• JSTS:Journal of Semiconductor Technology and Science
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• 제16권4호
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• pp.528-533
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• 2016

A low voltage high PSRR CMOS Bandgap circuit capable of generating a stable voltage of less than 1 V (0.8 V and 0.5 V) robust to Process, Voltage and Temperature (PVT) variations is proposed. The high PSRR of the circuit is guaranteed by a low-voltage current mode regulator at the central aspect of the bandgap circuitry, which isolates the bandgap voltage from power supply variations and noise. The isolating current mirrors create an internal regulated voltage $V_{reg}$ for the BG core and Op-Amp rather than the VDD. These current mirrors reduce the impact of supply voltage variations. The proposed circuit is implemented in a $0.35{\mu}m$ CMOS technology. The BGR circuit occupies $0.024mm^2$ of the die area and consumes $200{\mu}W$ from a 5 V supply voltage at room temperature. Experimental results demonstrate that the PSRR of the voltage reference achieved -118 dB at frequencies up to 1 kHz and -55 dB at 1 MHz without additional circuits for the curvature compensation. A temperature coefficient of $60 ppm/^{\circ}C$ is obtained in the range of -40 to $120^{\circ}C$.

• Transactions on Electrical and Electronic Materials
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• 제9권3호
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• pp.123-127
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• 2008

The paper is to solve the problem of existing audio signal transfer system which has a difficulties of system organization and the increase of additional install cost and unfriendly interior. To solve the existing system, we drew the new audio signal transfer system based on PLC and evaluated it. A transmitter and a receiver were designed using the PLC chip INT5500CS. An audio signal transfer system was configured with a CD player to which audio signals are sent from the transmitter and a speaker connected to the receiver. For performance evaluation of this system, a USBPre external sound card and Smaart Live 5 which is a PC-based sound measuring program were added. As a result of our experiment, the measured signal level is $2{\sim}3$ dB lower than reference signal, latency is 16.69 ms, and the specific character of coherency is bad in high frequency band. Otherwise, this system transmits and receives signals over 90 % in good condition as a result of measuring pink noise, frequency (1 kHz), and phase, magnitude. In view of the result so far achieved, the system designed this study has excellent performance, it resolves defect of existing audio signal transfer system.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.389-395
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• 2012

In this paper, we analyzed the frequency spectrum of the electromagnetic waves radiated by an electric discharge as a basic study to develop an on-line diagnostic technique for power equipment installed inside closed-switchboards. In order to simulate local and series arc discharges caused by an electric field concentration and poor connections, three types of electrode systems were fabricated, consisting of needle and plane electrodes and an arc generator meeting the specifications of UL 1699. The experiment was carried out in an electromagnetic anechoic chamber, and the measurement system consisted of a PD free transformer, a loop antenna with a frequency bandwidth of 150 kHz-30 MHz, an ultra log periodic antenna with a frequency bandwidth of 30 MHz-2 GHz, and an EMI test receiver with a frequency bandwidth of 3 Hz-3 GHz. According to the experimental results, the frequency spectra of the electrical discharges were widely distributed across a range of 150 kHz-400 MHz, depending on the defects, while commonly found between 150 kHz and 10 MHz. Therefore, considering the ambient noise and antenna characteristics, the best frequency bandwidth for a measurement system to monitor abnormal conditions by detecting electromagnetic waves in closedswitchboards is 150 kHz-10 MHz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1957-1959
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• 2000

The PD measurement method is very useful to detect insulation degradation. Recently, the HFPD(High Frequency Partial Discharge) measurement testing is widely used in partial discharge measurement of HV machines because HFPD measurement testing receives less influence of external noise and has a merit of good sensitivity. Therefore it is very useful method compare to previous conventional PD testing method and effective diagnosis method in power transformer that requires in-service diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In this study, simulated transformer is manufactured and HFPD occurred from simulated transformer is measured with broad band antenna and active-line RF measurement system in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages. Also the PD pattern which was measured with EMC analyzer and RF measurement system is compared.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.173-176
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• 2005

본 연구는 2005. 7. 1 시행 공포된 전파법 시행령 개정안 내용 중 전력선통신설비의 주파수 대역이 9kHz${\sim}$450kHz에서 그 상한선 범위가 30MHz까지 확대 시행됨과 관련하여 전력선통신설비가 단파대 무선통신에 혼신을 야기할 수 있음에 따라 그 영향여부를 평가하는 방법을 제시하고 향후 전력선통신설비를 운용함에 있어서 단파대 무선통신에 영향을 회피하기 위한 대책방안을 제안하는데 있다. 전력선통신의 운용주파수 확대와 관련하여 정보통신부 전파연구소에서 전력선통신이 단파대 무선통신의 혼신여부에 대하여 측정 관찰해 왔으며 그 간섭정도를 판단하기 위해 노력해 왔다. 본 연구에서는 전파수신기, 신호발생기 및 SINAD(Signal to Noise and Distortion) Meter를 사용한 측정방법을 제시하고 있으며 이는 무선(RF : Radio Frequency) 환경에 적합한 측정방법으로 기존의 EMC(electromagnetic compatibility) 환경에 의한 한계를 극복할 수 있다. 또한, 본 연구에서는 전력선통신설비가 단파대 해상이동통신에 영향을 최소화하기 위하여 보호구역을 설정 또는 해당 주파수에 대하여 운용금지하는 방안을 제시함으로써 무선통신환경을 보호하는데 그 목적이 있다.

