• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.380-384
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• 2012

This paper deals with the recent developments of high thermal conductivity silicon nitride ceramics. First, the factors that reduce the thermal conductivity of silicon nitride are clarified and the potential approaches to realize high thermal conductivity are described. Then, the recent achievements on the silicon nitride fabricated through the reaction bonding and post sintering technique are presented. Because of a smaller amount of impurity oxygen, the obtained thermal conductivity is substantially higher, compared to that of the conventional gas-pressure sintered silicon nitride, while the microstructures and bending strengths are similar to each other between these two samples. Moreover, further improvement of the thermal conductivity is possible by increasing ${\beta}/{\alpha}$ phase ratio of the nitrided sample, resulting in a very high thermal conductivity of 177 W/($m{\cdot}K$) as well as a high fracture toughness of 11.2 $MPa{\cdot}m^{1/2}$.

• Korean Journal of Veterinary Research
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• v.31 no.2
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• pp.223-228
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• 1991

Most progesterone enzyme immunoassays(EIA) are used liquid-phase double-antibody or single-antibody seperation. These methods consume considerable time and reagents because of the requirements for several washing and centrifugation steps involving the reactants. Because of these several problems, we were prompted to develop an effective enzyme-linked immunosorbent assay(ELISA) system that would be equal or superior to RIA for assay of progesterone. The results were obtained as follows. 1. Cross reaction of the progesterone antiserum with other steroids determined was shown with progesterone(100%), $11{\alpha}$-deoxycorti-costerone(2.271%), but the other steroids were shown below 0.9%. 2. Standard curve for progesterone ELISA was shown available difference according to progesterone concentration from 0 to 1,000pg/ml. 3. The lower limit of sensitivity was 0.2pg/well 4. Progesterone concentration was 1.6ng/ml for before parturition, and that was below 0.5ng/ml for after parturition. This development enzyme-linked immunosorbent assay for progesterone can be detected pregnancy diagnosis in cattle, and also applicable 10 research on physiological function including such as reproductive disorders.

• KSBB Journal
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• v.26 no.4
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• pp.323-327
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• 2011

The convenient derivatization method of chiral amino alcohols as 9-anthraldimine Schiff base derivatives for chiral resolution was developed and the liquid chromatographic enantiomer separation of chiral amino alcohols as 9-anthraldimine derivatives was investigated on several coated and covalently bonded polysaccharide-derived chiral stationary phases (CSPs). In general, the performance of Chiralcel OD-H (or Chiralcel OD) (${\alpha}$ = 1.24-2.89), the coated CSP derived from cellulose derivative was superior to the other CSPs for resolution of 9-anthraldimine derivatives of several amino alcohols. The results of enantioseparation depending on the structure of 9-anthraldimine analytes like the steric bulky group and the polar moiety etc were discussed. The analytical method was applied to measure the enantiomeric purity of commercially available chiral amino alcohols. It is expected that the convenient analytical method will be very efficient for determination of enantiomeric purity of amino alcohols as 9-anthraldimine Schiff base derivatives with strong UV absorption.

• Transactions on Electrical and Electronic Materials
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• v.13 no.5
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• pp.262-265
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• 2012

The Microstructure and nonlinear electrical properties of the ZPCCYT (ZnO-$Pr_6O_{11}$-CoO-$Cr_2O_3$-$Y_2O_3$-$Tb_4O_7$) varistors were investigated for different amounts of $Tb_4O_7$. The addition of $Tb_4O_7$ has a significant effect on microstructure and electrical properties. Analysis of the microstructure indicated that the ceramics consisted of ZnO grain as a main phase and a few secondary phases as a mix of $Pr_6O_{11}$, $Y_2O_3$, and $Tb_4O_7$. As the amount of $Tb_4O_7$ increased, the sintered densities of pellets increased from $\rho$ = 5.70 to $5.78g/cm^3$ and the average grain size decreased from d = 4.8 to $3.6{\mu}m$. The increase in the amount of $Tb_4O_7$ increased from $E_B$ = 7,473 to 10,035 V/cm and from ${\alpha}$ = 39.7 to 52.2. In particular, it was found that the ceramics modified with 1.0 mol% in the amount of $Tb_4O_7$ are suited for the varistors for high voltage in the light of a high sintered density and a high voltage gradient.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.10
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• pp.1459-1464
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• 2004

The purpose of this research was to investigate the potential use of cheese whey protein (CWP), a cheese by-product. The physiological activity of calcium-binding peptides in CWP may be used as a food additive that prevents bone disorders. This research also examined the characteristics of calcium-binding peptides. After the CWP was heat treated, it was hydrolyzed by trypsin. Then calcium-binding peptides were separated and purified by ion-exchange chromatography and reverse phase HPLC, respectively. To examine the characteristics of the purified calcium-binding peptides, amino acid composition and amino acid sequence were analyzed. Calcium-binding peptides with a small molecular weight of about 1.4 to 3.4 kDa were identified in the fraction that was flowed out from 0.25 M NaCl step gradient by ion-exchange chromatography of tryptic hydrolysates. The results of the amino acid analysis revealed that glutamic acid in a calcium-binding site took up most part of the amino acids including a quantity of proline, leucine and lysine. The amino acid sequence of calcium-binding peptides showed Phe-Leu-Asp-Asp-Asp-Leu-Thr-Asp and Ile-Leu-Asp-Lys from $\alpha$-LA and Ile-Pro-Ala-Val-Phe-Lys and Val-Tyr-Val-Glu-Glu-Leu-Lys from ${\beta}$-LG.

