• Geophysics and Geophysical Exploration
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• v.14 no.4
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• pp.274-281
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• 2011

We analysed ground motions form Mw 4.3 earthquake around Backryoung Island for the seismic source focal mechanism and horizontal response spectrum. Focal mechanism of the Backryoung Islands area was compared to existing principal stress orientation of the Korean Peninsula and horizontal response spectrum was also compared to those of the US NRC Regulatory Guide (1.60) and the Korean National Building Code. The ground motions of 3 stations, including vertical, radial, and tangential components for each station, were used for grid search method of moment tensor seismic source. The principal stress orientation from this study, ENE-WSW, is consistent fairly well with that of the Korean Peninsula. The horizontal response spectrum using 30 observed ground motions analysed and then were compared to both the seismic design response spectra (Reg Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings (1997). Response spectrum of 30 horizontal ground motions were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that the horizontal response spectrum revealed higher values for frequency bands above 3 Hz than Reg. Guide (1.60). The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the vertical response spectra revealed higher values for the frequency bands below 0.8 second than the Korean Standard Response Spectrum (SD soil condition). However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of horizontal seismic design response spectrum should be considered more significantly for the higher frequency bands.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.6
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• pp.687-695
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• 2021

With the recent occurrence of large-scale earthquakes in Korea, the importance of seismic design has greatly increased. Seismic design standards stipulate that dynamic time history analysis be performed for important or special structures. In the seismic analysis and design of such structures, determining a rational design input seismic wave is a very important factor in ensuring the reliability of the analysis and design. In the seismic design standards, rational design seismic waves must reflect the characteristics of the area (fault) and satisfy the design response spectrum for each seismic performance level. This requirement can be partially satisfied by modifying the actual seismic wave measured in the area (fault) according to the design response spectrum. In this study, a method of correcting and generating seismic wave time histories according to the design response spectrum based on actual measured seismic waves using the harmonic wavelet transform was proposed. To examine the applicability of the proposed technique, the technique was applied to earthquakes of magnitude 5.8 and 5.4, respectively, that occurred in Gyeongju (2016) and Pohang (2017), and the seismic wave time histories corresponding to the design response spectrum were modified and generated.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.21-33
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• 2020

Ground response analysis has been conducted for each borehole data in Pohang area, using 1D equivalent linear method program, to investigate the applicability of amplification factor to estimate peak ground acceleration. Earthquake motions for ground response analysis were prepared by matching response spectrums for return period of 500, 1000, and 2400 years suggested by seismic design code (MOIS, 2017). Ground survey data were acquired from Geotechnical Information DB System. It has been confirmed that response spectrum obtained from ground response analysis showed good agreement with those from seismic design code irrespective of ground classification. However, PGA (Peak Ground Accelerations) of ground response analysis did not coincide with PGA calculated using amplification factor suggested by seismic design code.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.4
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• pp.442-449
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• 1986

본 연구에서는 소음원 및 진동원을 규명하기 위하여 사용되어 온 종래의 주파 수응답함수(Frequency Response Function`FRF)법과 소음원 및 진동원 간에 강한 상관 관계가 존재한 경우에 사용되는 기여도함수(coherence function)법을 이용한 다차원 스텍트럼해석(Multi-Dimensional Spectral Analysis`MDSA)법에 의하여 가속도응답 및 방사음과의 기여관계를 규명하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.19-20
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• 2017

본 논문은 사용자제작콘텐츠 (User Created Contents, UCC)를 이용한 가상현실 (virtual reality, VR) 음향 재구성을 위한 스마트폰의 주파수응답 정규화에 관한 연구이다. 서로 다른 스마트폰들로 취득한 음향들을 연결할 때, 부자연스러운 음향이 발생하며, 이것은 주로 스마트폰별로 다른 주파수 응답에 기인한다. 이러한 문제를 해결하기 위하여 스마트폰의 주파수응답을 정규화 하는 과정이 필요하며, 본 연구에서는 심층신경망 (deep neural network)을 이용하는 방법을 제안한다. 심층신경망의 입력은 처리하고자 하는 스마트폰 음향의 스펙트럼이고 출력은 이것과 기준 스마트폰 음향의 스펙트럼과의 비율이다. 실험결과, 서로 다른 스마트폰으로 취득한 음향신호가 연결되었을 때, 객관적 및 주관적 평가를 통해 음향의 자연성이 개선됨을 확인 하였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.1
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• pp.77-88
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• 2000

복소모드 중첩법은 점탄성 감쇠기가 설치된 비비례 감쇠시스템의 정확한 동적 거동을 예측할 수 있는 방법이지만 많은 자유도를 갖는 고층건물의 해석시 고유치 해석과 모드중첩과정에서 많은 시간과 노력이 필요하게 된다. 본 논문에서는 효율적인 모형화를 위하여 강막가정과 행렬응축기법을 적용하고 구조물의 진동에 영향을 주는 주요모드의 선택을 위한 복소모드 응답참여계수를 제안하므로써 복소모드 중첩법의 효율성은 높였다. 또한 비비례 감쇠시스템에서 감쇠를 고려하여 응답스펙트럼을 재구성한후 선택된 주요 모드를 중첩하여 최대층간변위가 발생하는 곳에 감쇠기를 설치하였다 이 방법은 감쇠기가 설치된 구조물에 대하여 만족되는 수준의 최대층간변위가 발생할 때 까지 고유치 해석만을 반복.수행하면서 감쇠기를 연속적으로 설치하는 방법이다. 제안된 방법의 정확성과 효율성을 검토하기 위하여 예제 구조물의 대상으로 해석한 결과 응답의 정확성을 유지하면서 해석에 필요한 시간을 대폭 절감할 수 있었다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.8
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• pp.589-597
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• 2002

In this paper the nonstationary response of accelerating vehicle is firstly obtained by using nonstationary road roughness model in time domain. To get the result of nonstationary response in frequency domain, the maximum entropy method is used for Processing nonstationary response of vehicle in frequency domain. The three-dimensional transient maximum entropy spectrum (MES) of response is given.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.195-206
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• 2011

The capacity spectrum method(CSM) has been more frequently used as a tool to evaluate the seismic capacity of the structure. Many formulas of strength reduction factors(SRF) have been proposed and adopted to generate the inelastic demand spectrum for the CSM. This study evaluates the impacts of the type of the SRF on the inelastic demand spectrum and finally on the seismic response displacement of curved bridge. For the purpose, the several existing formulas of SRFs were comparatively investigated through the case study. Curved bridges with different subtended angles were selected and the displacements of the bridge piers were estimated by using the different formulas of SRFs. Nonlinear time history analyses were also performed for the validation purpose of the CSM results. According to study results, the CSM may generate the larger displacement responses than the actual behaviors for the curved bridge with larger subtended angles. Though many methods have been suggested to generate the inelastic demand spectrum for CSM, they might not give noticeable differences in inelastic displacement of the bridge pier.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.5
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• pp.67-73
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• 2003

The present seismic analysis of Road-Bridge Design Standard is on a basis of load-based analysis which lets structures have the strength over load. In this study, the capacity spectrum method, a kind of displacement based method, which is evaluated by displacement of structure, is presented as an alternative to the analysis method based on load. Seismic capacity is performed about the existing reinforced concrete pier which has already secured seismic design by capacity spectrum method. As a result. capacity spectrum method could realistically evaluate the non-elastic behavior of structures easily and quickly and the displacement of structures for variable ground motion level. And it could efficiently apply to an evaluation of seismic capacity about the existing structure and a verification of design for capacity target of the new structure.

• Nuclear industry
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• v.22 no.2 s.228
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• pp.31-33
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• 2002