• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.3103-3120
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• 2015

This paper presents a single-phase energy metering chip with built-in calibration function to measure electric power quantities. The entire chip consists of an analog front end, a filter block, a computation engine, a calibration engine, and an external interface block. The key design issues are how to reduce the implementation costs of the computation engine from repeatedly used arithmetic operations and how to simplify calibration procedure and reduce calibration time. The proposed energy metering chip simplifies the computation engine using time-division multiplexed arithmetic units. It also provides a simple and fast calibration scheme by using integrated digital calibration functionality. The chip is fabricated with 0.18-μm six-layer metal CMOS process and housed in a 32-pin quad-flat no-leads (QFN) package. It operates at a clock speed of 4096 kHz and consumes 9.84 mW in 3.3 V supply.

• 한국항공우주학회지
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• 제30권1호
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• pp.147-154
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• 2002

발사체의 발사 시험과 운용에 있어, 예기치 못한 로켓의 오작동으로 인한 인명과 재산의 피해를 예방 또는 최소화하기 위하여 비행안전 시스템은 매우 중요한 역할을 한다. KSR-Ⅲ 발사시 처음으로 운용될 비행안전 시스템은 비행안전 디스플레이 시스템과 비행종단 시스템으로 나뉘어진다. 발사 후 비행중인 로켓의 여러 비행상태와 예상낙하점등은 실시간으로 디스플레이 시스템을 통하여 관찰되며, 로켓이 안전영역을 벗어나거나 로켓의 추적이 불가능하게 될 경우 비행종단시스템은 로켓의 비행을 즉시 중단시키는 역할을 한다. 본 논문에서는 비행안전 시스템 구현에 관하여 수행된 실시간 비행안전 디스플레이 시스템과 비행종단시스템의 개발에 관하여 기술하고 있다.

• 한국전자파학회논문지
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• 제15권6호
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• pp.599-607
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• 2004

이 논문은 PLL주파수 합성기의 루프 대역폭보다 높은 주파수에서 낮은 주파수까지 변화하는 신호에 대한 주파수 변조가 일정한 최대 주파수 편이를 갖도록 하는 단순하면서도 저가의 새로운 주파수 변조회로를 소개하였다. 이 주파수 변조회로는 PLL 안에서의 주파수에 따른 루프 필터의 궤환량을 보상하도록 설계되었고 최대주파수 편이값 조절과 루프와의 상호 간섭을 제거할 수 있도록 설계되었다. 또한 기존의 스펙트럼 분석기로 $\Delta$f(최대 주파수 편이)또는 $\beta$(변조 지수)를 측정하는 방법은 협대역 주파수 변조에서만 유용하여 광대역 주파수에서 측정할 수 있도록 새로운 측정방법을 제안하고 변조 신호 발생기를 이용하여 정확성을 확인하였다. 이런 한 방법으로 설계하여 제작한 회로를 측정하여 기대한 일정한 최대 주파수 편이를 가지는 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.244-246
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• 2001

In a full digital implementation of a current regulator, the voltage output is inevitably delayed due to arithmetic calculation and PWM. In case of the synchronous frame current regulator, the time delay is accompanied by the rotation of frame. In some applications in which the ratio of sampling frequency to output frequency is not high enough, such as high power drive or super high-speed drive, it is known that the effect of rotation of frame during the delay time causes phase and magnitude error in the voltage output. The error degrades the dynamic performance and can bring about the instability of current regulator at high speed. It is also intuitively known that advancing the phase of voltage output can mitigate the instability. In this paper, the instability problems are studied analytically and a compensation method for the error has been proposed. By means of computer simulation and complex root locus analysis, comparative study with conventional methods is carried out and the effectiveness of proposed method is verified.

• Journal of Welding and Joining
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• 제32권1호
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• pp.102-107
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• 2014

SCR(Thyristor) type $CO_2$ welders have widely used for the welding process of heavy industries such as shipbuilding and plant. Since the industrial fields of shipbuilding and plant are usually exposed to severe welding condition with lots of dust, extreme temperature, high humidity and vibration, it is not recommended to use inverter type welder despite its state-of-the-art technology. Many sophisticated functions in the inverter welder may not work due to malfunction of its sensitive components. Hence this study focused on digitalization of SCR $CO_2$ welder by making use of microprocessor for SCR phase control. By this application, fine control of output of the $CO_2$ welding systems is achieved. Also pulse output mode of operation is realized and its verification is carried out with aluminum sample welding. The experimental results showed sound weld bead. The front operation panel provide user with numerical parameter settings and monitors. It will help precise weld process monitoring and control with digital value.

