• 한국지반신소재학회논문집
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• 제4권4호
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• pp.3-11
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• 2005

본 연구에서는 지오텍스타일 백으로 보강된 철도노반 강화효과를 확인하기 위하여 실대형실험 및 2차원 평면 수치해석을 수행하였다. 선정된 지오텍스타일 백 축조노반위에 모사열차하중을 고려한 정적하중을 재하하여 무보강 노반과의 비교를 통해 정량적인 보강효과 및 성능을 평가하였으며, 2차원 평면 수치해석은 실대형실험과 동일 조건하에서 범용 FEM 프로그램인 Pentagon 2D를 이용하여 수치해석을 수행하여 비교 분석하였다. 각각의 실대형실험 및 2차원 수치해석결과 지오텍스타일 백의 재료특성, 인장특성, 지오텍스타일 백간의 마찰특성등에 의해 하중분산효과 및 침하저감효과를 확인하였으며, 2차원 수치해석결과가 실대형 실험결과 보다 전반적으로 작게 나타남을 확인하였다.

• 한국철도학회논문집
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• 제19권2호
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• pp.213-223
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• 2016

도시에 밀집된 인구에 의하여 교통 혼잡이 빈번하게 일어나고 있으며 그에 따른 도시민의 불편이 증대 되었다. 이러한 교통 불편을 최소화 하는 방안으로 저심도 철도와 같은 다양한 교통시스템이 제안되고 있다. 본 논문에서는 경제적인 저심도 철도시스템 구축을 위하여 개발중인 트렌치쉴드의 설계와 더불어 소형 트렌치 쉴드 장비를 제작하여 트렌치 쉴드의 적용성에 대한 검토가 이루어졌다. 본 논문에서 도출한 트렌치 쉴드는 굴착부와 쉴드부, 추진부로 구성되어있다. 이렇게 검토 및 설계된 트렌치쉴드의 적용성을 검토하기 위하여 실내실험을 추진하였으며 이를 통하여 트렌치 쉴드를 통한 개착시공현장의 급속시공이 가능함을 확인하였다. 비록 실내실험이고 상대적으로 소규모의 실험이지만 트렌치 쉴드를 이용할 경우 3m/일의 시공속도 확보가 가능할 것으로 판단된다.

• Wind and Structures
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• 제31권4호
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• pp.287-298
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• 2020

This paper presents an experimental investigation on the surface pressures on the CAARC standard tall building model concerning the effects of freestream turbulence. Two groups of incidence turbulence are generated in the wind tunnel experiment. The first group has an approximately constant turbulence intensity of 10.3% but different turbulence integral scale varying from 0.141 m to 0.599 m or from 0.93 to 5.88 in terms of scale ratio (turbulence integral scale to building dimension). The second group presents similar turbulence integral scale but different turbulence intensity ranging from 7.2% to 13.5%. The experimental results show that the mean pressure coefficients on about half of the axial length of the side faces near the leading edge slightly decrease as the turbulence integral scale ratio that is larger than 4.25 increases, but respond markedly to the changes in turbulence intensity. The root-mean-square (RMS) and peak pressure coefficients depend on both turbulence integral scale and intensity. The RMS pressure coefficients increase with turbulence integral scale and intensity. As the turbulence integral scale increases from 0.141 m to 0.599 m, the mean peak pressure coefficient increases by 7%, 20% and 32% at most on the windward, side faces and leeward of the building model, respectively. As the turbulence intensity increases from 7.2% to 13.5%, the mean value of peak pressure coefficient increases by 47%, 69% and 23% at most on windward, side faces and leeward, respectively. The values of cross-correlations of fluctuating pressures increase as the turbulence integral scale increases, but decrease as turbulence intensity increases in most cases.

• 한국철도학회논문집
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• 제9권2호
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• pp.180-186
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• 2006

In this study, a large-scale laboratory model test, 2-D and 3-D numerical analyses were conducted to verify the reinforcement effect by utilizing geotextile bag on the railway roadbed. Static loading which simulated train load was applied on the geotextile bag-reinforced railway roadbed and also unreinforced railway roadbed, Computer program named Pentagon which is a part of FEM programs was used in the numerical analysis. Based on the results of laboratory test, 2-D and 3-D numerical analyses, the effect of load distribution and settlement reduction was found to be depending on the geotextile characteristics, tensile strength of geotextite, and interface friction angle between geotextile bags. In general, the result of 2-D and 3-D numerical analyses shows lower value than that of laboratory test. Also, the result of 3-D numerical analyses shows lower value than that of 2-D numerical analyses because of its stress transfer effect.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 3차
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• pp.55-60
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• 2010

Rockfill zones in CFRD consist typically of large granular materials, usually the maximum particle size up to several meters, which makes laboratory testing to determine the mechanical properties of rockfill difficult. Commonly, the design strength of the rockfills is obtained by scaling down the original rockfill materials and performing laboratory strength tests for the reduced size materials. The objective of the present study is to investigate the effect of particle size on the shear behavior and the strength for granular materials. A series of large-scale triaxial tests was conducted on large granular materials with the maximum particle size varying from 20 to 50mm. The test results showed that overall shear behaviors were similar between the samples with different particle sizes while there were slight differences in the magnitudes of the peak shear stress between the samples. In addition, a simulation of the granular material with the max. particle size of 20mm was performed using DEM code, $PFC^{2D}$, and compared with the test results. The deviatoric stress versus strain behaviors of experimental and numerical tests were found to be matched well up to the peak stress state.

