• Journal of Power Electronics
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• v.3 no.3
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• pp.167-174
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• 2003

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with the rotor position, because the position of rotor is an essential information. Although high resolution optical encoders or resolvers are used to provide a precise position information, these sensors are expensive. Moreover, in the high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low cost analog encoder suitable for practical applications is proposed. And the control algorithm to generate switching signals using a Simple digital logic is presented. The validity of the proposed analog encoder with a proper logic controller is verified from the experiments.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.8
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• pp.390-396
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• 2002

This paper Presents to choose number of RGB LED through optical special quality analysis of RGB LED samples and to produce ratio of RGB LED for a stable color variation and white light. Also, it is to design of a simple switching circuit using some resistances and switching transistors that is able to operate each 16 RGB LED stably, and switching control circuit base on a microcontroller that would be suitable for colors variation patterns control more than about 64 patterns and colors variation more than about 100,000 colors using ON/OFF and Duty control.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.2
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• pp.131-137
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• 2003

We have performed computer simulation to obtain electro-optic chracteristics of reflective liquid crystal display (LCD) using wide viewing angle LC mode, fringe field switching(FFS). Unlike other reflective LCD modes, in the FFS mode, the LC director in plance so an application to reflective display consisted of polarizer, LC layer and reflector is possible. when an incident light is 550mm, the optimal cell retardation value is 0.1365${\mu}$m and the efficiency of reflectivity is high over 90% with very little wavelength dispersion. Further, we have studied a new reflective display with polarizer, optical compensation film with half plate, LC plus reflector. The display with optimized cell parameters shows high contrast ratio (CR) over 130 with high light efficiency over 90% at normal direction and the CR greater than 5 exists over 60$^{\circ}$ of polar angle in all directions.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.124-127
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• 2005

Rewritable optical memory devices such as an CD-RW and DVD+RW are data storage media, which take advantage of the different optical properties in the amorphous and crystalline states of phase change materials. The switching property, structural transformation, transformation kinetics and chemical bindings of $Ge_xSb_{100-x}$($6{\le}x{\le}$34) were studied to investigate the feasibility of applying $Ge_xSb_{100-x}$ alloys in optical memory. The $Ge_xSb_{100-x}$ thin film was deposited by RF magnetron co-sputtering system and phase change characteristics were investigated by X-ray diffraction (XRD), static tester, inductively coupled plasma atomic emission spectrometer (ICP-AES) and atomic force microscopy (AEM). Optimum fiim composition of $Ge_xSb_{100-x}$ was studied and its minimum time fur laser induced crystallization and optical contrast fur phase transition was performed. These results might be correlated with the binding energies between Ge and Sb, and indicate that $Ge_xSb_{100-x}$ have an potential far optical memory applications.

• ETRI Journal
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• v.31 no.6
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• pp.770-777
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• 2009

We have developed a fully functional reconfigurable optical add-drop multiplexer (ROADM) switch module using a polymer integrated photonic lightwave circuit technology. The polymer variable optical attenuator (VOA) array and digital optical switch array are integrated into one polymer PLC chip and packaged to form a 10-channel VOA integrated optical switch module. Four of these optical switch modules are used in the ROADM switch module to execute 40-channel switching and power equalization. As a wavelength division multiplexer (WDM) filter device, two C-band 40-channel athermal arrayed waveguide grating WDMs are used in the ROADM module. Optical power monitoring of each channel is carried out using a 5% tap PD. A controller and firmware having the functions of a 40-channel switch and VOA control, optical power monitoring, as well as TEC temperature control, and data communication interfaces are also developed in this study.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.171-177
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• 2009

Optical packet switching(OPS) is a strong candidate for the next-generation internet, since it has a fine switching granularity at the packet level for providing flexible bandwidth, and provides seamless integration between WDM layer and IP layer. Optical packet switching have been studied in two categories: OPS in synchronous and OPS in asynchronous networks. In this article we are focused on contention resolution of OPS in asynchronous networks. The hybrid buffer have been addressed, to reduce packet loss further as one of the alternative buffer structures for contention resolution of asynchronous and variable length packets, which consists of the FDL buffer and the electronic buffer. The OPS design issue for the limited number of TWCs and internal wavelengths is important in the aspect of switch cost and resource efficiency. Therefore, an hybrid buffer structured optical packet switch and its scheduling algorithm is presented for considering the limited number of TWCs and internal wavelengths, for contention resolution of asynchronous and variable length packets. The proposed algorithm could lead to the packet loss improvement compared to the legacy LAUC-VF algorithm with only the FDL buffer.

