• Title/Summary/Keyword: soil damage

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Relation between Cone Tip Resistance and Deformation Modulus of Cemented Sand (고결모래의 콘선단저항과 변형계수의 관계)

  • Lee, Moon-Joo;Choi, Sung-Kun;Choo, Hyun-Wook;Lee, Woo-Jin
    • Journal of the Korean Geotechnical Society
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    • v.24 no.12
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    • pp.53-63
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    • 2008
  • In this study, the cone tip resistances of cemented sand are measured by performing a series of miniature cone penetration tests in large calibration chamber, and the relations with constrained modulus, unconfined compressive strength, and shear strength of cemented sand are suggested. Experimental results show that both the cone tip resistance and constrained modulus of sand increase with increasing cementation effect as well as relative density and confining stress. However, it is observed that the relative density and confining stress have more significant influence on cone tip resistance than constrained modulus of cemented sand. Since the cone penetration into the ground induces the damage of cementation, the cone tip resistance can't properly reflect the cementation effect of sand. An analysis based on the constrained modulus shows that the measured cone tip resistance underestimates the deformation modulus of cemented sand by about $70{\sim}85%$. In addition, this study establishes various relationships among the above soil properties from the regression analysis.

Seismic Risk Assessment of Extradosed Bridges with Lead Rubber Bearings (LRB 면진장치가 설치된 엑스트라도즈드교의 지진위험도 평가)

  • Kim, Doo Kie;Seo, Hyeong Yeol;Yi, Jin-Hak
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1A
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    • pp.155-162
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    • 2006
  • This study presents the seismic risk assesment for an extradosed bridge with seismic isolators of lead rubber bearings(LRB). First, the seismic vulnerability of a structure and then the seismic hazard of the site are evaluated using earthquake data set and seismic hazard map in Korea, and then the seismic risk of the structure is assessed. The nonlinear seismic analyses are carried out to consider plastic hinges of bridge columns and nonlinear characteristics of soil foundation. The ductility demand is adopted to describe the nonlinear behavior of a column, and the moment-curvature curve of a column is assumed to be bilinear hysterestic. The fragility curves are represented as a log-normal distribution function for column damage, movement of superstructure, and cable yielding. And seismic hazard is estimated using the available seismic hazard maps. The results show that the effectiveness of the seismic isolators for the columns is more noticeable than those for cables and girders, in seismic isolated extradosed bridges under earthquakes.

Analysis of outflow reduction effect of bioretention in small watersheds during short-term rainfall (단기강우 시 소유역내 식생저류지의 유출량 저감성능 분석)

  • Kim, Jaemoon;Baek, Jongseok;Kim, Byungsung;Kwon, Soonchul
    • Journal of Korea Water Resources Association
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    • v.56 no.12
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    • pp.855-869
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    • 2023
  • Low Impact Development (LID) technology has been attracting attention as a countermeasure to solve frequent flood damage in urban areas. LID involves recovery of the natural circulation system based on infiltration and storage capacity at the site of rainfall runoff, to protect the aquatic ecosystem from the effects of urbanization. Bioretention as an element of LID technology reduces outflow through storage and infiltration of storm water runoff, and minimizes the effects of non-point pollutants. Although LIDs are being studied extensively, the amount of quantitative research on small watersheds with bioretention has been inadequate. In this study, a bioretention model was constructed in a small watershed using Korea-Low Impact Development Model (K-LIDM), which was conducted quantitative hydrologic analysis. We anticipate that the results of the analysis will be used as reference data for future bioretention research related to watershed characteristics, vegetation type, and soil condition.

