• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5A
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• pp.469-474
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• 2006

In this paper, we develop a method that derive the average sector throughput of HSDPA system. This proposed method reflects the effects of AMC, scheduling and multi-code transmission, and is performed by simple calculation procedures such as link budget analysis. Link budget table is used to estimate a cell coverage in general. We modify the link budget table in order to calculate C/I of the user according to the location of the user in CDMA packet system employing AMC. Furthermore, we utilize the proposed method to analyze the effects of scheduling and multi-code transmission.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.669-672
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• 2008

In this paper, we propose a constant-amplitude multi-rode trans-bi-orthogonal modulation scheme by introducing a simple constant-amplitude coding scheme with redundant bits and trans-code, which if a modified orthogonal modulation scheme. Generally speaking, the orthogonal modulation scheme is not appropriate for the high speed data transmission applications because of bad bandwidth efficiency. Therefore, we use the multi-rode trans-bi-orthogonal modulation with trans-code for high bandwidth efficiency. Moreover, redundant bits are used for constant-amplitude-coding. Finally, we compare the performance of the proposed scheme with the orthogonal modulation and constant-amplitude multi-code trans-orthogonal modulation by using the computer simulation.

• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.1871-1885
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• 2019

The deterministic MOC code STREAM of the Computational Reactor Physics and Experiment (CORE) laboratory of Ulsan National Institute of Science and Technology (UNIST), was initially designed for the calculation of pressurized water reactor two- and three-dimensional assemblies and cores. Since fast reactors play an important role in the generation-IV concept, it was decided that the code should be upgraded for the analysis of fast neutron spectrum reactors. This paper presents a coupled code - TULIP/STREAM, developed for the fast reactor assembly and core calculations. The TULIP code produces self-shielded multi-group cross-sections using a one-dimensional cylindrical model. The generated cross-section library is used in the STREAM code which solves eigenvalue problems for a two-dimensional assembly and a multi-assembly whole reactor core. Multiplication factors and steady-state power distributions were compared with the reference solutions obtained by the continuous energy Monte-Carlo code MCS. With the developed code, a sensitivity study of the number of energy groups, the order of anisotropic P_N scattering, and the multi-group cross-section generation model was performed on the k_eff and power distribution. The 2D core simulation calculations show that the TULIP/STREAM code gives a k_eff error smaller than 200 pcm and the root mean square errors of the pin-wise power distributions within 2%.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.547-554
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• 2010

In this paper, we propose transmission systems for ultra high definition television (UHDTV) through terrestrial transmission by applying the multi-input multi-output (MIMO) technology. The space time block code, hybrid STBC, V-BLAST and linear dis- persion code are considered to support a high data rate of the UHDTV system. The performance of proposed MIMO systems are evaluated through computer simulations. Then we suggest MIMO parameters, number of antennas and optimal transmission scheme to achieve the transmission rate of the UHDTV system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.5
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• pp.131-138
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• 2008

The channel parameters such as RMS delay spread and Doppler frequency have an effect on performance of system. This paper investigates the effect between the Inter-Code Interference (ICI) and the frequency diversity gain in the multi-rate MC-CDMA system. The multi-rate MC-CDMA system has achieved the more variable data rate than the MC-CDMA and moreover it has the better performance than the OFDMA system, because it has achieved the frquency diversity gain. However, the frequency diversity gain and ICI have a trade-off relationship by using the spreading code. Therefore, we have improved the system performance by efficient choice of system parameters. In order to evaluate the effectiveness of the frequency diversify gain and the ICI effect, we perform simulations by altering the Doppler frequency and RMS delay spread.

• ETRI Journal
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• v.29 no.6
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• pp.835-837
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• 2007

A multi-bit sigma-delta modulator architecture is described for low-distortion performance and a high-speed operation. The proposed architecture uses both a delayed code and a delayed differential code of analog-to-digital converter in the feedback path, thereby suppressing signal components in the integrators and relaxing the timing requirement of the analog-to-digital converter and the scrambler logic. Implemented by a 0.13 ${\mu}m$ CMOS process, the sigma-delta modulator achieves high linearity. The measured spurious-free dynamic range is 89.1 dB for -6 dBFS input signal.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.10
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• pp.16-20
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• 2015

We propose three multi-level modulation codes of the code rate 1/2 for holographic data storage considered as a promising candidate for next generation storage systems. Since a pixel with multi-levels can represent more than 1 bit, it is possible to increase the storage capacity and have many codewords. Thus, we can choose a code that the minimum distance is as far as possible. When we compare the codes with the code rate 1/2, the performance of the code with small number of levels is better than that of large number of levels.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.196-198
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• 2003

Virtually every digital signal processors(DSPs) support on-chip multi- memory banks that allow the processor to access multiple words of data from memory in a single instruction cycle. Also, all existing fixed-point DSPs have irregular architecture of heterogeneous register which contains multiple register files that are distributed and dedicated to different sets of instructions. Although there have been several studies conducted to efficiently assign data to multi-memory banks, most of them assumed processors with relatively simple, homogeneous general-purpose resisters. Therefore, several vendor-provided compilers fer DSPs were unable to efficiently assign data to multiple data memory banks. thereby often failing to generate highly optimized code fer their machines. This paper presents an algorithm that helps the compiler to efficiently assign data to multi- memory banks. Our algorithm differs from previous work in that it assigns variables to memory banks in separate, decoupled code generation phases, instead of a single, tightly-coupled phase. The experimental results have revealed that our decoupled algorithm greatly simplifies our code generation process; thus our compiler runs extremely fast, yet generates target code that is comparable In quality to the code generated by a coupled approach

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1601-1607
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• 2009

As a general rule, the orthogonal modulation scheme which is widely used for wireless communications is not appropriate for the high speed data transmission applications due to the low bandwidth efficiency. Therefore, to increase the bandwidth efficiency of the conventional orthogonal modulation, we propose the multi-code trans-(bi-)orthogonal modulation in this paper. It is the combined scheme of multi-code modulation and trans-orthogonal modulation. We can know that the bandwidth efficiency of the proposed scheme is better than that of the conventional orthogonal modulation. Additionally, the receiver complexity of the proposed scheme is lower than that of the conventional orthogonal modulation. The proposed scheme can be used for the physical layer of the high speed wireless digital data transmission applications such as multimedia communications system and high speed personal area networks.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.223-243
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• 1995

We describe the implementation of a multi-dimensional numerical code to solve the equations for idea! magnetohydrodynamics (MHD) in cylindrical geometry. It is based on an explicit finite difference scheme on an Eulerian grid, called the Total Variation Diminishing (TVD) scheme, which is a second-order-accurate extension of the Roe-type upwind scheme. Multiple spatial dimensions are treated through a Strang-type operator splitting. Curvature and source terms are included in a way to insure the formal accuracy of the code to be second order. The constraint of a divergence-free magnetic field is enforced exactly by adding a correction, which involves solving a Poisson equation. The Fourier Analysis and Cyclic Reduction (FACR) method is employed to solve it. Results from a set of tests show that the code handles flows in cylindrical geometry successfully and resolves strong shocks within two to four computational cells. The advantages and limitations of the code are discussed.