• 한국지반신소재학회논문집
• /
• 제10권4호
• /
• pp.105-112
• /
• 2011

본 논문에서는 지속하중이 작용하는 보강토 구조물의 시간의존적 장기거동에 관한 수치 모델링 기법을 다루었다. 먼저 Power Law 기반의 크리프 모델을 이용하여 지오그리드와 뒤채움흙의 크리프 거동의 모델링에 대한 적용성을 검토 하였으며 나아가 보강토 교대 구조물의 장기 거동에 대한 해석에 적용하였다. 그 결과 Power Law 기반의 크리프 모델은 지오그리드와 뒤채움흙으로 구성되는 보강토 교대 구조물에 지속하중 작용시 발생하는 크리프 변형을 적절히 모사할 수 있는 것으로 검토되었으며 크리프 변형이 발생할 수 있는 뒤채움흙을 사용하는 경우 교대 벽체 및 상판기초에 허용치를 초과하는 변위가 발생할 수 있는 것으로 검토되었다. 본 연구에서 얻어진 결과의 실무적 적용 방안에 대한 내용을 기술하였다.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 1999년도 정기총회 및 춘계 공동 학술발표회
• /
• pp.74-74
• /
• 1999

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제10권4호
• /
• pp.13-17
• /
• 2005

암모늄의 질산화 반응, 질소산화물의 탈질 반응, 그리고 유기물의 산화반응을 고려한 SAT 모델링 시스템에 대해서, 현장조건의 변화에 따른 모델 결과를 비교하기 위해 6가지 모델 조건에 대한 가상의 수직 2차원상 모델 시뮬레이션을 하였다. 시뮬레이션 조건에서 수리전도도, 주입수 주입율, 지표 피복 여부, 그리고 운영 계획과 같은 4가지 영향 인자들이 고려되었다. 시뮬레이션 결과, 모든 조건에서 모델 개발 과정에서 고려한 반응 영향들이 잘 모사되었다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제26권6호
• /
• pp.74-81
• /
• 2021

A simple and efficient scheme is presented that attempts to implement the site-specific denitrification rate in the reactive transport modeling for the nitrate in groundwater. A series of correlation analyses were conducted using 133 datasets obtained from different nitrate-contaminated sites to find the empirical relationships between denitrification rates and various subsurface properties. Based on Pearson's correlation analysis, the soil organic carbon concentrations showed a statistically significant correlation (r = 0.75, p < 0.05) with the denitrification rates. A linear regression was performed, which could be utilized to effectively determine the site-specific denitrification rate based on the soil organic carbon concentration of a site. The proposed method is expected to effectively replace the conventional methods which either were too complicated for practical application or impose large uncertainties that might end up with unreliable results.

• Geomechanics and Engineering
• /
• 제17권3호
• /
• pp.287-294
• /
• 2019

The finite element method (FEM) is widely used to evaluate the seismic performance of pile-supported buildings. However, there are problems associated with modeling the pile end resistance using the FEM, such as the dependence on the mesh size. This paper proposes a new method of modeling around the pile tip to avoid the mesh size effect in two-dimensional (2D) analyses. Specifically, we consider the area of influence around the pile tip as an artificial constraint on the behavior of the soil. We explain the problems with existing methods of modeling the pile tip. We then conduct a three-dimensional (3D) analysis of a pile in various soil conditions to evaluate the area of influence of the soil around the pile tip. The analysis results show that the normalized area of influence extends approximately 2.5 times the diameter of the pile below the pile tip. Finally, we propose a new method for modeling pile foundations with artificial constraints on the nodal points within the area of influence. The proposed model is expected to be useful in the practical seismic design of pile-supported buildings via a 2D analysis.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제10권3호
• /
• pp.9-15
• /
• 2005

토양/대수층 처리(Soil Aquifer Treatment, SAT)는 하수처리장으로부터의 2차 또는 3차 처리수를 대수층으로 침투시켜, 토양 매질에서 일어나는 물리적/생화학적 반응에 의해 재처리하는 용수 재이용 기술이다. SAT에서의 주요 관심 대상은 유기물과 질소화합물의 제거와 이송에 있다. 본 연구에서는 암모늄의 질산화 반응, 질소산회물의 탈질 반응, 그리고 유기물의 산화반응을 고려하여 SAT에서 일어나는 반응 메커니즘을 규명하고 이를 지하수 흐름과 이송 모렐 에 접목시킴으로써 SAT 모델링 시스템을 구현하고자 하였다. 실험실 일차원 불포화 토양 컬럼 실험을 통한 모델 검증에서 암모늄, 질산성 질소, DOC, 용존산소 모두 일정한 농도 범위 안에서 일치하였다. 모델 변수에 대한 민감도 분석에서, 암모늄 분배계수는 유출부의 암모늄 농도에, 용존산소 저해상수는 유출부의 유기물 농도에, 그리고 미생물 감쇄계수는 유출부의 용존산소 농도에 영향을 주었다.

