• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.19-19
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• 2019

토양수분은 지표수가 증발, 유출, 침투되는 과정에 중요한 역할을 하는 수문 인자로, 수문학적인 관점에서 물 순환을 이해하는 데 필수적인 요소이다. 그럼에도 불구하고 토양 내 수분을 측정하는 데 어려움이 많아 국내에서는 토양수분의 지속적인 관측을 위한 관측소 운영이 원활하게 이루어지지 않고 있으며, 주로 유전율식 계측 방식을 통해 지점 기반의 토양수분 자료를 생산하는데 그치고 있다. 최근 발사된 토양수분 위성인 SMAP (Soil Moisture Active Passive)을 비롯한 위성기반의 토양수분 자료와 융합하여 사용하기 위해서는 지점에서의 토양수분 네트워크가 우선적으로 구축되어야 하나, 관측소의 수도 부족할 뿐 아니라, 지형이 복잡하고 산지가 많은 한반도에서는 점 단위의 토양수분 자료의 공간적 대표성이 부족하여 활용에 어려움이 많다. 따라서 본 연구에서는 운영중인 지점 기반의 토양수분 관측소의 FDR (Frequency Domain Reflectometry), TDR (Time Domain Reflectometry) 센서를 함께 활용하여 산악지형에서의 Cosmic-ray 기반 토양수분자료를 생산하고자 한다. 산악지형에서의 Cosmic-ray 센서는 토양 유기물과 식생 차단 등에 의한 영향이 많으므로 평지에서 토양수분을 산정하기 위한 교정 함수들의 비교 및 평가를 실시하였다. 일반적으로 평지에서 활용되는 교정 함수들은 강우에 따른 토양수분의 거동을 잘 나타내고 있는 것으로 확인되었으나, 갑작스러운 강우로 인한 식생 차단과 토양 유기물의 영향이 커지는 경우 토양수분의 급격한 변동성을 표현하기에는 한계가 있는 것으로 나타났다. 이러한 연구를 기반으로 산악지형에서 Cosmic-ray 센서에 영향을 미치는 인자들을 분석할 수 있으며, 추후 산악지형에서 지역 규모의 토양수분을 관측할 수 있는 관측소를 구축하는데 활용될 것으로 기대된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3723-3728
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• 2011

This study investigated the friction behaviors of rock and grout through the small /large scale laboratory experiments. The small-scale laboratory tests were undertaken using a specially designed and fabricated equipments to simulate the contact surface of rock. In calibration chamber test, a artificial rock mass was prepared in soil container to measure the tensile resistance of grout. Test condition includes the grouting method of pressure involvement. The results of the tests show that the pressure grouting increases the frictional resistance significantly.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.628-635
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• 2008

A series of cone penetration tests in large calibration chamber were performed to investigate the effect of cementation level, relative density and vertical confining stress on cone resistance. From the experimental results, it was observed that the cone resistance is increased with increasing gypsum content, relative density, and confining stress. The increasing ratio on cone resistance of cemented sand compared with that of uncemented sand, that is IR($q_c$), was increased with increasing gypsum content and relative density, whereas it was decreased as the vertical confining stress increases. It was also observed that the cementation of granular soil influences the behavior of ground at low level of confining stress and its effect is diminished with depth.

• Journal of the Korean Geotechnical Society
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• v.30 no.8
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• pp.5-11
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• 2014

The objective of this paper is to develop a rational reliability analysis procedure for the LRFD design provisions of bridge substructures. A bridge abutments is considered in this study. The reliability analysis is applied to determine the relationship between the major design parameters for bridge abutment and reliability index. The considered load components include dead load, vertical and horizontal earth pressure, earth surcharge, and vehicle live load. Several limit states are considered: foundation bearing capacity, sliding, and overturning. The analysis results show that the most important parameter in the reliability analysis is the effective stress friction angle of the soil. The reliability indices are calculated using Monte Carlo simulations for a selected bridge abutment. The results of the sensitivity analysis indicate that reliability index is most sensitive with regard to resistance factor and horizontal earth pressure factor.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.49-49
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• 2016

