• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.2
• /
• pp.97-103
• /
• 2014

Phase transition properties of the copolymer films of polyvinylidene fluoride (PVDF) and trifluoroethylene(TrFE), P(VDF-TrFE), were studied with X-ray diffraction (XRD) and polarization modulated ellipsometry (PME). XRD studies on both Langmuir-Blodgett (LB) films and spin coated films exhibit conversions from ferroelectric phase to paraelectric phase at $108{\pm}2^{\circ}C$ on heating and paraelectric phase to ferroelectric phase at $78{\pm}2^{\circ}C$ on cooling. The presence of the ferroelectric-paraelectric phase transition is also confirmed by the PME technique for the first time in this study. PME was proved to be a very sensitive tool in the measurement of the structural changes at the nano-thickness films.

• Journal of IKEEE
• /
• v.14 no.2
• /
• pp.64-68
• /
• 2010

This paper proposes efficient log and exponent calculation methods using a dual phase instruction set without additional ALU unit for a mobile enviroment. Using the Dual Phase Instruction set, it extracts exponent and mantissa from expression of floating point and calculates 24bit single precision floating point of log approximation using the Taylor series expansion algorithm. And with dual phase instruction set, it reduces instruction excution cycles. The proposed Dual Phase architecture reduces the performance degradation and maintain smaller size.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2003.11a
• /
• pp.135-138
• /
• 2003

Based on solid phase extraction, gas chromatography and mass spectrometry procedure for determining phenol and its derivatives in natural water was presented. In solid phase extraction, three types of techniques using solid phase adsorption material were treated with acid and salt, and converted second portion of acetyl derivatives. Under the these condition, extraction efficiency and detection ability dependent on extraction methods were discussed. Obtained results using optimized solid phase extraction techniques showed more convenience, simplifier and lower cost than the conventional analytical methods with holding wide dynamic range and lower detection limits.

• Bulletin of the Korean Chemical Society
• /
• v.6 no.3
• /
• pp.132-135
• /
• 1985

Four types of the phase diagrams indicating the partial miscibilities in polymer-polymer or polymer-solvent systems have been explained in terms of the extended Flory-Huggins lattice theory. In this article, the term $kT_{\chi}$ in the theory is expressed as a function of temperature. Using such $a_{\chi}$-parameter, the simplest forms of geometrical conditions are derived for each type of the four partial miscibilities in polymer systems. The calculated partial miscibilities are in good agreement with the experiment.

• Korean Membrane Journal
• /
• v.9 no.1
• /
• pp.27-33
• /
• 2007

PVDF membrane formation via TIPS was performed for PVDF/DBP and PVDF/DMP systems. PVDF/DBP system showed solid-liquid phase separation behavior, while PVDF/DMP system has liquid-liquid phase separation characteristic as well as solid-liquid phase separation characteristic. PVDF contents and cooling conditions had great influence on structure, and the effects of each parameter were examined. Spherulitic structure was obtained due to the dominant PVDF crystallization. Diluent rejected to the outside of spherulite occupied the surface of the PVDF spherulites to result in the microporous spherulite formation and micro-void between spherulites. PVDF/DMP system had competitive solid-liquid and liquid-liquid phase separation depending on the cooling path.

• Journal of architectural history
• /
• v.31 no.3
• /
• pp.7-16
• /
• 2022

Fen(分°) is the proportional dimension unit of the standard timber section on Yingzaofashi(營造法式), and there is a phrase that not only structural members but the whole structural design of a building also use Fen as the dimension unit on the book. But in fact only the section dimensions of structural members are recorded by Fen, but the design dimensions are recorded by Chi(尺) on the book. Other historical records also described the building size by Chi. So there has been long-standing debate on the phase in Chinese architectural history society, including the recent confrontation on the analysis of survey figures of the east great hall of Foguangsi temple(佛光寺 東大殿). This paper analyzes all the records about the size of structural members and section planning on the book to make various calculation and evaluation. And it makes a survey of Cai(材) as the dimension and design unit between Chi and Fen through geometric analysis. Cai might be a rough unit of measurement in terms of structural and proportional scheming on Yingzaofashi, and the full size Cai(足材) had been a building scheming module before the Song dynasty.

