• MALSORI
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• no.63
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• pp.125-137
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• 2007

Recently, many techniques have been proposed to improve the noise robustness for speaker verification. In this paper, we consider the feature recombination technique in multi-band approach. In the conventional feature recombination for speaker verification, to compute the likelihoods of speaker models or universal background model, whole feature components are used. This computation method is not effective in a view point of multi-band approach. To deal with non-effectiveness of the conventional feature recombination technique, we introduce a subband likelihood computation, and propose a modified feature recombination using subband likelihoods. In decision step of speaker verification system in noise environments, a few very low likelihood scores of a speaker model or universal background model cause speaker verification system to make wrong decision. To overcome this problem, a reliable feature selection method is proposed. The low likelihood scores of unreliable feature are substituted by likelihood scores of the adaptive noise model. In here, this adaptive noise model is estimated by maximum a posteriori adaptation technique using noise features directly obtained from noisy test speech. The proposed method using subband-based reliable feature selection obtains better performance than conventional feature recombination system. The error reduction rate is more than 31 % compared with the feature recombination-based speaker verification system.

• Fire Science and Engineering
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• v.23 no.4
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• pp.137-144
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• 2009

This paper was studied on the problem of field inspection tester of the photoelectric type smoke detector. The experiment objects were chosen 3 type's testers such as A type (incense), B type (dimethylpolysiloxane), C type (mixtures of hydrocarbon) which were used for performance checking of the photoelectric type smoke detector for the fire protection. The experimental methods were used reliability verification experiment, performance verification experiment and performance change of fire detector by smoke component. It was confirmed through the experiment that the testers had problems of smoke concentration condition and wind velocity condition and smoke component. Consequently, this paper verified that the field inspection testers of the photoelectric type smoke detector had problems in the inspection of fire protection.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1149-1149
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• 2006

The leakage characteristic is an important factor in power plant. However, most of power plant have efficiency problem which is occurred leaking between high pressure steam turbine axle and stator. The labyrinth seal which is used between the main turbine axle and stator in the power plant. Because it is able to be non-contact seal and it is minimize clearance to decrease the leakage. But its actual system is too huge to experiment. Therefore, most steam turbine seal performance tests were conducted by air similarity test. This paper described a test facility and program for air similarity test of high pressure steam turbine seal. A test facility has been designed and built to evaluate leakage verification of labyrinth seal. The test facility consist of air compressor, anti-swirl labyrinth seal for 1/3 air similarity model, pressure transducer, air flow measure system, instrumentation and auxiliary system. For evaluation of steam turbine seal performance, the air similarity test of labyrinth seal leakage verification was conducted and we compared experiment data and analysis result.

• The Journal of Korean Association of Computer Education
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• v.11 no.1
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• pp.97-107
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• 2008

The result verification that determines correctness for the work results calculated in each PC is one of the most important issues in PC grid environments. In this literature, voting-based and trust-based schemes have been mainly used to guarantee the correctness of work results. However, these schemes suffer from both waste of resource utilization and high computation delay because they can not effectively cope with dynamic computational environments. To overcome these shortcomings, we introduce the distribution information of PC resources based on credibility and availability into result verification phase. Using this information, we propose a new result verification scheme, which can determine the correctness of work results by each PC resources' credibility and cope with the dynamic changing environments by each PC resources' availability. To demonstrate the efficiency of our result verification scheme, we evaluate the performance of our scheme from the viewpoints of turnaround time and resource utilization, utilizing resource distribution information in the Korea@Home that is a representative PC grid system in domestic. We also compare the performance of our scheme with that of other ones.

• Journal of Korea Multimedia Society
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• v.11 no.1
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• pp.53-60
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• 2008

Fingerprint verification method based on minutiae has been widely used for its speed and size stemming from utilizing only a few data, but it is vulnerable to some errors caused by the false minutiae extractions. A number of suggestions have been made to correct these problems. However, because it is very difficult to avoid all the external factors, such as noises that occur when fingerprints are collected, and all the internal factors that occur during the process of them, there is a limit in minimizing errors by improving the whole process. On the other hand, a fingerprint verification method based on images yields fewer errors because it makes direct comparison between images not using minutiae. Image-based fingerprint verification method has its limitations in aligning images with accuracy. Therefore, this paper proposes a new methodology to improve the performance utilizing both image-based and minutiae-based verification methods effectively. As the result of experimenting with both images and minutiae, the false accept rate and the false reject rate have been improved from 2.7% to 0.8% and from 6.5% to 5.5%, respectively.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.2
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• pp.73-80
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• 2006

