• Journal of Welding and Joining
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• v.16 no.6
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• pp.59-68
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• 1998

In this study, effects of solidification modes (primary $\delta$-ferrite, primary ${\gamma}$-austenite) on the pit initiation and propagation in the 304L and 316L austenitic stainless steel weld metals were investigated. The solidification mode of weld metal was controlled by the addition of nitrogen to Ar shielding gas. Through the electrochemical experiments (potentiodynamic anodic polarization and potentiostatic time-current transient test) and metallographic examination (microstructure and elemental distribution), the following results were obtained. The more the volume content of nitrogen in the shielding gas were, the lower critical current density for passivity was observed. In comparison with weldments solidified through the primary $\delta$-ferrite solidification mode and the primary ${\gamma}$-solidification mode, the former showed higher critical pitting potential and a longer incubation time for stable pit initiation than the latter. However, in the pit propagation stage the former exhibited a faster dissolution rate than the latter. These results were believed to ee related to the distribution of alloying elements such as Cr, Mo, Ni and S.

• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.45-50
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• 1995

The excellent c-axis oriented zinc oxide thin films were prepared by the RF magnetron sputtering method on glass substrates. Optimum fabrication conditions of the ZnO films were such that RF power, substrate temperature, and gas pressure of mixture Ar(50%):$O_{2}$(50%) were 150 W, $200^{\circ}C$, and 5 mTorr, respectively. In these conditions, the deposition rate was $310\;{\AA}/min$, and the resistivity of the film was $1{\times}10^6\;{\Omega}{\cdot}cm$. The ZnO film also showed high c-axis orientation and crystalinity according to XRD pattern and SEM photograph. A fabricated interdigital transducer generated 1st mode surface acoustic wave at 46.6 MHz and 2nd mode surface acoustic wave at 52.5 MHz. At the 1st mode, the phase velocity of surface acoustic wave and the electromechanical coupling coefficient were 2795 m/sec and 0.031 %, respectivly. At the 2nd mode, they were 3149 m/sec and 0.019 %. respectivly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2093-2099
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• 2016

This paper describes a design of crypto-processor that supports multiple block cipher algorithms of PRESENT, ARIA, and AES. The crypto-processor integrates three cores that are PRmo (PRESENT with mode of operation), AR_AS (ARIA_AES), and AES-16b. The PRmo core implementing 64-bit block cipher PRESENT supports key length 80-bit and 128-bit, and four modes of operation including ECB, CBC, OFB, and CTR. The AR_AS core supporting key length 128-bit and 256-bit integrates two 128-bit block ciphers ARIA and AES into a single data-path by utilizing resource sharing technique. The AES-16b core supporting key length 128-bit implements AES with a reduced data-path of 16-bit for minimizing hardware. Each crypto-core contains its own on-the-fly key scheduler, and consecutive blocks of plaintext/ciphertext can be processed without reloading key. The crypto-processor was verified by FPGA implementation. The crypto-processor implemented with a $0.18{\mu}m$ CMOS cell library occupies 54,500 gate equivalents (GEs), and it can operate with 55 MHz clock frequency.

• Journal of the Korean Ceramic Society
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• v.45 no.9
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• pp.524-530
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• 2008

Anti-Reflective (AR) thin film coatings of $SiO_2$ (n= 1.48) and $TiO_2$ (n=2.17) were deposited by ion-beam assisted deposition (IBAD) with End-Hall ion source and conventional electron beam (e-beam) evaporation to investigate the effect of deposition method on the refractive indicies (n) of the fIlms. Green-light generation using a GaAs laser diode was achieved via excitation of the second harmonic. The latter resulted from the transmission of the fundamental guided-mode wave of 1064 nm through periodically poled $LiNbO_3$. Large differences in the refractive indicies of each of the layers in the multilayer coating may improve AR performance. IBAD of $SiO_2$ reduced its refractive index from 1.45 to 1.34 at 1064 nm. Conversely, e-beam evaporation of $TiO_2$ increased its refractive index from 1.80 to 2.11. In addition, no fluctuations in absorption at the wavelength of 1064 nm were found. The results suggest that films prepared by different deposition methods can increase the effectiveness of multilayer AR coatings.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6C
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• pp.561-570
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• 2009

