• Title, Summary, Keyword: vegetation loss

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Measurement and Modeling of Vegetation Loss in the Frequency Range of 1 $\sim$ 6 (1 $\sim$ 6 GHz대역 수풀손실 특성 측정 및 모델링)

  • Park, Yong-Ho;Jung, Myoung-Won;Han, Il-Tak;Pack, Jeong-Ki
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • pp.163-168
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    • 2005
  • Attenuation in vegetation is important, for both terrestrial and earth-space systems. However, the wide range of conditions and types of foliage makes it difficult to develop a generalized prediction procedure. Currently, there is also a lack of suitably prediction model and measured experimental data for vegetation loss. So in this paper, vegetation loss data for four different tree-species, including Dawn-redwood tree, Plane tree, Pine tree and Fir tree are obtained by measurement in the frequency range of 1.0 $\sim$ 6.0 GHz. The through or scattered component is calculated using a model based upon the theory of RET(Radiative Energy Transfer) and RET modeling parameters are extracted from the measured data.

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Determination of Permissible Shear Stresses on Vegetation Mats by Soil Loss Evaluation (토양 손실 평가에 의한 식생매트의 허용 소류력 결정)

  • Lee, Du Han;Rhee, Dong Sop;Kim, Myounghwan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.11
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    • pp.5956-5963
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    • 2013
  • By the activation of environment-friendly river works, application of vegetation mats is increasing, however, evaluation techniques for hydraulic stability of vegetation mats are not presented. This study is conducted to develop the objective test method for vegetation mats. Two kind of vegetation mats are tested by the real scale experiments, and hydraulic quantities are measured and analyzed to evaluate acting shear stresses. To evaluate soil loss, Terrestrial 3D LiDAR measurement is conducted and soil loss index are calculated from changes of bed elevation. Quantified evaluation for permissible shear stresses is conducted by graphical method for acting shear stresses and soil loss index. By the results of precision survey, changes of sub soil are limited to local range in stable cases and relatively large changes of sub soil which is similar to natural river bed are detected in unstable cases. From the study, evaluation of permissible shear stresses by ASTM D 6040 is avaliable in the failure mechanism and failure criteria by soil loss index.

Reduction of Soil Loss from Sloped Agricultural Field by using Hydrated Lime (소석회를 이용한 급경사 농경지 토양유실 저감)

  • Koh, Il-Ha;Yu, Chan;Park, Mi Jeong;Ji, Won Hyun
    • Journal of Soil and Groundwater Environment
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    • v.24 no.2
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    • pp.1-7
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    • 2019
  • The feasibility of using hydrated lime ($Ca(OH)_2$) was assessed in reducing soil loss in sloped land under field condition. During 6-month monitoring from May to October, amendment of hydrated lime (3%, w/w) to a test plot decreased soil loss by 76% as compared to the unamended plot. However, the growth of natural vegetation was hampered by hydrated lime addition due to pH increase. Hydrated lime can be used as an effective agent to prevent soil loss in sloped land, but additional treatments are needed to preserve vegetation growth, especially in crop fields.

A Study on Pressure Loss by the Material of AHU-linked Vegetation Bio-filter and its Operational Energy Efficiency

  • Kim, Tae-Han;Lee, So-Dam;Park, Sung-Eun
    • Journal of People, Plants, and Environment
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    • v.20 no.5
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    • pp.485-494
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    • 2017
  • Recently, the air quality issue came to the fore to the occupants of indoor areas with the detection of a large amount of indoor air pollutants such as formaldehyde that causes headache and atopic dermatitis. In order to address this issue, the use of indoor air purifying plants is considered positively as an ecological improvement option. However, the objective performance verification on indoor air-conditioning air volume has not been sufficient. This study aims to verify possible linkage with a building's air conditioning equipment in order to optimize indoor air-conditioning effects by vegetation bio-filters. To this end, 4 different types of air filter material and AHU (Air Handling Unit) system were linked under air conditions of total wind volume of 400, 600, 800, 1,000 CMH and pressure loss by material was monitored objectively. Finally, material-specific power consumption for system operation was calculated to review energy efficiency. As for pressure loss by material, in terms of total wind volume of $800{\pm}1.8CMH$, Pre filter was lowest at -11.69 mmAq and LMF-based vegetation mat was highest at -219.94 mmAq. Based on this, as for material-specific power consumption, the Pre filter, which has the lowest pressure loss, was expected to have power consumption 94.7% lower than the LMF-based vegetation mat.

