• 조명전기설비학회논문지
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• 제12권4호
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• pp.146-154
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• 1998

교류 전원선로에서 발생하는 수 kHz에서 수십 MHz에 이르는 광대역의 주파수특성올 가진 전원노이즈는 전기, 전자장비의 정상적인 동작에 많은 장해요소가 되고 있으며 이들 전도노이즈를 억제하기 위한 부품으로 현재 써어지 억제부품과 필터가 적용되고 있다. 그러나 기존의 대책부품은 전력공급선과 노이즈 피해회로를 전기적으로 완전히 절연시킬 수 없기 때문에 전도 노이즈 중에서 가장 크게 발생하는 공통모드 노이즈 억제성능이 제한 되고 있다. 본 논문에서는 절연변압기의 절연 특성에 정전 차폐를 추가함으로써 전도노이즈 및 써어지 억제기능이 우수한 NCf의 설계방법올 제시하였으며, 설계 제작된 1[kVA] NCT 시작품의 모의 등가회로에 대한 써어지 해석결과와 실험 측정 결과를 상호 비교하여 제안된 모델의 특성을 비교 평가하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.942-947
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• 2001

This paper provides a stability analysis of the transverse vibration of a spinning disk under the torque fluctuation from a permanent magnetic motor. An analytical model has been formulated for a flexible annular disk with its spinning velocity varying harmonically with the same frequency as the cogging torque. A perturbation method based on multiple time scales is applied to perform the stability analysis. Based on expressions for the amplitude and frequency of the parametric excitation, stability boundaries are determined in terms of a nominal spindle velocity, the least common multiple of poles and slots, the magnitude of torque fluctuation and the modal characteristics of. the disk. The stability diagrams predicted by perturbation have been verified numerically using the Floquet theory, which is in good agreement. In conclusion, the fluctuation in spinning velocity is found to affect the stability of the transverse vibration of a rotating disks. The results of this work can be applied to high precision spindle systems such as computer storage systems.

• Journal of Power Electronics
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• 제10권4호
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• pp.342-350
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• 2010

Randomizing the switching frequency (RSF) to reduce the electromagnetic interference (EMI) of switching power converters is a well-known technique that has been previously discussed. The randomized pulse position (RPP) technique, in which the switching frequency is kept fixed while the pulse position (the delay from the starting of the switching cycle to the turn-on instant within the cycle) is randomized, has been previously addressed in the literature for the same purpose. This paper presents a double-hybrid technique (DHB) for EMI reduction in dc-dc switching regulators. The proposed technique employed both the RSF and the RPP techniques. To effectively spread the conducted-noise frequency spectrum and at the same time attain a satisfactory output voltage quality, two parameters (switching frequency and pulse position) were randomized, and a third parameter (the duty ratio) was controlled by a digital compensator. Implementation was achieved using field programmable gate array (FPGA) technology, which is increasingly being adopted in industrial electronic applications. To evaluate the contribution of the proposed DHB technique, investigations were carried out for each basic PWM, RPP, RSF, and DHB technique. Then a comparison was made of the performances achieved. The experimentally investigated features include the effect of each technique on the common-mode, differential-mode, and total conducted-noise characteristics, and their influence on the converter’s output ripple voltage.

• 전력전자학회논문지
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• 제6권6호
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• pp.546-555
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• 2001

본 논문에서는 PWM 인버터-유도전동기 구동시스템의 전도노이즈 저감을 위한 출력필터 설계에 관한 연구를 수행하였다. 전도노이즈는 고전압 입력, 고용량 구동시스템 그리고 긴 전동기 터미널 등의경우에서 크게 문제가 된다. 고압력을 갖는 시스템에서는 높은 압력에 비례한 직류 링크 전압을 갖고 이에 따라 스위칭 dv/dt가 순간 최대 CM 접지전류를 발생시킨다. 그러므로 이에 대한 대책이 필요하다. 따라서 최근 산업 현장에서 많이 사용되고 있는 PWM 인버터를 설계 제작하여 유도전동기를 구동하고 이에 따라 발생되는 전도노이즈 성분을 감쇠 시킬 수 있는 출력필터를 설계하였고 제작 및 실험을 통하여 그 타당성을 입증하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권5호
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• pp.675-681
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• 2016

A 41dB gain control range $6^{th}$-order band-pass receiver front-end (RFE) using CMOS switched frequency translated impedance (FTI) is presented in a 40 nm CMOS technology. The RFE consists of a frequency tunable RF band-pass filter (BPF), IQ gm cells, and IQ TIAs. The RF BPF has wide gain control range preserving constant filter Q and pass band flatness due to proposed pre-distortion scheme. Also, the RF filter using CMOS switches in FTI blocks shows low clock leakage to signal nodes, and results in low common mode noise and stable operation. The baseband IQ signals are generated by combining baseband Gm cells which receives 8-phase signal outputs down-converted at last stage of FTIs in the RF BPF. The measured results of the RFE show 36.4 dB gain and 6.3 dB NF at maximum gain mode. The pass-band IIP3 and out-band IIP3@20 MHz offset are -10 dBm and +12.6 dBm at maximum gain mode, and +14 dBm and +20.5 dBm at minimum gain mode, respectively. With a 1.2 V power supply, the current consumption of the overall RFE is 40 mA at 500 MHz carrier frequency.

