• Title/Summary/Keyword: 입력 포화

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PI-based Containment Control for Multi-agent Systems with Input Saturations (입력 포화가 존재하는 다중 에이전트 시스템을 위한 PI기반의 봉쇄제어)

  • Lim, Young-Hun;Tack, Han-Ho;Kang, Shin-Chul
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.25 no.1
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    • pp.102-107
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    • 2021
  • This paper discusses the containment control problem for multi-agent systems with input saturations. The goal of the containment control is to obtain swarming behavior by driving follower agents into the convex hull which is spanned by multiple leader agents. This paper considers multiple leader agents moving at the same constant speed. Then, to solve the containment problem for moving leaders, we propose a PI-based distributed control algorithm. We next analyze the convergence of follower agents to the desired positions. Specifically, we apply the integral-type Lyapunov function to take into account the saturation nonlinearity. Then, based on Lasalle's Invariance Principle, we show that the asymptotic convergence of error states to zero for any positive constant gains. Finally, numerical examples with the static and moving leaders are provided to validate the theoretical results.

A Design and Implementation of SpO2 Wearable Device for Companion Animals in PPG Signals

  • Kim, Woo-Chan;Chang, Jin-Wook;Kwon, Hoon;Lee, Won Joo;Kwak, Ho-Young
    • Journal of the Korea Society of Computer and Information
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    • v.27 no.11
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    • pp.191-198
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    • 2022
  • The most basic thing to measure the condition of a companion animal is to check the breathing and pulse. There are several methods to measure the breathing and pulse of a companion animal, and the PPG method is generally used to measure the oxygen saturation (SpO2) in a companion animal. However, since the input PPG signal is inputted with various information as well as oxygen saturation, it is necessary to separate and extract oxygen saturation information from the PPG signal in order to measure the oxygen saturation. Therefore, in this paper, a wearable measuring device for companion animals that can be measured by applying the PPG method was designed and implemented, and an algorithm for separating oxygen saturation information from the PPG signal input through the wearable measuring device was proposed.

Modification of TOPMODEL Considering Spatial Connectivity of Saturated Area (공간적 포화면적의 공간적 연결을 고려한 TOPMODEL의 개선과 적용)

  • Kim, Sang-Hyeon;Kim, Gyeong-Hyeon
    • Journal of Korea Water Resources Association
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    • v.32 no.5
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    • pp.515-524
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    • 1999
  • A methodology to resolve a TOPMODEL problem has been suggested, which is associated with the spatial distribution of soil moisture behaviour in a runoff mechanism. A procedure to integrate the spatial information of saturation deficit in the TOPMODEL reflects the connectivity of saturated area in a watershed. The developed algorithm includes an improved basis in tracing the runoff path without increasing the number of parameters. The performance of the developed algorithm has been tested to an upland subwatershed, namely Dongok, which is the IHP watershed located at Wichon, Korea. Comparing with the original statistical version of the TOPMODEL, it has been found that the suggested algorithm can relax an overestimation of peak rate in the runoff simulation.

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A Robust Digital Pre-Distortion Technique in Saturation Region for Non-linear Power Amplifier (비선형 전력 증폭기의 포화영역에서 강인한 디지털 전치왜곡 기법)

  • Hong, Soon-Il;Jeong, Eui-Rim
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.05a
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    • pp.681-684
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    • 2015
  • Power amplifier is an essential component for transmitting signals to a remote receiver in wireless communication systems. Power amplifier is a non-linear device in general, and the nonlinear distortion becomes severer as the output power increases. The nonlinearity results in spectral regrowth, which leads to adjacent channel interference, and decreases the transmit signal quality. To linearize power amplifiers, many techniques have been developed so far. Among the techniques, digital pre-distortion is known as the most cost and performance effective technique. However, the linearization performance falls down abruptly when the power amplifier operates in its saturation region. This is because of the severe nonlinearity. To relieve this problem, this paper proposes a new adaptive predistortion technique. The proposed technique controls the adaptive algorithm based on the power amplifier input level. Specifically, for small signals, the adaptive predistortion algorithm works normally. On the contrary, for large signals, the adaptive algorithm stops until small signals occur again. By doing this, wrong coefficient update by severe nonlinearity can be avoided. Computer simulation results show that the proposed method can improve the linearization performance compared with the conventional digital predistortion algorithms.

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Square Attacks of Reduce-Round in KASUMI (블록암호 KASUMI에 대한 포화공격)

  • 이제상;이태건;이창훈;이원일;홍석희;이상진
    • Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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    • 2003.12a
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    • pp.615-619
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    • 2003
  • 본 논문에서는 5-라운드 KASUMI의 포화공격에 대하여 다룰 것이다. KASUMI는 3GPP에서 사용되는 알고리즘으로, 64비트의 평문을 입력받아 128비트의 키를 사용하여 64비트의 암호문을 출력하는 블록암호이다. 본 논문에서는 l0$\times$2$^{32}$의 선택 평문을 이용하여, 공격 복잡도 2$^{115}$ 를 갖는 5라운드 포화공격(Square Attack)을 소개할 것이다. 또한, 이 공격은 함수의 키를 9비트 고정함으로서 향상시킬 수 있다. 이러한 경우, 7$\times$2$^{32}$ 의 선택평문을 이용하여, 공격 복잡도 2$^{83}$ 을 갖는 5라운드 포화공격을 성공시킬 수 있다.

