• Title/Summary/Keyword: Amplification ratio

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A Basic Study on the Influence of an Understructure on the Seismic Response of a Spatial Structure (공간구조의 지진응답에 대한 연구 하부구조의 영향에 관한 기초적 연구)

  • Jung, Chan-Woo;Jung, Hwan-Mok
    • Proceeding of KASS Symposium
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    • 2005.05a
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    • pp.215-226
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    • 2005
  • To study the influence of an lower part on the seismic response of a spatial structure as the upper part of a structure, as a first step, authors subsititude the upper part and the lower part of a structure to single degree of freedom systems indivisually, and set up structural models connected by them. It is clarified that the mass ratio and the period ratio of an upper part to a lower part are important parameteres to find the amplification or reduction of the sesimic response of an upper part by considering of a lower part.

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Effects of excitation characteristics on the equivalent linear system of a building structure with MR dampers (MR감쇠기가 설치된 구조물의 등가선형 시스템에 대한 가진 특성의 영향)

  • Park, Ji-Hun;Min, Kyung-Won;Moon, Byoung-Wook;Park, Eun-Churn
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2006.03a
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    • pp.503-510
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    • 2006
  • Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with an MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with an MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed.

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A Design of Predistortion HPA using Frequency Up-Conversion Mixing Operation (주파수 상향 변환을 이용한 전치왜곡 전력 증폭기 설계)

  • Jeong, Yong-Chae;Kim, Young;Kim, Chul-Dong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.5
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    • pp.480-485
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    • 2004
  • In this paper, a new predistortion linearizing method using frequency up-conversion operation of mixer is proposed. This linearizing method doesn't require any additional signal sources in spite of frequency up-conversion mixing operation. This method extracts the 2nd low frequency intermodulation distortion signal from input signals and uses the extracted 2nd low frequency intermodulation distortion signal as mixing signal source. To show validation of the proposed predistortion method, we made K-PCS power amplifier. On 2-tone signals amplification process, the (C/I) ratio of amplifier is improved 26 ㏈ (@Po=22 ㏈m/tone), where two tones are 1.8544 ㎓ and 1.8556 ㎓, respectively. And (C/I) ratio is improved more than to 20 ㏈ for 17 ㏈ output signal dynamic range. On IS-95A CDMA 1FA amplification process, the improvements of adjacent channel power ratio(ACPR) are 10.8 ㏈ and 6.4 ㏈ at ${\pm}$885 ㎑ and ${\pm}$1.25 ㎒ offset points, respectively.

Analysis of Consistency and Accuracy for the Finite Difference Scheme of a Multi-Region Model Equation (다영역 모델 방정식의 유한차분계가 갖는 일관성과 정화성 분석)

  • 이덕주
    • Journal of Korea Soil Environment Society
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    • v.5 no.1
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    • pp.3-12
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    • 2000
  • The multi-region model, to describe preferential flow, is an equation representing solute transport in soils by dividing soil into numerous pore groups and using the hydraulic properties of the soil. As the model partial differential equation (PDE) is solved numerically with finite difference methods. a modified equivalent partial differential equation(MEPDE) of the partial differential equation of the multi-region model is derived to analyze the accuracy and consistency of the solution of the model PDE and the Von Neumann method is used to analyze the stability of the finite difference scheme. The evaluation obtained from the MEPDE indicated that the finite difference scheme was found to be consistent with the model PDE and had the second order accuracy The stability analysis is performed to analyze the model PDE with the amplification ratio and the phase lag using the Von Neumann method. The amplification ratio of the finite difference scheme gave non-dissipative results with various Peclet numbers and yielded the most high values as the Peclet number was one. The phase lag showed that the frequency component of the finite difference scheme lagged the true solution. From the result of the stability analysis for the model PDE, it is analyzed that the model domain should be discretized in the range of Pe < 1.0 and Cr < 2.0 to obtain the more accurate solution.

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Equivalent damping ratio based on earthquake characteristics of a SDOF structure with an MR damper (지진특성에 따른 MR 감쇠기가 설치된 단자유도 구조물의 등가감쇠비)

  • Moon, Byoung-Wook;Park, Ji-Hun;Lee, Sung-Kyung;Min, Kyung-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.459-464
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    • 2007
  • Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

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Equivalent damping ratio based on the earthquake response of a SDOF structure with a MR damper (MR 감쇠기가 설치된 단자유도 구조물의 지진응답에 기초한 등가감쇠비)

  • Park, Ji-Hun;Moon, Byoung-Wook;Min, Kyung-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.879-885
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    • 2006
  • Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

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Improvement of extinction ratio of amplified pulses by incorporating a nonlinear optical loop mirror (EDFA로 증폭된 고출력 펄스 신호의 소광비 향상)

  • Kim, Byung-Jun;Choi, Hyun-Beom;Lee, Han-Hyub;Lee, Dong-Han;Kim, Dae-Yun;Kwon, Il-Bum
    • Korean Journal of Optics and Photonics
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    • v.14 no.2
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    • pp.189-193
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    • 2003
  • A two-stage erbium-doped fiber amplifier (EDFA) with a band pass filter is used to get optical pulses of high peak value. The pulse signal has a 32 ㏈ extinction ratio, 125 W peak power and 79 ㎽ pulse off power. A nonlinear optical loop mirror (NOLM) is used to lower the pulse off power so as to increase the extinction ratio. The pulse signal after the NOLM has a 50.4 ㏈ extinction ratio, 35 W peak power and 0.3 ㎽ pulse off power.

Equivalent Damping Ratio Based on Earthquake Characteristics of a SDOF Structure with an MR Damper (지진특성에 따른 MR감쇠기가 설치된 단자유도 구조물의 등가감쇠비)

  • Moon, Byoung-Wook;Park, Ji-Hun;Lee, Sung-Kyung;Min, Kyung-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.1
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    • pp.87-93
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    • 2008
  • Seismic control performance of MR dampers, which have severe nonlinearity, varies with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally. response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

Image Enhancement Method by Saturation and Contrast Improvement

  • Park, Gyu-Hee;Cho, Hwa-Hyun;Yun, Jong-Ho;Choi, Myung-Ryul
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08b
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    • pp.1139-1142
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    • 2007
  • In this paper, an image enhancement method by saturation and contrast improvement is proposed. Histogram equalization with color difference makes higher contrast. By generating saturation amplification ratio with color difference, the saturation improves effectively. The experimental results show that the proposed algorithm has higher contrast and more natural - look than the conventional methods.

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Recent Progress of Freak Wave Prediction

  • Mori, Nobuhito;Janssen, Peter A.E.M.
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2006.11a
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    • pp.127-134
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    • 2006
  • Based on a weakly non-Gaussian theory the occurrence probability of freak waves is formulated in terms of the number of waves in a time series and the surface elevation kurtosis. Finite kurtosis gives rise to a significant enhancement of freak wave generation in comparison with the linear narrow banded wave theory. For fixed number of waves, the estimated amplification ratio of freak wave occurrence due to the deviation from the Gaussian theory is 50% - 300%. The results of the theory are compared with laboratory and field data.

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