• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.2
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• pp.155-169
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• 2007

A transport container for a 500 kCi tritium storage vessel was developed, which could be used for the transport of metal tritide from Wolsong TRF facility to a disposal site. The structural, thermal, shielding, and confinement analyses were performed for the container in a view of Type B. As a result of structural analysis, the developed container sustained its integrity under normal and accidental conditions. The maximum temperature increase of the inner storage vessel by radiation was evaluated at $134.8^{\circ}C at room temperature. In $800^{\circ}C$ fire test, The thermal barrier of container sustained the inner vessel at $405^{\circ}C after 30 min, which temperature was allowable for the container integrity since maximum design temperature of inner vessel was $550^{\circ}C. In the evaluation of the shielding, the activity of radiation was nearly zero on the outer surface of inner vessel. Consequently the transport container for a 500 kCi tritium was evaluated to pass all the safety tests including accidental condition, so it was concluded that the designed transport container is proper to be used.

• Journal of Korea Water Resources Association
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• v.52 no.10
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• pp.697-706
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• 2019

A multiphase flow modeling approach equipped with a hybrid turbulence modeling method is applied to compute the gravity currents in a rectangular channel. The present multiphase solver considers the dense fluid, the less-dense ambient fluid and the air above free surface as three phases with separate flow equations for each phase. The turbulent effect is simulated by the IDDES (improved delayed detach eddy simulation), a hybrid RANS/LES, approach which resolves the turbulent flow away from the wall in the LES mode and models the near wall flow in RANS mode on moderately fine computational meshes. The numerical results show that the present model can successfully reproduce the gravity currents in terms of the propagation speed of the current heads and the emergence of large-scale Kelvin-Helmholtz type interfacial billows and their three dimensional break down into smaller turbulent structures, even on the relatively coarse mesh for wall-modeled RANS computation with low-Reynolds number turbulence model. The present solutions reveal that the modeling approach can capture the large-scale three dimensional behaviors of gravity current head accompanied by the lobe-and-cleft instability at affordable computational resources, which is comparable to the LES results obtained on much fine meshes. It demonstrates that the multiphase modeling method using the hybrid turbulence model can be a promising engineering solver for predicting the physical behaviors of gravity currents in natural environmental configurations.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.121-131
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• 2008

In constructing a slurry trench cutoff wall, bentonite-water slurry is used to secure the stability of sidewalls during excavation before the wall is completed by backfilling. Unexpectedly, a thin but relatively impermeable layer called filter cake can be formed on the excavation surface, which significantly influences the result of slug test analysis in the cutoff wall if not considered. This study is to examine the effect of filter cake on evaluating hydraulic conductivity of the vertical cutoff wall through slug test analysis with the aid of the verified numerical program Slug_3D. The no-flux boundary conditions were adopted in Slug_3D to simulate the filter cake on the interface between the wall and the natural soil. A new set of type curves were built for applying the type curve method. New modification factors were obtained for using the modified line-fitting method. With consideration of filter cake, the type curve method and the modified line-fitting method were adopted to reanalyze the case study taken from EMCON (1995). The previous results achieved by Choi and Daniel (2006) without consideration of filter cake were compared with the present results obtained in this paper. The comparison emphasizes the necessity of considering filter cake when analyzing slug test results in vertical cutoff walls.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1A
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• pp.49-53
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• 2012

Coastal structures, constructed for preventing coastal slope erosion, often causes the scour on the boundary between the coastal structure and the sea-bed, which might lead to collapse of coastal structures. To prevent the collapse, the usual upright block type coastal structures can be modified to other forms or systems of coastal structures. To validate the performance of the proposed systems, it is necessary to conduct high cost hydraulic experiments. If numerical modeling can be performed prior to the hydraulic experiments and the performance of the proposed systems is analyzed numerically in advance, the expenses can be reduced significantly by optimizing the number of cases for conducting the experiments. In this study, a fluid-structure interaction analysis procedure is proposed for modeling the hydraulic experiments of costal structures using the finite element package, LS-DYNA. As can be found in the usual hydraulic experiments, fluid velocities of potential scour locations are monitored and analyzed in detail for four types of coastal structures, block, step, trapezoid and rubble mound.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.4
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• pp.273-280
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• 2012

