• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.144-150
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• 2008

Recently, there has been growing interest in low loss and low dielectric constant material for LTCC application, as the frequency range for electronic devices increases. This study was designed to evaluate the effect of cordierite filler for low dielectric constant LTCC material. From the previous experiments, two glass compositions of B-Si-Al-Zn-Ba-Ca-O and B-Si-Al-Sr-Ca-O system, were chosen. Each powder of two glass compositions was sintered respectively with commercial cordierite powder in temperature range from $800^{\circ}C\;to\;900^{\circ}C$. Crystalline cordierite and glass peaks were affected only with two factors of composition and sintering temperature among various factors. With the optimized condition of two cordierite/glass compositions, obtained dielectric constant was below 5.5 and quality factor was above 1,000. Closed pore of sintered body was controled by sintering temperature and sintering time. When cordierite/glass composite with ratio of 5.5:4.5 was sintered at $900^{\circ}C$, densification was sufficient with good dielectric characteristics of ${\epsilon}_r<5.1,\;Q{\ge}1,000$. Residual fine closed pores could be reduced with control of sintering temperature and time. 3 point bending strength and chemical durability were evaluated to obtain feasibility for substrate material.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.3
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• pp.217-225
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• 1993

Nonflammable mixtures of flammable and nonflammable refrigerants are possible as substitute refrigerants for use in domestic heat pumps and refrigerators. Refrigerant leakage from such a system is of paramount concern since it is possible that the resulting mixture composition remaining in system will reside in the flammable range. This paper presents a simulation of a leakage process of refrigerant mixtures. Idealized cases of isothermal leakage process are considered in this study representing a slow leak. Simulation is performed for selected composition of binary and ternary refrigerant mixture; R-32/134a and R-32/125/134a. Mixture compositions with respect to percentage leak of original charge are presented. In isothermal leakage process, both vapor and liquid compositions of more volatile refrigerant decrease during vapor and liquid leak, but the total composition of this component decreases during vapor leak and increases during liquid leak. Vapor and liquid compositions are determined depending on the vapor-liquid equilibrium relation of the refrigerant mixture. The refrigerant mixture left in the system can go to a nonflammable direction relying on which component in the mixture is flammable.

• Phonetics and Speech Sciences
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• v.2 no.2
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• pp.63-68
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• 2010

A new version of sequential probability ratio test (SPRT) which has been investigated in utterance-length control is proposed to obtain uniform response results in speaker verification (SV). Although SPRTs can obtain fast responses in SV tests, differences in the performance may occur depending on the compositions of consonants and vowels in the sentences used. In this paper, a fast sequential probability ratio test (FSPRT) method that shows consistent performances at all times regardless of the compositions of vocalized sentences for SV will be proposed. In generating frames, the FSPRT will first conduct SV test processes with only generated frames without any overlapping and if the results do not satisfy discrimination criteria, the FSPRT will sequentially use frames applied with overlapping. With the progress of processes as such, the test will not be affected by the compositions of sentences for SV and thus fast response outcomes and even consistent performances can be obtained. Experimental results show that the FSPRT has better performance to the SPRT method while requiring less complexity with equal error rates (EER).

• Korean Journal of Materials Research
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• v.15 no.12
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• pp.773-779
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• 2005

Properties of Ni-base superalloys of Nimonic 80A alloy system were investigated by the observation of microstructures, precipitates ana hardness as a function of the chemical compositions ana the paths of heat treatment. The higher hardness values showed, the higher Ti/Al ratio among high compositions of Cr and Co element. The lower (Ti+Al) and Fe contents decreased in the same Ti/Al ratio, the higher hardness values showed. This results are considered that coherent deformation was increased with increasing Ti/Al ratio. Hardness showed higher value when Cr contents was $18 wt\%$ less than $21wt\%Cr$. In $3.15 wt\%$Co alloy, $\gamma'$ phase was very fine as around 50nm and, its volume fraction and hardness showed the highest value by 2step-aging treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.280-285
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• 1995

To develop natural food preservatives, antimicrobial effect of the ethanol extract of leaf mustard against E. coli and S. aureus were examined in terms of compositions and leakage of cellular materials in the microorganisms treated with the extract. No effect of the concentration of ethanol extract on the fatty acid composition of E. coli and S. aureus at logarithmic phase was showen, but the content of palmitic and palmitoleic acid of E. coli slightly increased and decreased, respectively, and the content of palmitic and margaric acid of S. aureus slightly increased, when compared to each control. Ethanol extract did not affect most of the amino acids E. coli and S. aureus at logarithmic phase ; however, some of them(proline, glycine, valine and histidine of E. coli and proline, methionine and histidine of s. aureus) were elevated and some other amino acid(aspartic acid, glutamic acid, tyrosine and arginine of E. coli and aspartic acid, glutamic acid, glycine, alanine and lysine of Staph. aureus) found to be decreased. The amount of cell body protein leaked from E. coli and S. aureus increased to 1.02 and 0.22mg/g cell weight, respectively, as compared to controls. Similarly, the substances with absorbance at 260 nm from E. coli and s. aureus increased to 0.12 and 0.06mg/g cell weight, respectively.

