• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.227-229
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• 2004

The corrosion rate of buried steel pipes for water works was investigated under soil environment. Steel pipe shows various characteristics caused by complicated environment condition of underground and especially the corrosion rate of it depends on the resistivity of soil controlled by content of water. In this paper, the corrosion behavior of steel pipe was observed by polarization test under soil and the silica sand in the water content range of 0-50%. Generally it is well known that the resistivity of soil decreased rapidly over 15% water content. In fact the corrosion rate, corrosion potential, and corrosion consumption (MPY) of steel pipe were shown very different aspects within 20% water content.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.265-266
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• 2021

In this paper, we show the case of establishing a outdoor production system using the Internet of things and define the environmental variables in the outdoor production system. By measuring soil temperature, water content, electrical conductivity and acidity through sensors, LoRa communication module transmits the information to the outdoor production system. The outdoor production system controls the amount of fertilizer and the volume of water based on this sensor data. We have developed a system that manages a wide range of crops using LoRa technology, which is a suitable communication method for cultivating crops, and manages production volume and sales performance.

• Proceedings of the Korea Water Resources Association Conference
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• 1990.07a
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• pp.49-52
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• 1990

강우강도가 큰 집중호우가 지표면에 도달하게 되면 강우량중 상당 부분이 수문학적 손실성분인 침수, 증발산, 차단 및 저류등으로 시간에 따라 분포된다. 이 가운데 지표면에 분포된 식생계 및 낙엽등에 의한 차단(canopy interception effect)과, 지표가 포화시의 증발산(wetted environmental evapotranspiration) 및 각종 저류, 즉 지표면 저류(depression storage), 지표토양층에의 저류(retention storage) 성분 등을 들 수 있으며 이들 각 손실성분은 직접유출로 나타나는 초과우량의 발생시간을 지체시켜 주는 역할을 하나 차단성분 및 저류성분은 시간이 경과함에 따라 결국은 증발산 또는 침투성분으로 흡수된다. 따라서 침투성분은 초과우량 추정에 매우 큰 영향을 줄 뿐 아니라 지표면 아래의 흙의 변형을 야기시키며, 중간유출 및 지하수유출에 기여 한다. 대부분의 호우사상은 강우초기에 강우강도가 지표 흙의 침수계수(hydraulic conductivity)보다 작기 때문에 모두 각 손실성분에 의해 손실되며, 강우강도가 점차 커져 침수능을 초과하면 지표면에 순간적으로 물이 고이게 되는데 이것을 지표심수(surface ponding)라하고, 강우시작부터 이 때까지가 침수시간(ponding time)이 된다. 이 지표침수가 나타나는 순간이 곧 직접유출 시작 시간으로 볼 수 있을 뿐 아니라, 침수시간은 지표면의 물수지면에서 볼 때 초기손실량 및 침수율 결정에 중요한 인자가 된다. 본 연구에서는 각 손실 성분별로 유역의 제반 특성을 고려하여 구한 매개변수로부터 시간에 대한 손실율을 결정하여 산지 하천유역에 발생하는 부정강우사상(unsteady rainfall)의 초과우량을 추정하는 모델을 유도하였다. 대상유역으로는 현재 건설부에서 수행하고 있는 국제수문개발계획(IHP) 대표시험유역 가운데 평창강 수계내의 장평유역으로서, 본 유역은 자기 우량계 및 자기 수위계가 운용되고 있고, 인접 대관령 측후소로부터 기상자료를 획득, 이용할 수 있는 비교적 분석에 양호한 조건을 지닌 유역이다. 모델의 유도 과정은 대상유역 식생계로 피복된 산지유역임으로, 식생차단 저류효과를 고려해서 지표면의 흙에 도달되는 순강우주상도를 얻고 이로부터 침수시간 및 침투율을 결정해서 초과우량을 산정하는 모델을 유도하였다. 강우 지속시간내 즉, 유역이 완전 포화시의 증발산율의 결정은 Morton 모델로부터, 침수시간 및 침투율 결정은 Green-Ampt 방정식을 부정강우사상에 적용할 수 있도록 수정된 모델을 사용하였으며, 분석에 이용된 호우는 1986 ~ 1987년도 발생된 호우사상 가운데 강우강도 및 총 강우량이 비교적 큰 7개 강우사상을 선정하였다. 각 호우사상별로 손실율울 지표면에서 물수지개념을 이용하여 계산하고 산술지상에 구성시킨 결과는 다음 그림과 같다. 이 그림에서 굵은 실선으로 나타낸 곡선(B. L. R)은 각 손실을 곡선을 시간축에 따라 산술평균한 대표손실율곡선이다. 이 대표손실율곡선은 역지수함수형으로서 곡선식의 유도는 회기분석을 이용하였다. 초과우량 주상도를 얻기 위하여 이 대표손실을 곡선을 관측 강우주상도에 적용시켜 본 결과 식생계에 의한 차단 저류율은 약 6mm/hr 정도인 것으로 나타났으며, 이로 인한 침수시간 지체효과는 1~3시간 정도로서 비교적 그 영향이 큼을 알았다. 또한 각 호우사상별 침수시간 계산 결과 그 변동이 큰 것으로 나타났는데 이는 초기 강우강도에 민감하기 때문인 것으로 판단되낟. 한편 유역 포화시의 증발산율은 우기의 기상자료를 이용하여 구한 결과 0.05 - 0.10 mm/hr 의 범위로서 이로 인한 강우손실량은 큰 의미가 없음을 알았다.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.82-90
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• 2006

