• Journal of Power System Engineering
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• v.15 no.3
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• pp.52-57
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• 2011

440A martensitic stainless steels which were modified with reduced carbon content(~0.5wt.%) and addition of small amount of vanadium, tungsten and molybdenum 0.4wt.%, 0.4wt.% and 0.68wt.% respectively were manufactured. Effects of alloying elements and tempering temperatures on the intergranular corrosion were investigated through the method of DL-EPR(Double-electrochemical potentiodynamic reactivation). It was thought that the highest DOS(Degree of sensitization) of specimens was obtained at the tempering temperature of $450^{\circ}C$ regardless of types of alloy because of the precipitation of Cr7C3. Addition of vanadium lowered DOS a little above the tempering temperature of $550^{\circ}C$. It was considered to be effected by precipitation of VC carbides. Intergranular corrosion was influenced more by tempering temperature than by alloying elements of V, W and Mo.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.5
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• pp.226-231
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• 2020

The Cu-Co-Si alloy shows high strength by forming precipitates by aging precipitation heat treatment of supersaturated solid solution treated with solution treatment such as Cu-Ni-Si alloy, and the Co₂Si precipitated phase is dispersed in the copper matrix. The effect of aging treatment on the microstructure, mechanical and electrical properties of Cu-Co-Si alloys for electronic devices was investigated. As a results of SEM/EDS analysis, it was found that Co₂Si precipitates of 30~300 nm size were distributed in grains. By performing the double aging treatment, it was possible to improve the strength and electrical conductivity by dispersing the fine precipitate evenly.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.335-339
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• 2001

The Tropical Rainfall Measuring Mission(TRMM) Satellite was launched in November 1997, carrying into orbit the first space-borne Precipitation Radar(PR). The purpose of this study is to identify the relationship between TRMM/PR and AWS raingage data, and test the possibility to apply storm runoff prediction. Four TRMM/PR data in 1999 for Yongdam watershed was adopted and made a simple linear regression equation using AWS data. By using the equation, the storm runoff was estimated with the adjusted rainfall. TRMM/PR rainfall and runoff was overall underestimated by the carry-over effect of rainfall error and SCS-CN value selection.

• Korean Journal of Microbiology
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• v.19 no.3
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• pp.121-127
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• 1981

The constituents of molasses and effect of pH precipitate formation in molasses solution, vary according to its producing districts. The formation of precipitation is not so changeable in the range of buffering zone of molasses solution(pH4.3-6.3) in philippine molasses according to the change of pH value. On lower or higher than the range of buffering zone, the precipitation is increased from pH 4.3 to 2.8 and from 6.3 to 8.1, it is decreased when pH value is lower or higher than the pH value range. For molasses clarifying, it had better adjust the pH of molasses solution to neutral or weak alkali range out of the alkai side of the buffering zone, with lime solution. And then, add the calcium super phosphate solution to pH value of alkali side in buffering zone, as much as the pH of clarified molasses solution can reach to middle value in buffering zone. For the equilibrium of pH value on clarifying molasses, it takes plenty of time more than 6 hours.

• Korean Journal of Crystallography
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• v.15 no.1
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• pp.44-50
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• 2004

Spinel structured lithium managanese oxide $(LiMn_2O_4)$ powder with well defined facetted morphology was prepared by precipitation-evaporation method. {111}, {110}, and {100} planes are mainly observed in the $LiMn_2O_4$ powder. And powder shape of tetradecahedron and octahedron was observed depending on the calcinations temperature. The observed powder morphology observed seemed to be related to the nonstoichiometry of the oxygen in the $LiMn_2O_4$ spinel structure. Oxygen nonstoichiometry might be responsible for the Jahn-teller effect and structure transition which in turn affects the surface energy of the {111}, {110}, and {100} planes. Powder shape transition from tetradecahedron to octahedron seemed to be related to the surface energy of the {111}, {110}, and {100} planes with oxygen nonstoichiometry.