• 한국ITS학회 논문지
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• 제8권2호
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• pp.83-90
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• 2009

백색 LED(Light Emitting Diode:발광다이오드)는 고휘도, 향상된 안정성, 낮은 전력 소비, 그리고 긴 수명 등 유리한 특성을 제공한다. LED는 전기 신호를 광신호로 변환시킴으로써 광통신 실내 무선 광 조명실뿐만 아니라, 무선 광 통신 시스템에도 사용되는 전자 소자이다. 현재 이러한 백색 LED에 대해서 다양한 연구가 진행 중이며, 본 논문에서는 이러한 백색 LED를 이용한 VLC(Visible Light Communication:가시광통신)의 다중 접속 방식을 논의한다. 제안된 시스템에서는 현 VLC 시스템의 간섭을 줄이고, 수용량을 늘리기 위해 CDMA(Code Division Multiple Access:코드 분할 다중 접속)를 VLC시스템에 적용한다. 또한 AWGN(Additive White Gaussian Noise) 채널과 Diffuse 채널에서의 OOK(On-off keying) 변조와 BPSK 변조를 사용한 VLC-CDMA통신 시스템을 비교해봄으로써 OOK 변조의 우수성을 결과의 분석을 통하여 나타내었다. 그리고 다중경로환경에서와 AWGN환경에서의 BER을 비교함으로써 다중경로에 의한 간섭의 해결의 중요성을 검토한다. 다중 접속 방식으로 인한 ISI(Inter Symbol Interference)를 제거하여 시스템의 효율을 높이기 위해 Directed LOS(Line Of Sight)와 Diffuse Link를 가정하여 광 확산 코드인 OOC(Optical Orthogonal Code: 광 직교 코드)를 적용한 VLC-CDMA를 제안하고, 성능 분석을 제시한다.

• 대한전자공학회논문지SD
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• 제48권2호
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• pp.7-13
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• 2011

본 논문에서는 디지털 위상고정루프(All-digital PLL)를 구성하는 핵심 블록인 시간-디지털 변환기(Time-to-Digital Converter)를 제안하고 구현하였다. 본 연구에서는 게이티드 링 오실레이터 시간-디지털 변환기(GRO-TDC)의 기본 구조에 버니어 지연단(VDL)을 이용하여 다중 위상을 얻음으로써 보다 높은 해상도를 얻을 수 있는 구조를 제안하였다. 게이티드 링 오실레이터(GRO)는 총 7개의 지연셀을 사용하였고, 버니어 지연단(VDL) 3단을 이용하여 총 21개의 다중 위상을 사용하여 시간-디지털 변환기(TDC)를 설계하였다. 제안한 회로는 $0.13{\mu}m$ 1P-6M CMOS 공정을 사용하여 설계 및 구현하였다. 측정결과, 제안한 시간-디지털 변환기(TDC)의 최대 입력 주파수는 100MHz이고, 해상도는 26ps로 측정되었으며, 출력은 8-비트이며, 검출이 가능한 최대 위상 차이는 5ns의 위상 차이까지 검출이 가능하였다. 전력 소비는 측정된 Enable 신호의 크기에 따라 최소 8.4mW에서 최대 12.7mW로 측정되었다.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2018-2030
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• 2015

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.675-682
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• 2017

New government, the market for stationary fuel cell systems in domestic is expected to expand in line with the policy for expanding new and renewable energy. In order to promote and expand the domestic market for stationary fuel cell systems, it is required to do research and develop for cost reduction and efficiency improvement technologies through the localization of BOP. In this study, the safety performance including the power consumption, flow rate, noise and air-tightness of the domestic fuel booster blower and the foreign fuel booster blower was evaluated and the performance improvement of the domestic blower was confirmed. As a result of the power consumption measurement and the flow rate according to the back pressure of the A company 2nd prototype and B company, the values were 73 W, 27 LPM, and 55 W, 25 LPM. These results are attributed to the improvement of performance through design changes such as CAM angle and diaphragm material.

• 방송공학회논문지
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• 제13권5호
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• pp.612-621
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• 2008

이용 가능한 데이터 영역과 전송전력 등 다양한 제한 요소들로 인하여 지그비 통신의 기술규격에는 음성통신에 대한 기준 사양이 포함되지 않았다. 본 논문에서는 지그비의 기반인 IEEE 802.15.4 표준에 적용하기 위한 음성부호화 기법이 제시된다. 여기서는 높은 압축율과 파형 복구능력이 우수한 파형부호기의 실현이 필수적이다. 이를 위하여 제시된 방법에서는 다단 이산 웨이블릿변환과 두 가지 펄스부호변조로 구성된 이진부호기가 사용된다. 이론적인 분석과 실내 무선 환경에서의 모의실험 결과 2단 웨이블릿변환을 적용한 경우가 압축율과 음성신호 복구능력 면에서 가장 적합한 것으로 판단된다. 직선전파경로 성분이 지배적인 경우 제시된 방법은 중간 정도의 신호 대 잡음비에서도 만족스러운 복구능력을 가진다. 따라서 제시된 음성부호화 방법은 향후 지그비를 이용한 음성통신의 표준 선정에 참고 가능한 기술이 될 수 있을 것으로 사료된다.