• Title/Summary/Keyword: Propagation loss

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Measurement of Dynamic Properties of Concrete Structures Using Beam Transfer Function Methods (보 전달함수법을 이용한 콘크리트 구조물의 동특성 측정)

  • Kim, Seung-Joon;Yoo, Seung-Yup;Jeong, Yeong;Jun, Jin-Yong;Park, Jun-Hong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.950-953
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    • 2006
  • The floor impact noise of concrete structures in apartments buildings is affected from the flexural wave propagation characteristics. Accordingly, the measurement of wave propagation characteristics is required for suggestion of efficient method to reduce the impact noise. The purpose of this article is to propose an experimental technique to measure dynamic properties of concrete structures. The method was proposed using the flexural wave propagation characteristics. Wave speeds, bending stiffness and their loss factors are estimated from which the vibration dissipation capabilities are investigated. Several different concrete beam structures were custom-built for measurement. The damping treatments using viscoelastic materials for reducing noise generation are also tested. The beam transfer function of the damped beam is predicted using the compressional damping model from which the mechanism of the vibration energy dissipation is investigated.

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A Study on Field Strength Prediction for the Band of Land Mobile Telephone Systems in Cheju Western Area (제주 서부지역의 이동 전화 주파수대의 전계강도 예측에 관한 연구)

  • 홍문식;김흥수
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.7
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    • pp.47-54
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    • 1994
  • The propagation prediction within a cell coverage in land mobile radio service is very important. The propagation loss is presented in a A+B logS110TR form, where both A and B are the parameter as function of the frequency and the antenna height and R is the distance of between base and mobile station. The propagation prediction is Cheju area is not easy, because a great number of peaks are found here and there at the foot of the Hanla Mt. The characteristics of radio propagation in Cheju area are measured for the Seorum transmitter site. The formular of correction which is regard to the configuration of the ground is presented, and the predicted values are compared with the measured one.

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Underwater Sound Propagation in a range-dependent Shallow water environment (비균질한 천해에서의 수중음파 전파)

  • Na, Jeong-Yeol
    • The Journal of the Acoustical Society of Korea
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    • v.6 no.4
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    • pp.64-73
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    • 1987
  • Low frequency sound propagation in a range-dependent shallow water environment of the Korea Strait has been studied by using the adiabatic coupled mode, ADIAB. The range-dependent environment is unique in terms of horizontal variations of sound velocity profiles, sediment thickness and attenuation coefficients and water depths. For shallow source and receiver depths, the most important mechanism involved in the propagation loss is the depth changing character of mode functions that strongly depends on the local sound velocity profile. Application of the adiabatic coupled mode theory to shallow water environment is reasonable when higher modes are attenuated due to bottom interaction effects. Underwater sound propagation in a range-dependent shallow-water environment.

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The Prediction and Analysis of the Propagation Characteristics in Indoor Environments Using the SBR/Image Method (SBR 및 영상기법을 이용한 실내 환경의 전파특성 예측과 분석)

  • 손호경;김채영;김성진
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.2
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    • pp.199-207
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    • 2001
  • In this paper, the technique of prediction and analysis on the characteristics of propagation in indoor environment is presented. This technique needs no reception sphere commonly used in 3D-ray tracing scheme, and thereby it lends us easy code realization. The validity of developed code is verified by comparing with the values of image methods and measurement. The developed technique applied to the structure of rectangular corridor with the iron door and we calculated the path loss for the variation of the iron door angle. The path loss decreased about 15 dB at the distance of30 m from the iron door and the delay spread increased approximately by four times. Based on the computation, we confirmed that indoor propagation in PCS is heavily affected by the iron door in corridor.

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Analysis of Arrayed Waveguide Grating Waveglength Filter using Wide Angle Beam Propagation Method (Wide Angle BPM 을 이용한 광도파로열 격자 파장 필터의 해석)

  • Park, Jun-O;Jeong, Yeong-Cheol
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.39 no.2
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    • pp.46-55
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    • 2002
  • The key component to accomplish the WDM all optical network is an Arrayed Waveguide Grating(AWG) wavelength filter Numerical analysis is necessary for design and analysis of optical components like AWG wavelength filter. Beam Propagation Method(BPM) is the most widely-used method. In this paper, we analyze the difference between the paraxial BPM and the WA-BPM when they are applied to the analysis of InP/InGaAsP/InP AWG wavelength filter. The paraxial BPM is based on paraxial approximation, and the WA-BPM is based on the low order Pade approximant. The side lobe level(SLL) and insertion loss calculated from both methods are compared. The high order Pade approximant will to used to more accurate design and analysis of AWG.

A Study on the High Strength of porcelain insulators for transmission line (송전용 자기재 현수애자의 고강도 특성 연구)

  • Cho, H.G.;Han, S.W.;Park, K.H.;Choi, Y.K.;Lee, D.I.;Choi, I.H.;Kim, T.Y.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05e
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    • pp.85-88
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    • 2003
  • In this study, porcelain insulator samples which have a different alumina composition were manufactured in order to test electrical and mechanical properties and make an analysis of the propagation phenomena of micro cracks on porcelain body. From XRD quantitative analysis the crystalline phases were different with alumina composition, sample C and D which have about 17wt% Corundum phase without the Cristobalite phase shows better electrical and mechanical properties than sample A and 8 which have the Cristobalite phase. In dielectrics test on porcelain samples with below 17wt% alumina composition, it was found that the amount of glass phase$(SiO_2)$have an main effect to decrease the dielectric loss$(tan{\delta})$, and the dielectric breakdown voltage of aluminous porcelain insulators was largely affected by its relative density. As a micro cracks analysis, HRS were measured, then the intensity of HRS increased with the amount of alumina composition. On the other hand, the propagation behaviors of cracks was fairly influenced by the distribution of pores.