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.172-177
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• 2012

Mo-doped $LiFePO_4$ was synthesized via co-precipitation method using sucrose as the carbon source. Structure, surface morphology, and the electrochemical properties of the synthesized olivine compounds were investigated using Rietveld refinement of X-ray diffraction data (XRD), scanning electron microscopy (SEM), and electrochemical charge-ischarge tests. Spherical morphology with the particle size of ${\sim}8{\mu}m$ authenticated the enhanced tap density and volumetric energy density of the synthesized materials. Charge-discharge behavior of $LiFePO_4$ and Mo-doped $LiFePO_4$ cells demonstrated a specific capacity of 130 and 145 mAh $g^{-1}$, respectively. Mo-doped $LiFePO_4$ cells exhibited an excellent discharge capacity at 96 mAh $g^{-1}$ at 7 C-rate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.237-241
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• 2000

The effects of Si addition on the precipitation processes of in Al-Cu-Si alloy films were studied by the transmission electron microscopy. Deposition of an Al-1.5Cu-1.5Si (wt. %) film at $305^{\circ}C$ resulted in formation of fine, uniformly distributed spherical $\theta$-phase particles due to the precipitation of the $\theta$ and Si phase particles during deposition. For deposition at $435^{\circ}C$, fine $\theta$-phase particles precipitated during wafer cooldown, while coarse Si nodules formed at the sublayer interface during deposition. The film susceptibility to corrosion is discussed in relation to the film microstructure and deposition temperature.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.89-96
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• 2004

Hydroxyapatite powder were synthesized by precipitation method, varying pH, and reaction temperature. The powders were heated at 1,200$^{\circ}{\cdots}$ and 1,300$^{\circ}{\cdots}$ for fabrication of dental prosthesis. The results are as follows: Synthesized powder showed the smallest particle in size, under the conditions of pH 11 and reaction temperature 37$^{\circ}{\cdots}$. The hydroxyapatite was partially converted to $\alpha,\;\beta$-TCP at 1,200$^{\circ}{\cdots}$ and 1,300$^{\circ}{\cdots}$. Mechanical strength of sample was affected by such powder preparation conditions as pH and reaction temperature and sintering temperature. The mechanical strength of sample prepared under the same conditions was increased with increasing pH, reaction temperature and sintering temperature.

• Journal of Korean Society of Forest Science
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• v.99 no.2
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• pp.197-203
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• 2010

The data of average temperature, average relative humidity, precipitation and average wind speed were collected from 674 meteorological stations in China. A specific procedure that processes original data into a new data format needed in forest fire danger rating forecast system of China was introduced systematically, and the feasibility of this method was validated in this paper. In addition, a set of meteorological data processing software was constructed by the secondary development of GIS in order to realize automation of processing data for the system. Results showed that the approach preformed well in handling temperature, average relative humidity and average wind speed, and the processing effect of precipitation was acceptable. Moreover, the automated procedure could be achieved by GIS and the working efficiency was about 3 times as much as that of manual handling. The informationization level of processing meteorological data was greatly enhanced.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.2
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• pp.91-102
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• 1996

Microstructural control to produce multiphase structure has received much attention to improve the high temperature strength as well as low temperature ductility of intermetallics. Transmission electron microscopic investigation has been carried out concerning the effect of Cr-precipitation on the mechanical properties of B2-ordered NiAl containing 4 to 8 mol% of Cr. By aging at temperatures around 973 K after solution annealing, fine spherical precipitates took place homogeneously in the NiAl matrix and the alloys hardened appreciably. Selected area electron diffraction (SAED) patterns have not revealed any additional extra-spots during aging, because the Cr-particles show cube-cube orientation relationship and keep a perfect coherency with the ordered matrix lattice. Dislocations were confirmed to bypass the particles during deformation. Although the dispersion of Cr-particles increased the yield strength of NiAl at intermediate temperature, the strength decreased appreciably at higher temperatures.