• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.703-714
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• 1994

Sintering and microstructure of Ce-TZP/Al2O3 composite with $\alpha$-Al2O3 matrix containing dispersed 5~50 vol% ZrO2 were discussed. Sintered density was increased with elevating forming pressure in range of 6~300 MPa and about >99.2% of theoretical density was obtained at 1$600^{\circ}C$ for 2h in case of 300 MPa of 6~300 MPa uniaxially cold-pressed compacts containing 20 vol% ZrO2. All kinds of different batch composition exhibited nearly the same shrinkage behaviour with end-point shrinkage between 20 and 24%, and had the maximum shrinkage rate (0.41~0.54%/min) around 140$0^{\circ}C$. Grain growth was occurred faster in $\alpha$-Al2O3 than in {{{{ gamma }}-Al2O3 starting matrix during sintering at 1$600^{\circ}C$. Bimodal pore size distribution of interaglomerate pores with size of 0.03~0.2 ${\mu}{\textrm}{m}$ and of interaglomerate pores with size of around 60 ${\mu}{\textrm}{m}$ was obtained in Ce-TZP/$\alpha$-Al2O3 composite sintered at 130$0^{\circ}C$. But unimodal pore size distribution with around 0.1 ${\mu}{\textrm}{m}$ was observed in Ce-TZP/{{{{ gamma }}-Al2O3 composite sintered at the same temperature. Microcracks were occurred due to the tlongrightarrowm transformation of ZrO2 on cooling process.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.6
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• pp.328-334
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• 2000

A lithium ion secondary battery using carbon as a negative electrode has been developed. Further improvements to increase the cell capacity are expected by modifying the structure of the carbonaceous material. There are hopes for the development of large capacity lithium ion secondary batteries with long cycle, high energy density, high power density, and high energy efficiency. In the present paper, needle cokes from petroleum were examined as an anode of lithium ion secondary battery. Petroleum cokes, MCL(Molten Caustic Leaching) treated in Korea Institute Energy Research, were carbonized at various temperatures of 0, 500, 700, $19700^{\circ}C$ at heating rate of $2^{\circ}C$/min for lh. The electrolyte was used lM liPF6 EC/DEC (1:1). The voltage range of charge & discharge was 0.0V(0.05V) ~ 2.0V. The treated petroleum coke at $700^{\circ}C$ had an initial capacity over 560mAh.g which beyond the theoretical maximum capacity, 372mAh/g for LiC6. This phenomena suggests that carbon materials with disordered structure had higher cell capacity than that the graphitic carbon materials.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.533-534
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• 2006

1mm-thick BLT ceramics were sintered in accordance with a bulk ceramic fabrication process. All XRD peaks detected in the sintered ceramics were indexed as the Bi-layered perovskite structure without secondary phases. Density was increased with increasing the sintering temperature up to $1050\;^{\circ}C$ and the maximum value was about 98% of the theoretical density. The remanent polarization (2Pr) value of BLT ceramic sintered at $1050\;^{\circ}C$ was approximately $6.5\;{\mu}C/cm^2$ at the applied voltage of 4.5kV. From these results, a BLT ceramic target for plused laser deposition (PLD) system was successfully fabricated.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.281-283
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• 1994

The impedance characteristics of planar ICP have been measured and compared with the theoretical results obtained by the field equation. The resistance of the total impedance had a maximum point and the inductance decreased monotonically as the electron density increased from $2.5{\times}10^{10}cm^{-3}$ to $7{\times}10^{11}cm^{-3}$ and the Pressure from 1mT to 50mT. The impedance characteristics were also dependent on the profile of the electron density. The effective collision frequency, ${\nu}_{eff}$ was $9.0{\times}10^6Hz$ at 5mT and $.5{\times}10^7Hz$ at 100mT. The effective collision frequency at 5mT was not so different from that at 100mT and it is doe to the reduction of the discharge channel cross-section at high pressure. The estimated effective collision frequency from the simulation data was of the same order as the measured one.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.276-277
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• 2006

1mm-thick BLT ceramics were sintered in accordance with a bulk ceramic fabrication process. AII XRD peaks detected in the sintered ceramics were indexed as the Bi-layered perovskite structure without secondary phases. Density was increased with increasing the sintering temperature up to $1050^{\circ}C$ and the maximum value was about 98% of the theoretical density. The remanent polarization (2Pr) value of BLT ceramic sintered at $1050^{\circ}C$ was approximately $6.5\;{\mu}C/cm^2$ at the applied voltage of 4.5 kV. The calculated electromechanical coupling factor ($k_t$) of it was about 5% and the mechanical quality factor (Qm) was about 2200. From these results, a BLT ceramic target for pulsed laser deposition (PLD) system was successfully fabricated.

