• Journal of the Korean Ceramic Society
• /
• v.41 no.1
• /
• pp.86-91
• /
• 2004

$LiCoO_2$ cathode powders with round particle shaped and nano grain sized of 70-300nm were synthesized by a mechanochemical method. The surface of Li-Co precursor prepared by freeze drying method was modified by $K_2SO_4$ coating and ball milling was used for the coating process. The precursor was crystallized to high temperature form of $LiCoO_2$ at $800^{\circ}C$ and the grain growth was inhibited by the $K_2SO_4$ coating effect. The $K_2SO_4$ coating was not decomposed at $800^{\circ}C$ and prevented the contact in the Li-Co precursor particles. The nano-sized $LiCoO_2$ powder had tetragonal phase and it affected the Li diffusion through the surface of particles. It means that the anode materials for hight performance battery should be satisfied not only small particle size but phase contol on the surface of particles. In this study, the powder characteristics and rate capabilities were compared with a commercial powder and the nano-sized $LiCoO_2$ powder fabricated by the mechanochemical method. And the crucial factor which affects on battery performance was also examined.

• Journal of Technologic Dentistry
• /
• v.33 no.1
• /
• pp.37-45
• /
• 2011

Purpose: Heat pressed ceramics, used for all ceramic restorations, have the additional advantage of being technically less change through using of the lost-wax technique. Conceptually, combining the ceramic with the clinically proven reinforcing ability of a metal framework would be advantageous; however, cause of mismatching of fusion between ceramics and metal frameworks which from differences of casting temperature and coefficient of thermal expansion, pressed ceramics could not be used with a metal framework. The purpose of this study was to compare shear bond strength of press-to metal ceramic to porcelain fused non precious metal and feldspatic porcelain fused non precious metal. Methods: The 30 metal specimens were casted in a porcelain fused non precious metal nickel-chromium alloy. They were divided into 3 groups by surface treatment and applied ceramic: $125{\mu}m$ aluminium oxide sandblasting and veneered feldspatic porcelain (group FP), $125{\mu}m$ aluminium oxide sandblasting and had press-to-metal ceramic applied (group PC), porcelain bonder (gold bonder) fused on surface of metal specimens and had press-to-metal ceramic applied (group PCG). In each group 10 metal specimens were used. The press-to-metal ceramic applied 20 specimens had ash-free wax pattern applied, the metal-wax complexes invested, and were pressed with heat press ceramic. All specimens were subjected to shear bond strength test at a crosshead speed of 1.0 mm/min. Results: The results of measured in Mean SD and data were analyzed by one-way AVOVA (p= .05) and Tukey HSD test (p= .05).: group FP $16.090{\pm}1.841$ MPa, group PC $12.620{\pm}1.8256$ MPa, group PCG $10.920{\pm}0.9283$, significant differences between all groups (p < .05). Significant differences were found in each between group FP and group PC, group FP and group PCG (p < .05). Conclusion: The shear bond strength of press-to-metal ceramic to porcelain fused non precious metal was described higher in unused gold bonder group than used gold bonder groups.

• Korean Chemical Engineering Research
• /
• v.50 no.3
• /
• pp.582-587
• /
• 2012

In this paper, it was studied on the crystallization characteristics of PLA film by adding ammonium phosphate (APP) as a nucleation agent. Crystallinity and crystallite size of PLA film were determined by Scherrer equation. Crystallization rate constant of PLA film was calculated through Avrami equation. Film samples in the study were prepared by two steps. PLA films were prepared by adding 1, 5, and 10 wt%, respectively, at first and was secondly annealed at 130, 140, and $150^{\circ}C$. Crystallinity of pure PLA film was average 4.6% and those of PLA film with adding 1, 5, and 10 wt% APP were 12.2, 47.7, and 50.0%, respectively. Crystallite size of PLA film was average 28.0 nm and those of PLA film with adding 1, 5, and 10 wt% APP were 26.8, 24.0, and 19.0 nm, respectively. Crystallization rate constants of PLA film with 1 wt% APP were 2.12, 3.86, and 0.27 by annealing at 130, 140, and $150^{\circ}C$, respectively, where was higher than pure PLA film and those with adding 5 and 10 wt% APP, respectively.

• Journal of the Microelectronics and Packaging Society
• /
• v.17 no.1
• /
• pp.33-39
• /
• 2010

Printing technologies have been indicated as alternative methods for patterning conductive, semi-conductive or insulative materials on account of their low-cost, large-area patternability and pattern flexibility. For application of the printing technologies in manufacture of semiconductor or display modules, ink or paste composed of nanoparticles, solvent and additives are basically needed. Here, we report recent advances in eco-friendly nano-ink technology for semiconductor and display technology. Then, we will introduce an eco-friendly ink formation technology developed in our group with an example of manufacturing $SiO_2$ nanopowders and inks. We tried to manufacture ultrafine $SiO_2$ nanoparticles by applying a low-temperature synthetic method, and then attempted to fabricate the printed $SiO_2$ film onto the glass substrate to see whether the $SiO_2$ nanoparticles are feasible for the printing or not. Finally, the electrical characteristics of the films were measured to investigate the effect of the manufacturing parameters.

