• Korean Journal of Optics and Photonics
• /
• v.18 no.4
• /
• pp.280-285
• /
• 2007

Based on the multimode fiber taper, a mode size converter for effective optical beam coupling between laser and optical fiber or between the two different optical fibers has been proposed and demonstrated. The device has a multimode input end and a single mode output end. The influence of various parameters, including device structure and launching conditions, on the coupling efficiency has been theoretically analyzed. The theoretical results revealed that the gaussian beam can be coupled into a single mode fiber without considerable insertion loss. The proposed multimode fiber taper has been fabricated using heating and pulling equipment incorporating two micro-torches. Experimental results showed that an optical beam with $50\;{\mu}m$ of large beam size was effectively coupled into single mode fiber through the multimode fiber taper. The insertion loss of the device was 1.3 dB.

• KIPS Transactions on Software and Data Engineering
• /
• v.11 no.9
• /
• pp.371-380
• /
• 2022

Convolutional neural networks are widely used to manipulate data arranged in a grid, such as images. A general convolutional neural network consists of a convolutional layers and a fully connected layers, and each layer contains a nonlinear activation functions. This paper proposes a combined parametric activation function to improve the performance of convolutional neural networks. The combined parametric activation function is created by adding the parametric activation functions to which parameters that convert the scale and location of the activation function are applied. Various nonlinear intervals can be created according to parameters that convert multiple scales and locations, and parameters can be learned in the direction of minimizing the loss function calculated by the given input data. As a result of testing the performance of the convolutional neural network using the combined parametric activation function on the MNIST, Fashion MNIST, CIFAR10 and CIFAR100 classification problems, it was confirmed that it had better performance than other activation functions.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.24 no.3
• /
• pp.21-26
• /
• 2024

Design and fabrication method of W-band 12-way radial power combiner is proposed in this paper. The proposed structure is used with TE₁₀ to TEM mode converter, which is realized using 2-step impedance transformer. The pin structure for mode converter is well bonded to the housing so that environment conditions such as vibration or shock are not affected. Proposed W-band power combiner has less than 0.7 dB insertion loss and more than 13 dB return loss from 88 GHz to 98 GHz. The measured output isolations between each other are greater than 7.5 dB from 82 to 100 GHz and phase differences are less than 10 degree from 88 to 96 GHz. Proposed power combiner is expected compact radar and various applications requiring for high power and stable environment conditions.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.11
• /
• pp.2015-2021
• /
• 2017

Recently, a lot of attention is fallen to IoT(Internet of Things) for hyper-connected society and the number of unlicensed wireless device has been increasing. Thus, this paper analyzed the impact of unlicensed wireless device on the basis of 802.11ah on licensed LTE user equipment in 900 MHz frequency band for efficient frequency use. As the interference analysis method, Minimum Coupling Loss (MCL) method and Monte Carlo (MC) method were used. In case of one interferer, minimum separation distance between interferer and victim was calculated as about 22 m through the MCL method under the assumption of the worst case. The maximum number of interferer to meet the interference probability of 5% below within a cell radius of the victim was computed as about 3000 by using MC method based on statistical technique. The analysis method and results in this paper are expected to be used for the coexistence between unlicensed wireless device and licensed wireless device.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.7
• /
• pp.761-770
• /
• 2008

Impedance or admittance inverter is a conceptual 2-port device frequently used in microwave filter design. In this paper, the equivalent circuit using inverter for general loss less 2-port circuit is presented. Our equivalent circuit can be directly and easily represented with z- or y-parameters compared with the conventional methods. Based on the representation, the derived results for various coupled lines such as parallel coupled line and anti-parallel coupled lines are compared ours. In addition, the results of other workers for improvement of the distortion in frequency response of microstrip coupled line filter are derived using our representation and compared. The proposed equivalent circuit shows the difference with conventional equivalent circuit so the conventional design method can not be applied to parallel coupled line filter with our representation. So in this paper the novel design method is proposed and we showed the method yields more accurate design results.

