• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.1-9
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• 2010

This paper summarizes an education and training system for the auto-reclosing of power transmission system using a real time digital simulator. The system is developed to understand the principle of reclosing and the sequence of automatic reclosing schemes, and practice the effects of reclosing actions to power system in real-time simulator. This study is concentrated into the following two parts. One is the development of real time education and training system of automatic reclosing schemes. For this, we use the RTDS(real time digital simulator) and the actual digital protective relay. The mathematical relay model of RTDS and the actual distance relay which is equipped automatic reclosing function are also used. The other is the user friendly interface between trainee and trainer. The various interface displays are used for user handing and result display. The conditions of automatic reclosing which is a number of reclosing, reclosing dead time, reset time, and so on, can be changed by the user interface panel. A number of scenario cases are reserved for the education and training. Through the test, we verified that the proposed system can be effectively used to accomplish the education and training of automatic reclosing.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.3
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• pp.149-156
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• 2000

This study presents an investigation of the changes that have occurred in the coastal ocean area of Kwangyang Bay located in the South Coastal region of Korea using remote sensing data based on Landsat Thematic Mapper (TM) multispectral digital data from 1988 and 1996. The coastal changes were detected using the digital histogram method and vector trace method. All the images were preprocessed, i.e. geometrically corrected, before the training set selection. when comparing the histograms of 7-band TM data, it was found that the band 5 image exhibited two critical Digital Number(DN) peaks, thereby indicating new coastal water and coastal land data. Based on this information, the coastal ocean area of the band 5 image was calculated using the vector tracing method supported by a CAD program. The result shows that the coastal ocean area decreased by about 5 % between 1988 to 1994. Accordingly, this gives a strong indication that the continuing land development will have a serious impact on the ecosystem of Kwangyang Bay.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.1
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• pp.46-52
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• 2009

This paper design QHA(quadrifilar helical antenna) to receive efficiently Satellite-Digital Multimedia Broadcasting video signal. It is designed as quadrifilar structure with phase variation $0^{\circ}C$, $90^{\circ}C$, $180^{\circ}C$, $270^{\circ}C$ to obtain circular polarization. Upper gap, turn number and height of QHA are varied to obtain optimization dimensions. Optimization dimensions are gap=2.2mm, turn number=0.9, height=42mm and input reflection coefficient is approximately -5.8dB. Designed QHA can be applied to Satellite-DMB terminal.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.3
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• pp.342-348
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• 2015

This paper presents a 1.9-GHz digital ${{\Delta}{\Sigma}}$ fractional-N PLL with a finite impulse response (FIR) filter embedded for noise suppression. The proposed digital implementation of FIR provides a simple method of increasing the number of taps without complicated calculation for gain matching. This work demonstrates 32 tap FIR filtering for the first time and successfully filtered the in-band phase noise generated from delta-sigma modulator (DSM). Design considerations are also addressed to find the optimum number of taps when the resolution of time-to-digital converter (TDC) is given. The PLL, fabricated in $0.11-{\mu}m$ CMOS, achieves a well-regulated in-band phase noise of less than -100 dBc/Hz for the entire range inside the bandwidth of 3 MHz. Compared with the conventional dual-modulus division, the proposed PLL shows an overall noise suppression of about 15dB both at in-band and out-of-band region.

• Journal of Information Science Theory and Practice
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• v.10 no.spc
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• pp.12-24
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• 2022

This study attempted to investigate changes in collaboration structure for each stage of national Research and Development (R&D) in the artificial intelligence (AI) field through analysis of a co-author network for papers written under national R&D projects. For this, author information was extracted from national R&D outcomes in AI from 2014 to 2019. For such R&D outcomes, NTIS (National Science & Technology Information Service) information from the KISTI (Korea Institute of Science and Technology Information) was utilized. In research collaboration in AI, power function structure, in which research efforts are led by some influential researchers, is found. In other words, less than 30 percent is linked to the largest cluster, and a segmented network pattern in which small groups are primarily developed is observed. This means a large research group with high connectivity and a small group are connected with each other, and a sporadic link is found. However, the largest cluster grew larger and denser over time, which means that as research became more intensified, new researchers joined a mainstream network, expanding a scope of collaboration. Such research intensification has expanded the scale of a collaborative researcher group and increased the number of large studies. Instead of maintaining conventional collaborative relationships, in addition, the number of new researchers has risen, forming new relationships over time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2303-2307
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• 2006

The round off noise properties of wave digital filters have known and desirable properties in respect to their realization with short coefficient wordlengths. This paper presents the optimal implementation of wave digital filters by employing multiprocessor archtectures in the sense of input sampling rate, the number of processors, and input-output delay. The implementation will be specified by complete circuit diagrams including control signals, and can be applied to an existing silicon complier for VLSI layout generation.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.44-48
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• 2002

This paper describes an adaptive signal processing of digital receiver with DDC(Digital Down Convertor), DDC is implemented by using NCO(Numerically Controlled Oscillator), digital low pass filter. for the passband sampling, we present the results of digital receiver simulation with DDC. We confirm that the low IP signal is converted to zero IF by DDC. DOA(Direction Of Arrival) estimation technique using MUSIC(Multiple SIgnal Classification) algorithm with high resolution is presented. We Cow that an accurate resolution of DOA depends on the input sampling number.

• Journal of information and communication convergence engineering
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• v.11 no.4
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• pp.282-287
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• 2013

A real-time digital holographic display is the core technology for the next-generation 3DTV. Holographic display requires a considerably large amount of calculation. If generating a large number of digital holograms is intended, the amount of calculation and the time required increase exponentially. This is a significant obstacle in a real-time hologram service. This paper proposes an algorithm that increases the speed of generating a Fresnel hologram by using a recursive addition operation covering the entire coordinate array of a digital hologram. The 3D object designed to calculate the digital hologram uses a depth-map image produced by computer graphics. The proposed algorithm is a technique that performs the computer-generated holography (CGH) operation with only recursive addition of all of the hologram's coordinates by analyzing the regularity between the 3D object and the digital hologram coordinates. The experimental results show that the proposed algorithm increases the operation speed by 70% over the technique using the conventional CGH equation and by more than 30% over the previously proposed recursive technique.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.52-53
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• 2017

Through the case study, we surveyed an applicability of digital fabrication in irregular-shaped building construction project. By digital fabrication, we mean is a precision manufacturing method has been used in aircraft, ship and car manufacturing industry. We collected construction-completed "LotteWorld Tower Podium" project data and analyzed its process in terms of construction quality andduration. The result shows that digital fabrication is considered a competitive technology that enabled to complete the project in seven months within 3mm surface curvature threshold. The digitalfabrication is expected to apply on a number of irregular-shaped building construction project.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.65-68
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• 2000

In this paper, as a compatible software radio transmission system, Digital-Radio conversion system which can directly change the digital signal generated by the logic circuit into radio signal is proposed. By the vector synthesis method, the digital signals can change directly into radio signal. If such a circuit is realized, RF circuit and an antenna can be composed by the simple one device, and the radio is directly controlled and performed by the software processing which is the essence of software radio. This Digital-Radio conversion system of this paper give many number of communication channels being offered by PN code and offer a hardware design flexibility by digitization, therefore it decrease the percentage ratio of hardware of system and give a more flexible function of software basis. In this paper, this proposed Digital-Radio conversion system is called D/R converter, and the principle of this D/R converter, radio signal generation algorithm is explained and the performance characteristics of proposed algorithm is shown in time base by the computer simulation method.