• 한국농공학회논문집
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• 제46권3호
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• pp.3-14
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• 2004

A two-dimensional numerical model based on a finite volume method was formulated to solve the shallow water equations and applied for evaluating drainage characteristics at large-sized paddy fields. Manning roughness coefficient was calibrated using the observed inundating depths at drainage tests, and used for validating the model with the results from another drainage test. The simulated results were in good agreement with the observed inundating depths. The result of surface drainage showed that the longer width of the outlet was or the more the number of drainage outlet was, the shorter the drainage time was taken, and the larger the size of the field become, the longer the drainage time was taken, and the field shape had little effect on drainage time. To reduce the drainage time to 24 hours, the outlet is located lower than the elevation of the basin and small drainage ditch is constructed at the field. The results showed that the drainage time was taken short as the small drainage ditch was constructed. The comparison of drainage time as to the size of field constructed small drainage ditch showed the field, 100m ${\times}$ 200 m, can be drained in 24 hours.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.162-168
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• 2000

A two-dimensional numerical model based on a finite volume method was formulated to solve the shallow water equations and applied for evaluating irrigation and drainage characteristics at large-sized paddy fields. Manning roughness coefficient was calibrated using the observed inundating depths at drainage tests and used for validating the model with the results from irrigation and drainage test. The simulated results were in good agreement with the observed inundating depths.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.669-676
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• 2000

The estimation of consolidation rate is one of the important factors in the construction on soft clayey deposits. A number of researches are carried out to predict the consolidation behavior in field, however, most of the results show the discrepancies between the prediction and observation. This paper analyzes consolidation behavior of normally consolidated clay in K/sub o/ condition with 2-dimensional drainage by use of the numerical methods. Elastic and elastic-plastic finite element analyses are compared in terms of the dissipation of excess pore pressure. These results are also compared with Terzaghi-Rendulic's equation that is implemented by finite difference method. The consolidation time calculated by using elastic model is found to be similar to the result of Terzaghi-Rendulic's equation. The consolidation predicted by MCC model takes more time than other cases. Initial increase of excess pore pressure in radial drainage can be shown, however, this phenomenon does not have a significant effect on tile final consolidation time.

• Journal of Chest Surgery
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• 제21권2호
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• pp.366-372
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• 1988

Cardiac tamponade occurring after open heart surgery is a rare, but fatal complication necessitating urgent drainage, though postoperative pericardial effusion is common. Two-dimensional echocardiographic study provides excellent postoperative visualization of pericardial effusion. Catheter insertion guided by two-dimensional echocardiography has been used to accomplish nonoperative drainage of symptomatic postoperative pericardial effusion in 4 cases. This technique offers simplicity, safety, and cost effectiveness.

• 한국지반공학회지:지반
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• 제12권6호
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• pp.127-138
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• 1996

배수재가 설치된 연약지반의 현장거동은 3차원적인 특성을 나타낸다. 그러므로 보다 효율적인 2차원 평면변형률 수치모델을 이용하여 적절하게 해석하기 위해서는 현장지반의 3차원적인 흐름특성을 평면변형률 모델의 층류흐름으로 전환할 필요성이 있다. 본 논문에서는 배수재가 설치된 연약지반의 3차원적인 거동특성을 고려하기 위하여 등가의 효과적인 모델방법이 유한요소법에 적용되었다. 2차원 등가모델은 등가투수계수와 배수재의 강성토를 고려한 등가폭을 가진다. 제안된 등가모델을 검증하기 위하여 ABAQUS 프로그램을 이용한 3차원 압밀해석을 수행하였으며, 3차원 해석결과와 2차원 해석결과를 비교하였다. 제안된 등가모델을 적용한 2차원 평면변형률 수치해석방법은 현장지반의 3차원적인 거동특성을 비교적 정확히 예측할 수 있다.

• 한국농공학회논문집
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• 제56권2호
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• pp.1-9
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• 2014

A modeling system is constructed by integrating an one-dimensional unsteady flow simulation model and a hydrologic model to simulate flood flows in drainage channel networks of paddy field districts. The modeling system's applicability is validated by simulating flood discharges from a paddy field district, which consists of nine paddy fields and one drainage channel. The simulation results are in good agreement with the observed. Particularly, in the verification stage, the relative errors of peak flows and peak depths between the observed and simulated hydrographs range 8.96 to 10.26 % and -10.26 to 2.97 %, respectively. The modeling system's capability is compared with that of a water balance equation-based model; it is revealed that the modeling system's accuracy is superior to the other model. In addition, the simulations of flood discharges from large-sized paddy fields through drainage channels show that the flood discharge patterns are affected by drainage outlet management for paddy fields and physical characteristics of the drainage channels. Finally, it is concluded that to efficiently design drainage channel networks, it is necessary to analyze the results from simulating flood discharges of the drainage channel networks according to their physical characteristics and connectivities.

