• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.660-663
• /
• 2008

방수로는 본류의 첨두홍수량을 분담하여 대상 지역의 홍수피해가능성을 줄이기 위해서 도입되는 구조적 홍수방어대책의 하나로 특히 도시화로 인하여 기존 하천 유역의 저류 능력이 감소하여 홍수 시 유출량이 증가함에 따라 방수로의 필요성은 점차 늘어나고 있다. 외국의 경우에는 이미 대표적인 구조적 홍수방어대책으로 활용되어 그 효과가 이미 확인되어 있다. 방수로로 분담되는 유량은 일반적으로 방수로 유입부에 설치되어 있는 횡월류위어의 월류량을 정확히 산정함으로써 알 수 있다. 따라서 방수로의 홍수방어능력을 알기위해서는 이러한 유입부 횡월류위어의 월류량을 정확히 평가하는 것이 중요하다. 횡월류위어의 형태는 여러 가지가 있지만 가장 기본적인 형태로 예연위어 형태와 광정위어 형태가 있다. 본 연구에서는 그 중에서 광정횡월류위어(broad-crested side weir)을 대상으로 실제 하도와 유사한 흐름 조건을 가지도록 상대적으로 작은 횡월류위어길이(L)와 본류 폭(B) 비(L/B)를 가지는 실험 수로를 이용하여 광정횡월류위어에 대한 실험을 수행한 후 유량 계수를 산정하여 본류 흐름 조건 및 횡월류위어 제원 변화에 따른 영향을 검토하였다. 광정횡월류위어에서의 유량계수도 기본적으로 예연횡월류위어와 동일한 방식을 이용하여 검토할 수 있으며, 동일한 주요 영향 변수를 포함하지만, 위어 폭 W가 횡월류위어의 월류 유량과 본류 유황에 영향을 미치게 된다. 따라서 본 연구에서는 광정횡월류위어의 특성에 따른 산정된 유량계수의 변화에 초점을 두어 분석을 수행하였다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.3B
• /
• pp.265-276
• /
• 2011

Precipitation data and groundwater level data were collected for Korean peninsular and Jeju island. The relationship between precipitation and groundwater level and the correlation between the moving average of precipitation and goundwater level were analyzed. Critical infiltration, which is the spatially averaged maximum daily infiltration depth over interested region, is considered when the precipitation data was modified for moving average process and correlation between the moving average of modified precipitation and groundwater level. High correlation regions, which have greater than 0.6 correlation coefficients, were selected after the analysis with ciritical infiltration. Twenty-six regions were selected for high correlation regions. If we divide the regions by administrative district, there are nine regions for Gyungsang-Do, five regions for Chunchung-Do, four regions for Gyunggi-Do and Gangwon-Do, three regions for Jolla-Do, and one region for Jeju island. The groundwater level data for high correlation regions shows obvious response after precipitation event and there are few cases with abrupt change in groundwater level without precipitation-related event.

• Journal of agriculture & life science
• /
• v.43 no.5
• /
• pp.47-55
• /
• 2009

This study analyzes the correlation between noise and the size of urban forests. Under the assumption that the main cause of the noise m the city is the population density, the size of urban forests per capita and the ratio of urban forests with respect to the size of urban per 100 thousand persons are used for the calculation of correlations with noise. The results of the calculations of Pearson's and Spearman's correlation coefficients indicate that the increase in the size of urban forests has a significant effects in reducing the day-time as well as night-time noise for most regions in the cities. The size of urban forests within public parks has a significantly negative correlation with the noise. However, calculated correlation coefficients imply the increase in the size of total urban forests is more effective in reducing the noise than the increase in the urban forests in public parks.

