• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.234.2-234.2
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• 2015

Recently, the electromagnetically-induced transparency (EIT)-like effect in metamaterials has attracted enormous interest. Metamaterial analogs of EIT enable promising applications in slow-light devices, low-loss metamaterial, quantum optics, and novel sensors. In this work, we experimentally and numerically studied a bilayer metamaterial for controllable EIT-like spectral response at microwave frequencies. Bilayer metamaterial consists of two snake-shape resonators (SSRs) with one and two bars. The transmission spectra were measured in a frequency range of 4 - 8 GHz in an anechoic chamber at normal incidence. It is found that two SSRs in the metamaterial are activated in bright modes, and the coupling between two bright modes leads to the EIT-like effect, which results in the enhanced transmission at 5.61 GHz. Furthermore, we confirm that the EIT-like feature could be controlled by adjusting the geometric parameters of metamaterial structure. Our work provides a way to tunable EIT-like effect and various potential applications including filters, sensors, and other microwave devices.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.12
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• pp.3329-3343
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• 1995

The interaction of mixed convection and surface radiation in a printed circuit board(PCB) is investigated numerically. The electronic equipment is modeled by a two-dimensional channel with three hot blocks. In order to calculate the turbulent flow characteristics, the low Reynolds number k-.epsilon. model which is proposed by Launder and Sharma is applied. The S-4 approximation is used to solve the radiative transfer equation. The effects of the Reynolds number and geometric configuration variation of PCB on the flow and heat transfer characteristics are analyzed. As the results of this study, it is found that the thermal boundary layer occured at adiabatic wall in case with thermal radiation included, and the effect of radiation is also found to be insignificant for high Reynolds numbers. It is found, as well, that the heat transfer increases as the Reynolds number and block space increase and the channel height decreases and the heat transfer of vertical channel is greater than that of horizontal channel.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1510-1517
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• 1995

A theoretical method is described to simulate the propagation of turbulent premixed flames in a closed vessel. The objective is to develop and test an efficient technique to predict the propagation speed of flame as well as the geometric structure of the flame surfaces. Flame is advected by the statistically generated turbulent flow field and propagates as a wave by solving twodimensional Hamilton-Jacobi equation. In the simulation of the unburned gas flow field, following turbulence properties were satisfied: mean velocity field, turbulence intensities, spatial and temporal correlations of velocity fluctuations. It is assumed that these properties are not affected by the expansion of the burned gas region. Predictions were compared with existing experimental data for flames propagating in a closed vessel charged with hydrogen/air mixture with various turbulence intensities and Reynolds numbers. Comparisons were made in flame radius growth rate, rms flame radius fluctuations, and average perimeter and fractal dimensions of the flame boundaries. Two dimensional time dependent simulation resulted in correct trends of the measured flame data. The reasonable behavior and high efficiency proves the usefulness of this method in difficult problems of flame propagation such as in internal combustion engines.

• Journal of the Korea Fashion and Costume Design Association
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• v.11 no.2
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• pp.33-42
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• 2009

The purpose of this study was to research the development of jacquard fabrics by the Bi-Dan patterns of Dan-Chung as one of the traditional korean symbols. For performing this design study, it designed a surface design of the geometric images in Bi-Dan patterns using by EAT Jacquard Textile CAD system and simulated to fabrics for the clothing & bags. To consider the modern image of Bi-Dan patterns in the Dan-Chung motives, the theoretical background was made on the basic elements, compositions and symbolic meanings of Dan-Chung patterns. To merchandise the fashion items and see the visual image, these jacquard fabric simulations was processed by two-dimension modeling through YoungWoo CNI CAD. The applied weave structure was based on a single layer of 5 or 10 points-satin and a double layer of 8 points-satin. Among the fabric simulations of Bi-Dan patterns, the six simulated fabrics were woven into the real jacquard fabrics under the electronic Stabuli jacquard loom in $120{\sim}130$ picks per inch and 171 ends per inch. These developed jacquard fabrics of Bi-Dan patterns were appeared a contemporary yet ethnic feeling so that they could make use of the unique korean cultural products by the further commercialization.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.33-43
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• 1998

High cutting speeds and feeds are essential requirements of a machine tool structure to accomplish its basic function which is to produce a workpiece of the required geometric form with an acceptable surface finish at as high a rate of production as is economically possible. Since the bearings in high speed spindle units are the main heat source of the total cutting system, in this work, the thermal characteristics of the spindle bearing system with a tilting axis were investigated using finite element methods to improve the performance of the spindle bearing system. Based on the theoretical results, a specially designed prototype spindle bearing system has been manufactured. Using the manufactured spindle bearing system, the thermal characteristics were measured. From the comparison of the experimental results with the theoretical ones, it was found that the finite element method predicted well the thermal characteristics of the spindle bearing system.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.37.2-37.2
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• 2013

