• Transactions on Electrical and Electronic Materials
• /
• v.14 no.5
• /
• pp.246-249
• /
• 2013

Graphene was obtained on Cu foil by thermal decomposition method. A gas mixture of $H_2$ and $CH_4$ and an ambient annealing temperature of $1,000^{\circ}C$ were used during the deposition for 30 Min., and for the transfer onto $SiO_2/Si$ and Si substrates. The physical properties of graphene were investigated with regard to the effect ofnitrogen atom doping and the various substrates used. The G/2D ratio decreased when the graphene became monolayer graphene. The graphene grown on $SiO_2/Si$ substrate showed a low intensity of the G/2D ratio, because the polarity of the $SiO_2$ layer improved the quality of graphene. The intensity of the G/2D ratio of graphene doped with nitrogen atoms increased with the doping time. The quality of graphene depended on the concentration of the nitrogen doping and chemical properties of substrates. High-quality monolayer graphene was obtained with a low G/2D ratio. The increase in the intensity of the G/2D ratios corresponded to a blue shift in the 2D peaks.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.37 no.6
• /
• pp.662-667
• /
• 2024

In this study, the electrical properties of a C0G (class 1 ceramic) dielectric composition with internal reducibility, specifically (Ba_0.27CaSr)(Zr_0.95Ti_0.05)O₃, were investigated by fixing Ba at the A site and varying the Ca/Sr molar ratio. The potential application of this composition in high-permittivity C0G MLCCs was examined. The powder was calcined at 1,150℃ for 2 hours, as determined by TG-DTA analysis, and the resulting powder was ground to achieve a particle size (D50) of 0.35 to 0.4 ㎛ and a specific surface area (BET) of 4.5 to 5.0 g/m². With a Ca/Sr molar ratio of 0.3, the composition (Ba_0.27Ca_0.17Sr_0.56) (Zr_0.95Ti_0.05)O₃ exhibited electrical properties with a permittivity of 41.9, a loss of less than 0.008%, and an insulation resistance exceeding 2.2×10¹³ Ω. The feasibility of using this composition for high-capacitance C0G MLCCs was confirmed.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2005.11a
• /
• pp.125-130
• /
• 2005

This paper suggests an efficient method of protection ratio calculation and shows some calculated results applicable to frequency coordination in microwave relay system networks, and the net filter discrimination (NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively, In addition, NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

• Fashion & Textile Research Journal
• /
• v.1 no.4
• /
• pp.387-392
• /
• 1999

The effects of the ratio of warp diameter to filling diameter (${\beta}$-ratio) and warp thread crash on the crimp factor and the yarn curvature were studied theoretically in this paper. The models of 2/2 twill fabric derived square cloth and sinusoidal curved cloth were used for the theoretical analysis. The crimp factors (C) for the models were given theoretically as follows; (1) Derived square cloth(general equation for b) $$C=\frac{(1+{\beta})({\theta}-sin{\theta})}{(1+{\beta})sin{\theta}+{\alpha}}$$ (2) Sihusoidal curved cloth $$C=\frac{(1+{\beta})sin{\theta}\[1+\{\frac{{\pi}(1-cos{\theta})}{4sin{\theta}}\}^2\]+{\alpha}}{(1+{\beta})sin{\theta}+{\alpha}}-1$$ The curvatures(${\kappa}$) for the models were given theoretically as follows; (1) Derived square cloth $${\kappa}=\frac{2}{d_w+d_f}$$ (2) Sinusoidal curved cloth $${\kappa}=\|{^{\;\;\prime\prime} \atop r}(s)\| \\ where \;s=\frac{p^'}{{\pi}}\(u+\frac{k^2u}{4}+\frac{k^2}{8}sin2u\)$$.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.24 no.3
• /
• pp.129-133
• /
• 1998

We have studied a relationship between the pattern of complex modulus change versus internal phase volume ratio and the rheological consistency of concentrated W/O emulsions with Magnesium Sulfate in the range 0.0 to 0.5 wt% and with different oil polarities, respectively. The rheological consistency with time of concentrated W/O emulsion was checked using Fudoh Rheometer and the coalescence of deformed water droplets was examined using polarized light microscope(LEICA DMRP). To find the pattern of complex modulus change of the concentrated emulsions versus internal phase volume ratio, the effect of varying water phase volume fraction from 0.78 up to 0.85 on viscoelastic measurements was investigated using rotational rheometer (HAAKE Rheostress RS 50). The rheological consistency was mainly destroyed by the coalescence of the deformed water droplets. The greater the increase of complex modulus was, the less coalescence occurred and the more consistent the concentrated emulsions were. And the pattern of complex modulus increase versus volume ratio has been explained with the resistance to coalescence of the deformed interfacial film of water droplets in concentrated W/O emulsion.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.1 s.343
• /
• pp.133-142
• /
• 2006

