• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.119-126
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• 2016

In this paper, we proposed the planar textile resonator for constructing wearable MR-WPT system and analyzed the characteristic of textile substrates used in resonators. The planar textile resonators were designed to resonate at 1-10 MHz. The loop and coil were fabricated planar structure on textile substrate using conductive materials. Polyester fiber and cotton widely used in real life were chosen as textile resonators for wearable applications and copper tape and silver paste were used for fabricating planar loop and coil on textile substrate. For comparison analysis on transfer efficiency according to the types of textile, transmitter and receiver parts were symmetric. According to the result, for the highest transfer efficiency of wearable WPT system, the planar resonators have specifications of relative thick textile substrate with low permittivity and low surface resistance of conductive pattern. The performed experiments show that the planar textile resonator is possible to be used for resonator in wearable MR-WPT system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.6980-6985
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• 2014

A micro-conductive pattern was fabricated on an insulating substrate ($SiO_2$) surface using a laser direct writing method. In the LIFT process, when the laser beam irradiates a thin metal film, the photon energy is absorbed by the film and converted to thermal energy, and the thermal decomposition reaction produced by the resulting heat conduction forms a deposit on the substrate. The resistivity of the micro-electrodes deposited through LIFT process with and without polymer coating was measured. The results showed that the electric conductivity of the micro-pattern and micro-structure can be increased approximatly two times when the deposited micropattern is fabricated through a LIFT process with a polymer coating, compared to the case without a polymer coating.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.41-45
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• 2021

In this study, in order to secure the high reliability of the memristor, we adopted a patterned lithium filament seed layer as the main agent for resistive switching (RS) characteristic on the 30 nm thick ZrO₂ thin film at the device manufacturing stage. Lithium filament seed layer with a thickness of 5 nm and an area of 5 ㎛ × 5 ㎛ were formed on the ZrO₂ thin film, and various electrode areas were applied to investigate the effect of capacitance on filament type memristive behavior in the parallel memristive circuit of memristor and capacitor. The RS characteristics were measured in the samples before and after 250℃ post-annealing for lithium metal diffusion. In the case of conductive filaments formed by thermal diffusion (post-annealed sample), it was not available to control the filament by applying voltage, and the other hand, the as-deposited sample showed the reversible RS characteristics by the formation and rupture of filaments. Finally, via the comparison of the RS characteristics according to the electrode area, it was confirmed that capacitance is an important factor for the formation and rupture of filaments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1114-1120
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• 2009

The conductivity of various electro-threads is analyzed, and the washable electro-thread embroidery UHF RFID tag antennas using the character shape without T-matching structure are designed by adding a T-matching structure. The RFID tag antenna using the electro-thread is easy to be embedded on a cloth as a wearable antenna because it is flexible and different from general copper inlay shape and tape type tag. The embroidery tag antennas are designed with the English alphabet 'F' and the Korea alphabet 'ㄹ' character. Those are easy to be applied to general clothes. The parameters of antennas are optimized and fabricated. The characteristics and the reading range patterns of the tag antennas are measured. The reading ranges of wet tags(tap water, sea water and soapy water) are tested and compared.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1071-1076
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• 2009

A wearable embroidery 'ㅂ' character shape UHF RFID tag antenna has been designed using conductive electro-thread. After testing characteristics of various electro-threads, the embroidery tag, with a T-matching structure, has been designed on a cloth with 200D(denier) electro-thread which performs electrically better. The embroidery tag on a piece of fabric or clothes made with the flexible electro-thread is a wearable tag and possible to be recognized by an RFID system. The conductivity of different deniers of electro-threads has been measured. The measured conductivity has been used for simulation and fabrication to have accurate simulation results. To verify the characteristics of the tag antenna, the return loss and reading range of the fabricated embroidery electro-thread UHF RFID tag antenna have been tested. The reading range is approximately 1.52 m.

• Journal of the Korean Graphic Arts Communication Society
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• v.26 no.1
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• pp.39-50
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• 2008

We have manufactured Ag pastes for gravure printing by adding different solvent contents. Then the gravure printability and properties of conductive patterns gravure-printed by the different rheology characteristics of pastes were investigated. The dispersity of pastes was increased and the viscosity and shear rate dependence of viscosity for pastes were decreased by increasing the solvent content. Also storage modulus G', loss modulus G" and angular frequency value when G" starts to be bigger than G' of pastes were increased by decreasing the solvent content. These mean a flow drop of paste. As a result of gravure printing using two plates which have different line counts(175line and 350line), conductive patterns printed using 175line were spreaded more but Ag packing, thickness and conductivity of the conductive patterns were better than those printed using 350line. And the spread values of conductive patterns were increased with solvent contents but the best properties for Ag packing, surface roughness and conductivity of the conductive pattern were obtained by paste (3) which has 550cps of viscosity at $100s^{-1}$ and tan ${\delta}$ > 1 at 10rad/s. As a result of gravure printing using 350 line plate and paste (3), the conductive pattern has $1.2{\mu}m$ of film thickness and $1.9{\times}10^{-5}{\Omega}{\cdot}cm$ of conductivity.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.6
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• pp.122-128
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• 2016

