• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.2
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• pp.128-136
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• 2001

This paper evaluates the performance of an optic link in a frequency conversion based fiber-radio system. The proposed link structure simplifies a BS(base station) via making the MMW(millimeter wave) optical pilot tone generated in the CS(control station) be used in the uplink as well as in the downlink. To acquire the optical pilot tone, an EOM(electro-optic modulator) in the CS is biased in three different ways, i.e., MAB(maximum bias), MIB(minimum bias), QB(quadrature bias). We, depending on the biasing of the EOM, evaluate the link performances in two cases; one is for constant laser source power and the other for constant received DC optical power at a PD(photo detector). Based on the simulation results on the downlink CNR and the uplink SFDR(spurious free dynamic range), we finally deduce the effective EOM biasing for each case.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.3-11
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• 2005

For monitoring of the civil and building structure, optical fiber sensors are very convenient. The fiber sensors are very small and do not disturb the structural properties. They also have several merits such as electro-magnetic immunity, long signal transmission, good accuracy and multiplexibility in one sensor line. Strain measurement technologies with fiber optic sensors have been investigated as a part of smart structure. In this paper, we investigated the possibilities of fiber optic sensor application to the monitoring of beam-column joints of structures. We expect that the fiber optic sensors replace electrical strain gauges. The commercial electric strain gauges show good stability and dominate the strain measurement market. However, they lack durability and long term stability for continuous monitoring of the structures. In order to apply the strain gauges, we only have to attach them to the surfaces of the structures. In this paper, we investigate the possibility of using fiber optic Bragg grating sensors to joint structure. The sensors show nice response to the structural behavior of the joint.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.595-601
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• 2003

For monitoring of the civil and building structure, optical fiber sensors are very convenient. The fiber sensors are very small and do not disturb the structural properties. They also have several merits such as electro-magnetic immunity, long signal transmission, good accuracy and multiplicity of one sensor line. Strain measurement technologies with fiber optic sensors have been investigated as a part of smart structure. In this paper, we investigated the possibilities of fiber optic sensor application to the monitoring of beam-column joints of structures. We expect that the fiber optic sensors replace electrical strain gauges. The commercial electric strain gauges show good stability und dominate tile strain measurement market. However, they lack durability and long term stability for continuous monitoring of the structures. In order to apply the strain gauges, we only have to attach them to the surfaces of the structures. In this paper, we investigate the possibility of using fiber optic Bragg grating sensors to joint structure. The sensors show nice response to the structural behavior of the joint.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.5
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• pp.442-451
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• 1992

Mach-Zehnder type GaAs elcetro-optic waveguide modulator has been designed in this paper.The modulator. Considered is based on the Mach-Zehnder interferometer configuration, consisting of two Y branch couping rib type waveguides formed in two epitaxial layers on GaAs substrate. The mode theory on waveguides and electo-optic effect of GaAs were utilized to determine the design parameters for the modulator proposed. Effective index method was applied to design the of waveguide supporting a single mode were calculated to achieve the optimized operation of the modulator. Considering interrelationships between many parameters.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.2
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• pp.195-199
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• 2006

We report a novel simulation method to calculate optical transmission considering the real paths of optic introduced in a unit pixel of TFT-LCDs using three-dimensional molecular director simulation of the tensor model. The simulation of optical path transmission profile was carried out by calculating new permittivity considered the real paths of optic in liquid crystal cell. As a result, it was clarified that the electro-optic characteristics such as movement of disclination line, contrast ratio and transmittance profile show a large difference according to the viewing angle compared with the conventional method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.81-86
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• 2006

We have studied electrode-optic characteristics of in-plane switching (IPS) of liquid crystal director driven by an oblique electric field. Because the conventional IPS mode does not have an electrode on top substrate, it shows not only slow response time due to weak electric field but also slow discharging problem when electrostatic field is generated after fabricating the cell. To solve these problems, we have formed additional electrode including dielectric layer in the inner part of the cell on top substrate and studied electrode-optic characteristics of the new device.

• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.416-423
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• 2000

A new demodulation technique which can be used for the fiber optic acoustic sensor system using Sagnac interferometer is described. The theoretical limitation in dynamic range of the quadrature demodulation technique can be removed by the proposed BPSK(Binary Phase Shift Keying) demodulation technique. Full demodulation of input acoustic signal is possible with just simple electronics by eliminating the necessity of the high frequency phase modulation. This technique is suitable for digital signal processing of fiber optic sensor systems and can be applicable for other interferometers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1111-1117
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• 1999

In order to measure the temperature of bridge wire, the explosive material is removed from EED and a fiber optic temperature sensor is installed near the bridge wire. Using the heat transfer theory, the optimum position of the fiber optic sensor in the EED is determined and the temperature-distance equation is derived from test result. The measuring technique can be utilized to the real electromagnetic radiation hazard test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.104-108
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• 2005

We have studied electrode-optic characteristics of IPS (in-plane switching) mode with electrode on top substrate. Because the IPS mode does not have electrode on top substrate. it shows not only slow response time due to weak electric field but also slow discharging problem when electrostatic field is generated after fabricating the cell. To solve these problems. we have formed additional electrode including dielectric layer in the inner part of the cell and studied electrode-optic characteristics of new IPS cell by changing thickness of dielectric layer.

• Korean Journal of Optics and Photonics
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• v.12 no.5
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• pp.414-417
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• 2001

Experimentally, the aligned direction of AFLCs in electro-optic cells having both the substrates rubbed along the same direction is skewed by a few degrees from the rebbing direction. To explain why, we proposed "Torsional Rigid Body Model" and interpreted their skewing angle as the action of short pitch with the large shear stress. That is, the azimuthal an anchoring strength (about 35 dyn/cm) in the cell is much larger than the maximum shear stress (about 10$^{-6}$ dyn/cm) for the original pitch and so forbids the optic axis to skew. On the side hand, the strength is smaller than the maximum shear stress (about 42 dyn/cm) for short pitch and then allows the optic axis to skew.