Fingerprint-based verification system has been used for a very long time. Because of their well-known uniqueness and immutability, fingerprint is one of the most widely used biometric features. However, fingerprint identification system has such a critical weakness that the performance of verification is reduced drastically for a poor input fingerprint. In this paper, an image enhancement algorithm using enhanced direction and enhanced binary and aiming image is used to mitigate the problem in the preprocessing. The goal of image enhancement is to estimate the quality of input fingerprint image and to improve the clarity of ridge and valley structures of input fingerprint image. Also, a ridge orientation extraction method using index table is proposed to improve the speed of verification. It is shown by the experiments that proposed fingerprint verification system improves the minutiae extraction accuracy and performance of verification.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.738-744
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• 2017

Recently, the installation of energy storage systems (ESSs) has increased in parallel with the extension of renewable energy resources. However, there has been no concrete analysis ofthe performance verification and economic evaluation of ESSs,which makes it difficult to perform aneffective installation and operation of an ESS. In particular, there are no international technical standards and guidelines on electric ESS for frequency regulation applications. Therefore, acomprehensive study on the power quality, impact on grid, extent of contribution, and cost benefit study of ESS are strongly being required. Under these backgrounds, this paper proposes a performance verification algorithm on ESS for frequency regulation application based on ananalysis of the AGC(Automatic Generation Control) performance verification method of PJM in USA. In addition,this paper proposes an economic evaluation algorithm on a 500 MW installation of ESS for frequency regulation applications using the account settlement of an expensive gas-fired generation plant and coal-fired power generation plant. From the simulation with real ESS operation data and 500 MW installation case, it wasconfirmed that the ESS showssuperior performance toany other conventional generators and provides anannual benefit of 500 MW ESS are between 345~429 billon won.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.145-154
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• 2016

In this paper, a pneumatic device for the deployment performance verification of canards deployed by inertia has been designed and the performance of the pneumatic device has been proven through analysis and tests. The pneumatic conveying process, orifice opening process and piston movement process of the pneumatic device were investigated by using numerical methods. The orifice diameter, pressure in a pressure tank and type of gas were regarded as the main design parameters of the pneumatic device. The error rate between analysis and test results under the same conditions was within 4 %. The accuracy of numerical methods used in this study were validated.

• Phonetics and Speech Sciences
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• v.1 no.4
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• pp.127-132
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• 2009

The feature vectors which are used in conventional speaker recognition (SR) systems may have many correlations between their neighbors. To improve the performance of the SR, many researchers adopted linear transformation method like principal component analysis (PCA). In general, the linear transformation of the feature vectors is based on concatenated form of the static features and their dynamic features. However, the linear transformation which based on both the static features and their dynamic features is more complex than that based on the static features alone due to the high order of the features. To overcome these problems, we propose an efficient method that applies linear transformation and temporal information of the features to reduce complexity and improve the performance in speaker verification (SV). The proposed method first performs a linear transformation by PCA coefficients. The delta parameters for temporal information are then obtained from the transformed features. The proposed method only requires 1/4 in the size of the covariance matrix compared with adding the static and their dynamic features for PCA coefficients. Also, the delta parameters are extracted from the linearly transformed features after the reduction of dimension in the static features. Compared with the PCA and conventional methods in terms of equal error rate (EER) in SV, the proposed method shows better performance while requiring less storage space and complexity.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.1
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• pp.11-15
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• 2019

Recently, the circuit-breaker rated voltage is getting higher as the transmission voltage increases. To increase the circuit-breaker rated voltage, a multi-break circuit-breaker which has two or more breakers in series is adopted. For multi-break circuit-breaker, a grading capacitor is used to mitigate the Transient Recovery Voltage(TRV) and control the voltage distribution across the individual interrupter units. However, all over the world, there are many failures such as mechanical damage, explosion due to insulation breakdown. Therefore, it is necessary to study the causes of failure and the new performance verification method. In this paper, we investigate the causes of dielectric breakdown of the grading capacitors in the KEPCO power system and propose the performance verification method.