• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.194-200
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• 2012

In this paper we analyze the code sequence generating algorism defined on $GF(2^n)$ proposed by S.Bostas and V.Kumar[7] and derive the implementation functions of code sequence generator using Boolean functions which can map the vector space $F_2^n$ of all binary vectors of length n, to the finite field with two elements $F_2$. We find the code sequence generating boolean functions based on two kinds of the primitive polynomials of degree, n=5 and n=7 from trace function. We then design and implement the code sequence generators using these functions, and produce two code sequence groups. The two groups have the period 31 and 127 and the magnitudes of out of phase(${\tau}{\neq}0$) autocorrelation and crosscorrelation functions {-9, -1, 7} and {-17, -1, 15}, satisfying the period $L=2^n-1$ and the correlation functions $R_{ij}({\tau})=\{-2^{(n+1)/2}-1,-1,2^{(n+l)/2}-1\}$ respectively. Through these results, we confirm that the code sequence generators using boolean functions are designed and implemented correctly.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.120-128
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• 1996

An attempt is made to characterize and synthesize engineered surfaces. The proposed method is not only an analytical tool to characterize but also to generate/synthesize three-dimensional surfaces. The developed method expresses important engineered surface characteristics such as the autocorrelation or power spectrum density functions in terms of the two-dimensional autoregressive coefficients.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.511-517
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• 1998

In this paper a new technique to generate spreading code sequences in the CDMA communication is introduced. It is an effective method to generate optimal code sequences using the orthogonality of wavelet packet basis set of subspaces. With a three-stage Quadrature Mirror Filter(QMF), generation of optimal code sequences has been demonstrated. Since these generated optimal code sequences are non-binary and have an arbitrary waveform which is different from that of the conventional PN-based Gold code sequences, a strong security against the intended interceptor is feasible. Encouraging good correlation properties are also achieved with this new method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.521-525
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• 1996

An attempt is made to characterize and synthesize engineered surfaces. The proposed method is not only an analytical tool to characterize but alsoto generate/synthesize three-dimensional surfaces. The developed method expresses important engineered surface characteristics such as the autocorrelation or pwoer spectrum density functions in terms of the two-dimensional autoregressive coefficients.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.113-116
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• 2001

지금까지 지리 데이터를 다루는 다양한 시스템들은 서로 독립적으로 개발되어 왔다. 최근에는 이러한 시스템에 분산되어 있는 방대한 양의 데이터에 대한 상호 운용성이 요구되고 있으며 이를 지원하기 위해 개방형 GIS 명세서의 2 차원 공간 모델을 확장한 3 차원 시공간 데이터 모델을 제안하였다. 또한 제안된 모델을 컴포넌트 형태로 제공함으로써 컴포넌트의 장점인 확장성과 재사용성을 그대로 수용하였다. 특히 제안된 모텔에서의 이동 객체는 이력 객체와 동일한 자료 구조로 저장되므로, 이동 객체의 경우 시간에 따른 연속적인 데이터의 변화를 표현하기 위해 각 버전간의 관계에 대한 정의가 필요하다. 따라서 이 논문에서는 3 차원 시공간 상에서 이동 객체를 이동 점 계열의 객체와 이동 영역 계열의 객체로 나누어 논의하고, 이동 객체의 시간적 특성과 공간적 특성에 따른 변화를 효율적으로 표현하기 위한 내부 구조를 설계하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.2
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• pp.48-54
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• 2014

For the element ${\alpha}{\in}GF(p^n)$, two kinds of bases are known. One is a conventional polynomial basis of the form $\{1,{\alpha},{\alpha}^2,{\cdots},{\alpha}^{n-1}\}$, and the other is a normal basis of the form $\{{\alpha},{\alpha}^p,{\alpha}^{p^2},{\cdots},{\alpha}^{p^{n-1}}\}$. In this paper we consider the method of generating normal bases which construct the finite field $GF(p^n)$, as an n-dimensional extension of the finite field GF(p). And we analyze the code sequence generating algorithm and derive the implementation functions of code sequence generator based on the normal bases. We find the normal polynomials of degrees, n=5 and n=7, which can generate normal bases respectively, design, and construct the code sequence generators based on these normal bases. Finally, we produce two code sequence groups(n=5, n=7) by using Simulink, and analyze the characteristics of the autocorrelation function, $R_{i,i}(\tau)$, and crosscorrelation function, $R_{i,j}(\tau)$, $i{\neq}j$ between two different code sequences. Based on these results, we confirm that the analysis of generating algorithms and the design and implementation of the code sequence generators based on normal bases are correct.

• Environmental and Resource Economics Review
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• v.13 no.1
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• pp.83-117
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• 2004

This study investigates the spatial distributions of the ambient levels of air pollutants ($SO_2$, $NO_2$, $O_3$, CO, and PM) in Seoul metropolitan area using the data obtained by the air pollution observation stations. This study estimated a non-parametric kernel density function and two types of inequality indices, Gini and Entropy. Our estimation results show that the degree of inequality in spatial distribution of air pollution, in general, tends to be stable or slightly decreasing for the period of 1990~2001. In addition, we found that there are significant dynamics of air pollution levels in terms of spatial ranking.

• Journal of Korean Association for Spatial Structures
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• v.9 no.3
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• pp.75-82
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• 2009

This paper investigates the variation of post-buckling behaviours of spatial structures after sizing optimization with linear assumptions. The mathematical programming technique is used to produce the optimum member size of spatial structures against external load. Total weight of structure is considered as the objective function to be minimized and the displacement occurred at loading point and member stresses of structures are used as the constraint functions. The finite difference method is used to calculate the design sensitivity of objective function with respect to design variables. The post-buckling analysis carried out by using the geometrically nonlinear finite element analysis code ISADO-GN. It is found to be that there is a huge difference between the post buckling behaviours of the initial and optimized structures. Therefore, the stability of optimized spatial structures with linear assumption should be throughly checked by appropriate nonlinear analysis techniques. Finally, the present numerical results are provided as benchmark test suite for future study of large spatial structures.

• Environmental and Resource Economics Review
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• v.18 no.1
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• pp.105-138
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• 2009

This study investigates the spatial distribution of the degree of water pollutants in Han River using data obtained by the water pollution observation stations. This study estimates a non -parametric kernel density function for each water pollutants, and tests a significant difference between two estimated distribution functions. Next, Generalized Entropy inequality indices are evaluated and this research tests difference of inequality indices between two years using bootstrapping method. Lastly in a dynamic of view, it is analyzed that there are significant changes in the ranking of water pollution level. Estimation results show that the degree of inequality in spatial distribution of water pollution tends to be stable or decreasing for last 15 years in a great part of water pollutants, and ranking of water pollution level hardly changes in Han River.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.107-112
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• 2008

This paper investigates the variation of post-buckling behaviours of 2-dimensional shallow arch type truss after sizing optimization. The mathematical programming technique is used to produce the optimum member size of 2D arch truss against a central point load. Total weight of structure is considered as the objective function to be minimized and the displacement occurred at loading point and member stresses of truss are used as the constraint functions. The finite difference method is used to calculate the design sensitivity of objective function with respect to design variables. The postbuckling analysis carried out by using the geometrically nonlinear finite element analysis code ISADO-GN. It is found to be that there is a huge change of post-buckling behaviour between the initial structure and optimum structure. Numerical results can be used as useful information for future research of large spatial structures.