• Journal of Ecology and Environment
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• 제30권3호
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• pp.265-269
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• 2007

The loss of nitrogen and phosphorus from sediments in two watersheds, one naturally regenerating and one artificially planted, in Sacheon-myun, Gangneung-si, Gangwon Province, were measured two years after a forest fire in 2000. Sediment losses occurred five times in the course of the year. In the artificially planted watershed, $50{\sim}140$ times more nitrogen and $54{\sim}139$ times more phosphorus were lost with sediments during heavy rains, from July to August, than in the naturally regenerating watershed. When the typhoon Rusa struck the country, 1,389 times more nitrogen and 1,647 times more phosphorus were lost from the artificial watershed. In spite of the limited scope of this study, these results suggest that artificially planted watersheds are extremely vulnerable to catastrophic natural disasters such as typhoons. Elevated loss of nutrients in the artificially planted watershed might have resulted from the mechanized silvicultural practices employed immediately after the fire. To maximize soil preservation, the timing and necessity of plantation practices should be reconsidered, and rapidly regenerating vegetation should be protected to promote nutrient uptake and to mitigate nutrient loss from burned forests.

• 한국해양공학회지
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• 제21권1호
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• pp.75-80
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• 2007

Measuring the ground speed and the rotation speeds of tracks is an easy and realistic method to detect the track slips. It is very advantageous if the slips can be measured and applied to real time control of the vehicle. With a proper speed, the tractive force of a tracked vehicle may be calculated from the vehicle dynamics. For the control of tracked vehicle, the relationship between the slip and the tractive force is necessary. In this paper, a series of drawbar-pull tests, in which slips of two tracks are measured under the variational draw-bar weight, is executed to directly obtain the slip-tractive force relationship. For the purpose of the test, a tractive vehicle model was manufactured, and an artificial soil was simulated by using a bentonite-water mixture.

• Environmental Engineering Research
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• 제15권1호
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• pp.35-40
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• 2010

Bung Boraphet is the largest freshwater reservoir in Thailand. This study examined the accumulation of copper (Cu) and lead (Pb) in water, sediment and tissues of Asian clams (Corbicula sp.) within Bung Boraphet to assess the possible polluting effect of soil erosion and the dissolution of water soluble salts from the Nan River. Samples were collected from 12 study sites within Bung Boraphet between February and December 2008. The physicochemical parameters of the water including temperature, pH, turbidity, ammonia nitrogen, nitrate nitrogen, orthophosphates, biochemical oxygen demand, dissolved oxygen, Cu, and Pb were measured. The water in Bung Boraphet was found to be medium clean according to the surface water quality standard of Thailand. The levels of Cu and Pb in the water were low but heavy metals were detected at higher levels in the sediment and tissues of Corbicula sp. In the near future, management practices and regulator approaches for Cu and Pb contamination will be needed to protect the water in Bung Boraphet.

• 한국농공학회논문집
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• 제54권3호
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• pp.91-101
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• 2012

This study is to assess the runoff characteristics of nonpoint source pollution loads for Jecheon and Jangpyeong stream watersheds located in the upstream of Chungju lake. The SWAT (Soil and Water Assessment Tool), a physically based distributed hydrological model was calibrated and verified using 5 years (2006 to 2010) streamflow and water quality data. The Nash-Sutcliffe model efficiency for streamflow was 0.60~0.92 and the determination coefficients for sediment, Total Nitrogen (T-N), and Total Phosphorous (T-P) were 0.53~0.71, 0.51~0.91 and 0.38~0.85 respectively. The results showed that the Sediment, T-N, and T-P of Jangpyeong stream were 40.0~60.9 %, 34.8~64.1 % and 76.5~83.9 % higher than Jecheon stream watershed during wet days. The results evaluated high NPS loads at Jangpyeong stream because the percentage of urban and upland crop cultivation area Jangpyeong stream watershed was higher than Jecheon stream watershed.

