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화강암 풍화토의 동상 발현 및 융해에 따른 변형 거동에 관한 연구
류능환 ( Ryu Neung Hwan ),최중대 ( Choi Jung Dae ),류영선 ( Ryu Young Sun ) 한국농공학회 1995 韓國農工學會誌 : 전원과 자원 Vol.37 No.3
Natural ground is a composite consisted of the three phases of water, air and soil paircles. Among the three components, water as a material is well understood but soil particles are not in foundation engineering. Especially, weathered granite soil generally shows a large volumetric expansion when they freeze. And, the stability and durability of the soil have shown decreased with repetitive freezing and thawing processes. These unique charcteristics may cause various construction and management problems if the soil is used as a construction material and foundation layers. This project was initiated to investigate the soil's physical and engineering characteristics resulting from freezing and freezing-thawing processes. Research results may be used as a basic data in solving various problems related to the soil's unique characteristics. The following conclusions were obtained: The degree of decomposition of weathered granite soil in Kangwon-do was very different between the West and East sides of the divide of the Dae-Kwan Ryung. Soil particles distributed wide from very coarse to fine particles. Consistency could be predicted with a function of P<sub>200</sub> as LL=0.8 P<sub>200</sub>+20. Permeability ranged from 10<sup>-2</sup> to 10<sup>-4</sup>cm/sec, moisture content from 15 to 20% and maximum dry density from 1.55 to 1.73g /cm<sup>3</sup> By compaction, soil particles easily crushed, D<sub>50</sub> of soil particles decreased and specific surface significantly increased. Shear characteristics varied wide depending on the disturbance of soil. Strain characteristics influenced the soil's dynamic behviour. Elastic failure mode was observed if strain was less than 10<sup>-4</sup>/s and plastic failure mode was observed if strain was more than 10<sup>-2</sup>/s. The elastic wave velocity in the soil rapidly increased if dry density became larger than 1.5g /cm<sup>3</sup> and these values were V<sub>p</sub>=250, V<sub>g</sub>=150, respectively. Frost heave ratio was the highest around 0℃ and the maximum frost heave pressure was observed when deformation ratio was less than 10% which was the stability state of soil freezing. The state had no relation with frost depth. Over freezing process was observed when drainage or suction freezing process was undergone. Drainage freezing process was observed if freezing velocity was high under confined pressure and suction frost process was occurred if the velocity was low under the same confined process.
최용훈 ( Choi Yong Hun ),신민환 ( Shin Min Hwan ),김기철 ( Kim Ki Choel ),서지연 ( Seo Ji Yeon ),임경재 ( Lim Kyoung Jae ),최중대 ( Choi Jung Dae ) 한국농공학회 2008 한국농공학회 학술대회초록집 Vol.2008 No.-
Non-Point Source(NPS) type and quantity discharged are changed according to rainfall, rainfall intensity, duration, landuse, antecedent dry day. The research have made the flat plot and the sloping plot and executed a monitoring. The study have analyzed affect of the daily rainfall and rainfall intensity on runoff from sandy upland. The runoff did not occur from the rainfall of 30mm and above(March 22nd ~ 24th, May 18th, May 28th and June 28th ~ 29th). Because of weak rainfall intensity and long duration the runoff did not occur. The runoff occurred from 19mm rainfall of June 12th and 40mm rainfall of July 30th. Because of strong rainfall intensity and short duration the runoff did occur. Also accumulated rainfall is little, but runoff occurred because of concentration of rainfall. The result of research is the point that the different runoff occurs because of the rainfall intensity, when the same accumulated rainfall. Consequently, it was judged that rainfall intensity is the biggest effect to runoff of the sandy upland.
