• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.94-101
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• 2011

Various kinds of medical imaging devices have been studied to develop periapical radiography. However, there are some problems such as high x-ray exposure rate and pains for patients because of the problems caused by intra-oral sensor based radiography system. In this study, a new concept of periapical radiography, intra oral X-ray tube and detector system, is introduced to solve these problems. This system is made up of miniature X-ray tube based on subminiature thermal electron or cold electron, CMOS based detector, and a body including automatic position and system control devices. In order to confirm the possibility of proposed new concept to periapical radiography, miniature x-ray tube from XOFT corporation is used to develop new x-ray system, and the performance evaluation of this system is performed according to collimator. Also, dental images are compared after acquiring both images from existing system versus new concept of system. As a result, new concept of system showed excellent image. Thus, it is considered that new concept of system will have a significant effect on medical imaging technology.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.1
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• pp.15-22
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• 2014

This paper presents the implementation of a control system of pellet boiler using wood pellet as carbon neutral material. The system also has the additional features to provide remote controlling and monitoring based on home networking technology through either public switched telephone networks or mobile communication networks. It consists of three kinds of sub-modules; a main controller provides basic and additional features such as a setting of temperature, a supplying of wood pellet, a controlling of ignition and fire-power, and a removing of soot. The second is temperature controller of individual rooms which is connected to the main controller through RS-485 links. And interface modules with PSTN and mobile networks can support remote controlling and monitoring the functions. The test results under the heating area of $172m^2$ show a thermal efficiency of 93.6%, a heating power of 20,640kcal/hr, and a fuel consumption of 5.54kg/hr. These results are superior to those of the conventional pellet boilers. In order to obtain the such high performance, we newly applied a 3-step ignition flow, a flame detection by $C_dS$ sensor, and a fire-power control by fine controlling of shutter to our pellet boiler.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.239-246
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• 1999

A highly sensitive photovoltaic infrared photodiode was fabricated for detecting infrared light in $3{\sim}5\;{\mu}m$ wavelength range on InSb wafer with p-i-n structure grown by MOCVD. Silicon dioxide($SiO_2$) insulating films for the junction interface and surface of photodiode were prepared using RPCVD because InSb has low melting point and evaporation temperature. After formation of In ohmic contacts by thermal evaporation, the electrical properties of the photodiode were characterized in dark state at 77K. A product of zero-bias resistance and area($R_0A$) showed $1.56{\times}10^6\;{\Omega}{\cdot}cm^2$ that satisfied BLIP(background limited infrared photodetector) condition. When the photodiode was tested under infrared light, the normalized detectivity of about $10^{11}\;cm{\cdot}Hz^{1/2}{\cdot}W^{-1}$ was obtained. we successfully fabricated a unit cell with InSb IR array with good quantum efficiency and high detectivity.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.704-709
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• 1998

Non-linear optical polymer based on poly (${\alpha}$-methylstyrene-co-maleic anhydride) (MSMA) substrate polymer was prepared by polymer reaction method and its thermal and electro-optic properties were examined. In the polymer reaction between MSMA substrate polymer and 2-[4-(4-nitrophenylazo)-N-ethylphenylamino]ethanol (DR1) chromophore, the degree of substitution of DR1 into MSMA was higher with the 4-dimethylaminopyridine (DMAP) as catalyst and 3-dicyclohexyl carbodiimide (DCC) as dehydrating agent (sample, MSMA-DC) than the one with just 4-dimethylaminopyridine as catalyst (sample, MSMA-D). The synthesized NLO polymer (MSMA-DC) exhibited electro-optic coefficient of 18 pm/V (632.8 nm) and glass transition temperature ($T_g$) of about $175^{\circ}C$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.4_1
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• pp.363-371
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• 2014

Most space-borne optical scanning systems adopt linear arrayconfigurations. The well-knownthree different types of space-borne sensors arealong-track line scanner, across-track linescanner, and three line scanner. To acquire accurate location information of an object on the ground withthose sensors, the exterior and interior orientation parameters are critical factors for both of space-borne and airborne missions. Since the imaging geometry of sensors mightchange time to time due to thermal influence, vibration, and wind, it is very important to analyze the Interior Orientation Parameters (IOP) effects on the ground. The experiments based on synthetic datasets arecarried out while the focal length biases are changing. Also, both high and low altitudes of the imagingsensor were applied. In case with the along-track line scanner, the focal length bias caused errors along the scanline direction. In the other case with the across-track one, the focal length bias caused errors alongthe scan line and vertical directions. Lastly, vertical errors were observed in the case ofthree-line scanner. Those results from this study will be able to provide the guideline for developing new linearsensors, so as for improving the accuracy of laboratory or in-flight sensor calibrations.

