• Proceedings of the Korea Association of Crystal Growth Conference
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• 2000.06a
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• pp.179-193
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• 2000

Aluminium titanate (Al₂TiO5) with an excellent thermal shock resistant and a low the expansion coefficient was obtained by solid solution with MgO, SiO₂, and ZrO₂ in the Al₂TiO5 lattice or in the grain boundary solution through electrofusion in an arc furnace. However, these materials have low mechanical strength due to the presence of microcracks developed by a large difference in thermal expansion coefficients along crystallographic axes. Pure Al₂TiO5 tends to decompose into α-Al₂O₃ and TiO₂-rutile in the temperature range of 750-1300℃ that rendered it apparently useless for industrial applications. Several thermal shock tests were performed: Long therm thermal annealing test at 1100℃ for 100h; and water quenching from 950 to room temperature (RT). Cyclic thermal expansion coefficients up to 1500℃ before and after decomposition tests was also measured using a dilatometer, changes in the microstructure, thermal expansion coefficients, Young's modulus and strengths were determined. The role of microcracks in relation to thermal shock resistance and thermal expansion coefficient is discussed.

• Journal of Welding and Joining
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• v.26 no.1
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• pp.76-82
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• 2008

The effect of Nb addition on the precipitation and precipitate coarsening behavior was investigated in Ti and Ti + Nb steel weld HAZ. A dilatometer equipped with a He-quenching system was used to simulate the weld thermal cycle. Compared to $TiC_yN_{1-y}$ precipitate in a Ti containing steel, $Ti_xNb_{1-x}C_yN_{1-y}$ complex particle with addition of Nb is precipitated in a Ti + Nb containing steel. Meanwhile, precipitate coarsening occurred more easily in Ti + Nb steel, which may be because the high temperature stability of $Ti_xNb_{1-x}C_yN_{1-y}$ complex particle is deteriorated by the Nb addition.

• Journal of the Korean Ceramic Society
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• v.22 no.6
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• pp.9-14
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• 1985

When the barium titanate is Synthesized in Solid-solid reaction the abnormal expansion occurs at about 110$0^{\circ}C$. The mixture was made of corresponding to the theoretical composition of barium titanate. The mixture was fired at various temperature from 90$0^{\circ}C$ to 130$0^{\circ}C$, After that the specimen was tested closely with XDR dilatometer and SEM. The results indicate that 1, The activation energy of barium titanate formation was 42 Kcal/mole. 2, Thermal expansion up to to 90$0^{\circ}C$ was mainly caused by $CO_2$ whereas it was mainly caused by the formation of the secondary phase above 100$0^{\circ}C$. 3. Thermal expansion was not influenced by the forming pressure up to 1000kg/$cm^2$ but it was largely influenced bythe forming pressure above 200kg/$cm^2$.

• Journal of the Korean Ceramic Society
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• v.28 no.10
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• pp.824-830
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• 1991

$\alpha$-SiC(B; 0.4 wt, C; 3 wt%) was sintered in Ar atmosphere from 205$0^{\circ}C$ to 220$0^{\circ}C$ by means of pressureless sintering and gas pressure sintering in order to find optimum sintering condition of $\alpha$-SiC. Mechanical properties and microstructures of sintered bodies were investigated according to sintering method. The effect of sintering condition on sinterability of $\alpha$-SiC was also examined by using the dilatometer. 97.5% and 98.8% of theoretical density were obtained from pressureless sintering and gas pressure sintering of $\alpha$-SiC powder, respectively. And modulus of rupture was measured as 270~350 MPa and 420 MPa respectively.

