• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 춘계학술대회논문집
• /
• pp.587-592
• /
• 2005

Main transformer's integrity assessment in nuclear power plant is estimated by the electrical test of electrical core and wire and the chemical analysis of insulating oil. Mechanical test or analysis has not been so far. So this study makes it with the vibration velocity rating. The vibration velocity rating in main transformer which is based on the real data of vibration velocity measurement under operating and other machinery vibration code such as ISO code is renewed.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
• /
• pp.493-499
• /
• 1997

In this study, the changes in transmitting and receiving characteristics, especially resonance frequencies, of the underwater acoustic planar array transducer by the transformers used in the analog weighting circuit are investigated. Electrical equivalent circuit analysis shows that an ideal transformer does not change the resonance frequency of the transmitting mode, but the resonance frequency which gives the maximum receiving sensitivity can be designed by adjusting the magnitude of reactance of transformer.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제16권6호
• /
• pp.754-759
• /
• 2016

A transformer feedback low-noise amplifier (LNA) is implemented in a standard $0.18{\mu}m$ CMOS process, which exploits drain-to-gate transformer feedback technique for wideband input matching and operates across entire 3~5 GHz ultra-wideband (UWB). The proposed LNA achieves power gain above 9.5 dB, input return loss less than 15.0 dB, and noise figure below 4.8 dB, while consuming 8.1 mW from a 1.8-V supply. To the authors' knowledge, drain-to-gate transformer feedback for wideband input matching cascode LNA is the first adopted technique for UWB application.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
• /
• pp.38-42
• /
• 2001

This paper describes an application of the on line partial discharge measurement method in operating transformer. In the operating transformer, the partial discharge signal may be superimposed by radio intereference voltage(RIV) and pulse shaped noise signals generated by external corona. The partial discharge quantity showed about 3,800pC due to very high sinusoidal interferences at the measuring impedance terminal of the transformer bushing tap. In order to reject these noises, this paper applied RIV filter, band-pass filters and noise gating method. The resulting measuring sensitivity was improved from 3,800pC to 160pC.

• 한국소음진동공학회논문집
• /
• 제23권6호
• /
• pp.527-536
• /
• 2013

In order to predict structural vibration and radiated noise of high-voltage transformer in operation, it is necessary to precisely find the excitation force generated by the coils and core. However, finding the excitation force through experiments of high voltage transformer in operation is not possible. Therefore, this paper deals with identifying the excitation force by using the acceleration data measured through experiments and the transfer function estimated through finite element model. A method to predict structural vibration and radiated noise was also proposed. Three-phase windings and the core are the source of high-voltage transformer. The excitation forces were identified using the acceleration data and the transfer function of the surface of the tank. Structural vibration and radiated noise from the surface of the tank was predicted by using the identified excitation force. As a result of the interpretation of the experimental and computational analysis of structural vibration from the surface of the tank and radiated noise from the field point, the interpretation of the computational analysis showed relatively good accordance with the experiment.

• 한국소음진동공학회논문집
• /
• 제18권9호
• /
• pp.982-989
• /
• 2008

There is a noticeable hum from the inverter board of LCD TV when in operation. In this study, we investigate the source and the characteristics of this noise for the inverter board of LCD TV using measurement of vibration and noise. Modal analysis of vibration and noise is visualized for identification of noise sources and transmission vibration. The main source of noise was the transformer of the LCD TV inverter. A noise reduction was achieved by damping the structural elements.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 추계학술대회 논문집
• /
• pp.236-236
• /
• 2009

This paper demonstrates the application of the preventive maintenance, process to analyse and develop preventive maintenance tasks for rectifier and electric transformer in the SeoulMetro company. Attention is given to the frequency designation, technical details regarding the radiometer, previous electromagnetic noise measurements, and applications of the noise data. This study confirms the feasibility and effectiveness of preventive maintenance applications in the electric trains.

• 한국소음진동공학회논문집
• /
• 제12권6호
• /
• pp.413-419
• /
• 2002

Noise barriers are widely used to reduce the sound level propagating from highways, railways or factories to residential areas. The reduced noise level at a receiver point is then determined by the diffracted waves around the edge of the barrier as well as by the transmitted waves through the barrier. 1'or proper usage, many studies either theoretical or experimental have been made with the objective of precisely Predicting the acoustic field and improving the noise attenuating properties of barriers. In this study. a simple scattering model. a line acoustic source scattered by an infinite cylinder, is introduced to simply Investigate the sound attenuation efficiency of a sound-resonating barrier. From this model study, it is observed that the sound-resonating harrier can be used as a good sound-shielding element especially for the pure-tone noise generated from the transformer. Large sound-attenuation is achieved by applying the sound-resonating barrier to the large transformers in a substation.

• 전기학회논문지
• /
• 제56권9호
• /
• pp.1556-1560
• /
• 2007

Energized power transformers in substations make unwelcome noises which propagate to nearby residential areas. As the excessive noise level become a target of public grievance than ever, utilities are seeking solutions to it. This paper introduce a power transformer noise prediction program which can give utilities effective solutions. Once a noise source is given, the program calculates the propagated noise level at certain points. The estimated result is rendered as noise contour map. To validate the accuracy of the program, the predicted noises are compared to measured one in real substations and proven to be acceptable within a margin of 5 percent.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.659-664
• /
• 2001

Noise barriers are widely used to reduce the sound level propagating from highways, railways or factories to residential areas. The reduced noise level at a receiver point is then determined by the diffracted waves around the edge of the barrier as well as by the transmitted waves through the barrier. For proper usage, many studies either theoretical or experimental have been made with the objective of precisely predicting the acoustic field and improving the noise attenuating properties of barriers. In this study, a simple scattering model, a line acoustic source scattered by an infinite cylinder, is introduced to simply investigate the sound attenuation efficiency of a sound-resonating barrier. From this model study, it is observed that the sound-resonating barrier can be used as a good sound-shielding element especially for the pure-tone noise generated from the transformer. Large sound-attenuation is achieved by applying the sound-resonating barrier to the large transformers in a substation.