• Journal of Institute of Control, Robotics and Systems
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• v.20 no.12
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• pp.1196-1203
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• 2014

Recently, UFRs (Unmanned Flying Robots) have begun to be utilized in various areas for civilian and military applications. Due to this increased utilization, accidents involving UFRsare also increasing. To prevent or monitor accidents caused by UFRs, high-accuracy positioning information is one of the most important technical elements. This paper proposes an efficient UFR monitoring system which provides accurate UFR positioning information with low-cost onboard elements; a small ARM module based on an embedded Linux operating system, a low-cost single frequency GPS receiver with a cheap patch antenna, and a versatile wireless network interface module. The ground monitoring system employs a dual frequency GPS receiver to generate exact UFR coordinates with cm-level accuracy. By processing the UFR measurements based on the Inverse RTK (Real Time Kinematic) method, the ground monitoring system determines the cm-level accurate coordinates of the UFR. The feasibility of the proposed UFR monitoring system was evaluated by three experiments in terms of data loss and accuracy.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.11 no.2
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• pp.79-87
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• 1993

Executing various constructions and national land planning, it has rised importance how to acquire 3-dimensional geographical information efficiently. In conjunction with this, the concerned parties are interested in the accuracy of GPS positioning and applications. This study suggest the efficiency and possibility to apply geographical information construction by kinematic GPS surveying as comparing kinematic GPS results with triangulation, trilateration and static GPS results. In this study, we try to compare static with kinematic and can determine 3-D positions with difference of 6 mm in distance, 2"/10,000-4"/10,000, 20 cm in latitude, longitude and height at local area. In addition, difference from conventional surveying is about 1"/l0,000-3"/10,000 in horizontal. Therefore it is expected to apply kinematic GPS to make out topographic map and to construct data base associated with GIS.associated with GIS.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.3
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• pp.15-20
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• 2007

Low temperature processed ZnO-TFTs on glass below $270^{\circ}C$ for plastic substrate applications were fabricated and their electrical properties were investigated. Films in ZnO-TFTs with bottom gate configuration were made by RF magnetron sputtering system except for $SiO_2$ gate oxide deposited by ICP-CVD. ZnO channel films were grown on glass with various Ar and $O_2$ flow ratios. All of the fabricated ZnO-TFTs showed perfectly the enhancement mode operation, a high optical transmittance of above 80% in visible ranges of the spectrum. In the ZnO-TFTs with pure Ar process, the field effect mobility, threshold voltage, and on/off ratio were measured to be $1.2\;cm^2/Vs$, 8.5 V, and $5{\times}10^5$, respectively. These characteristic values are much higher than those of the ZnO-TFTs of which ZnO channel layers were processed with additional $O_2$ gas. In addition, ZnO-TFT with pure Af process showed smaller swing voltage of 1.86v/decade compared to those with $Ar+O_2$ process.

• Elastomers and Composites
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• v.45 no.3
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• pp.212-216
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• 2010

The materials of the lithium ion battery gasket require chemical resistance to the electrolyte, electrical insulating, compression set, anti-contamination and heat resistance. To estimate suitability for rubber which has better performance to compression set than PFA, each compound were made with various rubbers, such as EPDM, NBR, FKM, FVMQ, VMQ and we checked the characteristics of each compound. Samples from each compound was deposited in Propylene Carbonate and tested for changing of Hardness and Volume during 1,000 hr with $80^{\circ}C$. EPDM and VMQ showed good performance to chemical resistance to the electrolyte, and also we could get the values over $10^{10}{\Omega}cm$ on volume resistance basis in electrical insulating. EPDM and VMQ were judged as the most suitable material.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.180-187
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• 1997

$La_{0.68}Ca_{0.32}Cr_{0.97}O_{3}$ interconnector films ior pimar rypn solid oxide fuel (,ells were prepared under various sinteririg conditions and their bending strength. relative ilerisit~. m t l c:lec ~ ~ - i i ; i l condl~cti\.lt\ were niexiureti in order to study their mechanical and electrical propertics Th' Irndirig sriength of $La_{0.68}Ca_{0.32}Cr_{0.97}O_{3}$ lt the room temperature \vas increased with increasing sinrering temperature dnfl tinic. The relative densit\- of more than 94% was ohtained 1)). sintering at $1400^{\circ}C$ for 5hrs. The present irlvestigiition rovcals thcit sirileririg of $La_{0.68}Ca_{0.32}Cr_{0.97}O_{3}$ at lorn. temperature xyvas greatly assisted by formation oi Ca,,,(CrO,),, Also the i,leitriczl conductivity at $1000^{\circ}C$ \vas more than 100S; cm d t e r heating at $1400^{\circ}C$ for 7hrs.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.1
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• pp.13-16
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• 2017

$SnO_2$ single layer films and 2 nm thick Ni thin film intermediated $AZO/Ni/SnO_2$ trilayer films were deposited on glass substrate at room temperatures by RF and DC magnetron sputtering and then the optical and electrical properties of the films were investigated to enhance opto-electrical performance of $SnO_2$ single layer films. As deposited $SnO_2$ films show the optical transmittance of 81.8% in the visible wavelength region and a resistivity of $1.2{\times}10^{-2}{\Omega}cm$, while $AZO/Ni/SnO_2$ films show a lower resistivity of $5.8{\times}10^{-3}{\Omega}cm$ and an optical transmittance of 77.1% in this study. Since $AZO/Ni/SnO_2$ films show the higher figure of merit than that of the $SnO_2$ single layer films, it is supposed that the $AZO/Ni/SnO_2$ films can assure high opto-electrical performance for use as a transparent conducting oxide in various display applications.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.221-230
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• 2023