• 한국농공학회논문집
• /
• 제49권2호
• /
• pp.49-60
• /
• 2007

The alpine agricultural activities are usually performed at higher and steep areas in nature. Thus, significant amounts of soil erosion are occurring compared with those from other areas. Thus, the soil erosion induced environmental impacts in these areas are getting greater. The Doam watershed is located at alpine areas and it has been well known that the agricultural activities in the watershed are causing accelerated soil erosion and water quality degradations. Many modeling approaches were employed to solve soil erosion and water quality issues. In this study, the Soil and Water Assessment Tool (SWAT) model was utilized to simulate the hydrologic and sediment behaviors in the Doam watershed. In many previous modeling studies, the digital soil map and its corresponding soil properties were used without modification to reflect soil conditioning at many agricultural fields of the Doam watershed. Thus, the soil sample was taken at the agricultural field within the Doam watershed and analyzed for its physical properties. In this study, the digital topsoil properties in the agricultural fields within the Doam watershed were replaced with the soil properties for reconditioned soil analyzed in this study to simulate the impacts of using soil properties for reconditioned soil in hydrologic and sediment modeling at the Doam watershed using the SWAT model. The hydrologic component of the SWAT model was calibrated and validated for measured flow data from 2002 to 2003. The $R^2$ value was 0.79 and the EI value was 0.53 for weekly simulated data. The calibrated model parameters were used for hydrologic component validation and the $R^2$ value was 0.86 and the EI value was 0.74 for weekly data. For sediment comparison, the $R^2$ value was 0.67 and the EI value was 0.59. These statistics improved with the use of soil properties of the reconditioned soil in the field compared with the results obtained without considering soil reconditioning. The simulated sediment amounts with and without considering the soil properties of the reconditioned soil were 284,813 ton and 158,369 ton, respectively. This result indicates that there could be approximately 79% of errors in estimated sediment yield at the Doam watershed, although the model comparison with the measured data gave similar satisfactory statistics with and without considering soil properties from the reconditioned soil.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
• /
• pp.443-450
• /
• 2000

In this study a numerical method for soil-pile interaction analysis buried in multi-layered half planes is presented in frequency domain using FE-BE coupling. The total soil-pile interaction system is divided into two parts so called far field and near field beam elements are used for modeling a pile and coupled with plain strain elements for soil modeling. Boundary element formulation using the multi-layered dynamic fundamental solution is adopted to the far field and coupled with near field modeled by finite elements. In order to verify the proposed soil-pile interaction analysis method the dynamic responses of a pile on multi-layered dynamic fundamental solution is adopted to the far field and coupled with near field modeled by finite elements. In order to verify the proposed soil-pile interaction analysis method the dynamic responses of a pile on multi-layered half-planes are performed and compared with experiment results. Through this developed method the dynamic response analysis of a pile buried in multi-layered half planes can be calculated effectively in frequency domain.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 1998년도 학술발표회 발표논문집
• /
• pp.65-70
• /
• 1998

Soil moisture measuring is important for irrigation scheduling of upland crops, estimation of evapotranspiration, and hydrologic modeling. Hence, the comparative study was implemented for the soil moisture measuring instruments, Neutron probe and TDR with soil sampling methods, and the result was represented.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.189-198
• /
• 2006

This paper concerns the finite element (FE) modeling approach for NATM tunneling in water bearing ground within the framework of stress-pore pressure coupled analysis. Fundamental interaction mechanism of ground and groundwater lowering was first examined and a number of influencing factors on the results of coupled FE analysis were identified. A parametric study was then conducted on the influencing factors such as soil-water characteristics, location of hydraulic boundary conditions, the way of modeling drainage flow, among others. The results indicate that the soil-water characteristics plays the most important role in the tunneling-induced settlement characteristics. Based on the results, modeling guidelines were suggested for stress-pore prssure coupled finite element modeling of NATM tunneling.