• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.43-49
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• 2004

In this paper, we have designed a mode size converter to reduce coupling loss between super-high delta silica optical waveguides and single mode fibers. The new mode size converter has three design aspects; periodically segmented taper waveguide for minimal size, lateral taper waveguide for simple fabrication, and surrounding trenches to improve coupling loss. In the optimal mode size converter design, coupling loss is 0.33dB/point without trenches and 0.2dB/point with trenches.

• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.340-346
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• 2000

Traveling wave type semiconductor optical amplifiers integrated with spot-size-converter (SSC-TW-SOA) have been extensively studied for the improvement of coupling effiClency With single-mode fiber and fO! the cost reducClon 111 a packaging In tlIis paper the slructural dependence of the spot-slZe-converter on the effective facet reflectlvllY $R_{eff}$ was experimentally as well as thcoretienlly mvestlgated. It was shown that not only a sufficient mode-conversion in a sse region along the latersl and tran~verse directions but also an introductIOn of angled-facet were very essential in order to reduce $R_{eff}$ Very small ripple less than 0.1 dB in an amplified spontaneous emission spectrum was observed with the fabncated SSC-lW-SOA which consists of the wrndow length of $20\mu\textrm{m}$, facet angle of $7^{\circ}$, and antlrelleetioll-coated facet of ] % reflectivity.tivity.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.170-172
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• 2007

본 논문은 optocoupler를 사용하여 궤환단을 절연한 오프라인 플라이백 변환기의 설계와 해석에 중점적인 목적을 두었으며, 부가적으로 궤환단을 절연하지 않은 구조를 가지는 전류모드제어 플라이백변환기와 optocoupler로 궤환단을 절연한 구조를 가지는 전류모드제어 플라이백 변환기의 상관관계를 분석하였다. 설계와 해석을 하기 위해 PSIM 시뮬레이터를 사용하여 PSIM 모델을 제시하였으며, 제시한 PSIM 모델은 110$\sim$220V 오프라인 전원을 입력하여 10V/5A의 출력을 가지는 50W 오프라인 전류모드 플라이백 변환기의 설계와 실험을 통하여 높은 정확성과 사용의 용이성을 확인하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.347-351
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• 2010

판과 같은 구조물의 손상 감지를 위해, 손상 전 구조물의 임피던스 신호를 기저신호(Baseline impedance signal)로 이용하여 직접적으로 비교하지 않는 새로운 개념의 무기저 손상진단 기법(Reference-free impedance method)을 제시한다. 박막 압전소자(이하 PZT)를 판의 상하 표면에 부착시킨 한 쌍의 병치 PZT를 이용하여 손상으로 인해 모드변환을 일으키는 전기역학적 신호(Electro Mechanical Signatures ; 이하 EMS)를 추출한다. 이 연구에서는 스펙트럼 요소법(Spectral Element Method ; 이하 SEM)을 이용하여 주파수 영역에서 병치된 PZT의 EMS를 파악하기 위한 수치해석을 수행한다. 특히, 손상에 의해 발생된 모드변환 EMSMC를 병치된 PZT의 극성에 기인한 신호분해 기법을 적용하여 추출하고, 분해된 모드변환 EMSMC가 손상의 위치와 크기에 따라 받는 영향을 추가로 분석한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.41-46
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• 2023

Design of W-band TE10 to TEM mode converter for radial power combiner is proposed in this paper. The proposed structure is used with generally available pin to realize TEM mode and is designed to convert TE10 to TEM mode gradually using 2-step impedance transformer and back short. The pin of proposed mode converter is well bonded to the housing so that environment conditions such as vibration or shock are not affected. The proposed mode converter, in a back-to-back configuration, has less than 1.55 dB insertion loss and more than 10 dB return loss from 92.5 GHz to 97.7 GHz. Proposed converter is expected compact radar and various applications requiring for high power and stable environment conditions.

• Korean Journal of Optics and Photonics
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• v.29 no.3
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• pp.104-109
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• 2018

We explain the basic principle of transformation optics, and introduce several design techniques for transformation cavities that can maintain the characteristics of whispering gallery modes (WGMs) even if the cavity is strongly deformed from a circular shape. As a method of obtaining various transformation cavities under a specific conformal mapping, we suggest a method of parallel movement of the initial cavity domain, and a method of rotating the ellipse as a cavity domain. The internal wave pattern and the far-field output characteristics of several designed resonant modes are numerically calculated. From these results, it is confirmed that a variety of GRIN resonators are possible for a given conformal coordinate transformation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1123-1130
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• 2004

In this paper, a technique is presented f3r the design of a structurally simple narrow-band orthomode transducer (OMT) operating at 12/14 GHz frequency bands. The proposed OMT has such a structure that a horizontally polarized wave incident on the circular waveguide of the common port is directed to the rectangular waveguide of the straight port, while the vertically polarized wave is directed to the rectangular waveguide of the side port. Firstly methods are developed f3r designing individual parts of the OMT based on the waveguide theory and the theory of impedance matching. Secondly based on developed methods the whole OMT structure is designed using a commercial electromagnetic field analysis software. The validity of the proposed design technique is confirmed by fabricating and testing the designed OMT.

• Journal of IKEEE
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• v.15 no.4
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• pp.299-304
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• 2011

In this paper, the circular polarized horn antenna composed of circular polarizer and impedance transformer is designed, and fabricated. For the circular polarizer, two types of the polarizer are designed and the electrical performance of them is compared; rectangular waveguide polarizer with $45^{\circ}$-inclined dielectric slab and oval shaped one. Straight type mode converter has a stepped impedance structure and plays a role of converting waveguide TE mode into coaxial TEM mode, and the proposed antenna is designed to directly connect with active components using the feed-through in the input port of the mode converter. Fabricated antenna has the wideband performance, VSWR<1.5 and Axial ratio < 1.0dB, ranging from 30.085 to 30.885 GHz, and the antenna gain is 6.7~7.0 dBi.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.22-27
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• 2004

In this paper, we designed a mode size converter to reduce coupling loss between optical waveguide and single mode fiber. The proposed mode converter is composed of periodically segmented tapered waveguide to achieve small size and easy fabrication. For the optimally designed mode size converter at 1550nm, the taper length is 500(equation omitted), the segmentation period 5ß:, the waveguide width of fiber contact section 1.3ß:, and duty cycle 0.95. The coupling loss of the optimized mode size converter is 0.33㏈/point, which is 1.27㏈/point lower than that without the mode size converter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1180-1186
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• 2008

The LNB phase noise of user terminal for high data rate satellite transmission was analyzed in this paper. The phase noise severely affects the service performance in low data rate transmission as well as multi-mode signal for high data rate. As the satellite link frequency is increased, the effects of phase noise for multi-mode signal is increased. The phase noise of LNB, which is operated in high frequency band, is about equal to the transmission system phase noise and have an major effects on service performance degradation. The available transmission mode was analyzed in presence of phase noise of LNB and analysis method for LNB phase noise spectrum distribution was proposed in multi-mode signal.