• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.667-672
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• 2013

In this paper, we propose a multi-impedance changes localization method of on-voltage underground power cable using the wavelet transform based time-frequency domain reflectometry (WTFDR). To localize the impedance change in on-voltage power cable, the TFDR is the most suitable among reflectometries because the inductive coupler is used to inject the reference signal to the live cable. At this time, the actual on-voltage power cable has multi-impedance changes such as the automatic section switches and the auto load transfer switches. However, when the multi-impedance changes are generated in the close range, the conventional TFDR has the cross term interference problem because of the nonlinear characteristics of the Wigner-Ville distribution. To solve the problem, the wavelet transform (WT) is used because it has the linearity. That is, using WTFDR, the cross term interference is not generated in multi-impedance changes due to the linearity of the WT. To confirm the effectiveness and accuracy of the proposed method, the actual experiments are carried out for the on-voltage underground power cable.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.739-742
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• 2007

In the step processing multimedia information signals transmitted by a variety of mediums, noises are generated by the internal or exterior causes of systems and these noises degrade the perception about information signals. Therefore, in order to remove noises and restore signals a great number of researches have been progressed and recently, many noise removal methods using time-frequency localization of wavelet have been applied in wide applications. Moreover, when two wavelet bases are designed to accomplish the Hilbert transform pair, wavelet can be efficiently applied to detect characteristics of signals. Therefore, in this paper, in order to restore the corrupted signal by noises, a noise removal algorithm using the Hilbert transform pair of wavelet was proposed.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1282-1284
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• 1998

ZnO Varistor is an electronic ceramic device for controlling the surge voltage from low level to high. In this study, the puncture mechanism occurring in ZnO varistor is investigated, and the simulation for restraining the puncture by formulating the relation between the applied voltage and the increase of the inside temperature of grain is applied. In order to simulate the cause of the current localization which is the primary factor causing the puncture, the localization phenomenon and the temperature distribution induced by the localized current, the Voronoi network is applied, which can realize the structure of the practical varistor better than the established simple network. Using the current through each grain and the voltage applied to the grain boundary obtained from that simulation, the Joule heating energy is calculated and the phenomenon that the puncture occurs can be analyzed quantitatively by simulating the electric and thermal characteristics according to the externally applied pulsed voltage.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5522-5540
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• 2018

Vehicular license plate (LP) recognition system has risen as a significant field of research recently because various explorations are currently being conducted by the researchers to cope with the challenges of LPs which include different illumination and angular situations. This research focused on restricted conditions such as using image of only one vehicle, stationary background, no angular adjustment of the skewed images. A real time vehicular LP recognition scheme is proposed for the skewed images for detection, segmentation and recognition of LP. In this research, a polar co-ordinate transformation procedure is implemented to adjust the skewed vehicular images. Besides that, window scanning procedure is utilized for the candidate localization that is based on the texture characteristics of the image. Then, connected component analysis (CCA) is implemented to the binary image for character segmentation where the pixels get connected in an eight-point neighbourhood process. Finally, optical character recognition is implemented for the recognition of the characters. For measuring the performance of this experiment, 300 skewed images of different illumination conditions with various tilt angles have been tested. The results show that proposed method able to achieve accuracy of 96.3% in localizing, 95.4% in segmenting and 94.2% in recognizing the LPs with an average localization time of 0.52s.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.22-22
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• 2003

Studies on the optical properties related to the built-in internal field and the carrier localization present in various GaN-based structures are essential not only for the physical interest but in designing practical visible and ultraviolet light emitting device applications with better performance and quantum efficiency. We report on the optical characteristics of various dimensional GaN-based structures such as (i) GaN self-assembled quantum dots grown in Stranski-Krastanov mode (OD), vertically-aligned GaN nanorods (1D), graded-In-content InGaN quantum wells (2D), laterally-overgrown GaN pyramids (3D), and GaN epilayers grown on various substrates. We used a wide variety of optical techniques, such as photoluminescence (PL), PL excitation, micro-PL, cathodoluminescence, optically-pumped stimulated emission, and time-resolved PL spectroscopy. An overview and comparison of the optical characteristics of the above GaN-based structures will be given.