The liquefaction of soil occurs when a soil loses strength and stiffness because of applied stress, such as an earthquake or other changes in stress conditions that result in a loss of cohesion. Hence, a method for improving the strength of liquefiable soil needs to be developed. Many techniques have been presented for their possible applications to mitigate liquefiable soil. Recently, alternative methods using biopolymers (such as xanthan gum, guar gum, and gellan gum), nontraditional additives, have been introduced to stabilize fine-grained soils. However, no studies have been done on the use of carrageenan as a biopolymer for soil improvement. Due to of its rheological and chemical structure, carrageenan may have the potential for use as a biopolymer for soil improvement. This research aims to investigate the effect of adding carrageenan on the soil strength of treated liquefiable soil. The biopolymers used for comparison are carrageenan (as a novel biopolymer), xanthan gum, and guar gum. Then, sand samples were made in cylindrical molds (5 cm × 10 cm) by the dry mixing method. The amount of each biopolymer was 1%, 3%, and 5% of the total sample volume with a moisture content of 20%, and the samples were cured for seven days. In terms of observing the effect of temperature on the carrageenan-treated soil, several samples were prepared with dry sand that was heated in an oven at various temperatures (i.e., 20℃ to 75℃) before mixing. The samples were tested with the direct shear test, UCS test, and SEM test. It can increase the cohesion value of liquefiable soil by 22% to 60% compared to untreated soil. It also made the characteristics of the liquefiable increase by 60% to 92% from very loose sandy soil (i.e., ϕ=29°) to very dense sandy soil. Carrageenan was also shown to have a significant effect on the compressive strength and to exceed the liquefaction limit. Based on the results, carrageenan was found to have the potential for use as an alternative biopolymer.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.273-278
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• 2012

$ZrB_2$ has a melting temperature of $3245^{\circ}C$ and a low density of $6.1\;g/cm^3$, which makes this a candidate for application to ultra-high temperature over $2000^{\circ}C$. Beside these properties, $ZrB_2$ has excellent resistance to thermal shock and oxidation compared with other non-oxide engineering ceramics. This paper reviewed briefly 2 research examples, which are related to densification and properties of $ZrB_2$-based ceramics for ultra-high temperature applications. In the first section, the effect of $B_4C$ addition on the densification and properties of $ZrB_2$-based ceramics is shown. $ZrB_2$-20 vol.% SiC system was selected as a basic composition and $B_4C$ or C was added to this system in some extents. With sintered bodies, densification behavior and hightemperature (up to $1400^{\circ}C$) properties such as bending strength and hardness are examined. In the second section, the effect of the SiC size on the microstructures and physical properties is shown. $ZrB_2$-SiC ceramics are fabricated by using various SiC sources in order to investigate the grain-growth inhibition and the mechanical/thermal properties of $ZrB_2$-SiC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.412-417
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• 2022

Capacitive-type humidity sensors with a high sensitivity and fast response/recovery times have attracted a great attention in non-contact respiration biological signal monitoring applications. However, complicated fabrication processes involving high-temperature heat treatment for the hygroscopic film is essential in the conventional ceramic-based humidity sensors. In this study, a non-toxic ceramic/metal halide (BaTiO₃(BT)/NaCl) humidity sensor was prepared at room temperature using a solvent-free aerosol deposition process (AD) without any additional process. Currently prepared BT/NaCl humidity sensor shows an excellent sensitivity (245 pF/RH%) and superior response/recovery times (3s/4s) due to the NaCl ionization effect resulting in an immense interfacial polarization. Furthermore, the non-contact respiration signal variation using the BT/NaCl sensor was determined to be over 700% by maintaining the distance of 20 cm between the individual and the sensor. Through the AD-fabricated sensor in this study, we expect to develop a non-contact biological signal monitoring system that can be applied to various fields such as respiratory disease detection and management, infant respiratory signal observation, and touchless skin moisture sensing button.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.275-279
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• 2015

Poly(3,4-ethylenedioxythiophene) : poly(styrenesulfonate) (PEDOT : PSS) has attracted a great deal of attention as a transparent conductive material for organic solar cells or organic light-emitting diodes due to its high electrical conductivity, optical transparency, and excellent mechanical flexibility. It is well known that a solvent doping for PEDOT : PSS thin-films significantly increases the conductivity of films. In this paper, the effect of various kinds of solvent doping and post-treatment on the electrical and structural properties of PEDOT : PSS thin-films is investigated. The solvent doping greatly increases the conductivity of PEDOT : PSS thin-films up to 884 S/cm. A further enhancement of the conductivity of PEDOT : PSS thin-films is achieved by the solvent post-treatment which raises the conductivity up to 1131 S/cm. The enhancement is mainly caused by the depletion of insulating PSS and forming conducting PEDOT-rich granular networks. Strong optical absorption peaks at the wavelength of 225 nm of PEDOT : PSS thin-films indicate the depletion of insulating PSS by post-treatment. We believe that the solvent post-treatment is a promising method to achieve highly conductive transparent PEDOT : PSS thin-films for applications in efficient, low-cost and flexible organic devices.