An Experimental Study on Soil Loss Rate of Recovery Soil Technique at High Water Revetment (고수호안 복토공법의 토양 유실율에 관한 실험적 연구)

  • Chae, Dong-Seok;Kim, Young-Do;Park, Jae-Hyeon;Kim, Chul
    • Journal of Korean Society of Hazard Mitigation
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    • v.10 no.2
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    • pp.135-141
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    • 2010
  • Recently, to ensure the stability of flood control, instead of removal of concrete revetment, the vegetation mat method has been widely used on the recovery soil. However, the recovery soil method often failed to be stable against the flood, which caused the economic loss. In this study, the rate of soil loss and the velocity distribution on high water revetment are evaluated by the hydraulic experiments. The maximum difference of the soil loss rate was 52% depending on the vegetation. The reduction of the soli loss rate according to the vegetation is large when the revetment slope is steep. The maximum soil loss rate is 19.5% when there is no vegetation.

Measurement and Modeling of Vegetation Loss in the Frequency Range of 1~6 GHz (1~6 GHz 대역 수풀 손실 특성 측정 및 모델링)

  • Han, Il-Tak;Jung, Myoung-Won;Back, Jung-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.1
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    • pp.96-104
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    • 2007
  • Currently, there is a lack of suitable prediction model and measurement data for vegetation loss. So in this paper, vegetation loss measurement has been performed for seven different tree-species, including dawn-redwood tree, plane tree, pine tree and hymalaya cedar in the frequency range of $1.0{\sim}6.0\;GHz$, for the two years, from 2005 to 2006 years. And then, extraction and revision for the proposed RET model input parameters in ITU-R P.833 has been performed. The key results of measurement and RET modeling has been presented in this paper. The results of this study have been adapted for ITU-R recommendation at the ITU-R meeting in 2005 and 2006.

Effect of Red Pepper Canopy Coverages on Soil Loss and Runoff from Sloped Land with Different Transplanting Dates (경사지에서 고추 정식시기에 따른 토양유실과 유출수에 대한 식생피복 효과)

  • Cho, H.R.;Ha, S.K.;Hyun, S.H.;Hur, S.O.;Han, K.H.;Hong, S.Y.;Jeon, S.H.;Kim, E.J.;Lee, D.S.
    • Korean Journal of Soil Science and Fertilizer
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    • v.43 no.3
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    • pp.260-267
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    • 2010
  • As sloped farmland is subject to runoff and soil erosion and consequently require appropriate vegetative coverage to conserve soil and water, a field study was carried out to evaluate the impact of crop canopy coverage on soil loss and runoff from the experimental plot with three different textural types (clay loam, loam, and sandy loam). The runoff and soil loss were examined at lysimeters with 15% slope, 5 m in length, and 2 m in width for five months from May to September 2009 in Suwon ($37^{\circ}$ 16' 42.67" N, $126^{\circ}$ 59' 0.11" E). Red pepper (Capsicum annum L. cv. Daechon) seedlings were transplanted on three different dates, May 4 (RP1), 15 (RP2), and 25 (RP3) to check vegetation coverage. During the experimental period, the vegetation coverage and plant height were measured at 7 day-intervals and then the 'canopy cover subfactor' (an inverse of vegetation cover) was subsequently calculated. After each rainfall ceased, the amounts of soil loss and runoff were measured from each plot. Under rainfall events >100 mm, both soil loss and runoff ratio increased with increasing canopy cover subfactor ($R^2$=0.35, p<0.01, $R^2$=0.09, p<0.1), indicating that as vegetation cover increases, the amount of soil loss and runoff reduces. However, the soil loss and runoff were depending on the soil texture and rainfall intensity (i. e., $EI_{30}$). The red pepper canopy cover subfactor was more highly correlated with soil loss in clay loam ($R^2$=0.83, p<0.001) than in sandy loam ($R^2$=0.48, p<0.05) and loam ($R^2$=0.43, p<0.1) plots. However, the runoff ratio was effectively mitigated by the canopy coverage under the rainfall only with $EI_{30}$<1000 MJ mm $ha^{-1}hr^{-1}$ ($R^2$=0.34, p<0.05). Therefore, this result suggested that soil loss from the red pepper field could be reduced by adjusting seedling transplanting dates, but it was also affected by the various soil textures and $EI_{30}$.

