• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.6 s.46
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• pp.21-30
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• 2005

In this study, a seismic design methodology for friction dampers based on the story shear force distribution of an elastic building structure is proposed. First, using two normalization methods for the slip-load of a friction damper, numerical analyses of various single-degree-of-freedom systems are peformed. From those analyses, the effect of the slip-load and the brace stiffness was investigated and the optimal silliness ratio of the brace versus original structure was found. Second, from the numerical analysis for five multi-story building structures with different natural frequency and the number of story, reasonable decision method for the total number of installation floor, location of installation and distribution of the slip-loads are drawn. In addition, an empirical equation on the optimal number of installation floor is proposed. Finally, the superiority of the proposed method compared to the existing design method is verified from the numerical analysis using real earthquake data.

• Journal of Korean Society on Water Environment
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• v.32 no.6
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• pp.589-599
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• 2016

Implemented since 2004, TPLC (Total Pollution Load Control) is the most powerful water-quality protection program. Recently, uncertainty of prediction using steady state model increased due to changing water environments, and necessity of a dynamic state model, especially the watershed model, gained importance. For application of watershed model on TPLC, it needs to be feasible to adjust the relationship (mass-balance) between discharged loads estimated by technical guidance, and arrived loads based on observed data at the watershed outlet. However, at HSPF, simulation is performed as a semi-distributed model (lumped model) in a sub-basin. Therefore, if the estimated discharged loads from individual pollution source is directly entered as the point source data into the RCHRES module (without delivery ratio), the pollutant load is not reduced properly until it reaches the outlet of the sub-basin. The hypothetic RCHRES generated using the HSPF BMP Reach Toolkit was applied to solve this problem (although this is not the original application of Reach Toolkit). It was observed that the impact of discharged load according to spatial distribution of pollution sources in a sub-basin, could be expressed by multi-segmentation of the hypothetical RCHRES. Thus, the discharged pollutant load could be adjusted easily by modification of the infiltration rate or characteristics of flow control devices.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.359-366
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• 2008

The load distribution and deformation of pile subjected to axial loads are evaluated by a load-transfer method. The emphasis is on quantifying the effect of coupled soil resistance that is closely related to the ratio of pile diameter to soil modulus $(D/E_s)$ and the ratio of total shaft resistance against total applied load $(R_s/Q)$, in rock-socketed drilled shafts using the coupled load-transfer method. The proposed analytical method that takes into account the soil coupling effect was developed using a modified Mindlin's point load solution. Through comparisons with field case studies, it was found that the proposed method in the present study estimated reasonable load transfer behavior of pile and coupling effects due to the transfer of shaft shear loading, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.47-54
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• 2006

H-pile can be more easily driven than pipe pile by pile driver and shows high skin friction and plugging effect. This experimental study was devoted to investigate skin friction of H group piles in granite soil under laboratory test. Pile arrangements $(1{\times}2,\;1{\times}3,\;2{\times}2,\;2{\times}3,\;3{\times}3)$, pile space (2D,4D,6D), and soil density $(D_r=40%,\;80%)$ were tested. The main results obtained from the model tests can be summarized as follows. Distribution ratio of skin friction for total load decreased by $48{\sim}39%$ (dense soil), $32{sim}27%$ (loose soil) as piles space ratio increases in case of $3{\times}3$ group piles. And the distribution ratio of skin friction by pile settlements under loose soil decreased by about $58{\sim}33.2%$ in $2{\times}2$ group piles and about $65{\sim}38%$ in $3{\times}3$ group piles respectively.

• Structural Engineering and Mechanics
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• v.63 no.4
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• pp.509-519
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• 2017

Wind field in mountainous regions demonstrates unique distribution characteristic as compared with the wind field of the flat area, wind load and wind effect are the key considerations in structural design of television towers situated in mountainous regions. The television tower to be constructed is located at the top of Xiushan Mountain in Nanjing, China. In order to investigate the impact of terrain factors of hilltops on wind loads, firstly a wind tunnel test was performed for the mountainous area within 800m from the television tower. Then the tower basal forces such as bending moments and shear strength were obtained based on high frequency force balance (HFFB) test. Based on the experiments, the improved method for determining the load combinations was applied to extract the response distribution patterns of foundation internal force and peak acceleration of the tower top, then the equivalent static wind loads were computed under different wind angles, load conditions and equivalent goals. The impact of terrain factors, damping ratio and equivalent goals on the wind load distribution of a television tower was discussed. Finally the equivalent static wind loads of the television tower under the 5 most adverse wind angles and 5 most adverse load conditions were computed. The experimental method, computations and research findings provide important references for the anti-wind design of high-rise structure built on hilltops.

