• Title/Summary/Keyword: Code Phase

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A New Efficient Acpuisition Method and Its Implementation using the Phase Offset of Binary Code (이원부호 위상 오프셋를 이용한 새로운 방식의 동기 획득 시스템 구현)

  • 김동희;한영열
    • Proceedings of the IEEK Conference
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    • 1998.06a
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    • pp.11-14
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    • 1998
  • This paper introuces a new efficient method of synchronization acquisition which is the most important element in DS-CDMA system using the phase offset of binary code. This approach uses the binary code function which can easily estimate the phase offset from the received spreading waveforms which respect to the receiver-stored replica of the spreading code. This paper proposes the initial acquisition model with repeat error control device that is good for perfomance. The hardware is implemented by TMS320c30

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Performance Analysis of Complex Phase-code for Phase Multiplexes Holographic Memory System (위상 다중화 홀로그래픽 메모리 시스템을 위한 CPC 위상코드의 성능 분석)

  • 조병철;김정진;김은수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.1C
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    • pp.1-8
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    • 2003
  • In this paper, performance of the CPC(complex phase code) which is recently proposed as a practical phase encoding method for phase-code multiplexes holographic memory system is comparatively analyzed with those of the conventional phase codes such as PR(pure random code), RCE(random code with equality), WHM(Walsh Hadamard Matrix). In computer simulation, the size of an address bean is fixed at 32$\times$32 pixels and 0%-25% phase-error ratio in a pixel are intentionally added to the real phase values to consider the nonlinear phase-modulation characteristics of the practical spatial light modulator. From comparative analysis of crosstalks and signal-to-noise ratios for these phase codes by calculating auto-correlation and cross-correlation, it is found that the CPC have the lowest cross-correlation mean value of 0.021, the lowest standard deviation of 0.0113 and the highest signal-to-noise ratio(SNR) of 27.4 among the four types of phase code. In addition, from the calculation of the number of all possible address beams for these four types of phase code as the size of the address beam is fixed to 3232 pixels, the CPC is found to have 6.334$\times$10$^{49}$ address beams, which are relatively higher number than that of the conventional phase codes.

RECENT IMPROVEMENTS IN THE CUPID CODE FOR A MULTI-DIMENSIONAL TWO-PHASE FLOW ANALYSIS OF NUCLEAR REACTOR COMPONENTS

  • Yoon, Han Young;Lee, Jae Ryong;Kim, Hyungrae;Park, Ik Kyu;Song, Chul-Hwa;Cho, Hyoung Kyu;Jeong, Jae Jun
    • Nuclear Engineering and Technology
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    • v.46 no.5
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    • pp.655-666
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    • 2014
  • The CUPID code has been developed at KAERI for a transient, three-dimensional analysis of a two-phase flow in light water nuclear reactor components. It can provide both a component-scale and a CFD-scale simulation by using a porous media or an open media model for a two-phase flow. In this paper, recent advances in the CUPID code are presented in three sections. First, the domain decomposition parallel method implemented in the CUPID code is described with the parallel efficiency test for multiple processors. Then, the coupling of CUPID-MARS via heat structure is introduced, where CUPID has been coupled with a system-scale thermal-hydraulics code, MARS, through the heat structure. The coupled code has been applied to a multi-scale thermal-hydraulic analysis of a pool mixing test. Finally, CUPID-SG is developed for analyzing two-phase flows in PWR steam generators. Physical models and validation results of CUPID-SG are discussed.

GPS L5 Acquisition Schemes for Rapid Code Phase Search and Fine Doppler Determination (GPS L5 신호에서 신속한 코드위상 재검색 및 정밀 도플러 결정 기법)

  • Joo, In-One;Choi, Seung-Hyun;Kim, Jae-Hyun;Shin, Chun-Sik;Lee, Sang-Uk;Kim, Jae-Hoon
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.17 no.4
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    • pp.17-24
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    • 2009
  • According to the GPS modernization, L5 is the third civilian GPS signal, broadcasts in a radio band reserved exclusively for aviation safety services. However, as the code length of GPS L5 is ten times longer than that of GPS L1, the acquisition processing time in GPS L5 takes longer than that of L1. This characteristics make the code phase detected initially change and cause the tracking loop to unlock. In order to overcome this problem, this paper proposes L5 acquisition schemes for the rapid code phase re-search and the fine doppler determination. The feasibility of the proposed scheme is demonstrated through the simulation results.

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A DS/CDMA Code Acquisition Scheme to Reduce the System Performance Variation Resulting from Residual Code Phase Offset (나머지 부호 위상차가 일으키는 시스템 성능변화를 줄이는 직접수열 부호분할 다중접속 부호 획득 방법)

  • Yun, Seok-Ho;Yun, Hyeong-Sik;Song, Ik-Ho;Kim, Seon-Yong;Lee, Yong-Eop
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.37 no.4
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    • pp.25-34
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    • 2000
  • In this paper, we first investigate the effect of residual code phase offset on the DS/CDMA code acquisition scheme. When the code phase offset normalized to the chip duration is within the advancing step size, the sum of two successive matched filter outputs has a constant value regardless of the residual code phase offset if noise is absent. Based on this observation, we propose a new code acquisition scheme, and investigate the performance of the scheme. The Proposed code acquisition scheme is analyzed, and numerical results are given to show that the proposed scheme is more robust to the variation of the residual code phase offset and has better performance than the conventional scheme.