Constructing an Internet of things wetland monitoring device and a real-time wetland monitoring system

  • Chaewon Kang;Kyungik Gil
    • Membrane and Water Treatment
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    • v.14 no.4
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    • pp.155-162
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    • 2023
  • Global climate change and urbanization have various demerits, such as water pollution, flood damage, and deterioration of water circulation. Thus, attention is drawn to Nature-based Solution (NbS) that solve environmental problems in ways that imitate nature. Among the NbS, urban wetlands are facilities that perform functions, such as removing pollutants from a city, improving water circulation, and providing ecological habitats, by strengthening original natural wetland pillars. Frequent monitoring and maintenance are essential for urban wetlands to maintain their performance; therefore, there is a need to apply the Internet of Things (IoT) technology to wetland monitoring. Therefore, in this study, we attempted to develop a real-time wetland monitoring device and interface. Temperature, water temperature, humidity, soil humidity, PM1, PM2.5, and PM10 were measured, and the measurements were taken at 10-minute intervals for three days in both indoor and wetland. Sensors suitable for conditions that needed to be measured and an Arduino MEGA 2560 were connected to enable sensing, and communication modules were connected to transmit data to real-time databases. The transmitted data were displayed on a developed web page. The data measured to verify the monitoring device were compared with data from the Korea meteorological administration and the Korea environment corporation, and the output and upward or downward trend were similar. Moreover, findings from a related patent search indicated that there are a minimal number of instances where information and communication technology (ICT) has been applied in wetland contexts. Hence, it is essential to consider further research, development, and implementation of ICT to address this gap. The results of this study could be the basis for time-series data analysis research using automation, machine learning, or deep learning in urban wetland maintenance.

Development and Performance Analysis of Self-Propelled Crawler and Gathering Type Potato Harvester (크롤러 타입 자주식 수집형 감자 수확기 개발 및 성능분석)

  • Won-Kyung Kim;Sang Hee Lee;Deok Gyu Choi;Seok Ho Park;Youn Koo Kang;Seok Pyo Moon;Chang Uk Cheon;Young Joo Kim;Sung Hyuk Jang
    • Journal of Drive and Control
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    • v.21 no.2
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    • pp.23-29
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    • 2024
  • Potatoes are one of the world's four major crops, and domestic consumption is currently increasing in Korea. However, the mechanization rate of potatoes is very low, and especially, harvesting is the most labor-intensive task in potato production. In Korea, potato-collecting work depends on manpower, so it is necessary to develop a gathering-type harvester that can be used for processes from digging to harvesting. Therefore, in this study, a self-propelled-type potato harvester was developed, and its performance was analyzed to mechanize harvesting. The potato harvester was developed to have a crawler-type driving part with a 60 hp diesel engine and consisted of a digging part that digs potatoes from the ground, a vertical transporting part that transfers the dug potatoes to the height of the collection bag, a separating part that separates debris, such as stones and soil, and a collecting part that loads the collection box. A field test of the potato harvester was conducted, and performance was evaluated by the damage, loss, and debris mixing proportions, which were 2.5%, 2.8%, and 2.6%, respectively. The working capacity was 1.2 h/10 a. The economic analysis results showed that the cost of harvesting work could be reduced by 12.7% compared to manual harvesting.

Growth Response of Abies koreana (E. H. Wilson) under Different Shading Treatment (차광처리에 따른 구상나무 묘목의 생장특성)

  • Park, Byeong-Joo;Kim, Young-Hoon;Park, Sung-Hyuk;Han, Sung-Kyung;Kim, Jong-Kap;Heo, Tae-Im;Lee, Sang-Yong
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.27 no.5
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    • pp.1-12
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    • 2024
  • The purpose of this study is to provide basic data for sustainable production by investigating the growth characteristics of the endangered Korean fir (Abies koreana) under shading treatments. It was found that there was a temperature difference of approximately 6℃ between the shading treatment and the control group, and a difference of about 13% in soil moisture content. Only in the shading treatment group did dead individuals of Korean fir appear, and it was confirmed that other individuals also suffered from leaf withering and other physiological damage. The growth response of root diameter was observed in T2, and the growth of seedling height was observed in T3, indicating that satisfactory growth was observed in over 50% of the shading treatment groups. Total Chlrolophyll was higher according to the shading treatment(p<0.05), This trend is thought to be due to the short-term nature of the experiment, and it is expected that statistical significance will be observed after long-term adaptation. It is considered that over 50% shading effect will be beneficial for survival and growth in Abies koreana over 5 years old at the seedling stage.

