• Journal of Environmental Science International
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• v.2 no.2
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• pp.153-160
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• 1993

The problem of supply and transport of sediment from a mountainous catchment is very important in explaining dynamic geomorphology and the hydrological cycle. The discharge of suspended sediment is determined by a morphological system. Human interference to environment Is also an important, not negligible factor in sediment production. Moreover, growing concern in recent years for the problems of nonpoint pollution and for the transport of contaminants through terrestrial and aquatic ecosystems has highlighted the role of sediment-associated transport in fluvial systems. This study was conducted in forested and quarried catchments in order to clarify the different discharge process and the mechanism of suspended sediment dynamics for each catchment. As a forested catchment, the Yamaguchi River catchment which drains a $3.12km^2$ area was chosen. On the other hand, the Futagami River basin which is formed by three subbasins (1.07, 1.59 and $1.78km^2$), as a quarried catchment was selected. These catchments are situated to the north and east of Mt. Tsukuba, Ibaraki, Japan. The discharge pattern of suspended sediment from the Futagami River basin is more unstable and irregular than that from forested catchment, the Yamaguchi River catchment. Under the similar rainstorm conditions, suspended sediment concentration from quarried catchment during a rainstorm event increases from 43 to 27,340 mg/l. However, in the case of the forested catchment it changes only from nearly zero to 274 mg/l. Generally, the supply source of suspended sediment is classified into two areas, the in-channel and non-channel source areas. As a result of field measurements, in the case of the forested catchment the in-channel (channel bed, channel bank and channel margin) is the main source area of suspended sediment. On the other hand, remarkable sediment source area on the Quarried catchment is the non-channel that is unvegetated ground.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.2
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• pp.5-12
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• 2019

The study is carried out to survey the proper management and to propose an eco - friendly separation system through efficient screening and resource recovery of excavated materials containing waste from various excavating fields such as reconstruction of landfill sites for reuse, reclamation of unsanitary landfill and residential land development of waste dumping sites. The current status and screening process and analytical characteristics of the excavated materials containing waste were reviewed. Through the analysis of the samples such as separated combustibles, recyclable soils and residues collected from the on-site visits we were able to understand the characteristics of separated materials and excavated materials containing waste such as calorific value, elementary composition, TOC, foreign material content and LOI. It has been found that elimination of the moisture of excavations, removal of attached soil from the surfaces of the excavated combustibles and the quantitative supply method of the input devices are the main operating factors as essential factors for the optimal separation of excavated materials containing waste. For efficient management and recycling of excavated materials containing, it is necessary to set criteria of ash content in separated combustibles and criteria organic matter content in separated soils.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.16-21
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• 2019

This study has its aim to judge both applicability and suitability of recycling of waste soil for the use of farmland amelioration and low-lying farmland reclamation through growth and development experiment and component analysis. As results of physical characteristic evaluation on recycling of waste soil, the classification based on unified soil classification system has investigated as SW and SP affiliation and soil classification has appeared to be a loamy sand. As results of chemical component analysis, pH has appeared to be 7.0~8.4 which is relatively higher than general soil, however, heavy metal has investigated within the 1 region's standard value of soil pollution standards. As results of germination experiment, when using it by mixing recycling soil less than 75%, there is no significant influence on germination, and in the growth and development experiment, when using horticultural bed soil which is mixed with less than 40% of recycling of waste soil, it has confirmed that there is no significance difference with general soil. In case of farmland, the growth disorder of recycling of waste soil rate no more than 40% has shown that it has relatively small influences, and in case of using it by mixing with agricultural soil, it has evaluated to require concrete review of factors which may restrict growth condition including nutrition and pH.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.3
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• pp.323-345
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• 2019

It is essential to predict ground conditions ahead of a tunnel face in order to successfully excavate tunnels using a shield TBM. This study proposes a forward prediction method for a mixed soil ground and/or a ground containing core stones by using electrical resistivity and induced polarization exploration. Soil conditioning in EPB shield TBM is dependent upon the composition of mixed soils; a special care need to be taken when excavating the core-stoned soil ground using TBM. The resistivity and chargeability are assumed to be measured with four electrodes at the tunnel face, whenever the excavation is stopped to assemble one ring of a segment lining. Firstly, the mixed ground consisting of weathered granite soil, sand, and clay was modeled in laboratory-scale experiments. Experimental results show that the measured electrical resistivity considerably coincides with the analytical solution. On the other hand, the induced polarization has either same or opposite trend with the measured resistivity depending on the mixed ground conditions. Based on these experimental results, a method to predict the mixed soil ground that can be used during TBM tunnel driving is suggested. Secondly, tunnel excavation from a homogeneous ground to a ground containing core stones was modeled in laboratory scale; the irregularity of the core stones contained in the soil layer was modeled through random number generation scheme. Experimental results show that as the TBM approaches the ground that contains core stones, the electrical resistivity increases and the induced polarization fluctuates.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.536-549
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• 2005

