• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.10
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• pp.41-50
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• 1993

This paper describes the fabrication process and electrical characteristics of PSA (Polysilicon Self-Align) bipolar transistors with a thin base width of 1100.angs.. To realize this shallow junction depth, one-step rapid thermal annealing(RTA) technology has been applied instead of conventional furnace annealing process. It has been shown that the series resistances and parasitic capacitances are significantly reduced in the device with emitter area of 1${\times}4{\mu}m^{2}$. The switching speed of 2.4ns/gate was obtained by measuring the minimum propagation delay time in the I$^{2}$L ring oscillator with 31 stages.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.7
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• pp.462-469
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• 1987

A metal gate MOSFET with source/drain regions self-aligned to gate region is proposed. The proposed MOS transistor is fabricated by utilizing the higher oxidation rate of source/drain regions with high doping concentration when compared with channel region with moderate doping. The thick oxide on the source/drain regions reduces the gate and drain(source) overlap capacitance down to that of a self-aligned polysilicon gate device while allowing the use of a metal gate with much lower resistivity than the more commonly used polycrystalline silicon. A ring oscillator composed of 15 inverter stages has been computer simulated using SPICE. The results of the simulation show good agreement with experimental measurement confirming the fast switching speed of propesed MOSFET.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.206-209
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• 2002

With the progress of semiconductor processing technology, avalanohe photodiodes (APDs) based on InP/InGaAs are used for high-speed optical receiver modules. Planar-type APDs give higher reliability than mesa-type APDs. However, Planar-type APDs are struggled with a problem of intensed electric field at the junction curvature, which causes edge breakdown phenomena at the junction periphery. In this paper, we focused on studying the effects of junction curvature for APDs performances by different etching processes followed by single diffusion to from p-n junction. The performance of each process is characterized by observing electric field profiles and carrier generation rates. From the results, it can be understood to predict the optimum structure, which can minimize edge breakdown and improve the manufacturability.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.435-436
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• 2008

This paper presents a dual band frequency synthesizer for GSM and Wideband CDMA which is designed in a standard 0.13um CMOS 1P6M process. The shared components include phase frequency detector (PFD), charge pump (CP), loop filter, integer frequency divider(128/129 DMP, 4bit PC, 3bit SC) and Low noise Ring-VCO. A high-speed low power dual modulus prescaler is proposed to operate up to 2.1GHz at 3.3V supply voltage with 2mW power consumption by simulation. The simulated phase noise of VCO is -101dBc/Hz at 200kHz offset frequency from 1.9GHz.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.353-356
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• 1999

A 3.3V PLL(Phase Locked loop) is designed for a high frequency, low voltage, and low power applications. This paper proposes a new PLL architecture to improve voltage to frequency linearity of VCO(Voltage controlled oscillator) with new delay cell. The proposed VCO operates at a wide frequency range of 30MHz~1㎓ with a good linearity. The DC-DC voltage up/down converter is utilized to regulate the control voltage of the two-stage VCO. The designed PLL architecture is implemented on a 0.6${\mu}{\textrm}{m}$ n-well CMOS process. The simulation results show a locking time of 2.6$\mu$sec at 1Hz, Lock in range of 100MHz~1㎓, and a power dissipation of 112㎽.

• Journal of Aerospace System Engineering
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• v.1 no.1
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• pp.36-44
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• 2007

This study was performed on preliminary structural design of a small scale WIG craft which has been developed as a next generation high speed maritime transportation system in Korea. A composite structure design using the foam-sandwich for main wing and tail fins and the honeycomb sandwich and skin-stringer-ring frame for fuselage was applied for weight reduction as well as structural stability. A commercial FEM code, NASTRAN for was utilized to confirm the structural safety for the reiterate design modifications to meet design requirements including the target weight. Each main wing was jointed with the fuselage by eight high strength insert bolts for easy assembling and disassembling as well as for assuring the required 20 years service life. For control surface structural design, the channel type spar, the foam sandwich skin and the lug joint were adopted.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.225-231
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• 1997

This paper reports on the theoretical study of the delivery pressure ripples of a positive displacement vane pump which is widely used for automobile power steering. Pressure ripples occur due to the flow tipples which induced cam ring profiles and reverse flow from the delivery ports. In this paper, the mathematical model for analyzing the pressure ripples has been presented, and set of the differential equationshave been solved using the Runge-Kutta method. As the results of analysis, instant ideal flow ripples, internal pressure, delivery pressure ripples, and delivery flow ripples have been presented. Internal pressure was related to delivery pressure variations, and amplitude of pressure tipples was increased with rotational speed and delivery pressure.

• Journal of Industrial Technology
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• v.19
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• pp.179-187
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• 1999

The computer pattern sewing machine is an automatic sewing machine that is controlled by an input pattern. Even a novice can run this machine for various tasks fast and reliably such as sewing a button, a belt ring and an airbag, etc. The pattern processing software, which is the main software of this machine, is for editing and modifying pattern data by online teaching or off-line editing, setting up parameters, and calculate a moving distance of working area on the x-y axes. In this paper we propose an algorithm to generate pattern data for sewing by simplifying image data. The pattern data are composed of outline data like dot, line, circle, arc, curve, etc. We need converting this data into sewing data which involve sewing parameter, moving distance of working are an the x-y axes, thread, spindle speed.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.1
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• pp.64-72
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• 2009

In order to convert efficiently vibration energy of a car tire wheel into electrical power by using piezoelectric materials, the design of the materials must be performed for the dynamic characteristics of the piezoelectric materials to be matched with them of the vibration energy sources well. An accelerometer was installed on the tire wheel with a slip ring to investigate the dynamic mode of the wheel as one of the vibration energy sources. During road test, the measurement on the vibration mode of the tire wheel was performed with variations of car speed and road condition. The experimental data were analyzed details for availability as a micro power source for wireless TPMS(Tire Pressure Monitoring System).

• 전기의세계
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• v.22 no.3
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• pp.25-34
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• 1973

In this paper, the characteristics of a single phase induction motor which is considered the space harmonic flux by the double revolving field theory is analysed. As the rotor resistance for the fundamental flux is separated from the resistance for the rotor bar and end-ring, and the rotor leakage reactnace is separated from the skew leakage reactance and the other, so the circuit constants for the space harmonic flux is expressed by the circuit constants for the fundamentals. As the ratio of the circuit constants for the magnetizing reactance is used, the generalized equivalent circuit is made up. the characteristic equation which is able to analysis the subdivided characteristics by the above circuit is induced. The ratio of the circuit constants and the skew angle being changed, the variations of the torque-speed characteristics for the fundamentals and harmonics is examined by this equation.