• Korean Chemical Engineering Research
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• 제58권1호
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• pp.150-162
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• 2020

The proprietary post-combustion CO₂ solvent (KoSol) developed by the Korea Electric Power Research Institute (KEPRI) was applied at the Shanghai Shidongkou CO₂ Capture Pilot Plant (China Huaneng CERI, capacity: 120,000 ton CO₂/yr) of the China Huaneng Group (CHNG) for performance evaluation. The key results of the pilot test and data on the South Korean/Chinese electric power market were used to calculate the predicted cost of CO₂ avoided upon deployment of CO₂ capture technology in commercial-scale coal-fired power plants. Sensitivity analysis was performed for the key factors. It is estimated that, in the case of South Korea, the calculated cost of CO₂ avoided for an 960 MW ultra-supercritical (USC) coal-fired power plant is approximately 35~44 USD/tCO₂ (excluding CO₂ transportation and storage costs). Conversely, applying the same technology to a 1,000 MW USC coal-fired power plant in Shanghai, China, results in a slightly lower cost (32~42 USD/tCO₂). This study confirms the importance of international cooperation that takes into consideration the geographical locations and the performance of CO₂ capture technology for the involved countries in the process of advancing the economic efficiency of large-scale CCS technology aimed to reduce greenhouse gases

• Wind and Structures
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• 제6권2호
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• pp.91-106
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• 2003

The paper presents the results of 1:50 geometrical scale laboratory modeling of wind-induced point pressure on the roof of the Texas Tech University (TTU) test building. The nominal (prevalent at the TTU site) wind and two bounding (low and high turbulence) flows were simulated in a boundary-layer wind tunnel at Colorado State University. The results showed significant increase in the pressure peak and standard deviation with an increase in the flow turbulence. It was concluded that the roof mid-plane pressure sensitivity to the turbulence intensity was the cause of the previously reported field-laboratory mismatch of the fluctuating pressure, for wind normal and $30^{\circ}$-off normal to the building ridge. In addition, it was concluded that the cornering wind mismatch in the roof corner/edge regions could not be solely attributed to the wind-azimuth-independent discrepancy between the turbulence intensity of the approach field and laboratory flows.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1902-1912
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• 2024

This paper presents results from system-level modeling of a water-based reactor cavity cooling system using RELAP5-3D. The computational model is benchmarked with experimental data from a half-scale RCCS test facility at Argonne National Laboratory. The model prediction is first compared with a two-phase oscillatory baseline experimental case where mixed accuracy is obtained. The model shows reasonable prediction of mass flow rate, pressure, and temperature but significant overprediction of void fraction. The model prediction is then compared with a fault case where the inlet of the risers is gradually reduced using a throttling valve. As the valve is closed, the model is able to predict some major flow phenomena observed in the experiment such as the dampening of oscillations, the reintroduction of oscillations, as well as boiling, flashing, and geysering in the risers. However, the timeline of these events are not well captured by the model. The model is also used to investigate the evolution of flow regime in the chimney. This work highlights that the semi-empirical constitutive relations used in RELAP-3D could have a strong influence on the accuracy of the model in two-phase oscillatory flows.

• 한국산학기술학회논문지
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• 제12권8호
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• pp.3723-3728
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• 2011

이 연구에서는 암반과 그라우팅 사이의 마찰거동에 대하여 고찰하고자 실내실험과 중대형 실험을 수행하였다. 실내실험의 경우 암반에 대한 모사는 특별히 제작된 원통형 몰드를 통해 구현하였으며 모형토조실험의 경우, 인공암반을 토조에 조성한 후 압력식과 중력식 그라우팅에 따른 그라우트체의 인발거동을 측정하였다. 두 종류의 실험결과 모두 압력식 그라우팅이 암반과 그라우트체의 벽면 마찰거동에 큰 영향을 미치는 것으로 나타났다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.269-272
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• 2006

Numerical analysis of wind turbine scale effect was performed by using computational fluid dynamics. For the numerical analysis of wind turbine. Three dimensional Navier-Stokes solver with various turbulence models was tested and realizable k-e turbulence model was selected for the simulation of wind turbines. To validate the present method, performance of NREL (National Renewable Energy Laboratory) Phase VI wind turbine model was analyzed and compared with experiment and blind test data. Using the present method, numerical simulations for various size of wind tunnel model were carried out and characteristics were observed in detail. The power loss due to the interference between wind turbine and nacelle was also computed for relatively larger nacelle installation in wind tunnel test. The present results showed good correlations with experimental data and reasonable trends of scale effect of wind turbine.