철도차량용 알루미늄 압출재의 투과손실

김석현,박정철,김종년 江原大學校 附設 環境硏究所 2000 環境硏究 Vol.17 No.-

Sound transmission characteristics are investigated on the aluminium extruded panels used for railway vehicles. An equivalent orthotropic plate model and mass law are applied to predict the sound transmission loss. An extruded panel specimen used in the floor of railway vehicles is manufactured and is tested to measure sound transmission loss by two reverberant chamber method. Predicted transmission loss is compared with measured values and the effect of local resonance on the transmission characteristics is identified. The results are applied to design the extruded panel having better sound insulation performance.

6kW 독립형 풍력발전기의 진동 모니터링 및 분석

김석현,남윤수,유능수,이정완,박무열,박해균,김태형 江原大學校 産業技術硏究所 2005 産業技術硏究 Vol.25 No.A

A vibration monitoring system for a small class of wind turbine (W/T) is established and operated. The monitoring system consists of monolithic integrated chip accelerometer for vibration monitoring, anemometers for wind data acquisition and auxiliary sensors for atmospheric data. Using the monitoring system, vibration response of a 6kW W/T generator is investigated. Acceleration data of the W/T tower under various operation condition is acquired in real time using LabVIEW and is remotely transferred from the test site to the laboratory in school by internet. Vibration state of the tower structure is diagnosed within the operating speed range. Resonance frequency range of the test model is investigated with the wind speed data of the test site.

철도차량용 주름판재의 차음성능

김석현,박정모 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.B

Sound insulation performance is investigated on the corrugated panel used for a rail way vehicle. Random incidence sound transmission loss is calculated by using the equivalent orthotropic plate model. Analysis results on several kinds of corrugated panels are in good agreement with the measured data. The analysis method is applied to predict the sound transmission loss of the corrugated panel used for Korean high speed train.

회의실내 유리창 진동의 도청에 대한 연구

김석현,김윤호,허욱 강원대학교 산업기술연구소 2007 産業技術硏究 Vol.27 No.A

Possibility of the eavesdropping is investigated on a conference room-glass window coupled system. Speech intelligibility analysis is performed on the eavesdropping sound of the glass window. Using MLS(Maximum Length Sequency) signal as a sound source, acceleration and velocity responses of the glass window are measured by accelerometer and laser doppler vibrometer. MTF(Modulation Transfer Function) is used to identify the speech transmission characteristics of the room and window system. STI(Speech Transmission Index) is calculated by using MTF and speech intelligibility of the vibration sound is estimated. Speech intelligibilities by the acceleration signal and the velocity signal are compared.

750kW 풍력발전기의 소음실증

김석현,허욱,이현우 江原大學校 産業技術硏究所 2007 産業技術硏究 Vol.27 No.B

This study introduces an environmental noise evaluation procedure and results for a wind turbine (W/T) system. Test and evaluation are required by the international standard IEC 61400-11 in the aspect of environmental effect. Test and evaluation are performed on U-50 WT model which is first developed by the domestic W/T manufacturer. W/T test model is under operation in Daekwanryung wind test site. An integrated monitoring system in the test site is utilized for the evaluation. With the noise signal, meteorological data and W/T operational data are monitored in real time by the integrated monitoring system using LabVIEW. From the measured noise data, acoustic power level are estimated and compared with those of other similar size WT under the wind speeds required by international standard.

춘천시민의 종의 진동 및 음향 특성

김석현,김태형,김윤호,한영호 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.A

The Chun-cheon Citizen's Bell was cast in memory of hosting the 2010 world leasure conference and a striking ceremony was held at the city hall on December 31, 2005. In this study, vibration and sound of the bell are measured and the property of the magnificent sound of the bell is scientifically investigated. Frequency components making the sound are identified and how the frequency components decrease with time is observed using waterfall plot(3-dimensional frequency spectrum). Beat characteristics of the hum(1st frequency) and the fundamental(2nd frequency)are examined by experiment. Directivity of the sound radiation of the bell is examined by measuring the vibration and sound in several directions. Duration of the vibration and the sound is estimated using damping ratio.

