• Journal of international Conference on Electrical Machines and Systems
• /
• v.3 no.4
• /
• pp.389-393
• /
• 2014

This paper presents one of the methods for design to reduce the noise and vibration of 200kW motor for electric propulsion ship. One of the important factors affecting vibration of the motor is the resonance. The natural frequency and natural mode of the 200kW motor is analyzed by using FEM tool and impact test equipment to avoid the resonance. Also, compare FEM result with impact test result to make a reliable FE model of 200kW motor. In order to find out the effect of the noise and vibration of the motor by electromagnetic excitation force, conduct electromagnetic-structure coupled analysis. These characteristics are much useful to design 200kW motor for electric propulsion ship.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.11
• /
• pp.748-751
• /
• 2015

Sound Masking System technology as by sound the same on all bands and artificially generates a constant sound shield People want to hear or recognize the people with the noise generated from the interior of the way. Prevent hearing or prevent recognition by using the technology to control the audible frequency band Continue to emit constant and uniform shielding sound audible frequency band Even the security content of speech (20 Hz~20 KHz). That interception laser eavesdropping, internal solicitations, during recording Or delay the decoding was a result of the effect of interference calculated Experience noise disturbance index is applied around the Stress Index is the average index is 10.16 was a luxury for the average index is then applied to the index 3.07 Noise is significantly lower stress level has improved noise conditions.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.5
• /
• pp.1001-1004
• /
• 2010

Acoustic feedback and background noise variation can degrade the performance of an active noise control (ANC) system. In this paper, nonlinear ANC using a non-parametric VSS-NLMS (or NPVSS-NLMS) algorithm and online feedback path modeling is proposed, whereby the conventional linear ANC with online acoustic feedback-path modeling is further extended to nonlinear Volterra ANC with a linear acoustic feedback path. In particular, the step-size of the NPVSS-NLMS algorithm is controlled to reduce the effect of background noise variation in the ANC system. Simulation results demonstrate that the proposed approach yields better nonlinear ANC performance compared with the conventional nonlinear ANC method.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.49 no.11
• /
• pp.610-616
• /
• 2000

This paper presents an active noise control algorithm via Walsh transform domain controller learned by genetic algorithm. Typical active noise control algorithms such as the filtered-x lms algorithm are based on the gradient algorithm. Gradient algorithm have two major problems; local minima and eigenvalue ratio. To solve these problems, we propose a combined algorithm which consist of genetic learning algorithm and discrete Walsh transform called Walsh Transform Domain Genetic Algorithm(WTDGA). Analyses and computer simulations on the effect of Walsh transform to the genetic algorithm are performed. The results show that WTDGA increase convergence speed and reduce steady state errors.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.11
• /
• pp.5382-5403
• /
• 2018

In this paper, for a spectrum sensing purpose, we heuristically established a test statistic (TS) from a sample covariance matrix (SCM) for multiple antennas based cognitive radio. The TS is formulated as a scaled-energy which is calculated as a sum of scaled diagonal entries of a SCM; each of the diagonal entries of a SCM scaled by corresponding row's Euclidean norm. On the top of that, by combining theoretical results together with simulation observations, we have approximated a decision threshold of the TS which does not need prior knowledge of noise power and primary user signal. Furthermore, simulation results - which are obtained in a fading environment and in a spatially correlating channel model - show that the proposed method stands effect of noise power mismatch (non-uniform noise power) and has significant performance improvement compared with state-of-the-art test statistics.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1254-1258
• /
• 2003

One of the major factors that effect sensor performance is analog noise that added in a sensor signal such as voltage. In multi-axis force sensors, error sources may be classified mainly in two groups. One is structural error due to inaccuracy of sensor body. The other error source is noise signals existing in the sensed information. This paper presents a brief review about the principle of multi-axis force sensors, and then proposes a method that can reduce the effect of noise signal to sensor performance. The method is to convert analog voltage signal to digital numbers near sensor body and then to read these digital signals and conduct signal processing in the computer. By this way, we can eliminate a bad effect of electromagnetic wave emitted from computer and of 60 Hz noise emitted from AC source. The proposed method is investigated through experimental demonstration. The experimental results show that it improves S/N ratio of the sensor about 40 times in our experimental setup.

• Proceedings of the KIEE Conference
• /
• 2004.04a
• /
• pp.192-195
• /
• 2004

Into investment expense that wind generation system that is one of clean energy is less than existent energy in narrow shipfitter maximum effect to source of energy that have Eoteulsu evaluate. There is shortcoming that Blade structure of existent aerogenerator faces at problem of safety accident in overpopulated area and noise and have additional expense of supply of electric power equipment. In this paper, We wish to supplement problem that is such through design of special Blade structure that have noise reduction and stability. Wish to achieve design and simulation of blade to use CATIA for this, and analyze adaptedness of system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.155-159
• /
• 2004

In this paper, it was analyzed the characteristics of electrical and acoustical variations for loudspeaker due to fabrication processes. First, mass of each components of loudspeaker was measured by electric precision scale and performed statistical analysis. Second. Thiele-Small parameters of sample loudspeakers produced by unskilled students were identified by known mass parameter identification method using electrical impedance method and investigated on the variations of each parameter. Electrical impedance tests and acoustic frequency responses were measured on sample loudspeakers and variations were examined to grasp relationship between components variation and fabrication processes. Main factors to effect the changes of electrical impedance were concluded by fabrication processes errors not by components of loudspeaker.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.7
• /
• pp.346-352
• /
• 2006

In Brushless DC Motor, there are Permanent Magnets (PMs) with driving circuit and sensor for detecting to rotor position and rotation speed. In the case of using hall IC sensor which response to magnetic flux, that is required to additional sensor magnet for rotor position detecting. Most of BLDC motor, However, take asymmetrical overhang of PM in rotor instead of additional sensor magnet for operating of hall IC sensor. The asymmetrical overhang of PM occur rotor thrust to z-axis direction that is lead to not only damage of bearing but also intensive noise and vibration. Therefore, the analysis of magnet overhang effect in the side of vibration and drive to hall If sensor is required to precise. In this paper, 2-D Finite Element Method is used to solve precise field computation and thrust of z-axis direction considering asymmetrical magnet overhang. And also the z-axis thrust from the analysis result is compared to experimental result. In conclusion, the purpose of this paper minimize to noise and vibration of BLDC Motor as analyzes to asymmetrical magnet overhang effect.

• Journal of the Korean Society of Safety
• /
• v.17 no.1
• /
• pp.45-53
• /
• 2002

The purpose of this study was to investigate effect of electrical noise on malfunction of the earth leakage circuit breaker. A three-way experiment for studying its malfunction was conducted, in which electrical products such as radio, alternating current are welder and cellular phone, distance from the earth leakage breaker to electrical products, and whether or not the earth leakage breaker is contained is contained in the steel box were employed as experimental variables. Eleven earth leakage breakers frequently used in real situations were tested in each experimental treatment. The electrical products were used for generating electrical noise that is known to be able to cause malfunction of the earth leakage breaker. The results showed that except a case for one of the 11 earth leakage breakers when the radio made by M company was located 30 cm ahead of the breaker, malfunction did not occur in any other experimental treatment. Consequently, it is suggested that the breaker should be normally used for preventing electricity-related accidents without fear of its malfunction in industrial sites.