• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.405-406
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• 2006

Raw materials from different sources, produced by a given process and having equal chemical composition, are supposed to be equivalent. The differences in sintering behavior have been investigated on P/M steels obtained from four diffusion-bonded powders (Fe + Ni + Cu + Mo) on atomized iron base, at the same alloy contents. Two levels of carbon and two sintering conditions have been investigated. Dimensional changes, C content, hardness, microhardness pattern, universal hardness, fractal analysis, pore features, microstructure features, and rupture strength have been compared to characterize different raw materials. The results show that the claimed equivalence is not confirmed by experimental data.

• Imaging Science in Dentistry
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• 제50권1호
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• pp.31-36
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• 2020

Purpose: The purpose of this study was to investigate the impact of radiotherapy on mandibular bone tissue in head and neck cancer patients through an analysis of pixel intensity and fractal dimension values on digital panoramic radiographs. Materials and Methods: Thirty patients with radiographic records from before and after 3-dimensional (3D) conformational radiotherapy were selected. A single examiner carried out digital analyses of pixel intensity values and fractal dimensions, with the areas of interest unilaterally located in the right angle medullary region of the mandible below the mandibular canal and posterior to the molar region. Results: Statistically significant decreases were observed in the mean pixel intensity (P=0.0368) and fractal dimension (P=0.0495) values after radiotherapy. Conclusion: The results suggest that 3D conformational radiotherapy for head and neck cancer negatively affected the trabecular microarchitecture and mandibular bone mass.

• 대한기계학회논문집B
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• 제23권9호
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• pp.1139-1150
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• 1999

The evolution of silica aggregate particles in coflow diffusion flames has been studied experimentally using light scattering and thermophoretic sampling techniques. The measurements of scattering cross section from $90^{\circ}$ light scattering have been utilized to calculate the aggregate number density and volume fraction using with combination of measuring the particle size and morphology through the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh-Debye-Gans and Mie theory for fractal aggregates and spherical particles, respectively. Of particular interests are the effects of flame temperature on the evolution of silica aggregate particles. As the flow rate of $H_2$ increases, the primary particle diameters of silica aggregates have been first decreased, but, further increase of $H_2$ flow rate causes the diameter of primary particles to increase and for sufficiently larger flow rates, the fractal aggregates finally become spherical particles. The variation of primary particle size along the upward jet centerline and the effect of burner configuration have also been studied.

• Geomechanics and Engineering
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• 제3권3호
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• pp.219-231
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• 2011

Waste fills resulting from coal mining should consist of large, free-draining sedimentary rocks fragments. The successful performance of these fills is related to the strength and durability of the individual rock fragments. When fills are made of shale fragments, some fragments will be durable and some will degrade into soil particles resulting from slaking and inter-particle point loads. The degraded material fills the voids between the intact fragments, and results in settlement. A laboratory program with point load and slake durability tests as well as thin section examination of sixty-eight shale samples from the Appalachian region of the United States revealed that pore micro-geometry has a major influence on degradation. Under saturated and unsaturated conditions, the shales absorb water, and the air in their pores is compressed, breaking the shales. This breakage was more pronounced in shales with smooth pore boundaries and having a diameter equal to or smaller than 0.060 mm. If the pore walls were rough, the air-pressure breaking mechanism was not effective. However, pore roughness (measured by the fractal dimension) had a detrimental effect on point load resistance. This study indicated that the optimum shales to resist both slaking as well as point loads are those that have pores with a fractal dimension equal to 1.425 and a diameter equal to or smaller than 0.06 mm.

