• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.17 no.2
• /
• pp.235-243
• /
• 2019

Radioactive materials are released into the air and deposited on the surface soil after a nuclear accident. Radionuclides deposited in soil are transported by precipitation to nearby environments and contaminate the surface water system. Basic data on surface watershed and soil erosion models have been collected and analyzed to evaluate the behavior of radionuclides deposited on surface soil after a nuclear accident. Data acquisition and analysis in aquatic environment were performed to investigate the physical characteristics and variation of biota in rivers and lakes of the Nakdong river area near the Wolsong nuclear power plant. For these purposes, a digital map, and hydrological, water quality and biota data were gathered and a systematic database (DB) was constructed in connection with them. Constructed aquatic DB will be supplied and used in surface watershed and soil erosion models for investigation of long-term movement of radionuclides in adsorptive form in surface soil. Finally, basic data and established models will be utilized for general radiological impact assessment in aquatic environment.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.240-240
• /
• 2020

강우 시 우수관로 내부의 수리 거동(유속, 수위)에 영향을 미치는 대표적인 매개변수는 관로의 조도계수와 손실계수 등이 있다. 이 중 조도계수는 관로 내부의 퇴적 및 협잡물로 인한 조도높이 변화에 따른 관로 내의 수리학적 거동을 평가할 수 있는 매개변수이며 손실계수는 관로의 확대, 축소, 만곡 등에 의한 에너지 감쇄 효과에 따른 관로 내 수리학적 변화를 평가할 수 있는 매개변수이다. 본 연구에서는 서울시 주요 배수구역에 대해 관로 조도계수 및 손실계수 변화에 따른 수위, 유속 변동성을 SWMM으로 분석하였다. 연구에 적용한 대상 배수구역은 반포 02 (방배1), 안양천 13 (봉천1), 성내 05 (길동), 안양천 11(신림4), 반포 03 (방배2), 안양천 01 (오류1), 성내 03 (천호)로 총 7개 배수구역이다. 모형수행을 위한 조건으로 조도계수는 0.015 ~ 0.120 구간에 대해 0.003 단위로 증가시키며 총 12개 CASE를 적용하였으며 손실계수는 0.0 ~ 0.5 구간에 대해 0.1 단위로 총 6개 CASE를 적용하였다. 관로 수리특성에 따른 수심, 유속의 변화량 분석 결과는 관로 및 유역의 크기별로 변화의 폭이 매우 크므로 상자-수염그림(Box-whisker plot) 이용하여 중간값의 변화 정도를 검토하였다. 조도계수 증가에 따른 수심증가, 유속 감소치의 중간값을 분석한 결과 조도계수가 0.013에서 0.034로 증가 시 수심은 40.6% 증가하고 유속은 47.4% 감소하는 것으로 검토되었다(그림 1, 2). 한편, 손실계수 증가에 따른 수심증가, 유속 감소치의 중간값을 분석한 결과 조도계수가 0.0에서 1.6으로 증가시 수심은 15.7% 증가하고 유속은 15.0% 감소하는 것으로 검토되었다. 이상과 같은 연구의 성과는 우수관로 내부의 다양한 여건 변화가 강우 시 관로 내 수리특성에 미치는 영향을 판단하기 위한 기초 자료로 활용할 수 있으며 향후, 우수관로 모니터링 결과와 연계하여 유지관리 방안 수립에 활용할 수 있을 것으로 판단된다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.2A
• /
• pp.339-349
• /
• 2006

The purpose of this study is to investigate the seismic behavior of circular reinforced concrete bridge piers with confinement steel and to provide the data for developing improved seismic design criteria. Fourteen circular reinforced concrete bridge piers were tested under a constant axial load and a cyclically reversed horizontal load. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. In the companion paper, the proposed numerical method for the seismic performance assessment of circular reinforced concrete bridge piers with confinement steel is verified by comparison with experimental results.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.3
• /
• pp.243-254
• /
• 2009

Tunnel problems relate to pore water pressure generally occur due to the restriction of groundwater flow into the tunnel which is generally caused by the deterioration of drainage systems. Previous studies have identified the problem as combined mechanical and hydraulic interaction occasions. In this study, detrimental effects of pore water pressure on the lining were investigated using the finite element method considering deterioration of the drainage system. Particularly, double-lined linings with drain-holes are considered. Deterioration of drainage system is represented as blockages of drain-holes. It is identified that the secondary lining ran be influenced by the deterioration of drainage system. It is shown that a tunnel with all drain-holes blocked moved upward, and unbalanced drain-hole blocking may result in torsional behavior of the tunnel which causes significant damages to the secondary linings.

• Journal of the Korean GEO-environmental Society
• /
• v.25 no.7
• /
• pp.29-34
• /
• 2024

Frost heave is one of the significant engineering characteristics of frozen ground and causes severe damages on geo-structures. Although thermo-hydro coupled analyses have been developed to predict frost heave behavior, these analyses involve excessive input parameters and have primarily been validated for frost heave in clayey soils. Frost heave mainly occurs in silty soils, which have relatively higher permeability compared to clayey soils, necessitating careful attention. This study introduces empirical models and verifies their reliability for silty soils. By using the validated model, the correlation of key input parameters is derived, which is expected to enhance the applicability of thermal-mechanical analysis for geo-structures on frozen ground in the future.

