient for plant productivity. but the maturity and salt concentration in the compost produced from food waste processing facilities should be considered firstly, which was little information on compost quality produced from food waste treatment facility. In this study, we examined actual situation of food waste processing facility on the composting of food waste and evaluated the characteristics of composts produced from food waste processing facilities. The quality of composts was analyzed on the basis of the criteria of fertilizer processing manual. The 46% of food waste treatment facility registered composting produced actually the compost mixed with food waste or animal waste. The compost maturity and salt concentration as indicators of the quality of compost were not met 46.8% of composts collected from food waste processing facilities to the criteria of fertilizer processing manual. Also, 15.6%(moisture) were not satisfied with the criteria. In conclusion, the compost produced from food waste processing facilities is firstly required with better compost maturity and reduced salt concentration in order to use to agricultural lands as an amendment.

Studies on Selection of Adaptable Varieties in Paddy - Field of Ginseng Culture (인삼 논재배에 적응하는 품종 선발에 관한 연구)

  • Kang, Seung-Weon;Lee, Sung-Woo;Hyun, Dong-Yun;Yeon, Byeong-Yeol;Kim, Young-Chang;Kim, Young-Chul
    • Korean Journal of Medicinal Crop Science
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    • v.18 no.6
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    • pp.416-420
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    • 2010
  • Root yield and quality of ginseng cultured in paddy soil was low relatively compared with that of upland soil because of moisture injury in root during rainy season. Drainage class in soils generally divided into 6 classes, and it is possible to cultivate ginseng practically in imperfectly drainage class (IDC). This study carried out to select the varieties that is suitable for paddy soil, which is easy to be generated rusty-colored root and physiological-discolored leaf. Experiment plot arranged with the condition of soil humidity contents such as poorly drainage class (PDC) and imperfectly drainage class (IDC), and upland soil. Growth characteristics and root yield were investigated in four-year-old ginseng of varieties, Cheonpoong (CP), Yeonpoong (YP), Hwangsookjong (HS), and Jakyeongjong (JK). CP among four varieties showed the highest yield in IDC and CP was the lowest ratio in leaf discoloration and rusty-colored root. HS was followed by CP in the order of root yield, but it had the weakness that the ratio of rusty-colored root was high respectively.

A Study on the Compaction Characteristics of Crushed Rock-soil Mixture for Railway Subgrade (암버럭-토사 혼합성토재 철도노반의 다짐특성 연구)

  • Kim, Dae-Sang;Park, Seong-Yong;Song, Jong-Woo;Kim, Soo-Il;Song, Jae-Joon
    • Journal of the Korean Society for Railway
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    • v.12 no.2
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    • pp.183-189
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    • 2009
  • The track structure of Gyungbu High Speed Railway line from Daegu to Busan is concrete track. It has a very strict specification for residual settlement because of its rigid type structural characteristics. The residual settlement of it comes from the residual settlement of the subgrade and the ground. The residual settlement of railway subgrade composed of crushed rock and soil might be major parts of total residual settlement depending on the field compaction qualities. Therefore, it is a key to minimize the residual settlement of the subgrade for a successful concrete track construction. In this paper, total 31 large scale compaction tests were performed to understand the compaction behaviors of the crushed rock-soil mixture. The test specimens were constituted with soil, crushed shale and mudstone taken from two sites under construction. The compaction tests were performed with the variations of rock types, #4 sieve passing contents, maximum particle size, and moisture contents. The influence of those factors on maximum dry unit weights of crushed rock-soil mixture was evaluated.

Observation of Moisture Fluctuations in the Upper Canopy and the Ground Surface of Deogyusan-Flux (덕유산 flux관측소의 군락 상층부와 지표면에서의 수분이동 관측)

  • Kim, Yong-kuk;Lee, Bu-yong
    • Journal of Environmental Science International
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    • v.31 no.1
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    • pp.43-50
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    • 2022
  • In this paper, lysimeter was installed to analyze the moisture fluctuations on the surface of a forest. The weight of the soil was measured, and the moisture fluctuations were calculated through the difference in weight over time. The amount of dew condensation on the surface of the ground was about 2-7 mm. January experienced the most dew condensation (7.2 mm). It was found that about 43 mm of dew condensation was generated over one year. To analyze the characteristics of evapotranspiration in the forest, the evapotranspiration on the surface was measured by the lysimeter method and the evapotranspiration on the upper part of the canopy was measured by the eddy covariance method. These results were compared and analyzed. Until mid-October, the evapotranspiration of the forest was active, and the amount of evapotranspiration on the top of the canopy was higher than the amount on the surface. Thereafter, the amount of evapotranspiration on the top of the canopy decreased due to the lowering of temperature and net-radiation. The amount of evapotranspiration on the surface and above the canopy showed the same tendency.

Detection of flash drought using evaporative stress index in South Korea (증발스트레스지수를 활용한 국내 돌발가뭄 감지)

  • Lee, Hee-Jin;Nam, Won-Ho;Yoon, Dong-Hyun;Mark, D. Svoboda;Brian, D. Wardlow
    • Journal of Korea Water Resources Association
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    • v.54 no.8
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    • pp.577-587
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    • 2021
  • Drought is generally considered to be a natural disaster caused by accumulated water shortages over a long period of time, taking months or years and slowly occurring. However, climate change has led to rapid changes in weather and environmental factors that directly affect agriculture, and extreme weather conditions have led to an increase in the frequency of rapidly developing droughts within weeks to months. This phenomenon is defined as 'Flash Drought', which is caused by an increase in surface temperature over a relatively short period of time and abnormally low and rapidly decreasing soil moisture. The detection and analysis of flash drought is essential because it has a significant impact on agriculture and natural ecosystems, and its impacts are associated with agricultural drought impacts. In South Korea, there is no clear definition of flash drought, so the purpose of this study is to identify and analyze its characteristics. In this study, flash drought detection condition was presented based on the satellite-derived drought index Evaporative Stress Index (ESI) from 2014 to 2018. ESI is used as an early warning indicator for rapidly-occurring flash drought a short period of time due to its similar relationship with reduced soil moisture content, lack of precipitation, increased evaporative demand due to low humidity, high temperature, and strong winds. The flash droughts were analyzed using hydrometeorological characteristics by comparing Standardized Precipitation Index (SPI), soil moisture, maximum temperature, relative humidity, wind speed, and precipitation. The correlation was analyzed based on the 8 weeks prior to the occurrence of the flash drought, and in most cases, a high correlation of 0.8(-0.8) or higher(lower) was expressed for ESI and SPI, soil moisture, and maximum temperature.