• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.2
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• pp.11-20
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• 2002

In this paper, for many prime power q, it is shown that new cyclic relative difference sets with parameters (equation omitted) can be constructed by using d-homogeneous functions on $F_{q^{n}}${0} over $F_{q}$ with difference-balanced property, where $F_{q^{n} }$ is a finite field with $q^{n}$ elements. Several new cyclic relative difference sets with parameters (equation omitted) are constructed by using p-ary sequences of period $q^{n}$ -1 with ideal autocorrelation property introduced by Helleseth and Gong and d-form sequences.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.1
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• pp.21-32
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• 2002

In this paper, for any prime q, new cyclic difference sets with Singer parameter equation omitted are constructed by using the q-ary sequences (d-homogeneous functions) of period $q_n$-1. When q is a power of 3, new cyclic difference sets with Singer parameter equation omitted are constructed from the ternary sequences of period $q_n$-1 with ideal autocorrealtion found by Helleseth, Kumar and Martinsen.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7A
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• pp.1257-1263
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• 2001

In the paper, the p-ranks and characteristics polynomials of cyclic difference sets are derived by expanding the trace expression of their characteristic sequences. By using this method, it is shown that the 3-ranks and characteristic polynomials of Helleseth-Kumar-Martinsen (HKM) difference set and Lin difference set can be easily obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1351-1358
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• 2012

In this paper, an analytical technique is proposed for the design of interleaved thinned planar array with well-behaved and predictable sidelobes. The interleaved arrays are composed of thinned planar subarrays based on cyclic difference sets(DSs). Becauce sidelobes of thinned planar subarrays based on DS are predictable by DS parameters, the subarrays exhibit very similar sidelobe levels by utilizing DS and complementary DS with similar autocorrelations each other. The combinatorial method also allows the design of interleaved placements with simultaneously optimum peak sidelobe levels(PSLs) of subarrays using cyclic shift-a property of DSs. The optimized PSLs of the interleaved array are -12.47 dB and -10.34 dB.

• East Asian mathematical journal
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• v.26 no.5
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• pp.655-670
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• 2010

The complete multipartite graph $K_{n(m)}$ with n $ {\geq}$ 4 partite sets of size m is shown to have a decomposition into 4-cycles in such a way that vertices of each cycle belong to distinct partite sets of $K_{n(m)}$, if 4 divides the number of edges. Such cycles are called gregarious, and were introduced by Billington and Hoffman ([2]) and redefined in [3]. We independently came up with the result of [3] by using a difference set method, and improved the result so that the composition is circulant, in the sense that it is invariant under the cyclic permutation of partite sets. The composition is then used to construct gregarious 4-cycle decompositions when one partite set of the graph has different cardinality than that of others. Some results on joins of decomposable complete multipartite graphs are also presented.

• Earthquakes and Structures
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• v.22 no.6
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• pp.539-548
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• 2022

Steel plate shear walls (SPSWs) are one of the most important and widely used lateral load-bearing systems. The reason for this is easier execution than reinforced concrete (RC) shear walls, faster construction time, and lower final weight of the structure. However, the main drawback of SPSWs is premature buckling in low drift ratios, which affects the energy absorption capacity and global performance of the system. To address this problem, two groups of SPSWs under cyclic loading were investigated using the finite element method (FEM). In the first group, several series of circular rings have been used and in the second group, a new type of SPSW with concentric circular rings (CCRs) has been introduced. Numerous parameters include in yield stress of steel plate wall materials, steel panel thickness, and ring width were considered in nonlinear static analysis. At first, a three-dimensional (3D) numerical model was validated using three sets of laboratory SPSWs and the difference in results between numerical models and experimental specimens was less than 5% in all cases. The results of numerical models revealed that the full SPSW undergoes shear buckling at a drift ratio of 0.2% and its hysteresis behavior has a pinching in the middle part of load-drift ratio curve. Whereas, in the two categories of proposed SPSWs, the hysteresis behavior is complete and stable, and in most cases no capacity degradation of up to 6% drift ratio has been observed. Also, in most numerical models, the tangential stiffness remains almost constant in each cycle. Finally, for the innovative SPSW, a relationship was suggested to determine the shear capacity of the proposed steel wall relative to the wall slenderness coefficient.