• Journal of Korean Academy of Nursing
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• v.35 no.6
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• pp.1063-1071
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• 2005

Purpose: This study was done to develop and test validity and reliability of on instrument for predicting nursing intention for SARS patient care. Method: The psychometric properties of a SARS patient care attrition prediction tool, based on the Theory of Planned Behavior, were examined in this study. The Three-phase design involved a) salient beliefs generated from clinical nurses (n=43) b) content validation by expert panel evaluations(n=5) c) face validation by plot testing (n=10) d) and instrument validation in a cross sectional survey (n=299). Psychometric analysis of survey data provided empirical evidence of the construct validity and reliability of the instrument. Result: Principal component analysis verified the hypothesized 6-factor solution, explaining $68.2\%$ of variance, and Alpha coefficients of .7538 to .9389 indicated a high internal consistency of the instrument. Conclusion: The instrument can be used by nurse administrators and researcher to assess clinical nurses' salient beliefs about caring for SARS patients, guide tailored intervention strategies to effective caring, and evaluate the effectiveness of interventions.

• Journal of Powder Materials
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• v.22 no.1
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• pp.32-38
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• 2015

The effect of heat treatment environment on the microstructure and properties of tantalum coating layer manufactured by kinetic spraying was examined. Heat treatments are conducted for one hour at $800^{\circ}C$, $900^{\circ}C$, and $1000^{\circ}C$ in two different environments of vacuum and Ar gas. Evaluation of microstructure and physical properties are conducted. High density ${\alpha}$-tantalum single phase coating layer with a porosity of 0.04% and hardness of 550 Hv can be obtained. As heat treatment temperature increases, porosity identically decreases regardless of heat treatment environment (vacuum and Ar gas). Hardness of heat treated coating layer especially in Ar gas environment deceases from 550 Hv to 490 Hv with increasing heat treatment temperature. That in vacuum environment deceases from 550 Hv to 530 Hv. The boundary between particles became vague as heat treatment temperature increases. Oxygen distribution of tantalum coating layer is minute after heat treatment in vacuum environment than Ar gas environment.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.677-681
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• 1999

For the binary cyclohexanol-cyclohexanone system the vapor-liquid equilibrium data, which are the necessary ones for the design of the distillation columns in separation process of volatile liquid-mixtures, are measured at subatmospheric pressure of 150, 300 and 500 mmHg. An empirical relation between logarithmic values of relative volatility(log $\alpha$) and liquid phase composition(x), which predicts the vapor-liquid equilibrium data, is obtained from above measured data of 150, 300 and 500 mmHg and the published ones of 30, 100, 200, 395 and 750 mmHg. The predicted data are compared with the measured and published ones to be in good agreement.

• Hwankyungkyoyuk
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• v.21 no.4
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• pp.79-93
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• 2008

The purpose of this study was to develop an instrument for measuring elementary school students' environmental literacy. The process of instrument development was four phases. The first two phases involved defining the domain of the construct, writing an initial pool of 55 items, and reviewing the items for revision and deletion. These steps were taken to provide the evidence of content-related validity, and to reduce a number of items. The third phase was, through item analysis, to determine the most appropriate items for the environmental literacy for the elementary school students. For the forth phases, the fifth and sixth students in elementary school participated in this survey. To examine the reliability and validity of environmental literacy for the elementary school students, internal consistency estimate, and factor analysis were used. The results of this study were summarized as follows; Firstly, thorough factor analysis, we developed Environmental Literacy Instrument for the elementary school students, consisted of total 41 items (knowledge 8 items, emotion 11 items, skill 10 items, and behavior 13 items); Secondly, Cronbach's alpha was .783 for knowledge, .832 for emotion, .866 for skill and 8.61 for behavior.

• KSBB Journal
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• v.16 no.3
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• pp.295-301
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• 2001

The leaching effect of Thiobacillus ferrooxidance (ATCC 19859) upon polished pyrite ore in 9K medium at $30^{circ}C$ for 30 days was investigated. The surface atomic ratios for Fe, S, Al, Si, and Cu were analyzed by EPMA using fresh and leached samples. The atomic ratio of Fe and S were changed to Fe rich phase as leaching progressed over 13 days but the Fe/S ratio became constant between 13 and 30 days. SEM imaging showed that $10\mum$ oblong shapes formed on the surface after 13 days and that these further developed until 23 days. Fe, S and K atomic ratios were analyzed by SEM-EDS.