볏짚 피복에 의한 밭 비점원오염 저감효과 분석을 위한 HSPF 모델링
정충길,박종윤,이형진,최중대,김성준,Jung, Chung-Gil,Park, Jong-Yoon,Lee, Hyung-Jin,Choi, Joong-Dae,Kim, Seong-Joon 한국농공학회 2012 한국농공학회논문집 Vol.54 No.4
This study is to assess the reduction of non-point source pollution loads for rice straw surface covering of upland crop cultivation at a watershed scale. For Byulmi-cheon watershed ($1.21km^2$) located in the upstream of Gyeongancheon, the HSPF (Hydrological Simulation Program-Fortran), a physically based distributed hydrological model was applied. Before evaluation, the model was calibrated and validated using 9 rainfall events. The Nash-Sutcliffe model efficiency (NSE) for streamflow was 0.62~0.78 and the NSE for water quality (Sediment, T-N, and T-P) were 0.68, 0.60, and 0.58 respectively. From the field experiment of 16 rainfall events, the rice straw covering reduced surface runoff average 10 % compared to normal surface condition. By handling infiltration parameter (INFILT) in the model, the value of 16.0 mm/hr was found to reduce about 10 % reduction of surface runoff. For this condition, the reduction effect of Sediment, T-N, and T-P loads were 87.2, 28.5, and 85.1 % respectively. The rice straw surface covering was effective for removing surface runoff dependent loads such as Sediment and T-P.
침사기능 콘크리트 배수로의 유사 유출 저감에 관한 연구
신현준,원철희,최용훈,김태유,최중대,Shin, Hyun-Jun,Won, Chul-Hee,Choi, Yong-Hun,Kim, Tae-Yoo,Choi, Jung-Dae 한국농공학회 2010 한국농공학회논문집 Vol.52 No.6
Researchers developed Sediment Trap Drain Channel (STDC) as a solution of the reduction of soil erosion and muddy runoff from a alpine field. The STDC is the one that can take a role of grit chamber by installing the shield made of woods in the concrete channel. The study was conducted 8 kinds of stages according to the amount of soil loss and the inflow. Evaluation factors were ss concentration, turbidity and reduced soil. The results of study showed lessness of ss concentration and turbidity from the lower spot than the upper spot. The average reduction rate of ss concentration was 74 % and the average reduction rate of turbidity was 62 %. It was turned out that the performance related soil loss and muddy runoff of the STDC is effective. The governance was needed to expect the effectiveness of the STDC.
주진호,양재의,김정제,정영상,최중대,윤세영,유관식,Joo, Jin-Ho,Yang, Jae-E,Kim, Jeong-Je,Jung, Yeong-Sang,Choi, Joong-Dae,Yun, Sei-Young,Ryu, Kwan-Shig 한국토양비료학회 2000 한국토양비료학회지 Vol.33 No.2
Soil erosion in the hilly and mountainous uplands in the Daekwanryong area, Kangwon-Do, were investigated through a field plot experiment. The plot size was 15m long and 2.5m wide with the average slope of 12.5 percents. Soil erodibility factor (K), surface coverage (SC), soil aggregate percentage and wind erodibility (I) were evaluated in the mountainous soils under different management practices for corn and potato cultivations. Soil erodibility factor (K) was greater in upper part than in lower part of the plots. Surface coverage (SC) values ranged from 0.01 to 0.84 depending on the amounts of crop residues. Soils having a greater crop residue in surface were less subjected to soil erosion. SC values after corn harvest were 0.4 to 0.8, while