• Current Photovoltaic Research
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• 제1권1호
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• pp.27-32
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• 2013

We investigated the growth mechanism of amorphous-phase Si thin films in order to improve the film characteristics and circumvent photo-degradation effects by implementation of hot-wire chemical vapor deposition. Amorphous silicon thin films grown in a silane/hydrogen mixture can be decomposed by a resistive heat filament. The structural properties were observed by Raman spectroscopy, FTIR, SEM, and TEM. The electrical properties of the films were measured by photo-conductivity, dark-conductivity, and photo-sensitivity. The contents of Si-H and $Si-H_n$ bonds were measured to be 19.79 and 9.96% respectively, at a hydrogen flow rate of 5.5 sccm, respectively. The thin film has photo-sensitivity of $2.2{\times}10^5$ without a crystalline volume fraction. The catalyst behavior of the hot-wire to decompose the chemical precursors by an electron tunneling effect depends strongly on the hydrogen mixture rate and an amorphous Si thin film is formed from atomic relaxation.

• 제어로봇시스템학회논문지
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• 제22권11호
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• pp.967-976
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• 2016

This paper presents a 3D carrier-smoothed GNSS/DR (Global Navigation Satellite System/Dead Reckoning) integrated system for precise ground-vehicle trajectory estimation. For precise DR navigation on sloping roads, the AHRS (Attitude Heading Reference System) methodology is employed. By combining the integrated carrier phase of GNSS and DR sensor measurements, a vehicle trajectory with an accuracy of less than 20cm is obtained even when cycle slip or change of visibility occur. In order to supplement the weak GNSS environment with DR successfully, the DR sensor is precisely compensated for using GNSS Doppler measurements when GNSS visibility is good. By integrating a multi-GNSS receiver with low-cost IMU, a precise 3D navigation system for land vehicles is proposed in this paper. For real-time implementation, a decoupled Kalman filter is employed in the integrated system. Through field experiments, the performance of the proposed system is verified in various road environments, including sloping roads, good-visibility areas, high multi-path areas, and under-ground parking areas.

• 한국전자파학회논문지
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• 제14권11호
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• pp.1176-1183
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• 2003

본 논문에서는 1.6 ㎓ PCS 대역 초소형 전압제어발진기를 LTCC 기술을 이용하여 구현하였다. 상용부품들을 사용하여 VCO 회로를 설계하고, LTCC 기판 내부에 실장될 인덕터, 캐패시터들을 시뮬레이션을 통하여 최적으로 설계하였다. 설계된 수동소자들은 시뮬레이션을 위하여 등가회로로 모델링한 후 회로 파라메타를 추출하였다. 모델링된 내장형 부품과 21층 구조의 LTCC 기 판을 이용하여 전압제어 발진기를 설계하였으며, 4.0${\times}$4.0${\times}$1.6 ㎣ 크기의 VCO를 제작하였다. 제작된 전압제어 발진기의 동작전압은 2.7 V, 소모전류는 최대 8.5 ㎃ 이하이었으며, 동작주파수는 1,620∼l,650 MHz이다. 또한 동작주파수 내에서의 위상잡음특성은 100 KHz offset에서 -ll2.67 ㏈c/Hz의 우수한 특성을 지녔으며, -30 ㏈ 이상의 고조파억압특성을 보였다.

• Journal of information and communication convergence engineering
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• 제9권1호
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• pp.32-37
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• 2011

In dispersion management (DM) and optical phase conjugation applied into optical transmission links with multi fiber spans for minimizing the impact of nonlinearity and group velocity (GVD), implementation possibility of DM using only one fiber span for pre- or postcompensation was assessed as a function of duty cycle of RZ pulse and residual dispersion per span (RDPS). It is confirmed that DM with optimal net residual dispersion (NRD) controlled by only one fiber span could be sufficiently applied into optical transmission links, though optimal NRD is more increased than that in transmission links with the general DM scheme of pre- and postcompensation. Thus, it is expected that optical transmission system is simply designed and implemented by applying the proposed DM scheme into real optical transmission links. Also, it is confirmed that the advantageous duty cycle of RZ is 0.5 and RDPS is setting to be small value for the effective transmitting wide signal wavelength range in optical links with optimal NRD controlled by only one fiber span.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.688-698
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• 2018

Quasi Z-Source Multilevel Inverter (QZMLI) topology has attracted grid connected Photovoltaic (PV) systems in recent days. So there is a remarkable research thrust in switching techniques and control strategies of QZMLI. This paper presents the mathematical analysis of Phase shift- Pulse Width Amplitude Modulation (PS-PWAM) for QZMLI and emphasizes on the advantages of the technique. The proposed technique uses the maximum and minimum envelopes of the reference waves for generation of pulses and proportion of it to generate shoot-through pulses. Hence, it results in maximum utilization of input voltage, lesser switching loss, reduced Total Harmonic Distortion (THD) of the output voltage, reduced inductor current ripple and capacitor voltage ripple. Due to these qualities, the QZMLI with PS-PWAM emerges to be the best suitable for PV based grid connected applications compared to Phase shift-Pulse Width Modulation (PS-PWM). The detailed math analysis of the proposed technique has been disclosed. Simulation has been performed for the proposed technique using MATLAB/Simulink. A prototype has been built to validate the results for which the pulses were generated using FPGA /SPARTAN 3E.