• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.4
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• pp.55-60
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• 1983

A new type of digital phase-locked loop (DPLL) that employs a multilevel quantified timing error detector (TED) is proposed and analyzed under the assumption of negligible quantizing effect and no noise. Since the timing error is quantized uniformly, the TED has a linear characteristic. From the linear characteristic of TED, a first order difference equation describing the behavior of the loop is derived. Using the system equation, the loop is analyzed mathematically for phase step and frequency step input. Desired locking condition for the loop to be locked and the lock range for the DPLL's to achieve exact locking independently of initial conditions are ob-tained. And these analyses are confirmed by timing error plane plots and computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11A
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• pp.1848-1857
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• 2001

This paper proposes the ETEO and MTEO burst signal detector based on TEO algorithm. These algorithms must be used after STR and AGC operation, but are not related to phase and frequency offset. ETEO algorithm is extended version of original TEO, and MTEO algorithm is proposed for improving the output characteristics of ETEO. Also, modified ETEO and MTEO algorithm are proposed for detection of PREAMBLE64. Optimal threshold value is determined and miss and false alarm probability and FER performance are evaluated by computer simulation. Finally, this paper proposes MTEO algorithm with M=3 to guarantee the Performance that FER is less than 10$\^$-2/.

• Journal of Korea Water Resources Association
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• v.48 no.8
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• pp.613-623
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• 2015

To overcome the difficulties of discharge measurements during flood season, MWSCM(micowave water surface current meter) which measures river surface velocities without contacting water has been applied in field work since its development. The existing version of MWSCM is for floods so that its applicability is low due to the short periods of floods. Therefore the renovative redesign of MWSCM to increase the applicability was conducted so that it can be applied to the discharge measurements during normal flows as well as flood ones by extending the measurable range of velocity. A newly developed high-performance MWSCM for general use can measure the velocity range of 0.03-20.0 m/s from flood flows to normal flows, whereas MWSCM for floods can measure the velocity range of 0.5-10.0 m/s. The improvement of antenna isolation between transmitter and receiver to block the inflow of transmitted singals to receiver and the improvement of phase noise of oscillator are necessary for detecting low velocity with MWSCM technology. Separate type antenna of transmitting and receiving signals is developed for isolation enhancement and phase locked loop synthesizer as an oscillator is applied to high-performance MWSCM for general use. Microwave frequency of 24 GHz is applied to the new MWSCM rather than 10 GHz to make the new MWSCM small and light for convenient use of it at fields. Improvement requests on MWSCM for floods-stable velocity measurement, self test, low power consumtion, and waterproof and dampproof-from the users of it has been reflected on the development of the new version of MWSCM.

• Journal of IKEEE
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• v.8 no.2 s.15
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• pp.166-171
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• 2004

This paper describes a CMOS time to digital converter (TDC) that measures the interval between two signals and converts to a digital signal. There are various methods to measure the time interval. But several architectures have a limitation in resolution and in conversion time. Moreover, they have complex algorithms. But the proposed TDC circuit has achieved a high resolution (25ps) by using a high-speed digital sampler and simple algorithm. The sampler detects when input signals comes into the TDC and output is coded. The proposed multiphase clock generator was also implemented to achieve 25p resolution.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.2
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• pp.134-141
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• 2009

The new method is proposed to improve the dynamics of the phase angle detector during abrupt voltage dip caused by a grid fault. Usually, LPF(low pass filter) is used in the feedback loop of SRF(Synchronous Reference Frame) - PLL (Phase Locked Loop) system because the measured grid voltage contains harmonic distortions and sensor noises. A better transient response can be obtained with the proposed design method for SRF-PLL by the analysis of linearized model of the PLL system including LPF. Furthermore, in the proposed method, the controller gain and LPF cut-off frequency are changed from normal value to transient value when the voltage disturbance is detected. This paper shows the feasibility and the usefulness of the proposed methods through the computer simulation and the experiment.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.5
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• pp.333-340
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• 2003

Doppler processing is the heart of pulsed Doppler radar. It gives a clutter elimination and coherent integration. With the improvement of digital signal processors (DPSs), the implementation using them is more widely used in radar systems. Generally, so as for Doppler processor to process the input data in real time, a parallel processing concept using multiple DSPs should be used. This paper implements a programmable Doppler processor, which consists of MTI filter, DFB and square-law detector, using 8 ADSP21060s. Formulating the distribution time of the input data, the transfer time of the output data and the time required to compute each algorithm, it estimates total processing time and the number of required DSP. Finally, using the TSG that provides radar control pulses and simulated target signals, performances of the implemented Doppler processor are evaluated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.208-217
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• 2010