The Biosensor biosensor pattern was developed by via an EHD (electro-hydro-dynamics (EHD) patterning process that was performed under atmospheric pressure at room temperature in a single step. The drop diameter was smaller than nozzle diameter and applied high viscosity conductive ink was applied in the EHD patterning method to provide a clear advantage over the piezo and thermal inkjet printing techniques. The Biosensor's biosensor's micro electrode pattern was printed by via a continuous EHD patterning method using 3three- type types of control parameters parameter (input voltage, patterning speed, nozzle pressure). High viscosity (1000 cps) conductive ink with 75 wt% of silver nanoparticles was used for experimentation. The incremental result of impedance of biosensor impedance was measured between the antibody ($10ug{\mu}g/ml$) to spore (0.1 ng/ml, 10 ng/ml, and $1ug{\mu}g./ml$) reaction at frequency 493 MHz frequency.

• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.51-57
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• 1995

Indium Tin Oxide (ITO) thin films have been fabricated by the rf magnetron sputtering technique with a target of a mixture $In_{2}O_{3}$ (90mol%) and $SnO_{2}$ (10mol%). We prepared ITO thin films with substrate temperature 100, 200, 300, 400, $500^{\circ}C$ and post-annealing temperature 300, 400, $500^{\circ}C$. And we analyzed X -ray diffraction patterns, electrical properties, transmission spectra and SEM photographs. As a result, the crystallinity, electrical conductivity and transmittance of ITO thin films were improved with increasing substrate temperature. But, as increasing post-annealing temperature in air, conductivity of the film was decreased. When the ITO thin film was fabricated with substrate temperature of $500^{\circ}C$ and thickness of $3000{\AA}$, its resistivity and transmittance were about $2{\times}10^{-4}{\Omega}cm$ and 85% or more, respectively.

• Korean Journal of Materials Research
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• v.20 no.10
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• pp.513-517
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• 2010

There have been many efforts to modify and improve the properties of functional thin films by hybridization with nano-sized materials. For the fabrication of electronic circuits, micro-patterning is a commonly used process. For photochemical metal-organic deposition, photoresist and dry etching are not necessary for microscale patterning. We obtained direct-patternable $SnO_2$ thin films using a photosensitive solution containing Ag nanoparticles and/or multi-wall carbon nanotubes (MWNTs). The optical transmittance of direct-patternable $SnO_2$ thin films decreased with introduction of nanomaterials due to optical absorption and optical scattering by Ag nanoparticles and MWNTs, respectively. The crystallinity of the $SnO_2$ thin films was not much affected by an incorporation of Ag nanoparticles and MWNTs. In the case of mixed incorporation with Ag nanoparticles and MWNTs, the sheet resistance of $SnO_2$ thin films decreased relative to incorporation of either single component. Valence band spectral analyses of the nano-hybridized $SnO_2$ thin films showed a relation between band structural change and electrical resistance. Direct-patterning of $SnO_2$ hybrid films with a line-width of 30 ${\mu}m$ was successfully performed without photoresist or dry etching. These results suggest that a micro-patterned system can be simply fabricated, and the electrical properties of $SnO_2$ films can be improved by incorporating Ag nanoparticles and MWNTs.

• Journal of IKEEE
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• v.25 no.4
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• pp.607-612
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• 2021

This paper presents a novel CPW-fed UWB monopole paper antenna made by paper and copper tape. Through the simulation, the optimized antenna design parameters were obtained, and an antenna having an omni-directional radiation pattern and a gain of 2.2 dBi or more in the UWB frequency band of 3.1-10.6 GHz was designed. The antenna was manufactured using general A4 paper and copper tape, and the measurement result satisfies the return loss of -10dB or less in the UWB frequency band and confirm that the return loss characteristic was maintained even when the antenna plane was bent by 3 mm in the longitudinal direction. The proposed antenna is a wearable device that can provide services in the UWB band, and can be manufactured inexpensively by printing it with a conductive print on paper. So it can be used as a wearable antenna for UWB communication in various application fields such as logistics and disposable terminals.