• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.43-49
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• 2012

In the design of high speed railway bridges is important a impact factor as a tool of assessing the dynamic capacitys of bridges. However, the impact factor(or dynamic amplification factor, DAF) of high speed railway bridges may essentially be changeable because the dynamic response is affected by the long train length(380 m), number of axles and high speed velocity(300 km/h)(Korea Train eXpress: KTX). Therefore, on this study will be examined the dynamic capacity and stability of the typical PSC Box Girder of high speed railway bridge. At first, the static/dynamic analysis is performed considering the axle load line of KTX based upon existing references. Additionally, the KTX moving load is transformed into the dynamic time series load for conducting various parameter studies like axle length, analytical time increment, velocity of KTX. The time history analysis is repeatedly performed to get maximum dynamic responce by varying axle load length, analytical time increment, velocity of KTX. The study shows that dynamic analysis has resonable results with optimal axle load length(0.6 m) and time increment(0.01 sec.) and maximum DAF and dynamic resonance happens at 270 km/h velocity of KTX.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.5
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• pp.117-124
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• 2019

Nonstructural elements are installed according to the function of a building, and refer to the elements other than a structural system that resists external loads. Although the nonstructural elements had the largest part of seismic loss of buildings, seismic design of buildings mainly focuses on structural system and the seismic design of nonstructural elements are rarely conducted. In this study, the seismic design provisions of nonstructural elements presented in Uniform Building Code (UBC) and International Building Code (IBC) were investigated in order to analyze the seismic design considerations of nonstructural elements presented in Korean Building Code (KBC). The results showed that the equivalent static load applied to seismic design of nonstructural elements was revised to take into consideration a total of five items such as effective ground acceleration, vertical amplification factor, response amplification factor, response modification factor, importance factor.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.371-379
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• 1993

The wrinkling in the electromagnetic tube compression with a mandrel is remarkably smaller than that of the process without it. To analyze this phenomenon, the critical forming parameters such as the ratio of the clearance to the shell radius, the ratio of the thickness to the shell radius, and the ratio of the applied pressure to the standard pressure are introduced tp consider the effect of the mandrel, in addition to those of the thickness of shell and applied loads. The amplification ratio is also used to observe the magnitude of amplification. The results obtained by 2-D finite element method show that the initial imperfection embedded in the radius of cylindrical shell is the dominant factor to determine the final shape of the tube compression, and that the amplification ratio tends to have smaller values with the smaller clearance ratio and also with the larger thickness and pressure ratios.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.4
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• pp.295-302
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• 1993

The nature of the cavity region and dispersion around trianglular ridge was investigated using model. The artifical neutral boundary layer was simulated in water channel. Two dimensional trianglar ridges, having height of 1.2 cm and various width were placed normal to the flow. Mean velocity with many dimensionless parameters were measured and compared with wind tunnel results by other studies. Using vorticity generator and roughness, the neutral boundary layer was well represented by the water channel. concentration patterns resulting from dye source placed 0.2 cm height above were examined. Narrower the trianglar ridge width resulted in increased amplification factor and the larges amplification factor was observed near downward top of the ridge.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.421-428
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• 2005

In this paper, the performance of a toggle brace-MR damper system is evaluated for the control of the structure excited by earthquake load and the non-linearity of the toggle system is investigated. Considering that the control force of MR damper described by Bingham model is a function of velocity, velocity amplification factor by toggle brace system is calculated and the effect of toggle configuration on the amplification factor is also evaluated. Numerical results show that the control performance can be largely enhanced using toggle brace system especially for the case that the MR damper installed with conventional brace system such as Chevron and diagonal cannot provide enough control force under severe earthquake load.