To examine the effects of nitrogen and phosphorus fertilization on soil nitrogen (N) mineralization, we monitored rates of soil nitrogen mineralization and nitrification in 41-year-old pitch pine (Pinus rigida Mill.) and Japanese larch (Larix kaempferi Gordon) stands growing on similar soil condition in central Korea. For this study, we used the buried-bag incubation method. Fertilizers were applied at three levels [control (C), 200 N kg/ha+25 P kg/ha (LNP), and 400 N kg/ha+50 P kg/ha(HNP)] on 5 June, 1996. Mineral soils (0~20 cm) were incubated 6 times with 45-day-interval from 5 June 1996 to 4 June 1997. Initial soil moisture contents were significantly different among sampling dates and between tree species. Initial soil moisture contents were 32% for C, 28% for LNP, and 26% for HNP at the P. rigida stand, and 31% for C, 31% for LNP, and 33% for HNP at the L. kaempferi stand, respectively. Mean daily N mineralization rates were significantly different among sampling dates and treatments. Annual net N mineralization and nitrification were also significantly different between the two tree species. The annual net N mineralization was 10.6 kg/ha/year for C, 23.3 kg/ha/year for LNP and 6.6 kg/ha/year for HNP at the P. rigida stand, and 2.0 kg/ha/year for C, 12.1 kg/ha/year for LNP and 16.7 kg/ha/year for HNP at the L. kaempferi stand. The annual nitrification was 2.8 kg/ha/year for C, 7.6 kg/ha/year for LNP and 4.3 kg/ha/year for HNP at the P. rigida stand, and 4.3 kg/ha/year for C, 14.8 kg/ha/year for LNP and 6.6 kg/ha/year for HNP at the L. kaempferi stand. The ratios of annual net nitrification to annual net N mineralization were 26% for C, 33% for LNP, 65% for HNP at the P. rigida stand, and 100% for C, 100% for LNP, 40% for HNP at the L. kaempferi stand, respectively. This study indicates that N mineralization in forest may be different by the predominant tree species and fertilization even under similar environments. It is likely that the quality of organic matter might control nitrogen mineralization and nitrification in soils.

• Korean Journal of Weed Science
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• v.16 no.2
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• pp.81-87
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• 1996