Changes in the Organic Compound Contents of the Pear Rootstocks Pyrus calleryana and Pyrus betulaefolia Affected by Excessive Soil Moisture (토양 과습처리에 의한 배 대목 Pyrus calleryana 와 Pyrus betulaefolia 집단의 유기물 함량 변화)

  • Won, KyungHo;Kim, Yoon-Kyeong;Ma, Kyeong-Bok;Shin, Il-Sheob;Lee, Ug-Yong;Lee, Byul-Ha-Na;Choi, Jin-Ho;Lee, In-Bok;Kim, Myung-Su
    • Korean Journal of Environmental Agriculture
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    • v.35 no.3
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    • pp.175-183
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    • 2016
  • BACKGROUND: There's a long rainy season during the Summer in Northeast Asia, including Korea. Heavy rainfall during this season causes harm to tree's root, and damped injury in the pear has been continuously reported. Pear Research Institute is breeding damp resistant rootstocks and investigating their mechanisms to relieve damped damages in the pear.METHODS AND RESULTS: Seedlings of Pyrus betulaefolia and P. calleryana were divided into two groups: control and damped, respectively. Damped group was treated by constant irrigation for 77 days and control group was maintained to keep the soil moisture pressure between 0 and -10 kPa. After the treatment, we analysed trees' growth rate, chlorophyll content, amino acids and total phenolic compounds. As a result, P. betulaefolia was sensitive to damped treatment while P. calleryana did not have significant differences between the control and damped treatment. It was observed that total contents for phenolic compounds were dramatically increased in P. betulaefolia while trees' growth rate, chlorophyll b and general amino acid contents were lowered by damping treatment.CONCLUSION: In some pear cultivars, growth habit is suppressed by damped damage. Pyrus calleryana displayed tolerances to damped damage in growth rate and some organic compound contents compared to P. betulaefolia. So we recommend to exploit P. calleryana as a pear rootstock rather than using P. betulaefolia.

Assessment of Salt Damage for Upland-Crops in Dae-Ho Reclaimed Soil (대호 간척지 토양의 염농도별 밭작물의 염해 평가)

  • Lee, Seung-Heon;Yoo, Sun-Ho;Seol, Su-Il;An, Yeoul;Jung, Yeong-Sang;Lee, Sang-Mo
    • Korean Journal of Environmental Agriculture
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    • v.19 no.4
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    • pp.358-363
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    • 2000
  • This study was carried out to obtain the basic data for selecting the applicable crops in reclaimed land during desalinization period. A pot experiment was conducted with 5 different electrical conductivities of the saturated extracts $(ECe\;1,\;3,\;9,\;14,\;and\;16\;dS{\cdot}m^{-1})$ of soils taken from the Dae-Ho reclaimed tidal lands. Eight crops (Chinese cabbage, radish, tomato, red pepper, buckwheat, soybean, sesame, and green perilla) were grown for 37days. Plant height and number of leaves were surveyed on 2 and 4 weeks after seeding, and on harvest time (5 weeks). After harvest, dry weights of harvested crops were measured and soil chemical properties were analyzed. Emergence rates of crops were comparatively high except sesame. For sesame, there was no emergence at ECe over $3\;dS{\cdot}m^{-1}$. Growth and dry weight decreased significantly as increasing ECe. The ECe which decreased 50% of dry weight index were $14.2\;dS{\cdot}m^{-1}$ for radish, $11.4\;dS{\cdot}m^{-1}$ for Chinese cabbage, $10.2\;dS{\cdot}m^{-1}$ for red pepper, $8.9\;dS{\cdot}m^{-1}$ for buckwheat and green perilla, $8.6\;dS{\cdot}m^{-1}$ for soybean, and $8.9\;dS{\cdot}m^{-1}$ for tomato. At higher ECe that start the growth inhibition, increasing $1\;dS{\cdot}m^{-1}$ in ECe, 7.7, 6.5, 5.9, 5.6, 5.2, and 4.9% of dry weight decreased for buckwheat, green perilla, Chinese cabbage, radish, soybean, and tomato (red pepper), respectively. The critical value of ECe for crop survival except sesame was $15.4\;{\sim}\;23.1\;dS{\cdot}m^{-1}$.

