• Coupled systems mechanics
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• v.5 no.3
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• pp.235-254
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• 2016

A numerical model for fluid-structure interactions (abbr. FSI) is presented in the context of sloshing effects in movable, partially filled tanks to improve understanding of interactions between the fluid and the dynamics of a tank flexibly attached to a vehicle. The purpose of this model is to counteract the penalizing impact of the added mass effect on classical partitioned FSI coupling scheme: the proposed investigation is based on an added mass corrected version of the classical strongly coupled partitioned scheme presented in (Song et al. 2013). Results show that this corrected version systematically allows convergence to the coupled solution. In the rare cases where convergence is already obtained, the corrected version significantly reduces the number of iterations required. Finally, it is shown that the convergence limit imposed by added mass effect for the non-corrected coupling scheme, is directly dependent on the aspect ratio of the fluid domain and highly related to the precision order of the temporal discretization scheme.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.263-267
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• 1995

The usual methods for the temperature control of mass-concrete structures include the use of low-heat cement, pre-cooling, post-cooling, or sheet curing. In order to control the heat of hydration during the construction of mass-concrete structures, the combination of the above methods is commonly employed. For the construction of mass-concrete structures such as massive pier or anchor, it is necessary to control the curing temperature with pipe cooling. In this study, the method of analysis on the effect of pipe of was proposed to prevent the thermal cracking due to heat of hydration In addition the effect of covering the concrete surface with blanket insulation was investigated. The results of the present study may be useful for the prediction of curing temperature of mass-concrete structures and the reasonable construction management.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1115-1122
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• 2004

The paper discussed the effect of a tip mass on the stability of pipes on elastic foundations. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. With or without internal damping, the critical flow velocities of the pipes are investigated according to the variation of elastic foundation parameters and tip mass ratios. Also. the relationship between the eigenvalue branches and the corresponding flutter modes of the cantilevered pipes with a tip mass on the elastic foundations is fully investigated.

• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.325-330
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• 2019

Band convergence is known to be effective in improving thermoelectric performance by increasing the Seebeck coefficient without significantly reducing electrical conductivity. Decoupling of the Seebeck coefficient and electrical conductivity in converged bands is the key requirement. Yet, the degree of decoupling depends on the band parameters of the converging bands. Herein, we report theoretical transport properties of two valence bands as their energy difference changes from 0.25 eV to 0 eV. In order to demonstrate the effect of band parameters in transport, we first conducted calculations for the case where the two bands have the same parameters. Then, we conducted the same calculation by doubling the density-of-states effective mass of one valence band. Given that there are two bands, each band's effective mass was doubled one at a time while the other band's effective mass remained constant. We found that the decoupling was strongest when the bands participating in convergence had the same band parameters.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.5
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• pp.410-417
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• 2006

The present study predicted the effect of the flow rate of coolant on the absorption performance of a vertical falling film type absorber Heat and mass transfer peformances were numerically investigated. The exit temperatures of solution and coolant were decreased as the flow rate of the coolant was increased at the film Reynolds number of 100. The absorption mass flux was increased and then decreased as the distance from the inlet of the absorber was increased. The distance showing the maximum absorption mass flux was ranged from 0.3 to 0.5m. The heat flux and the absorption mass flux were increased and then slowly decreased as the flow rate of the coolant was increased. The maximum values were obtained at the flow rate of coolant of 2.0L/min.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.611-618
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• 2005

