• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.895-907
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• 2006

In this study, in order to maximize the accuracy and efficiency of the existing interpolation method fractal methods are applied. Developed FEDISA model revives the irregularity of the real terrain with only a few information about base terrain, which can produce almost complete geographic information. The area of the model is set to $150m{\times}150m$, $300m{\times}300m$, $600m{\times}600m$, $1,200m{\times}1,200m$ to compare the real data with the data of the existing interpolation method and FEDISA model. By statistical verification of the results, the adaptability and efficiency of FEDISA model are investigated. It seems that FEDISA model will help a lot to obtain the terrain information about the changed terrain, such as the bottom of reservoirs and dams as well as large amount of destruction due to cutting and banking.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.5
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• pp.61-71
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• 1998

Genetic Algorithm(GA) is a method of approaching optimization problems by modeling and simulating the biological evolution. GA needs large time-consuming, so ti had better do on a parallel computer architecture. Our proposed system has a VLSI-oriented interconnection network, which is constructed from a viewpoint of fractal geometry, so that self-similarity is considered in its configuration. The approach to Parallel Genetic Algorithm(PGA) on our proposed system is explained, and then, we construct the classifier system such that the set of samples is classified into weveral classes based on the features of each sample. In the process of designing the classifier system, We have applied PGA to the Traveling Salesman Problem and classified the sample set in the Euclidean space into several categories with a measure of the distance.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.2
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• pp.82-95
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• 1998

In this paper, we propose a text-independent speaker identification system which has a classifier composed of two parts; to calculate the degree of likeness of each speech frame and to select the most probable speaker from the entire speech duration. The first part is realized using RBFN which is selforganized through learning and in the second part the speaker is determined using a con-tbination of MAXNET and delayed summings. And we use features from linear speech production model and features from fractal geometry. Closed-set speaker identification experiments on 13 male homogeneous speakers show that the proposed techniques can achieve the identification ratio of 100% as the number of delays increases.

• Journal of Energy Engineering
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• v.18 no.3
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• pp.175-190
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• 2009

This study examines the influence of scale economy, technology, financing capability and market competition on economic performance by value chain in Korean solar energy companies, using the multiple logistic regression analysis. The current profit ratio is analyzed to have been positively affected by financing capability, while negatively by market competition. The scale economy and technology are analyzed to have no statistical significance on the economic performance. The current profit ratio for companies creating higher value in the sourcing process is negatively affected by technology while positively by financial capability. The one in the manufacturing process is affected positively by technology and financing capability, and the one in the marketing process is affected positively by financing capability while negatively by market competition. The implications of this study are as follows: Korean solar energy industry is recommended i) to establish the specific innovation system for technology development, ii) to set up advanced financial system, iii) to carry out the fractal system, the manufacturing system through the network of the firms owning core competence per value chain.

• Journal of the KSME
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• v.31 no.6
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• pp.540-550
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• 1991

chaos이론은 현재 사회과학과 자연과학의 많은 분야에 있어서 연구 수단 또는 연구 대상으로서의 폭발적인 인기를 누리고 있다. 열 . 유체역학, 동력학, 구조역학, 화학(화학 분야에 있어서의 chaos개념은 Prigogine(1978년Nobel상 수상자)과 Stengers의 저서에 잘 기술되어 있음), 플라즈마 물리학, 전자공학, 전기공학 등 우리들에게 친숙한 학문은 말할 것 없고, 의학, 생태학, 생물학, 인구학, 경제학, 회계학 등에서도 종래의 것과는 완전히 다른 시각에서 현상을 분석하고 예측하 려는 노력을 하고 있다. 그리고 최근에는 computer graphics 에서도 간단한 수식 모델로 fractal set를 형성시켜, 각종 나무, 꽃, 파도, 구름등 자연의 산물들을 성공적으로 묘사하고 있다. Gleick는 chaos이론에 의한 각 분야에 있어서의 새로운 현상을 Newton-Einstein 이후의 또 다른 과학 혁명이라 부르고 있다. 그리고, 지금까지의 서양 학문이 줄곧 세부화의 길을 달려 왔으나 chaos에 의해 그 과정이 역으로 될 것이라는 인식이 일고 있다. 이는 chaos의 질서의 법칙이 보편타당성(universality)의 일면을 갖고 있다는데 기인되며, 종합화를 지향하는 동양의 제반 학 문과 그 성격상 일맥상통한 점이 있어, chaos학이 동양인의 기호 학문이 되리라 믿는다.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.696-701
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• 2002

This paper describes some results of change detection in Tokyo metropolitan area, Japan , using the Landsat TM data, and methods to quantify the ground cover classes. The changes are analyzed using the measures of not only conventional spectral classes but also a set of landscape indices to describe spatial properties of ground cove types using fractal dimension of objects, entropy in the specific windows defining the neighbors of focusing locations. In order eliminate the seasonal radiometric effects on TM data, an automated class labeling method is also attempted. Urban areas are also delineated automatically by defining the boundaries of the urban area. These procedures for urban change detection were implemented by the unified image computing methods proposed by the author, they can be automated in coherent and systematic ways, and it is anticipated to automate the whole procedures. The results of this analysis suggest that Tokyo metropolitan area was extended to the suburban areas along the new transportation networks and the high density area of Tokyo were also very much extended during the period between 1985 and 1995.

