• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.925-934
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• 1994

Nickel recovered from the spent oil-hydrogenation catalysts was used in hydrogenation catalyst preparation. The spent catalyst contains approximately 21.8% Ni, 0.7% Mg, and small quantities of Al, Fe, and Zn. Nickel recovery was obtained by inorganic acid digestion in the order of HCI>$NHO_3$>$H_2SO_4$. For $HNO_3$, 3hour extraction with 3N solution was satisfactory. In the PH range of 6.5~9.0, Ni recovery was higher, but metallic impurities were found to be coprecipitated. The PH in the range of 7.0~9.0 seems to be the optimum condition for separation to obtain acceptable Ni precipitates without the decrease of purity. The catalysts prepared with reclaimed nickel by wet reduction methods showed catalytic activities close to those prepared using reagent nickel in the oil hydrogenation reaction. The surface areas of the support do not seem to affect the catalytic activity.

• Journal of Powder Materials
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• v.20 no.6
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• pp.467-473
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• 2013

This research presents a preparation method of dental components by metal injection molding process (MIM process) using titanium scrap. About $20{\mu}m$ sized spherical titanium powders for MIM process were successfully prepared by a novel dehydrogenation and spheroidization method using in-situ radio frequency thermal plasma treatment. The effects of MIM process parameters on the mechanical and biological properties of dental components were investigated and the optimum condition was obtained. After sintering at $1250^{\circ}C$ for 1 hour in vacuum, the hardness and the tensile strength of MIMed titanium components were 289 Hv and 584 MPa, respectively. Prepared titanium dental components were not cytotoxic and they showed a good cell proliferation property.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.515-520
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• 2007

Recently, the treat of sludge is usually progressed by ocean disposal. But it will be totally banned by content of its heavy metal according to London Dumping Convention, gradually. The stable way of treat of sewage sludge should be examined urgently. To solve the problem, recently, there are efficient and environment-oriented method. One of them is to produce absorbent through the activation. This study produces absorbent through steam activation. As basic experiment, optimum activation condition for preparation of good absorbent is researched through study of the fellowing variables : steam flow rate, activated temperature, activation time. As the result of this with standard on iodine adsorptivity, it is chosen, that steam flow rate "30 mL/hr", activation temperature $"500^{\circ}C"$, activation time "60 minutes". At the time, iodine adsorptivity and yield shown that 228.4 mg/g, 77.23%. And also, by using nitrogen adsorption, SEM and EDS are confirmed that pore development, specific surface area, mean pore size, chemical component and content. Pore developed by steam activation is also confirmed that it is micropore.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.197-206
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• 1990

1, 2-Disubstituted imidazolines, such as 1-behenoyl-aminoethyl-2-heneicosylimidazoline(BHI), 1-behenoylbis(aminoethyl)-2-heneicosylimidazoline(BBI), and 1-behenoyltris(aminoethyl)-2-henoicosylimidazoline(BTI) were synthesized by reacting 3 kinds of polyalkylene polyamines with behenic acid to provide the softness to imidazoline ring.1, 2-Disubstituted imidazolinium chlorides, such as 1-behenoyl-aminoethyl-1-glycidyl-2-heneicosylimidazolinium chloride(BHIC), 1-behenoylbis(aminoethyl)-1-glycidyl-2-henoicosylimidazolinium chloride(BBIC), and 1-behenoyltris(aminoethyl)-1-glycidyl-2-henoicosylimidazolinium chloride(BTIC) were prepared by quaternizing 1, 2-disubstituted imidazoline compounds. The optimum condition for the preparation of BHI, BBI, and BTI was 8 hrs at $210^{\circ}C$. In the synthesis of BHIC, the completely quaternized product was obtained by reacting BHI-epichlorohydrin with 1:1.3 mole ratio, and mole ratios higher than 1:1.5 were required in the preparation of BBIC and BTIC, BHICS, BBICS, and BTICS softners form BHIC, BBIC, and BTIC was treated to acrylic fiber. It was found that were good softners as the softening property was measured.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.301-307
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• 1997

Monodisperse, spherical $SiO_2/TiO_2$ composite fine powders were prepared by modified Sol-Gel process which $TiO_2$ fine Powders was used as a seed particles for condensation of TEOS (Tetraethyl Orthosilicate). The reaction was carried out under $N_2$ atmosphere at ambient temperature using $NH_3$ as a catalyst. Ethanol was used as a solvent. Drying process was carried out with vacuum trap which cooled by liquid $N_2$. The reaction variables were the concentration of TEOS, the concentration of ammonia, the size of $TiO_2$ seed and molar ratio of $SiO_2/TiO_2$. The optimum condition for the preparation of $SiO_2/TiO_2$ composite fine powders without agglomeration was [TEOS]=0.3M, [$NH_3$]=0.7M, size of $SiO_2/TiO_2$ seed = 200~300nm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.792-796
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• 2015