• 전자공학회논문지 IE
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• 제47권4호
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• pp.53-58
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• 2010

본 논문에서는 색채 공간의 불균일도를 반영한 3차원 색채공간에서의 심벌판정 기법을 제안하고, 2차원 색채 공간에서의 심별 판정 기법과의 BER 성능을 비교 분석한다. 제안한 방법은 색채 공간에서의 심벌 영역을 3차원 RGB 공간에서 색채공간으로 변환하여 구하기 때문에 불균일도를 반영하고 있으면서 Y값에 해당하는 한 개의 차원이 증가함으로써 생기는 이득으로 인하여 2차원 색채 공간 기반 판정기법에 비하여 BER 측면에서 우수한 성능을 보여준다. 본 논문에서는 AWGN 및 common mode noise의 채널 환경에서 2차원 색채 공간 기반 심벌판정 기법과 비교하여 제안한 3차원 색채 공간 기반 심벌판정 기법의 BER 성능 개선 가능성을 수치적 시뮬레이션을 통해 입증한다.

• 대한의용생체공학회:의공학회지
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• 제20권2호
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• pp.205-212
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• 1999

수술실에서 수술도중 환자의 뇌파를 관찰하고자 할 경우에 전기수술기를 사용하게 되면 매우 높은 주파수와 큰 전압의 전기적 잡음이 발생하게 되며, 기존의 뇌파측정기는 이 잡음에 의해서 포화되어 뇌파 측정이 불가능하다. 본 연구에서는 고신뢰도의 뇌파 측정용 CSA 시스템을 구성하기 위하여 전기수술기의 간섭이 적은 양극 뇌파증폭기를 개발하고자 하였다. 개발된 양극 뇌파 증폭기는 balanced filter를 사용하여 전기수술기의 잡음이 뇌파 증폭기의 입력으로 들어가는 것을 줄이도록 하였으며, 전치증폭기의 전원과 신호를 접지와 분리하여 전기수술기에서 나온 전류가 뇌파 증폭기를 통해 접지로 흘러 들어가는 경로를 차단하였고, 높은 주파수에서도 CMRR 특성이 좋은 차동증폭기를 사용하여 고주파 성분의 공통 성분 잡음을 제거함으로써 전기수술기의 잡음을 상당히 줄일 수 있었다. 이와 같이 개발된 양극 뇌파증폭기는 고이득, 저잡음, 높은 CMRR, 고입력 임피던스, 낮은 열잡음 등의 특성을 가지므로 순수한 뇌파의 측정에 유용하며, 전기수술기를 사용할 경우에도 지속적으로 뇌파를 측정할 수 있는 고신뢰도의 CSA 시스템의 구현에 이용할 수 있다.

• 전기전자학회논문지
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• 제23권3호
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• pp.917-924
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• 2019

This paper presents a wideband low noise amplifier (LNA) that is suitable for LTE-Advanced and 5G communication standards employing carrier aggregation (CA). The proposed LNA encompasses a common input stage and a dual output second stage with a buffer at each distinct output. This architecture is targeted to operate in both intra-band (contiguous and non-contiguous) and inter-band CA. In the proposed design, the input and second stages employ a gm enhancement with resistive feedback technique to achieve self-biasing, enhanced gain, wide bandwidth as well as reduced noise figure of the proposed LNA. An up/down power controller controls the single input single out (SISO) and single input multiple outputs (SIMO) modes of operation for inter-band and intra-band operations. The proposed LNA is designed with a 45nm CMOS technology. For SISO mode of operation, the LNA operates from 0.52GHz to 4.29GHz with a maximum power gain of 17.77dB, 2.88dB minimum noise figure and input (output) matching performance better than -10dB. For SIMO mode of operation, the proposed LNA operates from 0.52GHz to 4.44GHz with a maximum voltage gain of 18.30dB, a minimum noise figure of 2.82dB with equally good matching performance. An $IIP_3$ value of -6.7dBm is achieved in both SISO and SIMO operations. with a maximum current of 42mA consumed (LNA+buffer in SIMO operation) from a 1.2V supply.

• 소음진동
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• 제9권2호
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• pp.258-264
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• 1999

The purpose of this paper is to investigate the damping behavior of a flexible joint. The slip at a structrual joint is selected at the tips of two identical cantilever beams adjoining each other. Both the direction of normal force and its magnitude varies due to the global deformation of the structure from mode to mode in the friction model. The friction dependent on vibration displacements resultsin the same functional behavior of the hysteretic material damping. Linearized energy loss factors are obtained as functions of both linear and torsional spring stiffness for their groups of symmetric and anti-symmetric modes, respectively. Experimental measurements as made for comparisons with analytical estimations by controlling the magnitude of fastening torque in the fastener, Hi-Lite. Trends on damping levelsmeasured in a very common vibration test method make an excellent agreement on the estimated damping levels.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.387-392
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• 2009

Measurement of dynamic characteristics are widely used to detect defects in mechanical or civil structures. The most common approach is to measure changes in frequency spectrum or mode shapes using accelerometers. An alternative to using mode shapes is using stain modes. Strain is more sensitive to local defects than displacement, and hence stain modes measurement is an efficient in structural health monitoring. This paper deals with dynamic monitoring of a beam structure using strain sensors. Resistive strain gages and FBG strain gages are used and their characteristics are compared. It has been known that resistive strain gages are week to EMI environment and suffers from noise at high frequency range. It has been shown that the FBG sensor is a good alternative that overcomes such difficulties.