• Journal of the Korean Geosynthetics Society
• /
• v.10 no.3
• /
• pp.25-32
• /
• 2011

The matric suction and volumetric water content of dredging soils obtained from Saemangeum area were measured by the automated Soil-Water Characteristic Curve (SWCC) apparatus under both drying and wetting conditions. Based on the test result, SWCCs of the dredging soils were estimated by the van Genuchten(1980) model. The matric suction of drying process is larger than that of wetting process at a same effective degree of saturation. The suction stresses for various matirc suctions were estimated using Lu and Likos(2006) model and the Suction Stress Characteristic Curves (SSCC) were predicted using the independent parameter of SWCC. The suction stress of drying path was increased and decreased, while the suction stress of wetting path was continuously decreased with increasing the effective degree. Also, the suction stress of drying path is larger than that of wetting path at a same effective degree of saturation. The Hydraulic Conductivity Function(HCF) was also predicted by the van Genuchten(1980) model. The hydraulic conductivity was increased with increasing the volumetric water content. The hydraulic conductivity of drying path is larger than that of wetting path at a same matric suction. According to the results of SWCCs and SSCCs, the hysteresis phenomenon of suction stress or matric suction during both drying and wetting paths was occurred. The main reason of hysteresis phenomenon is a ink bottle effect of water among soil particles.

• Journal of Korea Water Resources Association
• /
• v.33 no.1
• /
• pp.133-142
• /
• 2000

Series of tests were carried out to study permeability characteristics of unsaturated soils. The weathered soils taken from Inju, Sungwhan, and Kuri, were selected to have different amount of fine grained soils in order to find a possible correlation between the unsaturated permeability behavior and fine grained soils contents. Measurements of permeability for unsaturated soils were performed with a newly developed apparatus, which modeled after Klute's apparatus(1965a). The apparatus was designed to measure volumetric water content and permeability by applying incremental suction pressure. Permeability and volumetric water content of unsaturated soils generally decreased as density of the soil increased. The relationship between volumetric water content and permeability was not related to the fine grained soils contents because the plots scattered widely. By comparing volumetric water content with permeability, empirical parameters A and B could be determined, which made to be possible to predict unsaturated permeability from soil-moisture characteristics.

• Journal of the Korean Geosynthetics Society
• /
• v.21 no.1
• /
• pp.23-32
• /
• 2022

This study is conducted to minimize the problems caused by the difference between the settlement and settlement time of the one-dimensional consolidation analysis by the Terzaghi's consolidation theory, which is generally used in domestic soft soil design, from the settlement and settlement time measured at the field site. Consolidation-time factor considering the field site characteristics can be determined using the relationship among the degree of consolidation, settlement time, and time factor, the time-settlement curve measured at the field is reverse- analysis using a numerical-analysis technique to reproduce the same consolidation behavior as in the field. Time-settlement and time-excessive pore water pressure data when the same consolidation behavior as the site is reproduced Consolidation-time factor of the soil of Songsan Green City by settlement and excess pore water pressure was calculated using the settlement and excess pore water pressure for each settlement time. If the results of this study use the Terzaghi consolidation-time factor, which does not consider the consolidation characteristics of the soft ground target area, it is difficult to determine the end time of the soft ground during construction. It is necessary to use the established settlement-time factor.

• Economic and Environmental Geology
• /
• v.35 no.6
• /
• pp.509-521
• /
• 2002

The purpose of this study is to find out geochemical characteristics of stream sediments which are good indicator of geochemical hazard valuation and water in primary channels of the Jangheung area. We separated three groups which were granitoid area, granite gneiss area and tuffeous area by petrological properties. Physical and chemical characteristics of stream water such as temperature, pH, and EC were measured in the field between 1999 and 2001 and stream sediments samples were collected from April to May in 1999. For the chemical analysis of stream sediments samples, XRF, ICP-AES and NAA were used. The contents of the major elements had a similar contents in three groups and those of rare earth elements in granite gneiss area were lower value than those of other two groups. Zn and Cu were higher value than the other toxic elements. Through the enrichment factor and enrichment index features of the elements, we knew that $Fe_2O_3$, MgO, $TiO_2$, MnO and Eu, Yb of the tuffeous area samples and Co, Cr, Zn were enriched.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.2 no.1
• /
• pp.53-62
• /
• 1982

