• Journal of Magnetics
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• 제20권1호
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• pp.57-61
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• 2015

In this paper wireless power transmission system based on magnetic resonance coupling circuit was carried out. With the research objectives based on the mutual coupling model, mathematical expressions of optimal coupling coefficients are examined. Equivalent circuit parameters are calculated by Maxwell software, and the equivalent circuit was solved by Matlab software. The power transfer efficiency of the system was derived by using the electrical parameters of the equivalent circuit. System efficiency was analyzed depending on the different air gap values for various characteristic impedances. Hence, magnetic resonance coupling involves creating a resonance and transferring the power without radiating electromagnetic waves. As the air gap between the coils increased the coupling between the coils were weakened. The impedance of circuit varied as the air gap changed, affecting the power transfer efficiency.

• 대한전자공학회논문지
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• 제16권4호
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• pp.22-26
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• 1979

LED나 laser diode와 optical fiber의 coupling efficiency를 높이기 위해서는 lens의 곡율반경을 작게 하는 것이 효과적이다. 본 연구에서는 heating and pulling 반경에 의한 tapered lens를 고안함으로써 최적 size의 lens 제작을 용이하게 하였으며, taper의 특성을 이용하여 고효율 coupling을 가능하게 하였다. 이론적 계산에 의하여 90%까지의 light coupling이 가능함을 보였으며, 실험결과 flat end에 대한 improvement factor는 LED에서 3dB, laser diode에서 6dB까지 증가시킬 수 있었다. epoxy를 사용하여 LED에 pigital을 부착한 결과 온도특성 및 기계적 안정성에서 실용화에 충분할 정도로 우수하였다.

• Current Optics and Photonics
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• 제4권3호
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• pp.229-237
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• 2020

In this study, a beam-coupling system is designed to improve the coupling efficiency of achip-integrated spectrometer when the waveguide is arranged in a linear and discrete manner. In the proposed system the beam is shaped to be anti-Gaussian, to deposit adequate energy in the edge waveguides. The beam is discretely coupled to the corresponding waveguide by a microlens array, to improve the coupling efficiency, and is compressed by a toroidal lens to match the linear discrete waveguides. Based on the findings of this study, the coupling efficiency of the spectrometer is shown to increase by a factor of 2.57. Accordingly, this study provides a reference basis for the improvement of the coupling efficiency of other similar spectrometers.

• 전기전자학회논문지
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• 제23권1호
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• pp.306-309
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• 2019

Wireless charging is a technology of transmitting power through an air gap to an electrical load for the purpose of energy dissemination. Compared to traditional charging with code, wireless power charging has many benefits of avoiding the hassle from connecting cables, rendering the design and fabrication of much smaller devices without the attachment of batteries, providing flexibility for devices, and enhancing energy efficiency, etc. A transmitting coil and a receiving coil for inductive coupling or magnetic resonant coupling methods are available for the near field techniques, but are not for the far field one. In this paper, the wireless power transfer (WPT) circuit by using magnetic resonant coupling method with a resonant frequency of 13.45 Mhz for the low power system is implemented to measure the power transmission efficiency in terms of mutual distance and omnidirectional angles of receiver.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1362-1369
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• 2018

A method aimed at improving the beam-wave interaction efficiency by changing the coupling slot configuration has been proposed in the study of extended interaction oscillators (EIOs). The dispersion characteristics, coupling coefficient and interaction impedance of the high-frequency structure based on different types of coupling slots have been investigated. Four types of coupled cavity structures with different layouts of the coupling slots have been compared to improve the beam-wave interaction efficiency, so as to analyze the beam-wave interaction and practical applications. In order to determine the improvement of the coupling slot to a coupled cavity circuit in an EIO, we designed four nine-gap EIOs based on the coupled cavity structure with different coupling slot configurations. With different operating frequencies and voltages takes into consideration, beam voltages from 27 to 33 kV have been simulated to achieve the best beam-wave interaction efficiency so that the EIOs are able to work in the $2{\pi}$ mode. The influence of the Rb and the ds on the output power is also taken into consideration. The Rb is the radius of the electron beam, and the ds is the width of the coupling slot. The simulation results indicate that a single-slot-type EIO has the best beam-wave interaction efficiency. Its maximum output power is 2.8 kW and the efficiency is 18% when the operating voltage is 31 kV and electric current is 0.5 A. The output powers of these four EIOs that were designed for comparison are not less than 1.7 kW. The improved coupling-slot configurations enables the extended interaction oscillator to meet the different engineering requirements better.