Ultra-wideband communication systems based on impulse radio have merits that are possible for the high data rate transmission, high resolution ranging are positioning system. Conventionally, in order to accomplish these features, the high-speed ADC (Analog to Digital Convertor) is necessary to apply radio determination system operating in time domain. However, considering low rate - wireless personal area network (LR-WPAN) aims to low-cost hardware implementation, the expensive ADC converting GHz sampling per second is not appropriate. So, this paper introduces a low complex AR (Auto Regressive) model based non-coherent ranging scheme operating in frequency domain with using low-speed ADC utilizing analog Voltage Control Oscillator (VCO) mode for the frequency domain transformation. To verify the superiority of the proposed ranging and location algorithm working in frequency domain, the suggested IEEE 802.15.4a TG channel model is used to exploit affirmative features of the proposed algorithm with conducting the simulation results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.6
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• pp.34-41
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• 1984

MOEN/MO double layer which is to be used It)r the RMOS (refractory metal oxide semiconductor) gate material has been fabricated by means of low temperature reactive sputtering in N2 and Ar mixture. Good Mo2N film was obtained in the volumetric mixture of Ar:N2=95:5. The sheet resistance of the fabricated Mo7N film was about 1.20 - 1.28 ohms/square, which is about an order of magnitude lower than that of polysilicon film, and this would enable to improve the operational speed of devices fabricated with this material. When PSG (phosphorus silicate glass) was used as impurity diffusion source for the source and drain of the RMOSFET in the N2 atmosphere at about 110$0^{\circ}C$, the Mo2N was reduced to Mo resulting in much smaller sheet resistance of about 0.38 ohm/square. The threshold voltage of the RMOSFET fabricated in our experiment was - 1.5 V, and both depletion and enhancement mode RMOSFETs could be obtained.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.2
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• pp.106-113
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• 2009

Recently, due to many industrial accidents at construction sites, a variety of researches for structural health monitoring (SHM) of buildings are progressing. For real site application of SHM, one of the advanced technologies has blown as wireless sensor networks (WSN). In this paper, we proposed WIVA(WSN Monitoring framework based on 3D Visualization and Augmented Reality in Mobile Devices) system that applies 3D visualization and AR technology to mobile devices with camera based on WSN in order to expand the extent of information can observe. Moreover, we performed experiments to validate effectiveness in 3D and AR mode that utilize WSN data based on IEEE 802.15.4. In real implementation scenario, we demonstrated a fire occurrence test in 3-story building miniature.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.135-140
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• 2015

Decomposition of carbon dioxide is studied using $Ar/CO_2$ mixture inductively coupled plasmas (ICP). Argon gas was added to generate plasma which has high electron density. To measure decomposition rate of $CO_2$, optical emission actinometry is used. Changing input power, pressure and mixture ratio, the plasma parameters and the spectrum intensity were measured using single Langmuir probe and spectroscope. The source characteristic of Carbon dioxide ICP observed from the obtained plasma parameters. The decomposition rate is evolved depending on the reaction and discharge mode. This result is analyzed with both the measurement of the plasma parameters and the dissociation mechanism of $CO_2$.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.463-468
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• 2021

In this paper, when a refractive index grating and a gain grating were simultaneously present in a DFB laser having a wavelength of 1.55 ㎛, a dielectric film coating was applied so that reflection did not occur on the right mirror surface, so that 𝜌_r=0. In case of 𝛿L>0, the characteristics of the oscillation frequency and oscillation gain were analyzed. When the grating phase of the left mirror surface continues to decrease from 𝜋, the graph lines of each mode gradually shift to the left. In case of 𝜅L=10, the threshold gain of the oscillation mode is the lowest. In this case, the mode selectivity is relatively low. From 𝜅L=0.5 to 𝜅L=6, the mode selectivity and the frequency stability are excellent. In the case of DFB lasers with an anti-reflection coated mirror, the threshold gain of the oscillation mode increases but the mode selectivity is about twice as excellent, compared with DFB lasers of having two cleaved facets.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.486-491
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• 2001

The effect of S content in welding wires on spattering characteristics and droplet transfer phenomena was studied. In MAG welding using 80%Ar-$20%CO_2$ shielding gas, spattering characteristics and droplet transfer phenomena were varied with S content of wire. Sulfur addition in wire reduced surface tension of droplet and weld pool, and made arc more stable in MAG welding. With increasing S content, the spattering ratio and the ratio of large size spatter ($d{\geq}1.0mm$) were reduced in short circuit transfer mode. In spray transfer mode, spattering ratio, however was increased when sulfur was added more than 0.020wt.% because surface tension of droplets and weld pool was reduced too much even though arc stability was improved.