• ETRI Journal
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• 제31권6호
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• pp.755-764
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• 2009

This paper presents a switched self-biasing and a tail current-shaping technique to suppress the 1/f noise from a tail current source in differential cross-coupled inductance-capacitance (LC) voltage-controlled oscillators (VCOs). The proposed LC VCO has an amplitude control characteristic due to the creation of negative feedback for the oscillation waveform amplitude. It is fabricated using a 0.13 ${\mu}m$ CMOS process. The measured phase noise is -117 dBc/Hz at a 1 MHz offset from a 4.85 GHz carrier frequency, while it draws 6.5 mA from a 0.6 V supply voltage. For frequency tuning, process variation, and temperature change, the amplitude change rate of the oscillation waveform in the proposed VCO is 2.1 to 3.2 times smaller than that of an existing VCO with a fixed bias. The measured amplitude change rate of the oscillation waveform for frequency tuning from 4.55 GHz to 5.04 GHz is 131 pV/Hz.

• 천문학회보
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• 제37권2호
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• pp.228.1-228.1
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• 2012

Digital waveform generation technology for SAR payload can be divided into DDS(Direct Digital Synthesizer) method and Memory Mapped(M/M) method. DDS is the single chip which consists of the Sine Table, NCO(Numerically Controlled Oscillator), DAC, and so on. DDS method is a very simple method because the circuit configuration is not complex but has a disadvantage that can not control phase and amplitude easily by using NCO. M/M method has the complexity of the circuit configuration because it requires the memories which stores the waveforms, the control circuits, and DAC. And this method should apply the high interface technology for being compatible with the wide bandwidth of the digital signal and has the difficulty for PCB design because the number of the signal lines should be increased according to the number of the data bits for DAC. Although it has several disadvantages, this method has the capability of pre-distortion function which can compensate the phase and amplitude characteristics of the system and also has an excellent advantage to make any arbitrary waveform, so this method is considered as an important technology with DDS method. This research describes the technological trends of the waveform generator for the SAR payload and analyzes the characteristics of the technology.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.260-265
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• 1996

The purpose of this study was to implemented a general purpose programmable nerve stimulator system as a research tool for studying psychophysiological performance associated with various stimulation waveform. This system is composed of hardware and software, the former are the personal computer(180586) and control unit(one-chip microprocessor, D/A converter, digital output), the latter are programmed in VISUAL BASIC and ASSEMBLY Which are programmed for the programmable nerve stimuli pattern editor and communication interface, waveform preprocessing, and stimuli generator. The control unit which is entrolled by the personal computer is capable of delivering the programmable nerve stimuli waveform. This system has research potential for determining the effect of various neuromuscular blockade in alternated physiological stat is.

• 대한후두음성언어의학회지
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• 제16권1호
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• pp.5-9
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• 2005

Background and Objectives : Glottal area waveform(GAW) shows the plot of glottal area versus time through the 1 cycle. This study is designed to see how it can be applied to laryngeal patients. Material and Methods : A GAW analysis was peformed on 11 patients before and after surgery and 22 persons without laryngeal problems were recruited for control. Acoustic and aerodynamic analysis with VHI(voice handicap index) evaluation were performed. Results. Significant changes in baseline offset, gross closing rate and VHI were observed postoperatively. Other parameters were changed but insignificant. Conclusion : GAW maybe used to evaluate patient with voice problems.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.728-731
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• 2009

A negative waveform having inverted polarity of conventional waveform during reset and sustain periods was proposed to improve the driving characteristics. In order to control the negative wall-charge distribution, a positive bias on the scan electrode was applied during reset period. Compared to 0 V scan-bias condition, at 8 V scan-bias the formative time lag was improved about 23.95 % and the average time lag was improved about 14.91 %. All experiments were performed with the 42-inch PDP module in XGA resolution.

• 대한의용생체공학회:의공학회지
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• 제18권1호
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• pp.25-36
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• 1997

To regulate cardiac output of the Total Artificial Heart(TAH) physiologically, the hemodynamic information must be toed back to the controller. So far, our group has developed an automatic cardiac output control algorithm using the motor current waveform, It is, however difficult to detect the preload level such as a filling status of ventricular inflow and the variation of atrial pressures within normal physiologic range(0-15 mmHg) by analyzing the motor current which simultaneously reflects the afterload effect. On the other hin4 the interventricular volume pressure(IVP) which is not influenced by arterload but by preload is a good information source for the estimation of preload states. In order to find the relationship between preload and IVP waveform, we set up the artificial heart system on the Donovan type mock circulatory system and measured the IVP waveform, right and left atrial pressures, inflow and outflow waveforms and the signals represented the information of moving actuator's position. We shows the feasibility of estimating the hemodynamic changes of inflow by using IVP waveform. fife found that the negative peak value of IVP waveform is linearly related to atrial pressures. And we also found that we could use the time to reach the negative peak in IVP waveform, the time to open outflow valve, the area enclosed IVP waveform as unfu parameters to estimate blood filling volume of diastole ventricle. The suggested method has advantages of avoiding thrombogenesis, bacterial niche formation and increasing longterm reliability of sensor by avoiding direct contact to blood.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.581-586
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• 2000