• Journal of Korean Neurosurgical Society
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• v.30 no.7
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• pp.903-906
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• 2001

Objective : The brain temperature is about $0.4-1^{\circ}C$ higher than that of the other peripheral body area. But most of these results have been obtained in normothermic condition. The objective of this study is to evaluate the temperature difference between the brain and axilla, in patients under hypothermia. Methods : Sixty-three patients(37 women and 26 men) who underwent craniotomy with implantation of the thermal diffusion flowmetry sensor were included in this study. The temperature of the cerebral cortex and axilla was measured every 2 hours, simultaneously. The patient group was divided according to axillary temperature hyperthermia( over $38^{\circ}C$), normothermia($36-38^{\circ}C$) and hypothermia(under $36^{\circ}C$). Total 1671 paired sample data were collected and analyzed. Results : The temperature difference between the cerebral cortex and the axilla was $0.45{\pm}1.04^{\circ}C$ in hyperthermic patients, $0.97{\pm}1.1^{\circ}C$ in normothermic patients and $1.04{\pm}0.81^{\circ}C$ in hypothermic patients. The temperature difference has statistical significance in each group(unpaired t-test, p<0.05). Conclusion : From our study the temperature difference between the brain and the axilla in hypothermic condition increased more than that of normothermic state. And in hyperthermic condition, the temperature difference decreased.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.41-46
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• 2019

In order to develop novel thermal imaging materials for microbolometer applications, $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ ($0.18{\leq}x{\leq}0.26$) thin films were fabricated using metal-organic decomposition. Effects of Cu content on the electrical properties of the annealed films were investigated. Spinel thin films with a thickness of approximately 100 nm were obtained from the $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ films annealed at $380^{\circ}C$ for five hours. The resistivity (${\rho}$) of the annealed films was analyzed with respect to the small polaron hopping model. Based on the $Mn^{3+}/Mn^{4+}$ ratio values obtained through x-ray photoelectron spectroscopy analysis, the hopping mechanism between $Mn^{3+}$ and $Mn^{4+}$ cations discussed in the proposed study. The effects of $Cu^+$ and $Cu^{2+}$ cations on the hopping mechanism is also discussed. Obtained results indicate that $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ thin films with low temperature annealing and superior electrical properties (${\rho}{\leq}54.83{\Omega}{\cdot}cm$, temperature coefficient of resistance > -2.62%/K) can be effectively employed in applications involving complementary metal-oxide semiconductor (CMOS) integrated microbolometer devices.

• Design & Manufacturing
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• v.13 no.2
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• pp.17-21
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• 2019

In this study, selective laser sintered 3D printing mold core and metal core were used to investigate the difference of the thickness shrinkage from the gate of the injection molded part at a constant interval. SLS 3D printing mold core was made of nylon-based PA2200 powder and the metal core was manufactured by conventional machining method. As the PA2200 powder material has low strength, thermal conductivity and high specific heat characteristics compared with metal, molding conditions were set with the consideration of molten temperature and injection pressure. Crystalline resin(PP) and amorphous resin(PS) with low melting temperature and viscosity were selected for the injection molding experiment. Cooling time for processing condition was selected by checking the temperature change of the cores with a cavity temperature sensor. The cooling time of the 3D printing core was required a longer time than that of the metal core. The thickness shrinkage of the molded part compared to the core depth was measured from the gate by a constant interval. It was shown that the thickness shrinkage of the 3D printing core was 2.02 ~ 4.34% larger than that of metal core. In additions, in the case of metal core, thickness shrinkage was increased with distance from the gate, on the contrary, in the case of polymer core showed reversed aspect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.81-86
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• 2019

Metal oxide/graphene composites have been known as promising functional materials for advanced applications such as high sensitivity gas sensor, and high capacitive secondary battery. In this study, tin dioxide ($SnO_2$) nanostructures were grown on chemically synthesized graphene nanosheets using a two-zone horizontal furnace system. The large area graphene nanosheets were synthesized on Cu foil by thermal chemical vapor deposition system with the methane and hydrogen gas. Chemically synthesized graphene nanosheets were transferred on cleaned $SiO_2$(300 nm)/Si substrate using the PMMA. The $SnO_2$ nanostuctures were grown on graphene nanosheets at $424^{\circ}C$ under 3.1 Torr for 3 hours. Raman spectroscopy was used to estimate the quality of as-synthesized graphene nanosheets and to confirm the phase of as-grown $SnO_2$ nanostructures. The surface morphology of as-grown $SnO_2$ nanostructures on graphene nanosheets was characterized by field-emission scanning electron microscopy (FE-SEM). As the results, the synthesized graphene nanosheets are bi-layers graphene nanosheets, and as-grown tin oxide nanostructures exhibit tin dioxide phase. The morphology of $SnO_2$ nanostructures on graphene nanosheets exhibits complex nanostructures, whereas the surface morphology of $SnO_2$ nanostructures on $SiO_2$(300 nm)/Si substrate exhibits simply nano-dots. The complex nanostructures of $SnO_2$ on graphene nanosheets are attributed to functional groups on graphene surface.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.576-587
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• 2018

This study has focused on analysis factors affecting safety monitoring system at tailings sites, and the evaluation equipment to monitor the factors. Twenty sites at eighteen mines with unsafe conditions were selected to examine the equipment. There were three main factors influenced safety in the sites including surface erosion, piping, and slope instability. In detail, the surface erosion was divided into three sub-factors (planting, soil-topping layer, and tailings), piping into three sub-factors (liner, rain protection facility and leachate), and slop instability was also divided into three sub-factors (slop, concrete wall, and reinforcing wall). As results of in-field measurement, a CCTV was the most effective facility, and electrical resistivity survey, acoustic sensing, thermal liner sensor, structure inclinometer, rainfall meter, and flowmeter were also highly effective. According to applications of the facilities in the unstable tailings, structural defects were mainly found in the piping, which was the most important monitoring factor for safety management of tailings sites.