those after potato harvest were 0.4 to 0.5, indicating potato might be better than corn for erosion control. Soil aggregate percentages of the experimental plots ranged from 49.7 to 79.8%. Those were higher in potato-cultivated plots with higher surface coverage, organic fertilizer treatment and contour tillage. Soil aggregate percentage of potato-cultivated plots was significantly correlated to crop residue coverage after harvest. The dried soil aggregate percentage, showing the ranges of 26.4 to 56.4%, were higher in the plots with the increased crop residue incorporation. Wind erodibility (I) of the soil was decreased with increasing surface coverage. When soil had 26.4% of the dried aggregate percentage, wind erodibility was estimated to be $183Mgha^{-1}$ which was equivalent to soil loss of $0.5Mg\ha^{-1}day^{-1}$. 강원도 평창군 도암면에 소재하는 농촌진흥청 고령지 농업시험장에 포장을 설치하여 옥수수와 감자 작부 체계 하에 토양의 토양피복인자 (SC), 내수성 토양 입단함량, 내풍식성 입단함량과 풍식성 인자 (I)를 조사하였다. 토양 침식인자 값 (K)은 실험 처리구의 상부가 하부보다 높았다. SC 값은 식물 잔재물의 양에 따라 다른 값을 보였으며, 0.01~0.84 이었다. 수확 후 식물 잔재물의 지면 피복도 (%)에 따른 SC 부요소 값은 옥수수 재배구에서 0.4~0.8 이며, 감자 재배구에서는 0.4~0.5이었다. 이는 감자 수확 시 잔재물이 옥수수 수확 시 잔재물에 비해 비교적 많이 남기 때문이었다. 시험 포지 토양의 입단함량 범위는 49.7~79.8%이었다 옥수수 재배구 중 화학비료 및 유기질 비료를 시용하고 등고선 경운 방법에 의한 처리구가 입단함량이 가장 높았다. 옥수수 수확 후의 피복도 (%)와 입단 함량 (%)의 관계는 회귀관계식이 성립되며, $r^2$는 0.96 이었다. 옥수수 재배구의 평균 입단함량이 감자 재배 포장의 평균 입단함량보다 다소 낮았다. 시험 포지 토양의 내풍식성 입단함량의 범위는 26.38~56.45% 이었다. 옥수수 재배구의 토양 입단 함량 (%)은 수확 후 잔재물과 유의성이 있었다. 옥수수 재배구 중 화학비료 및 유기질 비료를 시용하고 등고선 경운법에 의한 처리구의 경우 내풍식성 입단 함량은 26.42%로 풍식성 인자를 계산하면 $183Mgha^{-1}$이고, 토양의 휴조도 인자 (K')는 0.52이었다. 이에 따르면, 년 중 기상상태가 풍식이 일어날 수 있는 건조 상태일 경우 최대 풍식 가능량은 1일 $0.5Mgha^{-1}$에 해당하는 양이었다.
SWAT-REMM을 적용한 수변림 조성에 따른 하천오염부하 저감효과 분석
최윤호 ( Youn Ho Choi ),류지철 ( Ji Chul Ryu ),황하선 ( Ha Sun Hwang ),금동혁 ( Dong Huyk Kum ),박윤식 ( Youn Shik Park ),정영훈 ( Young Hun Jung ),최중대 ( Joong Dae Choi ),임경재 ( Kyoung Jae Lim ) 한국물환경학회 2015 한국물환경학회지 Vol.31 No.2
Pollutant in watersheds comes from two major sources which are NPS (nonpoint source pollution) and PS (point source pollution). Most of the pollutant can be treated by wastewater treatment plants. However, wastewater treatment plants may not be an appropriate practice to improve water quality for the watersheds with large portion of NPS pollutant and NPS pollution from direct runoff and baseflow has different characteristics. Therefore the practices to improve water quality need to be comprehensive for pollutants by both direct runoff and baseflow. Riparian buffer, one of practices to manage pollutant in watershed, has been applied to reduce pollutant not only from direct runoff but also baseflow. In this study, the scenarios for pollutant reduction by wastewater treat plants and the nitrogen reduction by riparian buffer were simulated using SWAT-REMM to suggest an effective plan for pollutant reduction from baseflow. Riparian buffer provided nitrogen reduction of 0.2~75.0% in YbB watershed and 38.0~47.0% in GbA watershed. The result indicates that riparian buffer is effective to reduce the pollutant especially from baseflow, and it suggested as suitable for the a watershed which WWTP discharge is not capable to reduce enough pollutant.