• 제목/요약/키워드: synchronization problem

검색결과 324건 처리시간 0.028초

The Analysis of tight Coupling and Propagation for a Composite Fiber-Dielectric Slab with a Conductor Cladding

  • Kwon, Kwang-Hee;Song, Jae-Won;Kim, Jeong-Hoon;Park, Euy-Don;Son, Seok-Woo
    • Journal of the Optical Society of Korea
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    • 제7권1호
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    • pp.20-27
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    • 2003
  • A theoretical presentation of evanescent coupling is offered with respect to the refractive indexes between a side-polished optical fiber and an infinitely planar waveguide with a conductor cladding (PWGCC). The PWG is suspended at a constant distance from an unclad fiber core and attached with the perfect conductor (PEC) on one side. The behavior of the distributed couple. is examined using a coupled mode model, which takes account of the two dimensions of the waveguide configuration. The coupling and propagation of light were found to depend on both the relationship between the refractive index values of each structure and the configuration of the side-polished fiber used in the PWGCC. The spreading of light in the unconfined direction of the PWGCC is described in terms of a simple geometrical interpretation of the synchronization condition that is in agreement with a previous investigation of the problem based on the coupled-mode theory (CMT). The power of the light propagation in the fiber decreased exponentially along the fiber axis as it was transferred to the PWGCC, where it was carried away.

순시전력 합성 개념을 이용한 가상주파수 3상 실효전압 계측기법 (3-Phase RMS Voltage Measurement Method of Virtual Frequence using Instantaneous Power Component Concept)

  • 박성미;양지훈;박성준
    • 한국산업융합학회 논문집
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    • 제22권3호
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    • pp.251-257
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    • 2019
  • This paper proposes a new measurement method using virtual power concept to measure the effective value of 3-phase voltage with variable frequency. The conventional effective value measurement method uses a method of integrating data sampled during one or half cycle of the power voltage and averaging it. In this method, since the effective voltage is calculated every cycle, a time delay occurs in the measured effective voltage and it is s a problem to measure the effective value of a device whose frequency varies from time to time, such as a generator. The proposed 3-phase voltage rms measurement method has an advantage that it can measure accurate voltage RMS value regardless of measurement frequency variation. In particular, there is an advantage in that it is possible to measure a 3-phase effective voltage rather than an average value of the effective voltage of each phase in a 3-phase unbalance voltage. In addition, the validity of the proposed method is verified by using the Psim simulation tool and the experimental results are analyzed by applying the proposed measurement algorithm to the actual three phase synchronous generator voltage measurement experiment.

프라이버시와 완전한 전방향 안전성을 제공하는 UMTS 키 동의 프로토콜 (A UMTS Key Agreement Protocol Providing Privacy and Perfect Forward Secrecy)

  • 김대영;최용강;김상진;오희국
    • 정보보호학회논문지
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    • 제17권3호
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    • pp.81-90
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    • 2007
  • 3G 이동 통신 기술 중 하나인 UMTS(Universal Mobile Telecommunications System)에서는 무선 구간의 안전한 통신을 위해 UMTS AKA(Authentication and Key Agreement) 프로토콜을 사용한다. 그러나 이 프로토콜은 SN(Serving Network)과 HN(Home Network)의 네트워크 대역폭 소모 문제, SQN(SeQuence Number) 동기화 문제 등 여러 가지 문제점이 제기되었다. 본 논문에서는 UMTS AKA 프로토콜의 문제점을 개선한 새로운 타원곡선 기반 UMTS AKA 프로토콜을 제안한다. 제안하는 프로토콜은 IMSI(International Mobile Subscriber Identity)의 노출로 인한 문제점으로부터 프라이버시 보호를 강화하고, ECDH(Elliptic Curve Diffie Hellman) 기법을 통해 완전한 전방향 안전성을 제공한다.

저비용 RFID 시스템에 적합한 효율적인 인증 방법 (Efficient Authentication Protocol for Low-Cost RFID System)

  • 김진호;서재우;이필중
    • 정보보호학회논문지
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    • 제18권2호
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    • pp.117-128
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    • 2008
  • RFID 시스템은 동시에 여러 개의 개체를 인식할 수 있는 장점을 바탕으로 기존의 광학 바코드 시스템을 대체할 새로운 기술로 주목받고 있다. 하지만 RFID 시스템을 이루는 태그와 리더 사이의 통신은 RF 신호를 이용하기 때문에 공격자에게 쉽게 노출될 수 있고, 그로 인해 여러 가지 보안위협이 존재한다. 이런 위협을 해결하기 위해서 많은 연구 활동이 있었다. 본 논문에서는 기존 연구를 기반으로 RFID 인증 프로토콜을 동기 필요의 유무에 따라 상태기반과 비 상태기반 인증 모델로 나누어 설명한다. 그리고 Bloom filter를 이용해서 백엔드 데이터베이스에서의 인증 시간을 단축하는 방법을 제안한다. 이는 상태기반과 비 상태기반 모두에 적용가능하며, RFID 인증에서 발생할 수 있는 태그 검색 문제를 해결하는 새로운 접근이다.