This paper presents a novel 10 GHz bio-radar system based on a frequency multiplier and phase-locked loop(PLL) for non-contact measurement of heartbeat and respiration rates. In this paper, a 2.5 GHz voltage controlled oscillator (VCO) with PLL is employed to as a frequency synthesizer, and 10 GHz continuous wave(CW) signal is generated by using frequency multiplier from 2.5 GHz signal. This paper also presents the noise characteristic of the proposed system. As a result, a better performance and economical frequency synthesizer can be achieved with the proposed bio-radar system. The experimental results shows excellent bio-signal measurement up to 100 cm without any additional digital signal processing(DSP), and the proposed system is validated.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.167-167
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• 2000

전지 재료의 충방전 과정 연구에는 X-선 분말회절(x-ray powder diffraction techniques)과 중성자회절을 많이 사용하였다. 하지만 이러한 분석기술은 long-range order의 구조에 관한 정보를 제공하는데 유용하지만 atomic scale의 구조에 관한 정보를 얻기에는 한계가 있다. Li 전지에서의 전기화학적 반응에서는 cathode 물질에 포함된 전이금속의 산화, 환원 반응에 의한 Li 이온의 intercalation (charge process)과 deintercalation (discharge process) 현상이 일어난다. 이러한 충방전 과정은 알려지지 않은 다양한 형태의 위상 변화를 동반하게 되는데 x-선 이나 중성자를 이용한 powder diffraction techniques 로는 단지 정성적인 결정학적 정보를 얻을 수 있다. 따라서 최근에 원자 단위의 local structure에 관한 정보와 electrochemical state에 관한 정보를 동시에 얻을 수 있는 X-ray Absorption Fine Structure (XAFS) 분석기술을 Li 전지분석에 활용하기 시작하였다. XAFS는 하나의 x-ray 흡수원자에 대해서 주변원자들의 원자구조에 관한 정보와 구성 원소의 electrochemical state에 관한 정보를 얻을 수 있는 분석방법이다. X-ray Induced Electron Emission Spectroscopy (XIEES)는 x-ray에 의해서 방출된 전자를 검출하여 스펙트럼을 얻는 기능을 함축적으로 나타낸 것으로, x-ray를 물질 표면에 조사하여 발생하는 광전자, Auger 전자, 이차전자 등을 전자검출기(Channel Electron Multiplier: CEM)로 검출하는 기능과, 시료를 투과한 x-ray와 시료에서 발생하는 형광 x-ray를 비례계수기로 검출하는 기능을 가지고 있다. 이러한 검출 능력을 바탕으로 EXAFS, XANES, Standing Wave Technique, Elemental Composition Analysis, DXRD, Total Reflection Technique 등을 이용하여 물질을 구성하고 있는 원소의 성분, 미세원자구조, 전자구조에 관한 정보를 얻을 수 있는 새로운 spectrometer이다. 본 연구에서는 자체 개발한 XIEES의 XAFS 기능을 이용하여 여러 가지 방법으로 제조한 LiMn2-xO4와 LiMnO2, MnO2에서 Mn K-absorption edge에 대한 chemical state 변화를 측정하였다. Absorption edge에서 chemical shift를 측정하기 위해서는 방사광 가속기 수준의 에너지 분해능(~0.3eV)이 필요하다. 이번 연구에서는 SiO2(3140) monochromator를 사용하고 여기에 맞는 적절한 parameter를 적용하여 x-ray 에너지 분해능을 포항방사광가속기 수준으로 개선하였다. XIEES에서 얻은 스펙트럼과 포항방사광가속기에서 얻은 스펙트럼을 비교하였다. Chemical shift가 일어나는 경향은 두 실험 결과가 잘 일치하였다.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.271-272
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• 2011

본 논문은 SOGI를 이용한 정상분 전압 검출을 기반으로 하는 SRF(synchronous reference frame)-PLL(phase locked loop) 시스템을 제안한다. 일반화된 2차 적분기의 이중으로 사용하여 QSG(Quadrature-signals generator)의 성능을 개선하여 전압 불평형, 고조파 왜곡 등으로 인한 오차 발생 시에도 빠르고 정확한 위상 검출이 가능하도록 하였으며 본 논문에서 제시한 알고리즘은 PSIM 프로그램 결과를 통하여 타당성을 입증한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.398-399
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• 2009

본 논문에서는 XLPE 전력케이블 접속부의 부분방전을 측정하기 위한 Ferrite 형상에 따른 EM Probe를 설계하였다. 부분방전 펄스의 검출대역를 넓이기 위해 투자율이 2400인 페라이트코어를 사용하여 센서를 제작하였고 형상에 따른 특성을 비교하기위하여 실린더형 Ferrite와 말굽형 Ferrite를 적용하였다. 또한 부분방전 검출능력을 확인하기 위해 상용 HFCT센서의 비교 실험을 통하여 위상특성과 주파수 특성을 분석하였다.