• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.305-313
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• 2010

HDPE smooth and textured GMs were cut into dumbbell shape and notched where depth of the notch produced a ligament thickness of 90% to 10% of the nominal thickness of the specimen at 10% interval. Yield stress and elongation were measured of those samples and plotted on Graph. Yield stress and elongation at yield point decreases gradually as the notch depth is increased. Both installations damaged and notched GMs were used to understand stress crack behavior. Intact sample were notched in such a manner that the depth of notch produced a ligament thickness of 80% of the nominal thickness of the specimen. Installation damaged samples were not notched. Stress Crack Resistance behavior was observed using NCTL Test at $50{\pm}1^{\circ}C$ at different yield stresses immerging with pH 4 and pH 12 buffer solutions. Significant difference was observed in both cases.

• Anatomy and Cell Biology
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• v.57 no.1
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• pp.61-69
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• 2024

Hypogonadism is associated with an increased risk of coronary artery disease. This study sought to describe the histomorphology of the left coronary arteries of the adult male rabbit following orchiectomy and subsequent testosterone administration. We included 20 adult male rabbits, divided into a baseline group (n=2), an interventional group subjected to castration only (n=6), an intervention group subjected to castration followed by testosterone injection (n=6), and a control group (n=6). Key variables under investigation were serum testosterone levels, the intima-media thickness of coronary arteries, smooth muscle cell density, and adventitial collagen fiber density. The mean coronary arteries' intimal medial thickness was significantly higher in the castrated group than in controls (0.488 mm and 0.388 mm, respectively), while the testosterone-injected group had a mean of 0.440 mm. Mean smooth muscle cell density was significantly lower in the castrated rabbits vs. controls (26.96% and 47.80%, respectively), this observation being reversed with testosterone injection (47.53%). Mean adventitial collagen fiber density was significantly higher in the castrated group than in controls (66.6% and 36.1%, respectively), with a marginal difference after testosterone injection (65.2%). This study demonstrates that castrationinduced hypogonadism causes morphological changes in the coronary arteries that are partly reversible using testosterone injections. These findings provide a morphological basis for understanding the role of testosterone in coronary arteries.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.134-141
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• 2000

The real area of contacts, average film thickness, mean real pressure, and mean hydrodynamic pressure are investigated numerically in this study, especially for the parallel thrust bearing. Model surface is generated numerically with given autocorrelation function and some surface profile parameters. Then the average Reynolds equation contained flow factors and contact factor is applied to predict the effects of surface roughness in mixed lubrication regimes. In this equation, flow factors are defined as correction terms to smooth out high frequency surface roughness and contact factor is introduced to relieve from obtaining the average film thickness. Therefore the computation time to obtain h can be reduced.

• Tribology and Lubricants
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• v.16 no.6
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• pp.455-460
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• 2000

The real area of contacts, average film thickness, mean real pressure, and mean hydrodynamic pressure are investigated numerically in this study, especially for the parallel thrust bearing. Model surface is generated numerically with given autocorrelation function and some surface profile parameters. Then the average Reynolds equation contained flow factors and contact factor is applied to predict the effects of surface roughness in mixed lubrication regimes. In this equation, flow factors are defined as correction terms to smooth out high frequency surface roughness and contact factor is introduced to relieve from obtaining the average film thickness. Therefore the computation time to obtain barh h can be reduced.

• Natural Product Sciences
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• v.26 no.1
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• pp.71-78
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• 2020

The plant Dendropanax morbifera Léveille is effective folk medicines for the treatment of several conditions, such as infectious diseases, skin diseases, and other illnesses. Although the inhibitory effects of D. morbifera on the proliferation and migration of vascular smooth muscle cells (VSMCs) have been shown in our previous study, its effects in vivo remain to be elucidated. In this study, we aimed to investigate the protective effects of the extracts from D. morbifera (EDM) on neointimal hyperplasia of rat carotid artery and explore the underlying mechanisms. We observed that the ratio of intima to media thickness (I/M) was significantly decreased in the EDM-treated groups by ~80% compared to that of the control. The expression of Ki-67 and proliferating cell nuclear antigen was decreased by ~70% in the EDM-treated groups compared to that of the control. In addition, matrix metalloproteinase (MMP)2 and MMP9 significantly reduced in the neointimal layer of the EDM-treated groups. Moreover, the decreased levels of contractile phenotypic markers of VSMCs, such as α-smooth muscle actin, myocardin, and smooth muscle-myosin heavy chain, were successfully restored by EDM treatment. Furthermore, the levels of synthetic phenotypic markers, cellular retinal binding protein 1 and connexin 43 were also restored to normal levels. These results suggest that EDM inhibits vascular neointimal hyperplasia induced by balloon injury in rats via phenotypic modulation of VSMCs. Therefore, EDM may be a potential drug candidate for the prevention of restenosis.

