• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.6
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• pp.287-295
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• 1985

Analysis and design procedures for the symmetrical and non-symmetrical interdigitated four-port microstrip couplers conssiting of symmetrical three lines is presented. The configuration is simple and a lesser number of bond wires are requires as compared to the four-line couplers which are used. Physical dimensions of 3. 6 and 10dB couplers with substrates having typical dielectric constant values of 2.55 and 10 can be found by using the tables and charts.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.5
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• pp.603-613
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• 1998

Resonant characteristic of Whispering modes(W. G. mode) on a dielectric disk resonator is influenced by an external circuit that is placed near the disk to excite this type of modes. In order to evaluate this phenomenon, we divide the disk resonator as two parts; a coupling part in which the mode coupling occurs and on uncoupled region. In the coupled part, we regard the part of the disk as a curved waveguide which is loaded with matched circuit, and derive a coupled mode equation for nonparallel dielectric waveguides. From the coupled mode equation, we calculate coupling coefficients and a coupled electromagnetic field. By using the complex coupling coefficients, we can calculate power transfer. We also calculate a resonant frequency in consideration of the mode coupling phenomenon. The calculated resonance frequence is confirmed by experiment for the resonance characteristics. As the results, it is found that the discrepancy between the theoretical and the experimental resonance frequencies is about 1.28% and the discrepancy between theory and experiment of FSR is about 0.6%.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.231-238
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• 2019

In this paper, we have studied how to improve the amplifiers efficiency by minimizing the combining loss when several unit power amplifiers are combined to obtain high output power. Specifically, we have developed Ka-band Spatial Combining Amplifier. The fabricated Spatial Combining Amplifier is a Ka-band 20W class SSPA, which uses a 5W class unit amplifier module 8EA designed using a GaN bare die. We also combined The unit amplifier module using 8-way spatial divider and combiner with a hybrid radial structure. The output combining loss of the fabricated spatial coupler is about 0.334dB, which is about 92.6% efficiency. In this paper, we developed a Spatial Combining Amplifier with a maximum saturation output of 10W and a power addition efficiency of over 15%. As a result, we achieved the maximum saturation output of 30W and the power addition efficiency of 19%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.320-327
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• 2005

In this paper, compensation structures are proposed in the CPW directional couplers with finite-extent backed conductor for tight coupling. The proposed structures are realized T-shaped expanded slots and modified finite-extent backed conductor in CPW coupled structure. The T-shaped expanded slots was used to avoide reduced coupling and modified finite extent backed conductor of dumbbell shape was used to enhance directivity and matching. The designed CPW directional couplers at 1 GHz has good directivity without reducing coupling in simulation by EM solver based on full-wave analysis and measurements.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.11-19
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• 2010

In this paper, H-plane filtering-horn antenna operating at millimeter frequency band is proposed with embedded filter and three-layered dielectric lens for frequency selection and maintenance of main beam direction, respectively. The waveguide-typed filter and H-plane sectoral horn antenna are replaced with considerably size-reduced PCB substrate-typed filtering antenna using via fences and several posts. The waveguide-typed filter and H-plane sectoral horn antenna were designed in air-filled waveguide and then combined into size-reduced PCB substrate. For the control of the thickness of dielectric lens, single and multi dielectric lens have been employed. As a result of antenna gain, 8 and 13.5 dBi have been obtained at 41.5 GHz, respectively, from the simulations of single and multi-lens antennas.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2073-2075
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• 2004

본 논문에서는 nonradiative dielcctric (NRD) 도파로를 이용하여 28GHz대에서의 single balanced mixer를 설계하였다. 혼합기에 필요한 $90^{\circ}$ hybrid direction기 3dB 결합기를 NRD 도파로를 이용하여 설계 하였고 CST MWS를 이용하여 설계 결과를 검중 하였으며 결과는 중심 주파수 28GHz에서 대역폭이 1GHz의 결합기를 설계하였음을 확인할 수 있었다. 이와동시에 다이오드를 부착하기 위해 NRD 도파로와 마이크로스트립의 매칭 구조를 1 pole UDR과 patch를 이용하여 혼합기를 설계, 제작하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2235-2236
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• 2008

본 논문에서는 초전도 전류제한기의 전압, 전류 등급증대를 위한 방안으로 자기결합을 이용한 초전도 전류 제한기의 특성을 분석하였다. 1차 코일과 초전도 소자가 연결된 2차 코일이 자기적으로 결합된 구조로서 사고가 발생되면 초전도 소자에 흐르는 전류가 임계전류 값을 넘게 될 경우 초전도 소자의 ��치로 인한 저항 발생으로 사고 전에 억제되었던 철심내부 자속이 발생하여 각 코일에 전압이 유기되며 이로 인해 사고 전류가 제한되는 특성을 가지고 있다. 자기결합을 이용한 초전도 전류 제한기의 용량을 증대시키기 위해서는 초전도 전류제한기의 2차권 선수를 작게 하는 것이 각 초전도 소자들의 전압부담을 균일하게 유지하고, 발생저항을 작게 하여 소자의 전력부담을 줄일 수 있다는 것을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.883-885
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• 2005

지지 벡터 기계(Support Vector Machine: SVM)를 이용한 다중부류 분류기법이 최근 활발히 연구되고 있다. SVM은 이진분류기이기 때문에 다중부류 분류를 위해서 다수의 분류기를 구성하고 이들을 효과적으로 결합하는 방법이 필요하다. 본 논문에서는 기존의 정적인 다중분류기 결합 방법과는 달리 포섭구조의 분류모델을 확률에 따라 동적으로 구성하는 방법을 제안한다. 확률적 분류기인 나이브 베이즈 분류기(NB)를 이용하여 입력된 샘플의 각 클래스에 대한 확률을 계산하고, OVA (One-Vs-All) 전략으로 구축된 다중의 SVM을 획득된 확률에 따라 포섭구조로 구성한다. 제안하는 방법은 OVA SVM에서 발생하는 중의적인 상황을 효과적으로 처리하여 고성능의 분류를 수행한다. 본 논문에서는 지문분류 문제에서 대표적인 NIST-4 지문 데이터베이스를 대상으로 제안하는 방법을 적용하여 $1.8\%$의 거부율에서 $90.8\%$의 분류율을 획득하였으며, 기존의 결합 방법인 다수결 투표(Majority vote), 승자독식(Winner-takes-all), 행동지식공간 (Behavior knowledge space), 결정템플릿(Decision template) 등보다 높은 성능을 확인하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.47-52
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• 2011

Nano-scale power splitter based on Si plasmonic waveguides are designed by utilizing the multimode interference (MMI) coupler. Effective dielectric method and longitudinal modal transmission-line theory are used for simulating the light propagation and optimizing the structural parameters at 3-D guiding geometry. The designed $1{\times}2$ 50:50 MMI power splitter has a nano-scale size of only $800nm{\times}850nm$. In order to achieve a variable power splitting ratio, a $2{\times}2$ MMI coupler is designed and the corresponding power splitting ratio can be tuned in the range of 78.5%:15.5%~5.5%:86.6%. Also, it is shown that it has a large bandwidth of $1.5{\mu}m{\sim}1.7{\mu}m$. In this range, the transmission is over 0.8.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.263-264
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• 2008