• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.201-204
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• 1999

Polarization mode dispersion (PMD) restrict the bend-width of single mode optical filer, and it is important parameter in the optical fiber having long-length. Although fiber has perfect circular symmetry, fiber bending, twisting and laws governing manufacture cause additional Polarization mode dispersion. The effect of polarization mode dispersion in general single mode fiber of long length is discussed in this paper. Measurement of PMD with random mode coupling were conducted in two kind of fibers using different laws governing manufacture and interferometric method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.349-350
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• 2007

• Proceedings of the IEEK Conference
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.1273-1278
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• 2005

In this thesis, a 2 stage 6-pole bandpass filter(BPF) is designed and implemented by using triple-mode cavity for satellite payload system. The BPF has a 100MHz bandwidth at the center frequency of 14.5GHz(Ku-band) and the response of the filter is the Chebyshev function. The cavity filter uses two orthogonal $TE_{113}$ modes and one $TM_{012}$ mode. The coupling between the adjacent cavityes(intercavity coupling) results in a Chebyshev response and is accomplished by only H-filed component of TE modes. The size and location of intercavity slot is determined by the coupling equation from E- and H-field of TE and TM resonant modes in circular cavity. The 2-stage 6-pole triple-mode cavity BPF has the insertion loss of 2.4dB and the reflection loss of 15dB in the passband. The triple-mode BPF proposed in this thesis can be used as channel filters for satellite payload system and can minimize filter assembly in general wireless communication system.

• Journal of the Institute of Electronics Engineers of Korea TE
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• 제42권4호
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• pp.69-76
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• 2005

In this paper, a 2 stage 6-pole bandpass filter(BPF) is designed and implemented by using triple-mode cavity for satellite payload system. The BPF has a 100MHz bandwidth at the center frequency of 14.5GHz(Ku-band) and the response of the filter is the Chebyshev function. The cavity filter uses two orthogonal $TM_{113}$ modes and one $TM_{012}$ mode. The coupling between the adjacent cavityes(intercavity coupling) results in a Chebyshev response and is accomplished by only H-filed component of If modes. The size and location of intercavity slot is determined by the coupling equation from E-and H-field of TE and TM resonant modes in circular cavity. The 2-stage 6-pole triple-mode cavity BPF has the insertion loss of 2.4dB and the reflection loss of 15dB in the passband. The triple-mode BPF proposed in this thesis can be used as channel filters for satellite payload system and can minimize filter assembly in general wireless communication system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제27권1호
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• pp.1-7
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• 2016

In this paper, the tunable filter based on high power cavity using mechanical switch for 1.5 GHz band is presented. The LPF is inserted to eliminate the spurious wave, coupler is embeded to extract the output power, and then the tunable filter system is configured using mechanical switch. The LPF obtains attenuation over 40 dB between 4 GHz and 12.75 GHz, Coupler is satisfied with coupling value 40 dB and coupling isolation over 55 dB. The tunable filter system using mechanical switch obtains insertion loss 0.88 dB at bypass mode between 1,495.9 MHz and 1,510. 9 MHz, 3.29 dB at fil mode between 1,495.9 MHz and 1,500.9 MHz. It is also satisfied with output power of 132 W at the center frequency 1,498.4 MHz, and switching time below 10 ms.

• Journal of the Korean Institute of Telematics and Electronics D
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• 제34D권1호
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• pp.41-48
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• 1997

Design rules of directional coupler optical switches are discussed in consideration of parasitic couplings in the bending section. The parasitic coupling phenomenon is analyzed based on the coupled-mode theory and the solutions are represented in the form of the transfer matrix. The modified switching conditions due to the parasitic coupling are derived and the resultant switching diagrams are illustrated. It is revealed that the parallel section's length needs to be adjustd less than the coupling length $l_c(=\pi/2\textsc{k}o)$ to obtain the desired crosstalk and that the adjustment depends on the strength of the parasitic coupling. However, it is discovered that, for weak parasitic coupling, the switching voltage does not need to be altered but may maintain the same value as if no parasitic coupling is taken into account.

• Journal of electromagnetic engineering and science
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• 제18권1호
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• pp.46-51
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• 2018

In this paper, a planar printed hybrid short/open-ended slot antenna with capacitive coupling feed strips is proposed for hepta-band mobile applications. The proposed antenna is comprised of a slotted ground plane on the top plane and two capacitive coupling feed strips with a chip inductor on the bottom plane. At the low frequency band, the short-ended long slot fed by strip 1 generates its half-wavelength resonance mode, whereas the T-shaped open ended slot fed by strip 2 generates its quarter-wavelength resonance mode for the high frequency band. The antenna provides a wide bandwidth covering GSM850/GSM900/DCS/PCS/UMTS/LTE2300/LTE2500 operation bands. Moreover, the antenna occupies a small volume of $15mm{\times}50mm{\times}1mm$. The operating principle of the proposed antenna and the simulation/measurement results are presented and discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제18권8호
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• pp.1108-1116
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• 1993

Y-branch directional coupler optica1 switches with two different coupling lengths are fabricated on z-cut LiNbO3 and tested at r = 1.3 rm. The normal mode and coupled mode theories are utilized to calculate device coupling length and switching voltage. Simulation of the beam propagation method (BPM) is also performed to confirm the device coupling lengths. For dc operation, experimental results are in good agreement with the modee theories expectation.

• The Transactions of the Korean Institute of Electrical Engineers
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• 제36권7호
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• pp.447-452
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• 1987

In this paper, the dependence of piezoelectric properties in the 0-3 composite system of piezoelectric-ceramics polymer materials on particle size of ceramics were investigated. Radial mode and thickness mode of composite were observed similar to single phase of piezoelectric ceramics. The measured values of dielectric constant and dissipation factor were dependent on particle size, which increased with the increasing particle size. the planar coupling factor, thickness coupling factor and thickness frequency constant with the particle size were almost constant, while planar frequency constant increased. The thickness coupling factor decreased with the increasing thickness of specimen. It is found that maximum voltage coeffidient was calculated on the specimen with particle size smallar than 46 ${\mu}m$.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제18권5호
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• pp.564-571
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• 2008

This paper is concerned with the free vibration analysis of an annular plate with boundary conditions of simply supported-free, clamped-free and free-free, respectively. Exact solutions for the natural frequency and mode of an annular plate can be obtained by solving the differential equation but other methods such as the Rayleigh-Ritz method and the finite element method can be also used. In this research, we applied the Independent Coordinate Coupling Method(ICCM) to the annular plate and prove that the ICCM can accurately predict the natural frequency and mode shape of the annular plate. The numerical results show that the ICCM can be used effectively for the free vibration problem of plate with a hole compared to the Rayleigh-Ritz method and the finite element method.