• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.2
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• pp.112-116
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• 2018

Electric double layer capacitors (EDLCs) are promising candidates for energy storage devices in electronic applications. An EDLC yields high power density but has low specific capacitance. Carbon material is used in EDLCs owing to its large specific surface area, large pore volume, and good mechanical stability. Consequently, the use of carbon materials for EDLC electrodes has attracted considerable research interest. In this paper, in order to evaluate the electrochemical performance, graphene is used as an EDLC electrode with flake sizes of 3, 12, and 60 nm. The surface characteristic and electrochemical properties of graphene were investigated using SEM, BET, and cyclic voltammetry. The specific capacitance of the graphene based EDLC was measured in a 1 M $TEABF_4/ACN$ electrolyte at the scan rates of 2, 10, and 50 mV/s. The 3 nm graphene electrode had the highest specific capacitance (68.9 F/g) compared to other samples. This result was attributed to graphene's large surface area and meso-pore volume. Therefore, large surface area and meso-pore volume effectively enhances the specific capacitance of EDLCs.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.133-136
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• 2002

It is very important to get a stable and large-capacity organic effusion source for achievement of OLED mass-production equipment. We present an organic effusion source with film uniformity less than ${\pm}$ 5%, the material charge volume, 300cc for $400{\times}400\;mm^2$ substrate. The fine metal shadow mask alignment technology, one of the color forming technique, also have to support more accurate and fast operating in mass-production. In this paper, we will describe the OLED mass-production equipment with the large volume effusion source and the precision shadow mask alignment technique.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.187-190
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• 2002

To study adiabatic shear band formation of tungsten heavy alloys, 5 prismatic specimens are loaded by high velocity impacts and treated as plane strain problems. Their volume percent of tungsten particles in WHA are 81%, 93% and 97% respectively and for the fixed 81% volume percent, small size particle model, large size particle model, undulated particle models are considered and then, the effects of particle's volume ratio, geometry and size to the formation of shear band are discussed.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.11-18
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• 1997

Scientific volume visualization addresses the representation, manipulation, and rendering of volumetric data sets, providing mechanisms for looking closely into structures and understanding their complexity and dynamics. In the past several years, a tremendous amount of research and development has been directed toward algorithms and data modeling methods for a scientific data visualization. But there has been very little work on developing a mathematical volume model that feeds this visualization. Especially, in flow visualization, the volume model has long been required as a guidance to display the very large amounts of data resulting from numerical simulations. In this paper, we focus on the mathematical representation of volumetric data sets and the method of extracting meaningful information from the derived volume model. For this purpose, a B-spline volume is extended to a high dimensional trivariate model which is called as a flow visualization model in this paper. Two three-dimensional examples are presented to demonstrate the capabilities of this model.

• Ocean and Polar Research
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• v.34 no.4
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• pp.403-411
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• 2012

Among others, a question that has long been unanswered is why the seasonal variation of volume transport is larger in the Soya and Korea/Tsushima Straits than in the Tsugaru Strait. An attempt is made to answer this question in terms of the island rule with friction being taken into account. The problem is idealized as a simple model. The model results indicate that volume transport through a channel is determined not only by the circulation created around the adjacent island but also by those created around the neighboring islands farther away. The latter is due to the presence of bottom friction in the channels. The volume transports through the Korea/Tsushima, Tsugaru and Soya Straits estimated from the model using observed wind data show the general pattern of observed seasonality, although they contain large errors associated with the uncertain frictional parameter employed in the model. The model indicates that the observed seasonality arises essentially from the fact that wind stress curl changes its sign, from negative in the summer to positive in winter, following a large fluctuation of zero-stress curl latitude east of Hokkaido.

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.81-88
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• 1996

In order to investigate the electrical properties of transformer oils for large power, the characteristics of AC and Impulse breakdown in gap length of 1.0~2.5mm and that of volume resistivity were researched in temperature range of 20~$100^{\circ}C$. An geometrical capacitance of electrode with coaxial cylindrical shape for measuring the volume resistivity was 16pF, and highmegohm meter with model no. VMG-1000 was used, and also the applied voltage were DC 100, 250 and 500V. In the dependance of breakdown characteristics due to electrode gap length, it was confirmed that breakdown voltage was nearly uniform by volume effect according to the increase of gap. In the characteristics for AC breakdown, the dielectric strength was increased to $90^{\circ}C$ but decreased over $90^{\circ}C$, and also in case of impulse breakdown, it was increased to 7$0^{\circ}C$ and at dated $70^{\circ}C$ over in temperature range. The calculated mobility of oils in the characteristics for impulse breakdown were about $10^{-5}$~$10^{-4}cm^2/V{\cdot}S$, and the value of volume resistivity was almost invariable in low temperature range, regardless of voltage by the stable thermal properties, and it indicated a peak at $50^{\circ}C$ and had a sudden change to decrease over that temperature, and also the value of volume resistivity in 250V/mm at $80^{\circ}C$ is suitable for the International electrical standards, it was confirmed.

