• Title/Summary/Keyword: Offset

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A New Frame Offset Assignment Algorithm For Reducing the Soft Handoff Blocking Probability Due to Lack of Frame Offset Capacity (Frame Offset의 불일치로 인하여 발생하는 Soft Handoff Blockig Probability를 줄이기 위한 새로운 Frame Offset Assignment Algorithm)

    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.9B
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    • pp.1624-1630
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    • 1999
  • Code division multiple access (CDMA) is a promising air interface technique for cellular systems. When an MS (Mobile Station) moves to an adjacent cell, the handoff between the serving cell and the target cell is needed. Compared with the hard handoffs, the soft handoffs between two CDMA channels with the identical frequency assignments and frame offsets can provide a better quality of service by minimizing the undesirable ping pong phenomenon of back-and forth handoffs between two adjacent cells in conventional hard handoffs. For the soft handoff of a call to an adjacent cell to be successful, the adjacent cell should assign to the call the same frame offset as that being used in the original cell by the call. In this paper, considering the assignment states of the frame offsets of the adjacent cells, a frame offset assignment algorithm for the originated call is proposed. And analytic method for the handoff blocking probability due to the lack of the frame offset capacity is also presented to show the advantage of the proposed algorithm with respect to the soft handoff blocking probability.

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Analysis of the Effect on Offset Time under Fault and Propose a New Restoration Scheme Considering QoS in OBS Networks (광 버스트 스위칭 망에서 망 고장에 대한 offset 시간 영향 분석 및 QoS를 고려한 장애 복구 기법)

  • 이해정;송규엽;소원호;김영천
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.12
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    • pp.94-105
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    • 2003
  • OBS(Optical Burst Switching) networks which decouple the burst from its header has characteristic one-way reservation. Therefore, the fault of a fiber link may lead to the magnitude of burst loss. Since sending a header packet and using an offset time before the transmission of the corresponding burst. In this paper, we analysis a offset time based on the burst loss rate resulting from only link failure and by applying the restoration schemes in an optical burst switching networks. The simulation results in terms of the effect of a offset time is evaluated in our network model to verify that comparing the numerical analysis with simulation result. Finally, and through these results, We propose the new restoration scheme based on offset time considered Quality of Service.

Adaptive offset decision of current sensor (적응형 전류센서 offset 보정량 검출)

  • Lee, Yoon-Hyung;Han, Sang-Whi
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.438-440
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    • 2012
  • 본 논문은 EPS ECU 에 사용되고 있는 전류센서의 offset 결정에 대해 효율적인 방법을 제시한다. 센서의 offset 은 EPS 시스템에서 모터의 토크리플을 야기하기 하므로, 토크리플을 줄이기 위해 offset 을 보정하여 모터를 제어하게 된다. 일반적으로 EPS ECU 에 대해 offset 보정 방법은 ECU 생산시 센서의 offset 값을 측정하여 EEPROM 에 기록하고, 모터 제어시 활용한다. 이러한 방식은 ECU 생산의 cycle time 을 늘릴 뿐만 아니라, 센서 및 주변 회로의 노후로 인해 MCU 의 입력으로 들어오는 offset 값의 변화에 대해 대응할 수 없는 한계를 가진다. 언급된 문제를 보완하기 위해 본 논문은 ECU 생산시 offset 을 EEPROM 에 기록하는 것이 아니라 ECU 가 ON 때마다 센싱값을 정확하게 취득하여 offset 값을 선정하고 '강인한 오차 기준' 함수를 사용하여 노이즈의 영향을 줄이는 방법을 제시한다.

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An offset algorithm with forward tracing of tangential circle for open and closed poly-line segment sequence curve (접원의 전방향 경로이동에 의한 오프셋 알고리즘)

  • Yun, Seong-Yong;Kim, Il-Hwan
    • Proceedings of the KIEE Conference
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    • pp.1022-1030
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    • 2003
  • In this paper we propose a efficient offset curve construction algorithm for $C^0$-continuous Open and Closed 2D sequence curve with line segment in the plane. One of the most difficult problems of offset construction is the loop problem caused by the interference of offset curve segments. Prior work[1-10] eliminates the formation of local self-intersection loop before constructing a intermediate(or raw) offset curve, whereas the global self-intersection loop are detected and removed explicitly(such as a sweep algorithm[13]) after constructing a intermediate offset curve. we propose an algorithm which removes global as well as local intersection loop without making a intermediate offset curve by forward tracing of tangential circle. Offset of both open and closed poly-line segment sequence curve in the plane constructs using the proposed approach.

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A Study on the Power Comparison between Logistic Regression and Offset Poisson Regression for Binary Data

  • Kim, Dae-Youb;Park, Heung-Sun
    • Communications for Statistical Applications and Methods
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    • v.19 no.4
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    • pp.537-546
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    • 2012
  • In this paper, for analyzing binary data, Poisson regression with offset and logistic regression are compared with respect to the power via simulations. Poisson distribution can be used as an approximation of binomial distribution when n is large and p is small; however, we investigate if the same conditions can be held for the power of significant tests between logistic regression and offset poisson regression. The result is that when offset size is large for rare events offset poisson regression has a similar power to logistic regression, but it has an acceptable power even with a moderate prevalence rate. However, with a small offset size (< 10), offset poisson regression should be used with caution for rare events or common events. These results would be good guidelines for users who want to use offset poisson regression models for binary data.