• Journal of the Korea Fashion and Costume Design Association
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• v.15 no.4
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• pp.143-155
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• 2013

This study examined the motif, weave structure, fabric density, and thread thickness of the patterned silks excavated from the Lady Lee's Tomb to trace the weave composition of the 18th Century in Korea. Different weave compositions were adopted depending on the weave structure. Two weave structures appeared in these patterned silks : simple gauze and satin damask. In the case of simple gauze Jergori, all the components, Gil(bodice), Somae(Sleeve) had similar fabric density and thread thickness. On the other hand, the satin damask Jergoris was composed of the components of different fabric density and thread thickness. According to the fabric density and thread thickness, the motif sharpness of damask Jergori was represented in three different ways : smooth and clear, rough and clear, and rough and vague. This revealed that Lady Lee selected not only pattern but also fabric density and thread thickness in the design of damask Jergori.

• Journal of Ocean Engineering and Technology
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• v.1 no.1
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• pp.127-137
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• 1987

The evaluation of the elastic-plastic fracture toughness $J_{1C}$ was performed on the center of weld metal(CWM), the heat affected zone (HAZ) and the base metal (BM) of API 5LB steel pipes welded by the high frequency electric resistance welding. The $J_{1C}$ was evaluated by the JSME R-Curve and JSME SZW methods using the smooth and side-grooved specimens. The results are as follows; (1) The $J_{1C}$ values by the SZW method are overestimated as compared with those by the R-curve method, because the micro-crack is formed as SZW increase with the deformation at SZ after initiation of the ductile crack. (2) The everage of $J_{1C}$ values by the the R-curve and the SZW methods in side-grooved specimens tended to decrease in comparison with smooth specimens 9.42% at CWM, 4.2% at HAZ, 23.2% at BM, respectively. (3) The boundary of the fatigue pre-crack, stretched zone, and dimple regions appeared more clearly in side-grooved specimens, for the slight change of SZW in the direction of the plate thickness, as compared with smooth specimens.

• Journal of the Korean Society of Visualization
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• v.12 no.3
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• pp.15-20
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• 2014

Direct numerical simulation (DNS) dataset of a turbulent boundary layer (TBL) with a step change from smooth to rough surface is analyzed to examine spatially developing flow characteristics. The roughness elements are periodically arranged two-dimensional (2-D) spanwise rods with a streamwise pitch of ${\lambda}=8k$ ($=12{\theta}_{in}$), and the roughness height is $k=15{\theta}_{in}$, where ${\theta}_{in}$ is the inlet momentum thickness. The step change is introduced $80{\theta}_{in}$ downstream from the inlet. For the first time, full images from the DNS data with the step change from the smooth to rough walls is present to get some idea of the geometry of turbulent coherent structures over rough wall, especially focusing on their existence and partial dynamics over the rough wall. The results show predominance of hairpin vortices over the rough wall and their spanwise scale growth mechanism by merging.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.445-448
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• 2006

The effects of surface roughness on a spatially-developing turbulent boundary layer (TBL) were investigated by performing direct numerical simulations of TBLs over rough and smooth walls. The Reynolds number based on the momentum thickness was varied in the range $Re_{\theta}=300{\sim}1400$. The roughness elements used were periodically arranged two-dimensional spanwise rods, and the roughness height was $k=1.5{\theta}_{in}$, which corresponds to $k/{\delta}=0.045{\sim}0.125$. To avoid generating a rough wall inflow, which is prohibitively difficult, a step change from smooth to rough was placed $80{\theta}_{in}$ downstream from the inlet. The spatially-developing characteristics of the rough-wall TBL were examined. Along the streamwise direction, the friction velocity approached a constant value and a self-preserving form of the turbulent stress was obtained. Introduction of the roughness elements affected the turbulent stress not only in the roughness sublayer but also in the outer layer. Despite the roughness-induced increase of the turbulent stress in the outer layer, the roughness had only a relatively small effect on the anisotropic Reynolds stress tensor in the outer layer. Inspection of the triple products of the velocity fluctuations revealed that introducing the roughness elements onto the smooth wall had a marked effect on vertical turbulent transport across the whole TBL. By contrast, good surface similarity in the outer layer was obtained for the third-order moments of the velocity fluctuations.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.3
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• pp.173-182
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• 2002

We investigated the effects of operating variables, such as electrical. reactor and gas parameters on toluene removal and discharge property in the dielectric barrier discharge (DBD) process. The toluene removal was initiated with the energy transfer to the reactor by loading of voltages higher than the discharge onset value. The energy transfer and toluene removal increased with the applied voltage. Higher removal rate was observed with smooth surface electrode despite of lower energy transfer compared with the coarse electrode, because more uniform discharge can be obtained on smooth surface state. The decrease of dielectric material thickness enhanced the removal efficiency by increasing the discharge potential. The toluene removal efficiency decreased with the increase of the inlet concentration. The increase of gas retention time enhanced the removal efficiency by the increase of energy density. The oxygen and humidity contents seem to exert significant influences on the toluene removal by dominating the generation of electrons, ions, and radicals which are key factors in the removal mechanism.