• Title/Summary/Keyword: Timing Analysis

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Performance Analysis of OFDM Timing Synchronization Method with Imperfect Noise Estimation (불완전한 잡음 예측하에서 OFDM 시간 동기화 기법의 성능 분석)

  • Lee, Ki-Chang;Yoon, Young-Joong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.3C
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    • pp.189-194
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    • 2007
  • This paper derives and computes the detection probability of timing synchronization in an orthogonal frequency division multiplexing (OFDM) system encountered with a multipath Rayleigh fading channel and imperfect noise estimation. The timing synchronization scheme using a simple repeated constant amplitude zero auto-correlation (CAZAC) training symbol and correlation techniques is adopted. With this provision, we focus on the numerical analysis for OFDM timing synchronization scheme employing a preadvancement technique to reduce the inter-symbol interference (ISI). For measuring system performance, the detection performance derived in the considered system is presented in a multipath Rayleigh fading channel.

A Study on Loyalty Program for Building Customer Loyalty of Fashion Firm (패션업체 고객 충성도 구축을 위한 로열티 프로그램)

  • Ju, Seong-Rae;Yoo, Myung-Iee
    • Journal of the Korean Society of Clothing and Textiles
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    • v.33 no.2
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    • pp.331-342
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    • 2009
  • The purposes of this study were to provide the apparel companies with a effective marketing strategy by identifying the present condition of loyalty programs and designing the type of reward and the timing of reward, and to investigate the effects of loyalty programs on customers' satisfaction and loyalty. The experimental study was conducted to examine the relationship between loyalty programs and performances. The experiment, which adopted a scenario methodology, was a 2(type of rewards)${\times}$2(timing of rewards) between subjects factorial design. The sample was based on 362 college students. The data analysis was completed on the basis of SPSS 12.0 package, using descriptive analysis, frequency, factor analysis, Cronbach's a, ANOVA, and regression analysis. The following results were found in this research. First the respondent's recognition of reward(benefit, reserve fund, experience) was not relatively high. Second, the interaction effect of type of rewards and timing of rewards on the loyalty programs' satisfaction(p<.01) and customer loyalty(p<.001) was significant, but that on customer satisfaction was not significant. Finally, loyalty programs' satisfaction positively affected customer satisfaction and loyalty. The implications of the research and directions for future researchers were discussed.

The Determinants of the Export Timing and Export Performance of Venture Firms. (국내 벤처기업 수출시기와 수출성과 결정요인에 관한 연구)

  • Park, Keun-Ho;Rowe, Sung-Jae;Lim, Hyo-Chang
    • International Commerce and Information Review
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    • v.9 no.4
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    • pp.41-66
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    • 2007
  • This paper develops a model of the export timing and export performance of venture firms by drawing by resource based view and born-global firm theory. The model aims at explaining the role of internal resources of small new venture firms and environment factors in accelerating the firm's export timing and achieving export growth. Hypothesses were developed around the following factors: management characteristics in terms of CEO's foreign experience and export commitment; organizational characteristics in terms of technological competence and marketing competence, and inter-functional cooperation; and finally environmental factors in terms of domestic and market attractiveness and foreign market attractiveness influence both the export timing and export performance. Structural equation modeling analysis by using 214 small new ventures provides a partial supports for the hypotheses. The result showed that technological competence have an influence on early export timing and that CEO's foreign experience and export commitment, technological competence and foreign market attractiveness are related export performance significantly. It also showed the significant relationship between export timing and export performance.

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Timing Recovery Algorithm with Slop Compensated for Multi-level PAM Signals (Multi-level PAM신호에 적용 가능한 기울기 보상 심볼타이밍 알고리즘)

  • 전광호;임명섭
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.11A
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    • pp.1864-1871
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    • 2001
  • In this paper, new symbol timing recovery algorithm is proposed, which is suitable for the digital communication system with Multi-level PAM signals. In the newly proposed symbol timing recovery algorithm, the timing error function is derived by compensating the several difference values between sampled symbol and neighboring symbol every symbol period with mid samples and decided symbol values. Conventional symbol timing recovery methods did not work well in Multi-level PAM signals, but the newly proposed method can be applied to Multi-level PAM signals as well as QPSK. For the performance analysis, the derived variance of the timing error function and the timing error characteristics of S-curve show that the proposed method has better performance than Gardner method and the modified Gardner method.

