• Journal of KSNVE
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• v.6 no.6
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• pp.709-715
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• 1996

In recent years, the piping vibration in many Power Plants is being increased by the aged generating facilities due to a long time use. Generally, the pressure fluctuations associated with the flow-induced excitations in this case are broadband in nature. Mainly, the dominant sources of vibration are a vortex-shedding, plane waves and boundary layer turbulence. The peak level of the spectrum is proportional to the dynamic head. A severe disturbance in pipeline results in the generation of intense broadband internal sound waves which can propagate through the piping system. The characteristic frequencies of operating loads of 20%, 57%, 70%, 100% are 4 - 6 Hz and coincide with the results from impact hammering test and FEM analysis. We chose the wire energy absorbing rope restraint as a vibration reduction method after reviewing the various conditions such as site, installing space and economic cost etc. After installation, the vibration level was reduced about 54% in velocity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.659-664
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• 2008

In this study, it is outlined that heavy weight floor impact noise induced by the vibration of slab can be reduced by multi tuned mass damper(MTMD) effectively. Substructure synthesis is utilized to develope analytical model of slab coupled with MTMD and acoustic power is introduced to evaluate the performance of noise control for simplicity. Numerical analysis is carried out to investigate the effect of the properties of MTMD on the vibration and noise control. Numerical analysis shows that mass ratio of MTMD is critical on the vibration and noise control of the slab and it is essential to reduce the vibration in higher modes of slab because it has a great effect on the radiation of sound.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.491-495
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• 2008

The effects of vehicles and pavement surface types on noise have been investigated at the Korea Expressway Corporation's Test Road along the southbound side of the Jungbu Inland Expressway, South Korea. The study was conducted in 2005 and 2006 through field measurements at nine surface sections of asphalt concrete and Portland cement concrete pavements using eleven vehicles. For the road noise analysis, the sound power levels (PWLs) of combined noise (e.g., tire/pavement interaction noise and power-train noise together) and tire/pavement interaction noise using various vehicles were calculated based on the novel close proximity (NCPX) and pass-by methods. Then, the characteristics of the PWLs were evaluated according to surface type, vehicle type, and vehicle speed. The results show that the PWLs of vehicles are diversely affected by vehicle speed and the condition of the road surface.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.162-165
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• 1998

The non-thermal pasteurization of foods using High Voltage High Current Pulsed Electric Fields (HVHC-PEF) is a promising technology and a sound complement or replacement to traditional thermal pasteurization. The conventional thermal method also inactivates bacteria and other microorganisms harmful to humans, but degrades natural color, flavor, texture and nutrients. At this point, a nonthermal pasteurization technique, HVPEF is thought to be a new processing technique which is able to produce a good quality foods nutritional as well as sensuous. In this paper, the system for HVHC-PEF pasteurization is presented. It use square wave pulse instead of exponential ones. So, power rating of system is reduced considerably. Design considerations for 20kV 500A class equipment are analyzed and experimental results are discussed.

• Speech Sciences
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• v.9 no.4
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• pp.253-263
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• 2002

In this paper, we propose new algorithm of speaker recognition which identifies the speaker using the information obtained by the intensive speech feature analysis such as pitch, intensity, duration, and formant, which are crucial parameters of individual voice, for candidates of high percentage of wrong recognition in the existing speaker recognition algorithm. For testing the power of discrimination of individual parameter, DTW (Dynamic Time Warping) is used. We newly set the range of threshold which affects the power of discrimination in speech verification such that the candidates in the new range of threshold are finally discriminated in the next stage of sound parameter analysis. In the speaker verification test by using voice DB which consists of secret words of 25 males and 25 females of 8 kHz 16 bit, the algorithm we propose shows about 1% of performance improvement to the existing algorithm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.361-364
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• 2011

In this paper, This work demonstrates a experimental evaluation for vehicle road noise NVH performance from the component-level NVH measurements of Tire. The power unit noise from tire emitted by cars has been reduced. It has been found that tire noise dominates noise produced by the power train when vehicles are driven at high constant speed. Therefore tire pattern noise is affected by pattern and vehicle and transmission loss. Tire noise mechanism is generated by several mechanisms. The sound of tire can propagate either through the air or through the structure of vehicle. Pattern noise is the result of pressure variations through the air to the interior side of vehicle. Especially, smooth asphalt, the periodicity of tread design, groove depth is important factor, which have an influence on the reduction of tire pattern noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1142-1147
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• 2002

For the evaluation of the DC motor noise and vibration, usually it is rely on human feeling because some kinds of noise are not definitely represented by measurement Instrument such as sound meter. But when we consider time signal of the noise and vibration. It is possible to represent them. And in this paper. it is suggested to study output current shape of the motor because it Is the source to make speed and torque variation of the motor. If the current shape is not stable. it makes operating state of the motor unstable and produces noise and vibration. By analyzing signal at time and frequency of noise and vibration and current shape. it is possible to automation of the noise and vibration measurement in the Production line.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.340-343
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• 2006

As the needs of consumer on ride comforts increase and the reduction of road traffic noise tightened step by step, the power unit noise emitted by cars has been reduced. It has been found that tire noise dominates noise produced by the power-train when vehicles are driven at high speeds. Therefore, in these days, tire/pavement noise is concerned. Tire/pavement noise is affected by pavement type and vehicle???s transmission loss. Tire noise mechanism is produced by several mechanisms. The sound of tire can propagate either through the air or through the structure of vehicle. Pattern noise is the result of pressure variations through the air to the interior side of vehicle. Especially, on smooth asphalt the periodicity of tread design, pitch sequence is important factor, which have an influence on the reduction of tire noise.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.927-929
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• 1997

In this paper, a new expert system scheme, called Logic Based Expert System (LBES), is proposed for real time fault diagnosis of power system. In LBES, Expertise is represented by logical connectives and converted into a Boolean function. The set of Prime Implicants (PIs) of the Boolean function contains all the sound inference results which can be obtained from the expertise. Therefore, off-line inference is possible by off-line PI identification, which reduces the on-line inference time considerably and makes it possible to utilize-the LBES in real-time environment.

• Publications of The Korean Astronomical Society
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• v.28 no.2
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• pp.17-23
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• 2013

Song I-Yeong (1619 ~ 1692), who was an astronomy professor of Gwansanggam (觀象監, Bureau of Astronomy), created the Honcheonsigye (渾天時計, Armillary Clock) in 1669 (10th year of King Hyeonjong Era). Honcheonsigye was a unique astronomical clock which combined an armillary sphere, the traditional astronomical instrument of the Far East, with the power mechanism of western alarm clock. The clock part of this armillary clock is composed of two major parts which are the going-train, power unit used the weight, and the time signal system in a wooden case. The time signal system is composed of four parts which are the time-annunciator, the striking train, the 12 different time-announcing medallions and the sound bell. This clock has been neglected for many years and its several components have been lost. This study is to understand the structure of time signal system and suggests the restoration process.