• ETRI Journal
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• v.37 no.1
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• pp.97-106
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• 2015

In this paper, MOS-triggered silicon-controlled rectifier (SCR)-based electrostatic discharge (ESD) protection circuits for mobile application in 3.3 V I/O and SCR-based ESD protection circuits with floating N+/P+ diffusion regions for inverter and light-emitting diode driver applications in 20 V power clamps were designed. The breakdown voltage is induced by a grounded-gate NMOS (ggNMOS) in the MOS-triggered SCR-based ESD protection circuit for 3.3 V I/O. This lowers the breakdown voltage of the SCR by providing a trigger current to the P-well of the SCR. However, the operation resistance is increased compared to SCR, because additional diffusion regions increase the overall resistance of the protection circuit. To overcome this problem, the number of ggNMOS fingers was increased. The ESD protection circuit for the power clamp application at 20 V had a breakdown voltage of 23 V; the product of a high holding voltage by the N+/P+ floating diffusion region. The trigger voltage was improved by the partial insertion of a P-body to narrow the gap between the trigger and holding voltages. The ESD protection circuits for low- and high-voltage applications were designed using $0.18{\mu}m$ Bipolar-CMOS-DMOS technology, with $100{\mu}m$ width. Electrical characteristics and robustness are analyzed by a transmission line pulse measurement and an ESD pulse generator (ESS-6008).

• Computers and Concrete
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• v.21 no.2
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• pp.117-126
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• 2018

This research investigate the behavior of reinforced normal and lightweight aggregate concrete hollow core slabs with different core shapes, shear span to effective depth (a/d). The experimental work includes testing seven reinforced concrete slabs under two vertical line loads. The dimensions of slab specimens were (1.1 m) length, (0.6 m) width and (0.12 m) thickness. The maximum reduction in weight due to aggregate type was (19.28%) and due to cross section (square and circular) cores was (17.37 and 13.64%) respectively. The test results showed that the decrease of shear span to effective depth ratio from 2.9 to 1.9 for lightweight aggregate solid slab cause an increase in ultimate load by (29.06%) and increase in the deflection value at ultimate load or the ultimate deflection by (17.79%). The use of lightweight aggregate concrete in casting solid slabs give a reduction in weight by (19.28%) and in the first cracking and ultimate loads by (16.37%) and (5%) respectively for constant (a/d=2.9).The use of lightweight aggregate concrete in casting hollow circular core slabs with constant (a/d=2.9) (reduction in weight 32.92%) decrease the cracking and ultimate loads by (12%) and (5.18%) respectively with respect to the solid slab. These slab specimens were analyzed numerically by using the finite element computer program ANSYS. Good agreements in terms of behavior, cracking load (load at first visible crack) and ultimate load (maximum value of testing load) was obtained between finite element analysis and experimental test results.

• ETRI Journal
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• v.39 no.4
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• pp.535-545
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• 2017

This paper presents a novel K-band (18 GHz) 16-quadrature amplitude modulation (16-QAM) orthogonal frequency-division multiplexing (OFDM)-based $2{\times}2$ line-of-sight multi-input multi-output communication system. The system can deliver 356 Mbps on a 56 MHz channel. Alignment mismatches, such as amplitude and/or phase mismatches, between the transmitter and receiver antennas were examined through hardware experiments. Hardware experimental results revealed that amplitude mismatch is related to antenna size, antenna beam width, and link distance. The proposed system employs an alignment mismatch compensation method. The open-loop architecture of the proposed compensation method is simple and enables facile construction of communication systems. In a digital modem, 16-QAM OFDM with a 512-point fast Fourier transform and (255, 239) Reed-Solomon forward error correction codecs is used. Experimental results show that a bit error rate of $10^{-5}$ is achieved at a signal-to-noise ratio of approximately 18.0 dB.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.233-233
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• 2015

We report on a simple method for inducing physical and chemical property-gradient on nanoimprinted patterns by intensity-regulated plasma treatment under caved sample stage. As for the size gradient, a line pattern having a linewidth of 294.9 nm was etched to have gradually varying width from 277.4 nm to 147.9 nm. Modified pattern was proven to be adaptable to replica stamp for reversal patterning. To investigate the wettability gradient, imprinted nanopatterns were coated with fluoroalkylsilane to increase the hydrophobicity, and the surface was modified to have gradually varying wettability from hydrophobic to hydrophilic (contact angle was ${\sim}160^{\circ}$ to ${\sim}5^{\circ}$ on a single chip). This method is expected to be applicable to the selective adsorption of biological entities and hydrodynamic manipulation of liquid droplets for the pumpless microfluidics.