머신비전을 위한 LED 조명시스템의 스트로브 제어 구동에 관한 연구 (A Study on Strobe Control over LED Lighting System for Machine Vision)

  • 김태화;이천
    • 한국전기전자재료학회논문지
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    • 제34권2호
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    • pp.121-125
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    • 2021
  • The machine vision technology has been widely used in the industrialized nations like the United States, Japan, and EU in the various industries from the late 1980s. Machine vision inspection system mainly consists of a camera, optics, illumination and an image acquisition system. Optimization of the illumination light source is very important. This paper shows a comparison between Pulse Width Modulation (PWM) control and strobe control in driving LED lighting system for machine vision. PWM control method has problems such as a temperature rising of LED and a flickering in image measurement for inspection. In contrast, the proposed strobe control method can suppress the temperature of LED light source below 40℃. Also, it can remove the flickering problem through a synchronization between a frame grabber and a camera shutter. Finally, the strobe control method was shown to extract clearer images with a high precision compared to PWM control method.

Design of Orbit Simulation Tool for Lunar Navigation Satellite System

  • Hojoon Jeong;Jaeuk Park;Junwon Song;Minjae Kang;Changdon Kee
    • Journal of Positioning, Navigation, and Timing
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    • 제12권4호
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    • pp.335-342
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    • 2023
  • Lunar Navigation Satellite System refers to a constellation of satellite providing PNT services on the moon. LNSS consists of main satellite and navigation satellites. Navigation satellites orbiting around the moon and a main satellite moves the area between the moon and the L2 point. The navigation satellite performs the same role as the Earth's GNSS satellite, and the main satellite communicates with the Earth for time synchronization. Due to the effect of the non-uniform shape of the moon, it is necessary to focus on the influence of the lunar gravitational field when designing the orbit simulation for navigation satellite. Since the main satellite is farther away from the moon than the navigation satellite, both the earth's gravity and the moon's gravity must be considered simultaneously when designing the orbit simulation for main satellite. Therefore, the main satellite orbit simulation must be designed through the three-body problem between the Earth, the moon, and the main satellite. In this paper, the orbit simulation tool for main satellite and navigation satellite required for LNSS was designed. The orbit simulation considers the environment characteristics of the moon. As a result of comparing long-term data (180 days) with the commercial program GMAT, it was confirmed that there was an error of about 1 m.

Development of a Real-time Error-detection System;The Case study of an Electronic Jacquard

  • Huh, Jae-Yeong;Seo, Chang-Jun
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2003년도 ICCAS
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    • pp.2588-2593
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    • 2003
  • Any system has the possibility of an error occurrence. Even if trivial errors were occurred, the original system would be fatally affected by the occurring errors. Accordingly, the error detection must be demanded. In this paper, we developed a real-time error detection system would be able to apply to an electronic Jacquard system. A Jacquard is a machine, which controls warps while weaving textiles, for manufacturing patterned cloth. There are two types of mechanical and electronic Jacquard. An electronic Jacquard is better than a mechanical Jacquard in view of the productivity and realizability for weaving various cloths. Recent weaving industry is growing up increasingly due to the electronic Jacquard. But, the problem of wrong weaving from error data exists in the electronic Jacquard. In this research, a real-time error detection system for an electronic Jacquard is developed for detecting errors in an electronic Jacquard in real-time. The real-time system is constructed using PC-based embedded system architecture. The system detects the occurring errors in real-time by storing 1344 data transferred in serial from an electronic Jacquard into memory, and then by comparing synchronously 1344 data stored into memory with 1344 data in a design file before the next data would be transferred to the Jacquard for weaving. The information of detected errors are monitored to the screen and stored into a file in real-time as the outputs of the system. In this research, we solve the problem of wrong weaving through checking the weaving data and detecting the occurred errors of an electronic Jacquard in real-time.

