• Proceedings of the KSR Conference
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• 2010.06a
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• pp.650-655
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• 2010

The ground vibration which is induced by train leads defect and crack of neighborhood structure. Consequently, in order to reduce the train vibration, it is need to appropriate countermeasure. Wave-guide typed roadbed induce the train vibration to a channel wave forms using the difference of the track layer's stiffness. Therefore train vibration is restrictively attenuated along the longitudinal direction of the track. 5 kind of wave-guide typed roadbed structure is selected in this paper. A finite element, time history, linear spectrum, transfer function and damping ratio analysis are performed to evaluate the vibration reduction efficiency as the wave-guide roadbed.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.618-622
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• 2007

In the past decades, complain about ground vibration and noise induced by pile driving has been quickly increased. Because of that, auger The role of train has expanded as mass transportation according to the increase of train passenger. The train operation personnel are more emphasis on the safety of train operation due to the increase of train's role. The reason is that the train transports many people daily. So, if there is natural disaster, such as earthquake, flood, high temperature, and so on, it will become disaster. Therefore, this paper introduces and proposes wayside detection system, which can be helpful for the safety assurance of train operation.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.624-628
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• 2003

Lanthanum oxyfluoride can be synthesized by mechanochemical (MC) reaction between lanthanum oxide ($La_2O_3$) and polytetrafluoroethylene (PTFE, ($({CF_2CF_2}_n)$) in air using a planetary mill. MC reaction between the two materials induced from intensive grinding operation. The MC reaction is almost finished by 240min, and the products ground for 240min or more are composed of LaOF, amorphous $La(CO_3)F$ and amorphous carbon (C). Heating this MC reaction products at $600^{\circ}C$ enables us to eliminate amorphous C and decompose $La(CO_3)F$ into LaOF, so that pure LaOF material can be obtained as the final product. The average particle size of the final product (purified LaOF) is around few ten nanometers.

• Korean Journal of Pharmacognosy
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• v.7 no.2
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• pp.95-97
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• 1976

Saponin was distributed in all tissues of Phytolacca americana and P. esculenta. Phytolaccoside E was a major saponin, but the callus tissues induced from stems of P. americana contained phytolaccoside B as a major component. Saponin contents in leaves and stems were almost similar to those in roots. Two unknown compounds, $C_{32}H_{50}O_{4}$ (triterpenoid) and $C_{18}H_{22}O_{5}{\cdot}H_2O$ (polyphenol) were isolated from seeds of both plant.

• Journal of KSNVE
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• v.9 no.1
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• pp.25-32
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• 1999

Ground vibrations induced from road were investigated to get the basic data that can be used to prepare countermeasures for environmental vibration problems. Vibration levels were measured simultaneously at three points in double distances from road. These data were analyzed with the type of vehicles. roads, media to understand the magnitudes and characteristics of distance attenuation of road vibrations. Vibration levels recorded on tapes were analyzed to understand the characteristics of frequency of road vibration. The range which could be influenced by the road vibration was estimated to take into account the mean of$L_{max}$ and distance attenuation of vibration level 5 m from roadside.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.602-608
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• 2016

Because of the random characteristics of lightning, the Monte Carlo method is applied to estimate the flashover rate due to lightning, however, the simulations using previous methods are difficult to both beginner and expert in power corporations. Therefore, this paper proposes the new and easy method to simulate the flashover rate by connection of electromagnetic transients program (EMTP) and MATLAB. The magnitude of a lightning strike is based on a curve measured in the field, while the classification of direct and indirect lightning depends on the striking distance. In a Korean distribution system, the flashover rate induced by lightning is simulated using proposed method. Simulations of the footing resistance according to the existence of an overhead ground wire (OHGW) are performed and the simulation results are discussed. The simulation results are compared with findings obtained with the IEEE Flash 2.0 program.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.290-291
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• 2015

병행하는 가공송전선로에서 휴전된 선로에 유도되는 전압은 수백에서 수만 볼트에 이른다. 이 때문에 휴전된 선로의 작업을 위해 선로의 양단 발 변전소에서 접지개폐기를 통하여 선로 접지를 하는 것은 물론 잔류 유도전압 제거를 위해 선로작업구간 근처 양단 철탑에도 접지를 시공하고 선로작업을 시행한다. 선로작업 완료 후 가압 시 발 변전소의 접지개폐기 개폐상태는 근무자가 감시제어시스템을 이용하여 확인 가능하다. 개폐기간 인터록시스템으로 접지상태에서 선로가압은 불가하지만, 선로에 작업자가 설치해 놓은 접지선이나 접지설비 등은 발 변전소 운전자가 접지제거 상태를 작업자에게 인위적으로 확인한 후 가압하는 방법으로 인하여 인적 실수에 의한 접지 중 가압되는 선로고장이 종종 발생되고 있다. 이러한 고장을 방지하기 위한 선로 상 접지 모니터링 시스템의 필요성이 있다.

• Earthquakes and Structures
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• v.11 no.6
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• pp.967-982
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• 2016

Current codes design the buildings based on life safety criteria. In a performance-based design (PBD) approach, decisions are made based on demands, such as target displacement and performance of structure in use. This type of design prevents loss of life but does not limit damages or maintain functionality. As a newly developed method, resilience-based design (RBD) aims to maintain functionality of buildings and provide liveable conditions after strong ground movement. In this paper, the seismic performance of plain and strengthened RC frames (an eight-story and two low-rise) is evaluated. In order to evaluate earthquake performance of the frames, the performance points of the frames are calculated by the capacity spectrum method (CSM) of ATC-40. This method estimates earthquake-induced deformation of an inelastic system using a reduced response spectrum. Finally, the seismic performances of the frames are evaluated and the results are compared with a resilience-based design criterion.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.177-185
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• 2018

The subsidence mechanism of ground surface is a complex phenomenon when multiple seam coal mining operations are carried out. Particularly, the coal mining beneath karstic formations causes a very special form of subsidence. The subsidence causes elasto-plastic deformation of the karstic layers and the collapse of cavities leads to dolinization and/or sinkhole formation. In this study, a sinkhole with a depth of 90 m and a width of 25 m formed in Gelik district within the coal-basin of Zonguldak (NW, Turkey) induced by multiple seam coal mining operations in the past has been presented as a case-history together with two-dimensional numerical simulations and InSAR monitoring. The computational results proved that the sinkhole was formed as a result of severe yielding in the close vicinity of the faults in contact with karstic formation due to multiple seam longwall mining at different levels.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.159-168
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• 2018

In this study, a real-time grouting management system based on the clogging theory was established to manage injection procedure in real time. This system is capable of estimating hydraulic permeability with the passage of time as the grout permeates through the ground, and therefore, capable of estimating real time injection distance and flow rate. By adopting the Controlled Injection Pressure (CoIP) model, it was feasible to predict the grout permeation status with the elapse of time by consecutively updating the hydraulic gradient and flow rate estimated from a clogging-induced alteration of pore volume. Moreover, a method to estimate the volume of the fractured gap according to the reduction in injection pressure was proposed. The validity of the proposed system was successfully established by comparing the estimated values with the measured field data.