• 치과방사선
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• 제28권2호
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• pp.339-353
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• 1998

The purpose of this study was to investigate whether a radiographic estimate of osseous fractal dimension and power spectrum of 2D discrete Fourier transform is useful in the characterization of structural changes in bone. Ten specimens of bone were decalcified in fresh 50 ml solutions of 0.1 N hydrochloric acid solution at cummulative timed periods of 0 and 90 minutes. and radiographed from 0 degree projection angle controlled by intraoral parelleling device. I performed one-dimensional variance. fractal analysis of bony profiles and 2D discrete Fourier transform. The results of this study indicate that variance and fractal dimension of scan line pixel intensities decreased significantly in decalcified groups but Fourier spectral analysis didn't discriminate well between control and decalcified specimens.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.755-759
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• 2000

The determination of surface topography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe topography of various frictional surface. the wear test was carried out under different experimental conditions in dry friction. And fractal descriptors was applied to frictional surface of laser modified steel with image processing System. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Topography of frictional surface can be effectively obtained by fractal dimensions.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.23-28
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• 2000

The determination of surface morphology is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe morphology of various rubbed surface, the wear test was carried out under different experimental conditions in lubricating wear. And fractal descriptors was applied to rubbed surface of hydraulic driving material with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Morphology of rubbed surface can be effectively obtained by fractal dimensions.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.1124-1128
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• 2005

In this paper, a plan-coordination architecture is proposed for multi-agent control in the fractal manufacturing system (FrMS). A fractal in FrMS is a set of distributed agents whose goal can be achieved through cooperation, coordination, and negotiation with other agents. Since each agent in the FrMS generates, achieves, and modifies its own plan fragments autonomously during the coordination process with other agents, it is necessary to develop a systematic methodology for the achievement of global plan in the manufacturing system. The heterarchical structure of the FrMS provides a compromised plan-coordination approach, it compromise a centralized plan-generation/execution (which mainly focuses on the maximization of throughput) with a distributed one (which focuses on the autonomy of each module and flexibility of the whole system). Plan-coordinators in lower level fractal independently generate plan fragments according to the global plan of higher level fractal, and plan-coordinators in higher level fractal mediate/coordinate the plan fragments to enhance the global performance of the system. This paper assumes that generation method of the plan fragments and the negotiation policy of the fractal is achieved by a simple process, and we mainly focuses on the information exchanging and distributed decision making process to coordinate the combinations of plan fragments within a limited exchange of information.

• 한국물환경학회지
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• 제16권4호
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• pp.459-468
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• 2000

This study is to investigate the floc structure and removal of turbidity and organic matter by PACI coagulation. The turbidity removal by PACI coagulation was obtained at larger pH range than alum coagulation. And the removal of organic matter was obtained at smaller pH range than that of turbidity. The organic matter was removed by the adsorption of $Al(OH)_3$ precipitates. Floc structure was characterized by measuring fractal dimension and volume diameter using AIA and SALLS. Fractal dimension measured by AIA did not show the different characteristics of floc produced in sweep floe and charge neutralization region. Using SALLS, floes in sweep floc region were found to be larger size and fractal dimension than flocs in charge neutralization region. As pollutant removal increased. larger fractal dimension and size of floc were measured. SALLS method was found to be more useful method to characterize flocs in coagulation than AIA method.

• Structural Engineering and Mechanics
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• 제41권5호
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• pp.663-673
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• 2012

A number of mode shape-based structure damage identification methods have been verified by numerical simulations or experiments for on-line structure health monitoring (SHM). However, many of them need a baseline mode shape generated by the healthy structure serving as a reference to identify damages. Otherwise these methods can hardly perform well when multiple cracks conditions occur. So it is important to solve the problems above. By aid of the fractal dimension method (FD), Qiao and Wang proposed a generalized fractal dimension (GFD) to detect the delamination damage. As a modification of GFD, Qiao and Cao proposed the approximate waveform capacity dimension (AWCD) technique to simplify the calculation of fractal and overcome the false peak appearing in the high mode shapes. Based on their valued work, this paper combined and applied the AWCD method and curvature mode shape data to detect multiple damages in beam. In the end, the identification properties of the AWCD for multiple damages have been verified by groups of Monte Carlo simulations and experiments.

• 한국전자파학회논문지
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• 제20권3호
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• pp.215-221
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• 2009

본 논문에서는 차량 GPS 안테나로 사용할 수 있는 프랙털 구조의 사다리꼴 마이크로스트립 패치 안테나를 설계하고 이를 제작하였다. 기판 손실을 없애고 이득을 향상시키기 위하여 공기층을 갖는 패치 안테나로 설계하였다. 사다리꼴 패치에 프랙털 구조의 적용과 슬롯의 부설로 일반 삼각형 패치 안테나 면적 대비 42.5 %크기로 소형화시켰다. 제작 후 측정한 결과, VSWR 2:1 기준으로 GPS 대역을 포함한 200 MHz의 대역폭을 얻었다. 이득은 공진주파수에서 4.31 dBi로 일반 세라믹 패치 안테나의 이득보다 GPS 대역에서 2$\sim$5 dB 높은 이득을 얻었다.

• 대한환경공학회지
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• 제22권7호
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• pp.1263-1271
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• 2000

Alum을 이용한 응집 과정에서 탁도 및 유기물 제거와 응집 floc의 특성을 파악하였다. 본 실험에서 구한 탁도 제거영역을 Amitharajah의 연구결과와 비교했을 때 sweep floc 및 charge neutralization의 제거영역이 낮은 pH 영역으로 이동하였는데 그 원인은 원수에 포함된 유기물 농도가 다른데서 찾을 수 있다. 대체적으로 탁도 및 유기물($UV_{254}$와 TOC)의 제거영역은 비슷하였으나 탁도 제거에 비해 낮은 pH에서 유기물 제거의 효과가 높았다. Floc의 특성은 AIA, SALLS 방법을 이용하여 volume diameter과 fractal dimension을 측정하였다. AIA 방법에 비해 SALLS 방법의 측정이 용이하고 신뢰성도 높았다. SALLS 방법을 이용하여 floc을 측정한 결과 sweep floc 영역의 floc이 charge neutralization 영역의 floc 보다 fractal dimension과 평균 직경이 크게 측정되었으며, 오염물질의 제거율이 높을수록 floc의 fractal dimension과 평균 직경도 크게 나타났다.

• Journal of Electrical Engineering and Technology
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• 제6권3호
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• pp.391-396
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• 2011

The tracking pattern formed on the dielectric surface due to a surface electrical discharge exhibits fractal structure. In order to quantitatively investigate the fractal characteristics of the surface tracking pattern, the dielectric breakdown model has been employed to numerically generate the surface tracking pattern. In dielectric breakdown model, the pattern growth is determined stochastically by a probability function depending on the local electric potential difference. For the computation of the electric potential for all points of the lattice, a two-dimensional discrete Laplace equation is solved by mean of the successive over-relaxation method combined to the Gauss-Seidel method. The box counting method has been used to calculate the fractal dimensions of the simulated patterns with various exponent $\eta$ and breakdown voltage $\phi_b$. As a result of the simulation, it is found that the fractal nature of the surface tracking pattern depends strongly on $\eta$ and $\phi_b$.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.404-409
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• 2000

The determination of surface morphology is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe morphology of various rubbed surface, the wear test was carried out under different experimental conditions in lubricating wear. And fractal descriptors was applied to rubbed surface of hydraulic driving material with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Morphology of rubbed surface can be effectively obtained by fractal dimensions.