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학습동기가 시험 스트레스와 스트레스 대처 양식에 미치는 영향 (Effects of Learning Motivation on the Stress Coping Style and Stress of Test)

  • 장철;이은혜;천지수
    • 대한통합의학회지
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    • 제2권2호
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    • pp.89-96
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    • 2014
  • Purpose : In this study, we selected three research subjects to attempt to clear learning motivation of college students is what impact the stress coping style and stress test. First, age, gender, the future career after graduation, the presence or absence of part-time job is, its impact on learning motivation. Second, learning motivation is what effect the stress of the test. Third, based on the motivation of learning, how deal pursuing efforts form the social support, the center of the problem-solving approach, seeking to avoid the reaction to stress how different form. Methods : K University occupational therapy and one, two, three grade 100 students (male 22 people, female 78) to target age, sex, and after graduation, part-time status, motivation, stress, stress coping style questionnaire for distribution and was written. Results : First of all, women's social support form graduation course, more robust than pursue blank after the synchronization uncertainty and stress, and graduated from the trading center and avoid the use of career, more form. Second, motivation and stress test, a difference between the notice could not see. Third, the higher the motivation of learning, problem-solving, Action form to the center to use as many as you, but avoid using too much in the center form is addressed. Conclusion : As a result of the study that came out of the course after graduating from ensure that learning motivation is high, the more the uncertainty, the more to cope with stress in the center of the form to avoid form address was used. Because of this, the student careers after graduation, to make sure that can help you to compare efforts over is believed to be necessary.

폭주회피를 위한 큐 관리 기반의 패킷 탈락 알고리즘 (A Packet Dropping Algorithm based on Queue Management for Congestion Avoidance)

  • 이팔진;양진영
    • 인터넷정보학회논문지
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    • 제3권6호
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    • pp.43-51
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    • 2002
  • 본 논문은 능동적인 큐 관리를 이용한 새로운 패킷 탈락 알고리즘에 대해 연구이다. 능동적인 큐 관리 기법은 기존의 Drop Tail과 다른데, Drop Toil은 버퍼 오버플로우가 발생하면 패킷 탈락되는 반면, 능동적인 큐 관리 기법인 RED는 폭주가 발생하기 전에 패킷이 탈락된다는 것이다. 그러나 능동적인 큐 관리 기법은 버퍼 크기가 충분히 크지 않을 때 높은 패킷 손실률을 초래한다. 폭주를 탐지하고 무작위로 선택된 연결에 이를 통보함에 의한 글로벌 동기화와 공정성 문제를 야기하며, 최적의 평균 큐 길이를 찾기 위해서는 네트워크 트래픽 특성이 미리 알려져야 한다는 커다란 문제가 있다. 본 논문에서는 폭주제어를 위한 새로운 큐 관리 기법 기반의 효율적인 패킷 탈락 기법을 제안한다. 제안된 기법은 플로우별 도착률과 추정된 공정한 대역을 사용한다. 이를 이용하여 플로우 도착률과 링크 대역을 계산하기 위한 추정 알고리즘을 제안한다. 제안된 기법은 패킷 손실을 가져오는 패킷에 의한 큐 길이의 급속한 진동을 초래하지 않기 때문에 네트워크 성능을 향상시킬 수 있음을 보인다.

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캐릭터 동작 애니메이션 제어를 위한 에이전트 시스템 (An Agent-based System for Character Motion Animation Control)

  • 김기현;김상욱
    • 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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    • 제7권5호
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    • pp.467-474
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    • 2001
  • 사용자가 하나의 캐릭터 이상을 애니메이션 하기를 원할때 캐릭터들 사이에 충돌과 같은 기대되지 않은 동작 애니메이션을 생성할 수 있다. 그러므로, 이러한 문제가 적절한 제어 메커니즘을 이용하여 해결되어야 한다. 본 논문은 사용자의 의도를 반영한 애니메이션 시나리오를 표현하기 위해 캐릭터의 동작 애니메이션을 제어하는 에이전트 기반 시스템을 제안한다. 이 시스템은 3차원 공간상에서 캐릭터가 움직이는 경로에 따라 캐릭터들간의 충돌을 회피하고 동작의 형태를 조정하는 방법을 제공한다. 에이전트는 동작을 동기화하기 위해 다른 에이전트와 통신한다. 에이전트는 캐릭터의 동작을 조정하는 여러 지능적인 에이전트로 확장되어진다. 에이전트 시스템은 의도된 동작 애니메이션 뿐만 아니라 전체 캐릭터 애니메이션에 대한 동작의 스케쥴링을 가능하게 한다. 에이전트들의 정보를 전달하고 에이전트들의 현 상태를 추론하는 방법으로써 에이전트의 대화를 위한 페트리넷 분석을 이용하여 오토마타 모델을 디자인한다. 에이전트 기술을 이용하여 캐릭터의 동작을 제어하기 위한 에이전트 시스템을 구현한다. 인체 모델 캐릭터의 동작을 제어하는 예를 보이고, 동작 제어의 가능성을 보인다.

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