• Journal of Digital Contents Society
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• v.10 no.2
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• pp.199-207
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• 2009

The Q-switching the shutter or the different optical science element puts in within the laser light resonator and the storehouse departs from the within the resonator it loses the mortar and the reversal distribution which when is sufficient creates from within the active medium, opens the shutter instantaneously and it is to do to be made to emit with the light where the energy which is accumulated within the resonator is strong very. Like this Q-switching of laser resonator--It decreases factor increasing suddenly to make. To method of Laser Q-switching mechanical switching methods, electro-optic switching methods and switching by saturable absorber methods, acousto-optic switching method etc. 4 kind are being used on a large scale. In these people the conversion which is electric in compliance with the effect which is electrooptics is widely being used the Q-switching pulse of short pulse width because being it will be able to create. Consequently, Pockel cell where it has the quality of electrooptics effect) the Q-it is become known that it is suitable it uses with switch. From the research which it sees FET and one-chip microprocessor where it is a switching element and pulse transfomer to plan and produce pockel cell Q-switch driving gears, pulse style Nd: It applied in YAG Laser system and it investigated and researched the operating characteristic of the Q-switch. Also, the Q-switch leads and Nd where it is output: YAG with forecast in compliance with a theoretical calculation it comes to buy laser beam side politics it compared and laser beam qualities which had become Q-switching it analyzed.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.136-138
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• 2004

IP망을 활용한 VPN(Virtual Private Network)에서의 QoS 보장 및 광대역 서비스 제공에 대한 해결 방안으로 차세대 광 인터넷을 통한 OVPN(Optical VPN) 기술이 제시되고 있다. 차세대 광 인터넷의 구현이 IP/GMPLS(Generalized Multi-Protocol Label Switching) over DWDM(Dense Wavelength Division Multiplexing) 프로토콜 프레임워크로 표준화되고 있는 현실에 비추어 볼 때 IP/GMPLS over DWDM 백본망을 통한 OVPN은 차세대 가상사설망으로써 멀티미디어 서비스 제공을 위한 최적의 방안이다. 이러한 멀티미디어 서비스 제공을 위한 OVPN에서는 최적의 Optical-LSP(Label Switched Path)의 설립이 요구되고 있다. 따라서 본 논문에서는 차세대 OVPN의 모델 및 망의 blocking probability를 향상하기 위한 미래의 잠재적인 연결 요구에 대해 간섭을 최소화하면서 경로를 설정하는 MW-MIPR 라우팅 알고리즘을 제시하고 이를 라우팅 프로토콜인 OSPF-TE+(OSPF Extensions in Support of Generalized MPLS)에 맵핑하기 위한 방안을 제안한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1829-1834
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• 2008

An optical switch/modulator is designed and the light propagating characteristics is analyzed by the simplified BPM. The distinctive feature of the switch/modulator is that all the waveguide branches are designed to be single-mode. Principle of the device is based on the coupled mode theory in the Y-junction interconnecting waveguide. In spite of all the waveguides are designed to be single-mode, adjusting the interconnecting waveguide length of the device, the same characteristics as existing device up to date is obtainable. Numerical results show that the switching characteristics periodically depends on the interconnecting waveguide length with a spatial of about 150${\mu}m$ in the Ti:LiNbO3 step index waveguide. The concept of design would be utilized effectively in fabricating the monolithic high density of optical integrated circuit.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.26-27
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• 2004

We present the first demonstration of the vertical-injection depleted optical thyristor laster diode with InGaAs/InGaAsP multiple quantum well structure. The measured switching voltage and current are 3.36 V and 10 A respectively. The holding voltage and current are respectively 1.37 V, 100 A. The lasing threshold current is 131 mA at 25 C. The output peak wavelength is at 1578 nm at a bias current equal to 1.22 times threshold.