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Single input source driving of cascaded H-bridge multilevel inverter by using forward converter (포워드 컨버터를 응용한 Cascaded H-Bridge 멀티레벨 인버터의 단일 입력전원 구동)

  • Kim, Sun-Pil;Kang, Feel-Soon
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.1161-1162
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    • 2011
  • 본 논문에서는 독립된 DC 입력전원을 요구하는 Cascaded H-bridge 멀티레벨 인버터를 단일 입력전원으로 구동시키기 위한 회로 구조를 제안한다. 변압기 포화를 방지하기 위해 채용되는 리센 권선을 가지는 포워드 컨버터의 구조를 변경한 것으로 리셋 권선에 의해 전원으로 회생되는 에너지가 출력단으로 전달되도록 변경된다. 제안된 회로 구조의 입출력전압과 스위치의 도통비와의 관계를 이론적으로 분석하고 시뮬레이션을 통해 타당성을 검증한다.

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Surface Saturation Area-Subsurface Outflow-Soil Moisture Storage Relationships: II. Dynamic Analysis (지표포화지역-중간류유출-흙수분저류량 관계: II. 동적 분석)

  • 이도훈;이은태
    • Water for future
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    • v.29 no.2
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    • pp.143-151
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    • 1996
  • The dynamic responses in the subsurface outflow, surface saturation area, soil moisture storage are established by numerical experiments with Richards equation. In addition to this, the dynamical relationship between surface saturation area and subsurface outflow, and between surface saturation area and soil moisture storage are also determined by varying the hillslope shape, soil type, and boundary condition. The simulation results indicate that the dynamical relationships between surface saturation area and subsurface outflow, and between surface saturation area and soil moisture storage are approximated by the steadystate relationships. And the dynamic responses of subsurface outflow and surface saturation area are characterized by the double peaks although the rainfall pattern is asimple pulse input. As a result of numerical simulation, the physical mechanism for the occurrence of the double peaks is explained using the concept of variable source area.

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A Contrast Enhancement algorithm using adaptive threshold in infrared image environment (적외선 영상 환경에서 적응형 임계값을 이용한 동적영역 분할 히스토그램 평활화 기법)

  • Oh, Sun-Mi;Song, Joongseok;Park, Jong-Il
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2014.11a
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    • pp.150-153
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    • 2014
  • 영상 표시 장치에서 대조 이미지의 왜곡 현상을 보완하기 위해 히스토그램 평활화(Histogram Equalization)와 플래토 평활화(Plateau Equalization)가 사용된다. 히스토그램 평활화(Histogram Equalization)를 이용하여 명암대비를 증가 시킬 경우 과도한 이미지의 밝기 변화에 따른 과포화 현상이 발생하며 실시간 시스템에서는 물체 추적에 왜곡 현상이 발생한다. 특히, 적외선 영상(infrared image)과 같이 명암비가 한쪽으로 치우쳐 있는 영상들을 명암비를 개선하기 위해서는 플래토 평활화(Plateau Equalization)와 같은 영상 개선 방법이 필수적이다. 플래토 평활화에서는 임계값을 사용하는 방법이 제시되고 있지만 실험에 의한 최적 임계값을 찾아내는 방식이며, 이 방법은 입력되는 새로운 영상마다 임계값을 실험에 의해 매번 반복해서 도출해야 문제점이 있다. 본 논문에서 제안하는 방법은 과포화 되는 이미지 영역의 문제를 해결하기 위해 제시하는 방법으로 히스토그램 평활화(Histogram Equalization)의 동적 분할하는 알고리즘에 근거하되, 입력 영상에따라 적응적으로 임계값을 설정하는 기법을 제안한다. 실험을 통해 제안하는 방법이 실시간 영상에서 기존의 동적분할 히스토그램에 비해 자연스럽게 명암비를 개선하여 과포화 되거나 중요한 정보를 누락하여 왜곡 되지 않게 자연스러운 화면을 재생하는 방법을 제안한다.

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The effect of gain recovery at the optical fiber amplifier by the input pulse train (광섬유 증폭기에서의 입력 펄스 열에 의한 Cain Recovery 특성)

  • 이재명;이영우
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.3
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    • pp.459-463
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    • 2002
  • We studied the effect of gain recovery at the optical fiber amplifier by the input pulse trains We also theoretically analyzed the limitation of the saturation and recovery time for the PDFA(Praseodymium-Doped Fiber Amplifier) which has the spectral gain at 1.3${\mu}{\textrm}{m}$ band. We can predict the interval between the pulse train, pump power, and the effect of the saturation and recovery time which is affected to the amplification of the optical pulse.

The effect of gain recovery at the optical fiber amplifier by the input pulse train (광섬유 증폭기에서의 입력 펄스 열에 의한 Cain Recovery 특성)

  • 이재명;이영우
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.505-508
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    • 2002
  • We studied the effect of gain recovery at the optical fiber amplifier by the input pulse trains. We also theoretically analyzed the limitation of the saturation and recovery time for the PDFA(Praseodymium-Doped Fiber Amplifier) which has the spectral gain at 1.3${\mu}{\textrm}{m}$ band. We can predict the interval between the pulse train, pump power, and the effect of the saturation and recovery time which is affected to the amplification of the optical pulse.

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