• 치과방사선
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• 제29권1호
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• pp.203-208
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• 1999

Purpose: This study was to investigate the age and sex differences of the fractal dimension of the normal parotid glands in the digitized CT images. Materials and methods: The six groups. which were composed of 42 men and women from 20 s. 40' sand 60' s and over were picked. Each group contained seven people of the same sex. The normal parotid CT images were digitized. and their fractal dimensions were calculated using Scion Image PC program. Results: The mean of fractal dimensions in males was 1.7292(±0.0588) and 1.6329(±0.0425) in females. The mean of fractal dimensions was 1.7617. in young males 1.7328 in middle males, and 1.6933 in old males. The mean of fractal dimensions was 1.6318. in young females 1.6365 in middle females. and 1.6303 in old females. There was no statistical difference in fractal dimension between left and right parotid gland of the same subject(P>0.05). Fractal dimensions in male were decreased in older group(P<0.05) and larger than female in same age group(P<0.05). But fractal dimensions in female had a tendency to decrease in older group but no statistical difference between ages(P>0.05). Conclusions: The fractal dimension of parotid glands in the digitized CT images will be useful to evaluate the age and sex differences.

• 한국안전학회지
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• 제17권4호
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• pp.38-44
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• 2002

The application of fractal concept provides an useful method in the study for the quantitative analysis of irregular variations like the fracture surfaces and crack profiles. Fractal curves have characteristics that represents a self-similarity based on the fractal dimension. The fractal dimensions were obtained by the box counting method. In this report, we obtained the nearly stable fractal dimensions of fracture crack profiles for STS316 with CT specimen as the crack advances and the relationships between crack length and fractal dimension. Moreover fractal fracture parameter that corresponds to J-R curve is shown by the relationships between fractal dimension and crack extension. From the results, we concluded that crack extension of high toughness material also shows the fractal characteristics, which can be used in order to evaluate the crack life precisely.

• Imaging Science in Dentistry
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• 제38권3호
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• pp.147-151
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• 2008

Purpose : The purpose of this study was to investigate whether fractal analysis of periapical and panoramic radiographs was useful in predicting osteoporosis risk. Materials and Methods : 37 postmenoposal women between the age of 42 and 79 were classified as normal and osteoporosis group according to the bone mineral density of lumbar vertebrae and periapical and panoramic radio-graphs were taken. Fractal dimensions at periapical areas of mandibular first molars were calculated to differentiate the two groups. Results : The mean fractal dimensions of normal group on periapical and panoramic radiographs were $1.413{\pm}0.079$, $1.517{\pm}0.071$ each. The mean fractal dimensions of osteoporotic group on periapical and panoramic radiographs were $1.498{\pm}0.086$, $1.388{\pm}0.083$ each. The mean fractal dimension from peripaical radiographs of osteoporotic group was statistically significantly higher than that of normal group. The mean fractal dimension from panoramic radiographs of osteoporotic group was statistically significantly lower than that of normal group. Conclusion : Fractal analysis using periapical and panoramic radiographs was useful in predicting osteoporosis.

• 한국입자에어로졸학회지
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• 제11권4호
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• pp.99-105
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• 2015

The possible existence forms of particle aggregates in liquid medium are classified into four different types according to their morphological characteristics, including the single particles that are separated from each other, the linear aggregates in which all component particles are located in a line, the planar aggregates where all particles are arranged on a plane, and the volumetric aggregates where all particles forms a three-dimensional space. These particle aggregates with different space morphologies have different fractal dimensions and different influence on the rheological phenomena of the solid-liquid system. The effects of various aggregates on the suspension viscosity are analyzed and related with the particle concentration, and then a mathematical model is presented to determine the fractal dimensions of various aggregates by measuring the apparent viscosity of the solid-liquid system. In the model, the viscous fractal dimension is developed as a new concept, the fractal dimensions of different aggregates can be obtained separately and then the relative components of various aggregates experimentally analyzed.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.1-9
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• 2002

Simultaneous PIV and OH PLIF measurements are used for shear strain rates and flame locations, respectively. It is believed that the shear strain rates represent flow characteristics such as turbulence intensity and the OH intensity indicates the flame characteristics such as burning velocities. However, these are still lack of geometric information, which may be very important to flame quenching Hence, fractal dimensions 'Df) of the OH images are adopted as an additional information. Finally, the flame structure diagram proposed in this research has three parameters, which consist of strain rates, OH intensities and fractal dimensions. The results show that this diagram classifies turbulent premixed flames more effectively based on flame structures. The regime of weak turbulence is limited to narrow strain ranges and has the fractal dimension of about 2 In the regime of moderate turbulence, OH intensities increase as strain rates increase and the values of fractal dimensions are 1.8 Df 1.95. The regimes of thickened reaction and flame extinction (quenching) show bell-shaped and their values of fractal dimensions are 1.5 Df 1.7 and 0.9 Df 0.6, respectively.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권5호
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• pp.494-498
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• 2007

Purpose: This study was done to know the usefulness of fractal analysis when evaluating the radiologic changes after decompression on jaw bone cystic lesions using fractal analysis. Materials and methods: 30cases of cystic lesions were followed up after decompression. Panoramic image was used to observe radiologic changes around the cystic lesion. The part of the panoramic image which showed radiologic change was defined as region of interest(ROI); The fractal dimension of the ROI was calculated using box-counting method. Results: Using sign-rank test, there was a statistically significant difference in fractal dimensions after decompression therapy(P<0.0001). The fractal dimensions statistically increased after decompression(the median of D:0.12). Conclusions: The ROI after decompression showed higher fractal dimensions which offer the objective proof of the bone healing around cystic lesions after decompression treatment.