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.182-187
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• 2007

10 mol% $Gd_{2}O_{3}-CeO_{2}$ powder was sintered by microwave in a 2.45 GHz multimode cavity to develop a dense electrolyte layer for intermediate temperature solid oxide fuel cells (IT-SOFCs). Samples were sintered from $1100^{\circ}C$ upto $1500^{\circ}C$ by $50^{\circ}C$ difference and kept for 10 min and 30 min at the maximum temperature respectively. Theoretical density of the sample sintered at $1200^{\circ}C$ for 10 min was 95.4% and increased gradually upto 99% in the sample sintered at $1500^{\circ}C$ for 30 min. All of sintered samples showed very fine microstructures and the maximum average grain size of the sintered sample at $1500^{\circ}C$ for 30 min was $(0.87{\pm}0.42){\mu}m$. Ionic conductvity of the samples were measured by DC 4 probe method.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.119-126
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• 1999

The rolling fatigue lives (RFL) of five kinds of silicon nitride balls were investigated. Four kinds of Si$_3$N$_4$ balls were fabricated using different raw materials, sintering aids and sintering conditions, Commercially available Si3N4 ball was also studied for comparison. All the balls were finished up to the dimensional accuracy of Grade 10 defined in KS B 2001 (Steel Balls for Ball Bearings) with a size of 9.525mm. RFL tests were then conducted under the initial theoretical maximum contact stress 6.38 GPa and the spindle speed 10,000 rpm. Gear oil was provided by oiled race as lubricant. The results of RFL test indicated the prerequisitic conditions for the long rolling life of Si$_3$N$_4$ball : (1) the high density, (2) mjcrostructures consisted of small uniformly distributed grains, (3) little glassy phase in grainboundary, and (4) little crystalline phase and secondary phase that induces residual thermal stress due to the differences of thermal expansion coefficient with Si$_3$N$_4$Phase.

• Korean Journal of Materials Research
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• v.9 no.1
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• pp.51-56
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• 1999

The $BaTiO_3$ powders were synthesized by GNP (Glycine-Nitrate process). The powders were prepared using carbonate and alkoxide as starting materials and nitric acid was used as a solvent for starting materials as well as an oxidant for combustion. the effects of aggregates in $BaTiO_3$ powders on green densities, sintering and dielectric characteristics were investigated. When the glycine/cation molar ratio was 1.2, reactivity of self-combustion was most intensive and the degree of aggregates after calcination was low. On sintering at $1400^{\circ}C$, maximum theoretical relative density(94.99%%0 was obtained in case of 1.2 molar ratio of glycine/cation. The dielectric constant of this sintered $BaTiO_3$ was 1919.

• Journal of the Korean Institute of Navigation
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• v.21 no.2
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• pp.19-40
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• 1997

When designing new marine traffic routes, it is desirable that the congestion due to traffic volume is evaluated by theoretical traffic capacity or by traffic simulation. Most of these techniques are applied to single server which is not considered channel width. Over-taking or paralle sailing of two or more vessels is allowalbe in Dover, Uraga, Gaduk-sudo, etc under their traffic capacity. In this paper, the Bumper Model is introduced to multiple severs in narrow channel and applied to Uraga Channel in Japan. The minimum width of Uraga Channel is 1, 400 m and its design traffic capacity is evaluated 19.26 ~ 19.52% of the basic traffic capacity. The traffic capacity on Gaduk Channel according to Busan New Port Development in 2011 will be estimated 3.59 % of maximum density and equal to 18.6% of that on Uraga Channel in 1992. The channel width Gaduk-sudo is designed 1, 600~2, 460 m and evaluated safe enough.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.1
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• pp.91-101
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• 1986

Relations of each factor affected by emissions and the prediction of performance have been analyzed numerically by cycle simulation in the Spark Ignition Engine. Through theoretical analysis and experiments, the results are obtained as below. The calculated results and the experimental ones are almost highly agreeable on cycle simulation model, exhaust gas analysis and efficiency for processes in cylinder. Therefore this model is proved appropriate and can be useful for optimum design of Spark Ignition Engines on parametric studies. It is reaffirmed that the Wiebe's function is suitable for predicting Combustion Ration in Spark Ignition Engines. On parametric studies, it is found that optimum conditions whose density of emissions are lower and efficiency is maximum within propriety value are crankangle ATDC $15^\circ-20^\circ$, 2400 rpm. A/F=16 in this experiment.