• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.332-338
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• 2010

Annually, electrical fires caused by arcing phenomena in power system rapidly increase as the use of more electric appliances, but there is no established method for the prevention of the accidents. With this background, this paper dealt with the experimental results on a series arc detection technique and a device for air conditioners. Series arcing phenomena that is generated in incomplete connection of air conditioners was simulated, and the frequency spectrum was analyzed. The Fast Fourier Transform (FFT) of the arc pulse showed that the dominant frequency components exist in ranges of 190 kHz~250 kHz and 900 kHz~1.6 MHz. An arc detection circuit with low cut off frequency of 170 kHz to attenuate 60 Hz by 170 dB and a signal discriminator were designed. Also, an algorithm which separate series arc signal from unwanted noises produced by switching operation, inverter, and surge was proposed. Application experiment was carried out on several types of air-conditioners by using the arc generator specified in UL1699, and the results showed the over 99 % accuracy.

• Journal of the Korean Geotechnical Society
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• v.36 no.10
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• pp.41-56
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• 2020

For the rapid and accurate warning, the system requires not only the sufficient number of seismometers but also the appropriate detection technique of sensor data. Instead of installing new seismometers, on-board accelerometers of the train could be utilized as alternatives. However, the data from on-board accelerometers includes train vibrations and the response of embankment site by earthquake, which are different from earthquakes measured from the seismometer. This study suggests signal analysis technique to detect earthquake from the on-board accelerometer data. The virtual on-board accelerometer data including the response of embankment site, obtained from site response analysis method, has been constructed. The constructed data has been analyzed using short time Fourier transform (STFT) and wavelet transform (WT). STFT method provides better performance to detect long-period earthquake whereas WT method is more available to detect short-period earthquake.

• The Journal of the Korea Contents Association
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• v.8 no.5
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• pp.9-18
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• 2008

Web-services have originally been devised to share information as open services. In connection with it, hacking incidents have surged. Currently, Web-log analysis plays a crucial clue role in detecting Web-hacking. A growing number of cases are really related to perceiving and improving the weakness of Web-services based on Web-log analysis. Such as this, Web-log analysis plays a central role in finding out problems that Web has. Hence, Our research thesis suggests Web-DoS-hacking detective technique In the process of detecting such problems through SOM algorithm, the emergence frequency of BMU(Best Matching Unit) was studied, assuming the unit with the highest emergence frequency, as abnormal, and the problem- detection technique was recommended through the comparison of what's called BMU as input data.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.2
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• pp.122-129
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• 2006

Shearography is one of optical methods that has been applied to nondestructive testing (NDT) and strain/stress analysis. The technique has the merit of the directly measuring relative displacement, which is insensitive to environmental vibration disturbance. Previous studies about the method have emphasized on extending its application to new fields and lack insufficient research on effective parameters for qualitative and quantitative evaluation of defects. In this paper, the influence of shearing amount on the detection of an internal defect is investigated. In experiment, slender defects along longitudinal direction of pipeline are artificially designed and detection results according to the change of shearing amount are analyzed. Based on the investigation, we propose the technique for the determination of defect size and accurate source location.

• Korean Journal of Veterinary Research
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• v.40 no.1
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• pp.56-62
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• 2000

Pasteurella multocida is kind of commensal bacteria in the upper respiratory tract of pigs. It is classified toxigenic and nontoxigenic strains based on the production of dermonecrotic toxin. Toxigenic strain is most associated with atrophic rhinitis which brings great economical loss in swine industry. However, toxigenic and nontoxigenic strains do not differ by diagnostic biochemical reaction or morphology. One of recently developed techniques, PCR detects the toxigenic P multocida. Amplification of an 846-nucleotide fragment of toxA gene was developed. The fragment amplified by PCR was detected in P multocida type D not type A. The PCR amplification was as sensitive as it could detect 1 pg of P multocida DNA. We compared the result of the PCR with the enzyme linked immunosorbent assay (ELISA) in a test for 40 swine nasal swabs. All of these isolates were toxin negative based on the ELISA while 2 isolates were detected in the PCR technique. in addition to accuracy, as required for rapid detection from contaminated nasal swabs, toxigenic P multocida was recovered efficiently from contaminated culture without inhibition of the PCR. The results show that the PCR detection of toxigenic P multocida directly form nasal swabs are feasible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6C
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• pp.539-546
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• 2010

In next generation wireless communication systems based on OFDM, multiple-input multiple-output (MIMO) technique is adopted in order to achieve high data throughput with limited bandwidth. As one of MIMO techniques, spatial multiplexing scheme needs high performance data detection algorithm that can be performed with low computational complexity. In this paper, we propose an algorithm that can compute QRM-MLD with reduced complexity. Also, hybrid detection technique is proposed, which can reduce the complexity by selecting between MMSE and QRM-MLD according to the channel condition. The proposed algorithm provides the trade-off between performance and complexity. The computer simulations for downlink transmission in 3GPP LTE system show that less than 0.1dB performance degradation can be achieved at 0.1% BER with 59% reduction on computational complexity compared with the conventional QRM-MLD algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.577-583
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• 2011

Radar performance test is one of the major steps for radar system design. However, it is restricted by time and cost when radar performance tests are performed with opportunity targets. So various simulated target generators are developed and used to evaluate radar performance. To simulate the target's range, most of simulated target generators are developed with optical line or DRFM(Digital RF Memory) technique but there are many restrictions such as limit of range imitation and test scenario because of their original usage. In this paper, DDL(Digital Delay Line) module for development of simulated target generator is designed with precise range simulation and easily embodiment feature. And pulse recognition and delay gap detection technique are used to simulate the time delay without distortions. Developed DDL module performances are verified through their performance tests and test results are described in this paper.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.1
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• pp.8-11
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• 2012

Automated Vision Inspection (AVI) systems automatically detect any defect feature in a surface image. The performance of the system can be measured under a special circumstances such as ultimate defect detection. In this situation, the defect signal level is similar to noise level and it becomes hard to make a solid decision with AVI systems. In this paper, we propose an effective preprocessing technique to enhance SNR (Signal to Noise Ratio). The method is motivated by some principles of HVS (Human Visual System) and RLC (Run Length Coding) techniques is used for this purpose. The proposed preprocessing technique enhances SNR under ultimate defect conditions and improves overall performance of AVI system.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.9-15
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• 2009

This paper proposes a cancellation algorithm of impulse noise using a rank-order method. The proposed method is a fast and simple algorithm that is composed of two parts. The first part involves noise detection using a fuzzy technique, where an image is divided into RGB color channels. Then every pixel in each color channel is investigated and assigned a probability indicating its chances of being a noise pixel. At this time, the rank order method using a noise-detection mask is utilized for accurate noise detection. Thereafter, the second part involves noise-cancellation, where each noise-pixel value in an image is replaced in proportion to its fuzzy probability. Through the experiments, both the conventional and proposed methods were simulated and compared. As a result, it is shown that proposed method is able to detect noisy pixels more accurately, and produce resulting images with high PSNR values.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1029-1032
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• 2008

Nowadays, the necessity of the NDT technique for concrete structure has been increased due to maintenance of infra-structure. With this reason, NDT detecting technique has been considered as a effective maintenance method to prevent the rapid degradation of the infra-structure. In this study, to investigate the internal defect of concrete structure, ultrasonic detection device and radar equipment was applied then tested in laboratory and field. In the result of the experimental test, the internal cavity and steel arrangement can be detected and it was possible to adopt the ultrasonic detection method to the maintenance of concrete structure. And an algorithm for performing the maintenance procedure of concrete structure applying ultrasonic detection device and radar equipment was developed and suggested in this study.