In this research, the effect of rock mass weathering on the side shear resistance of drilled shaft socketed into weathered rock was investigated. For that, a database of 23 cast-in-place concrete piles with diameters varying from 400mm to 1,500mm were socketed into weathered igneous/meta-igneous rock at four different sites. The static axial load tests were performed to examine the resistant behavior of the piles, and a comprehensive field/laboratory testing program at the field test site was also performed to describe the in situ rock mass conditions quantitatively. No correlation was found between the compressive strengths of intact rock and the side shear resistance of weathered/soft rock. The ground investigation data regarding the rock mass conditions (e.g. $E_m,\;E_{ur},\;_{plm}$, RMR, RQD, j) was found to be highly correlated with the side shear resistance, showing the coefficients of correlation greater than 0.7 in most cases. Additionally, the applicability of existing methods for the side shear resistance of piles in rock was verified by comparison with the field test data. The existing empirical relations between the compressive strength of intact rock and the side shear resistance(Horvath (1982), Rowe & Armitage(1987) etc.) appeared to overestimated the side shear resistance of all piles tested in this research unless additional consideration on the effect of rock mass weathering or fracturing was applied. The existing methods which consider the effect of rock mass condition were modified and/or extended for weathered rock mass where mass factor j is lower than 0.1, and RQD is below 50%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.7 s.238
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• pp.828-836
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• 2005

Impingement/effusion cooling technique is used for combustor liner or turbine parts cooling in gas turbine engine. In the impingement/effusion cooling system, the crossflow generated in the cooling channel induces an adverse effect on the cooling performance, which consequently affects the durability of the cooling system. In the present study, to reduce the adverse effect of the crossflow and improve the cooling performance, circular pin fins are installed in impingement/effusion cooling system and the heat transfer characteristics are investigated. The pin fins are installed between two perforated plates and the crossflow passes between these two plates. A blowing ratio is changed from 0.5 to 1.5 for the fixed jet Reynolds number of 10,000 and five circular pin fin arrangements are considered in this study. The local heat/mass transfer coefficients on the effusion plate are measured using a naphthalene sublimation method. The results show that local distributions of heat/mass transfer coefficient are changed due to the installation of pin fins. Due to the generation of vortex and wake by the pin fin, locally low heat/mass transfer regions are reduced. Moreover, the pin fin prevents the wall jet from being swept away, resulting in the increase of heat/mass transfer. When the pin fin is installed in front of the impinging let, the blockage effect on the crossflow enhances the heat/mass transfer. However, the pin fin installed just behind the impinging jet blocks up the wall jet, decreasing the heat/mass transfer. As the blowing ratio increases, the pin fins lead to the higher Sh value compared to the case without pin fins, inducing $16\%{\~}22\%$ enhancement of overall Sh value at high blowing ratio of M=1.5.

• Journal of Environmental Health Sciences
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• v.15 no.1
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• pp.97-120
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• 1989

This study was carried out to evaluate the effect of environmental health between the mass improvement and the partial improvement of privies in rural area. For this study, three villages were selected in Chun Sung County, Kangwon Province.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.36-42
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• 2016

Mass flow amplifier, which is an aerodynamic device, makes air flow increased by ejecting small amount of compressed air with $Coand{\breve{a}}$ effect. In this study, the flow characteristics of a mass flow amplifier were studied with various flow conditions and geometrical configurations. In order to improve the performance of mass flow amplifier, various values of clearance, diffuser angle and the aspect ratio of induced flow inlet to outlet were considered as design parameter. Furthermore, four different pressure conditions of compressed air were also considered. Numerical study was performed using the commercial CFD code, ANSYS CFX 14.5 with shear stress transport(SST) turbulent model. The results of pressure and velocity distributions were graphically depicted with different geometrical configurations and operating conditions.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.207-214
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• 2014

Mass and flow resistance in a square ribbed microchannel have been studied numerically using the Lattice Boltzmann Method. It has been build up on two dimensional nine velocity vectors model with single relaxation time method called the Lattice Bhatnagor-Gross-Krook model. To analyze the roughness effect on the flow resistance namely the friction factor and mass flow has been discussed at the slip flow regime, $0.01{\leq}Kn{\leq}0.10$, where Kn is the Knudsen number. The wall roughness is considered by square microelements with a relative roughness height up to maximum 10% of channel height. The velocity profiles in terms of streamlines near the riblets are demonstrated to be responsible for the roughness effect. It is found that the roughness effect leads to increase the flow resistance with roughness height but it is decreased significantly with increasing the space between two roughness elements as well as the Knudsen number. In addition, the mass flow decreased linearly with increasing both roughness height and gap but significantly changed at the slip flow regime.