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The Study of Solid Waste Compost Development for Reclaiming Damage Soil in Forest (산림훼손토양 복원을 위한 부숙토 개발 연구)

  • Na, Seung-Ju;Chang, Ki-Woon;Yang, Hui-Young;Jeon, Han-Ki;Lee, Jong-Jin
    • Journal of the Korea Organic Resources Recycling Association
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    • v.13 no.2
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    • pp.107-120
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    • 2005
  • To study the development of solid waste compost to use sewage sludge and paper mill sludge for reclaiming damage soil in forest, the changes of temperature, moisture, chemical properties, heavy metals and harmful compound during the aerobic decomposition were investigated, and the compost decomposition of final products investigated the round paper chromatography method and G.I(Germination index) value. The results were summarized as follows. Temperature was changed a little during early 5days because of air temperature too low. That was rapidly increased to over $50^{\circ}C$ at 4days after first turning and then decreased gradually fallen to $40{\sim}50^{\circ}C$ at 15days after aerobic decomposition in A and C treatments. The second turning was conducted at 18 days after aerobic decomposition, and then the temperature was little changed. At the compare first with terminal product, The moisture content was decreased all treatments but the change was little in A and B treatments. pH was decreased to below 1 in all treatments. EC was increased to below 5dS/m. The content of total carbon, C/N ratio, $NH_4{^+}-N$ were decreased with 4~7%, below 8 and below 500mg/kg in all treatments, respectively. The content of total nitrogen, $NO_3{^-}-N$, CEC were increased with below 0.5%, below 173mg/kg and over $30cmol^+/kg$ in all treatments, respectively. The content of heavy metals and harmful compound were similar during aerobic decomposition and suited to standard of 가 grade in all treatments. The result of round paper chromatography method and G.I. value, The C treatment concluded well aerobic decomposition. Especially, the G.I. value in C treatment was 64.1 and 66.2 at cabbage and grass, respectively.

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Studies on the Salt Tolerance of Rice and Other Crops in Reclaimed Soil Areas -1. On the Salt Tolerance of Rice Varieties (간척지에서 수도 및 기타작물의 내염성에 관한 연구 -1. 수도품종의 내염성에 관하여-)

  • Hyong-Bin Im;Jai-Wook Shim
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.8 no.1
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    • pp.47-68
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    • 1970
  • Experiments were conducted by moderate season culture of each of 7 early, medium and late maturing varieties which were considered to be of strong salt tolerance in non-salty, low- and high-salty reclaimed areas (salt content: 0.5% and 1% at the end of April). The results of the experiments revealed that the early maturing varieties were suffered greatly from salt damage in such reclaimed salty area which is the "fall better type" in the year-round changes of soil salt concentration in Korea. Better yielding varieties in the salty area showed generally a high yield ratio in the salty area compared with the non-salty area. This indicates that they are strong salt tolerant varieties. It seemed that the salt tolerance could be measured by the number of delaying days in heading, the growth rate of culm length, number of panicles and number of grains per panicle in the salty area to compare with the non-salty area. The effects or salt damage on the yields of each variety at maturing stage and agronomic characteristics in the salty area were compared and discussed with the non-salty area.alty area.

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