This paper suggests an efficient method of protection ratio(PR) calculation and shows some results of point-to-point radio relay system for frequency coordination. The proposed PR can be expressed as a function of C/N of modulation scheme, noise-to-interference ratio(N/I), multiple interference allowance, fade margins of multi-Path and rain attenuation and net filter discrimination. And PR calculation is performed in view of fade margin, modulation scheme, distance, and interference for actual point-to-point radio relay frequency. According to results for 6.2 GHz, 64-QAM and 60 km at BER 10-6, fade margin and co-channel Protection ratio reveal 41.1dB and 74.9 dB, respectively The merit of presented method provides a systematic and easy calculation by means of PR correction factor related with various parameters and can apply the same concept to frequency coordination of millimeter wave radio relay system.

• Membrane and Water Treatment
• /
• v.8 no.2
• /
• pp.171-184
• /
• 2017

This study presents the effect of hydraulic retention time (HRT) on the characteristics of emission of three major greenhouse gases (GHGs) including $CH_4$, $CO_2$ and $N_2O$ during operation of a sequencing batch reactor for aerobic oxidation of methane with denitrification (AeOM-D SBR). Dissolved $N_2O$ concentration increased, leveled-off and slightly decreased as the HRT increased from 0.25 to 1d. Concentration of the dissolved $N_2O$ was higher at the shorter HRT, which was highly associated with the lowered C/N ratio. A longer HRT resulted in a higher C/N ratio with a sufficient carbon source produced by methanotrophs via methane oxidation, which provided a favorable condition for reducing $N_2O$ formation. With a less formation of the dissolved $N_2O$, $N_2O$ emission rate was lower at a longer HRT condition due to the lower C/N ratio. Opposite to the $N_2O$ emission, emission rates of $CH_4$ and $CO_2$ were higher at a longer HRT. Longer HRT resulted in the greater total GHGs emission as $CO_2$ equivalent which was doubled when the HRT increased from 0.5d to 1.0 d. Contribution of $CH_4$ onto the total GHGs emission was most dominant accounting for 98 - 99% compared to that of $N_2O$ (< 2%).

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1049-1052
• /
• 2004

In general, contrary to the CRTs with impulsive emission, liquid crystal displays have motion artifacts such as blurring. ghost image, decrease of dynamic CR(contrast ratio), and stroboscopic motion due to hold type driving method. In this paper, to improve motion picture quality of LCDs. impulsive driving method of black data insertion was applied to the OCB mode which is well known for its fast LC response time and wide viewing angle properties. Subject evaluation was carried out with CRT, TN, SIPS(Super IPS). and impulsive driving OCB. Moving picture image quality near CRT was obtained in impulsive OCB driving mode

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.18 no.1
• /
• pp.26-32
• /
• 1996

This study was performed to determine the ideal mixing ratio of toothash and plaster of Paris. The histopathologic and histomorphometric study of bone response of five implant materials, toothash(Group A), tooth and plaster mixture, mixing ratio due to weight 2 : 1(Group B), 3 : 1(Group C), 4 : 1(Group D), and plaster Paris(Group E), were performed in rat calvarial defect. No sign of extensive inflammatory reaction was defected. Newly-formed bony ingrowth occurred in all experimental groups except for group E at 12 weeks after operation. Bone was deposited directly on the surface of implant materials. The highest rate of direct bony union between implant material and newly-formed bone occurred with the group B, followed group C, D, and A.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.4
• /
• pp.117-123
• /
• 2016

A hand-gesture interface to manipulate a 3D object of augmented reality is implemented by recognizing the user hand-gesture in this paper. Proposed method extracts the hand region from real image, and creates augmented object by hand marker recognized user hand-gesture. Also, 3D object manipulation corresponding to user hand-gesture is performed by analyzing a hand region ratio, a numbet of finger and a variation ratio of hand region center. In order to evaluate the performance of the our proposed method, after making a 3D object by using the OpenGL library, all processing tasks are implemented by using the Intel OpenCV library and C++ language. As a result, the proposed method showed the average 90% recognition ratio by the user command-modes successfully.