• Proceedings of the Optical Society of Korea Conference
• /
• 2002.07a
• /
• pp.170-171
• /
• 2002

근래에 광통신의 속도가 10Gbps 이상 증가하면서, 고려하지 않았던 편광과 관련된 현상이 원거리 광통신 시스템에 많은 문제점을 유발하게 되었다. 특히 편광의존손실(PDL)은 시스템의 BER과 신호 왜곡을 가중시켜 시스템 성능을 저하시킨다. 이러한 PDL을 시스템 상에서 보정하는 것은 매우 복잡하고 어렵기 때문에 광 부품 제조 단계에서 PDL을 작게 되도록 해야하며, 이를 위해 정확한 PDL을 측정이 요구된다. (중략)

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1992.06a
• /
• pp.164-167
• /
• 1992

본 고에서는 후천적인 청각 장애나 노령화 및 산업화에 따라 난청자가 증가하고 있는 현대사회에서 난청자를 위한 통화대책을 강구하고자, 청각과 전화 통화와의 관계, 청력손실의 측정방법, 전화통화의 입장에서 본 난청의 분류, 청각 장애에 따른 청각 특성에 대해서 총괄하였다. 그리고 난청자가 전화통화를 하고자 할 때 청력손실의 정도와 장애 부위에 따른 통화방법을 고찰하였다. 여기에서는 가벼운 정도의 난청자인 경우에는 최저 가청한계를 고려한 고음향 출력 전화기, 또 난청의 정도가 심한 난청자는 골도 청각을 이용한 골도 전화기가 유용한 통화수단임을 소개하였다. 또한 CCITT 및 외국에서 적극적으로 검토하고 있는 문제로서, 보청기 착용자가 사회와 접촉하기 위한 수단인 보청기와 전화기의 결합 방법을 종합 검토하였다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2001.02a
• /
• pp.44-45
• /
• 2001

실리카 마이크로 스피어는 손실이 대단히 적은 초고품위 공진기로 알려져 있다. 최근의 실험들에 의하면 실리카 마이크로 스피어는 공진기 Q 값이 $10^{9-10}$ 정도인데, 이는 현재까지 만들어진 마이크로 공진기들 중에서 가장 높은 값이다. 최근 마이크로 스피어는 저손실의 공진기로서 문턱조건이 없는 레이저 연구에 활용되고 있으며, 레이저와 좁은 공명 모드 선폭을 이용하여 레이저 주파수 안정화 및 광섬유 결합기 등에 활용되고 있다. 또한 Cavity-QED 연구와 Cavity-QED 효과를 이용한 소수의 양자점 레어저 연구에도 활용도고 있다. (중략)략)

• Proceedings of the Korean Vacuum Society Conference
• /
• 1995.06a
• /
• pp.81-82
• /
• 1995

약한 자장을 사용하는 평면형 유도 결합 플라즈마 식각 장치에서 라디카르이 농도 제어를 위하여 벽면온도를 증가시켜 라디칼 손실을 줄였다. 폴리머를 잘 형성하는 C4F8의 경우 이에 따라 식각 특성이 25%정도 개선되었고, OES(opptical emission sppectroscoppy)와 AMS(appearance mass sppectroscoppy)를 이용하여 라디칼과 이온의 밀도 변화를 측정하여 식각 결과를 설명할 수 있었으며, 반면에 CF4의 경우 큰변화를 볼 수 없었다.

• Polymer(Korea)
• /
• v.28 no.3
• /
• pp.281-284
• /
• 2004

비닐 형태의 부가중합에 의해 생성된 비결정 폴리노보넨은 주사슬이 고리화합물로 이루어져 있으며, 높은 고체밀도와 유리 전이 온도를 나타내며, 낮은 유전상수를 가지는 특징이 있다. 광학적으로 폴리노보넨은 낮은 투과손실을 가지고 있는데, 광통신 대역인 850 nm에서 삽입 손실이 0.1 dB/cm이고, 복굴절이 0.001을 나타내어 광결합 소자 및 광소자에 응용이 기대된다. 이는 주사슬의 고리화합물에 의해 결정화되지 않아, 유리 전이 온도가 28$0^{\circ}C$로 높으면서 비결정의 투명성을 가지기 때문이다.