구리의 전기석출시 젤라틴이 물성에 미치는 영향

신석재,강현춘,안형환,강안수,김용렬,한성만,이한섭 明知大學校 産業技術硏究所 1995 産業技術硏究所論文集 Vol.14 No.-

In the electrodeposition of copper foil for preparing printed circuit boards, a little amount of gelatin as a addition agent has been used for the better characteristics of a coat of electroplating. Gelatin modifies the physical properties such as mechanical strength, matte-side roughness, ultimate tensile strength(U.T.S), and elongation of copper foil, furthermore gelatin have influence on the structure of electrodeposits and the cathode polarization. The electrolyte used was of a composition; CuSO₄·5H₂O 300g/ℓ, H₂SO₄ 100g/ℓ, NaCl 10 ppm as a brightner, and was gelatin 0-7 ppm as a addition agent. Current density was 50 A/dm², and the temperature of electrolytic bath was 50 to 52 ℃. Experiments showed that the optimum gelatin concentration was 5 ppm with the consideration of the numbers of electrodeposited nuclei. And the nuclei numbers was sharply increased under 5 ppm, but was almostly constant above 5ppm. Average matte-side roughness by Surfcorder was gradually increased with the increasing gelatine concentration up to 2 ppm, and maximum roughness was observed at 2ppm. The roughness showed gradual decrease within the concentration range of 2 to 4 ppm, and was almost constant above 4ppm . Within the gelatine concentration range of 0 to 7 ppm, as the concentration increased, UTS was increased and elongation was decreased logarithmically. Also, in comparison between UTS and elongation, gelatin was identified as an addition agent acting inversely.

케이블 지지된 풍력발전기 타워 구조 모델의 진동해석

김석현,박무열,최승훈 강원대학교 산업기술연구소 2007 産業技術硏究 Vol.27 No.A

A theoretical model based on Rayleigh-Ritz method is proposed to predict the resonance frequency of a W/T(Wind Turbine) tower structure supported by guy cables. In order to verify the validity of the theoretical model, a reduced W/T tower system is manufactured and tested. Frequency response and mode data are determined by modal testing and finite element analysis is performed to calculate the natural frequency of the tower model. Numerical and experimental results are compared with those by the theoretical analysis. Parametric study by the theoretical model shows how the cable tension and cable elasticity influence the resonance frequency of the W/T tower structure. Finally, vibration response under various rotating speed is investigated to examine the possibility of severe resonance.

1kW 소형 풍력발전기의 진동 성능 모니터링

김석현,남윤수,유능수,박무열,김태형,박해균 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.A

A vibration monitoring is performed on a 1kW class stand alone wind turbine(W/T). When a W/T model is developed, general performance under various wind condition should be verified to introduce the product in the market. Especially, vibration characteristics within operating speed range are very important in the aspect of structural stability as well as generator's electrical efficiency. This paper examines the vibration performance of a home made 1kW W/T. Various data of the W/T model are acquired in real time using a remote vibration monitoring system installed in Daekwanryung test site. Vibration stability of the W/T structure is diagnosed based upon the data and the result is used to estimate the applicability of the W/T model.

6kW 풍력발전기 타워-케이블계의 고유진동수 해석

김석현,박무열 江原大學校 産業技術硏究所 2009 産業技術硏究 Vol.29 No.A

Vibration characteristics of a 6kW stand alone W/T(wind turbine) system are experimentally and theoretically investigated. Vibration resonance of the tower-cable system is monitored and the data are analysed and compared with the analytical results. To predict the resonance speed of the cable supported W/T, Rayleigh-Ritz method is applied to the tower-guy cable coupled system. Parametric study on the relation of the cable tension, cable elasticity and resonance frequency is carried out. Results of the study are utilized to design the stable structure of small size wind turbines which consist of a pivoted tower and guy cables.