• Title, Summary, Keyword: incoherent

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Effect of the incoherent earthquake motion on responses of seismically isolated nuclear power plant structure

  • Ahmed, Kaiser;Kim, Dookie;Lee, Sang H.
    • Earthquakes and Structures
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    • v.14 no.1
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    • pp.33-44
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    • 2018
  • Base-isolated nuclear power plant (BI-NPP) structures are founded on expanded basemat as a flexible floating nuclear island, are still lacking the recommendation of the consideration of incoherent motion effect. The effect of incoherent earthquake motion on the seismic response of BI-NPP structure has been investigated herein. The incoherency of the ground motions is applied by using an isotropic frequency-dependent spatial correlation function to perform the conditional simulation of the reference design spectrum compatible ground motion in time domain. Time history analysis of two structural models with 486 and 5 equivalent lead plug rubber bearing (LRB) base-isolators have been done under uniform excitation and multiple point excitation. two different cases have been considered: 1) Incoherent motion generated for soft soil and 2) Incoherent motion generated for hard rock soil. The results show that the incoherent motions reduce acceleration and the lateral displacement responses and the reduction is noticeable at soft soil site and higher frequencies.

Incoherent Triangular holography using Mercury Lamp (수은등을 이용한 인코히어런트 삼각 홀로그래피)

  • 김수길
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.144-148
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    • 2000
  • We presented a modified triangular interferometer as an incoherent holography, which can eliminate bias and conjugate image problems of the conventional one. Also, to demonstrate the feasibility of incoherent holography, the formation of an incoherent hologram using a mercury lamp and its optical reconstruction were presented.

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A Basic Study on the Filtering of Incoherent Hologram (인코히어런트 홀로그램의 필터링에 관한 기초연구)

  • Kim, Soo-Gil
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.10
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    • pp.1-4
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    • 2010
  • It is proposed the basic filtering method to remove bias and conjugate image in incoherent hologram. To demonstrate the feasibility of the proposed method, the image reconstruction of incoherent hologram is presented.

Incoherent Inverse Scattering of 3-Dimensional Underground Cavity in Lossy Medium (손실 매질내에 있는 3차원 지하공동의 Incoherent 역산란)

  • 홍성용;강진섭
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.3
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    • pp.378-391
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    • 1999
  • When the time-harmonic plane wave is incident upon a high-contrast spherical cavity in a lossy medium, the incoherent shadow intensity pattern is acquired by averaging out the multi-frequency intensities of the co-polarized total electric field calculated at the measurement plane perpendicular to the propagating direction of the incident wave in the forward direction. In the spherical rotational measurement configuration, an incoherent imaging of the spherical cavity is obtained via the back-projections of the incoherent shadow intensity pattern. This imaging method is validated by imaging an air sphere in the lossy medium of ${\epsilon}_r$ = 2 and $\sigma$ = 0.001, 0.003 S/m and the conditions for obtaining better images are investigated.

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Microwave Incoherent Imaging of a Conducting Cylinder by Using Multi-Frequency Time-Harmonic Field : Part I - Incoherent Intensity Pattern by Using Multi-Frequency Time-Harmonic Field (다중주파수 시간좌화신호를 사용한 도체기중의 초고주파 incoherent 영상:Part I - 다중주파수 시간좌화신호를 사용한 incoherent 전력패턴)

  • 강진섭;라정웅
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.2
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    • pp.47-55
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    • 1996
  • A microwave incoherent imaging method for a conducting cyliner by using multi-frequency tiem-harmonic field is presented in this study. In this paper, an incoherent intensity pattern of th econducting cylinder is obtained by averagin gout the multi-frequency intensities of the coherent field such as the time-harmonic field scattered from this cylinder. This phenomenon is hsown numerically in scattering by a conducting circular cylinder illuminated by the time-harmonic plane wave, and is interpreted analytically by the mutual coherence functon defined as a frequency-averaged intensity of the time-harmonic fields in th frequency domain.

