• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.967-975
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• 1998

This paper presents a system to cancel the multi-user interference of synchronous DS/CDMA systems by using the estimation circuit and the reference correlator. In the code-division multiple access(CDMA) scheme, the spectrum of the user's signal is directly spreaded by means of the Simplex coed or the phase offsetted PN code. It is interesting for the Simplex code and the PN code to have a similar correalation property. It these codes are used in DS/CDMA systems, the number of acceptable users can be increased in comparison with conventioal DS/CDMA systems. This thesis presents a interference cancellation model to cancel the multi-use interference in DS/CDMA systems by using Simples code of PN code as a spreading sequence. In AWGN environment, we analyze interference generated from other users and compare the resulting performance with that of the conventioanl receiver in same user side.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.1
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• pp.15-23
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• 2001

In this paper, we propose a system to cancel the multi-user interference of synchronous BPSK DS/CDMA systems. In this CDMA scheme, the spectrum of the user's signal is directly spread by means of the Simplex code or the phase offsetted PN code. But in arbitrary bit interval, we use the one spreading code of the Simplex code and the phase offsetted PN code. The receiver cancel the multi-user interference and demodulate information bits by using reference correlator. This paper presents a interference cancellation model and analyzes this system mathematically. The suggested system show that the interference resulting from other users are remarkably reduced. In AWGN and Nakagami fading environment we analyze interference generated from other users and compare the resulting performance with that of the conventional receiver in same user side.

• Bulletin of the Korean Mathematical Society
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• v.37 no.3
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• pp.493-505
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• 2000

We discuss the class of projective systems whose supports are the complement of the union of two linear subspaces in general position. We express the weight enumerators of the codes generated by these projective systems using two simplex codes corresponding to given linear subspaces. We also prove these codes are uniquely determined upto equivalence by their weight enumerators.

• Korean Management Science Review
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• v.11 no.3
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• pp.13-26
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• 1994

In this paper we studied an integration scheme of some simplex algorithms and some efficient techniques to get the stable solution in linear programming code. And we developed a linear programming package (LPAK) by introducing this scheme and techniques. In LPAK three different algorithms were integrated, which were two primal simplex algorithms using Two phase method and big-M method respectively, and the dual simplex algorithm. LPAK introduces several heuristic techniques in each step of simplex method in order to enhance the stability and efficiency. They were new heuristic methods in structuring initial basis, choosing entering variable, choosing dropping variable and performing reinversion. The experimental results on the NETLIB problems showed that LPAK provided the stable solutions.

• Journal of Industrial Technology
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• v.19
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• pp.361-368
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• 1999

The Nelder-Mead simplex algorithm has become on of the most widely used methods for nonlinear unconstrained optimization, since 1965. Recently, this algorithm has been reevaluated and many papers on this algorithm are being published. The MATLAB computer software, highly renown in engineering, also provides the Nelder-Mead algorithm and the Denis-Woods modification with FMINS function. The authors made C++ code of these algorithms and compared with FMINS on the convergence behavior and the exactness of solutions. It shows that MATLAB's FMINS is inferior to author's C++ code. So, FMINS should be corrected for every user.

• Journal of applied mathematics & informatics
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• v.3 no.1
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• pp.25-34
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• 1996

Many important large-scale linear programs with special structures lead to special computational procedures which are more ef-ficient than the ordinary procedure of the generalized methods. Prob-lems and their solvers taking advantage of multiple updatings of the basis in the dual simplex type method are presented. Computational results run by the efficient algorithm and a presented. Computational results run by the efficient algorithm and a standard code MINOS for the test problems are compared and analyzed. It is shown that the amount of work for the optimal solution for the prblem can be re-duced by the new algorithm.

• Bulletin of the Korean Mathematical Society
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• v.54 no.3
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• pp.731-736
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• 2017

It is well-known that there exists a constant-weight $[s{\theta}_{k-1},k,sq^{k-1}]_q$ code for any positive integer s, which is an s-fold simplex code, where ${\theta}_j=(q^{j+1}-1)/(q-1)$. This gives an upper bound $n_q(k,sq^{k-1}+d){\leq}s{\theta}_{k-1}+n_q(k,d)$ for any positive integer d, where $n_q(k,d)$ is the minimum length n for which an $[n,k,d]_q$ code exists. We construct a two-weight $[s{\theta}_{k-1}+1,k,sq^{k-1}]_q$ code for $1{\leq}s{\leq}k-3$, which gives a better upper bound $n_q(k,sq^{k-1}+d){\leq}s{\theta}_{k-1}+1+n_q(k-1,d)$ for $1{\leq}d{\leq}q^s$. As another application, we prove that $n_q(5,d)={\sum_{i=0}^{4}}{\lceil}d/q^i{\rceil}$ for $q^4+1{\leq}d{\leq}q^4+q$ for any prime power q.

• Journal of the Korean Mathematical Society
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• v.47 no.6
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• pp.1167-1182
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• 2010

We study codes meeting a generalized version of the Singleton bound for higher weights. We show that some of the higher weight enumerators of these codes are uniquely determined. We give the higher weight enumerators for MDS codes, the Simplex codes, the Hamming codes, the first order Reed-Muller codes and their dual codes. For the putative [72, 36, 16] code we find the i-th higher weight enumerators for i = 12 to 36. Additionally, we give a version of the generalized Singleton bound for non-linear codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.491-496
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• 2015

In this paper, we introduce two classes of optimal codes, [$2^k-1$, k, $2^{k-1}$] simplex codes and [$2^k-1+k$, k, $2^{k-1}+1$] codes, attaining Griesmer bound with equality. We further present and compare the locality of them. The [$2^k-1+k$, k, $2^{k-1}+1$] codes have good locality property as well as optimal code length with given code dimension and minimum distance. Therefore, we expect that [$2^k-1+k$, k, $2^{k-1}+1$] codes can be applied to various distributed storage systems.

• Journal of the Korean Operations Research and Management Science Society
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• v.11 no.1
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• pp.51-58
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• 1986

The propose of this study is to presnet a generalized linear/goal programming software, which has been developed to run on mickrocomputers with at least 512 K bytes of memory. The main characteristics of our algorithm for solving LP/GP problems are outlined as follows ; First, it uses the revised simplex algorithm, which is the most efficient computational procedure for computers. Second, it employs the sparse matrix technique to overcome the limited memory of microcomputers. Last, it uses the modified product form of invers (MPFI) to reduce round-off errors. The test runs with our code written in FORTRAN show that it can be used as an effective tool for solving linear/goal programming problems of considerable size.