• Journal of Dairy Science and Biotechnology
• /
• v.25 no.1
• /
• pp.9-13
• /
• 2007

The present study was carried out to examine the effect of crosslinked ${\beta}$-cyclodextrin(${\beta}$-CD) made by adipic acid on cholesterol removal rate and find the structural change after recycling on SEM observation. The size reduction and morphological changes were found during the recycling process and the profound changes were observed at 8th time reuse. After cholesterol removal in milk, the used crosslinked ${\beta}$-CD was washed for cholesterol dissociation and reused. In recycling study, the cholesterol removal rate at first trial was 92.5% in milk, which was mostly same as that using new crosslinked ${\beta}$-CD(92.4%). With repeated 10th reuse of crosslinked ${\beta}$-CD resulted in 81.4% of cholesterol removal in milk. Similar trend was found in cream and cholesterol removal was 91.5% at 1st trial and 83.4% at 10th trial. In both milk and cream samples, the removal rate at 1st reuse was not significantly different from that at 6th reuse(p>0.05). The present study indicated that crosslinked ${\beta}$-CD made by adipic acid resulted in the effective recycling efficiency, especially up to 6th reuse and morphological modifications were not distinguishable up to 8th reuse.

• Journal of the Korean institute of surface engineering
• /
• v.49 no.3
• /
• pp.238-244
• /
• 2016

Copper electrodeposition on AZ91 Mg alloy was studied in views of preferential deposition on ${\alpha}$- or ${\beta}$- phases and how to achieve uniform deposition over the entire surface on ${\alpha}$- and ${\beta}$-phases in a cyanide solution. The inhomogeneous microstructure of AZ91 Mg alloy, particularly ${\alpha}$- and ${\beta}$-phases, was found to result in non-uniform deposition of zincate layer, preferential deposition of zincate on ${\beta}$-phases, which leads to non-uniform growth of copper layer during the following electrodeposition process. The preferential depositions of zincate can be attributed to higher cathodic polarizations on the ${\beta}$-phases. Pin-hole defects in the copper electrodeposit were observed at the center of large size ${\beta}$-phase particles which is ascribed to gas bubbles formed at the ${\beta}$-phases. The activation of AZ91 Mg alloy in hydrofluoric acid solution was used to obtain uniform growth of zincate layer on both the ${\alpha}$- and ${\beta}$-phases. By choosing an optimum activation time, a uniform zincate layer was obtained on the AZ91 Mg alloy surface and thereby uniform growth of copper was obtained in a cyanide copper electroplating solution.

• Microbiology and Biotechnology Letters
• /
• v.45 no.4
• /
• pp.277-283
• /
• 2017

To produce sweet liquor without artificial sweeteners, 8 traditional rice pre-treatment methods (juk, beombeok, seolgitteok, gumeongtteok, mulsongpyeon, injeolmi, gaetteok, and godubap) were analyzed in this study. The formation of sugars with the help of ${\alpha}$-amylase, ${\beta}$-amylase, and glucoamylase using nuruk as a substrate has been previously confirmed. During the early stages of the pre-treatment processes, the amount of maltose produced (in descending order of its concentration) by ${\alpha}$-amylase was observed to be as follows: gaetteok > seolgitteok > beombeok > mulsongpyeon > juk > injeolmi > gumeongtteok > godubap. However, changes in maltose concentrations with respect to the pre-treatment processes after 48 hours were observed to be as follows: injeolmi > beombeok = godubap > gumeongtteok > gaetteok = mulsongpyeon > seolgitteok > juk. Maltose produced using either ${\alpha}$-amylase or ${\beta}$-amylase showed similar results. Glucoamylase produced 10 mg/ml of glucose during the godubap process, which was the highest amount of glucose among all the methods. Moreover, when ${\alpha}$-amylase, ${\beta}$-amylase, and glucoamylase were used concurrently, glucoamylase increased glucose production in the later stages. Therefore, the possibility of producing sweet liquor without employing artificial sweeteners was confirmed, even if the amount of sugar in the liquor varied with the pre-treatment process.

• Journal of the Korean Vacuum Society
• /
• v.8 no.3A
• /
• pp.194-200
• /
• 1999

In this paper studied was the piezoelectric properties of the $\beta$-PVDF organic thin films prepared by physical vapour deposition method. The molecular orientation of organic thin films was controlled by the application of an electric field and variation of substrate temperature during the evaporation process. Optimum conditions of manufacturing $\beta$-PVDF organic thin film by physical vapor deposition method is to keep at the substrate temperature of $80^{\circ}C$, at the applied electric field of 142.8 kV/cm. The voltage output coefficient increased from 1.39 to 7.04V increasing the force moment.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.4 no.4
• /
• pp.9-17
• /
• 2000

The crystal growth and dissolution rates were calculated by solving a model equation, which involved the dissolution of the metastable phase($\beta$-HNIW) and growth of the stable phase($\varepsilon$-HNIW), together with the mass balance equation. The model has been successfully used to simulate available kinetic data for the $\beta$$\longrightarrow$$\varepsilon$ polymorphic transformation via a solution phase. From the effectiveness factor based on the two-step model, it was found that the surface integration contribution to the process was comparatively small, and a diffusion dependency decreased with an increase of the mass fraction of chloroform in the mixed solvents of ethyl acetate and chloroform. Appling these kinetics in process simulation allowed for the prediction of the product size of $\varepsilon$-HNIW.

