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퇴적물 내의 하이드레이트 생성/해리 메커니즘과 탐사 및 개발생산에의 적용
이주용(Lee, J.Y.) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.05
The thermal signature of nucleation process is characterized by the induction time, the degree of supercooling, and the equilibrium temperature depression. The initiation of nucleation presents stochastic characteristics. The factors that affect nucleation are mechanical impact, ionic concentration, mineral surface characters, and pore size. Hydrate-bearing sediments behave mechanically like other cemented sediments. The data set has important implications for the calibration and interpretation of geophysical measurements and downhole logs collected in gas hydrate provinces, providing particular insight for the interpretation of P- and S-wave data and resistivity logs. In addition, laboratory formation history and ensuing pore-scale spatial distribution likely have a more pronounced effect on the macroscale mechanical properties of hydrate-bearing sediments
이주용(Lee, J.Y.),이재형(Lee, J.H.),이대성(Lee, D.S.),이원석(Lee, W.S.),김세준(Kim, S.J.),허대기(Huh, D.G.),김현태(Kim, H.T.) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.10
Electrical resistivity in hydrate-bearing sediments is sensitive to porosity, gas hydrate saturation, gas content, pore fluid composition, and temperature, so electrical measurements such as well logs and electromagnetic surveys have been used to explore gas hydrate-bearing formation. The high pressure tomography cell is designed considering the effect of electrode configuration and electrical shielding on tomography measurements and the safety. The evolution of electrical conductivity during CO₂ hydrate formation and dissociation reflects the combined effects of concurrent changes that include ionization of dissolved CO₂, temperature-dependent ionic mobility, changes in the degree of saturation, ion exclusion, surface conduction, and porosity changes. Measurements during hydrate formation and dissociation require careful analysis to properly interpret signatures, in particular when out-of plane conductivity anomalies prevail.
하이드레이트 함유 퇴적물의 역학적 성질 및 지구물리 특성
이주용(Lee, J.Y.),Francisca, F.,Santamarina, J.C.,Ruppel, C. 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
Using an oedometer cell instrumented to measure the evolution of electromagnetic properties, small strain stiffness, and temperature, we conducted consolidation tests on four types of sediments. The tested specimens include sediments with different gas hydrate saturation at four stages of loading. The test results show that the electromagnetic and mechanical properties of hydrate-bearing marine sediments are governed by the vertical effective stress, stress history, porosity, hydrate saturation, fabric, ionic concentration of the pore fluid, and temperature. The results also show that permittivity and electrical conductivity data can be combined to estimate hydrate volume fraction in laboratory sediments, methodology that might eventually be extended for estimation of hydrate concentrations in field settings.
태풍 Ewiniar(2006)에 의한 해운대 해수욕장의 해안선 변형분석 및 토사이동모형의 평가
이정렬(J.L.Lee),임흥수(H.S.Lim),이주용(J.Y.Lee) 한국해양환경·에너지학회 2006 한국해양환경·에너지학회 학술대회논문집 Vol.2006 No.-
태풍의 영향으로 해운대 해수욕장의 해안선이 어떻게 반응하는 지를 살펴보았다. 태풍 에위니아(Ewiniar)와 같이 서측 해안으로 상륙한 태풍에 대하여 35시간 후에 해운대 해수욕장은 전체 해안선에 걸쳐 4m 내외의 침식이 발생하였고 약 하루 후인 58시간 후에는 주로 남해 서측 해안에서 퇴적 현상이 관측되었다. 파랑 운동에 대하여 주기 평균을 취하여 구한 해빈류를 이용하는 전형적인 토사 이동 모형의 결과와 파랑 운동 하에서 토사의 실시간 이동을 직접 구현하는 모형의 결과를 해안선 관측 자료와 비교한 결과 후자의 모형이 더 근접한 결과를 낳고 있다. The shoreline changes of Haeundae Beach due to the passage of Typhoon are investigated. For Typhoon Ewiniar to make a landfall at the western shore of Namhae coast, the whole shore was eroded more or less than 4m at 35 hrs after its landfall and the deposition was mainly occurred along the western beach after about 1 more day (at 58 hrs after landfall). In the present study, two types of sediment transport model are compared; the conventional wave-averaged sediment transport model and the phase-resolving sediement transport model. The latter shows better agreement when compared with shoreline measurements.
이슬기(S.G. Lee),이승수(S. Lee),이주용(J.Y. Lee),엄정아(J.A. Um),이원호(W.H. Yi) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.4
This paper presents the computational analysis of debris flow using multi-phase modeling and resulting impact force on the structure. The mixture of soil and water was modeled as slurry phase for various water content controlled by volume concentration of each material. Unsteady flow was solved for incompressible fluid in 3D domain and volume of fluid (VOF) method was introduced to trace the boundary between the slurry and the ambient air. Due to the shear thinning characteristics of slurry, nonlinear viscosity model was implemented. In order to verify the present method, the numerical computations were carried out for the experimental setup with the sloped channel employed in a previous study. As expected and shown in the previous experimental study, the greater impact force on the measuring plate was obtained for the larger angle of slope. In addition, the maximum impact force occurred much faster for the slurry with the higher water content. The comparison between the experimental results and the present computation shows a good agreement. It was also found that the critical water content at which the debris starts to flow was 35% at an inclination of 50° and 40% to 40°. As the result, it is expected that present method can be used to calculate the impact force of the debris flows on the structures, and can further be used for damage prediction and reduction.