국내 대부분을 차지하고 있는 NATM의 주요원리는 주변지반의 지보효과를 활용하는 터널굴착공법이다. 따라서 실제 지반조건이 원설계조건 보다 역학적으로 불량한 경우 보강공법의 적용은 필수적이라 할 수 있으나, 합리적인 설계변경은 현실적으로 쉽지 않은 실정이다. 또한 현실적인 이유로 양방향으로 터널을 관통하는 설계법과 달리 종종 1방향 굴진으로 터널을 관통하는 경우가 있다. 그러나 이러한 1방향 굴진은 불가분 굴진 종점부에서 저토피 갱구를 향하게 되므로, 지반이 연약한 경ㅇ우 막장 붕괴의 위험이 매우 높은 것으로 알려져 있다. 본 터널은 설계 시 갱구부 지반을 풍화암과 연암으로 보고 설계 하였으나, 실제 굴착 시 확인된 지층은 핵석을 포함한 실트질모래(SP-SM)로 판명되었다. 더구나 터널굴진 방향에 있어서도 양방향 굴착이 아닌 저토피 갱구를 향한 1방향 굴진을 실시하였으며, 이러한 시공 중에 터널관통을 불과 19m 남겨둔 갱구부에서 막장부괴와 동시에 상부사면 함몰이 발생하였다. 본 연구는 토사터널 갱구부 1방향 굴진 시 발생한 막장붕괴 보강사례로서, 지상보강(시멘트밀크 그라우팅)과 갱내보강(방사상 FRP보강그라우팅) 그리고 인버트폐합을 실시하여 성공적으로 터널시공을 완료한 사례연구이다. 본 사례는 향후 토사터널 갱구부의 설계와 시공에 유용한 참고자료가 될 것이다.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.1
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• pp.104-109
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• 2004

In this study, we stabilized the screened soil from landfills by using aerobic bioreactor and evaluated aerobic decomposition of it. Four lab-scale bioreactors (anaerobic and 1 PV/day aeration, 5 PV/day aeration, 10 PV/day aeration) filled with screened soil were operated to investigate the effect of air injection quantity on stabilization of screened soil. In case of aerobic bioreactors, the decomposition of organics in screened soil was higher than anaerobic bioreactor. According to the results of landfill gas and soil respiration test, the air injection quantity of 5 PV/day was most efficient in stabilization of screened soil.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.241-246
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• 2004

We studied field observation and countermeasure about the effluent of sediment and nutrient materials on the Okinawa Ishigaki Coast according rainy season. though this observation, we found out the analysis of outflow topography, intensity of rainfall and effects on the tide, the property of effluent materials etc. The sediment and nutrient concentration of the Okinawa Ishigaki coast are different on the regional sites according to vary with time variation of intensity of rainfall and the ebb and flow. We could confirm to vary with utilized waterways land area and distribution of surrounding vegetation.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.111-118
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• 2008

Riparian buffer zone prevents sediment entry into drainage channels or as a protection from runoff and wind erosion. However, Studies about its removing effect according to Riparian buffer zone are shorted now. In this study, using the SWAT model, Byongseong watershed is built on the Arcview GIS. Using the function of the filter strip in SWAT model, it is also examined about the variation of sediment yield. As a simulation result, the case of constructing riparian buffer zones at subbasins near the outlet shows generally high efficiency on removing sediment yield. In addition, according to the scenario analysis of changing riparian buffer zone width, it is thought that 5-10m riparian buffer zone width is the highest efficiency on removing sediment yields generated from Byeongseong watershed.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.435-438
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• 2008

본 연구에서는 최근 집중호우로 인해 탁수문제가 심각한 소양강 유역의 효과적인 탁수 관리를 위한 SWAT 모형 구축 및 유역의 시공간 토사유실 분석을 실시하였다. 검보정된 SWAT 모형을 이용하여 소유역별 부유사 발생량을 분석한 결과 조항천, 영실천/북천 상류, 인북천 상류 유역(서쪽) 등에서 연간 10톤/ha이 상의 부유사가 발생하여 소양강댐 유역에서의 탁수유발에 직접적인 영향을 미치는 것으로 나타났으며, 어론천, 자운천 등은 연간 6톤/ha이상의 부유사 발생이 예측되었다. 특히 내린천의 최상류 두 유역인 조항천과 주운천 유역에서 발생하는 부유사는 소양강 전체 유역에서 발생하는 부유사의 13.6%를 차지하는 것으로 나타나 이 유역들에 대한 토사유실 저감대책이 필요하다고 판단된다. 한편 유역에서 발생하는 부유사량의 시간별 특성을 알아보기 위하여 댐 유입부에 유입되는 부유사량의 분포를 분석한 결과, 최근 6년간 발생한 부유사량을 연도별로 살펴보면 2003년에 최고 약 1,200,000톤이 댐으로 유입되는 것으로 나타났으며, 2005년도에 최저 40,000톤이 유입된 것으로 분석되었다. 본 연구결과는 향후 각 소유역별로 탁수를 유발하는 토사 유실량 평가, 유역의 토사유실 저감대책 효과분석 및 저수지 모형과의 연계를 통한 유입된 탁수의 효율적인 관리 대책 수립에 이용될 것이다.

• Journal of Navigation and Port Research
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• v.29 no.1 s.97
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• pp.113-118
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• 2005

We studied field observation and countermeasure about the effluent of sediment and nutrient materials on the Okinawa Ishigaki Coast according rainy season though this observation, we found out the analysis of outflow topography, intensity of rainfall and effects on the tide, the property of effluent materials ete. The sediment and nutrient concentration of the Okinawa Ishigaki coast are different on the regional sites according to vary with time variation of intensity of rainfall and the ebb and flow. We could confirm to vary with utilized waterways land area and distribution of surrounding vegetation.