• Journal of Radiation Industry
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• v.2 no.1
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• pp.1-7
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• 2008

Active polymer gels expand and contract in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as biomimetic actuators and artificial muscles. In this study, poly (vinyl alcohol)(PVA) grafted acrylic acid monomer (PVA-g-AAc) hydrogels were prepared by $^{60}Co$ ${\gamma}-ray$ irradiation and their properties such as degree of grafting and weight swelling in electrostimulation as an artificial muscle and actuator were investigated.

• Electronics and Telecommunications Trends
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• v.36 no.3
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• pp.76-86
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• 2021

Technologies for lithium secondary batteries are now increasingly expanding to simultaneously improve the safety and higher energy and power densities of large-scale battery systems, such as electric vehicles and smart-grid energy storage systems. Next-generation lithium batteries, such as lithium-sulfur (Li-S) and lithium-air (Li-O₂) batteries by adopting solid electrolytes and lithium metal anode, can be a solution for the requirements. In this analysis of battery technology trends, solid electrolytes, including polymer (organic), inorganic (oxides and sulfides), and their hybrid (composite) are focused to describe the electrochemical performance achievable by adopting optimal components and discussing the interfacial behaviors that occurred by the contact of different ingredients for safe and high-energy lithium secondary battery systems. As next-generation rechargeable lithium batteries, Li-S and Li-O₂ battery systems are briefly discussed coupling with the possible use of solid electrolytes. In addition, Electronics and Telecommunications Research Institutes achievements in the field of solid electrolytes for lithium rechargeable batteries are finally introduced.

• International Journal of Aerospace System Engineering
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• v.9 no.1
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• pp.1-15
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• 2022

Pyrotechnic initiators provide a source of pyrotechnic energy used to initiate a variety of space mechanisms. Pyrotechnic systems build in electromagnetic environment that may lead to critical or catastrophic hazards. Special precautions are need to prevent a pulse large enough to trigger the initiator from appearing in the pyrotechnic firing circuits at any but the desired time. The EMC verification shall be shown by analysis or test that the pyrotechnic systems meets the requirements of inadvertent activation. The MIL-STD-1576 and two range safeties, AFSPC and CSG, require the safety margin for electromagnetic potential hazards to pyrotechnic systems to a level at least 20 dB below the maximum no-fire power of the EED. The PC23 is equivalent to NASA standard initiator and the 1EPWH100 squib is ESA standard initiator. This paper verifies the two safety margins for electromagnetic potential hazards. The first is verified by analyzing against a RF power. The second is verified by testing against a DC current. The EMC safety margin requirement against RF power has been demonstrated through the electric field coupling analysis in differential mode with 21 dB both PC23 and 1EPWH100, and in common mode with 58 dB for PC23 and 48 dB for 1EPWH100 against the maximum no-fire power of the EED. Also, the EMC safety margin requirement against DC current has been demonstrated through the electrical isolation test for the pyrotechnic firing circuits with greater than 20 dB below the maximum no-fire current of the EED.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.138-142
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• 2000

Thin film $LiNbO_3$MFS (metal-ferroelectric-semiconductor) capacitor showed improved characteristics such as low interface trap density, low interaction with Si substrate, and large remanent polarization. This paper reports ferroelectric $LiNbO_3$thin films grown directly on p-type Si (100) substrates by 13.56 MHz RF magnetron sputtering system for FRAM (ferroelectric random access memory) applications. RTA (rapid thermal anneal) treatment was performed for as-deposited films in an oxygen atmosphere at $600^{\circ}C$ for 60sec. We learned from X-ray diffraction that the RTA treated films were changed from amorphous to poly-crystalline $LiNbO_3$which exhibited (012), (015), (022), and (023) plane. Low temperature film growth and post RTA treatments improved the leakage current of $LiNbO_3$films while keeping other properties almost as same as high substrate temperature grown samples. The leakage current density of $LiNbO_3$films decreased from $10^{-5}$ to $10^{-7}$A/$\textrm{cm}^2$ after RTA treatment. Breakdown electric field of the films exhibited higher than 500 kV/cm. C-V curves showed the clockwise hysteresis which represents ferroelectric switching characteristics. Calculated dielectric constant of thin film $LiNbO_3$illustrated as high as 27.9. From ferroelectric measurement, the remanent polarization and coercive field were achieved as 1.37 $\muC/\textrm{cm}^2$ and 170 kV/cm, respectively.

• Macromolecular Research
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• v.11 no.6
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• pp.431-436
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• 2003

A new photoconducting polymer, diphenyl hydrazone-substituted polysiloxane, was successfully synthesized by the hydrosilylation method and characterized by FT-IR, $^1$H-NMR, and $^{29}$ Si-NMR spectroscopy. The glass transition temperature (T$_{g}$) of the polysiloxane having pendant diphenyl hydrazone was ca. 62 $^{\circ}C$, which enabled a component of a low-T$_{g}$ photorefractive material to be prepared without the addition of any plasticizers. This polysiloxane, with 1 wt% of $C_{60}$ dopant, showed a high photoconductivity (2.8 ${\times}$ 10$^{-12}$ S/cm at 70 V/${\mu}{\textrm}{m}$) at 633 nm, which is necessary for fast build-up of the space-charge field. A photorefractive composite was prepared by adding a nonlinear optical chromophore, 2-{3-[2-(dibutylamino)-1-ethenyl]-5,5-dimethyl-2-cyclohexenylidene} malononitrile, into the photoconducting polysiloxane together with $C_{60}$ . This composite shows a large orientation birefringence ($\Delta$n = 2.6 ${\times}$ 10$^{-3}$ at 50 V/${\mu}{\textrm}{m}$) and a high diffraction efficiency of 81 % at an electric field of 40 V /${\mu}{\textrm}{m}$.textrm}{m}$.EX>.

• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.55-59
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• 2007

Co-based amorphous magnetic wire with a diameter of $125{\mu}m$ and a length of 40 mm was used as an inner conductor of a coaxial cable to construct a magnetic sensor. Sensor characteristics was measured up to 3 GHz with applied up to 60 Oe by using network analyzer. Frequency dependence of impedance for this sensor was very close to the impedance resonant pattern of transmission line and 250 MHz was obtained as a 1/4 wavelength without external magnetic field. Large impedance change was measured in the magnetic field range between 0 Oe and 1 Oe, which was influenced by permeability change of magnetic amorphous wire. Because ${\Delta}Z/{\Delta}H$ value of $300{\Omega}/Oe$ was obtained at 0.1 Oe, this coaxial cable with amorphous wire can be useful as a magnetic sensor.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.951-956
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• 2011

CAN communication developed for communication between electric control devices in vehicle, was recently applied to automatic breaking devices, and can also be applied to field bus for production automation. Recently, field bus is introduced in engine control etc., for large ship. In this paper, cabin access control system is implemented, based on CAN communication. The cabin access control system based on CAN communication consists of access control server, embedded system based on ARM9, and micro-controller built-in CAN controller. The access control server can be able to manage overall access control system by accessing with manager. And embedded system adopted ARM9 processor transmits access information of RFID reader controller connected with CAN networks to server, also performs access control. The embedded system carry CAN frames to server, so it is used as gateway.

• Geophysics and Geophysical Exploration
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• v.8 no.2
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• pp.184-190
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• 2005

We have attempted to give some physical into the factors that control the response of subsurface target to plane wave excitation at VLF (very low frequency) frequencies. Although the VLF technique has some serious disadvantages, such as a lack of penetration depth and limited frequencies, its advantages are also extremely important to have made it by far the most popular electromagnetic technique in current use. In the magnetic-field measurement mode these lightweight, relatively low-priced tools allow us to survey large areas rapidly and inexpensively, to locate and roughly define subsurface electrical conductors. When used in the electric-field mode the technique is, in simple environments, capable of quantitative interpretation and once again the speed and relative cheapness of these devices makes them a natural 'first electromagnetic tool ' to use in reconnaissance mapping.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.617-621
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• 2009

Zinc oxide (ZnO) nanorods were grown on the pre-oxidized silicon substrate with the assistance of Au and the fluorine-doped tin oxide (FTO) based on the catalysts by vapor-liquid-solid (VLS) synthesis. Two types of ZnO powder particle size, 20nm, $20{\mu}m$, were used as a source material, respectively The properties of the nanorods such as morphological characteristics, chemical composition and crystalline properties were examined by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and field-emission scanning electron microscope (FE-SEM). The particle size of ZnO source strongly affected the growth of ZnO nanostructures as well as the crystallographic structure. All the ZnO nanostructures are hexagonal and single crystal in nature. It is found that $1030^{\circ}C$ is a suitable optimum growth temperature and 20 nm is a optimum ZnO powder particle size. Nanorods were fabricated on the FTO deposition with large electronegativity and we found that the electric potential of nanorods rises as the ratio of current rises, there is direct relationship with the catalysts, Therefore, it was considered that Sn can be the alternative material of Au in the formation of ZnO nanostructures.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.86.1-86.1
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• 2011

We are developing a new universal spectropolarimeter on the Domeless Solar Telescope (DST) at the Hida Observatory to realize precise spectropolarimetric observations in a wide range of wavelength in visible and near infrared. The system aims to open a new window of plasma diagnostics by using Zeeman effect, Hanle effect, Stark effect, impact polarization, and atomic polarization for measuring the external magnetic field, electric field, or an anisotropy in the excitation of the atoms. The polarimeter is a successor of formerly developed polarimeter on DST, which make possible to observe a polarization in a photospheric spectral line with polarimetric accuracy of 10-2 (Kiyohara et al. 2004). The new system consists of a 60cm aperture vacuum telescope, a high dispersion vacuum spectrograph, polarization modulator / analyzer composed of a rotating waveplate whose retardation is constant for a wide range of wavelength and Wallaston prism, and a fast and large format CCD camera or IR camera. Spectral images in both orthogonal polarizations are taken simultaneously with a frame rate of ~20Hz while the waveplate rotates continuously in a rate of 1rev./sec. Thus It takes 5 ~ 60 sec to observe polarization with accuracy of 10-3 in a wide wavelength range (400 - 1100nm). We also examined a polarimetric model of the telescope with accuracy of 10-3 to calibrate instrumental polarization on some wavelengths. In this talk, I will focus on the performance of the instrument.