• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.37-43
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• 2008

This paper introduces a high-speed low-power self-timed current-mode logic (STCML) that reduces both dynamic and leakage power dissipation. STCML significantly reduces the leakage portion of the power consumption using a pulse-mode control for shorting the virtual ground node. The proposed logic style also minimizes the dynamic portion of the power consumption due to short-circuit current by employing an enhanced self-timing buffer. Comparison results using a 80-nm CMOS technology show that STCML achieves 26 times reduction on leakage power consumption and 27% reduction on dynamic power consumption as compared to the conventional current-mode logic. They also indicate that up to 59% reduction on leakage power consumption compared to differential cascode voltage switch logic (DCVS).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.586-594
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• 2013

This paper proposes a new coupling element of microwave slot coupler for designing waveguide slot array which can reduce the effect of undesired higher order mode coupling between coupling and radiating slots in the branch waveguide. The proposed device is composed of a centered longitudinal shunt-series coupling slot at the center of broad wall shared by two crossed rectangular waveguides and an asymmetric compound iris that excites the coupling slot. We first have obtained scattering parameters for the proposed coupler by use of EM S/W tool HFSS and then extracted the parameters of T- network equivalent circuit for the coupling slot. We also have analyzed the resonant properties such as resonant length and normalized admittance by changing the geometrical dimensions. The measured results for the fabricated coupler with short-circuited block ${\lambda}_g/4$ away from the coupling slot are well agreed with the simulated ones.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.65-75
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• 1998

The $CO_2$ welding with 100% $CO_2$ gas is commonly used because of its cost and efficiency. Arc phenomena and spattering ratio of the $CO_2$ welding are influenced by various factors such as chemical compositions of welding wire, shielding gas, welding condition and welding power source etc.. Spattering ratio is predominantly influenced by the welding condition which determines a droplet transfer rode. In this study, arc phenomena and spattering ratio are investigated by using two type of FCW(titania type, semi-metal type). Then, the welding quality and optimum welding condition can be selected. From this study, the following results ware obtained; 1) In low current range(140A), FCW up to welding voltage(22V) resulted in a typical short circuit transfer, increase of spattering ratio and growth of spatter diameter. 2) In high current range(320A), the arc stability in titania FCW of a typical globular transfer is better than that of semi-metal FCW.

• Journal of Welding and Joining
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• v.25 no.6
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• pp.71-77
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• 2007

Until now, many researches on laser-arc hybrid welding processes have been conducted mainly for high power CW laser and high direct current arc to weld the thick steel plates for shipbuilding. Recently, however the usage of thin steel plates, which tend to be deformed easily by thermal energy, is been increasing because of demand of light structure such as car body in the automobile industry. Accordingly, heat sources having relatively low heat input such as pulsed laser, dip-transfer DC GMA and pulsed GMA seem to be applied more increasingly and the study about those heat sources is needed more intensively. Any heat source mentioned above can not stand alone without weld defects at a relatively high welding speed for increasing the welding productivity. This is main reason to apply the hybrid welding process which uses pulsed laser and low-heat-input GMA heat sources simultaneously to weld the thin steel plate. In this study, parameters of pulsed laser and dip-transfer DC GMA welding are studied firstly through preliminary experiments, and then analyzed in the viewpoint of their physical phenomena. Before conducting the hybrid welding, a pulse control technique is developed based on the parallel port communication and Visual C++ 6.0. Owing to development of this technique, interactions of laser and arc pulses can be controlled consistently. Using the pulse control technique, the hybrid welding is conducted and then its interactive welding phenomenon is analyzed.