Gas metal arc welding(GMAW) uses a continuously fed electrode as a filler metal. The arc is shielded from atmospheric contamination by an inert gas active or inert/active gas mixture delivered through the welding gun and cable assembly. The recent research topics on $CO_2$ are welding machines are focused mainly on the reduction method of generated spatter by using new type consumable electrode metal or inverter control method. The various current waveform control methods have been researched for welding performance improvement. Until now current waveform control methods reduce to spatter occurred by instantaneous short circuiting,. but these methods is drawback that no reduce spatter occurred by arc reignition. In this paper the previous arc reignition current control method for welding performance improvement of inverter arc welding machine is studied and compared the various current control methods with the previous arc reignition current control method.

• 대한원격탐사학회지
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• 제37권6_1호
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• pp.1709-1718
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• 2021

항공수심라이다[airborne bathymetric LiDAR (Light Detection And Ranging)] 시스템의 웨이브폼(waveform) 데이터는 기존의 이산반환(discrete-return) 데이터에 비해 정확도, 해상도, 신뢰도가 향상된 데이터를 제공하며, 사용자의 데이터 처리 통제력을 강화하며 반환신호에 대한 추가적인 정보 추출을 가능하게 한다. 웨이브폼 분해(waveform decomposition)는 수면과 해저 반사, 수중산란 및 각종 노이즈가 혼재되어 수신된 웨이브폼으로부터 각각의 에코(echo)를 분리하는 기술로, 지형 포인트 추출을 위해 선행되어야 하는 처리 과정이자 측량 성과를 좌우하는 주요 기술이다. 본 연구에서는 항공수심라이다 원시 데이터로부터의 포인트 추출 성능을 향상시키 위해 새로운 웨이브폼 분해 기술을 개발하였다. 기존의 웨이브폼 분해 기술들이 웨이브폼 피크(peak)들을 가우시안(Gaussian) 분해의 초기값으로 사용하여 분해된 에코의 개수와 분해 성능이 피크 탐지 결과에 좌우되는데 반해, 제안한 기술은 최초 피크들 외에 잠재적인 피크 후보들을 추정하여 추가함으로써, 분해 모델의 근사 정확도를 향상시켰다. 국내 개발된 항공수심라이다 장비인 씨호크(Seahawk)로부터 동해안에서 취득된 웨이브폼 데이터를 이용한 실험 결과, 가우시안 분해 방법 대비 제안한 방법의 모델 근사 적합도(RMSE 기준)가 약 37% 향상된 결과를 얻었다.

• 한국통신학회논문지
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• 제18권5호
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• pp.611-618
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• 1993

디지털 통신 시스템에서는 미리 정해진 모양의 파형을 발생시키는 것이 필수적이다. 이를 위하여 본 논문에서는 방송계 뉴 미디어 시스템인 RDS(Radio Data System)의 부호화기에서 파형 정형의 한 방법으로 메모리의 Look-up 테이블을 이용하여 기존의 아날로그 여파기보다 효율적인 디지털 파형 여파기를 구현하는 한편, 수신단에서는 전송한 데이터가 에러없이 정확히 복원 가능함을 보인다. 디지털 파형 여파기를 구현하기 위하여 파형 여파기의 제어 알고리즘을 설계하고, IC화를 목표로 discrete 소자를 이용하여 구현하였다. 또한 RDS의 송수신단 전송 실험을 통하여 본 논문에서 제안한 디지틀 파형 여파기의 타당성을 입증하였다.

• 디지털콘텐츠학회 논문지
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• 제10권4호
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• pp.605-614
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• 2009

소프트웨어 정의 무선(SDR)은 다양한 무선통신 환경에 유연하게 대처하기 위하여 하나의 공통 하드웨어 플랫폼에 필요로 하는 응용 소프트웨어를 자유롭게 재구성할 수 있는 무선통신 기술이다. 소프트웨어 정의 무선 기술을 구현한 SCA 기반 재구성 가능한 미들웨어 플랫폼 SCARLET의 기능을 검증하기 위해서는 시스템의 각 기능을 관리하고 분석할 수 있는 시스템이 필요하다. 본 논문에서는 SCARLET과 네트워크로 연결되어 관리 및 제어 기능을 할 수 있는 웨이브폼 관리자 구조를 제안하고, 이를 구현한다. 그리고 SCARLET 미들웨어 플랫폼을 사용하는 전체 시스템의 각 기능을 상세하게 제어하여 전체 시스템을 실험함으로써 구현된 웨이브폼 관리자의 성능을 검증한다.