• 한국지진공학회논문집
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• 제25권1호
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• pp.43-52
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• 2021

According to several seismic design standards, a ground motion time history should be selected similar to the design response spectrum, or a ground motion time history should be modified by matching procedure to the design response spectrum through the time-domain method. For the response spectrum matching procedure, appropriate seed ground motions need to be selected to maintain recorded earthquake accelerogram characteristics. However, there are no specific criteria for selecting the seed ground motions for applying this methodology. In this study, the characteristics of ground motion time histories between seed motions and spectral matched motions were compared. Intensity measures used in the design were compared, and their change by spectral matching procedure was quantified. In addition, the seed ground motion sets were determined according to the response spectrum shape, and these sets analyzed the response of nonlinear and equivalent linear single degrees of freedom systems to present the seed motion selection conditions for spectral matching. As a result, several considerations for applying the time domain spectral matching method were presented.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.214-224
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• 1999

The design response spectrum has been widely used in seismic design to estimate force and deformation demands of structures imposed by Earthquake Ground Motion (EQGM). Inelastic Design Response Spectra (IDRS) to specify design yielding strength in seismic codes are obtained by reducing the ordinates of Linear Elastic Design Response Spectrum (LEDRS) by strength reduction factor (R). Since a building is designed using reduced design spectrum (IDRS) rather than LEDRS in current seismic design procedures it allows structures behave inelastically during design level EQGM. Inelastic Response Spectra (IRS) depend not only on the characteristics of the expected ground motion at a given site, but also on the dynamic properties and nonlinear characteristics of a structure. However, it has not been explicitly investigated the effect of different hysteretic models on IRS. In this study, the effect of hysteretic models on IRS is investigated.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.1805-1810
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• 2014

본 논문에서는 BPSK 변조 방식과 50 kbps 저속 데이터 전송모드를 사용하는 원격제어 장치의 위상잡음 스펙트럼 분포를 설계하고 제시하였다. FSK 전송 방식보다 전송 성능이 우수한 BPSK 방식을 적용할 경우, 위상잡음에 의한 열화가 발생한다. 위상잡음에 의한 열화를 최소화하기 위해서는 요구 위상잡음을 갖는 채널 환경에서 신호를 전송하는 것이 중요하다. 요구 위상잡음 환경에 적합한 채널 환경 및 단말 장치 구현을 위하여 요구 성능을 만족하는 위상잡음 스펙트럼 분포를 설계한다. 위상잡음 설계 파라미터인 감쇠 정수와 잡음 대역폭에 대한 위상잡음 영향도를 해석하고 위상잡음 스펙트럼 분포 설계 파라미터로 적용하였다. IESS-308 위상잡음 특성을 기준으로 위상잡음 영향을 분석하고, 원격제어 장치에 적합한 위상잡음 스펙트럼 분포도와 설계 방법을 제시하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제24권5호
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• pp.27-36
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• 2020

이 논문의 목적은 말뚝식 계류시설에 대해 현행 실무에서 주로 적용하고 있는 응답스펙트럼 해석법에서 표준설계응답스펙럼의 적용성에 대해 연구하는 것이다. 이를 위하여 다양한 지층조건을 고려한 Proshake 1차원 부지응답을 수행하여 현행 표준설계응답스펙트럼과 비교하고, Abaqus를 활용한 지반-말뚝 모델링으로 시간이력해석을 수행하여 지반-말뚝 동적거동 특성을 분석하였으며, 잔교시설이 설치되는 경사지반에 대해 Abaqus를 활용한 2차원 부지응답해석을 수행하여 응답스펙트럼의 기준면 선정방안을 검토하였다. 연구 결과 말뚝식 계류시설의 지반-말뚝 동적거동 특성과 경사지반의 특성을 고려할 경우 현행 표준설계응답스펙트럼의 적용성에 문제가 있으며 개선이 필요하다는 것을 확인하였다.

• 한국지진공학회논문집
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• 제27권1호
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• pp.69-75
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• 2023

In Korea, most nuclear power plants were designed based on the design response spectrum of Regulatory Guide 1.60 of the NRC. However, in the case of earthquakes occurring in the country, the characteristics of seismic motions in Korea and the design response spectrum differed. The seismic motion in Korea had a higher spectral acceleration in the high-frequency range compared to the design response spectrum. The seismic capacity may be reduced when evaluating the seismic performance of the equipment with high-frequency earthquakes compared with what is evaluated by the design response spectrum for the equipment with a high natural frequency. Therefore, EPRI proposed the inelastic energy absorption factor for the equipment anchorage. In this study, the seismic performance of welding anchorage was evaluated by considering domestic seismic characteristics and EPRI's inelastic energy absorption factor. In order to reflect the characteristics of domestic earthquakes, the uniform hazard response spectrum (UHRS) of Uljin was used. Moreover, the seismic performance of the equipment was evaluated with a design response spectrum of R.G.1.60 and a uniform hazard response spectrum (UHRS) as seismic inputs. As a result, it was confirmed that the seismic performance of the weld anchorage could be increased when the inelastic energy absorption factor is used. Also, a comparative analysis was performed on the seismic capacity of the anchorage of equipment by the welding and the extended bolt.

