• 제목/요약/키워드: Noise Power Spectrum

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사용후 핵연료 취급장비의 내진해석 (A Seismic Analysis of Spent Fuel Handling Tool)

  • 김성종;이영신;김재훈;김남균
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 춘계학술대회논문집
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    • pp.1210-1215
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    • 2002
  • The spent fuel handling tool is used to handle the refuel bundle and treated by hoist rope on the bridge crane. The new developed handling tool of NPP(Nuclear Power Plant) should be conformed the structural stability under earthquake condition. In this study, the stress and seismic analysis of the handling tool are performed by finite element method. Using the Floor Response Spectrum(FRS) obtained through the time history analysis, the modal and seismic analysis under Operating Basis Earthquake(OBE) and Safe Shutdown Earthquake(SSE) load conditions are carried out. Total 4 cases of different locations of the trolly and the hook are investigated. With the spring-damper element, the tension analysis of hoist rope is conducted. The stability of handling tool under earthquake load condition is conformed with regulatory guide.

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상용 유한요소해석 프로그램을 이용한 축류송풍기의 내진해석 (Seismic Analysis of an Axial Blower Using a Commercial FEM Code)

  • 정진태;임형빈;김강성;허진욱
    • 한국소음진동공학회논문집
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    • 제12권3호
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    • pp.181-186
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    • 2002
  • A seismic analysis is one of crucial design procedures of an axial blower used in nuclear power Plants. The blower should be operated even in ar emergency such as an earthquake. The blower should be designed in order to stand against an earthquake. For the seismic analysis, Ive perform the modal analysis and then evaluate the required response spectrum (PRS) from the given floor response spectrum (FRS). A finite element model of the blower is established by using a commercial FEM code of ANSYS. After the finite element modeling. the natural frequencies. the mode shapes and the participation factors are obtained from the modal analysis. The PRS is acquired by a numerical approach on the basis of the principle of mode superposition. We verify the structura safety of the axial blower and confirm the validity of the present seismic analysis results.

회절을 고려한 수도권 서북부 지역에서 GPS L1 C/A 신호의 재밍영향분석 (Jamming Effects of GPS L1 C/A Signal by Knife-Edge Diffraction Loss at Seoul Metropolitan Northwestern Region)

  • 유승수;김선용
    • 한국통신학회논문지
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    • 제38C권9호
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    • pp.757-763
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    • 2013
  • 본 논문에서는 수도권 서북부 지역의 3차원 지리정보를 바탕으로 다중예봉모형을 (multiple knife-edge model) 적용해 전파교란기와 수신기의 지리적 위치에 따른 회절손실을 (diffraction loss) 계산하고, 이를 바탕으로 광대역 잡음재밍 (wideband Gaussian null-to-null noise jamming), 스펙트럼일치형재밍 (matched spectrum jamming), 연속파재밍에 (continuous wave jamming) 의한 GPS (global positioning system) L1 C/A (coarse/acquisition) 신호의 여유재밍전력을 (marginal jamming power) 보인다.

평판에 충돌하는 원형분류의 공력소음에 관한 실험적 연구 (Au Experimental Study on the Aerodynamic Noise by a Circular Jet Impinging on a Plate)

  • 이동훈;권영필;한희갑
    • 소음진동
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    • 제7권1호
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    • pp.71-79
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    • 1997
  • The objective of this study is to investigate experimentally the effect of surface conditions of the plate on the impinging jet noise. The experimental results about the spectrum, the sound pressure level and the directivity are pressented and discussed in relation with the surface conditions. Regardless of the surface conditions, the pure tones of high level are generated at the same frequency band and the overall sound power level of impinging jets is much higher than that of the free jet. However, the velocity dependence of the sound pressure level and the directivity are different between smooth surfaces and rough surfaces. The dependence of sound pressure level on the jet velocity shows that the smooth surface generates quadrupole-type sound like free jets. However, the perforated or the rough surface radiates sound power exactly proportional to the sixth power of the jet velocity, indicating that the source is fixed dipole type. The directivities of 1/3 octave band sound pressure level for both the free and impinging jet show the peak directivity at 115$^\circ$ upstream, probably due to the refraction associated with velocity gradient.

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시스템 전자 냉각 팬의 선정 및 소음 평가 기법 (Selection and Noise Evaluation Methods of the System Electronic Cooling Fan)

  • 이찬;윤재호;권오경
    • 한국유체기계학회 논문집
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    • 제10권3호
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    • pp.33-38
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    • 2007
  • Fan selection procedure and fan noise evaluation method are presented for the system electronic cooling by combining FNM(Flow Network Model) and fan noise correlation model. Internal flow paths and distribution in electronic system we analyzed by using the FNM with the flow resistances for flow elements of the system. Based on the fan operation point predicted from the FNM analysis results, the present fan noise model predicts overall sound power, pressure levels and spectrum. The predictions of the flow distribution, the fan operation and the noise level in electronic system by the present method are well agreed with 3-D CFD and actual test results.