• 한국산림과학회지
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• 제103권3호
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• pp.392-401
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• 2014

본 연구는 사방댐의 준설작업이 퇴사선내 계류의 지형변화에 미치는 영향을 알아보기 위해서 준설을 시행한 사방댐과 준설을 시행하지 않은 사방댐을 대상으로 지상 LiDAR 측량을 실시하고 경사도 및 체적의 지형변화를 평가하였다. 지상 LiDAR 장비는 사용자의 숙련도에 영향을 받지 않고 쉽게 지형변화를 관측할 수 있는 장점이 있다. 본 연구결과, 경사도 변화는 토양침식 유발의 위험이 높은 경사도($20^{\circ}{\sim}40^{\circ}$)가 차지하는 비율은 준설을 시행한 사방댐 지역보다 준설을 시행하지 않은 사방댐에서 수치적으로는 더 높게 나타났지만, 우기후 위험구역은 준설을 시행하지 않은 사방댐에서 더 감소하는 것으로 나타났다. 체적변화는 준설을 시행한 사방댐에서 침식과 퇴적이 규칙적인 양상으로 나타났지만, 준설을 시행하지 않은 사방댐에서는 침식과 퇴적이 불규칙적으로 나타났다. 그리고 정량적 분석결과 준설을 시행하지 않은 사방댐에 비해 준설을 시행한 사방댐에서 우기후 $m^2$당 1.7배 더 많은 토사가 유입되었다. 조사대상지의 강우량 차이는 토사유출량에 미치는 영향이 없는 것으로 나타났다. 따라서, 준설을 시행한 사방댐에서는 준설을 시행하지 않은 사방댐에서보다 우기를 지나면서 토양침식의 위험이 높은 경사도 분포가 증가하고, 준설작업을 시행한 지역의 상류계류에서 토사가 많이 유입된 것으로 나타났다.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2003년도 춘계학술대회
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• pp.148-148
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• 2003

This study is to investigate the environmental levels and trend of dioxins, which was the 3$\^$rd/ year of environmental monitoring research for endocrine disrupting chemicals since 1999. Total 282 samples were analyzed from 115 sites including 26 sites of airs, 43 sites of waters, 11 sites of sediments and 35 sites of soil, which were the same as those of investigated sites in 2000. Sampling period was from June 2001 to June 2002. Target chemicals were seventeen species of 2,3,7,8-chlorine-substituted PCDD and PCDF congeners and were analyzed by the standard methods, established by National Institute Environmental Research (NIER). The average concentration of dioxins in air decreased from 0.324 pg-TEQ/N㎥ in 2000 to 0.287 pg-TEQ/N㎥ in 2001, and those in water and soil were 0.073pg-TEQ/L and 1.703pg-TEQ/dry g, respectively, which was the less values detected in 2000. In sediment, however, the value was 0.086pg-TEQ/dry g, which was the increase from the value of the year 2000. The concentration range of dioxins in air for 26 sites in 17 regions detected were 0.013∼l.664pg-TEQ/N㎥, 4 sites from those were exceeded the Air Quality Standards of Dioxin in Japan (0.6 pg-TEQ/N㎥). The tolerable daily intake of dioxins was calculated at the highest level (1.664) in air, with referring the soil and food data from Japan, was calculated to be 2.85pg-TEQ/kg/day, which was below the level of 4 pg-TEQ/kg/day suggested in KFDA(Korea). While the average concentration of dioxins in 15 big cities was 0.190 pg-TEQ/N㎥, that in 8 medium/small cities constituting an industrial complex was 0.558 pg-TEQ/N㎥. In water, the concentration range detected were 0∼0.946pg-TEQ/L and the trend of the average concentrations shows an increase from those of 1999 but decreased from those of 2000, any sites however were not exceeded the Water Quality Standards of Dioxin in Japan (1 pg- TEQ/L). In soil. the detected range were 0∼43.333 pg-TEQ/dry g and the average concentration decreased, compared with the results of 2000. According to the monitoring results by land utilization, the detected range were 0∼43.333pg-TEQ/dry g in farmland, 0.017∼0.601 pg-TEQ/dry g in the industrial area, 0.005∼0.049pg-TEQ/dry g in the park and 0.008∼1.825 pg-TEQ/dry g in the rest. In sediment, the detected range increased from 0∼0.244 pg-TEQ/dry g to 0∼0.537 pg-TEQ/dry g, based on the results of 2000. For the proper control of dioxins, continuous monitoring needs to be performed and in addition, the dioxin inventory should be prepared for major sources through the dioxin emission survey. These results would provide sound and solid basis for proper decision making of dioxins management like establishment of environmental quality standards in Korea.

