• Korean Journal of Optics and Photonics
• /
• v.3 no.3
• /
• pp.167-171
• /
• 1992

We present the static and dynamic light scattering results of the salt induced restructured colloidal silica aggregates. We also report the results from the transmission electron micrographs which confirms the individual sizes of the particles and the local structure of the ramified aggregates. The fractal dimensions of the restructuring silica aggregates are considerably different with in-situ light scattering measurements. The measured fractal dimensions, $D_{F}$, is 2.21 for the 0.5 wt.% concentration of the salt induced Ludox-AM. The Rayleigh linewidth for 0.1 wt.% concentration of Ludox-AM is discussed.

• The Journal of the Korea Contents Association
• /
• v.17 no.1
• /
• pp.465-474
• /
• 2017

This study aimed to identify the trends of related research as a basic study for the development of creative convergent formative education program of natural structure concept. This study sought to identify research trends present in previous studies. The nature structure of the preliminary research was limited to the three concepts: (i) fractal ; (ii) kinetic and (iii) biomimicry. In this study, the trends of domestic research in the last 10 years related to the concept of natural structure were analyzed using academic research information service. It was found that, to date, little research has been conducted on the three concepts across education fields. In relation to the fractal concept, previous research has focused on mathematics. This preliminary study sought to review the abovementioned three concepts or the development of a modeling education program. It should be significant, if an education program adopted unlimited modeling principles to understand the innate features of the nature structure. However, very few education programs have adopted the three concepts of the nature structure. Future studies would seek to review international research trends based on the three concepts of the nature structure and combine the results on international research trends with the results on domestic research trends found in this study.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.10
• /
• pp.1177-1183
• /
• 2010

In this paper, design of a microstrip-fed, Spidron fractal-shaped slot antenna with circular polarization is represented. The ground plane of the designed antenna has a slot that comprises seven right-angled triangle next to each other in a low. A reflector is placed at the bottom on microstrip feeding line to enhance the antenna gain. The optimized design was conducted by varying a length of the first right-angled triangle, location of feeding line, space between a substrate and a reflector. The proposed antenna was fabricated on a Taconic-RF35 substrate. The entire dimension of the fabricated antenna is $40{\times}40{\times}18.6mm^3$ and the reflector is 18.6 mm away from the ground plane. The measured gain of the fabricated antenna is 6.7 dBi at 4.3 GHz. The measured bandwidths of -10 dB reflection and 3 dB axial ratio are 41 % and 7.4 %, respectively.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1389-1390
• /
• 2008

In this paper, a This paper presents the Hilbert curve Fractal Antenna has properties of Self-similarity and Plane-Filling. In case of fractal antenna is very useful to be small and multiple resonant. The antenna has a resonant frequency of 910MHz and 2450MHz base on RFID(Radio Frequency IDentification). In particular, we designed tag antenna by the $4^{th}$ repeat. According to the repeated number of fractal structures, resonance frequency became looking downward. Theses presented Frequency, Such as 910MHz and 2450MHz, at $S_{11}$ is -31dB and -19dB, bandwidth 120MHz and 90MHz to VSWR 2:1.

• Journal of the Mineralogical Society of Korea
• /
• v.22 no.4
• /
• pp.313-324
• /
• 2009

We explore the effect of particle shape and size on 3-dimensional (3D) network and pore structure of porous earth materials composed of glass beads and silica gel using NMR micro-imaging in order to gain better insights into relationship between structure and the corresponding hydrologic and seismological properties. The 3D micro-imaging data for the model porous networks show that the specific surface area, porosity, and permeability range from 2.5 to $9.6\;mm^2/mm^3$, from 0.21 to 0.38, and from 11.6 to 892.3 D (Darcy), respectively, which are typical values for unconsolidated sands. The relationships among specific surface area, porosity, and permeability of the porous media are relatively well explained with the Kozeny equation. Cube counting fractal dimension analysis shows that fractal dimension increases from ~2.5－2.6 to 3.0 with increasing specific surface area from 2.5 to $9.6\;mm^2/mm^3$, with the data also suggesting the effect of porosity. Specific surface area, porosity, permeability, and cube counting fractal dimension for the natural mongolian sandstone are $0.33\;mm^2/mm^3$, 0.017, 30.9 mD, and 1.59, respectively. The current results highlight that NMR micro-imaging, together with detailed statistical analyses can be useful to characterize 3D pore structures of various porous earth materials and be potentially effective in accounting for transport properties and seismic wave velocity and attenuation of diverse porous media in earth crust and interiors.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.10
• /
• pp.6551-6557
• /
• 2015