• 대한토목학회논문집
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• 제28권1A호
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• pp.25-37
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• 2008

역량스펙트럼 방법은 그래픽적인 방법으로 간단하게 지진해석을 수행한다. 개발 초기에 역량스펙트럼 방법은 빌딩구조물에 주로 사용되었으나 최근에는 교량구조물에도 사용할 수 있도록 확장되었다. 역량스펙트럼 방법은 비탄성 정적해석으로부터 구한 역량곡선과 유효감쇠 혹은 강도감소계수를 사용하여 선형탄성 설계스펙트럼을 감소시켜 구한 요구도 스펙트럼에 기반을 두고 있다. 본 논문에서는 감소된 요구도 스펙트럼은 강도감소계수에 대한 몇 개의 제안식을 사용하여 구한 비탄성 요구도 스펙트럼을 사용한다. 역량스펙트럼 해석에 대한 강도감소계수의 영향은 세가지 종류의 대칭 및 비대칭 교량에 대하여 평가하였다. 몇 개의 강도감소계수를 적용한 역량스펙트럼 방법의 정확성을 평가하기 위하여, 역량스펙트럼 방법에 의한 최대변위를 8개의 인공지진에 의한 비탄성 시간이력해석 결과와 비교하였다. 강도감소계수 제안식 중 SJ 제안식에 의한 역량스펙트럼 해석의 최대변위가 비탄성 시간이력해석 결과와 가장 일치하는 결과를 나타냄을 알 수 있었다.

• Earthquakes and Structures
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• 제12권2호
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• pp.177-189
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• 2017

For energy-based seismic design, a simplified normalized cumulative hysteretic energy spectrum proposed for obtaining hysteretic energy as energy demand is the main objective in this paper. The dimensionless parameter, ${\beta}_{Eh}$, is presented to express hysteretic energy indirectly. The ${\beta}_{Eh}$ spectrum is constructed directly through subtracting the hysteretic energy of single degree-of-freedom (SDOF) system energy equation. The simplified ${\beta}_{Eh}$ spectral formulation as well as pseudo-acceleration spectrum of modern seismic provisions is developed based on the regression analysis of the large number of seismic responses of SDOF system subjected to earthquake excitations, which considers the influence of earthquake event, soil type, damping ratio, and ductility factor. The relationship between PGV and PGA is established according to the statistical analysis relied on a total of 422 ground motion records. The combination of ${\beta}_{Eh}$ spectrum and PGV/PGA equation allows determining the cumulative hysteretic energy as a main aseismic design indicator.

• Structural Engineering and Mechanics
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• 제27권2호
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• pp.173-197
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• 2007

A wavelet-based procedure to generate artificial accelerograms compatible with a prescribed seismic design spectrum is described. A procedure to perform a baseline correction of the compatible accelerograms is also described. To examine how the frequency content of the modified records evolves with time, they are analyzed in the time and frequency using the wavelet transform. The changes in the strong motion duration and input energy spectrum are also investigated. An alternative way to match the design spectrum, termed the "two-band matching procedure", is proposed with the objective of preserving the non-stationary characteristics of the original record in the modified accelerogram.

• 항공우주시스템공학회지
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• 제1권2호
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• pp.27-36
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• 2007

The Damage Tolerant Design is developed to help alleviate structural failure and cracking problems in aerospace structures. Recently, the Damage Tolerant Design is required and recommended for most of aircraft design. In this paper, the damage tolerant design is applied to tilt rotor UAV. First of all, the fatigue load spectrum for the tilt rotor UAV is developed and fatigue analysis is performed for the flaperon joint which has FCL (fatigue critical location). Tilt rotor UAV has two modes: helicopter mode when UAV is taking off and landing; fixed wing mode when the tilt rotor UAV is cruising. To make fatigue load spectrum, FELIX is used for helicopter mode. TWIST is used for fixed wing mode. Fatigue analysis of flaperon joint is performed using fatigue load spectrum. E-N curve approach is used for picking crack initiation point. The LEFM(Linear Elastic Fracture Method) is considered for analyzing crack growth or propagation. Finally, including the crack initiation and propagation, the fatigue life is evaluated. Therefore the Damage Tolerant Design can be done.

• 한국지진공학회논문집
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• 제21권6호
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• pp.277-286
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• 2017

On September 12, 2016, Gyeongju earthquake occurred. Its local magnitude was announced to be $M_L=5.8$ by Korea Meteorological Administration (KMA). Ground motion data recorded at KMA, EMC and KERC stations was obtained from their data bases. From the data, horizontal and vertical response spectra, and V/H ratio were calculated. The horizontal spectrum was defined as geometric mean spectrum, GMRotI50. From the statistical analysis of the geometric mean spectra, a mean plus one standard deviation spectrum in lognormal distribution is obtained. Regression analysis is performed on this curve to determine the shape of spectrum including transition periods. Applying the same procedure, the shape and transition periods of vertical spectrum was obtained. These results were compared with the Korean standard design spectra, which were developed from domestic and overseas intraplate earthquake records. The response spectra of Gyeongju earthquake were found to be almost identical with the newly proposed design spectra. Even the V/H ratios showed good agreement. These results confirmed that the method adopted when developing the standard design spectra were valid and the developed design spectra were reliable.