• 한국공작기계학회논문집
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• 제11권1호
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• pp.77-82
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• 2002

It is known that fractal theory has recently been used as a useful in the characterization of surface texture and the understanding of tribological phenomena such as friction wear and lubrication The fractal based method for describing the rubbed surface texture has aroused great interest In this paper the fractal descriptors was applied to rubbed surface of hydraulic driving material with image processing system in order to describe morphology of the rubbed surface The results showed that the fractal dimension can be determined by sum of intensity difference of surface pixel. The two step size to get fractal dimension is similar to surface roughness Ra. Fractal dimensions of the rubbed surfaces increase with an increase of applied load Morphology of the rubbed surface driving in lubricant can be effectively obtained by fractal dimensions.

• 대한화장품학회지
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• 제26권1호
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• pp.261-274
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• 2000

당류계 계면활성제인 sucrose distearate(S110), sucrose monostearate(S160), POE(20) ethyl glucose stearate(SSE20)과 오일성분인 알칸 계열의 탄화수소 hexane( $C_{6}$), decane( $C_{10}$), tetradecane( $C_{l4}$), octadecane( $C_{8}$)과 squalane (SQ) , liquid paraffin(LP) , octylpalminate(OP) , octylstearate(OS), alkylbenzoate(AB), isostearylbenzoate(ISB)를 사용하여 에멀젼을 제조하였으며 에멀젼 입자의 구조 형태는 광산란법을 이용하여 fractal 차원으로 나타내었다. 에멀젼 입자의 fractal 차원은 오일의 농도 및 탄소수와 오일의 비극성이 증가함에 따라 크게 나타났다. fractal 차원은 대부분 1.7~2.8으로 입자의 구조 형태는 fractal 구조를 이루고 있으나, S110계와 S160계의 Cla 50, LP의 fractal 차원은 3.0~3.2으로 내부 구조가 비교적 조밀한 회합체 구조를 형성하였다. S160계와 S110계의 fractal 차원은 2.I~2.6으로 서로 비슷한 fractal 구조를 형성하며, SSE20의 fractal 차원는 1.5~2.1으로 S160계 및 S110계 보다 덜 조밀한 회합체 구조를 이루는 것으로 나타났다. 입자의 구조 형태는 오일과 계면활성제의 종류에 영향을 받으며 계면활성제의 친수부가 동일하면 비슷한 구조를 형성하였으며 S160의 친수부 구조인 sucrose보다 SSE20의 polyoxyethylene group에 의한 장애효과가 더욱 크게 나타났다.다..

• 한국실내디자인학회논문집
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• 제23권1호
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• pp.88-95
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• 2014

This study intended arousal of other viewpoints that deal with and understand spaces and shapes, by describing the concept of 'dimensions' into visual patterns. Above all, the core concept of spatial dimensions was defined as 'expandability'. Then, first, the 'golden ratio', 'Fibonacci sequence', and 'fractal theory' were defined as elements of each dimension by stage. Second, a 'unit cell' of one dimension as 'minimum unit particles' was set. Next, Fibonacci sequence was set as an extended concept into two dimensions. Expansion into three dimensions was applied to the concept of 'self-similarity repetition' of 'Fractal'. In 'fractal dimension', the concept of 'regularity of irregularity' was set as a core attribute. Plus, Platonic solids were applied as a background concept of the setting of the 'unit cell' from the viewpoint of 'minimum unit particles'. Third, while 'characteristic patterns' which are shown in the courses of 'expansion' of each dimension were embodied for the visual expression forms of dimensions, expansion forms of dimensions are based on the premise of volume, directional nature, and concept of axes. Expressed shapes of each dimension are shown into visually diverse patterns and unexpected formative aspects, along with the expression of relative blank spaces originated from dualism. On the basis of these results, the 'unit cell' that is set as a concept of theoretical factor can be defined as a minimum factor of a basic algorism caused by other purpose. In here, by applying diverse pattern types, the fact that meaning spaces, shapes, and dimensions can be extracted was suggested.

• 한국습지학회지
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• 제5권1호
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• pp.15-27
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• 2003

The fractal study in river basin has been performed for the sinuosity of an individual stream and bifurcation of the stream network. The previous studies has suggested many methods or equations for the fractal dimension estimation in a river network. This study used those many equations for the estimation of fractal dimensions on the streams such as Bokha, Gonjiam, and Pocheon streams. The estimated dimensions are in the range of 1 to 1.359 for the individual stream and 1.634 to 2 for the stream network. The most of equations were suggested based on the assumption of self-similarity of a river basin for the individual stream and stream network. However, the real river basin could be characterized by self-affinity rather than self-similarity. Even though we estimate the dimensions by using many equations, we could not recommend which one is better equation for the estimation of fractal dimension. This might be from the self-similarity assumption of equations. Therefore, the assumption and research work of self-affinity will be needed for the appropriate estimation of fractal dimension in river basin.