• ETRI Journal
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• 제30권3호
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• pp.377-382
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• 2008

A novel power amplifier for a polar transmitter is proposed to achieve better spectral performance for a wideband envelope signal. In the proposed scheme, 2-bit sigma-delta (${\Sigma}{\Delta}$) modulation of the envelope signal is introduced, and the power amplifier configuration is modified in a binary form to accommodate the 2-bit digitized envelope signals. The 2-bit ${\Sigma}{\Delta}$ modulator lowers the noise of the envelope signal by fine quantization and thus enhances the spectral property of the RF signal. The Ptolemy simulation results of the proposed structure show that the spectral noise is reduced by 10 dB in a full transmit band of the EDGE system. The dynamic range is also enhanced. Since the performance is improved without increasing the over-sampling ratio, this technique is best suited for wireless communication with high data rates.

• KIEE International Transactions on Power Engineering
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• 제3A권4호
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• pp.214-221
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• 2003

In view of the fact that gas insulated switchgear (GIS) is an important piece of equipment in a substation, it is highly desirable to continuously monitor the state of equipment by measuring the partial discharge (PD) activity in a GIS, as PD is a symptom of an insulation weakness/breakdown. However, since the PD signal is relatively weak and the external noise makes detection of the PD signal difficult, it therefore requires careful attention in its detection. In this paper, the algorithm for detection of PD in the GIS using the wavelet transform (WT) is proposed. The WT provides a direct quantitative measure of the spectral content and dynamic spectrum in the time-frequency domain. The most appropriate mother wavelet for this application is the Daubechies 4 (db4) wavelet. 'db4', the most commonly applied mother wavelet in the power quality analysis, is very well suited to detecting high frequency signals of very short duration, such as those associated with the PD phenomenon. The proposed algorithm is based on utilizing the absolute sum value of coefficients, which are a combination of D1 (Detail 1) and D2 (Detail 2) in multiresolution signal decomposition (MSD) based on WT after noise elimination and normalization.

• 한국멀티미디어학회논문지
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• 제18권3호
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• pp.401-407
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• 2015

In this paper, we propose the method to eliminate EMI (Electro-Magnetic Interference) in ELF (Extremely Low Frequency) band below 2 KHz for extending the gesture-recognition distance of smart TVs to more than 3m using electric potential sensor. First, we measure the electric field generated from the back panel of a TV and propose the effective arrangement of two sets of differential sensors as well as the shielding method using metal fiber. Also, we eliminate the PLN (Power Line Noise) and other noise generated from the TV and sensors as well as surrounding environments using filters. Using the proposed EMI eliminating methods, we evaluate displacement ratio on measured signals according to distance between sensors and a moving hand. Experiment results show that our proposed method can extend the hand-gesture sensing distance using EPS (Electric Potential Sensor) up to more than 3m, which is enough to satisfy applicability of EPS based remote control to Smart TVs.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1212-1217
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• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.

• 자연과학논문집
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• 제8권1호
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• pp.5-15
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• 1995

IRR 적응 휠터의 공식오차 방식은 지역 최소값에 관계없이 전역 최소값에 수렴하며 안정성이 높다. 그러나 공식오차 방식은 입력 신호에 잡음이 섞여 경우 예측계수가 바이어스 되는 문제가 있다. 본 논문에서는 사전에 잡음에 대한 지식이 없이 바이어스가 없는 예측계수를 얻을 수 있는 새로운 공식 오차 방식을 위한 알고리즘을 제안한다. 이 알고리즘은 공식오차를 스므딩하는 방식을 이용하여 입력에 추가되는 잡음이 백색잡음인 경우 바이어스 없이 계수를 예측할 수 있다. 시뮬레이션을 통해 새로운 알고리즘이 공식오차의 중요한 장점인 빠른 수렴속도와 안정성을 유지하며 바이어스를 효율적으로 제거함을 볼 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1157-1164
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• 2003

Dynamic Load/unload (L/UL) mechanism is an alternative to the contact start stop (CSS) technology which eliminates stiction and wear failure modes associated with CSS. Other benefits of L/UL include increased areal density due to smooth disk surfaces, thinner overcoats, and lower head flying height Improved shock resistance due to elimination of head slap, and reduced power consumption. Inertia latch mechanism becomes important for mobile disk drives because of non operating shock performance. Various types of latch designs have been introduced in hard disk drives to limit a rotary actuator from sudden uncontrolled motion. In this paper, a single spring inertia latch is introduced for a small form optical disk drive, which uses a rotary actuator for moving an optical pick-up. A new small inertia latch with single spring is designed to ensure both feasible and small size. The shock performance of the new inertia latch is experimentally verified.