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Throughput Analysis of ETSI BRAN HIPERLAN/2 MAC Protocol Taking Guard Timing Spaces into Consideration

  • Ko, You-Chang;Son, Yong-Tae;Shin, Yong-Eok;Lee, Hyong-Woo;Cho, Choong-Ho
    • Proceedings of the Korean Information Science Society Conference
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    • 2003.04d
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    • pp.515-517
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    • 2003
  • In this paper we examine the effects of the required portions of guard timing spaces in a MAC frame of ETSI BRAN HIPERLAN/2 system such as inter-mobile guard timing space in UL(Up Link) duration, inter-RCH(Random CHannel) guard timing space, sector switch guard timing space. In particular, we calculate the number of OFDM(Orthogonal Frequency Division Multiplexing) symbols required for these guard timing spaces in a MAC frame. We them evaluate the throughput of HIPERLAN/2 system as we vary parameter such as the guard time values defined in [2], the number of DLCCs(Data Link Control Connections), and the number of RCHs. Finally we show by numerical results that the portions for the 새심 summation of required guard timing spaces in a MAC frame are not negligible, and that they should be properly considered when trying to evaluate the performance of MAC protocol of HIPERLAN/2 system and also when determining the number of RCHs as well as the number of DLCCs in UL PDU trains at an AP/CC(Access Point/Central Controller).

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A Numerical Analysis for Fuel Consumption by Improvement of Intake/Exhaust Valve Timing in a Common Rail Diesel Engine for a Generator (커먼레일 디젤엔진의 흡배기밸브 타이밍 개선을 통한 연비절감에 대한 수치해석적 연구)

  • Kim, Seung Chul;Kim, Chung Kyun
    • Journal of Energy Engineering
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    • v.26 no.2
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    • pp.32-38
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    • 2017
  • The common rail diesel engine used in this study uses mechanically driven camshaft for the operation of intake and exhaust valves, and the timing of valve opening and closing is fixed according to the operating conditions of the vehicle. However, the electric generator engine operates at a constant speed and partial load. Therefore, in order to optimize the design of common rail diesel engine for power generation, the characteristics of diesel combustion and emissions according to the change of valve timing were examined and calculated in terms of fuel economy. The valve timing of the diesel engine influenced the combustion characteristics by changing the intake and exhaust flow and it was considered that the fuel efficiency of the generator could be improved.

Fine Grain Real-Time Code Scheduling Using an Adaptive Genetic Algorithm (적합 유전자 알고리즘을 이용한 실시간 코드 스케쥴링)

  • Chung, Tai-Myoung
    • The Transactions of the Korea Information Processing Society
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    • v.4 no.6
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    • pp.1481-1494
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    • 1997
  • In hard real-time systems, a timing fault may yield catastrophic results. Dynamic scheduling provides the flexibility to compensate for unexpected events at runtime; however, scheduling overhead at runtime is relatively large, constraining both the accuracy of the timing and the complexity of the scheduling analysis. In contrast, static scheduling need not have any runtime overhead. Thus, it has the potential to guarantee the precise time at which each instruction implementing a control action will execute. This paper presents a new approach to the problem of analyzing high-level language code, augmented by arbitrary before and after timing constraints, to provide a valid static schedule. Our technique is based on instruction-level complier code scheduling and timing analysis, and can ensure the timing of control operations to within a single instruction clock cycle. Because the search space for a valid static schedule is very large, a novel adaptive genetic search algorithm was developed.

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Timing Jitter Analysis and Improvement Method using Single-Shot LiDAR system (Single-Shot LiDAR system을 이용한 Timing Jitter 분석 및 개선 방안)

  • Han, Mun-hyun;Choi, Gyu-dong;Song, Min-hyup;Seo, Hong-seok;Mheen, Bong-ki
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2016.10a
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    • pp.172-175
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    • 2016
  • Time of Flight(ToF) LiDAR(Light Detection And Ranging) technology has been used for distance measurement and object detection by measuring ToF time information. This technology has been evolved into higher precision measurement field such like autonomous driving car and terrain analysis since the retrieval of exact ToF time information is of prime importance. In this paper, as a accuracy indicator of the ToF time information, timing jitter was measured and analyzed through Single-Shot LiDAR system(SSLs) mainly consisting of 1.5um wavelength MOPA LASER, InGaAs Avalanche Photodiode(APD) at 31M free space environment. Additionally, we applied spline interpolation and multiple-shot averaging method on measured data through SSLs to improve ToF timing information.

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A convergence analysis of a PLL for a digital recording channel with an adaptive partial response equalizer (적응 부분응답 등화기를 갖는 디지탈 기록 채널의 PLL 수렴 특성 분석)

  • 오대선;양원영;조용수
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.6
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    • pp.45-53
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    • 1996
  • In this paper, the convergence behavior of timing phase when an adaptive partial response equalizer and decision-directed type of a PLL work together in a digital recording channel is described. The phenomena of getting biased in timing phase when the convergence parameter of an adaptive partial response equalizer and timing recovery constant of a PLL are not selected properly is introduced. The phenomena, occurring due to perturbation of timing phase, are analyzed, by computer simulation and the region of ocnvergence for timing phase is discussed. Also, a method to overcome the phenomena using a variable step-size parameter is described.

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