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Experimental investigation and validation of TASS/SMR-S code for single-phase and two-phase natural circulation tests with SMART-ITL facility

  • Bae, Hwang;Chun, Ji-Han;Yun, Eunkoo;Chung, Young-Jong;Lim, Sung-Won;Park, Hyun-Sik
    • Nuclear Engineering and Technology
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    • v.54 no.2
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    • pp.554-564
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    • 2022
  • The natural circulation phenomena occurring in fully integrated nuclear reactors are associated with a unique formation mechanism. The phenomenon results from a structural feature of these reactors involving upward flow from the core, located in the central-bottom region of a single vessel, and downward flow to the steam generator in the annulus region. In this study, to understand the natural circulation in a single vessel involving a multi-layered flow path, single-phase and two-phase natural circulation tests were performed using the SMART-ITL facility, and validation analysis of the TASS/SMR-S code was performed by comparing the corresponding test results. Three single-phase natural circulation tests were sequentially conducted at 15%, 10%, and 5% of full-scaled core-power without RCP operation, following which a two-phase natural circulation test was successively conducted with an artificial discharge of coolant inventory. The simulation capability of the TASS/SMR-S code with respect to the natural circulation phenomena was validated against the test results, and somewhat conservative but reasonably comparative results in terms of overall thermalhydraulic behavior were shown.

MULTI-SCALE THERMAL-HYDRAULIC ANALYSIS OF PWRS USING THE CUPID CODE

  • Yoon, Han Young;Cho, Hyoung Kyu;Lee, Jae Ryong;Park, Ik Kyu;Jeong, Jae Jun
    • Nuclear Engineering and Technology
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    • v.44 no.8
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    • pp.831-846
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    • 2012
  • KAERI has developed a two-phase CFD code, CUPID, for a refined calculation of transient two-phase flows related to nuclear reactor thermal hydraulics, and its numerical models have been verified in previous studies. In this paper, the CUPID code is validated against experiments on the downcomer boiling and moderator flow in a Calandria vessel. Physical models relevant to the validation are discussed. Thereafter, multi-scale thermal hydraulic analyses using the CUPID code are introduced. At first, a component-scale calculation for the passive condensate cooling tank (PCCT) of the PASCAL experiment is linked to the CFD-scale calculation for local boiling heat transfer outside the heat exchanger tube. Next, the Rossendorf coolant mixing (ROCOM) test is analyzed by using the CUPID code, which is implicitly coupled with a system-scale code, MARS.

DEVELOPMENT AND PRELIMINARY ASSESSMENT OF A THREE-DIMENSIONAL THERMAL HYDRAULICS CODE, CUPID

  • Jeong, Jae-Jun;Yoon, Han-Young;Park, Ik-Kyu;Cho, Hyoung-Kyu;Lee, Hee-Dong
    • Nuclear Engineering and Technology
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    • v.42 no.3
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    • pp.279-296
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    • 2010
  • For the analysis of transient two-phase flows in nuclear reactor components, a three-dimensional thermal hydraulics code, named CUPID, has been developed. The CUPID code adopts a two-fluid, three-field model for two-phase flows, and the governing equations were solved over unstructured grids, which are very useful for the analysis of flows in complicated geometries. To obtain numerical solutions, the semi-implicit numerical method for the REALP5 code was modified for an application to unstructured grids, and it has been further improved for enhanced accuracy and fast running. For the verification of the CUPID code, a set of conceptual problems and experiments were simulated. This paper presents the flow model, the numerical solution method, and the results of the preliminary assessment.

A reference code design for PN code acquisition in DS/SS CDMA systems (DS/SS CDMA 시스템 하에서 유사임의 코드 획득을 위한 reference code 설계)

  • 원승환;장승용;김운경
    • Proceedings of the IEEK Conference
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    • 2000.11a
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    • pp.65-68
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    • 2000
  • In CDMA, the currently used PN code acquisition methods detect the phase of the incoming PN signal on the basis of ML estimation. In serial search strategy, it takes relatively long time for PN code acquisition. A study related to reduce processing time of PN code acquisition is important. Therefore we propose a reference code design for a new algorithm that a reference code and the received PN code are fully correlated to detect the transmitted PN code, in detail, the relative phase offset j of c⒡. After choosing two weight factors, we show the mathematical analysis and derivation for the reference code design.

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Development of Numerical Code for Interior Ballistics and Analysis of Two-phase Flow according to Drag Models (강내탄도 전산해석 코드 개발과 항력 모델에 따른 이상유동 분석)

  • Sung, Hyung-Gun;Jang, Jin-Sung;Yoo, Seung-Young;Roh, Tae-Seong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.15 no.6
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    • pp.38-46
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    • 2011
  • In order to simulate the ignition-gas injection in the interior ballistics, a two-dimensional analytic code for two-phase flows has been developed. The Eulerian-Lagrangian approach and the low-dissipation simple high-resolution upwind scheme(LSHUS) have been adopted in the numerical code for the propellant combustion of the gun propelling charges. The ghost-cell extrapolation method has been used for the moving boundary in the chamber with the projectile movement. The calculation results of the developed code have been compared and verified through those of the dimensionless IBHVG2 code and the previous one-dimensional code. In comparison with the two-phase flows according to the drag models, the numerical analysis of the muzzle velocity has been affected by the drag model.