Non-linear dynamics of wetland vegetation induced by groundwater table (지하수위와 연계된 습지 식생의 비선형 동역학)

  • Lee, Okjeong;Kim, Sangdan
    • Journal of Wetlands Research
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    • v.21 no.2
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    • pp.132-139
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    • 2019
  • Bi-directional interaction between vegetation and groundwater table has a great influence on the dynamics of wetland vegetation. In this study, nonlinear dynamics of wetland vegetation affected by groundwater are analyzed. The effect on groundwater is described as a loss term in the governing equation of wetland vegetation and it is explored how the wetland vegetation is likely to converge into two attractors by groundwater table change. From this conceptual approach, the vulnerability to catastrophic shifts in stable state where the current vegetation species are extinct and stabilized by other vegetation species is analyzed in response to groundwater table.

Energy Conservation for Runoff and Soil Erosion on the Hillslope (산지사면의 유출 및 토양침식에 대한 에너지 보존)

  • Shin, Seung-Sook;Park, Sang-Deog;Cho, Jae-Woong;Hong, Jong-Sun
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.234-238
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    • 2008
  • The energy conservation theory is introduced for investigating processes of runoff and soil erosion on the hillslope system changed vegetation condition by wildfire The rainfall energy, input energy consisted of kinetic and potential energy, is influenced by vegetation coverage and height. Output energy at the outlet of hillslope is decided as the kinetic energy of runoff and erosion soil, and mechanical work according to moving water and soil is influenced dominantly by the work rather than the kinetic energy. Relationship between output and input energy is possible to calculate the energy loss in the runoff and erosion process. The absolute value of the energy loss is controlled by the input energy size of rainfall because energy losses of runoff increase as many rainfall pass through the hillslope system. The energy coefficient which is dimensionless is defined as the ratio of input energy of rainfall to output energy of runoff water and erosion soil such as runoff coefficient. The energy coefficient and runoff coefficient showed the highest correlation coefficient with the vegetation coverage. Maximum energy coefficient is about 0.5 in the hillslope system. The energy theory for output energy of runoff and soil erosion is presented by the energy coefficient theory associated with vegetation factor. Also runoff and erosion soil resulting output energy have the relation of power function and the rates of these increase with rainfall.

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A Study on Soil Environment in Highway Cutting Slope and Adjacent Natural Vegetation Area (고속도로 절토 비탈면과 인접 자연식생지의 토양 환경 비교 분석)

  • Park, Gwan-Soo;Jeon, Gi-Seong;Song, Ho-Kyung;Kim, Nam-Choon;Choi, Jae-Yong
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.9 no.2
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    • pp.16-22
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    • 2006
  • This study was carried out to estimate the physical and chemical soil characteristics in highway cutting slope areas. The soil was sampled in cutting area and natural vegetation area that was located in the upper areas of the highway cutting slope. The average total soil depth, bulk density, and soil hardness were bad in the highway cutting slope sites. The sandy loam was the most soil texture in the study area. The concentration of soil organic matter and nitrogen were very low in all highway cutting areas. The concentration of exchangeable cations was similar between the highway cutting slope and the natural vegetation sites in each highway. The soil pH was higher in highway cutting slope areas than in natural vegetation sites. In conclusion, chemical and physical properties of soil were bad in the cutting slope than in the natural vegetation area because of the loss of soil by cutting of slope area and less organic matter input by less vegetation in the highway cutting slope area. We should employ possible method to reduce the loss of soil, and compost and fertilization treatment could help to increase soil nutrient content in the cutting slope area.