The Analysis of I-V characteristics on n-channel offset gated poly-Si TFT`s (Offset 구조를 갖는 n-채널 다결정 실리콘 박막 트랜지스터의 I-V 분석)

  • 변문기;이제혁;김동진;조동희;김영호
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.26-29
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    • 1999
  • The I-V characteristics of the n-channel offset gated poly-Si TETs have been systematically investigated in order to analyse the effects of offset region. The on currents are reduced due to the series resistance by the offset length and there is no kink phenomenon in offset devices. The off currents of the offset gated TFTs are remarkably reduced to 10$^{-12}$ A independent of gate and drain voltage because the electric field is weakened by the increase of the depletion region width near the drain region. It is shown that the offset regions behave as a series resistance and reduce lateral and vertical electric field.

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A robust frequency offset estimation scheme for an OFDM system (OFDM 수신기를 위한 강인한 주파수 옵셋 보정 기법)

  • Wui, Jung-Hwa;Hwang, Hu-Mor;Song, Jin-Ho
    • Proceedings of the KIEE Conference
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    • pp.3100-3102
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    • 2000
  • In this paper, we propose to a robust frequency offset estimation method of OFDM signals. A carrier frequency offset may be decomposed into an integer multiple of the subcarrier spacing and a residual frequency offset. Fractional part of frequency offset is obtained by using the maximum likelihood estimation(MLE) method. And we use the correlation of the samples at the output of the discrete Fourier transform(DFT) to estimate integer part of frequency offset. The result shows that the estimation frequency offset is almost linear to frequency offset. We propose to an improved estimation error variance of the carrier frequency offset estimation. The proposed estimator has better performance than the conventional ones in terms of error variance and tracking range.

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A Study on Efficient Frequency Offset Compensation Method for OFDM based WiBro Systems (OFDM 기반의 WiBro 시스템에서 효과적인 주파수 오프셋 보상 기법에 관한 연구)

  • Kim, Eun-Cheol;Ha, Kwang-Jun;Park, Jae-Sung;Kim, Jin-Young
    • 한국정보통신설비학회:학술대회논문집
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    • pp.437-440
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    • 2008
  • In this paper, we present and analyze a robust frequency offset estimation scheme for orthogonal frequency division multiplexing (OFDM) systems over radio communication channels. When there exists frequency offset, the loss of orthogonality occurs and the interference problem among several subcarriers in OFDM signals is introduced. The guard interval of OFDM signals is employed for estimating the frequency offset. Furthermore, in order to enhance the frequency offset estimation performance, a ternary sequence is utilized. A frequency offset is estimated based on the synchronized correlator output. The proposed frequency offset estimation scheme can be applied to track the carrier frequency offset of OFDM systems.

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A New Offset Algorithm for Closed 2D Lines with Islands (섬을 가진 2차원 직선 폐곡선에 대한 새로운 오프셋 알고리듬)

  • Kim Hyun-Chul;Lee Sung-Gun;Yang Min-Yang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.2
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    • pp.141-148
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    • 2006
  • In this paper, a new offset algorithm for closed 2D lines with islands is introduced and the result is illustrated. The main point of the proposed algorithm is that every point is set to be an offset by using bisectors, and then invalid offset lines, which are not to be participated in offsets, are detected in advance and handled with an invalid offset edge handling algorithm. As a result, raw offset lines without local invalid loops are generated. The proposed offset method is proved to be robust and simple, moreover, has a near O(n) time complexity, where n denotes the number of input lines. In addition, the proposed algorithm has been implemented and tested with 2D lines of various shapes.

Output Current DC offset Removal Method for Trans-less PV Inverter (무변압기형 태양광 인버터의 출력 전류 DC offset 제거 방법)

  • Hong, Ki-Nam;Choy, Ick;Choi, Ju-Yeop;Lee, Sang-Chul;Lee, Dong-Ha
    • Journal of the Korean Solar Energy Society
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    • v.32 no.spc3
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    • pp.255-261
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    • 2012
  • Since PV PCS uses output current sensor for ac output current control, the sensor's sensing value includes unnecessary offset inevitably. If PV inverter is controlled by the included offset value, it's output current will generate DC offset. The DC offset of output current for trans-less PV inverter is fatal to grid, which results in saturating grid side transformer. Usually DSP controller of PV inverter reads several times sensing value during initial operation and, finally, it's average value is used for offset calibration. However, if temperature changes, the offset changes, too. And also, the switch device is not ideal, both each switching element of the voltage drop difference and on & off time delay difference generate DC offset. Thus, to compensate for deadtime and the switch voltage drop, feedback control by output current DC offset should be provided to compensate additional distortion of the output current. The validity of the proposed method is confirmed through PSIM simulation.