The impact of land cover changes on streamflow of the Akaki catchment will be assessed using Soil and Water Assessment Tool (SWAT) model. The study will analyze the historical land cover changes (1993 to 2016) that have taken place in the catchment and its effect on the streamflow of the study area. Arc GIS will be used to analysis the satellite images obtained from the United States Geological Survey (USGS). To investigate the impact of land cover change on streamflow the model set up will be done using readily available spatial and temporal data, and calibrated against measured discharge. Two third of the data will be used for model calibration (1993?2000) and the remaining one-third for model validation (2001?2004). Model performance will be evaluated by using Nash and Sutcliff efficiency (NS) and coefficient of determination (R2). The calibrated model will be used to assess two land cover change (2002 and 2016) scenarios and its likely impacts of land use changes on the runoff will be quantified. The evaluation of the model response to these changes on streamflow will be presented properly. The study will contribute a lot to understand land use and land cover change on streamflow. This enhances the ability of stakeholder to implement sound policies to minimize undesirable future impacts and management alternatives which have a significant role in future flood control of the study area.

• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.101-110
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• 2007

In order to investigate the effect of the pile shape on the bearing capacity of non-displacement piles, a series of model pile load tests were performed using a calibration chamber and three model piles with different shape. Results of the model tests showed that the bearing capacity of tapered piles was affected by its taper angle as well as the stress states and relative density of soil. Based on the results of model pile load tests, a new design equation for estimation of the bearing capacity of non-displacement piles was proposed, and it takes into account the effect of the taper angles on the bearing capacity of non-displacement piles.

• Journal of the Korean Geotechnical Society
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• v.40 no.2
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• pp.115-123
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• 2024

Stress is an invisible physical quantity, necessitating the use of earth pressure cells for its measurement within theground. Traditional strain-gauge type earth pressure cells, due to their rigidity, can distribute stress within the ground and subsequently affect the accuracy of earth pressure measurements. In contrast, force sensing resistors are thin and flexible, enabling the minimization of stress disturbance when measuring stress within the ground. This study developed a system that utilizes force sensing resistors to measure ground stress. It involved constructing a soil chamber for calibrating the force sensing resistors, assessing the variability of measurements from resistors embedded in sand ground, and verifying the attachment of pucks to the sensing area of the resistors.

• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.37-53
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• 2008

This study has developed a water balance model for the catchment of Byungchun river using a BROOK90 4.4e physical deterministic water balance model with the long-term meterological data and stream run off data obtained from the basin of Byungchun river in Korea. It is intended that the validation model with calibrated model fitting parameter can build a long-term water balance plan for a period when meterological data are available but stream runoff data are not. Results of this study have satisfied the first expectation as an experiment for water balance modeling since measured stream runoff data have turned out to be very similar to simulated stream runoff data. Through the confirmation of model fitting parameters and validated simulation, water balance for the period of 1998 to 2006 has been restored. Unless the conditions of geomophology, vegetation, soil and land use change, meterological data alone can produce various hydrometeorological data related to stream runoff amount, soil water amount, and evapotranspiration. This study opens up a new horizon in restoring water balance in the past as well planning water balance in the present. The obtained results from this study are expected to be used in predicting future water balance in the wake of the changes in climate and vegetation in Korea.

• KCID journal
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• v.14 no.2
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• pp.207-213
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• 2007

For sustainable development at a watershed, environment friendly site-specific management practices need to be developed and implemented. The soil and Water Assessment Tool(SWAT)model has been world-wide used to estimate stream flow, sediment, and nonpoint source pollutant loads, and effects on water quality of different management practices. In this study, the SWAT model was used to estimate the flow resources at Hwacheon areas using Digital Elevation Model(DEM),Land use, precipitation ,wind ,maximum and minimum temperature, solar radiation, humidity of watershed The R2 value and EI value for the comparison of SWAT estimated flow and measured flow were 0.87 and 0.67 respectively for calibration period, and the R2 value and E1 value for validation were 0.75 and 0.67 respectively. The comparison results show what the SWAT model is applicable to simulate hydrology behaviors at this study watershed.

• Journal of Korea Water Resources Association
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• v.34 no.4
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• pp.403-411
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• 2001

This paper investigates the applicability of a modified version of TOPMODEL considering shallow subsurface storm flow in a forested mountaneous catchment. The macroporous soil structure provides a hydrological pathway for rapid runoff generation. A modified version of TOPMODEL introduces the two-storage system to analyze the hydrograph recession including rapid subsurface storm flow component. The two-month continuous hydrologic simulations of sulmachun watershed suggest that a modified version of TOPMODEL represents comprehensive and realistic flow generation mechanism comparing to those of an original version of TOPMODEL. The results of parameter calibration with Monte-Carlo method indicate a modified version of TOPMODEL produces a set of physically meaningful parameters.