This paper discusses the surface roughness of corroded reinforcement rebar-in-coil focusing on the quantitative measurement technique using 3D scanner. Reinforcement rebar-in-coil was stacked in site for 0 day, 3 days, 7 days, 14 days and 21 days. And rebar-in-coil was corroded 0.04%, 0.3367%, 0.6157%, 0.7898%, and 1.1965% respectively. Using 3-dimensional scanner, each surface profile of reinforcement rebar-in-coil was established, and surface roughness was measured. Through the tests and analyses of corroded rebar-in-coil, the increase of fractal dimension for each rebar-in-coil was measured as 0.0216, 0.0235, 0.028, 0.0319, and 0.0455 for different stacked periods. Therefore, surface assessment technique using fractal dimension showed similar results with the actual corrosion rate.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.4-4
• /
• 2015

기압 분포의 공간 구조를 이해하고, 그것의 변동을 살펴보는 것은 풍속의 경향을 파악하는 것은 물론, 장기적인 측면에서는 기후변화를 예측하기 위한 기본 과정이라 할 수 있다. 본 연구에서는 장기간에 걸쳐 공간적으로 연속적인 관찰이 가능한 20CR(20th Century Reanalysis) 원격탐사 재분석 자료의 지오포텐셜(geopotential) 값을 활용하여 동아시아 지역 기압의 공간 분포를 살펴보았다. 그 결과 특정 범위 내에서 계산되는 기압의 편차 값과 해당 범위를 정의하는 수평 거리 사이의 관계(변동도; variogram)가 멱함수를 따르는 것을 확인하였다. 흥미로운 점은 지난 반세기 동안 멱함수의 계수 값이 풍속과 동일한 패턴으로 변화하는 반면, 지수 값 (프랙탈 차원)은 일정하게 유지되고 있다는 사실이다. 또한, 2000년 이후로는 계절 별로 한랭한 기단 (겨울철)과 온난한 기단 (여름철)이 번갈아가며 동아시아 지역으로 세력을 확장하는 경향을 보였으며, 그로인해 전반적인 기압의 편차가 증가하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.43-46
• /
• 2000

In this study, (Ba, Sr)$TiO_3$ (BST) ceramics thin films were prepared by Sol-Gel method. BST solution was made and spin-coated on Pt/$TiO_2$/Si substrate at 4000 [rpm] for 10 seconds. Coated specimens were dried at 150[$^{\circ}C$] for 5 minutes. Coating process was repeated 3 times and then sintered at 750[$^{\circ}C$] for 30 minutes. Structure and electrical characteristics of specimen was analyzed by Fractal Process. Thickness of BST ceramics thin films are about 2800[$\AA$]. Dielectric constant and loss of thin films was little decreased at 1[kHz]~1[MHz]. Dielectric constant and loss to frequency were 250 and 0.02 in BST3. The property of leakage current as the relation between the current and the voltage was that change of the leakage current was stable when the applied voltage was 0~3[V].

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.11
• /
• pp.234-242
• /
• 1999

In this paper, a method for assessment of the anisotropic machined surfaces is proposed. Fractal dimension (FD) is calculated using structure function and an index of the anisotropy is obtained as a ratio of its maximum and minimum value. The upper limit of fractal region on the structure function is determined as the length of the lag where the autocorrelation function shows 20% of its maximum value. The model of the structure function is derived from that of the auto correlation function. And, it shows that the new method and the proposed index of anisotropy are useful.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.2
• /
• pp.121-129
• /
• 2008

In this paper, we present a fast analysis of multilayer microstrip fractal structure by using the fast multipole method (FMM). In the analysis, accurate spatial green's functions from the real-axis integration method(RAIM) are employed to solve the mixed potential integral equation(MPIE) with FMM algorithm. MoM's iteration and memory requirement is $O(N^2)$ in case of calculation using the green function. the problem is the unknown number N can be extremely large for calculation of large scale objects and high accuracy. To improve these problem is fast algorithm FMM. FMM use the addition theorem of green function. So, it reduce the complexity of a matrix-vector multiplication and reduce the cost of calculation to the order of $O(N^{1.5})$, The efficiency is proved from comparing calculation results of the moment method and Fast algorithm.