• Korean Journal of Microbiology
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• v.23 no.4
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• pp.252-258
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• 1985

Aspergillus niger var. macrospours, Aspergillus fumigatus, Penicillium notatum and Penicillium spinulosum were cultured under different cultural conditions. The lipids produced by these species and fatty acid compositions of lipids were investigated. The macimum lipid contents produced by each species were 17.8% for Asp. niger var. macrosporus, 31% for Asp. fumigatus, 12.6% for P. notatum and 17.5% for P. spinulosum, respectively. The major fatty acid compositions were palmitic acid, stearic acid, oleic acid and linoleic acid. Asp. niger var. macrosporus and Asp. fumigatus were highest oleic acid during all incubation periods and P. notatum and P. spinulsum were linoleic acid. Degree of unsaturation was higher Penicillium than Aspergillus. The fatty acid compositions were changed depending on the incubation temperature, but hardly showed a certain tendency except linoleic acid and degree of unsaturation that were higher at lower temperature.

• Journal of Nutrition and Health
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• v.26 no.5
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• pp.547-557
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• 1993

This study was done to investigate whether dietary fats differing in their fatty acid compositions change hepatic mitochondrial lipid composition and thereby change adenine nucleotide translocase activity. Male Sprague-Dawley rats were fed 5 different wxperimental diets for 6 weeks, which were different in their fatty acid compositions. The dietary fats were beef tallow(BT), olive oil(OO), corn oil(CO), perilla oil(PO) and sardine oil(SO) as a source of saturated fatty acid, oleic acid, n-6 linoleic acid, n-3 $\alpha$-linolenic acid and n-3 eiocosapentaenoic acid+docosahexaenoic acid respectively. Body weight of PO group was significantly higher than that of either BT or SO group. This increase in body weight of PO group was due to the increase of food intake. Although there was no difference in liver weight, % liver weight per body weight of SO group was significantly higher than BT and OO groups. Analysis of mitochondrial lipid composition showed that dietary oils differing their fatty acid compositions altered mitochondrial fatty acid patterns, especially n-6/n-3 ratio, cholesterol/phospholipid ratio and phopsholipid composition. The n-6/n-3 ratio was highest in CO group but lowest in SO group whereas the ratio of Chol/PL was highest in SO group but lowest in CO group. Such changes in mitochondrial lipids did not lead to a significant alteration in the activities of adenine nucleotide translocase, which is embedded in mitochodrial inner membrane.

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.934-938
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• 1995

A series of solid solutions in the Ca2AlxFe2-xO5 (x=0.00, 0.50, 0.66, 1.00 and 1.34) system with brownmillerite structure has been synthesized at 1100 ℃ under an atmospheric air pressure. The solid solutions are analysed by powder x-ray diffraction analysis, Mohr salt titration, thermal analysis, and Mossbauer spectroscopic analysis. The x-ray diffraction analysis assigns the compositions of x=0.00 and 0.50 to the space group Pcmn and those of x=0.66, 1.00, and 1.34 to the Ibm2. Mo&ssbauer spectra have shown the coordination state and disordering of Al3+ and Fe3+ ions. The substituting preference of Al3+ ions for the tetrahedral site decreases with increasing x value. Magnetic susceptibility of the system has been measured in the temperature range of 5 K to 900 K. The solid solutions of the compositions of x=0.00, 0.50 and 0.66 have shown a thermal hysteresis and the thermoremanent magnetization gap decreases with increasing x value in the above systems. However the compositions of x=1.00 and 1.34 do not show the hysteresis. The exchange integral is calculated from Fe3+ ion occupancy ratio. The integral decreases with x value and thus the magnetic transition temperature decreases with the increasing x value.

• Nuclear Engineering and Technology
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• v.47 no.7
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• pp.924-933
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• 2015

The correlation of the isotopic composition of uranium, plutonium, neodymium, and cesium with the burnup for high burnup pressurized water reactor fuels irradiated in nuclear power reactors has been experimentally investigated. The total burnup was determined by Nd-148 and the fractional $^{235}U$ burnup was determined by U and Pu mass spectrometric methods. The isotopic compositions of U, Pu, Nd, and Cs after their separation from the irradiated fuel samples were measured using thermal ionization mass spectrometry. The contents of these elements in the irradiated fuel were determined through an isotope dilution mass spectrometric method using $^{233}U$, $^{242}Pu$, $^{150}Nd$, and $^{133}Cs$ as spikes. The activity ratios of Cs isotopes in the fuel samples were determined using gamma-ray spectrometry. The content of each element and its isotopic compositions in the irradiated fuel were expressed by their correlation with the total and fractional burnup, burnup parameters, and the isotopic compositions of different elements. The results obtained from the experimental methods were compared with those calculated using the ORIGEN-S code.

• Cross-Cultural Studies
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• v.19
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• pp.359-388
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• 2010

This study is aimed to investigate the aspect of using relative clauses in Korean. The data used for this study were extracted from the Korean text books for the foreign students and from the Chinese students' Korean compositions. They are the learners of Korean language at the early intermediated stage. As the result of analyzing them, the followings were found I)the majority of relative clauses in Korean consists of left-branching sentences. ii)The number of the subject relative clauses was higher than object ones in both of them. Especially in the aspect of using relative clauses, subject ones were used even more frequently than objective ones. This result is corresponded to the previous thesis, "the subject relative clauses was acquired earlier than object ones". iii)The relative clauses that those with a head noun function as subject in the main sentence showed in higher proportion in comparison of those as object. That is, this study showed that subjects were used more frequently than objects in the relative clauses used in their compositions. Finally, this study analyzed the errors of adnominal ending usage occurring in their compositions. More errors occurred when adjective form ended with '-hada' are changed into adnominal ending one.