기계잡음 환경에서의 배관 누설탐지기법에 관한 연구 (A Study on Leak Detection Technique of a Pipe In a Noisy Environment)

  • 윤두병;박진호;신성환
    • 한국음향학회지
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    • 제31권7호
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    • pp.449-460
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    • 2012
  • 발전소 건설 시에 설치된 지하매설 배관이 대부분 20년 이상 경과됨에 따라서 지하매설 배관의 누설탐지의 중요성이 점차 부각되고 있다. 본 논문의 목적은 발전소와 같이 매설배관 주변에 회전체 기계잡음이 존재하는 경우에 배관의 누설위치 추정성능을 개선하기 위한 방법을 연구하는 것이며, 이러한 목적을 달성하기 위하여 주파수영역에서 배관 주변의 회전체 기계잡음을 효과적으로 제거할 수 있는 방법을 제안하였다. 또한 상호스펙트럼의 위상정보를 이용하여 배관의 누설위치를 추정하는 방법을 제안하였다. 제안된 방법의 타당성 평가를 위하여 실험을 수행하였으며, 실험결과 회전체에서 발생하는 주기적인 잡음성분을 제거함으로써, 배관 누설을 탐지하는 상호상관함수기법의 성능을 개선할 수 있음을 확인하였다.

퍼셉트론 신경회로망을 사용한 유성음, 무성음, 묵음 구간의 검출 알고리즘 (Voiced-Unvoiced-Silence Detection Algorithm using Perceptron Neural Network)

  • 최재승
    • 한국전자통신학회논문지
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    • 제6권2호
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    • pp.237-242
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    • 2011
  • 본 논문에서는 다층 퍼셉트론 신경회로망을 사용하여 각 프레임에서의 유성음, 무성음, 그리고 묵음 구간을 검출하는 구간검출 알고리즘을 제안한다. 다층 퍼셉트론 신경회로망의 입력으로는 고속 푸리에변환에 의한 전력스펙트럼 및 고속 푸리에변환 계수가 사용되어 네트워크가 학습된다. 본 실험에서는 원 음성에 백색잡음이 중첩된 음성을 신경회로망에 입력함으로서 각 프레임에서의 유성음, 무성음, 묵음 구간의 검출성능 결과를 나타낸다. 본 실험에서는 신경회로망의 학습 데이터 및 평가 데이터가 다를 경우에도 이러한 음성 및 백색잡음에 대하여 92% 이상의 검출율을 구할 수 있었다.

스펙트럼 확산 통신방식을 이용한 타국간 간섭제거 비동기 부호 분할 LAN의 구성 (Construction of LAN Using Asynchronous Code Division Multiplexing by Spread Spectrum Technique and a New Scheme of Cancelling Co-channel Interference)

  • 이동욱;변건식;김명기
    • 한국통신학회논문지
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    • 제14권6호
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    • pp.729-743
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    • 1989
  • 스펙트럼 확산 통신은 협대역 간섭 및 임펄스성 잡음등에 강하고 비화성이 있는등 많은 장점이 있어 비동기 부호분할 다중접속을 실현하는데 많은 이점을 갖고 있다. 본 논문은 이들 장점을 이용하여 LAN을 구성하는데 전용선 및 전원선과 같은 전송로를 사용했을 때의 LAN구성을 시도하였다. 그러나 전원선은 제한된 대역 때문에 부호분할 다중을 만들기 어려우며 결국 원근문제나 타국간 간섭을 받게 된다. 이의 주원인은 부호분할 다중시 사용되는 의사 잡음 부호의 상호상관의 불량 때문이다. 이 타국간 간섭을 제거할 수 있는 한가지 방법을 제안한고 스펙트럼 확산 기술을 사용한 LAN을 구성하기 위한 성능을 평가한 것이다.

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Modulation Recognition of BPSK/QPSK Signals based on Features in the Graph Domain

  • Yang, Li;Hu, Guobing;Xu, Xiaoyang;Zhao, Pinjiao
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제16권11호
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    • pp.3761-3779
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    • 2022
  • The performance of existing recognition algorithms for binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) signals degrade under conditions of low signal-to-noise ratios (SNR). Hence, a novel recognition algorithm based on features in the graph domain is proposed in this study. First, the power spectrum of the squared candidate signal is truncated by a rectangular window. Thereafter, the graph representation of the truncated spectrum is obtained via normalization, quantization, and edge construction. Based on the analysis of the connectivity difference of the graphs under different hypotheses, the sum of degree (SD) of the graphs is utilized as a discriminate feature to classify BPSK and QPSK signals. Moreover, we prove that the SD is a Schur-concave function with respect to the probability vector of the vertices (PVV). Extensive simulations confirm the effectiveness of the proposed algorithm, and its superiority to the listed model-driven-based (MDB) algorithms in terms of recognition performance under low SNRs and computational complexity. As it is confirmed that the proposed method reduces the computational complexity of existing graph-based algorithms, it can be applied in modulation recognition of radar or communication signals in real-time processing, and does not require any prior knowledge about the training sets, channel coefficients, or noise power.

강체 운동 해석을 통한 엔진의 가속도 예측 (Predict the engine Acceleration by Analyzing the Rigid Body Motion)

  • 김병현;박종호;이상권
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2011년도 춘계학술대회 논문집
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    • pp.351-356
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    • 2011
  • Some materials show the character of rigid body in low frequency spectrum. The rigid body motions are consisted of translational and rotational motions. Especially, we can get the acceleration or displacement of a random point in the rigid body by analyzing rigid body transfer matrix at the car's engine and power train. Actually it is difficult to measure the acceleration by attaching the sensor inside of the engine and power train. So the hard to predict acceleration data can be achieved attaching the sensor on the outside of the engine and power train by analyzing the data of rigid body motion which the engine is operated using dynamo. Also this paper will show the change of predicted data and accuracy variation by not using all the measured data but a few exceptions of the point number.

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