• Title/Summary/Keyword: Offsets

검색결과 341건 처리시간 0.03초

A Study on the Bandwidth Efficient Self-Cancellation Scheme of Interchannel Interference (ICI) For OFDM Transmission Systems

  • Kim, Gi-Rae;Chung, Yeon-Do
    • Journal of information and communication convergence engineering
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    • 제4권4호
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    • pp.162-165
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    • 2006
  • This paper presents a bandwidth efficient self-cancellation scheme for interchannel interference (ICI) in OFDM transmission systems. Conventional self-cancellation schemes provide an excellent cancellation capability of ICI for relatively low frequency offsets. However, this capability is achieved at the expense of bandwidth efficiency and thus a higher modulation level is often used to compensate for desired throughput. By applying a partial differential coding (PDC) to the transmit data prior to the ICI self-cancellation, bandwidth efficiency is greatly improved by a factor of 2, while maintaining a string of data (+1, -1) alternately for the ICI. self-cancellation in OFDM systems. Computer simulations show that the performance of the proposed scheme is comparable to the conventional self-cancellation scheme with slight performance degradation for relatively lower frequency offsets.

Study on the Clearance Design for Low Side Impacts of Engine Piston

  • Cho, Joon-Haeng;Jang, Si-Youl
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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    • pp.427-428
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    • 2002
  • Clearance movements of engine piston are regarded very important because they cause impact vibrations as well as many tribological problems. Some of the major parameters that influence these kinds of performances are piston profiles, piston offsets and clearance magnitudes. In our study. computational investigation is performed about the piston movements in the clearance between piston and cylinder liner by changing the skirt profiles and piston offsets. Our results show that curved profile and more offset to thrust side have better performance with low side impact during the engine cycle.

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윤곽 가공을 위한 삼각 스플라인을 이용한 오프셋 곡선의 생성 (Offsetting Curves Using Trigonometric Splines for Contour Cutting)

  • 고구용;윤재득;정융호
    • 한국CDE학회논문집
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    • 제15권4호
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    • pp.253-260
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    • 2010
  • This paper presents algorithms for computing offsets of freeform curves. The approach first divides the original curve into several segments at the inflexion points. Based on the obtained new control polygon and its offsets, quadratic trigonometric splines are constructed to approximate the offset curves. Finally, the shape parameter value of trigonometric spline is determined to satisfy the required tolerance. The degree of the output curve is two, independent of the original curve's degree. Because of the great controllability, the proposed method can generate a completely overestimating offset curve by adjusting the value of the shape parameter, which guarantees no overcutting in NC machining. Furthermore, it also produces the lowest number of control points compared with other works.

다중채널 직접구동 엑츄에이터의 구동전류 동일화 루프 설계 (Current Equation Loop Design of Muti-channel Direct Drive Valve Actuation)

  • 남윤수
    • 한국정밀공학회지
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    • 제17권10호
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    • pp.162-169
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    • 2000
  • A Direct Drive Valve(DDV) hydraulic actuation system which is commonly used as an aircraft's control surface driving actuator has multi-loop control structure to ensure its safety operation. However, because of not perfect matching of one self channel characteristics with the others, the servo valve driving current of each channel can be widely different. Therefore, the long-time use of DDV actuator without any correction of these channel current offsets will cause the problem of performance or life expectancy degradation due to unwanted heats in the linear motor. A current equalization loop structure which can minimizes current offsets between channels is introduced and designed. The performance of the current equalization loop is investigated and verified through the analytic and experimental ways.

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교차로 방향별 차선공동이용 연구

  • 김동녕
    • 대한교통학회지
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    • 제6권2호
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    • pp.49-56
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    • 1988
  • Alternate use of lane at a signalized intersection is a quite different control of the operation of an intersection. This control introduces a new stop line and signal before the original stop line. All of the lanes between the two stop lines are used for left turn traffic or through traffic at a time. The purpose of the control is increasing the capacity of a n intersection without widening the approach width. this paper contains a study on the condition of a application, the proper distances between the two stop lines, the reasonable offsets(rear) to guarantee clearing the vehicles of previous phase, the comparison of approach capacity between the existing control and this control. The study results reveals that the offsets(rear) are rather stable showing the range(maximum value minus minimum value) of it's value does not exceed 3.6 seconds according to the field data. The approach capacity will be increased by 27%, 43%, 59%, 84% when the distances between the stop lines are 30.0m respectively. The control might have theoretical limitation to operate in practice. So an experimental application of the control at some suitable intersections prior to expanding it.

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곡면 모델링에서 3차원 경계 곡면 블렌드 구성에 관한 연구 (A Study on The Construction of 3-Dimensional Edge Blend Surface Modeling)

  • 이창억
    • 기술사
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    • 제27권3호
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    • pp.121-131
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    • 1994
  • 3차원 자유 형상 곡면으로 이루어진 선형을 부분적으로 표현하기란 매우 힘들다. 선박 설계에 컴퓨터를 이용한 기술이 적용되기 시작하면서, 기하학적 모델링 기법이 개발되어 왔다. 선형 모델링에서,곡률 변화가 심한 선체 곡면의 국부적인 곡면 형상을 Blending 기법을 써서 표현하는 연구는 이루어지지 않았다. Blend곡면을 써서, 설계시에 도면상에 표시되는 작은 곡면을 부드럽게 표현하는 방법을, 선체표면과 돌출된 접합 부분을 Blending 하고져 하였다. 본 연구에서는, 두개의 Base곡면에 Blend반지름을 입력 했을 때, Blend곡면에 Blending방법을 이용하여 공간 좌표인 Offsets 데이터를 얻을 수 있도록 선박 설계에 적용하여 보았다.

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AUTOMATIC GAIN AND PHASE COMPENSATION IN RTU

  • Pin Jiang;Ping Jiang;Wang, Wen-Rong;Ma, Cun-Hua
    • 한국시뮬레이션학회:학술대회논문집
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    • 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
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    • pp.325-328
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    • 2001
  • This paper introduces a new technique to extract eigenvalues of the gain and phase offsets and to compensate them automatically in transducerless sampling RTU. It discusses in detail the cause of the offsets, describes the principles of gain and phase compensation, establishes the algorithm to extract eigenvalues. The process of using the compensated measurements is also illustrated in the paper. This technique enhances the operational speed, simplifies the operational complexity, and improves the capability of transducerless sampling in RTU.

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지반공학에서 레이저센서의 활용 (Application of Laser Sensor to Geotechnical Engineering)

  • 박봉근;남문석;최용규
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2007년 가을학술발표회
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    • pp.440-449
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    • 2007
  • Recently, researches for side resistances of drilled shafts considering socket roughness have been conducted actively. In order for these researches, roughness measurement devices using laser sensor were developed by two research groups. The devices were only applied in boreholes with dry conditions. In this research, a roughness measurement devices using the laser sensor (BKS-LRPS) was developed, which could apply in wet conditions and also measure vertical offsets of drilled shafts. In addition, the application of the laser sensor to the geotechnical engineering proposed in this paper.

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