The numerical simulation using the Lattice Boltzmann Method in the field of computational fluid dynamics becomes wider in the engineering applications because of its simplicity of update rules compared to the conventional Navier-Stokes solvers. Here, a two-dimensional D2Q9 LB model is numerically tested with a few new computational treatment on the free surface. The single relaxation time is applied under the gravitational field where applied only in the higher density fluid because of its big density difference. At the free surface, the reconstruction techniques in combination with boundary conditions is adopted in order to get some distribution function coming into the fluid site from the air one, and surface tension, early stable test for the gravitional field is considered in it. With the implementation of the gravitational profile, conserving the overall mass and grid dependency are observed during the calculations and freesurface advance track is well captured with an experiment.

• 한국벤처창업학회:학술대회논문집
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• 2017.04a
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• pp.62-62
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• 2017

최근 인공지능 시대 및 제 4차 산업 혁명 시대의 도래로 제품 간, 제품과 서비스 간, 서비스 간 산업이 다양한 형태로 진화 중이며, 이종기술 산업 간의 융 복합화로 새로운 제3의 신산업이 등장하고 있다. 또한 소위 말하는 O2O(Online to Offline)는 이미 운송, 금융(핀테크), 자동차(카테크), 숙박, 음식, 의료(헬스케어테크) 등 많은 산업 분야에 진출, 기존 전통 산업과 충돌, 인허가에 어려움을 겪고 있으며 이러한 O2O는 IOT(사물인터넷)로 급속도로 가속화 되고 있다. 이렇듯 4차 산업 혁명에 따른 신산업의 탄생은 산업의 경계를 붕괴하고 있음에도 산업별로 구분된 제도, 규제, 지원정책 등은 여전히 신산업 창업의 장애가 되고 있다. 이에, 본 연구에서는 국내 벤처특별법, 창업지원법, 1인 창조기업법 내 투자 지원 업종과 미국을 비롯한 해외 창업 관련법 내 창업 지원 제한 업종과의 비교 분석, 몇 가지 중요한 시사점을 도출했다. 먼저, 우리나라가 선진국에 비해 지나치게 투자 제한 업종이 많음을 확인했다. 또한 선진국은 미풍양속을 해치는 업종, 투기적 사업 등 사회통념상 문제가 되는 사행성 업종을 제외하고는 대다수의 업종이 정책 지원 대상이다. 업종과 더불어 투자 행위로 투자 심사를 해 신산업 투자에 매우 탄력적으로 운영할 수 있게 설계되어 있다. 심지어 미국의 경우, 적극적 창업 투자를 위해 업종 및 투자 행위에 대한 심의를 중소기업청이 직접 수행한다. 특히, 우리나라의 중소기업창업투자회사제도는 미국의 중소기업투자회사(SBIC) 제도와 유사한 반면 투자 제한 업종 뿐 아니라 제도 운영 특히, 창업투자회사에 대한 관리 측면에서 매우 큰 차이가 있음을 보여주고 있다. 우리나라 중기청은 간접관리를 하는 반면, 미국은 중기청 내에서 직접 관리를 하고 있다. 따라서 본 연구에서는 우리나라 창업 벤처 투자 제한을 미국을 비롯한 기타 외국의 사례에서와 같이 사회통념상 불가피한 업종과 더불어 투자 행위로 정의하길 제안한다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.238.1-238.1
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• 2015