• Journal of Families and Better Life
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• v.26 no.5
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• pp.279-298
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• 2008

The purpose of this study is to review the trend in international marriage of Koreans based on Census data from 2001 to 2007 and to analyse socio-demographic characteristics of the married couples. This study remarks that as the primary causes underlying the recent increase in international marriages of Koreans, the change of worldwide condition such as globalization and localization, the condition of countries to leave immigrants, the change of sex/age ratio in population, and the change of value systems are addressed. Census data from the marriage and divorce registration for the period 2001-2007 are analysed. This study covers analysis of foreign partners' nationalities, remarriage, age gap between partners, education levels, male partners' occupation, region of residence and divorce in international marriage of Koreans.

• Journal of the Korean Institute of Rural Architecture
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• v.3 no.3
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• pp.11-21
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• 2001

This study is intended to clarify the ideologies and principles applied to the formative expression of church architecture which is contained both the God and human. From the result of study of modern architectural movement, all of architectural ideology have not been developed with the church architecture. Some of architectural concept have been the foundation of modern church architecture. From the point of view of theological aspects of Christianism, in church architecture which is hard to overcome the adherence of historical characteristics, especially nationalism which contain all the concepts and try the localization of church architecture play multi-functional roles to form expressional characteristics of the modern church architecture show harmonize to the modern architecture trend. The study is intended to clarify the nationalism-church architecture and to know the capability of our cases.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.29-38
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• 2024

The Matched Field Processing (MFP) is an estimation method for a source range and depth based on the prediction of sound propagation. However, as the frequency increases, the prediction inaccuracy of sound propagation increases, making it difficult to estimate the source position. Recently proposed, the Frequency-Difference Matched Field Processing (FD-MFP) is known to be robust even if there is a mismatch by applying a frequency-difference autoproduct extracted from the auto-correlation of a high frequency signal. In this paper, in order to evaluate the performance of the FD-MFP using a horizontal line array, simulations were conducted in the environment of the East Sea of Korea. In the area of Bottom Bounce (BB) and Convergence Zone (CZ) where detection of a sound source is possible at a long range, and the results of localization were analyzed. According to the the FD-MFP simulations of horizontal line array, the accuracy of localization is similar or degraded compared to the conventional MFP due to diffracted field and mismatch of sound speed. There was no clear result from the simulations conforming that the FD-MFP was more robust to mismatch than the conventional MFP.

• Journal of Navigation and Port Research
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• v.30 no.10 s.116
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• pp.801-808
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• 2006

To create the value-added in the field of the shipbuilding, we have to vitalize the marine equipment industry. However the competitiveness is inclined to its outward than inward in the field of the shipbuilding in our country. Especially the field of the marine equipment industry needs to acquire the competitiveness as soon as possible in comparison with an advanced country. Therefore, this paper analyzes the characteristics of the marine equipment, the present situation of the marine equipment industry, the present situation of the demand-supply, the localization of the marine equipment, so that it can raise the competitiveness of the marine equipment industry. Based on this paper, it is the purpose of this paper to derive the alternative for acquiring the competitiveness. This paper is trying to find the way to progress the marine equipment industry and suggest well-founded data for acquiring the competitiveness.

• Korean Journal of Biological Psychiatry
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• v.22 no.2
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• pp.87-94
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• 2015

Objectives The power spectral analysis of electroencephalogram has been widely used to reveal the pathophysiology of the alcoholic brain. However, the results were not consistent and the three dimensional study can be hardly found. The purpose of this study was to investigate characteristics of the three dimensional electroencephalographic (EEG) activity of alcohol dependent patients using standardized low resolution electromagnetic tomography (sLORETA). Methods The participants consisted of 30 alcohol dependent patients and 30 normal healthy controls. All the participants were males who had refrained from alcohol at least one month and were not taking any medications. Thirty two channel EEG data was collected in the resting state with eyes-closed condition during 30 seconds. The three dimensional data was compared between two groups using sLORETA for delta, theta, alpha, beta1, beta2, and beta3 frequency bands. Results sLORETA revealed significantly increased brain cortical activity in alpha, beta1, beta2, and beta3 bands each in alcohol dependent patients compared to normal controls. The voxels showing the maximum significance were in the left transverse temporal gyrus, left superior temporal gyrus, left anterior cingulate, and left fusiform gyrus in alpha, beta1, beta2, and beta3 bands respectively. Conclusions These results suggest that chronic alcohol intake may cause neurophysiological changes in cerebral activity. Therefore, the measuring of EEG can be helpful in understanding the pathophysiology of cognitive impairements in alcohol dependence.