With high integration of electronic components, power inductors are also miniaturized. Recently, thick film processes for small size power inductors were developed and commercialized. However, the thick film process to prepare soft magnetic green sheets was not reported enough. In this study, we used Fe-Si magnetic and CIP (carbonyl iron powders) as starting materials to lead to a bimodal particle size distribution in the sheet. We proposed a newly developed 'Modified slurry preparation process' to get well dispersed condition even at high solid contents. Using the new process, it was possible to prepare a well dispersed slurry over 70 vol% of solid. BYK-103 was better than BYK-111 as dispersant in this slurry and the optimum amount was 0.6 wt%. The optimized slurry was formed into a sheet by tape casting process and then the sheet was laminated. We conformed that small size powder, large size powder, and epoxy resin were well dispersed in the green sheet.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.6
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• pp.357-362
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• 2015

A novel $TiO_2$-Coconut Shell Powder Composite (TCSPS), prepared by the controlled sol-gel method with subsequent heat treatment, was evaluated as an innovative photocatalytic absorbent for the removal of methylene blue. Optimal preparation conditions of TCSPC were obtained by a response surface methodology and a central composite design model. As compared with the results obtained from one-factor-at-a-time experiments, the values were approximated to the nearest condition of these values and the following experimental parameters were set as the optimum : $600^{\circ}C$ calcination temperature and 20 g of coconut shell powder loading amount.

• Polymer(Korea)
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• v.28 no.2
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• pp.128-134
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• 2004

Cellulose nanoparticles loaded with vitamin I acetate were prepared by modified spantaneous emulsification solvent diffusion method. After cellulose derivatives were dissolved in mixed acetone/ethanol organic solvent with vitamin E acetate, cellulose nanoparticle suspensions were dispersed in poly(oxyethylene sorbitane monooleate) solution using ultrasonicator. Particle size and loading amount of vitamin I acetate were measured by particle size analyser and UV-spectrometer, respectively. The stability of nanoparticle was determined by measuring the change of the particle size at room temperature for 30 days and the morphology was observed by SEM. Morphology of cellulose nanoparticles was spherical and particle size was not changed at room temperature for 30 days. The optimum condition for the preparation of cellulose nanoparticles was 1% w/v cellulose nitrate with 8% w/v poly(oxyethylene sorbitane monooleate) solution. It showed that particle size and loading amount of vitamin E acetate was 65nm and 71%, respectively.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.269-279
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• 1996

The porous armophous catalysts, composed of $SiO_2-TiO_2-V_2O_5$ were prepared through SOL-GEL process by differing the preparation parameters. Selected the optimum SOL-GEL catalyst which has the best NO removal activity through the screening test, and repeated coating it on the cordierite monolith which is the freely through and inert. And examined the NOx, SOx simultaneous removal effect under S. C. R. condition. In addition to its characterization performances by the DTA, TGA, BET, $NH_3$ and NO TPD, ESCA, XRD etc.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.405-411
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• 2007

This study was carried out to measure insoluble phosphorus fractions content fixed in different soil type and isolate a superior phosphate solublizing bacteria(PSB) producing free phosphate in citrus orchard soil. Distribution of insoluble phosphate fraction ordered Al-P>Ca-P>Fe-P in the investigated citrus orchards. Insoluble phosphate fraction such as Al-P, Ca-P, Fe-P were higher in volcanic ash than in non-volcanic ash soil. A PSB with high holo zone in PDA-P medium isolated from citrus orchard soil. This strain identificated by MIDI system as Bacillus sphaericus. The optimum growth of pH and temperature were at 4~5, $30^{\circ}C$, respectively. When Bacillus sphaericus cultured at $25^{\circ}C$, 150 rpm condition in LB broth medium included different phosphate. Bacillus sphaericus produced free phosphate in the culture broth medium from tricalcium-phosphate(207.0 ppm), aluminium phosphate(324.5 ppm) and hydroxyapatite(334.8 ppm) and Phosphatase activity of Bacillus sphaericus was higher at $35^{\circ}C$ culture condition than that of $25^{\circ}C$. Two type preparation inoculated Bacillus sphaericus made with carrier materials such as Bentonite, $CaCO_3$, Sodium alginate. Density of PSB in this preparation conserved at $10^5c.f.u.\;g^{-1}$ level during storage in different temperature condition for 7 month. It also showed that free phosphate produced at PDA-P medium.