• 환경생물
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• 제17권3호
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• pp.337-344
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• 1999

본 연구는 온배수가 인근 소하천의 수질과 농경지내 오염성분함량 변동에 미치는 영향을 구명하고 이에 대한 대책을 수립하는데 활용하고자 1997년 1월부터 1998년 9월 사이에 수행되었다. 온배수 유입으로 인근 소하천 물 중의 $PO_4^{3-}, SO_4^{2-}, Cl^{-}$, $NH_4 -N, Ca^{2+}, Na+ $및 COD성분함량은 농업용수 기준보다 낮았으며 유거 거리가 길어질수록 이들 농도는 더욱 낮아졌다. 유출된 온배수 중 $SO_4^{2-}$.농도는 농업용수 기준을 초과하였으나, 유거되면서 비오염 하천수와 혼합되었을 때 그 농도는 농업용수기준보다 낮아졌다. 온배수 수로변 침전퇴적물중 S, T-N, 토양유기물, 인산의 농도는 배출구로부터 가까워질수록 높았으며 Ni, Fe, Zn, Cu, Pb와 같은 금속류 함량은 온배수 유입지에서 가장 높았다. 온배수가 유입되어도 논 토양 중 T-N, EC, S, 토양유기물, 인산 함량은 축적되지 않았는데 이는 벼와 같은 재배식물의 양분대사와 논 토양의 자정력에 기인한 것으로 보인다. 그러나 조사지역의 온배수로 벼를 재배해도 토양중 오염성분의 집적은 나타나지 않았으나 온배수 중 EC와 NO$_3$-N농도를 감안한다면 벼 재배시 장기간 관개용수로 다량 사용시에는 비료사용량을 줄여주는 것이 농업환경보전에 바람직할 것으로 사료된다.

• 대한원격탐사학회지
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• 제26권5호
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• pp.497-510
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• 2010

이 연구에서는 토양의 유전상수 (dielectric constant) 표면의 거칠기 (surface roughness)와 지표면의 기하 (geometric) 등과 같은 다양한 물리적 요소들의 정보를 포함하고 있는 SAR (Synthetic Aperture Radar) 자료를 이용하여 강화도 갯벌의 표층 퇴적환경을 분석하였다. JERS-1, ENVISAT과 ALOS 위성의 다양한 SAR 자료로부터 레이더 후방산란계수 (backscattering coefficient)를 추출하여 각 퇴적환경 요소들과의 관계를 파악하고 시간변화에 따른 지표의 변화 정도를 알 수 있는 긴밀도 (coherence)를 추출하여 퇴적상과 비교하였다. SAR 영상으로부터 추출한 후방산란계수와 긴밀도를 이용한 강화도 갯벌 퇴적환경 특성을 분석한 결과 높은 긴밀도를 갖는 지역은 입도가 작은 펄이 많이 포함된 펄 퇴적상이며 긴밀도가 낮을수록 큰 입도가 많이 분포하는 지역임을 알 수 있었다. 강화도 갯벌은 다른 갯벌과는 달리 조류로가 많이 발달하여 썰물 시 수분함유량에 많은 영향을 주어 모래 퇴적상과 혼합 퇴적상은 갯벌의 노출시간이 증가함에 따라 토양 수분함유량이 감소하여 후방산란계수가 점차 감소한다. 그러나 펄 퇴적상에서는 지형 고도가 높아 해수의 많은 영향을 받지 않으며 조류로의 밀도가 높기 때문에 토양 수분함유량이 감소하지만 후방산란계수가 높게 나타났다. 또한 갯벌은 토양 수분함유량뿐만 아니라 표면에 남아있는 잔존수도 많아 강우량이 많은 날은 지표 잔존수가 증가하기 때문에 비교적 후방산란계수가 낮게 나타나는 경향을 보였다. 이 연구의 결과, 긴밀도, 후방산란계수와 각 퇴적환경 요소들의 상관관계를 알 수 있었으며, 향후 강화도 갯벌 퇴적환경의 공간적 분석을 위해 각각의 요소들이 미치는 영향에 대한 정량적인 연구가 필요할 것으로 판단된다.

