• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.1-10
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• 1998

It is important to know phase offsets of a spreading code in the code division multiple access(CDMA) mobile communication systems because different phase offsets of the same spreading code are used to distinguish each base station. When the period of the code is not that long, the relative phase offset between the code and its shifted code can be found by comparing them, but as the period of the code increases it becomes difficult to find the phase offset. This paper describes a method to calculate the phase offset of a binary code based on the number theoretical approach. We define an accumulator function which plays a central role in this paper, and relationships between the functions are clarified. This number theoretical approach and their results show that this method is very easy for the phase offset calculation. Its application to the CDMA system and circuit realization of the phase offset calculation are also discussed.

• Nuclear Engineering and Technology
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• v.42 no.6
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• pp.636-655
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• 2010

A thermal-hydraulic code, named CUPID, has been being developed for the realistic analysis of transient two-phase flows in nuclear reactor components. The CUPID code development was motivated from very practical needs, including the analyses of a downcomer boiling, a two-phase flow mixing in a pool, and a two-phase flow in a direct vessel injection system. The CUPID code adopts a two-fluid, three-field model for two-phase flows, and the governing equations are solved over unstructured grids with a semi-implicit two-step method. This paper presents an overview of the CUPID code development and assessment strategy. It also presents the code couplings with a system code, MARS, and, a three-dimensional reactor kinetics code, MASTER.

• ETRI Journal
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• v.28 no.2
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• pp.227-230
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• 2006

There has been a growing need for increased capacity in cellular systems. This has resulted in the adoption of the code division multiple access (CDMA) system as a multiple channel access method. Thus, it is important to obtain the phase offsets of binary codes in the CDMA system because distinct phase offsets of the same code are used to distinguish signals received at the mobile station from different base stations. This letter proposes an efficient algorithm to compute the phase offset of a binary code in the CDMA system through the use of the basic facts of number theory and a new notion of the subcodes of a given code. We also formulate the algorithm in a compact form.

• ETRI Journal
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• v.32 no.1
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• pp.142-144
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• 2010

In this letter, we propose GPS L5 acquisition schemes to detect a fast code phase and improve the accuracy of the Doppler frequency. The proposed approach is based on the code-phase changes which occur during the acquisition processing time originating in the Doppler frequency. The proposed schemes detect a fast code phase within about 1 chip near the estimated code phase and improve the accuracy of the Doppler frequency by up to about 4 times in comparison with the popular Septentrio receiver. The feasibility of the proposed schemes is demonstrated through simulation.

• Journal of the Optical Society of Korea
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• v.4 no.1
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• pp.43-47
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• 2000

We studied experimentally a discrete random phase-code multiplexing technique for holographic data storage, which we believe can overcome some disadvantages of conventional random phase-code multiplexing adopting either a diffusion plate or a multimode fiber. Experimental demonstration is presented to show the potential usefulness and some characteristics of the discrete random phase-code multiplexing technique.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.5
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• pp.11-16
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• 1998

DS/CDMA systems for the high speed communication require high code rats. In discrete time CDMA receivers, the performance degradation, caused by the phase difference between transmission code and reference code, increase the sampling frquency of the receiver. This increment of the sampling frequency makes hard to implement high speed CDMA systems. This paper analyzes the SIR(signal to interference Ratio) performance of the discrete time DS/CDMA system, based on the code phase difference. The results of this paper may be useful to study a low-sampling CDMA receiver.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.5
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• pp.10-15
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• 2010

Good performance of spectral-amplitude-coding optical CDMA can be obtained using codes based upon Hadamard matrices, but Hadamard codes have very restrictive code lengths of $2^n$. In this paper a new code family, namely extended Hadamard code, is proposed to relax the code length restriction and the number of simultaneous users. The improved performance of the proposed system is analysed with the consideration of phase-induced intensity noise(PIIN).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.8
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• pp.5-9
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• 2011

Spectral-amplitude-coding optical CDMA systems using codes based upon Hadamard matrices have very restrictive code lengths of $2^n$ and high phase-induced intensity noise(PIIN). In this paper a new code family, namely modified Hadamard code, is proposed to relax the code length restriction and the number of simultaneous users. The improved performance of the proposed system is analysed with the consideration of noise.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2596-2604
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• 1997

There are two kinds of backends in ACK:code generator(full-fledged backend) and code expander(fast backend). Code generators generate target code using string pattern matching and code expanders generate target code using macro expansion. ACK translates EM to SPARC code using code expander. The corresponding SPARC code sequences for a EM code are generated and then push-pop optimization is performed. But, there is the problem of maintaining hybrid stack. And code expander is not considered to passes parameters of a procedure call through register windows. The purpose of this paper is to improve SPARC code quality. We suggest a method of SPARC cod generation using EM tree. Our method is divided into two phases:EM tree building phase and code expansion phase. The EM tree building phase creates the EM tree and code expansion phase translates it into SPARC code. EM tree is designed to pass parameters of a procedure call through register windows. To remove hybrid stack, we extract an additional information from EM code. We improved many disadvantages that arise from code expander in ACK.

• 전자공학회논문지 IE
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• v.44 no.3
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• pp.23-34
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• 2007

For an effective phase multiplexing in a volume holographic system, four types of phase code, pseudo random code(PSC), Hadamard matrix(HAM), pure random code(PRC), equivalent random code(ERC), used as reference beams are generated. In case of $32{\times}32$ address beam, a phase error with 0%, 5%, 10%, 15%, 20%, and 25% error rate, is purposely added to the real phase values in order to consider the practical SLM's nonlinear characteristics of phase modulation in computer simulation. Crosstalks and SNRs(signal-to-ratio) are comparatively analyzed for these phase codes by the auto-correlation and cross-correlation. PSC has the lowest cross-correlation mean value of 0.067 among four types of phase code, which means the SNR of the pseudo random phase code is higher than other phase codes. Also, the standard deviation of the pseudo random phase code indicating the degree of recalled data degradation is the lowest value of 0.0113. In order to analyze the affect by variation of pixel size, simulation is carried out by same method for the case of $32{\times}32$, $64{\times}64$, $128{\times}128$, $256{\times}256$ address beams.