• International Journal of Highway Engineering
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• v.18 no.1
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• pp.109-117
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• 2016

PURPOSES : The goal of this study is to analyze the operational effects of special roundabouts at large-scale rotaries in Korea. In pursuing the above, this study gives particular attention to comparing standard roundabouts with special roundabouts. METHODS : This study reviews the various types of roundabouts, creates 270 scenarios, builds networks, and comparatively analyzes the operational effects by using VISSIM simulation model and SSAM(Surrogate Safety Assessment Model). RESULTS : First, the operational effects of standard and signalized roundabouts were analyzed, and it was determined that standard roundabouts are the best in the case of under-saturated traffic volume, and signalized roundabouts are the best in the case of over-saturated traffic volume. Second, the operational benefits of a Turbo roundabout were evaluated to be generally lower than the benefits of a standard roundabout, and the benefits of a Turbo roundabout increase when right-turn traffic volume increases. Finally, the safety conflicts of a Turbo roundabout were determined to be the least and decrease when right-turn traffic volume increases. CONCLUSIONS : This study suggests that Turbo roundabouts rank highest for safety, and signalized roundabouts are best for over-saturated traffic volume. This study can be expected to provide some implications for policy decision-making.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.169-172
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• 2000

Direct volume rendering has yet been restricted to high-end graphic workstations and special-purpose hardware, due to the large amount of trilinear interpolation, that are necessary to obtain high image quality. In this paper, we implemented the volume rendering techniques using the 2D-texture at the environment of standard PC hardware. In addition, we show how multi-texturing capabilities of modern PC graphics board are enable to volume rendering. Besides using extended OpenGL function, we improved pixel operations and rendering capacity.

• Journal of Korea Multimedia Society
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• v.22 no.7
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• pp.759-769
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• 2019

Since a surgery simulation should be able to represent the internal structure of the human body, it is advantageous to adopt volume based techniques rather than polygon based techniques. However, the volume based techniques induce large computation to deform heterogeneous volume datasets such as bones and muscles. In this study, we propose a new method to deform volume data using multi-core CPUs. By improving previous studies, the proposed method minimizes unnecessary propagation operations. Moreover, we propose an efficient task-partitioning method for volume deformation using multi-core CPUs. As a result, we can simulate the deformation of heterogeneous volume data at an interactive speed without special hardware.

• Journal of The Korean Astronomical Society
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• v.44 no.6
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• pp.217-234
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• 2011

We present two large cosmological N-body simulations, called Horizon Run 2 (HR2) and Horizon Run 3 (HR3), made using $6000^3$ = 216 billions and $7210^3$ = 374 billion particles, spanning a volume of $(7.200\;h^{-1}Gpc)^3$ and $(10.815\;h^{-1}Gpc)^3$, respectively. These simulations improve on our previous Horizon Run 1 (HR1) up to a factor of 4.4 in volume, and range from 2600 to over 8800 times the volume of the Millennium Run. In addition, they achieve a considerably finer mass resolution, down to $1.25{\times}10^{11}h^{-1}M_{\odot}$, allowing to resolve galaxy-size halos with mean particle separations of $1.2h^{-1}$Mpc and $1.5h^{-1}$Mpc, respectively. We have measured the power spectrum, correlation function, mass function and basic halo properties with percent level accuracy, and verified that they correctly reproduce the CDM theoretical expectations, in excellent agreement with linear perturbation theory. Our unprecedentedly large-volume N-body simulations can be used for a variety of studies in cosmology and astrophysics, ranging from large-scale structure topology, baryon acoustic oscillations, dark energy and the characterization of the expansion history of the Universe, till galaxy formation science - in connection with the new SDSS-III. To this end, we made a total of 35 all-sky mock surveys along the past light cone out to z = 0.7 (8 from the HR2 and 27 from the HR3), to simulate the BOSS geometry. The simulations and mock surveys are already publicly available at http://astro.kias.re.kr/Horizon-Run23/.