• Convergence Security Journal
• /
• v.17 no.5
• /
• pp.41-47
• /
• 2017

The Marine Environment Observation Information System supplies oceanographic information elements such as water temperature, chlorophyll, float, etc. based on satellite images to consumers. The data produced by the Korean marine environmental observatories are located in the coastal areas of Korea. But if the range is too far from a particular area of interest, due to distance or spatial constraints, the accuracy and up-to-dateness of the data can not be relied upon. Therefore, it is necessary to perform fusion and complex operation to solve the difference between the field observation and the marine satellite image. In this study, we develop a system that can process marine environmental information in the user's area of interest in the form of layered character (numeric) information considering the readability and light weight rather than the satellite image. In order to intuitively understand satellite image information, we characterize (quantify) the marine environmental information of the area of interest and we process the satellite image band values into layered characters to minimize the absolute amount of transmitted / received data. Also we study modular location-based interest information service method to be able to flexibly extend and connect interested items that diversify various observation fields as well as application technology to serve this.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.31 no.1
• /
• pp.37-42
• /
• 2021

The effect of chemical composition on the structural and thermal properties of TiZrN thin films was studied. As the Zr fraction in the deposited TixZr1-xN (x = 0.87, 0.82, 0.7, 0.6, and 0.28) increased, microstructural changes consisted of reduction in the grain size and a gradual transition from columnar structure to granular structure were observed. In addition, it was also confirmed that a gradual crystal phase transition from TiN to TiZrN has occurred as the Zr fraction increased up to 0.4. After heat treatment at 900℃, Ti0.82Zr0.18N and Ti0.7Zr0.3N layers were converted to a form in which rutile phase TiO2 and TiZrO4 oxides coexist, while Ti0.6Zr0.4N layer was converted to TiZrO4 oxide. Among the five compositions of TiZrN films, the Ti0.6Zr0.4N showed the best high temperature stability and produced a significant enhancement in the thermal oxidation resistance of Inconel 617 through suppressing the surface diffusion of Cr caused by thermal oxidation of the Inconel 617 substrate.

• Nuclear Engineering and Technology
• /
• v.55 no.6
• /
• pp.2139-2146
• /
• 2023

During reactor operation, the divertor must withstand unprecedented simultaneous high heat fluxes and high-energy neutron irradiation. The extremely severe service environment of the divertor imposes a huge challenge to the bonding quality of divertor joints, i.e., the joints must withstand thermal, mechanical and neutron loads, as well as cyclic mode of operation. In this paper, potassium-doped tungsten (KW) is selected as the plasma facing material (PFM), oxygen-free copper (OFC) as the interlayer, oxide dispersion strengthened copper (ODS-Cu) alloy as the heat sink material, and reduced activation ferritic/martensitic (RAFM) steel as the structural material. In this study, a vacuum brazing technology is proposed and optimized to bond Cu and ODS-Cu alloy with the silver-free brazing material CuSnTi. The most appropriate brazing parameters are a brazing temperature of 940 ℃ and a holding time of 15 min. High-quality bonding interfaces have been successfully obtained by vacuum brazing technology, and the average shear strength of the as-obtained KW/Cu and ODS-Cu alloy joints is ~268 MPa. And a fabrication route for manufacturing the flat-type divertor target based on brazing technology is set. For evaluating the reliability of the fabrication technologies under the reactor relevant condition, the high heat flux test at 20 MW/m² for the as-manufactured flat-type KW/Cu/ODS-Cu/RAFM mockup is carried out by using the Electron-beam Material testing Scenario (EMS-60) with water cooling. This paper reports the improved vacuum brazing technology to connect Cu to ODS-Cu alloy and summarizes the production route, high heat flux (HHF) test, the pre and post non-destructive examination, and the surface results of the flat-type KW/Cu/ODS-Cu/RAFM mockup after the HHF test. The test results demonstrate that the mockup manufactured according to the fabrication route still have structural and interfacial integrity under cyclic high heat loads.