Recently it turns out that simple-looking elliptical galaxies and lenticular galaxies are more complex and intriguing than expected. One of the most surprising and intriguing findings in extragalactic studies during the last two decades is a discovery that color distribution of the globular clusters in these galaxies is bimodal, suggesting that there are two subpopulations: blue and red globular clusters. We present a determination of the two-dimensional shape parameters of the blue and red globular cluster systems (GCSs) in a large number of bright elliptical galaxies and lenticular galaxies. The position angles of both and red GCSs show a correlation with those of the stellar light distribution, showing that the major axes of the GCSs are well aligned with those of their host galaxies. However, the shapes of the red GCSs show a tight correlation with the stellar light distribution as with the rotation property of their host galaxies, while the shapes of the blue GCSs do much less. These provide clear geometric evidence that the origins of the blue and red globular clusters are distinct and that these galaxies may have dual halos: a blue (metal-poor) halo and a red (metal-rich) halo. These two halos show significant differences in metallicity, structure, and kinematics, indicating that they are formed in two distinguishable ways. The red halos might have formed via dissipational processes with rotation, while the blue halos are through accretion.

• Composites Research
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• v.17 no.1
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• pp.38-46
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• 2004

This paper aims to correlate the micro-mechanical behaviour of tow geometry with applied in-plane forces during deformation of dry woven carbon-fibre fabric. These in-plane forces lead to differences in tow reorganisation during deformation and so changes in the way in which 'lock-up' occurs. In this paper, deformation of micro-mechanical parameters such as tow interval, crimp angle, change in tow amplitude and wavelength are investigated. To observe the micro-deformation of the fabric structure, appropriate specimens from bias extension and biaxial tests are sectioned and observed under the microscope. It was found that different loading conditions cause geometric deferences in the tow architecture. The variation in deformed tow geometry with shear angle is fitted using a simple parametric model.

• Journal of the Korea Furniture Society
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• v.26 no.1
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• pp.12-21
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• 2015

This is a study and work of furniture design adopted from a natural phenomenon, especially from the changing shapes of the moon. The drawer of furniture, a part frequently contacted with our hand (human body) is well related to the symbolism of the moon, which includes life conception and fertility. I created various forms of drawer handle shaped from the moon phases, which give a furniture design esthetical, symbolic and formative meanings. The characteristics of my drawer furniture designs are classified into 3 types. First, as the volumes of drawers increase, the handle shapes also change differently: old moon, crescent, half moon and full moon. Second, without keeping time order, drawers may have the same sizes with handles freely selected and arranged by formative accounts. Third, both increasingly changing type and freely selected and arranged type are combined to make a composite structure. In their simple geometric forms, these furnitures can provide nature intimacy, which fulfill the needs of our time.

• Journal of Fashion Business
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• v.14 no.1
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• pp.143-162
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• 2010

The purpose of this study is to suggest more specific method to express art connected to the factor of fashion design by classifying fashion case combined with contemporary art, which is expressed through visual factor of fashion, analyzing exchange phenomenon, trend and change aspect of art and fashion and researching its expression type under the background of art preference phenomenon of contemporary art. From the result of measuring the frequency of contemporary art type, it was found that various types and artists' works were applied to fashion industry. Therefore, the scope of contemporary art, which is used for fashion, is being enlarged and new type is appearing every year continuously. Especially, its frequency was highest in 2008 S/S. In addition, it was found that it was more frequent in S/S season rather than in F/W season. From the result of analyzing expression method of contemporary art inspiration shown in fashion by classifying it into structure aspect, print aspect and 3D decoration aspect, in most cases, the contemporary art was used as a print or pattern for dress or accessory. The print aspect could be divided into geometric abstraction pattern, expressional abstract pattern, trompe-l'oeil pattern, graffiti pattern, picture image pattern and cartoon pattern in detail.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.3
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• pp.219-228
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• 2001

The research into the field of managing urban utility information (such as gas pipes, power line, telecommunication utilities) is growing ever more important as the efficient management of social infra-structure gets higher and also with the fast technological progress made in nationwide scale of geo-spatial information systems. This research is focused on the collection of street utilities information in urban areas using aerial ortho-images. Until now this has been carried out by on site investigation and ground surveying methods. The result of this research shows that the geometric accuracy was obtainable within 12 cm referenced to 1/1,000 digital map. It was also possible to collect the street utilities which were described in the digital map as well as other information which were not.