• Journal of the Korean Applied Science and Technology
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• v.13 no.3
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• pp.119-125
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• 1996

The excess volumes of mixing of benzyl alcohol, ethyl alcohol, halothane, and procaine in vesicle and suspensions of several lipids have been determined at $25^{\circ}C$ using a excess volume dilatometer. The potency of general anesthetics has long been known to be correlated with lipid solubility. Denaturations of the bacteriorhodopsin, which is a sole membrane protein in the purple membrane of Halobacteriun Halobium, were studied by UV/Vis absorption changes. The excess volumes of mixing of benzyl alcohol and procaine in egg lecithin were all found to be negative and this result was confirmed as Miller's supposition.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.619-627
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• 2008

In this study, through dissipation test of DMT predicted Horizontal Coefficient of Consolidation at marine clay. CPTu Dissipation test, laboratory consolidation test compared with $C_v$, through it examined application. The result, DMT calculated horizontal coefficient of consolidation by $P_2$-Log(t) method of DMT-A method and C-$\surd$t(min) method. This horizontal coefficient of consolidation calculated larger than $P_2$-Log(t) method. $P_2$-Log(t) method of DMT, Torstensson of CPTu and Houlsby & Teh(1991) appeared similar to tend. This approximate value is possible application in marine clay. It'll need to study continuously through collection of data.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.979-986
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• 2008

In this study, it enforced DMT test, CPTu test, laboratory consolidation test, because it estimated stress history of Gwangyang port marine clay. Through DMT test obtained Horizontal stress index($K_D$), predicted overconsolidation ratio by $K_D$. To compare empirical equation with laboratory consolidation test and CPTu test calculated OCR examined application. The result, Powell & Uglow(1988) method underestimated OCR value in comparison with Suggestion. Comparatively Byeon wi yong(2004) and Chang(1991) method seem to exactly predict in-situ stress states. Sugawara(1988) method of CPTu test seems to underestimate OCR.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1374-1377
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• 2003

Ti-8Ta-3Nb is made for biomaterial. The experimental speciments are as-cast Ti-8Ta-3Nb and Ti-8Ta-3Nb swaged. The solution treatment in the range 760-96$0^{\circ}C$have been carried out. The microstructural investigations have been carried out on the specimens after the solution treatment. and the hardness have been measured. And the specific heat and the dilatometer of Ti-8Ta-3Nb swaged have been measured. From the result, the $\beta$ transus of the alloy was determined to be 880-86$0^{\circ}C$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.196-201
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• 2000

A thermodynamic model was developed to analyze the characteristics of the heat generation during transformation of austenite in 0.186wt% and 0.458 wt%. carbon steels. The heat capacity and the heat evolved during transformation were formulated as functions of temperature and chemical composition for ferrite bainite and pearlite. in addition using the transformation dilatometer the transformation heat evolved during cooling was measured and the transformation behavior was observed. It was found that the heat capacity of ferrite was similar to those of pearlite and bainite. The heat capacity of ferrite was greater than that of bainite which was greater than that of pearlite. The molar heat of transformation to pearlite was greater than that to bainite which was greater than that to ferrite. The heats were found to be increased with decreased temperature and increasing the carbon content, It was also observed that the thermodynamic model. The heat of transformation in the higher carbon steel was greater than that in the lower carbon one. This was attributed to the lower transformation temperature and the greater amount of transformed pearlite in the higher carbon steel.

• Journal of Powder Materials
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• v.1 no.1
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• pp.52-59
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• 1994

Since the coefficient of thermal expansion (CTE) of matrix phase is larger about 4 times than that of W particle in tungsten heavy alloy, the thermal stresses due to the CTE difference between the two phases are induced in the alloy during heating and cooling processes. In the present study, a series of W heavy alloy containing various W particle volumes of 0 to 90% is made to investigate the residual stress taking place during cooling process. The CTE and residual stress of the series of alloy are measured by dilatometer and X-ray diffractometer. The residual stress of W particle is in compressive stress irrespective of W particle vol% and tends to increase with decreasing W particle vol% while that of the matrix phase is in tensile stress. The measured residual stress of W particle is about a third of calculated thermal stress. The influence of W particle vol% on the residual stress of W heavy alloy is discussed in terms of the deformation behaviors of W particle and matrix phase.