• Proceedings of the KSR Conference
• /
• 2003.10c
• /
• pp.210-215
• /
• 2003

At present, communication network for subway is making use of the train radio system for main network and normally established a base station every three subway station. It is talk over the telephone between a locomotive and the traffic control for careful train service. Besides, mobile telephone equipment is using for service improve and convenience to passengers such as 011, 016, 017, 019 and what not. However, the train radio system has been occurring a various problems when a state of emergency because it is able to compose only one communication route each base station zone. We could have improving like this problems through induce the TRS(Trunked Radio System), though because have been able to compose multilateral communication route in case of linking with LCX(Leaked Coaxial) cable which is established. Therefore, we could be able to a fitting meet the emergency as train firing etc.. and efficient use of limited frequency resources.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.232-235
• /
• 1999

In this paper, We described the effect of $MoO_3$ Addition and firing temperature on the microwave dielectric properties of $BiNb0_4$ ceramics. The specimens prepared by conventional mixed method was addicted by 0 - 0.03 wt% $MoO_3$ and fired at 860 - $950^{\circ}$ for 3hr. Density increased when $MoO_3$ is below O.Olwt% but decreased when over O.Olwt%. $BiNb0_4$ ceramics addicted with CuO 0.03wt % and $MoO_3$ 0.01 wt% showed microwave dielectric properties, Dielectric constant 37.5, Quality factor[Qx$f_0$]5500, Temperature coefficient of resonance frequency 15ppm/$^{\circ}$

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.157-161
• /
• 2000

Blue phosphor of Ba-Mg-Al-O:Eu$^{2+}$ phase was fabricated by conventional firing techniques under reducing atmosphere and its photoluminescence properties are studied with varying Eu concentration and phost-annealing temperature under air atmosphere. This phosphors were well crystallized with particle size in the range of 3~5um and emitted a blue light at a dominent wavelength 450nm for 254nm UV irradiation. The concentration quenching wit Eu$^{2+}$ was that with increasing Eu concentration the energy transfer between the activator ions steadily improves, so that the excitation energy is transported over larger distances through the lattice before luminescence can occur. Thermal quenching also occurred in this phosphor means that in a host lattice with the $\beta$-alumina structure the bond of an Eu$^{2+}$ ion with the nearest-neighbour oxygen ion is much stronger than in a lattice with the magnetoplumbite structure.cture.

• Progress in Superconductivity and Cryogenics
• /
• v.9 no.2
• /
• pp.19-22
• /
• 2007

We report the phase and microstructure evolutions of metal trifluoroacetate (TFA) precursor films in the TFA-MOD process of YBCO films on the LAO (100) substrates. It was confirmed that the precursor films were decomposed into $Y_2O_3$, $BaF_2$, and CuO nanoparticles after the initial heat treatment up to 400$^{\circ}C$. After a subsequent heat treatment at higher temperatures ranging from 700 to 850$^{\circ}C$ for 2 h, these nano-sized phases are converted into YBCO films. High Jc(77K, sf)-YBCO thin films (over 2 MA/$cm^2$) were successfully fabricated with firing temperatures ranging from 775 to 850$^{\circ}C$ for 2 h, where films were composed of dense microstructures with large grains.

• Journal of the Korean Ceramic Society
• /
• v.21 no.4
• /
• pp.366-372
• /
• 1984

Unstabilized Zirconia was added to basic composition under 44$mu extrm{m}$ of 57.80wt% Clay-22.20wt% Chamotte-20.00wt% Agalmatolite system. Here the amount and the particle size of Zirconia were 5-25wt% and -20${\mu}{\textrm}{m}$ respectively and the body of these composition was first at 135$0^{\circ}C$. The results obtained from examining the properties of sintered body were as follows. 1. Firing linear shrinkage apparent density and bulk density apparent porosity and water absorption of the samples had the tend to increase according as the particle size of zirconia became larger and the amount of zirconia increased. 2. Modulus of rupture was inversely proportional to the particle size and the additive amount of zirconia, . Especially in case that the particle size of zirconia over 5${\mu}{\textrm}{m}$ and the additive amount of zirconia was 25wt% the modulus of rupture had shrunk drastically. 3. The maximum value of KIC was obtained at 20wt% additive amount of zirconia according to the each particle size of zirconia. Especially the highest value of KIC is 2, 173 M. Pa. M1/2 when the particle size of zirconia is 5~10${\mu}{\textrm}{m}$ and the additive amount is 20wt%.