• Journal of the Korean Chemical Society
• /
• v.32 no.2
• /
• pp.135-143
• /
• 1988

The correlations between chromatographic parameters of monosubstituted benzenes and several physical parameters in reversed phase liquid chromatography were studied. The relationships between retention data and polarity index were investigated by plotting $log(log k'_S/k'_B)$ vs. $P'_S/P'_B$ which were relative retention and relative polarity index of monosubstituted benzenes with respect to benzene, respectively. The linear relationship between relative retention and polarity index was observed for the monosubstituted benzenes having polar group, while in case of those having nonpolar group, the good linearity was observed by combination with relative molecular weight i.e. $(P'_S/P'_B)/(MW_S/MW_B)$. Multivariant regression analysis, $a(P'_S/P'_B)+b(MW_S/MW_B)$+c did not give significantly better correlations compared to single variant analysis, $a[(P'_S/P'_B)/(MW_S/MW_B)]$+c, but multiple stepwise regression analysis was recommended when several physical parameters simultaneously were chosen. The best correlation between retention data for monosubstituted benzenes taken from the literature and substituent constant(${\pi}$), derived from hydrophobic parameter and the first order molecular connectivity index$(^1{\chi}^{\nu})$, was established for methanol/water mobile phase system. The larger the surface coverage of the stationary phase, the higher was the correlation coefficient between these two parameters and retention data.

• Corrosion Science and Technology
• /
• v.5 no.6
• /
• pp.189-195
• /
• 2006

Effects of tungsten (W) on the precipitation kinetics of secondary phases and the associated resistance to pitting corrosion of 25%Cr duplex stainless steels were investigated through microstructural and electrochemical noise analyses. With the partial substitution of W for Mo in duplex stainless steel, the potential and current noises of the alloy were significantly decreased in chloride solution due to retardation of the ${\sigma}$ phase precipitation. The preferential precipitation of the $\chi$ phase in the W-containing alloy during the early period of aging contributed to retarding the precipitation of the $\sigma$ phase by depleting W and Mo along grain boundaries. In addition, the retardation of the nucleation and growth of the $\sigma$ phase in the W-containing alloy appears to be attributed to the inherently low diffusivity of W compared with that of Mo.

• Journal of Korea Foundry Society
• /
• v.35 no.2
• /
• pp.23-28
• /
• 2015

This work presents the effect of the cooling rate on the precipitation of super duplex stainless steel. Specimens of super duplex stainless steel with a specific composition were cooled at various cooling rates after being melted at $1550^{\circ}C$ in a directional solidification furnace. Ferrite (${\delta}$), Austenite (${\gamma}$), Sigma (${\sigma}$), and Chi (${\chi}$) phases were precipitated when the cooling rate was lower than 0.22 K/s. When the cooling rate was 0.22 K/s or faster, ${\sigma}$ and ${\chi}$ phases were not precipitated.

• International conference on construction engineering and project management
• /
• 2015.10a
• /
• pp.70-71
• /
• 2015

Cost management always being the matters for project manager as well as other entities involved the construction projects. Vietnam is emerging country, many construction works were carried out and lot of construction projects will be developed in the near future with a huge investment capital come from outside and inside Vietnam. In recent years, international project management firms enter the Vietnam construction market, some issues emerged need to be solved. In which cost and schedule of the construction project was put in a thoroughly consider of not only project management team but also stakeholders. The research attempts to identify and assess the relationship of factors affecting the construction cost in construction phase in Ho Chi Minh City, Vietnam. Five main factor groups Owners/clients; Consultants; Contractors; Resource and Other were identified to propose the solution for cost management.