• Proceedings of the KSEEG Conference
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• 2000.04b
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• pp.182-183
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• 2000

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.241-251
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• 2007

The observed spectra from Odaesan earthquake were fitted to a point-source spectral model to evaluate the source spectrum and spatial features of the modelling error. The source spectrum was calculated by removing from the observed spectra the path and site dependent responses (Yun, 2007) that were previously revealed through an inversion process applied to a large accumulated spectral dataset. The stress drop parameter of one-corner Brune's ${\omega}^2$ source model fitted to the estimated source spectrum was well predicted by the scaling relation between magnitude and stress drop developed by Yun et al. (2006). In particular, the estimated spectrum was quite comparable to the two-corner source model that was empirically developed for recent moderate earthquakes occurring around the Korean Peninsula, which indicates that Odaesan earthquake is one of typical moderate earthquakes representative of Korean Peninsula. Other features of the observed spectra from Odaesan earthquake were also evaluated based on the commonly treated random error between the observed data and the estimated point-source spectral model. Radiation pattern of the error according to azimuth angle was found to be similar to the theoretical estimate. It was also observed that the spatial distribution of the errors was correlated with the geological map and the $Q_0$ map which are indicatives of seismic boundaries.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1434-1439
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• 2012

Vehicle is a dynamic system combined with various parameters. Dynamic characteristics of a vehicle can vary with the change of these parameters. To investigate the effect of the design parameter on vehicle handling performance the sensitivity analysis is carried out by the numerical method. The vehicle model is described by equivalent cornering stiffness that considers parameters of suspension and steering system. As the analysis results show the effect on the static and dynamic characteristics of the vehicle system, the sensitivity analysis can be used for synthesis of the design parameters to improve the vehicle handling characteristics at the design stage as well as during the vehicle test under development.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.113-118
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• 1998

1994년 7월 25일 발생한 황해남부 지진(Mb=5.5)의 지진원 요소들을 결정하였다. 지진원 요소들을 결정하기 위하여 이 지진에 대하여 이전의 연구에서 얻어진 지진발생기구를 사용하였다. 지진발생기구에 의하면, 이 지진은 거의 동서방향의 압축응력장에 주향이동성분이 가미되어 발생한 것을 암시한다. 지진원 요소들은 단주기 및 장주기 P파에 대한 원지장 스펙트럼으로부터 계산되었다. 지진모멘트(M0), 코너주파수(f0), 지진원 반경(r) 및 응력강하량($\Delta$$\sigma$)은 각각 M0 = 3.18$\times$1024 dyne-cm, f0=0.3 Hz, r=3.7km, $\Delta$$\sigma$=27bar로 구해졌다. 지진모멘트로부터 산정한 모멘트 규모는 5.6으로 나타났다.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.33-39
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• 2006

Parameters including the seismic sources and the elastic wave propagation characteristics were analysed using the observed ground motions from 3 Kyoungju region earthquakes. The Levenberg-Marquardt algorithm was applied to invert all the variables non-linearly and simultaneously with S wave energy In frequency domain. Average stress drop of 3 events and local attenuation parameter ${\kappa}$ were estimated to about 48-bar and 0.0312 respectively. Regional attenuation parameter, Qo and ${\eta}$, were also estimated to be about 417 and 0.83. ${\kappa}$ values are much higher than that of EUS, even though smaller than that of WUS. All these values resultant from this study show that there are differences in some parameters of other studios due to differences in the governing equation. of acceleration motions

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.1 s.4
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• pp.135-141
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• 2002

Both non-linear damping values of the deep and shallow crustal materials and seismic source parameters are found from the observed near-field seismic ground motions at the South-eastern Korean Peninsula. The non-linear numerical algorithm applied in this study is Levenberg-Marquadet method. All the 25 sets of horizontal ground motions (east-west and north-south components at each seismic station) from 3 events (micro to macro scale) were used for the analysis of damping values and source parameters. The non-linear damping values of the deep and shallow crustal materials were found to be more similar to those of the region of the Western United States. The seismic source parameters found from this study also showed that the resultant stress drop values are relatively low compared to those of the Western United Sates. Consequently, comparisons of the various seismic parameters from this study and those of the United States Seismo-tectonic data suggest that the seismo-tectonic characteristics of the South eastern Korean Peninsula is more similar to those of the Western U.S.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.7
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• pp.26-31
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• 2005

In this paper, a small BPF(band pass filter) is designed using new probe type for wireless communication system. The dielectric resonator is used high Q ceramics for low loss characteristic. In order to provide a band pass filter which can be reduced in dimension, can be reduced in height, and can be surface-mounted. The filter was fabricated using $TE_{01{\delta}}$ mode dielectric resonator. The input/output probes are attached to coner portion of the rectangular metal cavity. Results of the manufactured filter($12{\times}12{\times}8[mm]$) show that the center frequency is 9.95358[GHz], the insertion loss is -1.9[dB], the 3[dB]_bandwidth is 14.9[MHz], and the loaf Q is 664.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.138-144
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• 2008

In this paper, we propose a novel single-feed dual-band circular polarization square patch antenna for GPS(global positioning system)/DMB(digital multimedia broadcasting) receiver. The proposed antenna has folded slots at the 4 corners and a diagonal slot at the center of the square patch. The measured -10 dB impedance bandwidths of the proposed antenna were 84 MHz ranging from 1.516 GHz to 1.600 GHz for the low frequency band(GPS) and 109 MHz ranging from 2.596 GHz to 2.705 GHz for the high frequency band(DMB). The measured peak linear antenna gains of the proposed antenna were 6.23 dBi at 1.575 GHz for GPS and 6.97 dBi at 2.642 GHz for DMB band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.430-439
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• 2006

This paper presents the a measured path-loss characteristics for mobile communications beyond 3G in microcellular residential area and street microcell at 3.4, 5.3, and 6.4 GHz band signals. The residential area is divided into two sections, one of which is composed of fifteen-story appartment buildings. The other section comprises four-story houses. The street microcell is classified line-of-sight(LOS) and nonline-of-sight(NLOS) areas. Both residential areas have standard deviations independent of the residential area classification, whereas the path loss exponents in the apartments is higher than those in area for same frequencies. A two-ray model is applied to analyse the path-loss charateristics in LOS areas. In LOS areas, an empirical breakpoint, whose distance is 6 percent shorter than a theorical breakpoint, is founded. Further, a sudden power level drop occurs at a transition point from LOS region to NLOS area. Path loss exponent is found to be significantly higher for non-LOS region than for LOS region. The power level drop due to corner loss and path-loss exponents both increase as the distance between the transmitter and the corner increases.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.1 s.53
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• pp.89-97
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• 2007

Parameters including the seismic sources and the elastic wave propagation characteristics were analysed using the observed ground motions from 12 Fukuoka region earthquakes. The Levenberg-Marquardt algorithm was applied to invert all the variables non-linearly and simultaneously with S wave energy in fiequency domain. Average stress drop of 12 events and local attenuation parameter $\kappa$ under seismic stations were estimated to about 79.2-bar and 0.043 respectively. Regional attenuation parameter, Qo and ${\eta}$, were also estimated to be about 248.1 and 0.558 respectively. Low value of Qo seems to caused by inhomogeneous tectonic characteristics between Japan island and southern Korean peninsula. $\kappa$ values are much higher than that characterizing EUS (Eastern United States) region, and nearly similar to that of WUS (Western Waited States) region. If the informations on site specific amplification of all the seismic stations are known, $\kappa$ values can be estimated more precisely. All the values including the seismic sources and the site and crustal scale propagation characteristics can be used as seismic design parameters.