• Journal of the Korean Ceramic Society
• /
• v.44 no.3 s.298
• /
• pp.157-161
• /
• 2007

Line width under $100\;{\mu}m$ with good resolution is difficult to achieve using conventional thick-film process utilizing screen printing method. However combined with lithography technology finer line and space for miniaturization and highly integrated package is achievable. In this study, photosensitive Ag paste of optimum formulation used for thick film lithography technology was fabricated by various Ag powder, glass powder and additives. As the result, line width of $30\;{\mu}m$ with good definition and reduced mismatch during co-firing with LTCC substrate was acquired. Formulated Ag paste was used to pattern embedded fine line inductor with over 90% yield.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.1
• /
• pp.31-39
• /
• 2014

The performance of fuel cell/gas turbine hybrid systems is highly affected by system configuration. In this study, the performance of a hybrid system combining a molten carbonate fuel cell (MCFC) and an indirectly fired gas turbine was predicted. Firstly, general performance trends of the hybrid system depending on major design parameters were examined. Then, the most feasible design options with the least impact on the MCFC stack design conditions were drawn. The economic advantage of the hybrid system over the basic MCFC only system was evaluated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.698-701
• /
• 2011

Over recent several years, researches for the less sensitive gun propellant development have been carried out with promising the product of propellants which have temperature independent characteristics using the new energetic plasticizing mixture as Di-nitro-diaza-alkanes. During this study, the promising propellant formulation having temperature ballistic properties as well as better behaviors concerning the cold brittleness of the materials was confirmed by results in tests of a closed bomb and 40mm Gun firing. On-going research on the optimized shape, formulation and processes of the propellant is progressing. From now on it should be done present study to establish the better composition and processes.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.1088-1090
• /
• 2001

In general, Power SCR(Silicon Controlled Rectifier) is most widely used in Power Plant as well as Industrial field. It has been controlled and operated according to its own control method. Especially, in case of Power plant, it plays a major role in AVR(Automatic Voltage Regulator) or electro chlorination control circuits. Generally, they used in Analog control system at above field. But each SCR current value is different because of load unbalance or switching characteristic variations, it may cause power plant unit trip or system disorder according to SCR element burn out or bad operating condition. Therefore, in this paper a development of 3 phase current balance control unit is described, it gets over the past analog control system limit, uses DSP(Digital signal processor) had high speed response, controls SCR gate firing angle for 3 phase current balance.

• Journal of Environmental Science International
• /
• v.19 no.2
• /
• pp.255-260
• /
• 2010

A stabilization/solidification (S/S) process for lead (Pb) contaminated soils was evaluated using waste cow bone containing apatite like compounds. Soil samples obtained form firing range were treated with waste cow bone. The effectiveness of stabilization was evaluated based on the Korean Standard Leaching Test (KSLT) and soil pH. The leached concentration reduced with increased in dose of waste cow bone. Overall, the KSLT results showed that Pb concentration in soils are significantly affected by amount of waste cow bone. When soil amended with 20 % of waste cow bone, less than 0.1 mg/kg was leached, and soil pH was increased from 6.5 to 8.4. Same results were obtained when finer waste cow bone was applied. The reachable concentration of Pb in soil showed in inversely proportional to solid/liquid ratio. Aging periods indicate improving mix design was applied. Relatively high lead concentrations was observed at the first 1 days, however leaching profile are reduced significantly over time for all mix designs.