• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.443-447
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• 2003

In this work. using 0.2 GaAs modulation doped FET(MODFET), a high performance DBS downconverter MMIC was developed for direct broadcasting satellite (DBS) application. Without LNA, the downconverter MMIC showed a very low noise of 4.8 dB, which is lower by 3 dB than conventional ones. A low LO power of -10 dBm was required for the normal DBS operation of the downconverter MMIC. which reduced the power consumption via a removal of LO amplifier on MMIC. It required only a low power consumption of 175 mW, which is lower than 70 percent of conventional ones. The LO leakage power at IF output was suppressed to a lower level than 30 dBm, which removes a bulky LO rejection filter on a board. The fabricated chip, which include a mixer, If amplifiers. LO rejection filter, and active balun, exhibited a small size of $0.84{\times}0.9\textrm{mm}^2$.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.1-11
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• 2000

This study is aimed to develop a proto-type LPG engine for medium-duty commercial vehicles in order to substitute for conventional diesel engine. Recently, it is recognized that diesel engines are main cause for smoke pollution in urban site. So, it is expected to reduce this environmental emission by developing and substituting LPG engine which has the advantage of practical use in a short development period in aspects of infrastructures. For that, after analysing the specifications and performance characteristics of a base diesel engine, parts of combustion chamber, intake system, fuel supply and ignition systems suitable for LPG combustion were re-designed and manufactured. And and engine controller for fuel supply and ignition distributions was matched by feedback mapping based on the speed-load conditions. The torque and power of LPG engine were increased by 6∼12% on the overall driving conditions compared to the base diesel engine, and fuel consumption rate marked the similar level based on the fuel price. Exhaust emissions such as THC, CO, NOx recorded the same order with conventional LPG engine for passenger car.