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Microwave Incoherent Imaging of a Conducting Cylinder by using Multi-Frequency Time-Harmonic Field : Part II - Microwave Incoherent Imaging of a Conducting Cylinder (다중주파수 시간조화신호를 사용한 도체기둥의 초고주파 incoherent 영상 : Part II - 도체기둥의 초고주파 incohernet 영상)

  • 강진섭;라정웅
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.2
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    • pp.56-64
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    • 1996
  • In the previous paper of this study, an incoherent intensity pattern of a conducting cylinder is obtained by averaging out the multi-frequency intensities of the time-harmonic fields scattered from this cylinder. in this paper, an incoherent imaging of a conducting cylinder is obtained via the back-projection of the incoherent intensity patterns calculated from the circular rotational measurement configuration. This imaging method is vlaidated by imaging a conducting circular and a conducting elliptic cylinder and the measurement conditions to get better image are investigated.

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Estimation of Incoherent Scattered Field by Multiple Scatterers in Random Media

  • Seo, Dong-Wook;Lee, Jae-Ho;Lee, Hyung Soo
    • ETRI Journal
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    • v.38 no.1
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    • pp.141-148
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    • 2016
  • This paper proposes a method to estimate directly the incoherent scattered intensity and radar cross section (RCS) from the effective permittivity of a random media. The proposed method is derived from the original concept of incoherent scattering. The incoherent scattered field is expressed as a simple formula. Therefore, to reduce computation time, the proposed method can estimate the incoherent scattered intensity and RCS of a random media. To verify the potential of the proposed method for the desired applications, we conducted a Monte-Carlo analysis using the method of moments; we characterized the accuracy of the proposed method using the normalized mean square error (NMSE). In addition, several medium parameters, such as the density of scatterers and analysis volume, were studied to understand their effect on the scattering characteristics of a random media. The results of the Monte-Carlo analysis show good agreement with those of the proposed method, and the NMSE values of the proposed method and Monte-Carlo analysis are relatively small at less than 0.05.

Incoherent Triangular Holography using Mercury Lamp (수은등을 이용한 인코히어런트 삼각 홀로그래피)

  • 김수길
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.15 no.1
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    • pp.22-27
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    • 2001
  • We presented a modified triangular interlerorreter as an incoherent holography, which can eliminate bias and conjugate image problems of the conventional one. Also, to demonstrate the feasibility of incoherent holograrphy, the formation of an incoherent hologram using a mercury lamp and its numerical and optical reconstructions were presented.sented.

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Acoustic Source Modeling by Using ISC(Inverse Source Calculation) (역 행렬 계산을 이용한 실 소음원의 모델링)

  • 최재웅;이희준;강종민;강신일
    • Journal of KSNVE
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    • v.8 no.3
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    • pp.542-552
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    • 1998
  • The noise sources, structure-borne and/or air-borne, in machinery can be defined by their locations and strengths. However the locations of that noise sources are well known in many cases. In those cases, the problem can be defined as an inverse problem to known the strengths of the noise sources in the frequency domain, the modeling scheme is classified by thecoherent or incoherent source. This paper expands the basic concept to the case of the complex noise sources, in which the set of coherent and incoherent noise sources are matched with the noise of a real vehicle. The error factors in the experiment and the optimal number of the monopole sources to match the real suond filed are also investigated. The results of the noise source modeling of heavy machinery show that the incoherent and coherent/incoherent source models are applicable to the high frequency and the low frequency region, respectively. The noise source model also enables the noise source analysis to rank the contribution of real source group such as engine, T/M, exhuast, etc.

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Incoherent Tomography for Conducting Cylinder by Using Single-Frequency Time-Harmonic Source (단일 주파수 시간조화 신호원을 사용한 도체기둥의 incoherent 단면영상법)

  • 강진섭;라정웅
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.1
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    • pp.1-7
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    • 1998
  • In this paper, an incoherent imaging of a conducting cylinder illuminated by the single-frequency time-harmonic plane wave is obtained via the back-projections of the intensity patterns of the forward total electric field scattered from this object in the circular rotational measurement configuration. The pheonmenon that interference fringes generated in the itesity patterns is removed in the back-projection process is interpreted numerically. This imaging method is validated by imagining conducting circular cylinders and the conditions to ge beter image are investigated.

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