• 한국수자원학회논문집
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• 제34권1호
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• pp.3-17
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• 2001

본 연구는 개발활동에 의해 가속화되는 토사유출량의 발생규모를 토사유출량 산정모형을 이용하여 산정하고 현장에서의 토사발생량과 비교하여 모형의 적용성을 파악하는데 목적이 있다. 토사유출량 산정시 주로 적용되는 범양토양유실량식(USLE) 혹은 TRB(Transport Research Board) 모형등은 외국에서 개발되어 국내에서는 모형에 대한 검증과 검정이 구체적으로 수행되지 않은 상태로 이용되고 있으며 모형의 적용절차 및 한계에 대한 검토도 이루어지지 않은 상태이다. 본 연구에서는 충남 천안지역 개발현장에서의 토사발생량과 토사유출 발생규모를 조사하고 그 특성을 분석하였으며, 비교적 실무에서 적용가능한 범양토양 손실모형, Transport Research Board모형, MUSLE모형, Morgan과 Finney모형기법을 실유역에 적용한 예측값을 비교하여 모형의 적용성을 분석하였다. 모형의 적용결과 USLE모형과 TRB모형은 과대산정의 가능성이 있으며 단일호우에 대한 토사유출량을 산정하는 MUSLE모형이 상대적으로 실측치와 유사한 결과를 나타냈다. 이러한 결과는 토사유출을 위한 대책수립을 위한 기초자료로 사용될 수 있을 것이다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.151-151
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• 2011

Large amounts of natural gas, mainly methane, in the form of hydrates are stored on continental margins. When gas hydrates are dissociated by any environmental trigger, generation of excess pore pressure due to released free gas may cause sediment deformation and weakening. Hence, damage on offshore structures or submarine landslide can occur by gas hydrate dissociation. Therefore, geotechnical stability of gas hydrate bearing sediments is in need to be securely assessed. However, geotechnical characteristics of gas hydrates bearing sediments including small-strain elastic moduli have been poorly identified. Synthesizing gas hydrate in natural seabed sediment specimen, which is mainly composed of silty-to-clayey soils, has been hardly attempted due to their low permeability. Moreover, it has been known that hydrate loci in pore spaces and heterogeneity of hydrate growth in specimen scale play a critical role in determining physical properties of hydrate bearing sediments. In the presented study, we synthesized gas hydrate containing sediments in an instrumented oedometric cell. Geotechnical and geophysical properties of gas hydrate bearing sediments including compressibility, small-strain elastic moduli, elastic wave, and electrical resistivity are determined by wave-based techniques during loading and unloading processes. Significant changes in volume change, elastic wave, and electrical resistivity have been observed during formation and dissociation of gas hydrate. Experimental results and analyses reveal that geotechnical properties of gas hydrates bearing sediments are highly governed by hydrate saturation, effective stress, void ratio, and soil types as well as morphological feature of hydrate formation in sediments.