• Structural Engineering and Mechanics
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• v.45 no.6
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• pp.821-835
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• 2013

The acceleration that the electrical equipment experiences on a structure can be several times the ground acceleration. Currently, substation support structures are being designed according to ASCE (Substation Structure Design Guide 2008), without any consideration about effects of these structures on dynamic behavior of mounted equipment. In this paper, a parametric study is implemented in order to improve seismic design of candlestick substation structures based on this design guide. To do this, dynamic amplification factor (DAF) of different candlestick support-equipment combinations is evaluated and compared to the target DAF presented in IEEE STD 693 (2006). Based on this procedure, a new criterion is developed to restrict maximum acceleration at support-equipment intersection.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.215-218
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• 2001

In conventional three-phase rectifiers, it was necessary to use a transformer to obtain low output voltage. In this paper, we propose a new three-phase rectifiers circuit that achieves low voltage by using a very simple circuit configuration that does not have a transformer and does not need any complex control. We also describe the operation principle of the proposed circuit, and derive a theoretical formula for its current waveform. On the basis of this formula it also explores the theoretical input/output current characteristics, theoretical current amplification factor, and theoretical output voltage characteristics of these theoretical values with experimentally obtained input/output current characteristics, current amplification factor, and output voltage characteristics, allowed us to confirm the soundness of our theoretical analyses.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.375.1-375.1
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• 2016

Polymerase chain reaction (PCR) has revolutionized genetics and become one of the most popular techniques in modern biological and medical sciences. It can be used not only as an in vitro DNA amplification method but also used in many bioassay applications. The PCR can be used to exponentially produce a large number of DNA copies from a small quantity of DNA molecules in a few hours. However, as unwanted DNA fragments are also often manufactured, the amplification efficiency of PCR is decreased. To overcome this limitation, several nanomaterials have been employed to increase the specificity of the PCR reaction. Recently, graphene has attracted a great interest for its excellent electron transfer, thermal and biocompatibility. Especially, gold nanoparticle-coated graphene oxide (GO/AuNPs) led to enhance electron and thermal transfer rate and low-charge transfer resistance. Therefore, we report the development of a demonstration for the PCR efficiency using a large-scale production of the GO and combination of gold nanoparticles. Because a thermal conductivity is an important factor for improving the PCR efficiency in different DNA polymerases and different size samples. When PCR use GO/AuNPs, the result of transmission electron microscopy and real-time quantitative PCR (qPCR) showed an enhanced PCR efficiency. We have demonstrated that GO/AuNPs would be simply outperformed for enhancing the specificity and efficiency of DNA amplification procedure.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.1
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• pp.40-45
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• 2007

The repeaterless system can be designed by applying EDFA technology in receiver, transmitter and optical cable in the case of connecting several hundred km from coast to coast, between continents or islands. Because of no repeater the repeaterless system do not need power system to feed laser diode in repeater for signal amplification and cooper tuber in submarine cable. So we can be configured more reliable and economical compared to repeater system. But lower loss optical fiber must be used to get enough signal amplitude without the amplification of repeater. This report consider long distance optical repeaterless system by reflecting the limitation factor of optical amplification.

• Earthquakes and Structures
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• v.4 no.5
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• pp.557-585
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• 2013

The recent huge earthquake ground motion records in Japan result in the reconsideration of seismic design forces for nuclear power stations from the view point of seismological research. In addition, the seismic design force should be defined also from the view point of structural engineering. In this paper it is shown that one of the occurrence mechanisms of such large acceleration in recent seismic records (recorded in or near massive structures and not free-field ground motions) is due to the interaction between a massive building and its surrounding soil which induces amplification of local mode in the surface soil. Furthermore on-site investigation after earthquakes in the nuclear power stations reveals some damages of soil around the building (cracks, settlement and sand boiling). The influence of plastic behavior of soil is investigated in the context of interaction between the structure and the surrounding soil. Moreover the amplification property of the surface soil is investigated from the seismic records of the Suruga-gulf earthquake in 2009 and the 2011 off the Pacific coast of Tohoku earthquake in 2011. Two methods are introduced for the analysis of the non-stationary process of ground motions. It is shown that the non-stationary Fourier spectra can detect the temporal change of frequency contents of ground motions and the displacement profile integrated from its acceleration profile is useful to evaluate the seismic behavior of the building and the surrounding soil.