• Nonlinear Functional Analysis and Applications
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• v.26 no.1
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• pp.137-155
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• 2021

In this paper, first, we prove some common fixed point theorems for the generalized contraction condition under newly defined modified simulation function which generalize and include many results in the literature. Second, we give two numerical examples with graphical representations for verifying the proposed results. Third, we discuss and study a set of common fixed point theorems for two pairs (finite families) of self-mappings. Finally, we give some applications of our results in discrete and functional fractional economic systems.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.4
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• pp.341-353
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• 2022

Pipelines are buried in urban area, and the position (depth and orientation) of buried pipeline should be clearly identified before ground excavation. Although various geophysical methods can be used to detect the buried pipeline, it is not easy to identify the exact information of pipeline due to heterogeneous ground condition. Among various non-destructive geo-exploration methods, ground penetration radar (GPR) can explore the ground subsurface rapidly with relatively low cost compared to other exploration methods. However, the exploration data obtained from GPR requires considerable experiences because interpretation is not intuitive. Recently, researches on automated detection technology for GPR data using deep learning have been conducted. However, the lack of GPR data which is essential for training makes it difficult to build up the reliable detection model. To overcome this problem, we conducted a preliminary study to improve the performance of the detection model using finite difference time domain (FDTD)-based numerical analysis. Firstly, numerical analysis was performed with homogeneous soil media having single permittivity. In case of heterogeneous ground, numerical analysis was performed considering the ground heterogeneity using fractal technique. Secondly, deep learning was carried out using convolutional neural network. Detection Model-A is trained with data set obtained from homogeneous ground. And, detection Model-B is trained with data set obtained from homogeneous ground and heterogeneous ground. As a result, it is found that the detection Model-B which is trained including heterogeneous ground shows better performance than detection Model-A. It indicates the ground heterogeneity should be considered to increase the performance of automated detection model for GPR exploration.

• Structural Engineering and Mechanics
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• v.63 no.6
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• pp.751-760
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• 2017

In recent years, multifractal-based analysis methods have been widely applied in engineering. Among these methods, multifractal detrended cross-correlation analysis (MFDXA), a branch of fractal analysis, has been successfully applied in the fields of finance and biomedicine. For its great potential in reflecting the subtle characteristic among signals, a structural health monitoring (SHM) system based on MFDXA is proposed. In this system, damage assessment is conducted by exploiting the concept of multifractal theory to quantify the complexity of the vibration signal measured from a structure. According to the proposed algorithm, the damage condition is first distinguished by multifractal detrended fluctuation analysis. Subsequently, the relationship between the q-order, q-order detrended covariance, and length of segment is further explored. The dissimilarity between damaged and undamaged cases is visualized on contour diagrams, and the damage location can thus be detected using signals measured from different floors. Moreover, a damage index is proposed to efficiently enhance the SHM process. A seven-story benchmark structure, located at the National Center for Research on Earthquake Engineering (NCREE), was employed for an experimental verification to demonstrate the performance of the proposed SHM algorithm. According to the results, the damage condition and orientation could be correctly identified using the MFDXA algorithm and the proposed damage index. Since only the ambient vibration signal is required along with a set of initial reference measurements, the proposed SHM system can provide a lower cost, efficient, and reliable monitoring process.

• Journal of the Korean Mathematical Society
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• v.41 no.6
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• pp.945-955
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• 2004

In this paper, we establish a number system in $R^n$ which arises from a Haar wavelet basis in connection with decompositions of certain Cuntz algebra representations on $L^2$( $R^n$). Number systems in $R^n$ are also of independent interest [9]. We study radix-representations of $\chi$ $\in$ $R^n$: $\chi$:$\alpha$$_{ι}$ $\alpha$$_{ι-1}$…$\alpha$$_1$$\alpha$$_{0}$ ㆍ$\alpha$$_{-1}$ $\alpha$$_{-2}$ … as $\chi$= $M^{ι}$$\alpha$$_{ι}$ $\alpha$＋…M$\alpha$$_1$＋$\alpha$$_{0}$ ＋ $M^{-1}$ $\alpha$$_{-1}$ ＋ $M^{-2}$ $\alpha$$_{-2}$ ＋… where each $\alpha$$_{k}$ $\in$ D, and D is some specified digit set. Our analysis uses iteration techniques of a number-theoretic flavor. The view-point is a dual one which we term fractals in the large vs. fractals in the small,illustrating the number theory of integral lattice points vs. fractions.s vs. fractions.