• Korean Journal of Materials Research
• /
• v.9 no.6
• /
• pp.589-594
• /
• 1999

The effect of $\beta$-heat treatment on th microstructure, mechanical properties and texture in the nuclear fuel cladding of Zircaloy-4 tubes was chosen at 1000, 1100 and 120$0^{\circ}C$, and the tubes were heat-treated by a high frequency vacuum induction furnace. Morphology of the second phase particles and $\alpha$-grain of as-received tubes were markedly changed by heat treatment. The average sizes of second phase particles of as-received and $\beta$-heat treated tubes were 0.1$\mu\textrm{m}$ and 0.076$\mu\textrm{m}$, respectively. However, the average sizes of second phase particles were not much changed in the $\beta$-heated temperatures. With increasing heat treatment temperatures, the 0.2% yield strength and the hoop strength were decreased because of changes in preferred orientation as will as $\alpha$-plate width. Heat treated Zircaloy-4 tubes exhibited texture changes but the preferred orientation of grains still remained.

• Bulletin of the Korean Chemical Society
• /
• v.8 no.5
• /
• pp.398-403
• /
• 1987

A general theory of polymer adsorption at a semi-permeable oil-water interface of the biphasic solution is presented. The configurational factor of the solution in the presence of the semi-open boundary at the interface is evaluated by the quasicrystalline lattice model. The present theory gives the feature of the bulk concentration equilibria between oil-water subsystems and the surface excesses of ${\Gamma}^{\alpha}$ and ${\Gamma}^\{beta}$ of the polymer segments as a function of the degree of polymerization $\gamma$, the Flory-Huggins parameter in $\beta$-phase $x_{\rho}^{{\beta}_{\rho}}$, the differential adsorption energy parameter in $\beta$-phase $x_{\sigma}^{{\beta}_{\rho}}$, the differential interaction energy parameter ${\Delta}x_{\rho}$ and the bulk concentration of the polymer in ${\beta}-phase ${\varphi}_2^{{\beta(*)}_2}$. From our numerical results, the characteristics of ${\Gamma}^{\alpha}$ are shown to be significantly different from those of ${\Gamma}^{\beta}$ in the case of high polymers, and this would be the most apparent feature of the adsorption behavior of the polymer at a semi-permeable oil-water interface, which is sensitively dependent on ${\Delta}x_{\rho}$ and r.

• Bulletin of the Korean Chemical Society
• /
• v.14 no.1
• /
• pp.9-11
• /
• 1993

• Bulletin of the Korean Chemical Society
• /
• v.12 no.6
• /
• pp.594-596
• /
• 1991

• Journal of Electrochemical Science and Technology
• /
• v.13 no.2
• /
• pp.321-321
• /
• 2022

• Journal of the Korean Ceramic Society
• /
• v.25 no.4
• /
• pp.380-384
• /
• 1988

This investigation includes nitridation phenomena of silicon powder compacts in air. Nitridation reaction condition has been provided with using silicon nitride bed and active carbon additive. Reaction products are Oxynitride, $\alpha$-Si3N4, and $\beta$-Si3N4, Oxynitride(Si2N2O) phase in formed at outer surface layer ofsilicon powder compacts. $\alpha$-Si3N4, and $\beta$-Si3N4 are formed at inner region of powder compacts. Microstructural observation indicates that nitridation mechanism in this work is the same as conventional nitridation mechanism nitrogen gas.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1994.04a
• /
• pp.327-327
• /
• 1994

본 연구에서는 간손상에 대한 해독제의 연구 및 안전성 평가연구로서 H$_2$-rcccptor길항제와 한방에서 건위역으로 이용되는 생약추출물 (생강, 정향 및 후박나무의 수피추출물, 강활, 시호, 토복령 및 금은화)이 화합물로 유발된 간독성에 미치는 효과를 고찰하였다. 또한 식물의 2차 대사산물로서 식품, 의약품 및 화장품 향신료 등의 첨가제로 이용되는 monotcrpcnoids중 $\alpha$-pinene, limonenc, gcraniol 및 cincol 이 phase II 효소계중 glutathione S-transferase(GST)의 class alpha 및 mu family계 효소와 microsomal cpoxidc hydrolase(mEH)의 발현에 미치는 영향을 관찰하였다.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.399.1-399.1
• /
• 2002

The chiral stationary phase derived from (＋) (18-crown-6)-2.3, 11.12-tetracarboxylic acid (18-C-6- TA) as a chiral selector has been employed for resolution of several $\alpha$-amino acids in HPLC. In a quest for the origin of chiral recognition of $\alpha$-amino acids in the presence of 18-C-6- T, A, as a chiral selector, these interactions responsible for the differential affinities shown toward enantioners were investigated by NNR spectroscopy. (omitted)

• Microbiology and Biotechnology Letters
• /
• v.26 no.2
• /
• pp.187-194
• /
• 1998

Glycosides were synthesized using transglycosylation reaction of amylase in water system. Starch as a glycosyl donor and benzylalcohol as an acceptor were selected as substrates of transglycosylation reaction. Among tested 9 commercial amylase, amyloglucosidase from Rhizopus sp. had high activity for transglycosylation from starch. The glycoside synthesized in water phase by amyloglucosidase was identified as benzylalcohol-${alpha}$-glucoside (BG) of which one molecule of benzylalcohol was bound to 1-OH of glucose. The transglycosylation reaction by amyloglucosidase were carried out in reaction system containing 50 mg starch, 50 mg benzylalcohol, and 10 units enzyme in pH 5.0 at 45$^{\circ}C$. The synthesized BG was hydrolyzed by ${alpha}$-glucosidase to produce glucose and benzylalcohol.

• KSBB Journal
• /
• v.27 no.3
• /
• pp.167-171
• /
• 2012

A convenient liquid chromatographic enantiomer separation of several ${\alpha}$-amino acid esters as benzophenone Schiff base derivatives on covalently immobilized chiral stationary phases (CSPs) derived from polysaccharide derivatives was developed. The benzophenone imine derivatives of ${\alpha}$-amino acid esters were readily prepared by stirring benzophenone imine and the ${\alpha}$-amino acid ester hydrochloride salts in 2-propanol. The chromatographic conditions used on all CSPs were 0.5% or 5% 2-propanol/hexane (V/V) as the mobile phases at 1 mL/min of flow rate and UV 254 nm detection. The performance of Chiralpak IC among all CSPs was superior to that of the other CSPs for resolution of benzophenone imine derivatives of ${\alpha}$-amino acid esters. It is expected that the developed analytical method will be useful for enantiomer resolution of other ${\alpha}$-amino acid esters as benzophenone Schiff base derivatives.