• Journal of Bio-Environment Control
• /
• v.21 no.3
• /
• pp.220-227
• /
• 2012

This study was conducted to analyze the seeding quality of paprika and the growth and early yield after transplanting of paprika nursed under artificial light and natural light. In this study, blue LED, red LED, and white fluorescent lamps (FL) were used as artificial lighting sources. Photoperiod, average photosynthetic photon flux, air temperature, and relative humidity in a closed transplants production system (CTPS) were maintained at 16/8 h, $204{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 26/$20^{\circ}C$, and 70%, respectively. Leaf length, leaf width, leaf area, top fresh weight and dry weight of paprika seedlings, and chlorophyll content in paprika leaves nursed under LED and fluorescent lamps for 21 days after experiment were significantly affected by light treatments. As compared with the control (white FL), leaf area of paprika grown under blue LED, red LED, and natural light was decreased by 63%, 63%, and 28%, respectively. Top dry weight of paprika grown under blue LED, red LED, and natural light was 64%, 50%, and 22%, respectively, compared with the control. Number of leaves on 18 days after transplanting showed with red LED, blue LED, and natural light by 86%, 84%, and 48%, respectively, compared with the control. On 114 days after transplanting, paprika nursed under blue LED and red LED had relatively short plant height. This result might be caused that the elongation of its internodes was suppressed by the illumination of sole blue or red light. Average number of fruits per plant harvested during 4 weeks after first harvest was 3.5 with red LED, 3.3 with blue LED, 1.0 with natural light, and 2.2 with control, respectively. Early yield of paprika nursed under red LED, blue LED, natural light, and control were 453 g/plant, 403 g/plant, 101 g/plant, and 273 g/plant, respectively. Larger fruit of 136 g was harvested with red LED treatment. Even though the early yield of paprika was greatly increased with artificial lighting, but total yield was almost similar as the harvest period after transplanting in greenhouses was lengthened. From the above results, we could understand that paprika nursed under white FL, blue LED, and red LED showed good growth after transplanting and was early harvested by a week as compared to the natural light. Therefore, the white FL, blue LED, and red LED as the artificial lighting sources in CTPS could be strategically used to enhance the seedling quality, to shorten the harvest time, and to increase the yield of paprika.

• Journal of the Korean Vacuum Society
• /
• v.18 no.4
• /
• pp.318-330
• /
• 2009

A high heat flux test facility using a graphite heating panel was constructed and is presently in operation at Korea Atomic Energy Research Institute, which is called KoHLT-1. Its major purpose is to carry out a thermal cycle test to verify the integrity of a HIP (hot isostatic pressing) bonded Be mockups which were fabricated for developing HIP joining technology to bond different metals, i.e., Be-to-CuCrZr and CuCrZr-to-SS316L, for the ITER (International Thermonuclear Experimental Reactor) first wall. The KoHLT-1 consists of a graphite heating panel, a box-type test chamber with water-cooling jackets, an electrical DC power supply, a water-cooling system, an evacuation system, an He gas system, and some diagnostics, which are equipped in an authorized laboratory with a special ventilation system for the Be treatment. The graphite heater is placed between two mockups, and the gap distance between the heater and the mockup is adjusted to $2{\sim}3\;mm$. We designed and fabricated several graphite heating panels to have various heating areas depending on the tested mockups, and to have the electrical resistances of $0.2{\sim}0.5$ ohms during high temperature operation. The heater is connected to an electrical DC power supply of 100 V/400 A. The heat flux is easily controlled by the pre-programmed control system which consists of a personal computer and a multi function module. The heat fluxes on the two mockups are deduced from the flow rate and the coolant inlet/out temperatures by a calorimetric method. We have carried out the thermal cycle tests of various Be mockups, and the reliability of the KoHLT-1 for long time operation at a high heat flux was verified, and its broad applicability is promising.

• Nuclear Medicine and Molecular Imaging
• /
• v.41 no.1
• /
• pp.42-48
• /
• 2007

Purpose: The purpose of this study is to image metastaic lung melanoma model with optimal pre-conditions for animal handling by using $[^{18}F]FDG$ small animal PET and clinical CT. Materials and Methods: The pre-conditions for lung region tumor imaging were 16-22 h fasting and warming temperature at $30^{\circ}C$. Small animal PET image was obtained at 60 min postinjection of 7.4 MBq $[^{18}F]FDG$ and compared pattern of $[^{18}F]FDG$ uptake and glucose standard uptake value (SUVG) of lung region between Ketamine/Xylazine (Ke/Xy) and Isoflurane (Iso) anesthetized group in normal mice. Metastasis tumor mouse model to lung was established by intravenous injection of B16-F10 cells in C57BL/6 mice. In lung metastasis tumor model, $[^{18}F]FDG$ image was obtained and fused with anatomical clinical CT image. Results: Average blood glucose concentration in normal mice were $128.0{\pm}23.87$ and $86.0{\pm}21.65\;mg/dL$ in Ke/Xy group and Iso group, respectively. Ke/Xy group showed 1.5 fold higher blood glucose concentration than Iso group. Lung to Background ratio (L/B) in SUVG image was $8.6{\pm}0.48$ and $12.1{\pm}0.63$ in Ke/Xy group and Iso group, respectively. In tumor detection in lung region, $[^{18}F]FDG$ image of Iso group was better than that of Ke/Xy group, because of high L/B ratio. Metastatic tumor location in $[^{18}F]FDG$ small animal PET image was confirmed by fusion image using clinical CT. Conclusion: Tumor imaging in small animal lung region with $[^{18}F]FDG$ small animal PET should be considered pre-conditions which fasting, warming and an anesthesia during $[^{18}F]FDG$ uptake. Fused imaging with small animal PET and CT image could be useful for the detection of metastatic tumor in lung region.