• Tunnel and Underground Space
• /
• v.28 no.6
• /
• pp.670-691
• /
• 2018

This study presents the research results of the BMT(Benchmark Model Test) simulations of the DECOVALEX-2019 project Task B. Task B named 'Fault slip modelling' is aiming at developing a numerical method to predict fault reactivation and the coupled hydro-mechanical behavior of fault. BMT scenario simulations of Task B were conducted to improve each numerical model of participating group by demonstrating the feasibility of reproducing the fault behavior induced by water injection. The BMT simulations consist of seven different conditions depending on injection pressure, fault properties and the hydro-mechanical coupling relations. TOUGH-FLAC simulator was used to reproduce the coupled hydro-mechanical process of fault slip. A coupling module to update the changes in hydrological properties and geometric features of the numerical mesh in the present study. We made modifications to the numerical model developed in Task B Step 1 to consider the changes in compressibility, Permeability and geometric features with hydraulic aperture of fault due to mechanical deformation. The effects of the storativity and transmissivity of the fault on the hydro-mechanical behavior such as the pressure distribution, injection rate, displacement and stress of the fault were examined, and the results of the previous step 1 simulation were updated using the modified numerical model. The simulation results indicate that the developed model can provide a reasonable prediction of the hydro-mechanical behavior related to fault reactivation. The numerical model will be enhanced by continuing interaction and collaboration with other research teams of DECOVALEX-2019 Task B and validated using the field experiment data in a further study.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.9 no.4
• /
• pp.34-44
• /
• 2006

Simulation models allow researchers to model large hydrological catchment for comprehensive management of the water resources and explication of the diffuse pollution processes, such as land-use changes by development plan of the region. Recently, there have been reported many researches that examine water body quality using Geographic Information System (GIS) and dynamic watershed models such as AGNPS, HSPF, SWAT that necessitate handling large amounts of data. The aim of this study is to develop a watershed based water quality estimation system for the impact assessment on stream water quality. KBASIN-HSPF, proposed in this study, provides easy data compiling for HSPF by facilitating the setup and simulation process. It also assists the spatial interpretation of point and non-point pollutant information and thiessen rainfall creation and pre and post processing for large environmental data An integration methodology of GIS and water quality model for the preprocessing geo-morphologic data was designed by coupling the data model KBASIN-HSPF interface comprises four modules: registration and modification of basic environmental information, watershed delineation generator, watershed geo-morphologic index calculator and model input file processor. KBASIN-HSPF was applied to simulate the water quality impact by variation of subbasin pollution discharge structure.

• Journal of Korea Water Resources Association
• /
• v.44 no.3
• /
• pp.199-208
• /
• 2011

The objective of this study is to develop real-time river flow forecast model by linking continuous rainfall-runoff model with ensemble Kalman filter technique. Andong dam basin is selected as study area and the model performance is evaluated for two periods, 2006. 7.1~8.18 and 2007. 8.1~9.30. The model state variables for data assimilation are defined as soil water content, basin storage and channel storage. This model is designed so as to be updated the state variables using measured inflow data at Andong dam. The analysing result from the behavior of the state variables, predicted state variable as simulated discharge is updated 74% toward measured one. Under the condition of assuming that the forecasted rainfall is equal to the measured one, the model accuracy with and without data assimilation is analyzed. The model performance of the former is better than that of the latter as much as 49.6% and 33.1% for 1 h-lead time during the evaluation period, 2006 and 2007. The real-time river flow forecast model using rainfall-runoff model linking with data assimilation process can show better forecasting result than the existing methods using rainfall-runoff model only in view of the results so far achieved.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.6 s.58
• /
• pp.192-203
• /
• 2009

In the new Seoul-Busan high speed railroad construction specially in area of city center passage the roadbed establishment is recommended the staibility for the existing subway tunnel segments of Busan subway 1st and 2nd lines regarding the appearance condition, a quality condition and the durability of the objective facility, and it evaluates the numerical analysis using MIDAS/GTS which leads the stability of the objective facility and investigatesd tunnels. Fundamental issues in tunneling under high groundwater table are discussed and the effect of groundwater on tunnel excavation was examined using a 3D stress-pore pressure coupled Finite-Element Method. Based on the results the interaction mechanism between the tunnelling and groundwater is identified. In the both of 1st and 2nd Line the maximum sinkage, unequal sinkage and the lining stress from numerical analysis are within permission and the damage degree is appearing to be disregarded. But it enforces necessary Pre-grouting in order to minimize an actual tunnel face conduct and when the tunnel is excavated it is also necessary to minimize the outflow possibility.

• Microbiology and Biotechnology Letters
• /
• v.48 no.1
• /
• pp.72-78
• /
• 2020

The dynamics of nitrogen compounds and RNA-based functional genes were characterized in the nitrification-denitrification coupling process. For the removal of residual ammonium, intermittent aeration was introduced in the denitrification reactor. N₂O production was not observed in both reactors. In both reactors, the nitrifying genes (achaeal-amoA, bacterial-amoA and hor) and denitrifying genes (narG, nirK, norB and nosZ) had a copy number of 3.92 × 10²-7.25 × 10⁵ and 2.85 × 10²-3.06 × 10⁴ per ng of DNA, respectively. These results suggest that denitrification and nitrification reactions occur in both the nitrification and denitrification reactors, respectively. Therefore, the coupling process is a promising one for the conversion of ammonium to nitrogen without generating N₂O.