• Ceramist
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• v.10 no.3
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• pp.67-74
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• 2007

Crystallisation kinetics of the erbium doped soda-tellurite glasses were studied using the differential thermal analysis (DTA) and differential scanning calorimetery (DSC) techniques. The DTA curves in the temperature range of 350 K to 650 K were obtained from isochronal heating rates, chosen in the range of 2 to 20 K/min. DSC isothermal curves were used to calculate the fraction of crystals formed on reheating. The apparent activation energies for devitrification were derived by measuring the shifts in the values of $T_g$ and $T_x$ with heating rates, using the Kissinger method. The derived values of apparent activation energies for isochronal and isothermal methods varied in the range of $190-204\;{\pm}\;5\;kJ\;mol^{-1}$. The X-ray powder diffraction analysis of heat treated and transparent samples showed the presence of nano-scale size sodium-tellurite crystals. These crystallites were found to have a strong influence on the full width of half maxima of the transition in $Er^{3+}:\;^4I_{13/2}{\rightarrow}^4I_{15/2}$, which extended from 70 nm in the vitreous materials to 132 nm in glass-ceramic materials.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1051-1061
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• 1995

In order perform leak-before-break design of nuclear piping systems and integrity evaluation of reactor vessels, full stress-strain (.sigma. - .epsilon.) curves and fracture resistance (J-R) curves are required. However it is time-consuming and expensive to obtain J-R curves experimentally. The objective of this paper is to develop two methods for J-R curve prediction. In the first method, elastic-plastic finite element analyses for a series of crack length / specimen width ratio were performed. Accordingly the load versus load line displacement (P .delta.) curve corresponding to the fracture strain is obtained and the J-R curve based on the generalized locus method is obtained. In the second method, the correlation between .sigma.-.epsilon. curves and J-R curves was statistically analyzed and an empirical equation to predict the J-R curve from the .sigma.-.epsilon. test result is proposed. A good correlation between the predicted results based on the proposed methods and the experimental ones is obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.401-401
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• 2009

Recently, demands for the development of compact, lightweight power supplies with higher power density and higher efficiency have been increased. Since Piezoelectric Transformer (PT) was emerged in device and material industry, it has been suggested as a viable alternative to the magnetic transformer in some applications. PT has some advantages such as low profile and mechanical energy transfer with little electromagnetic interface (EMI). Also, PT can provide high voltage stepping ratio with good isolation and requires no copper windings saving copper usage especially for large voltage conversion differences. Conventional control of PT converter has mainly two-way. One is the pulse frequency modulation (PFM) control method and the other is the pulse width modulation (PWM) control with frequency fixed method. It is known that the maximum PT efficiency can be obtained when it operates near the resonant frequency of the PT. And, also PT's resonant frequency moves according to the load condition. Therefore, selection of PT converter control method is very difficult. This paper analyzes general piezo-electric converter modeling and proposes a guide-line to selection of control method and stabilization control.

• Bulletin of the Society of Naval Architects of Korea
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• v.21 no.1
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• pp.43-47
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• 1984

The purpose of this paper is to investigate theoretically the effect of residual stress due to welding in stress intensity factor of a plate containing the Model I Crack in different crack size and location, and on fatigue crack growth rate. The initiation of crack is found to be possible only in the region of tensile residual stress. The most dangerous crack has the values of d/b and a/b equal to about 0.6 and 1.0, respectively, where d/b is the ratio of distance from the crack to welding bead and the width of tensile residual stress region and a/b is the ratio of crack length and tensile residual stress region. The crack perpendicular to and on the line of welding bead and with a/b equal to about 0.6 has maximum stress intensity factor. The theoretical fatigue crack growth rate under residual stress and applied stress, which is obtained from Forman's Law by stress superposition, is relatively in good agreement with Glinka's[8] experimental value. The fatigue crack growth is shown to be retarded due to residual stress distribution.

• Journal of Korean Society of Transportation
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• v.5 no.2
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• pp.81-95
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• 1987

In line with the continued growth of car ownership, the traffic problems in central area of metropoles such as Seoul would become increasingly degraded. comparing with most western cities, the problems in Seoul are characterized by the improportionately high rates of intersection delay, station congestion, traffic accidents caused by weaving conflicts and pedestrian congestion. It is caused by the lack of flexibility I street network, which is prerequisite for upholding the efficacy of traffic management and control, resulted from the simplicity of network graph in terms of connectivity, street density and distribution by width. This pattern has been resulted from the prolonged policy pursuing the street-widening of the nagging bottleneck in such a short period since the 1950s, comparing that most western cities had undergone over several centuries an age of horse-and-vehicle transportation. In order to improve the expected traffic problems in central area over the coming periods of motorization, it is imperative to restructure the street network in Central Seoul so that the efficacy of traffic management and control may be operative. Based upon the long-range planning the street network should be restructured by stages so that cenral traffic may be controled by one-way operation and most through-traffic be detoured around fringe area.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.4 s.346
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• pp.44-51
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• 2006

In this paper, the resonance characteristics of zigzag wire dipole antennas are first analyzed by the method of moment(MOM) for shortening the space occupation length of straight wire dipole antenna Considering the shortening effect the integrated zigzag dipole antennas with the simplified microstrip feed are designed. Since the integration gives rise to discontinuities due to antenna line width with abrupt bend angles, the compensation by the chamfer is applied. Futhermore the integrated parasitic zigzag lines are properly attached to both sides of substrate for compensation of the effect of the dielectric substrate, hence improving the resonance characteristic. The design results at UHF and ISM band are verified with experiments.