• Journal of the Korean Society for Heat Treatment
• /
• v.32 no.2
• /
• pp.68-73
• /
• 2019

${\alpha}$-titanium alloy has a relatively low heat treatment characteristic and it is mainly subjected to heat treatment for residual stress, recovery or dynamic recrystallization. In this study, commercially pure titanium hollow castings was fabricated by gravity casting. Heat treatments were carried out at $750^{\circ}C$, $850^{\circ}C$ and $950^{\circ}C$ to investigate the effect of post-heat treatment on microstructure and mechanical properties. Beta-transus temperature ($T_{\beta}$) was about $913^{\circ}C$, and equiaxed microstructure was shown at temperature below $T_{\beta}$ and lath-type microstructure at temperature above $T_{\beta}$. Microstructure and mechanical properties did not show any significant difference in the direction of solidification for titanium hollow billet, so it can be seen that it was a well-made material for extrusion process. The optimum heat treatment condition of hollow billet castings for the seamless tube production was $850^{\circ}C$, 4 hr, FC, indicating a combination of equiaxed microstructure and appropriate mechanical properties.

• Journal of Korean Society for Quality Management
• /
• v.45 no.2
• /
• pp.209-225
• /
• 2017

Purpose: Since traditional p chart is unable to deal with the variation of attribute data, this paper proposes a new attribute control chart for nonconforming proportions incorporating overdispersion with a beta-binomial model. Methods: Statistical theories for control chart developed under the beta-binomial model and a new approach using this control chart are presented Results: False alarm probabilities of p chart with the beta-binomial model are evaluated and demerits of p chart under overdispersion are discussed from three examples. Hence a concrete procedure for the proposed control chart is provided and illustrated with examples Conclusion: The proposed chart is more useful than traditional p chart, individual chart to treat observed proportions nonconforming as variable data and Laney p' chart.

• Journal of Powder Materials
• /
• v.6 no.3
• /
• pp.246-250
• /
• 1999

The effects of the ${\beta}-Si_3N_4$ starting particle size and $\alpha$/$\beta$ phase transformation during sintering process on the microstructure evolution of Yttrium $\alpha$-Sialon ceramics were investigated. As-received ${\beta}-Si_3N_4$ powder (mean particle size: 0.54$\mu$m) and classified ${\beta}-Si_3N_4$ powder(mean particle size: $0.26\mu{m}$) were used as starting powders. With decreasing the starting particle size, the growth of elongated grains was enhanced, which resulted in the whisker -like microstructure with elongated grains. These results were discussed in relation to the two-dimensional nucleation and growth theory. In the specimen heat treated at $1600^{\circ}C$ for 10h before sintering at $1950^{\circ}C$for 1h under 40atm(2-step sintering), the grain size was smaller than of the 1-step sintering at 195$0^{\circ}C$ for 1h. However, bimodal microstructure evolution were not not remarkable in both sample, which is ascribed to the $\alpha$-phase contents existing in ${\beta}-Si_3N_4$ starting powder.

• Journal of the Korean Society for Heat Treatment
• /
• v.24 no.4
• /
• pp.193-198
• /
• 2011

Effect of CaO addition on age hardening response has been studied by using optical microscopy, scanning electron microscopy and differential thermal analysis in AZ91 and CaO-containing ECO-AZ91 alloys. After solution treatment, the ${\beta}$($Mg_{17}Al_{12}$) phase formed during solidification mostly disappeared in the microstructure in the AZ91 alloy, whereas numerous ${\beta}$ precipitates containing Ca were still observed in the ECO-AZ91 alloy due to its enhanced thermal stability. The ECO-AZ91 alloy showed the delayed peak aging time and higher peak hardness compared with those of the AZ91 alloy. The activation energies for ${\beta}$ precipitation calculated by means of Kissinger method increased from 71.4 to 85.6 kJ/mole by the addition of CaO, which implies that CaO plays a role in reducing ${\beta}$ precipitation rate in the AZ91 alloy.

• The Korean Journal of Ceramics
• /
• v.3 no.3
• /
• pp.163-168
• /
• 1997

Most of heteroepitaxial $\beta$-SiC thin films have been successfully grown on Si(100) adapting a carburizing process, by which a few atomic layers of substrate surface is chemically converted to very thin SiC layer using hydrocarbon gas sources. Using an organo-silicon precursor, bis-trimethylsilymethane (BTMSM, [$C_7H_{20}Si_2$]), heteropitaxial $\beta$-SiC thin films were successfully grown directy on Si substrate without a carburized buffer layer. The defect density of the $\beta$-SiC thin films deposited without a carburized layer was as low as that of $\beta$-SiC films deposited on carburized buffer layer. In addition, void density was also reduced by the formation of self-buffer layer using BTMSM instead of carburized buffer layer. It seems to be mainly due to the characteristic bonding structure of BTMSM, in which Si-C was bonded alternately and tetrahedrally (SiC$_4$).