• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.283-288
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• 2011

In this study, a wide-band photonic crystal Y-splitter for TE modes is proposed. A triangular lattice of air holes etched in a GaAs slab is used as the platform. In order to numerically analyze the structures, plane wave expansion (PWE) and finite difference time domain (FDTD) methods are used. In comparison with the structures reported in the literature, the proposed topology has a less complexity while it provides more than 100nm bandwidth. The simplicity of the design, its high transmission ratio and its wide bandwidth makes it a suitable choice for the implementation of photonic crystal integrated circuits.

• Journal of Magnetics
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• v.18 no.2
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• pp.178-182
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• 2013

We have developed a new non-conventional electron paramagnetic resonance (EPR) spectrometer, in which no resonant cavity was used. We previously demonstrated a wide frequency range operation of an EPR spectrometer using two loop antennas, one for a microwave transmission and the other for signal detection [1]. In contrast to Ref. [1], the utilization of a microstrip antenna as a transmitter enhanced a capability of wide-band operation. The replacement of conventional capacitors with varactor diodes makes resonance condition easily reproducible without any mechanical action during tuning and matching procedure since the capacitance of the diodes is controlled electronically. The operation of the new EPR spectrometer was tested by measuring a signal of 1,1-diphenil-2-picrylhydrazyl (DPPH) sample in the frequency range of 0.8-2.5 GHz.

• Current Optics and Photonics
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• v.3 no.5
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• pp.438-444
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• 2019

In this theoretical study, a line-defect photonic-crystal waveguide hosted in an annular photonic crystal was demonstrated to provide high-performance slow light with a wide band, low group-velocity dispersion, and a large normalized delay-bandwidth product. Combined with structural-parameter optimization and selective optofluid injection, the normalized delay-bandwidth product could be enhanced to a large value of 0.502 with a wide bandwidth of 58.4 nm in the optical-communication window, for a silicon-on-insulator structure. In addition, the group-velocity dispersion is on the order of $10^5$ ($ps^2/km$) in the slow-light region, which could be neglected while keeping the signal transmission unchanged.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.200-207
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• 2009

This paper presents a compact, low insertion loss, sharp rejection and wide band microstrip band pass filter that is composed rectangular loop resonator and Step-Impedance-Open-Stub(SIOS). The SIOS can be reduce length about 30 % more than general 0.25 $\lambda$ open stub. And the stub can the advantage of tuning impedance magnitude. In order to demonstrate agrement of this paper prove, the optimized wide band pass filters are realized and experimented. A transmission line model used to calculate the frequency response of the new filters shows good agreement with measurements. The filter has 3 dB fractional bandwidth of 51.75 %(3.206 GHz), an insertion loss of better than 0.44 dB from 4.587 GHz to 7.793 GHz, and two rejection of greater than 30 dB within 221 MHz($4.326{\sim}4.587\;GHz$) at low frequency band, 181 MHz($7.739{\sim}7.954\;GHz$) at high frequency band. Maximum rejection characteristics of the filter are -61.8 dB at low frequency and -76.3 dB at high frequency.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.39-44
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• 2005

A broadband DC to 40 GHz 5-bit MMIC digital attenuator has been developed. The ultra broadband attenuator has been achieved by newly inserted the transmission lines in conventional Switched-T attenuator and the optimization of the transmission line parameters. Momentum was employed in design for an accurate performance prediction at high frequencies and Monte Carlo analysis was applied to verify performance stability against the MMIC process variation. The attenuator has been fabricated with 0.15 $\mu$m GaAs pHEMT process. This attenuator has 1 dB resolution and 23 dB dynamic range. High attenuation accuracy has been achieved over all attenuation range and full 40 GHz bandwidth with the reference state insertion loss of less than 6 dB at 20 GHz. The input and output return losses of the attenuator are better than 14 dB over all attenuation states and frequencies.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.79-84
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• 1990

Analog systems could not fully deal with instrumentation and control facilities in power plants since these facilities have become more and more complex on account of various needs for large power generation capacity highly cost effective operation to conserve energy and operation management to prevent pollution. Digitalizations of control device and augmentations of control informations increased the necessity of fiber optic data networks which have excellent noise immunity and high quality wide-band with information transfer capability. The goal of this study is to offer a fiber optic data-way system which has high reliabilities, high data transmission rates and small cable ducts with large transmission capacities for the instrumentation and control of power plants.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.1
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• pp.40-44
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• 2006

In this paper, the distortion characteristics of an electrical pulse which has a rise/fall time due to the dispersion and the reflection, on nonuniform tapered microstrip lines has investigated in time domain. The transmission characteristics on uniform microstrip lines in time domain had represented already, but the results for the nonuniform tapered microstrip lines not represented yet. We investigated the transmission characteristics for pulse signal on the nonuniform tapered microstrip lines, and the result applied to design of wide band impedance matching circuit in design of MMIC. The voltage and current transfer functions are shown for the tapered line. The dispersion and distortion obtained by using these transfer functions are represented for the nonideal square pulse.

• Journal of Korea Multimedia Society
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• v.17 no.5
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• pp.573-581
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• 2014

The salient features of UWB(Ultra WideBand) networks such as high-rate communications, low interference with other radio systems, and low power consumption bring many benefits to users, thus enabling several new applications such as wireless universal serial bus (WUSB) for connecting personal computers (PCs) to their peripherals and the consumer-electronics (CE) in people's living rooms. Because the size of multimedia data frame, WiMedia device must transmit the fragment of MSDU. However, when the fragment of MSDU is lost, WiMedia device maintains active mode for the time to complete the transmission MSDU, and there is a problem that unnecessary power consumption occurs. Therefore we propose new power management scheme to reduce unnecessary power consumption of WiMedia devices in the case that the fragment is lost.

• ETRI Journal
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• v.27 no.3
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• pp.312-318
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• 2005

Mid-span spectral inversion (MSSI) has to utilize high optical pump power, for its operation principle is based on a nonlinear optical wavelength conversion. In this paper, a low pump-power operation of MSSI-based chromatic dispersion compensation (CDC) has been achieved successfully, for the first time to our knowledge, by introducing a noise pre-reduction scheme in cascaded wavelength conversions with periodically poled $LiNbO_3$ waveguides at a relatively low operation temperature. As preliminary studies, phase-matching properties and operation-temperature dependence of the wavelength converter (WC) were characterized. The WC pumped at 1549 nm exhibited a wide conversion bandwidth of 59 nm covering the entire C-band and a conversion efficiency of -23.6 dB at 11 dBm pump power. CDC experiments were implemented with 2.5 and 10 Gb/s transmission systems over 100 km single-mode fiber. Although it is well-known that the signal distortion due to chromatic dispersion is not critical at a 2.5 Gb/s transmission, the clear recovery of eye patterns was identified. At 10 Gb/s transmission experiments, eye patterns were retrieved distinctly from seriously distorted ones, and notable improvements in bit-error rates were acquired at a low pump power of 14 dBm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.621-629
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• 2001

In this thesis a wireless data transmission system has been proposed and analysed that uses the multi-carrier technique with the adaptive modulation scheme. In general, the OFDM(Orthogonal Frequency Division Multiplexing) system is assigning a same amount of information to all sub-carriers in a wireless data transmission. In the proposed system, the different amount of information is assigned to each sub-carrier depending on the state of channel and the target probability of error of system. With the proposed scheme, the transmission rate can be maximized with the fixed power and the required power to transmit the information can be minimized with the target probability of error of system.