• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.5
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• pp.1138-1144
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• 2013

Cross-correlation functions of maximal period sequences have been studied for decades. In this paper, we find the cross-correlation values of non-linear sequences $S_a^r(t)=Tr_1^m\{[Tr_m^n(a{\alpha}^t+{\alpha}^{dt})]^r\}$ having the maximal period $2^n-1$ for Niho type decimation $d=2^{m-2}(2^m+3)$, where n=2m. In particular, we call d Niho type decimation in case $d{\equiv}1(mod\;2^m-1)$. And we analyze the cross-correlation distributions of $S_a^r(t)$ when the phase shift ${\tau}=(2^m+1)k(0{\leq}k{\leq}2^m-2)$ and provide experiment results.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.166-168
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• 2001

3D GIS(Geographical Information System)은 2D GIS를 고도값을 고려한 3D 공간으로 확장한 GIS System이다. 3D GIS는 기존의 2D와는 다른 Data Format을 기반으로 훨씬 다양한 기능을 지원하는 Operation들을 제공한다. 본문에서는 각 노드들의 상관 관계를 묘사하는 데 장점을 가진 Topological Data Model에 대해 알아보고, 이 모델에서 지원이 가능한 여러 가지의 3D Operation들을 알아보고 도시내의 다양한 상황하에서 기능을 지원 할 수 있도록 한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.263-269
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• 2013

In this paper we give a proof for finding the values of the cross-correlation function $C_d({\tau})$, when $d=3{\cdot}2^m-2$ where n=2m, m=4k ($k{\geq}2$). And the linear span of the sequences in the proposed sequence family are derived in the some cases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7C
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• pp.534-539
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• 2008

For an odd prime p, n=4k, and $d=((p^{2k}+1)/2)^2$, Seo, Kim, No, and Shin derived the correlation distribution of p-ary m-sequence of period $p^n-1$ and its decimated sequences by d. In this paper, two new families of p-ary sequences with family size $p^{2k}$ and maximum correlation magnitude $[2]sqrt{p^n}-1$ are constructed. The linear complexity of new p-ary sequences in the families are derived in the some cases and the upper and lower bounds of their linear complexity for general cases are presented.

• Journal of Advanced Navigation Technology
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• v.26 no.3
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• pp.166-171
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• 2022

In this paper, we propose an algorithm to improve DoA(direction of arrival) estimation performance of the subspace-based method by generating high robustness correlation matrix of the signals incident on the uniformly linear array antenna. The existing subspace-based DoA estimation method estimates the DoA by obtaining a correlation matrix and dividing it into a signal subspace and a noise subspace. However, the component of the correlation matrix obtained from the low SNR and small number of snapshots inaccurately estimates the signal subspace due to the noise component of the antenna, thereby degrading the DoA estimation performance. Therefore a robust correlation matrix is generated by arranging virtual signal vectors obtained from the existing correlation matrix in a sliding manner. As a result of simulation using MUSIC and ESPRIT, which are representative subspace-based methods,, the computational complexity increased by less than 2.5% compared to the existing correlation matrix, but both MUSIC and ESPRIT based on RMSE 1° showed superior DoA estimation performance with an SNR of 3dB or more.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.264-273
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• 2012

The purpose of this study was to determine the test-retest reliability and the concurrent validity between tinetti mobility test (TMT), berg balance scale (BBS) and space balance 3D which is one of the computerized measurement and visual feedback balance assessment system in subacute stroke patients. Twenty three ambulatory acute stroke subjects were measured the TMT, BBS and space balance 3D. The test-retest reliability(intra-class correlation coefficient: ICC) indicated that the static and dynamic balance in space balance 3D considered moderate reliability and TMT, BBS were good reliability. In case of concurrent validity, there were moderate validity (p<.01) between static balance test with space balance 3D and each TMT, BBS. But there were only poor validity (p<.05) between center to forward-left, center to backward-left phase in dynamic balance test with space balance 3D and each TMT, BBS. These findings suggest that in subacute stroke patients the test-retest reliability and concurrent validity using the space balance 3D and TMT were valuable in balance test but there was limitation to evaluate dynamic balance test.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.29-34
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• 2001

In this paper, we designed an LSF coefficient quantizer of the wideband speech codec that can produce high quality speech service. For the efficient LSF coefficient quantizer, the interframe correlation was used. Also we separately quantized the LSF coefficients with high and low interframe correlation. Predictive pyramid vector quantizer (PVQ) was used for quantizing the LSF coefficients with high interframe correlation, and PVQ was used for quantizing the LSF coefficients with low interframe correlation. Experiments show that the proposed UF quantizer can quantize LSF information in 40 bits/frame, with an average spectral distortion (SD) of 1 dB and less than 3.87% frames having SD greater than 2 dB.

• Journal of radiological science and technology
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• v.39 no.3
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• pp.337-344
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• 2016

The purpose of this study was to evaluate the radiolucency for the phantom output to the 3D printing technology. The 3D printing technology was applied for FDM (fused deposition modeling) method and was used the material of ABS (acrylonitrile butadiene styrene) resin. The phantom was designed in cylindrical uniformity. An image uniformity was measured by a cross-sectional images of the 3D printed phantom obtained from the CT equipment. The evaluation of radiolucency was measured exposure dose by the inserted ion-chamber from the 3D printed phantom. As a results, the average of uniformity in the cross-sectional CT image was 2.70 HU and the correlation of radiolucency between PMMA CT phantom and 3D printed ABS phantom is found to have a high correlation to 0.976. In the future, this results will be expected to be used as the basis for the phantom production of the radiation quality control by used 3D printing technology.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.249-250
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• 2009

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.1
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• pp.58-64
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• 2009

The objectives of this study were to investigate the aggregate fragmentation in wet-sieving and to evaluate the relationship between the aggregate fragmentation fractal dimension and macro-porosity of upland soils, using three different textural types of soils including Gopyeng series (Fine, Typic Hapludalfs), Gyuam series (Fine silty over coarse silty, Fluvaquentic Eutrudepts), and Jungdong series (Coarse loamy, Typic Udifluvents) located in Gyeonggi province. Undisturbed soil samples with five replicates were seasonally sampled and used for measuring water stable aggregate, macropores, and physico-chemical properties of soils. The aggregate stability in wet-sieving was digitalized as three types of fragmentation fractal dimension ($D_f$), geometric mean diameter (GMD), and mean weight diameter (MWD). $D_f$ had higher correlation with GMD than with MWD. Seasonal aggregate stability showed the highest values in summer, and decreased in the order of spring and autumn. The macroporosity had higher in topsoil, in autumn, and in ridge, than in plow pan layer, in summer, and in row, respectively. The relationship between $D_f$ and macroporosity, especially more than 99 m, showed high correlation only in soils with $D_f$ less than 3.1, which means more aggregated soils compared to soils with $D_f$ more than 3.1. Besides, in the soils with the fractal dimension less than 3.1, the power function relation between saturated hydraulic conductivity and macroporosity more than 99 m had relatively high determinant coefficient, and vice versa. Therefore, it could be thought that fragmentation fractal dimension is available for confirming macroporosity induced from aggregation.