• Tunnel and Underground Space
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• v.24 no.5
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• pp.344-353
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• 2014

In this study, the behavior of rock pillar in the diverging area of road tunnel was assessed by using a three dimensional numerical analysis. Based on parameters affecting the behavior of rock pillar, different safety factors according to pillar width, depth and rock conditions were evaluated. It turned out that as the pillar width increases, the change curve of safety factors in accordance with depth and rock conditions shows more of the nonlinear behavior. By the assessment of the minimum safety factor, a safety factor chart on the behavior of rock pillar in the diverging area of road tunnel was suggested.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.81-88
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• 2015

This study assessed the behavior of rock pillar in tunnel diverging area by using a three dimensional numerical analysis. Based on parameters affecting the behavior of rock pillar, this study evaluated different safety factors according to pillar width, depth and rock conditions. It turned out that as the rock pillar width increases, the change curve of safety factors in accordance with depth and rock conditions shows more of the nonlinear behavior. By the assessment of the minimum safety factor, a safety factor chart on the behavior of rock pillar in tunnel diverging area was suggested.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.41-47
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• 2005

This paper deals with a squeal noise in a brake system. It has been proved that the squeal noise is influenced by the angular misalignment of a disk, disk run-out, with the previously experimental study. In this study, a cause of the noise is examined by using FE analysis program(SAMCEF) and numerical analyses with a derived analytical equation of the disk based on the experimental results. The FE analyses and numerical results show that the squeal noise is due to the disk run-out as the experimental results and the frequency component of the noise equals to that of a disk's bending mode arising from the Hopf bifurcation.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.595-600
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• 2004

This paper deals with a cause analysis of a squeal noise in a brake system. It has been proved that the squeal noise is influenced by the angular misalignment of a disk, disk run-out, with the previously experimental study. In this study, a cause of the noise is examined by using FE analysis program(SAMCEF) and numerical analyses with a derived analytical equation of the disk based on the experimental results. The FE analyses and numerical results show that the squeal noise is due to the disk run-out as the experimental results and the frequency component of the noise equals to that of a disk's bending mode arising from the Hopf bifurcation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.495-500
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• 2003

The vibration of a flexible cantilever tube with nonlinear constraints when it is subjected to flow internally with fluids is examined by experiment and theoretical analysis. These kind of studies have often been performed that finds the existence of chaotic motion. In this paper, the important parameters of the system leading to such a chaotic motion such as Young's modulus and coefficient of viscoelasticity in tube material are discussed. The parameters are investigated by means of a system identification so that comparisons are made between numerical analysis using the parameters of a handbook and the experimental results. The chaotic region led by several period-doubling bifurcations beyond the Hopf bifurcation is also re-established with phase portraits and bifurcation diagram so that one can define optimal parameters for system design.

• Journal of the Korean Geosynthetics Society
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• v.15 no.4
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• pp.17-23
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• 2016

This study assessed the behavior of rock pillar in tunnel asymmetric diverging area by using a three dimensional numerical analysis. The stability of pillar is very important for the ensure the stability of the tunnel asymmetric diverging area. Based on parameters affecting the behavior of rock pillar, this study evaluated different safety factors according to pillar width, depth and rock conditions. It turned out that as the rock pillar width increases, the change curve of safety factors in accordance with depth and rock conditions shows more of the nonlinear behavior. By the assessment of the minimum safety factor, a safety factor chart on the behavior of rock pillar in tunnel asymmetric diverging area was suggested.

• TTA REPORT
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• v.5 no.2 s.18
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• pp.18-31
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• 1993

국제 전기통신 연합(ITU)에서는 각국의 전기통신 관련 자료를 모아 지역별로 전기통신에 관한 지표 자료집을 발간하였다. 이 자료집은 유럽, 구소련, 미주, 아랍, 아프리카, 아시아$\cdot$태평양 등 6개 지역으로 구분하여 각 지역에 해당된 국가별로 1981년부터 10년동안의 각국의 전기통신에 관련된 자세한 정보를 싣고 있다. 각각의 자료집에는 해당 지역의 ITU 회원국들의 지난 10년간 공중통신과 관련된 각종 정보들을 도표와 그래프를 이용하여 알기 쉽고 일목 요연하게 잘 설명해 주고 있다. 아시아와 아프리카에 관한 자료는 올 1/4분기 안에 발행될 예정에 있어 아직 자료를 입수하지 못하였으나 다른 4개 지역에 대한 ITU 발간 자료를 수집하여 전기통신 현황에 관한 통계의 참고자료로 삼고 있다. 이들 책자를 통해 나타난 바를 지역별로 간단히 요약해 보자

• Korean Security Journal
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• no.30
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• pp.139-169
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• 2012

The purpose of this study is to contribute to establishing the scientific policing policies through deriving the time series models that can forecast the occurrence of major crimes such as murder, robbery, burglary, rape, violence and identifying the occurrence of major crimes using the models. In order to achieve this purpose, there were performed the statistical methods such as Generation of Time Series Model(C) for identifying the forecasting models of time series, Generation of Time Series Model(C) and Sequential Chart of Time Series(N) for identifying the accuracy of the forecasting models of time series on the monthly incidence of major crimes from 2002 to 2010 using IBM PASW(SPSS) 19.0. The following is the result of the study. First, murder, robbery, rape, theft and violence crime's forecasting models of time series are Simple Season, Winters Multiplicative, ARIMA(0,1,1)(0,1,1), ARIMA(1,1,0 )(0,1,1) and Simple Season. Second, it is possible to forecast the short-term's occurrence of major crimes such as murder, robbery, burglary, rape, violence using the forecasting models of time series. Based on the result of this study, we have to suggest various forecasting models of time series continuously, and have to concern the long-term forecasting models of time series which is based on the quarterly, yearly incidence of major crimes.