• Journal of Ginseng Research
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• v.8 no.1
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• pp.8-14
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• 1984

A statistical analysis of saponin contents in various parts of raw red ginseng was studied. Saponin contents in main lateral and fee roots showed highly significant differences each other. Saponin contents in raw red ginseng had highly negative correlation with the root diameter (r= -0.926**). The estimation of saponin contents at mixing ratios of parts of root appeared to be possible.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.199-207
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• 2003

발전소 온배수와 같은 페열의 방류는 여타 방류와는 달리 방류량이 단위 호기당 20-50ton/s 가량으로 매우 크며, 따라서 그 영향을 받는 해역도 매우 크다는 점이 특징이다. 최근 국내에서 시도되고 있는 심층 온배수 방류는 주변수에 비해 밀도가 작은 제트나 플룸의 형성 후 급격한 부력상승과 밀도차에 의한 수평 부력 확장(lateral buoyant spread)이 준 지배적인 현상으로 하수장의 혼합에 비해 즘 더 복잡한 양상을 띄게 된다. (중략)

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1119-1126
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• 2021

Spacer grid with mixing vane had been widely used in nuclear reactor core. One of the main feather of spacer grid with mixing vane was that strong swirl flow was formed after the spacer grid. The swirl flow not only changed the bubble generation in the near wall field, but also affected the bubble behaviors in the center region of the subchannel. The interaction between bubble and the swirl flow was one of the basic phenomena for the two phase flow modeling in fuel assembly. To obatin better understanding on the bubble behaviors in swirl flow, full three dimension numerical simulations were conducted in the present paper. The swirl flow was assumed in the cylindral calculation domain. The bubble interface was captured by Volume Of Fluid (VOF) method. The properties of saturated water and steam at different pressure were applied in the simulation. The bubble trajectory, motion, shape and force were obtained based on the bubble parameters captured by VOF. The simulation cases in the present study included single bubble with different size, at different angular velocity conditions and at different pressure conditions. The results indicated that bubble migrated to the center in swirl flow with spiral motion type. The lateral migration was mainly related to shear stress magnitude and bubble size. The bubble moved toward the center with high velocity when the swirl magnitude was high. The largest bubble had the highest lateral migration velocity in the present study range. The effect of pressure was small when bubble size was the same. The prelimenery simulation result would be beneficial for better understanding complex two phase flow phenomena in fuel assembly with spacer grid.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.699-709
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• 2011

The uses of multi-dimensional hydrodynamic and water quality models are increasing to support a sustainable management of large dam reservoirs in Korea. Any modeling study requires selection of a proper spatial dimension of the model based on the characteristics of spatial variability of concerned simulation variables. For example, a laterally averaged two-dimensional (2D) model, which has been widely used in many large dam reservoirs in Korea, assumes that the lateral variations of hydrodynamic and water quality variables are negligible. However, there has been limited studies to give a justification of the assumption. The objectives of this study were to present the characteristics of spatial variations of water quality variables through intensive field monitoring in Daechung Reservoir, and provide information on a proper spatial dimension for different water quality parameters. The monitoring results showed that the lateral variations of water temperature are marginal, but those of DO, pH, and conductivity could be significant depending on the hydrological conditions and local algal biomass. In particular, the phytoplankton (Chl-a) and nutrient concentrations showed a significant lateral variation at R2 (Daejeongri) during low flow periods in 2008 possibly because of slow lateral mixing of tributary inflow from So-oak Stream and wind driven patchiness.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.4
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• pp.302-306
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• 1993

Assuming Gaussian distribution of the density difference between a turbulent jet river plume and its ambient saline water, a hydrodynamic solution for the lateral spreading of a river plume is developed. Two advantages can be expected from the assumption we made. Firstly, we need not consider mixing processes in the plume in dealing with this Problem. Secondly, by Putting pressure gradients which can be obtained from the density distribution, into the equation of motion, we can solve them easily. We compared the analytic solution with the fold data of the Nakdong river plume and found reasonably good correspondence.

