• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.224-227
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• 2003

Single phase induction motor(SPIM) is one of the most widely used type of low power AC motors in the world, especially for domestic or commercial applications where a three phase power supply is not available. Fractional horse power of the SPIM have no starting torque their own. So there are several ways of starting SPIMS. The most common type is the starting capacitor installed in series with the auxiliary winding to increase the starting torque. Also, the auxiliary winding is disconnected once the speed of the motor reaches 70 to 80 [%] of the rated speed. In the conventional systems, this function is conducted by a centrifugal switch. But the mechanical centrifugal switch has many problems such as switch malfunction. This paper presents the starter design of SPIM capacitor starting switch using microcontroller.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.51-56
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• 2004

We propose and fabricate an 1${\times}$2 asymmetric optical switch by TOE using SOI wafer based on silicon which has very large TOE figure and it is a good material for optical devices. SOI wafer consists of 3 layers; upper Si layer for device(waveguide;core, n=3.5), buried oxide layer for insulator(clad, n=1.5) and Si substrate layer. We designed 1${\times}$2 asymmetric y-branched single mode optical waveguide switch by BPM simulation and metal heater by heat transfer simulation. Fabricated switch shows about 3.5 watts of power consumption and over 20dB of crosstalk between output channels.

• Journal of the Korea Society of Computer and Information
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• v.21 no.1
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• pp.65-72
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• 2016

Network virtualization is an emerging technology for solving the rigidity of the physical network infrastructure. The innovative technique virtualizes all resources in the network, including the network links and nodes, and provides a number of virtual networks on a single network infrastructure. In order to realize a virtual network, a thorough and complete monitoring of all resources in the network should be performed firstly. OpenFlow is an open source stack for network virtualization. However, it is impossible to apply OpenFlow to AP-based legacy wireless LAN environment because OpenFlow targets ethernet-based LAN environment. In this paper, we implement an adaptor-styled virtual switch for AP-based wireless LAN through customizing the Open vSwitch which is a virtual switch of OpenFlow. The evaluation test results show that the implemented OpenFlow stack operates successfully. The implemented OpenFlow stack can now be plugged immediately in existing AP-based wireless LAN environment and plays network resource monitoring. In the future, we can develop wireless LAN virtualization applications on the wireless OpenFlow stack.

• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.903-908
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• 2001

The gene aeg-46.5, which is expressed under anaerobic condition, has putative triple -10 regions and four transcription start sites. The mRNA transcription level and its start point change depending on the aerobic/anaerobic growth condition. RNA polymerase and its regulatory proteins must choose which of three -10 region to use. The putative triple 10 region was mutated to make only one of them function with consensus -10 region sequence (TATAAT) and the other two as non-functional region. The results show that the second and third -10 regions are used for the aerobic/anaerobic expression. The third -10 region is responsible for the high aerobic to anaerobic switch ratio. This suggests that only the last two of the putative triple -10 region have functions on aeg-46.5 gene expression switch control. The phenotype of the mutated promoter was tested in the wild type cell and narL - cell. The results indicate that the control by NarL is independent from the selection of -10 region. The expression patterns on multi-copy plasmids and on single-copy chromosome were compared. These results show that the aerobic/anaerobic switch control of aeg-46.5 is through the choice of -10 region. The mechanism of choosing different -10 region remains to be seen.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.327-332
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• 1999

In this paper, six harmonic injection PWM method for reducing total harmonic distortion in single switch three phase discontinuous conduction mode boost converter is presented. In the proposed method, periodic six harmonic voltage is injected in the control circuit to vary the duty ratio of the converter switch within a line cycle so that the fifth order harmonic of the input current is reduced. Experimental results are verified by converter operating at 400V/6kW with three phase 140V~220V input.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1110-1113
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• 2002

A Single-Stage Single-Switch power-factor- correction(PFC) AC/DC Converter with universal input is presented in this paper. The PFC Converter can be achieved based upon the continuous current mode(CCM). The switch has less current and voltage stresses over a wide range of load variation so that a low voltage rating device can be used. The presented converter features high power factor high efficiency, and low cost. An 90W prototype was implemented to show that it has 70% efficiency with low voltage stress over universal line input.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.82-90
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• 1999

A pulse frequency control method for single-switch three-phase buck rectifiers is comprehensively studied in this paper. The proposed pulse frequency control method leads the three-phase buck rectifier to a high performance system that can draw the nearly sinusoidal input-line currents. The simulated and experimental results demonstrate that the system provides low total harmonic distortion of the input-line currents, high-power factor, and good output voltage regulation against load change.

• Journal of Power Electronics
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• v.9 no.6
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• pp.929-939
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• 2009

This paper presents a new soft-switching boost converter based on the LC resonance and passive clamping technique without additional active switches. The circuit achieves high efficiency and low voltage stress by adopting a soft switching method using LC resonance. This paper gives a mathematical analysis of each mode and a detailed design procedure of the proposed boost converter. First of all, the operational principles are verified through simulation results. Then, according to the design procedure, we designed and built a 1.5[kW] prototype soft switching boost converter. Through the experimental results, we demonstrated the validity and usefulness of the proposed boost converter.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.173-175
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• 2009

A dc/dc converter for low voltage of battery application and fuel cell system is required to step up and regulate the low and widely variable voltage. In this paper, we have proposed a soft switching boost converter with high voltage gain using a single switch. Through the theoretical analysis and experimental result, operation modes and characteristics of the proposed topology is verified.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.1
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• pp.29-33
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• 2014

This paper proposes an alternate time-switched space-frequency block coding transmission technique for single-carrier modulation with frequency domain equalization. There are two antennas in the transmitter but it still has only a baseband and RF and a switch that alternates between the antennas at every symbol timing. Alternating transmit symbols result in zeros which make maximal ratio receive combining possible in the receiver. Simulation results show that it has better performance than the traditional algorithm at the expense of one additional antenna.