An effort of preliminary type has been made to develope a practical method for the waterway area determination of a drainage outlet in rural or agricultural areas. The Seoul meteorological station was selected as tile index station, and the maximum rainfalls-duration-frequency (R-D-F) relation of short-time intense rainfalls was first established. A frequency analysis of the daily rainfalls for the 75 stations selected throughout the country resulted the 50-year daily rainfall for each station. The rainfall factor, which is defined here as the ration of 50-year daily rainfalls of individual station and the index station, was determined for the 8 climatological regions divided in this study. Following the US SCS method the runoff number of a watershed was given based on the soil type, land-use pattern, and the surface treatment. With this runoff number and the R-D-F relationship the runoff factors for the index station were computed and hence a nomogram could be drawn which makes it possible to determine the runoff factor for a given rainfall number and a rainfall of specific duration and frequency. With this done, the potential runoff of a watershed for a given rainfall duration could be calculated, based on the unit hydrograph theory, by multiplying the rainfall factor, the runoff factor, and the drainage area of the watershed under consideration. Then, the maximum runoff potential was determined by varying the rainfall duration and finding out the duration which results the peak discharge of a gived return period.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.10
• /
• pp.49-60
• /
• 2010

Unsaturated permeability function is an important factor in the design and analysis of various unsaturated soil structures. Generally the permeability characteristics decrease as the mat ric suction increases and the trend is similar to water retention characteristics of a soil. The permeability of unsaturated soils can be obtained directly by laboratory tests or indirectly by estimation methods from other soil properties. For unsaturated soils sampled from 7 areas in KOREA, SWCCs and unsaturated permeability functions were obtained by experimental tests. The unsaturated permeability results were also compared with the unsaturated permeability functions derived from the SWCCs theoretically. However, the current estimation models of unsaturated permeability function did not express the unsaturated permeability characteristics. Therefore, the FXK-M permeability function was modified to predict more accurate permeability functions for Korean weathered soils using a correction factor that can be calculated from the air-entry value of SWCC. The new estimation model resulted in good agreements for all tested soils.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.459-459
• /
• 2012

본 연구에서는 우리나라의 건설현장에서 발생하는 안전사고 발생 특성과 강수특성 변화의 연관성을 분석하였다. 대상기간 2000년부터 2010년까지 지역별 건설 산업현장에서의 사고발생 건수(한국산업안전보건공단) 자료와 같은 시기 지역별 강수량 자료(기상청 지상관측지점)를 사용하여 강수량의 거동과 건설현장 사고발생 건수의 거동 사이의 상관성을 분석하였다. 건설현장 사고사례의 사고형태 중 부상자와 사망자 정보를 사용하였으며 지역의 구분은 특별시, 광역시 및 도 단위로 구분하여 분석하였다. 분석결과 전반적으로 연간 강수량의 증가 추세와 유사하게 전체 건설현장 안전사고의 발생건수가 증가하는 추세를 보이며, 지역별로 강수량의 증감 거동과 유사한 사고발생의 빈도의 증감거동을 보였다. 우리나라의 평균 월강수량과 월별 건설 안전사고 발생건수는 0.8의 선형상관성을 가지며 지역별 분석에서는 섬지역인 제주도가 가장 높은 상관계수 0.9를 나타냈고, 서울특별시 0.7, 대구광역시 0.7, 광주광역시 0.7, 부산광역시 0.5, 인천광역시 0.5, 대전광역시 0.4의 상관관계 순으로 나타났다. 강수변화에 따른 지역, 계절, 월별 강수-건설재해 상관성을 분석 제시하였다. 장마철인 7~8월에는 봄철인 3월~5월에 비해 강수량의 증가뿐만 아니라 21.16%의 사고 발생건수 증가가 나타났으며 우리나라의 강수특성 중 기후변화로 인하여 태풍의 영향이 많았던 시기의 사고발생의 특성을 정량적으로 분석하였다. 특히 2002년 태풍 '루사'와 2003년 태풍 '매미' 발생 시 산업현장의 재해 발생이 많이 있었던 것으로 조사 되었는데, 그 이유로는 산업현장에 태풍의 영향으로 감전사고 발생률이 2배가량 증가하며, 구조물과 사면이 무너져 내리는 등 사고가 빈번히 발생하면서 재해발생률이 더 증가하였다. 이처럼 기후변화에 따른 강수특성 변화로 건설 산업현장은 사고의 위험에 더욱 노출되고 있으므로 이에 대한 지역적 특성 분석과 대책 수립이 요구된다.