Seeds of rice, cv. Ilpoom, and barnyardgrasses(Echinochloa crus-galli, vars. oryzicola, crux-galli, and praticola) were sown for a characterization of their responses to temperature during emergence under a dry direct-seeded condition. A laboratory-made aluminum block apparatus for emergence-temperature control conferred a linear continuous temperature gradient from 10 to $30^{\circ}C$ to the seeds from cooling to heating ends of the apparatus. The lowest temperature for emergence was $12.3^{\circ}C$ for rice cv. Ilpoom, and $11.0^{\circ}C$ for the three varieties of Echinochloa spp.. Percent emergence of rice increased sharply with an increase in temperature by ca. $20^{\circ}C$, then leveled-off, while those of barnyardgrasses increased almost linearly with temperatures up to $30^{\circ}C$. In rice the time required for emergence after seeding was shortened exponentially with increased temperature while those for barnyardgrasses were shortened almost linearly from 11 to $30^{\circ}C$. The temperature-response characteristic of rice in emergence-speed was almost the same among those for the 1st emergence, emergence by 25, 50, 75%, or average emergence time. At $13^{\circ}C$, $346.7^{\circ}C$ days of accummulated temperature(26.67 days) were required for the 1st emergence in rice while 131.7, 136.0, and $138.7^{\circ}C$ days(10.13, 10.46, and 10.67 days) were required for the 1st emergence in E. spp., vars. crus-galli, praticola, and oryzicola, respectively. Greater cold tolerance and increasingly faster emergence of barnyardgrasses than rice below $20^{\circ}C$ seem to render the barnyardgrasses as much more competitive than rice at lower temperatures.

• Journal of the Korean Geosynthetics Society
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• v.11 no.4
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• pp.9-16
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• 2012

Standardized remediation process for the soil contaminated with arsenic is insufficient due to characteristics of its anion-mobility and speciation changed by Eh-pH of soil. One of the well-known efficient remediation processes is the modified soil washing that particle separation process by only water. However, it is required that the treatment plan for the fine soil what was discharged after modified soil washing. Therefore, this research suggests the treatment plan that the recycling method using arsenic immobilization by FeS-$H_2O_2$. The batch experiments results for the arsenic immobilization showed that the water content was at least 50%, the injection of FeS and $H_2O_2$ (assay-35%) were 8% (w/watdrybase) and 0.2 mL/10 g of fine soil respectively. Arsenic concentration with KSLT was decreased about 95.4%. The results indicated that the mixing of FeS-$H_2O_2$ was highly efficient on the immobilization of As-contaminated soil. The mixing ratio as 13% of bentonite with 3% of cement (at based on 100% of immobilized fine soil) was satisfied with standard of liner for landfill construction.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.3
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• pp.179-186
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• 2009

Relation between soil salinity and forage yield of five upland crops such as sudan grass, sesbania, barnyard grass, corn and soybean was studied in the three reclaimed lands of Korea during two years from 2007 to 2008. Although plant number emerged was obtained satisfactory by desalting treatment, further growth of crops was sharply affected by re-salting process according to soil drying. Soil salinity varied place by place and changed constantly, crop growth was differently responded to soil salinity according to the specific conditions of the reclaimed lands. In the Iweon reclaimed land with higher soil water conductivity and sandy soil texture, crop growth and yield sharply decrease with increase of soil salinity. Relation between soil salinity and crop growth and yield was well expressed as logarithmic function. Surface soil EC to reach at 50% of growth reduction to the tallest height of crops was $5dS\;m^{-1}$ for soybean, $6dS\;m^{-1}$ for corn and $7dS\;m^{-1}$ for sudan grass, sesbania, and barnyard grass by logarithmic function. In the Hwaong and Yeongsangang reclaimed lands with low soil conductivity and finer soil texture, plant growth response to salt stress was statistically vague by mixing of harmful influence from flooding and wet injury. However, it is observed that crop growth and yield on the place of lower salinity was better than crop growth on the place of higher salinity. It is accordingly concluded that flooding control during summer rainy season is vary important as well as desalting process for good growth of soiling and forage crops in the newly reclaimed land from tidal flat.

• Korean journal of applied entomology
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• v.56 no.1
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• pp.29-39
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• 2017

To compare the features of ground-dwelling invertebrates according agroecosystems, we selected paddy fields, dry fields, orchards in the Eastern region of Korea. The surveys were performed by using pit-fall traps twice per year from 2013 to 2015. Total 6,420 individuals of 172 species belonging to 13 orders, 58 families were investigated in the Eastern region, the species of Hymenoptera (38.26%), Orthoptera (16.28%) accounted large portion of the communities. In the geographical observation, invertebrates were caught was 2,983 individuals in Gyeongsangnam-do, the diversity index of Gyeongsangbuk-do community was higher than of the others and abundance and species richness of paddy field were higher than from dry field or orchard. To understand the relation between taxonomic groups and environmental factors, we carried out the canonical correspondence analysis and hierarchical clustering. As a result, Homoptera, Blattaria, Isoptera, and Coleoptera were positively related to soil pH, soil temperature, and moisture contents, and negatively related to the others. Invertebrate community also were patterned dependently by type of ecosystems. This results were shown that distribution of invertebrates is a few influenced the relationship of the space habituated invertebrates and environmental factors.

