• Journal of the Korean Society of Industry Convergence
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• v.23 no.3
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• pp.499-505
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• 2020

Capacitor-run single-phase induction motor is cheaper than motors that use permanent magnets and is widely used in home appliances and industries based on relatively high durability and productivity. It can also be operated by line. However speed cannot be controlled because the line frequency is free. In this paper we dealt pole change method one of the method controlling speed of capacitor-run single-phase induction motor. The conventional pole change method is difficult to improve the power and efficiency of the motor because the composition of the pole change device is complex and do not have enough area of the windings because of windings not used according to the driving conditions. In this paper, we proposed the pole change method that is used main windings and auxiliary windings at 4 poles operation and used auxiliary windings as compensation windings at 2 poles operation. The proposed method was verified through finite element analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.229.1-229.1
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• 2014

Tactile sensors have widely been researched in the areas of electronics, robotic system and medical tools for extending to the form of bio inspired devices that generate feeling of touch mimicking those of humans. Recent efforts in adapting the tactile sensor have included the use of novel materials with both scalability and high sensitivity [1]. Graphene, a 2-D allotrope of carbon, is a prospective candidate for sensor technology, having strong mechanical properties [2] and flexibility, including recovery from mechanical stress. In addition, its truly 2-D nature allows the formation of continuous films that are intrinsically useful for realizing sensing functions. However, very few investigations have been carrier out to investigate sensing characteristics as a device form with the graphene subjected to strain/stress and pressure effects. In this study, we present a sensor of vertical forces based on single-layer graphene, with a working range that corresponds to the pressure of a gentle touch that can be perceived by humans. In spite of the low gauge factor that arises from the intrinsic electromechanical character of single-layer graphene, we achieve a resistance variation of about 30% in response to an applied vertical pressure of 5 kPa by introducing a pressure-amplifying structure in the sensor. In addition, we demonstrate a method to enhance the sensitivity of the sensor by applying resistive single-layer graphene.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.822-827
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• 2000

The Si-SiO$_2$interface trap and nitride bulk trap distribution of SONOSFET(polysilicon-oxide-nitride-oxide-semiconductor field effect transistor) NVSM (nonvolatile semiconductor memory) cell is investigated by single junction charge pumping method. The device was fabricated by 0.35㎛ standard logic fabrication process including the ONO stack dielectrics. The thickness of ONO dielectricis are 24$\AA$ for tunnel oxide, 74 $\AA$ for nitride and 25 $\AA$ for blocking oxide, respectively. By the use of single junction charge pumping method, the lateral profiles of both interface and memory traps can be calculated directly from experimental charge pumping results without complex numerical simulation. The interface traps were almost uniformly distributed over the whole channel region and its maximum value was 7.97$\times$10$\^$10/㎠. The memory traps were uniformly distributed in the nitride layer and its maximum value was 1.04$\times$10$\^$19/㎤. The degradation characteristics of SONOSFET with write/erase cycling also were investigated.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1480-1482
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• 2005

The major causes of power quality deterioration are harmonic current through semiconductor switching device, due to use of nonlinear loads such as diodes rectifier or thyristor rectifiers. In response to this concerns, this paper presents a new control method of single-phase active power filter(APF) for the compensation of harmonic current components in nonlinear loads. In order to make the complex calculation to be possible, the single-phase system that has two phases was made by constructing a imaginary second-phase giving time delay to load currents. In the conventional method, a imaginary-phase lagged to the load current T/4(here T is the fundamental cycle) was made. But in this proposed method, the new signal, which has the delayed phase through the filter, using the phase-delay property of low-pass filter, was used as the second phase. As this control method is applied to the system of single phase, an instantaneous calculation was done rather by using the rotating reference frames that synchronizes with source-frequency than by applying instantaneous reactive power theory that uses the conventional fixed reference frames.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.1
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• pp.42-46
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• 2006

This paper presents a method for deposition an individual carbon nanotube (CNT). The alignment of a single CNT is very useful to perform studies related to applications in FET (Field Emitted Transistor), SET (Single Electron Transistor) and to make chemical sensor as well as bio sensors. In this study, we developed the deposition method of a CNT individualized in a solution. Using the electrokinetic method, we found the optimum conditions to assemble the nanotube and discussed about plausible explanation for the assembling mechanism. These results will be available to use for making the CNT sensor device.

• Journal of Electrical Engineering and information Science
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• v.3 no.1
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• pp.110-116
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• 1998

A single-crystalline epitaxial film of GaAs has been grown on Si using a gs assisted-ionized vapour beam eptaxial technique. The native oxide layer on the silicon substrate was removed at 550$^{\circ}C$ by use of an accelerated arsenic ion beam, instead of a high-temperature desorption. During the growth the substrate temperature was maintained at 550$^{\circ}C$. Transmission electron microscopy and electron diffraction data suggest that the GaAs layer is an epitaxially grown single-crystalline layer. The possibility of growing device quality GaAs on Si is able demonstrated through fabrication of GaAs MODFET on Si substrates.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.171.1-171
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• 2001

This paper describes the design and implementation of a new type of a force reflective joystick. It has single degree of freedom that is actuated by motor and brake pair. The use of motor and brake allows various objects to be simulated without the stability problem and related safety issues involved with high torque motors only. The joystick performance is measured by its ability to simulate various test objects. Simple test objects are modeled as a benchmark test of the system´s performance and to evaluate different control approaches for hybrid motor/brake actuator. The force output joystick is capable of simulating forces in a variety of virtual environments. This device demonstrates the effectiveness of a hybrid motor/brake haptic actuator.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.1-4
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• 2014

Although physical modeling synthesis is becoming more and more efficient in rich and natural high-quality sound synthesis, its high computational complexity limits its use in portable devices. This constraint motivated research of single-instruction multiple-data many-core architectures that support the tremendous amount of computations by exploiting massive parallelism inherent in physical modeling synthesis. Since no general consensus has been reached which grain sizes of many-core processors and memories provide the most efficient operation for sound synthesis, design space exploration is conducted for seven processing element (PE) configurations. To find an optimal PE configuration, each PE configuration is evaluated in terms of execution time, area and energy efficiencies. Experimental results show that all PE configurations are satisfied with the system requirements to be implemented in portable devices.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.529-533
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• 2008

Mission Computer performs important role both managing a whole system and dealing with a specific mission in avionics system. In general, the fault of SPOF(Single Point Of Failure) in unity system can lead to failure of whole system. It can cause a failure of a mission and also can threaten to the life of the pilot. So, in this paper, we design the HA(High-availability) system so that dealing with the failure. And we use HA software like Heartbeat, Fake, DRBD and Bonding to managing HA system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.426-426
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• 2007

We report the field emission characteristics of transparent single-walled carbon nanotube (SWNT) film printed using an inkjet. Pure SWNTs dispersed in dimethylformamide were printed in a transparent layer on indium-tin oxide-coated glass and annealed at $350^{\circ}C$. After taping treatment, SWNTs were oriented vertically on the substrate. The front and the back of the fabricated device produced simultaneous emissions of identical quality. In addition, inkjet printing directly achieved a patterned emission, without a secondary pattern process. This method allows simple fabrication using only SWNTs, without the use of other additives.