• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.10
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• pp.947-952
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• 2006

It has been confirmed that the inner defect of insulator and the perfect diagnosis for aging are closely related to safe electric power transmission system and that the detection of accident and diagnosis technique turn out to be very important issues. But perfect diagnosis is difficult because discharge pattern is irregular. Thus, we investigated discharge pattern using the new distribution statistical models with cross-inked polyethylene(XLPE) specimens. Voltage was applied to power frequency by step method, and calibration of discharge was set to 50 pC. After the voltage was applied, it measured the discharge occurring during 10s. We investigated discharge pattern using the K-means analysis and Weibull function. We also investigated variation of centroid and shape parameter due to variation of voltage. As a result of analyzing K-means, it was confirmed that cluster including many object numbers was formed by the presence of void. And result of Weibull distribution, it was confirmed that shape parameter of discharge varied from 1.28 to 1.62 in no void specimens, and that shape parameter of discharge number varied from 1.28 to 1.62. In the void, shape parameter of discharge varied from 5.66 to 6.43, and shape parameter of discharge number varied from 5.05 to 5.08.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.56-62
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• 2013

We present a rectifier for wireless power transmission using multiplier configuration in layout for MOSFETs which works at 13.56 MHz, designed to fit in CMOS process where conventionally used diodes are replaced with the cross-coupled MOSFETs. Full bridge rectifier structure without comparators is employed to reduce current consumption and to be working up to higher frequency. Multiplier configuration designed in layout reduces time delay originated from parasitic series resistance and shunt capacitance at each finger due to long connecting layout, leading to fast transition from on-state to off-state cross-coupled circuit structure and vice versa. The power conversion efficiency is significantly increased due to this fast transition time. The rectifier is fabricated in $0.11{\mu}m$ CMOS process, RF to DC power conversion efficiency is measured as 86.4% at the peak, and this good efficiency is maintained up to 600 MHz, which is, to our best knowledge, the highest frequency based on cross-coupled configuration.

• Journal of the Korea Computer Graphics Society
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• v.23 no.1
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• pp.39-48
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• 2017

We present penetration depth (PD) computation algorithms using explicit Minkowski sum construction ($PD_e$) and implicit Minkowski sum construction ($PD_i$). Minkowski sum construction is the most time consuming part in fast PD computation. In order to address this issue, we find a candidate solution using a centroid difference and motion coherence. Then, $PD_e$ constructs or updates partial Minkowski sum around the candidate solution. In contrast, $PD_i$ constructs only a tangent plane to the Minkowski sums iteratively. In practice, our algorithms can compute PD for complicated models consisting of thousands of triangles in a few milli-seconds. We also discuss the benefits of using different construction of Minkowski sums in the context of PD.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.3
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• pp.344-352
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• 2002

In the analysis of the 3 dimensional plate structures by the finite element method, the triangular elements are generally used for the global stiffness matrix of the analyzed system. But the triangular elements of the plates have some problems in the process of formulation and in the precision of analysis. The formulation of the finite element method to analyze 3 dimensional plate structures using quadrilateral elements is presented in this paper. The degree of freedom off nodal point is 6, that is, the displacements in the direction off-y-z is and the rotations about x-y-z axis and then the degree of freedom off element is 24. For the comparison of the analysis using triangular elements and quadrilateral elements, the rectangular plates subjected to the uniform load and a concentrated load on the centroid of the plate, for which the theoretical solutions have been obtained, are analyzed. The calculated deflections of the rectangular plates using the finite element method by the triangular elements and the quadrilateral elements are also compared with the deflections of the plates calculated by theoretical solutions. The defections of the rectangular plates calculated by the finite element method using the quadrilateral elements are closer to the theoretical solutions than the defections calculated by the finite element method using the triangular elements. The deflection of the centroid of plate, calculated by the finite element method, converges to that of theoretical solution as the number of elements is increased. This convergence is much more rapid for the case of using the quakrilateral elements than fir the case of using triangular elements.