• Journal of Wetlands Research
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• v.24 no.3
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• pp.204-212
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• 2022

The LID technique began to be applied in Korea after 2009, and LID facilities are installed and operated for rainwater management in business districts such as the Ministry of Environment, the Ministry of Land, Infrastructure and Transport, and LH Corporation, public institutions, commercial land, housing, parks, and schools. However, looking at domestic cases, the application cases and operation periods are insufficient compared to those outside the country, so appropriate design standards and measures for operation and maintenance are insufficient. In particular, LID facilities constructed using LID techniques need to maintain the environment inside LID facilities because hydrological and environmental effects are expressed by material circulation and energy flow. The LID facility is designed with the treatment capacity planned for the water circulation target, and the proper maintenance, vegetation, and soil conditions are periodically identified, and the efficiency is maintained as much as possible. In other words, the soil created in LID is a very important design element because LID facilities are expected to have effects such as water pollution reduction, flood reduction, water resource acquisition, and temperature reduction while increasing water storage and penetration capacity through water circulation construction. In order to maintain and manage the functions of LID facilities accurately, the current state of the facilities and the cycle of replacement and maintenance should be accurately known through various quantitative data such as soil contamination, snow removal effects, and vegetation criteria. This study was conducted to investigate the current status of LID facilities installed in Korea from 2009 to 2020, and analyze soil changes through the continuity and current status of LID facilities applied over the past 10 years after collecting soil samples from the soil layer. Through analysis of Saturn, organic matter, hardness, water contents, pH, electrical conductivity, and salt, some vegetation-type LID facilities more than 5 to 7 years after construction showed results corresponding to the lower grade of landscape design. Facilities below the lower level can be recognized as a point of time when maintenance is necessary in a state that may cause problems in soil permeability and vegetation growth. Accordingly, it was found that LID facilities should be managed through soil replacement and replacement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.4
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• pp.493-503
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• 2019

This study is composed of nine treatments [Control : "no neutralizing layer+vegetation layer" 3 cm, Treatment 1 : "no neutralizing layer+vegetation layer" 5 cm, Treatment 2 : "no neutralizing layer+vegetation layer" 7 cm, Treatment 3 :"neutralizing layer (cement 3 %)+ vegetation layer (cement 1 %)" 3 cm, Treatment 4 : "neutralizing layer (cement 3 %)+vegetation layer (cement 1 %)" 5 cm, Treatment 5 : "neutralizing layer (cement 3 %)+vegetation layer (cement 1 %)" 7 cm, Treatment 6 : "neutralizing layer [$(Ca{\cdot}Mg)CO_3$] +vegetation layer" 3 cm, Treatment 7 : "neutralizing layer [$(Ca{\cdot}Mg)CO_3$]+vegetation layer" 5 cm, Treatment 8 : "neutralizing layer [$(Ca{\cdot}Mg)CO_3$]+vegetation layer" 7 cm] to find out the vegetation effects according to neutralizing layer types of the acid drainage slope. There were no significant differences observed in soil hardness and soil moisture content of neutralizing layer type while highly difference of moisture content was observed according to the neutralizing and vegetation layer thickness. As for soil acidity, strong acid was shown in the control, treatment 1 and treatment 2. Neutralizing effects were outstanding in treatments of 3, 4, 5 (cement treatment group), 6, 7 and 8 (limestone treatment group). Concerning plants growth characteristics, surface coverage rates, number of germinating woody plants, plant height, and plant root status, there were excellent effects observed in the experimental groups mixed with cement (treatments 3, 4 and 5) and limestone (treatments 6, 7 and 8). At the initial stage, however, plant roots were negatively affected in cement layer treatments of 3, 4 and 5. However, no difference was shown in each layer thickness on the acid drainage slope whereas 3~5 cm thickness neutralizing layer was appropriate in consideration of economic feasibility.