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.519-522
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• 2008

As industry of a semiconductor and LCD industry have been rapidly growing, precision technologies of machining such as etching and 3D measurement are required. Stylus has been important measuring method in traditional manufacturing process. However, its disadvantages are low measuring speed and damage possibility at contacting point. To overcome mentioned disadvantage, non-contacting measurement method is needed such as PMP(Phase Measuring Profilometry), WSI(white scanning interferometer) and Confocal Profilometry. Among above 3 well-known methods, WSI started to be applied to FPD(flat panel display) manufacturing process. Even though it overcomes 21t ambiguity of PMP method and can measure objects which has specular surface, the measuring speed and vibration coming from manufacturing machine are one of main issue to apply full automatic total inspection. In this study, We develop high speed WSI system and algorithm to reduce unknown noise. The developing WSI and algorithm are implemented to measure 3D surface of wafer. Experimental results revealed that the proposed system and algorithm are able to measure 3D surface profile of wafer with a good precision and high speed.

• 디지털콘텐츠학회 논문지
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• 제14권1호
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• pp.117-124
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• 2013

본 논문에서는 고정된 카메라로부터 획득한 연속된 이미지 시퀀스를 이용하여 조명 변화에 강건한 운동 객체를 추출하는 방법을 제안한다. 운동 객체 추출 시 가장 문제가 되는 것은 조명과 잡음에 의한 영향이다. 시간의 변화에 따른 조명의 변화로 어두운 영역에 의한 가려짐 현상이 발생할 경우 객체 영역을 판단하기가 쉽지 않다. 본 논문에서는 잡음에 강건한 방법인 가우시안 혼합 모델을 이용하여 운동객체를 추출 하였으며, 조명에 대한 영향을 최소화 하고자 대표 조명 영상을 정의하고 이를 통하여 입력 영상에 대한 조명 성분을 제거하는 방법을 제안한다.

• 전기전자학회논문지
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• 제23권2호
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• pp.722-726
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• 2019

본 논문에서는 고주파 영역에서의 전원잡음제거 (PSR) 특성이 개선된 low drop-out (LDO) 레귤레이터를 제안한다. 특히, PMOS 전력 스위치의 유한한 출력저항을 관통하는 고주파 전원잡음을 상쇄하기 위해 출력저항이 큰 NMOS 트랜지스터를 보상 회로로 추가하였다. 보상 트랜지스터에 의한 전원잡음제거는 해석적으로 설명하여 개선에 대한 방향을 제시하였다. $0.35{\mu}m$ 표준 CMOS 공정으로 회로를 제작하고 Spectre 시뮬레이션을 수행하여 10MHz에서 기존의 LDO 레귤레이터 대비 26dB의 PSR 개선을 확인하였다.

• 한국음향학회지
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• 제43권2호
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• pp.145-151
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• 2024

함정 선체부착형 수동소나체계는 최근 표적탐지성능을 향상시키고자 함내 진동유기 소음을 제거하려는 연구가 활발히 진행중이다. 본 연구진은 신호처리의 관점에서 음향센서와 진동센서가 설치된 복합센서를 이용한 음향-진동 정합기법을 개선책으로 제시한다. 본 논문에서는 정합기법의 이론적 배경에 대해 기술한 후, 그것이 다중물리 유한 요소해석 상에서 실현됨을 보였다. 나아가 정합기법을 센서 시스템에 적용할 시의 표적신호 수신감도 상승 및 진동유기 소음 제거 성능을 산출하였으며, 정합기법의 실용성과 향후 연구방향에 대해 논하였다.