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Kim, Jae-Chul;Moon, Kyeong-Ho
- Transactions of the Korean Society of Mechanical Engineers A
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- v.27 no.4
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- pp.531-536
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- 2003
In order to control the railway noise. we should know the radiation characteristic of the noise during the train passage Generally, the railway noise sources for conventional trains are classified by the rolling noise and power unit noise in tangent track. In this Paper. we describe on a train model that is considered to be a row of point sources to calculate the radiation characteristic The calculation results are compared with short distance measurement of three kinds of trains (EMU, Mookungwha, Saemaul). It is shown that the radiation characteristic of the rolling noise that is major noise source of electric multiple unit is dipole type. We know that characteristic of the engine noise is radiated as the cosine type.
https://doi.org/10.3795/KSME-A.2003.27.4.531 인용 KSCI

Wang, Ziye;Yang, Chun;Xu, Weijie
- Current Optics and Photonics
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- v.2 no.5
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- pp.395-399
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- 2018
This article investigates the mechanism of electronic signal phase noise degradation induced by laser phase noise in optical links comprising optical resonators. Through theoretical derivation, we find that the phase noise of the output electronic signal has the same spectral shape of optical intensity noise as the output of the optical resonator. We propose that the optical resonator transfers laser phase noise to light intensity fluctuation and then the intensity fluctuation is converted to electric phase noise through AM-PM conversion mechanism in the photodiode. An optical link comprising a Fabry-Perot resonator was constructed to verify the proposed mechanism. The experimental results agree with our theoretical prediction verifying that the supposition is correct.
https://doi.org/10.3807/COPP.2018.2.5.395 인용 PDF KSCI

Lee, Dong-Il;Sin, Gu-Yong;Kim, Jeong-Bu
- The Transactions of the Korean Institute of Electrical Engineers C
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- v.48 no.7
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- pp.542-549
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- 1999
Corona discharges form at the surface of a transmission line conductor when the electric-field intensity on the conductor surface exceeds the breakdown strength of air. In order to decrease the electric-field intensity on the conductor surface, a new 6 conductor bundle has been studied. This bundle, hybrid conductor bundle, consists of using a larger subconductor at the bottom two conductor positions in the 6-conductor bundles of each phase of the line. The electric field on these two larger subconductors is reduced which in turn reduces the corona noise. It is shown that this is a better solution for decreasing the electric-field intensity than ether the conventional bundle or the asymmetric bundle proposed by EPRI.
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