• Journal of the Optical Society of Korea
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• 제20권2호
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• pp.291-299
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• 2016

We have investigated the ultimate limits of nonuniform grating couplers (NGCs) for optimized fiber coupling to silicon waveguides, compared to uniform grating couplers (UGCs). Simple grating coupler schemes, which can be fabricated in etching steps of the conventional complementary metal-oxide semiconductor (CMOS) process on silicon-on-insulator (SOI) wafers without forming any additional overlay structure, have been simulated numerically and demonstrated experimentally. Optimum values of the grating period, fill factor, and groove number for ultimate coupling efficiency of the NGCs are determined from finite-difference time-domain (FDTD) simulation, and confirmed with experimentally demonstrated devices by comparison to those for the UGCs. Our simulated results indicate that maximum coupling efficiency of NGCs is possible when the minimum pattern size is below 50 nm, but the experimental value for the maximum coupling efficiency is limited by the attainable fabrication tolerance in a practical device process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.132-136
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• 2002

Optical collimating lenses are play a role as maintenance parallel light and as a kind of optical collimating lens, there is Ball lenses, GRIN-rod lenses, spherical lenses and aspherical lenses etc. but recently GRIN lens has monopolized a market. The performance of optical collimator depended on the coupling efficiency. In this paper, we were compared and analyzed to be measured values of coupling efficiency with respect to optical working distance using GRIN rod lenses and spherical lenses. In the case of GRIN lenses with a beam size of 420 ${\mu}{\textrm}{m}$, the minimum coupling efficiency was obtained to a measured value of 0.15 ㏈ and in the case of spherical lenses was obtained to a measured value of 0.12 ㏈ on the same condition. In results, we found that a performance of spherical lenses be better as compared with a that of GRIN lens.

• 한국세라믹학회지
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• 제40권10호
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• pp.1021-1026
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• 2003

탄소재의 수지함침은 탄소재 표면 상태에 영향을 받는다. Coupling처리에 의한 탄소재 표면처리는 수지와의 호환성과 젖음성을 개선시켜 함침효율과 물성을 향상시킨다. 본 연구에서는 표면개질을 위해 탄소재를 실란 coupling 처리하였다. FT-IR 관찰결과 실라놀은 탄소재 표면에 단층으로 코팅되었음을 확인하였다. 탄소재의 coupling 처리는 함침효율을 향상시켜 기공율, 기계적 강도, 밀도, 마찰거동이 개선되었다.

• 전력전자학회논문지
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• 제21권6호
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• pp.542-545
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• 2016

This work proposes a capacitive coupling-based wireless battery charging circuit that is built with vehicle glasses for electric vehicles. A capacitive coupling wireless power transfer offers many advantages, such as low metal impact and low energy transfer efficiency changes in accordance with changes in position. However, a large coupling capacitor is needed for high power transfer. Therefore, a new capacitive coupling-based wireless power transfer LLC resonant converter built with the glasses of an electric vehicle is proposed. The proposed converter is composed of coupling capacitors with glasses of an electric vehicle and two transformers for impedance transformation. The proposed LLC converter can transfer large power and obtain high efficiency with zero voltage switching. The validity and features of the proposed circuit is verified by experimental results with a 1.2 kW prototype.

• 한국인터넷방송통신학회논문지
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• 제17권4호
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• pp.187-192
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• 2017

정확한 종방향 모드 전송선로 이론을 이용하여 비대칭 격자 구조형 방향성 결합기의 최대 전력전송 특성을 정확하게 분석하였다. 정확한 해석적 전송선로 수식과 대칭/비대칭 모드 사이의 간섭특성에 의존하는 결합효율을 정의하였으며, 전파 거리에 따른 TE 모드의 전력변화를 수치해석 하였다. 수치해석 결과, 비대칭 GADC에서 최대 전력전송은 전형적인 위상 정합조건 ${\Lambda}_{ph}$에서 발생하지 않았으며, 전파하는 중첩모드들의 삽입손실이 서로 같은 격자주기 ${\Lambda}_{eq}$에서 발생하였다. 더욱이, 격자의 비대칭 특성이 대칭 특성으로 변함에 따라 결합길이는 줄어들었으며, 전력전송 효율은 증가함을 보였다.