• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.105.2-105.2
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• 2016

For the rational design and facile fabrication of novel nanostructures, we present a new approach to generating arrays of three-dimensionally tunable nanostructures by exploiting light-matter interaction. To create controlled three-dimensional (3D) nanostructures, we utilize the 3D spatial distribution of light, induced by the light-matter interaction, within the matter to be patterned. As a systematic approach, we establish 3D modeling that integrates the physical and chemical effects of the photolithographic process. Based on a comprehensive analysis of structural formation process and nanoscale features through this modeling, we are able to realize three-dimensionally tunable nanostructures using facile photolithographic process. Here we first demonstrate the arrays of three-dimensionally controlled, stacked nanostructures with nanoscale, tunable layers. We expect that the promising strategy would open new opportunities to produce the arrays of tunable 3D nanostructures using more accessible and facile fabrication process for various biomedical applications ranging from biosensors to drug delivery devices.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2127-2130
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• 2008

In this paper, a tunable bandpass filter with mutual inductive coupling circuits is newly designed and demonstrated for UHF TV tuner ranged from Ch.14(473MHz) to Ch.69(803MHz) applications. Conventional HF tuning circuit with an electromagnetic bandpass filter has several problems such as large size, high volume and high cost, since the electromagnetic filter is comprised of several passive components and air core inductors to be assembled and controlled manually. To address these obstacles, peaking chip inductor was newly applied for constructing the mutual inductive coupling circuit. The proposed circuit was newly and optimally designed, since the chip inductor showed lower components Q-value than the air core inductor. A varactor diode has been also used to fabricate the proposed tunable bandpass filter for RF tuning circuit. The fabricated tunable filter exhibited low insertion loss of approximately -3dB, high return loss of below -10dB, and large tuning bandwidth of 330MHz.

• Current Optics and Photonics
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• v.2 no.1
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• pp.96-100
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• 2018

A tunable low-phase-noise microwave generation structure that utilizes an optoelectronic oscillator (OEO) and a fiber Bragg grating (FBG) is proposed and experimentally demonstrated in this article. This structure has no particular requirement for the band width of the laser, and its tunability is realized through adjusting the central frequency of the tunable FBG. A detailed theoretical analysis is established and confirmed via an experiment. A high-purity microwave signal with a frequency tunable from 6 to 12 GHz is generated. The single-sideband phase noise of the generated signal at 10.2 GHz is -117.2 dBc/Hz, at a frequency offset of 10 kHz.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.95-99
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• 2006

In this paper, we proposed the new wavelength tunable filter for wide tunability of fiber ring laser. The proposed filter consists of the cascaded connection of Fiber Reflection Mach-Zehnder Interferometer and Sagnac filter or of hybrid filter and Fiber Reflection Mach-Zehnder Interferometer. The simulation shows that the continuous tunable range of 50nm can be obtained and that more stable single mode operation of ring laser can be expected due to narrow FWHM. of filter spectrum.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.586-589
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• 2012

In this paper, a tunable capacitor like an interdigital one is presented for low-voltage applications. In order to reduce operation voltage by enhancing fringing electric fields, two finger-patterned electrodes are vertically separated by employing a multi-layer thin film dielectric of a para-/ferro-/para-electrics without spacing between electrodes. The proposed tunable capacitor was fabricated on a quartz wafer and its characteristics are analyzed in terms of effective capacitance and tunability with a function of applied voltages, compared to the conventional interdigital capacitor (IDC). At 8V and 2 GHz, the proposed tunable capacitor shows the tunability of 18 % that is 10.3 % higher than that of the compared one.

• Journal of electromagnetic engineering and science
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• v.13 no.4
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• pp.245-250
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• 2013

This paper presents a tunable bandpass filter based on the varactor-loaded composite right- and left-handed transmission line (CRLH-TL). The proposed filter is composed of one CRLH-TL unit cell, which corresponds to the third-order bandpass filter. The tunable bandpass filter is designed using only lumped-elements. The use of lumped elements saves space and lowers the fabrication cost. The size of the proposed tunable bandpass filter is $17mm{\times}5mm$, neglecting the feed lines and DC lines. All of the varactors are controlled by one DC bias. The center frequency of the bandpass filter can be controlled by varying the value of the varactors. The tunable range of the center frequency is from 412.5 to 670 MHz. The insertion loss is less than 3 dB, the return loss is more than 10 dB in the passband.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.215-218
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• 2002

In this paper, we propose a microstrip line tunable phase shifter. If we vary the applied bias voltage, the relative dielectric constant of ferroelectrics also changes and we designed tunable phase shifter using Au/BSTO/MgO/Au structure. We also used a coupling structure to increase the amount of phase shift at certain frequency in a limited size and we could reduce the loss by reducing the line width.

• Electronics and Telecommunications Trends
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• v.39 no.1
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• pp.48-61
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• 2024

The integration of high-capacity terrestrial networks with non-terrestrial communication using satellites has become essential to support seamless low-latency services based on artificial intelligence and big data. Tunable light sources have been instrumental in resolving the complexity of channel management in wavelength division multiplexing (WDM) systems, contributing to increased network flexibility and serving as optical sources for long-distance coherent systems. Recently, these light sources have been applied to beam-steering devices in laser communication and sensing applications across ground, aerial, and satellite transport. We examine the utilization and requirements of tunable lasers in WDM networks and describe the relevant development status. In addition, performance requirements and development directions for tunable lasers used in optical interference systems and beam-steering devices are reviewed.

• Journal of IKEEE
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• v.14 no.4
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• pp.263-269
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• 2010

In this paper, we present high temperature characteristics of a tunable all-optical filter using fiber Bragg grating(FBG) filter in Ge doped and Ge & B co-doped fiber, including peak reflectivity, bandwidth and various normalized refractive index change with temperature variation. The reflection spectrum of a FBG filter with refractive index change is affected by its thermal stability. Consequently Ge doped FBG tunable filter has a better thermal stability than Ge & B co-doped FBG tunable filter. Also, both FBG tunable filters show good thermal stability up to about $500^{\circ}C$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.522-529
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• 2007

A semidynamic frequency divide-by-1.5 MMIC comprises a tunable polyphase filter, tunable image-rejection mixer, and a static divide-by-2 in the feedback path. Wideband suppression of unwanted tones is achieved by employing a tunable image-rejection mixer and a tunable single-stage polyphase filter. Implemented in GaInP/GaAs HBT technology, the divide-by-1.5 MMIC operates over the input frequency range of 4.5 to 9.2 GHz with better than -20 dBc suppressions of $1/3{\times}f_{in}\;and\;f_{in}$ tones, while dissipating 29 mA from 4.1 V supply.