• 지질공학
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• 제9권2호
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• pp.119-134
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• 1999

모량단층 주변에 발달하고 있는 절리의 분포상태를 알아보기 위해 횡단법(橫斷法)과 재고법(在庫法)을 이용하여 절리의 배향, 간격, 밀도 등을 조사하였다. 횡단법에 의한 조사에 의하면 연구지역에서 가장 우세방향의 절리조는 NNE와 EW방향으로 나타나며, 이들 절리들의 간격분포는 단층의 중심부에서 음의 지수분포, 단층에서 먼 지점에서 대수-정규 분포를 보여준다. 재고법의 조사결과에 의하면 각 절리도(節理圖)상에서 우세한 절리조의 방향은 NW와 NE방향이며, 절리밀도는 단층의 중심부로 가까워질 수록 높게 나타난다. 또한 연구지역에서 발달하고 있는 절리망에 대해 박스카운팅법과 캔터의 먼지법을 이용하여 프랙탈 차원을 구하여 정량화시키고 단층주변에서의 분포양상을 살펴보았다. 박스카운팅법에 의해 구한 프랙탈 차원은 1.31~l.70의 범위를 보여주며, 단층의 중심부에 가까워질수록 높게 나타난다. 그리고 박스카운팅법에 의해 구한 프랙탈 차원과 절리밀도를 비교해보면 이들은 서로 비례 관계에 있으나 프랙탈 차원은 동일 밀도지역에서 절리의 분포상태에 따라 달라질 수 있다. 캔터의 먼지법에 의해 구한 프랙탈 차원은 설치하는 측선의 방향에 따라 다양하게 나타나며 이는 절리의 분포가 이방성을 나타냄을 보여준다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 춘계총회 및 학술발표회
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• pp.53-53
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• 2005

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2004년도 춘계총회 및 학술발표회
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• pp.55-55
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• 2004

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 추계총회 및 학술발표회
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• pp.65-65
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• 2003

• 감성과학
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• 제14권3호
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• pp.403-414
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• 2011

본 연구에서는 객관적인 아름다움에 대한 주관적인 미적 경험으로서의 인지적, 감정적 경험에 관여하는 뇌 활성화 과정을 기능적 자기공명영상을 이용하여 검토해 보았다. 우선, 프랙탈 이미지에 대한 미적평가 행동과 제로 보편적인 아름다움의 준거를 확인하였다. 평정 결과에 기초하여, 전체 270개 이미지 중 가장 점수가 높은 50개를 아름다운 이미지로, 점수가 낮은 50개를 아름답지 않은 이미지로 선정하였다. 두 가지 조건을 블록으로 제시한 신경영상 연구 결과, 아름답다고 평가한 이미지에 대해서는 미적 경험에 관여하는 인지적, 정서적 처리에 관여된 부위인 전두엽과 대상회와 뇌섬엽이 활성화되었으며, 아름답지 않다고 평가한 이미지에 대해서는 부정적인 정서와 관련된 중후두회와 전설소엽의 활성화가 관찰되었다. 아름다움 평가에 대한 조건별 접속분석의 결과, 미적평가가 긍정적인 이미지에 대해서는 측두엽의 활성화가, 부정적인 이미지에 대해서는 두정엽의 활성화가 특징적으로 나타났다. 이에 대해 의미론적 해석과 추상화 과정과 연결하여 논의하였다.

• 대한한의진단학회지
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• 제11권2호
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• pp.84-95
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• 2007

Background and Purpose: We have studied the trends of EEG signals in the voluntary breathing condition by applying the fractal analysis. According to chaos theory, irregularity of EEG signals can result from low dimensional deterministic chaos. A principal parameter to quantify the degree of Chaotic nonlinear dynamics is correlation dimension. The aim of this study was to analyze correlation between the correlation dimension of EEG and HRV(heart rate variability). We have studied the trends of EEG signals in the voluntary breathing condition by applying the fractal analysis. Methods: EEG raw data were measured by moving windows during 15 minutes. Then, the correlation dimension(D2) was calculated by each 40-seconds-segment in 15 minutes data, totally 36 segments. 8 channels EEG study on the Fp, F, T, P was carried out in 30 subjects. Results and Conclusion: Correlation analysis of HRV was calculated with deterministic non-linear data and stochastic non-linear data. 1. Ch1(Fp1), Ch4(F3), Ch4(F4) is positive correlated with In LF. 2. Ch1(Fp1), Ch3(F3) is positive correlated with In TF.