• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5A
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• pp.566-573
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• 2004

A variable optical attenuator with a bending-sensitive fiber (BSF) that can be used in optical networks is developed. The proposed BSF consists of inner core, outer core, center dip and cladding. The proposed BSF is also very sensitive to mechanical perturbation, such as bending and pressure, making the light propagating in the BSF easily controlled and attenuated. The fabricated fiber-type variable optical attenuator using the proposed BSF (VOAFB) consisted of the BSF in a rectangular rubber ring with a fixed bend radius (BR) in a steady state. The variable optical attenuator using the proposed BSF (VOAFB) was able to attenuate the optical power by more than about -38㏈ with the gradient -88.4［㏈$.$$cm^{-1}$ /］ at (1540∼1560nm) based m adjusting the mechanical pressure applied to the upper surface of the rectangular rubber ring with the bent BSF. According to the experimental results when using the proposed VOAFB, the optical power was easily controlled by adjusting mechanical pressure and produced an insertion loss of 0.68㏈, polarization loss of 0.5㏈, and return loss of less than -60㏈.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.107-113
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• 2008

This paper presents half wavelength partial H-plane filters with multiple attenuation poles using narrow H-plane slot of evanescent waveguide. The narrow H-plane slot operates as an admittance inverter o( the bandpass filter and, simultaneously, generates an attenuation pole at particular frequency. Therefore, proposed filters with attenuation poles are simply implemented without any additional coupling and extra modification of the structure. The number of attenuation poles of the filters equals to that of the H-plane slots. Moreover, proposed filters are compact waveguide filter since ones are embodied by partial H-plane waveguide which has 1/4 cross section of conventional waveguide. The third and fourth-order half wavelength filters having 4 and 5 attenuation poles, respectively, are designed in H-band and their frequency responses are confirmed by simulation and measurement.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.4
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• pp.17-24
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• 2000

To use the power line as the communication channel, we have analyzed channel characteristics with the noise data and signal attenuation levels measured on power lines per loom. In this paper, channel capacities are calculated in the best or the worst case noise states and signal attenuations on power lines for three kinds of network-topologies. Analyzed the channel capacity by the best and worst conditions, we concluded that the serious factors influenceing on the channel capacity are the length from a transmitter to a receiver and the network topology.

• 전기의세계
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• v.30 no.3
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• pp.146-151
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• 1981

본고의 내용은 다음과 같다. 1. 광섬유의 구조와 특성 2. Numerical Aperture(NA) 3. 편광현상(Polarization effect) 4. 신호의 감쇄 5. 투과 대여폭(Transmission Bandwidth)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.1005-1008
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• 2006

In this paper, we provide data of wireless environment in indoor for Bluetooth and wireless LAN systems. To accurately measure transmission characteristic for influence of the indoor wall, we used radiation measurement system with antennas. And various structure and material of the indoor wall are measured. Results of the measurement show that the attenuation of power is about $1\sim3dB$ for cement wall(25cm). In the case of cement wall with steel frame, the attenuation of power was increased using horizontal polarization but was not affect using vertical polarization.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.554-559
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• 2004

A novel miniaturized 2-pole band pass filter(BPF) is proposed and it has an overlapped hairpin and slot structure on the upper and bottom plane of microstrip lines. Due to the overlapped structure of a hairpin and a slot, the size of the proposed BPF is quite smaller than that of a general BPF having coupled lines. The size of the proposed BPF is reduced to 33 % comparing with the conventional λ/4 coupled BPF. The attenuation is improved by controlling the attenuation poles properly using the proposed structure. The proposed 2-pole BPF is fabricated with a narrow bandwidth(69 ㎒) at center frequency, 1.9 ㎓ which is difficult to make that narrow bandwidth in the conventional coupled lines due to impractical spacing. The design method in this paper can be applied to the design of other microwave circuits to reduce the size and improve the performances.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1071-1077
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• 2002

In this paper, we have studied the dependence of insertion loss of the pressed microstrip PBG ring consisting of coupled two microstrip lines. When the distance decreases, two or three attenuation poles are created by the coupling between the lines. Thus the pressed PBG ring exhibits a wide stop band and sharp cutoff characteristics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.11a
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• pp.219-222
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• 1991

오늘날 점점 “지능적인” 우주구조물과 기계적 시스템의 빠를 발견으로 인하여 자체 진단과 제어 능력을 가진 발전된 구조가 중요해지고 있다. 일반적으로 이들 구조물이 자연 상태에서 유연하게 분포되어 있으므로 분포된 동적 측정과 효과적인 진동감쇄가 이들의 수행에 필수적이 되고 있다. 이 분야에 대한 이론적 발전은 지난 20년간 꾸준히 이루어져 왔다.(중략)

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.83-91
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• 2012

An RF energy detector for spectrum sensing in TV white space transceiver is presented. It is based on an RF active filtering technique that comprises a low-noise amplifier with a frequency-translation high-pass filtering feedfoward loop, which attenuates the unwanted sideband energy and only passes the wanted band energy. Unlike the conventional architecture, a new architecture that can attenuate both sidebands at the same time is proposed. A simplified system modeling method is presented to assess the non-ideality effects on the RF energy detector performances. System behavioral simulations demonstrate that the proposed architecture can be instrumental for realizaing a RF energy detector circuit in CMOS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.95-98
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• 2002

전력선 통신 blocking filter용 자심 재료를 개발하기 위해서 MnO 24 mol%, ZnO 25 mol% and $Fe_{2}O_{3}$ 51 mol% 의 기본조성에 $MoO_{3}$, $SiO_{2}$, CaO를 첨가하여 $1350^{\circ}C$에서 대기압 상수 A를 7.8롤 고정하고 소결하여 미세구조를 제어하였으며 기본 조성에 $MoO_{3}$ 400 ppm, $SiO_{2}$ 100 ppm and CaO 200 ppm을 첨가한 경우 평균 입경 $25{\mu}m$ 의 균일한 결정립으로 구성된 미세구조를 얻었고 기공의 감소에 의한 치밀화로 $4.98g/cm^{2}$의 고밀도화가 이루어 졌다. 또한 소결체의 균일한 미세구조와 고밀도화로 인해서 8221(${25^{\circ}C}$, 1 KHz) 의 가장 높은 투자율 특성을 나타냈다. 시편의 온도가 증가함에 따라 투자율이 증가되어 ${110^{\circ}C}$에서 13904의 거대 투자융이 측정되었고, 코일의 인가주파수가 1 KHz에서 1 MHz까지 증가됨에 따라 최고 ${102^{\circ}C}$까지 시편 온도가 상승하였다. 가장 높은 투자율 특성을 나타낸 ferrite 코어를 사용하여 단상 및 3상용 블로킹 필터의 감쇄율을 측정한 결과 현재 국내의 전력선 통신용 주파수 대역으로 규정되어 있는 10 KHz ~ 450 KHz 대역에서 각각 -46.46 dB와 -73.9 dB의 최고 값을 얻었다.