• Coupled systems mechanics
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• v.7 no.5
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• pp.525-554
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• 2018

The paper deals with the study of the dynamics of the oscillating moving ring load acting in the interior of the hollow circular cylinder surrounded by an elastic medium. The axisymmetric loading case is considered and the study is made by employing the exact equations and relations of linear elastodynamics. The focus is on the influence of the oscillation of the moving load and the problem parameters such as the cylinder's thickness/radius ratio on the critical velocities. At the same time, the dependence between the interface stresses and load moving velocity under various frequencies of this load, as well as the frequency response of the mentioned stresses under various load velocity are investigated. In particular, it is established that oscillation of the moving load can cause the values of the critical velocity to decrease significantly and at the same time the oscillation of the moving load can lead to parametric resonance. It is also established that the critical velocity decreases with decreasing of the cylinder's thickness/radiusratio.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.364-373
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• 2001

This paper describes the variation of lubricant's temperature effects on elastohydrodynamic lubrication. The Newton-Raphson technique was used to solve the simultaneous system of Reynolds and elasticity equations. To show effects of lubricant's temperature, average temperature across the oil film was calculated using the energy equation. Pressure distribution, film shape, and temperature distribution were obtained for fully flooded conjunctions, and various dimensionless speed parameters while load and material parameters were held constant. Minimum film thickness were obtained for various material properties while load and velocity were held constant. It is drawn that the thermal effects have a strong influence on a minimum film thickness under high rolling velocity and slip ratio.

• Structural Engineering and Mechanics
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• v.20 no.4
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• pp.435-450
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• 2005

Here, the dynamic instability characteristics of aero-thermo-mechanically stressed functionally graded plates are investigated using finite element procedure. Temperature field is assumed to be a uniform distribution over the plate surface and varied in thickness direction only. Material properties are assumed to be temperature dependent and graded in the thickness direction according to simple power law distribution. For the numerical illustrations, silicon nitride/stainless steel is considered as functionally graded material. The aerodynamic pressure is evaluated based on first-order high Mach number approximation to the linear potential flow theory. The boundaries of the instability region are obtained using the principle of Bolotin's method and are conveniently represented in the non-dimensional excitation frequency-load amplitude plane. The variation dynamic instability width is highlighted considering various parameters such as gradient index, temperature, aerodynamic and mechanical loads, thickness and aspect ratios, and boundary condition.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1039-1046
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• 2022

After the COVID-19 pandemic, the spread of the untact culture and the Fourth Industrial Revolution, which generates various types of data, generated so much data that it was not compared to before. This led to higher data throughput, revealing little by little the limitations of the existing network system centered on vendors and hardware. Recently, SDN technology centered on users and software that can overcome these limitations is attracting attention. In addition, SDN-based load balancing techniques are expected to increase efficiency in the load balancing area of the server cluster in the data center, which generates and processes vast and diverse data. Unlike existing SDN load distribution studies, this paper proposes a load distribution technique in which a controller checks the state of a server according to the occurrence of an event rather than periodic confirmation through a monitoring technique and allocates a user's request by weighting it according to a load ratio. As a result of the desired experiment, the proposed technique showed a better equal load balancing effect than the comparison technique, so it is expected to be more effective in a server cluster in a large and packet-flowing data center.

• Structural Engineering and Mechanics
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• v.53 no.3
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• pp.497-517
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• 2015

In this study, nonlocal nonlinear buckling analysis of embedded polymeric temperature-dependent microplates resting on an elastic matrix as orthotropic temperature-dependent elastomeric medium is investigated. The microplate is reinforced by single-walled carbon nanotubes (SWCNTs) in which the equivalent material properties nanocomposite are estimated based on the rule of mixture. For the carbon-nanotube reinforced composite (CNTRC) plate, both cases of uniform distribution (UD) and functionally graded (FG) distribution patterns of SWCNT reinforcements are considered. The small size effects of microplate are considered based on Eringen's nonlocal theory. Based on orthotropic Mindlin plate theory along with von K$\acute{a}$rm$\acute{a}$n geometric nonlinearity and Hamilton's principle, the governing equations are derived. Generalized differential quadrature method (GDQM) is applied for obtaining the buckling load of system. The effects of different parameters such as nonlocal parameters, volume fractions of SWCNTs, distribution type of SWCNTs in polymer, elastomeric medium, aspect ratio, boundary condition, orientation of foundation orthtotropy direction and temperature are considered on the nonlinear buckling of the microplate. Results indicate that CNT distribution close to top and bottom are more efficient than those distributed nearby the mid-plane for increasing the buckling load.