• Geomechanics and Engineering
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• 제9권5호
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• pp.669-685
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• 2015

A three-dimensional elastoplastic constitutive model, also known as a UH model (Yao et al. 2009), was developed to describe the stress-strain relationship for normally consolidated and over-consolidated soils. In this paper, an acoustic tensor and discriminator of bifurcation for the UH model are derived for the strain localization of saturated clays under undrained and fully and partially drained conditions. Analytical analysis is performed to illustrate the points of bifurcation for the UH model with different three-dimensional stress paths. Numerical analyses of cubic specimens for the bifurcation of saturated clays under undrained and fully and partially drained conditions are conducted using ABAQUS with the UH model. Analytical and numerical analyses show the similar bifurcation behaviour of overconsolidated clays in three-dimensional stress states and various drainage conditions. The results of analytical and numerical analyses show that (1) the occurrence of bifurcation is dependent on the stress path and drainage condition; and (2) bifurcation can appear in either a strain-hardening or strain-softening regime.

• Geomechanics and Engineering
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• 제17권2호
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• pp.181-194
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• 2019

Due to the seepage of groundwater, the resisting force of slopes decreases and the sliding force increases, resulting in significantly reduced slope stability. The instability of most natural slopes is closely related to the influence of groundwater. Therefore, it is important to study slope stability under groundwater seepage conditions. Thus, using a simplified seepage model of groundwater combined with the analysis of stresses on the slip surface, the limit equilibrium (LE) analytical solutions for two- and three-dimensional slope stability under groundwater seepage are deduced in this work. Meanwhile, the general nonlinear Mohr-Coulomb (M-C) strength criterion is adopted to describe the shear failure of a slope. By comparing the results with the traditional LE methods on slope examples, the feasibility of the proposed method is verified. In contrast to traditional LE methods, the proposed method is more suitable for analyzing slope stability under complex conditions. In addition, to facilitate the optimization of drainage design in the slope, stability charts are drawn for slopes with different groundwater tables. Furthermore, the study concluded that: (1) when the hydraulic gradient of groundwater is small, the effect on slope stability is also small for a change in the groundwater table; and (2) compared with a slope without a groundwater table, a slope with a groundwater table has a larger failure range under groundwater seepage.

• 한국지반공학회논문집
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• 제38권8호
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• pp.29-37
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• 2022

연직배수재로 개량된 지반의 배수거동을 해석하기 위해서는 3차원 해석이 필요한데, Macro-element법을 이용하면 2차원 평면변형 조건으로 연직배수재의 3차원 배수효과를 고려한 효과적인 해석이 가능하다. 본 연구에서는 지반개량에서 적용되는 진공압밀공법에 Macro-element법을 적용하여 새로운 유한요소해석 프로그램을 개발하였다. 기존의 Macro-element법은 배수재의 과잉간극수압을 0으로 하여 연직배수량을 산정하였으나, 본 연구에서 개발된 프로그램은 부(-)의 과잉간극수압을 실제 진공압밀 조건과 동일하게 고려할 수 있도록 개선하였다. 프로그램의 성능 검증을 위해 진공압밀공법 적용 현장의 계측치와 비교한 결과, 프로그램으로 예측한 결과와 현장 계측데이터는 동일한 침하거동을 나타내었다.

• Environmental Engineering Research
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• 제18권3호
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• pp.117-121
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• 2013

For underpasses in Yeongjong Sky City business district, the guided drainage system, as a buoyancy prevention system has been designed, and is under construction. This paper investigates the safety of the guided drainage system for underpass structures being constructed in Yeongjong Sky City business district. This paper also calculates the amount of outflowing groundwater generated by the guided drainage system, and proposes alternative usages of the water. In order to investigate safety and field applicability of the guided drainage system for underpasses, characteristics of the surface flow for the area of interest have been analyzed, and the flow change of groundwater following the underpass structure construction has been evaluated using the 3-dimensional groundwater program MODFLOW. The influence of ground water on safety of the underpass structures has been calculated by FLAC2D analysis. For alternative usages for the outflowing groundwater generated by the guided drainage system, utilization methods of the outflowing groundwater in national and international resources have been researched. The amount of an outflowing groundwater to be generated in the area of interest has been analyzed, and efficient potential usages of this groundwater have been researched. When guided drainage technique is applied, the change in flow of groundwater must be evaluated and considered as safety factor relating to the buoyancy of the structure. As a result, safety factor demonstrated more than 1.2, meaning that the underpass structure is safe. The amount of subsoil drain generated by the guided drainage system was also analyzed. The quality and amount of water satisfied the standards and volume requirements, so as to make it applicable for a number of uses, such as X, Y, and Z, and should prove to be a valuable resource as the circumstances of the neighboring area change over time. These resources can be used as basic data for future urban water circulation studies, as well as generating research of alternative water usages.