• KIEE International Transactions on Power Engineering
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• v.4A no.3
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• pp.146-151
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• 2004

The most widely used primary protection for the internal fault detection of the power transformer is current ratio differential relaying (CRDR) with harmonic restraint. However, the second harmonic component could be decreased by magnetizing inrush when there have been changes to the material of the iron core or its design methodology. The higher the capacitance of the high voltage status and underground distribution, the more the differential current includes the second harmonic during the occurrence of an internal fault. Therefore, the conventional second harmonic restraint CRDR must be modified. This paper proposes a numerical algorithm for enhanced power transformer protection. This algorithm enables a clear distinction regarding internal faults as well as magnetizing inrush and steady state. It does this by analyzing the RMS fluctuation of terminal voltage, instantaneous value of the differential current, RMS changes, harmonic component analysis of differential current, and analysis of flux-differential slope characteristics. Based on the results of testing with WatATP99 simulation data, the proposed algorithm demonstrated more rapid and reliable performance.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.6
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• pp.593-598
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• 2014

Hand gesture recognition based on vision is a challenging task in human-robot interaction. The sign language of finger spelling alphabets has been tested as a kind of hand gesture. In this paper, we test hand gesture recognition by detecting the contour shape and orientation of hand with visual image. The method has three stages, the first stage of finding hand component separated from the background image, the second stage of extracting the contour feature over the hand component and the last stage of comparing the feature with the reference features in the database. Here, finger spelling alphabets are used to verify the performance of our system and our method shows good performance to discriminate finger alphabets.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.838-843
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• 1998

Risk importance measures are widely wed to rank risk contributors in risk-based applications. Typically, Fussell-Vesely (F-V) importance and risk achievement worth (RAW) are used in the component importance raking for the reliability centered maintenance (RCM) analysis of safety system in nuclear power plants (NPPs). This study was performed as part of feasibility study on RCM for domestic NPPs, which is focused on the component importance ranking approach the maintenance recommendation. The approach of modulizing faulting tree basic events was applied in the simplification process of the PSA model and the validity of the approach was evaluated As a result of the case study, this paper included the importance and the maintenance recommendations for the safety-related equipments associated with safety injection and containment spray in large loss of coolant accident sequences.

• Annual Conference of KIPS
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• 2000.10b
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• pp.1189-1192
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• 2000

CBSE(Component Based Software Engineering)은 소프트웨어 엔지니어링 세계에서 소프트웨어 개발 패러다임으로 바뀌고 있다. 이 영향은 전자상거래 소프트웨어의 개발에도 미치고 있다. 본 논문의 전자 상거래 전문 검색 시스템은 이전의 IHWA(Information Harvest WArehouse)검색엔진을 기초로 한다. 본 논문에서 CBSD에 입각해 IHWA기반의 사용자 훈련가능한 전자 상거래 검색 시스템의 새롭게 수정된 컴포넌트 구조를 소개한다. 전체 시스템 구조는 UML을 사용해 모델링 되었다.

• Journal of Communications and Networks
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• v.4 no.3
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• pp.209-220
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• 2002

In this paper, we propose a hierarchical packet scheduling technique to closely approximate a hierarchical extension of the generalized processor sharing model, Hierarchical Generalized Processor Sharing (H-GPS). Our approach is to undertake the tasks of service guarantee and hierarchical link sharing in an independent manner so that each task best serves its own objective. The H-GPS model is decomposed into two separate service components: the guaranteed service component to consistently provide performance guarantees over the entire system, and the excess service component to fairly distribute spare bandwidth according to the hierarchical scheduling rule. For tight and harmonized integration of the two service components into a single packet scheduling algorithm, we introduce two novel concepts of distributed virtual time and service credit, and develop a packet version of H-GPS called Hierarchical Fair Queueing (HFQ). We demonstrate the layerindependent performance of the HFQ algorithm through simulation results.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.131-133
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• 1995

Inductive high-Tc superconducting fault current limiter using YBCO superconducting ring in the secondary part has many advantages in power networks. It is based on the superconducting to normal transition and this paper describes its operational characteristics and experimental results, especially focused on the harmonic component analysis and recovery time. We fabricated and tested it under various conditions for the analysis of transient fault characteristics. And for the analysis of harmonics we used FFT methods. The superconducting ring was quenched in 240Arms and fault current was effectively limited to the lower current level. In addition, it was fast recovered when the fault condition was removed and after fault the system had odd harmonics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1370-1375
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• 2001

Substructure coupling or component mode synthesis may be employed in the solution of dynamic problems for structure. The model is partitioned into several subdomains. and a generalized Craig-Bampton representation is derived. In this paper the mode sets(normal modes. constraint modes) have been employed for model reduction. A generalized model reduction procedure has been described. Those reduction methods which adapt constraint modes have been described in detail. As examples. a flexible structure and a 10 DOF damped system are analyzed. Comparison with a conventional reduction method based on a complete model has been made via eigenpairs and dynamic responses.

• Phonetics and Speech Sciences
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• v.10 no.4
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• pp.121-125
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• 2018

This paper describes procedures of changing and measuring voice quality in terms of jitter. Jitter synthesis method was applied to the TD-PSOLA analysis system of the Praat software. The jitter component is synthesized based on a Gaussian random noise model. The TD-PSOLA re-synthesize process is used to synthesize the modified voice with artificial jitter. Various vocal jitter parameters are used to measure the change in quality caused by artificial systematic jitter change. Synthetic vowels, natural vowels and short sentences are used to check the change in voice quality through the synthesizer model. The results shows that the suggested method is useful for voice quality control in a limited way and can be used to alter the jitter component of voice.

• Annual Conference of KIPS
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• 2010.11a
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• pp.1635-1637
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• 2010

Simulation tools help creating a low cost and efficient development of embedded system. SID is an open source simulator software that consists library of components for modelling hardware and software components. A component can be written in C/C++ and Tcl/Tk. Currently, the SID simulation toolkit only provides support for C++ and Tcl/Tk. Tcl/Tk is used to write GUI-based components. However, we have observed that Tcl/Tk components cause slow simulation response because Tcl/Tk is a script language. It is not proper for developing the cutting-edge products with rich graphics. Therefore, in this paper, we suggest Java to a new language for GUI components in SID by developing a bridge module for SID to interworking with Java components.

• Annual Conference of KIPS
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• 2007.05a
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• pp.1417-1420
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• 2007

OpenVG는 낮은 수준의 하드웨어 가속 기능과 이를 바탕으로 하는 2D 벡터 그래픽 렌더링 API를 제공함으로써 모바일 환경에서 높은 화질의 그래픽을 구현할 수 있다. 이러한 장점에도 불구하고 OpenVG 엔진을 이용한 실제 사용자 인터페이스(User Interface)의 구현은 쉬운 일이 아니다. 그 이유는 OpenVG API에서는 기존의 개발 환경에서 제공하는 기본적인 위젯 컴포넌트(Widget Component)를 제공하지 않기 때문이다. 본 논문에서는 OpenVG를 용이하게 사용하여 효율적인 UI 구현을 위한 위젯 컴포넌트 시스템을 제시하고자 한다. 우선 OpenVG 엔진을 기반으로 위젯 컴포넌트와 그들 사이의 계층 구조와 상관 관계를 설계하고, 시스템이 구동되는 방식을 기술한다.