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Variability of Underwater Sound Propagation in the Northern Part of the East Sea (동해 북부해역의 수중음파전달 변동성)

  • Lim, Se-Han;Yun, Jae-Yul;Kim, Yun-Bae;Nam, Sung-Hyun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.4
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    • pp.52-61
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    • 2007
  • Temporal and spatial variations of sea water largely affect on the pattern of underwater sound propagation. Acoustic environmental changes and their effects on underwater sound propagation in the northern part of the East Sea, which have been poorly studied mainly due to lack of observations, are investigated by analyzing the hydrographic data acquired since 1993. Severe changes in acoustic environments are associated with various physical processes such as deep convection, thermal fronts, and eddies in the northern part of the East Sea. Spatio-temporal variations of sound speed field and the layer of the maximum sound speed are categorized into six typical cases. Using a sound source of 5 kHz, acoustic transmission losses are calculated range-independently for the six typical cases. Significant differences among the patterns of transmission loss in the six cases suggest that a different tactics are required when we operate in the northern part of the East Sea.

Study on Characteristics of Porcelain Insulators for High Strength with Alumina Composition (알루미나 조성에 따른 고강도 자기 애자의 특성 연구)

  • 조한구;한세원;박기호;최연규
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.3
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    • pp.353-359
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    • 2004
  • In this study. porcelain insulator samples which have a different alumina composition were manufactured in order to test electrical and mechanical properties and make an analysis of the propagation phenomena of micro cracks on porcelain body. From XRD quantitative analysis the crystalline phases were different with alumina composition, sample C and D which have about l7wt% Corundum phase without the Cristobalite phase shows better electrical and mechanical properties than sample A and B which have the Cristobalite phase. In dielectrics test on porcelain samples with below l7wt% alumina composition, it was found that the amount of glass phase(SiO$_2$) have an main effect to decrease the dielectric loss(tan$\delta$), and the dielectric breakdown voltage of aluminous porcelain insulators was largely affected by its relative density. As a micro tracks analysis, HRB were measured, then the intensity of HRB increased with the amount of alumina composition. On the other hand, the propagation behaviors of cracks was fairly influenced by the distribution of pores.

The Development of the Temperature Compensation Equipment to minimize Error in the Wireless Transmission System at 60GHz Band (60GHz대역 무선통신장애 해결을 위한 온도보상장치 개발)

  • Myung, Byung-Soo;Ku, Seong-Deag
    • Journal of the Korean Society of Industry Convergence
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    • v.8 no.2
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    • pp.97-104
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    • 2005
  • Usually, propagation attenuation of millimeter wave occurs by rainfall, snowfall, temperature, effect of pressure of air. In 60GHz wave band wireless communication network, temperature change becomes big factor of propagation loss department. Also, temperature change causes disturbance of 60GHz frequency at transceiver. In this study, we used 60GHz transceiver and found propagation loss of wireless path and operating frequency disturbance characteristics. In transceiver that there is no temperature compensated device, operating frequency of TX changed by 60.865GHz at temperature of $-5^{\circ}C$, and appeared by 60.730GHz when is $50^{\circ}C$. Therefore, operating frequency change width by temperature change are about 100MHz, greatly. But, in transceiver that there is temperature compensated device, operating frequency of TX changed by 60.830GHz at temperature of $-5^{\circ}C$, and appeared by 60.710GHz when is $50^{\circ}C$. Therefore, operating frequency change width by temperature change are about 20MHz. According to these result, we constructed between buildings examination wireless site for point to point wireless communication using 60GHz band transceivers who have do temperature compensated device, and investigated data transmission characteristics about ambient temperature change. Therefore, if use transceiver that have temperature compensated device, may overcome the wireless transmission error in 60GHz band wireless communication LAN networks despite of ambient temperature change.

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Effects of Drying Temperature on the Optical Properties of Solution Derived (Pb, La)$TiO_3$ Thin Films

  • Yoon, Dae-Sung;Kim, Sung-Wuk;Koo, Jun-Mo;Jiang, Zhong-Tao
    • The Korean Journal of Ceramics
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    • v.1 no.4
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    • pp.191-196
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    • 1995
  • Using sol-gel processing method, thin films of lathanum modified lead titanate(PLT) on Corning 7059 glass were prepared. A differential thermal analysis (DTA/TG) curve of gel powder and infrared spectra (FT-IR) of the films were measured to estimate residual organices in them. The heat-treated films were characterized by X-ray diffraction(XRD). Microstructures of the films were observed by a scanning electron microscope (SEM). Optical properties of the films were determined by a UV-VIS spectrophotometer. The waveguiding properties and optical attenuation were measured with the end coupling method and the cut back method. Effects of the drying conditions on the transmittance and the propagation loss of the films were investigated. Experimemtal results showed that the content of residual organics in the film decreased as the drying temperature of the film increased. As the La content of the film increased, the grain size decreased and the transmittance increased. The transmittances of the films increased with the increasing of the drying temperature. The propagation losses in the film decreased as the drying temperature increased.

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