• Journal of the Korean Geotechnical Society
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• v.33 no.10
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• pp.15-24
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• 2017

A self-supported temporary excavation method called Inclined Earth Retaining structure (IER) has been developed by improving an existing excavation method. The stability of the IER was proved with both model tests and field tests. Especially, the results of the model tests proved that the lateral displacement of a model retaining wall was significantly reduced in clay. In this study, the applicability of the IER installed in the soft clay ground is estimated by analyzing survey data collected in the construction field. The results of FE analysis show that the lateral displacement of the IER decreased by 70.9% of that of a single row, self-supported retaining wall using the same number of H-piles. Thus, using the IER method in the soft clay ground will increase the stability of the excavated ground with the effect restraining its lateral displacement. Furthermore, using Deep Cement Mixing (DCM) to the upper half embedded depth of front support is recommended as a subsidiary method of reducing the lateral displacement of IER in the soft clay ground based on FE analysis results.

• Nuclear Engineering and Technology
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• v.24 no.3
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• pp.263-273
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• 1992

The study on the velocity distribution and the pressure drop characteristic of the nuclear fuel assembly is of importance for the thermal hydraulic design and safety analysis. The purpose of this experimental study is to investigate the hydraulic mixing behind the different kinds of spacer grids in the now or rod bundles. In this study, the detailed hydraulic characteristics in subchannels of 5$\times$5 PWR(Pressurized Water Reactor) rod bundles were measured using one-component He-Ne LDV(Laser Doppler Velocimeter). Measurements of the axial velocity, turbulent intensities and pressure drops were peformed Lateral velocity, turbulent intensities and Reynolds shear stress were also measured by adjust-ing LDV alignment. Friction factors in rod bundles and loss coefficients for spacer grids were evaluated from the measured pressure drops. Hydraulic mixing performance for different kinds of spacer grids could be investigated by estimating the turbulent cross-flow mixing rates between neighboring subchannels.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1206-1211
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• 2010

Soil-cement, a hardened mixture of Portland cement, soil, and water that contain sufficient durability, has been widely utilised in Seoul urban construction sites to retain lateral earth pressures or reinforce grounds. However, little information has been reported about the strength characteristics of soil-cement constructed in Seoul urban area. In this study, we performed a number of unconfined test to the soil-cements mixed from soils sampled in 3 sites in Seoul urban area. Results indicate that unconfined strengths and optimum cement amounts of soil-cements are highly dependent on the proportion of coarse-grain particles of mixed soils. Furthermore, changes of unconfined strengths with curing time are diverse with respect to mixing conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.7
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• pp.512-519
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• 2009

Flow pulsation in the gap connecting with two parallel channels is investigated by RANS and URANS approaches. The two parallel channels are connected by a small channel called for a gap. The parallel channels are designed to have different cross section area with its ratio of 0.5. Computations are conducted using a CFX 11.0 code. The bulk Reynolds number is 60,000. Predicted results are compared with the previous experimental data. Mean velocity profile at the center of gap region are compared with experiments for its validation. Spectral analysis on the lateral velocity in the center of the gap was performed. Auto correlation for the axial-flow velocity pattern was presented. The unsteady structure of the flow pulsation was visualized in the region of the gap in the parallel channel.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2810-2815
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• 2008

Flow pulsation in the gap connecting with two parallel channels is investigated by RANS and URANS approaches. The two parallel channels are connected by a small channel called for a gap. The parallel channels are designed to have different cross section area with its ratio of 0.5. Computations are conducted using a CFX 11.0 code. The bulk Reynolds number is 60,000. Predicted results are compared with the previous experimental result. Mean velocity profile at the center of gap region are compared with experiments for its validation. Spectral analysis on the lateral velocity in the center of the gap is presented. Auto and cross correlation for the axial-flow velocity pattern are presented. The unsteady structure of the flow pulsation was visualized in the region of the gap in the parallel channel.