• Journal of Environmental Impact Assessment
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• v.18 no.3
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• pp.171-183
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• 2009

This study aims to analyze the sedimentary environment change in mid-channel bar of the lower Geum river basin after the construction of the estuary barrage using multi-temporal satellite data and GIS. The sedimentary environment changes were observed in mid-channel bar areas. The mid-channel bar F was found to have been newly formed for 10 years(1996-2006), whereas the mid-channel bar B located between mid-channel bar A and C has disappeared by erosion during the same periods. When examined by section, the areas of the mid-channel bar in the upper stream section from the Yipo's reference point generally increased due to the prevailing sedimentary environments, and those of the downstream section decreased where corrosive environments are dominant. In ternms of the centroid movement, the mid-channel bars grew up toward the downstream by switching erosion and accumulation, as sedimentation was prevailing in the downstream area of mid-channel bars and corrosion was dominant in the upper stream. Through grain size analysis, the study areas are divided into three sections according to the average grain size. In Section I, the mid-channel bars were formed as a result of sedimentary process of tides in the past. In Section II, the mid-channel bars were formed partly through the sedimentary process of rivers although the sedimentary process of tides is prevailing. In Section III, the mid-channel bars were formed mainly through the sedimentary process of rivers, even if it showed the sedimentary process of tides in the past.

• Proceedings of KOSOMES biannual meeting
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• 2006.05a
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• pp.59-64
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• 2006

In this study, the risk of SRRs was assessed upon the scale of the damage of marine accidents. For the risk assessment, inner-outer dependence methods and special knowledge-based fuzzy logic were introduced. Also, in order to calculate the importance of assessment value in this study, a max min composition method was used for fuzzy logic based on the principle of fuzzy extension and the centroid of gravity method was used for non-fuzzy formation. In order to produce the importance of assessment items, the inner-outer dependence methods were used for assessment items, and markov analysis method was used for the importance of the final comprehensive assessment. As a result, the risk of SRR of Tongyoung and Yeosu was proven relatively higher, thus, it needs to have more rescue ships and rescue devices for relieving the risk in the future.

• Proceedings of KOSOMES biannual meeting
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• 2004.05b
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• pp.1-6
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• 2004

This paper suggests an evaluation of risk level for damage of marine accidents in SRRs. Qualitative analyses in words is sometimes priorior to quantative analyses in numeric symbols. This paper intoduces a concept of fuzzy theory with the plenty of related literature review and AHP in the Korean SRRs of RCC and RSC. The methodology of this paper is max . min composition of fuzzy extensive principle, defuzzifiation is centroid of gravity methods. At the result, the evaluation of risk level is especially over Serious for smarine accident of Taean, Gunsan, Mokpo, Yosu, Tongyoung, Busan SRR. This paper recommends that many Rescue Vessels and Equipments need to the reduction of risk level about those.

• Journal of the Korean Society for information Management
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• v.18 no.3
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• pp.159-178
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• 2001

This paper presents an automatic text summarization model which selects representative sentences from sentence clusters to create a summary. Summary generation experiments were performed on two sets of test documents after learning the optimum environment from a training set. Centroid clustering method turned out to be the most effective in clustering sentences, and sentence weight was found more effective than the similarity value between sentence and cluster centroid vectors in selecting a representative sentence from each cluster. The result of experiments also proves that inverse sentence weight as well as title word weight for terms and location weight for sentences are effective in improving the performance of summarization.

• Journal of Navigation and Port Research
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• v.28 no.10 s.96
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• pp.909-915
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• 2004

This paper suggests an evaluation of risk level for damage of marine accidents in SRRs. Qualitative analyses in words is sometimes priorior to quantative analyses in numeric symbols. This paper introduces a concept of fuzzy theory with the plenty of related literature riview and AHP in the Korean SRRs of RCC and RSC. The methodology of this paper is $max{\cdot}min$ composition of fuzzy extensive principle, defuzzifiation is centroid of gravity methods. At the result, the evaluation of risk level is especially over Serious for marine accident of Busan SRRs. This paper recommends that many Rescue Vessels and Equipments need to the reduction of risk level about those.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.6
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• pp.271-278
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• 2004

In this paper, we propose a content-based audio genre classification algorithm that automatically classifies the query audio into five genres such as Classic, Hiphop, Jazz, Rock, Speech using digital sign processing approach. From the 20 seconds query audio file, the audio signal is segmented into 23ms frame with non-overlapped hamming window and 54 dimensional feature vectors, including Spectral Centroid, Rolloff, Flux, LPC, MFCC, is extracted from each query audio. For the classification algorithm, k-NN, Gaussian, GMM classifier is used. In order to choose optimum features from the 54 dimension feature vectors, SFS(Sequential Forward Selection) method is applied to draw 10 dimension optimum features and these are used for the genre classification algorithm. From the experimental result, we can verify the superior performance of the proposed method that provides near 90% success rate for the genre classification which means 10%∼20% improvements over the previous methods. For the case of actual user system environment, feature vector is extracted from the random interval of the query audio and it shows overall 80% success rate except extreme cases of beginning and ending portion of the query audio file.