2차원 탄소나노재료인 그래핀은 본연의 우수한 물성으로 인하여 전자소자, 에너지 저장매체, 유연성 전도막 등 다양한 분야로의 응용가능성이 제기되었다. 그러나 실제적인 응용을 위해서는 그래핀의 구조적인 결함을 최소화하며, 특성을 자유로이 제어하거나 향상시키는 공정의 개발이 필요하다. 일반적으로 화학적 도핑은 그래핀의 전기적 특성을 제어하는 효율적인 방법으로 알려져 있다. 화학적 도핑의 방법으로는 그래핀을 특정 가스 분위기에서 고온 열처리하거나 활성종들이 존재하는 플라즈마에 노출시킴으로써, 그래핀을 구성하는 탄소원자를 이종원자로 치환하거나 표면에 흡착시켜 기능화 된 그래핀을 얻는 방법 등이 제시되었다. 특히 플라즈마를 이용한 도핑방법은 저온에서 단시간의 처리로 효율적인 도핑이 가능하고, 인가전력, 처리시간 등의 플라즈마 변수를 변경하여 도핑정도를 수월하게 제어할 수 있다는 장점을 가지고 있다. 그러나 플라즈마 내에 존재하는 극성을 띄는 다양한 활성종들로 인하여 그래핀에 구조적인 결함을 형성하여 오히려 특성이 저하될 수 있어 이를 고려한 플라즈마 공정조건의 설정이 필수적이다. 따라서 본 연구에서는 플라즈마에 노출된 그래핀의 Raman 특성을 고찰함으로써 화학적 도핑과 구조적인 결함의 경계를 확립하고 구조결함의 형성을 최소화한 효율적인 도핑조건을 도출하였다. 고품질 그래핀은 물리적 박리법을 이용하여 300 nm 두께의 실리콘 산화막이 존재하는 실리콘 웨이퍼 위에 제작하였으며, 평행 평판형 직류 플라즈마 장치를 이용하여 전극의 위치, 인가전력, 처리시간을 변수로 암모니아(NH3) 플라즈마를 방전하여 그래핀의 Raman 특성변화를 관찰하였다. 그래핀의 구조적 결함 및 도핑은 라만 스펙트럼의 D, G, D', 2D밴드의 강도비와 G밴드의 위치와 반치폭(Full width at half maximum; FWHM)의 변화를 통해 확인하였다. 그 결과, 인가전력과 처리시간이 증가함에 따라 그래핀의 도핑레벨이 증가되고, 이후에는 도핑효과가 없어지고 결함의 정도가 상승하는 천이구역이 존재하며, 이를 넘어서는 너무 높은 인가적력의 처리는 그래핀에 결함을 형성하여 구조적인 붕괴를 야기함을 확인하였다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.1
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• pp.87-92
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• 2005

This study was investigated to examine gelatinization properties of waxy black rice starches. X-ray diffraction patterns in raw starches showed traditional A type of cereals. The crystalline regions of both black rice and Shinsunchalbyeo starches disappeared when temperature increased to $65^{\circ}C$ where the crystalline regions of two starches changed to amorphous ones. Scanning Electron Microscope showed that granule type of Shinsunchalbyeo starch was more collapsed compared to that of black rice starch heated at 6$0^{\circ}C$. Gelatinization in both samples completed when samples were heated at 63$^{\circ}C$. The results by Differential Scanning Calorimetry (DSC) revealed that gelatinization patterns were similar in both samples. In Rapid Visco Analyzer examination, there was no difference in peak viscosity, breakdown, final viscosity and setback between Shinsunchalbyeo and waxy black rice starches.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.111-116
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• 2005

2-D and 3-D resistivity surveys were carried out at the Deok-In2 levee during the period of arid and rainy seasons to assess the waterproof effectiveness of sheet pile and grouting sections and detect the location of pipings. Inverted resistivity sections clearly indicated the boundaries of sheet pile and grouting sections and the locations of pipings observed at the ground surface. Besides, GPR survey was carried out to verify the rear cavity of culvert in levee which is thought to be the major cause of levee breakdown, But the quality of GPR data was very poor due to the steel reinforcements buried in the culvert. Because it is not easy to apply various geophysical surveys upon concrete structures, newly designed hydraulic response test was proposed to assess the continuity of rear cavity of culvert in this study.

• Tunnel and Underground Space
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• v.12 no.4
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• pp.312-320
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• 2002

It is well-known that when single rock fractures undergo shear displacement, they are influenced by the boundary conditions and fracture roughness. In this case, aperture geometry will change by means of dilation due to the shear displacement. As fractures become the flow paths, fluid flow through rock fractures is affected by the void geometry. In this study, therefore, the influence of roughness on shear behavior of fractures has been investigated, and the resulting hydraulic behavior has been analyzed. In order for this study, a statistical method has been used to generate rough fractures, and they have been adopted into new conceptual models fur fracture shearing and flow calculations. The main contributions of this study are as follows: firstly, fracture shear behavior becomes less brittle with decreasing fracture roughness and increasing normal stress. Then, the characteristics of aperture distribution becomes those of roughness of fractures indicating its hydraulic significance. Finally, it is observed that with decreasing fracture roughness the breakdown of channel flow occurs more slowly.