• 한국통신학회논문지
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• 제17권5호
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• pp.460-471
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• 1992

본 논문에서는 최근에 주로 사용되는 디지털 PLL중 Tri-State 방식과 sample-Hold 방식을 사용한 PLL루프의 시간 불연속 동작을 묘사하기 위한 새로운 모델을 설정하여 비선형 PLL의 안정도 해석을 Z영역에서 하였으며 과도응답을 구하기 위한 상태방정식을 유도하였다. 종래에는 디지털 PLL의 시간 불연속 동작을 시간 연속 동작으로 근사화 시켜 선형적 해석을 하므로써 실제로는 시간 불연속 동작을 하는 디지털 PLL의 불안정한 영역을 정확히 찾아내지 못하였으나 새로운 모델에 의한 Z영역에서의 해석에서는 시간연속 해석에서 발견할 수 없었던 불안정 영역을 밝혀냄으로써 디지털 PLL의 최적 설계가 가능하도록 루프계수의 한계를 구하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2434-2453
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• 2019

To improve the separation performance of time-frequency overlapped radar and communication signals from a single channel, this paper proposes an effective separation method based on an improved empirical wavelet transform (EWT) that introduces a fast boundary detection mechanism. The fast boundary detection mechanism can be regarded as a process of searching, difference optimization, and continuity detection of the important local minima in the Fourier spectrum that enables determination of the sub-band boundary and thus allows multiple signal components to be distinguished. An orthogonal empirical wavelet filter bank that was designed for signal adaptive reconstruction is then used to separate the input time-frequency overlapped signals. The experimental results show that if two source components are completely overlapped within the time domain and the spectrum overlap ratio is less than 60%, the average separation performance is improved by approximately 32.3% when compared with the classic EWT; the proposed method also improves the suitability for multiple frequency shift keying (MFSK) and reduces the algorithm complexity.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.36-39
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• 2006

This paper examines critical successful facts related with the digital new product development with product innovation. For this, we have selected a Xcanvas time-machine TV of LG electronics and we have done case-study. We have performed in-depth interviews with engineers, team managers, marketers to get facts on the product development process and analyzed huge amount of data obtained from web-sites and related firms' materials. We have concluded that CSFs of Xcanvas time-machine TV are customer-centered product innovation, new perspective of considering technology and product, managing innovative team and motivation to team member.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 추계학술대회 논문
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• pp.107-112
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• 1996

In this paper it is proposed a new approach to the development of the automatic vision system to examine and repair the steam generator tubes at remote distance. In nuclear power plants workers are reluctant of works in steam generator because of the high radiation environment and limited working space. It is strongly recommended that the examination and maintenance works be done by an automatic system for the protection of the operator from the radiation exposure. Digital signal processors are used in implementing real time recognition and examination of steam generator tubes in the preposed vision system, Performance of proposed digital vision system is illustrated by experiment for similar steam generator model.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.109-109
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• 2000

In process industries, more than 90% of the control loops have PID controller. Futhermore, the most control systems are using classical PID controllers for their process control. Various auto-tuning methods of PID gains using relay-feedback are presented recently. In order to get the desired control performance, the correct tuning of PID controller is very important. This paper suggests how to tune of digital PID gains using information for both the Nyquist critical point by conventional method and another point by the relay feedback and hidden time-delay term. Simulation results show that the proposed controller has better performance than the conventional method.

• 한국정밀공학회지
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• 제17권8호
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• pp.94-99
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• 2000

In this study applied the general controller into th 16bit ordinary controller and recommand the simulator features the real system's propeties without DSP(Digital Signal Processing)-card. This simulator is designed to be synchronized in real time using A/D(Analog-Digital) convert and D/A(Digital-Analong) convert. In this study DSP card which is usually used for complex calculation is replaced with personal computer and designed to control, control-force using with the 16-bit micro processor.

• 디지털콘텐츠학회 논문지
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• 제6권3호
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• pp.189-193
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• 2005

최근 한국 대학은 급격한 구조조정이 이루어지고 있다. 한국 정부는 모든 4년제 대학교와 2년제 대학에 대해 대학평가를 실시하고 있다. 본 연구에서는 현재의 대학평가지수가 대학의 핵심성과지표(KPI: Key Performance Index) 로서의 의미를 갖는다고 보고 속도의 관점에서 대학평가지수를 분석하여, 대학 역시 의사결정의 속도가 중요함을 보이고 BI(Business Intelligence)시스템과 접목하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.140-143
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• 2001

Digital shearography, a speckle pattern method is based on the superposition of two laterally sheared images. Therefore, object points which are positioned in some distance from each other are superposed in the image plane. This shearography, one of NDT methods without contact, is able to inspect defects in pipelines and pressure vessels that are used in nuclear power plants. This is can inspect whole fields and has a low sensitivity to environmental noise. Because optical setting is very simple, it has a little exhaustion of time, cost and man power. And also it can find a defect position through real time monitoring of a part. This paper, finds out the relationship among shearing quantity image quality and defect size with this method.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권2호
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• pp.63-68
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• 1999

This pper describes a digital sensorless drive of permanent magnet brushless DC motors. In order to detect in real time the rotor positions of which Emf becomes zero, terminal voltages are sampled during PWM duty cycle. This method generates detection error in indirect sensed position, which is the harmonic component of PWM frequency. In this paper, the drive adopted Butterworth low pass filter for rejection of the sensing error and for accurate estimation of commutation time. Analytical design process of the digital filter is proposed and the experimental results show that the performance of the proposed sensorless drive is superior to that of the sensorless drives without filterint.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2004년도 정기총회 및 학술대회
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• pp.285-288
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• 2004

High-quality digital broadcasting contents are susceptible to illegal copy and unauthorized redistribution, which makes broadcasters difficult to protect valuable media assets. So, broadcasters and content providers need the technology for copyright protection of professional digital content. Digital watermarking technology is one of the most actively developed solutions for the copyright protection. This paper suggests the requirements of watermarking technology in DTV(Digital TV) environment for copyright protection and shows the developed real-time watermark embedding/detecting system for HD(High Definition)/SD(Standard Definition) video and experimental results of the system against watermark attack tests. Our watermarking system meets the watermarking requirements of invisibility, robustness and security of DTV environment.