• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.35-43
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• 1999

Microstructures and dielectric properties of (Sr$\_$1-x/Ca$\_$x/) TiO$_3$-0.006Nb$_2$O$\_$5/ (0.05$\leq$x$\leq$0.2) boundary layer ceramics were investigated. The samples fired in a reducing atmosphere(N$_2$) were painted on the surface with CuO paste for the subsequent grain boundary diffusion, and then annealed at 1100$^{\circ}C$ for 2 hrs. The metal oxide of CuO infiltrated by thermal diffusion from surface of sample presents continuously in not grain but only grain boundary, and makes up thin boundary phase. The SEM photo, and EDAX revealed that CuO was penetrated rapidly into the bulk along the grain boundaries during the annealing. The average grain sizes is continuously increased as the content of substitutional Ca is increased from 5[mol%] to 15[mol%], but the average grain size of the sample with content of 20[mol%] Ca is slightly decreased. In the samples with content of 10∼15[mol%] Ca, excellent dielectric properties were obtained as follows; dielectric constant <25000, dielectric loss <0.3[%], and capacitance change rate as a function of temperature <${\pm}$10[%], respectively. All samples in this study exhibited dielectric relaxation with frequency as a functior of the temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.155-155
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• 2010

Oxygen incorporated $Ge_2Sb_2Te_5$ (GST) films were prepared by an ion beam sputtering deposition (IBSD) method. From the I-V curves, the $V_{th}$ value varies with the oxygen content. Ge-deficient hexagonal phases are responsible for the observed unstability and decrease in $V_h$ values. In the case of a GST film with an elevated oxygen content of 30.8 %, the GST layer melted at 9.02 V due to the instability conferred by the high oxygen content. The formation of Ge-deficient hexagonal phases such as $GeSb_2Te_4$ and $Sb_2Te_3$ appear to be responsible for the $V_{th}$ variation. Impedance analyses indicated that the resistance in GST films with oxygen contentsof 16.7 % and 21.7 % had different origins. Thermal desorption spectroscopy (TDS)data indicate that moisture and hydrocarbons were more readily desorbed at higher oxygen content because the oxygen incorporated GST films are more hydrophilic than undoped GST films.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.6
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• pp.295-302
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• 2022

The present study aims to investigate the effect of Al content on microstructure and hardness of discontinuous precipitates (DPs) formed by continuous cooling (CC) in Mg-8%Al and Mg-9.5%Al alloys. The DPs had a wide range of (α+β) interlamellar spacings, which may well be attributed to the different transformation temperatures during CC. The higher Al content gave rise to the higher level of interlamellar spacings of the DPs, and thicker and larger amount of β phase layer in the DPs. It is noticeable that the Mg-9.5%Al alloy exhibited higher hardness of the DPs than the Mg-8%Al alloy, but the ratio of increase in hardness of the DPs compared to that of the as-cast state was similar regardless of the Al content. The reason was discussed based on the differences in microstructures of the DPs for the Mg-8%Al and Mg-9.5%Al alloys.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.6
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• pp.287-293
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• 2021

This study was intended to investigate the influence of Al content on hardness and microstructural characteristics of discontinuous precipitates (DPs) formed by isothermal aging in Mg-8.7%Al and Mg-10%Al alloys. In order to obtain large amount of DPs in the microstructure, the alloy specimens were solution-treated at 688K for 24 h followed by water quenching, and then aged at 418K for 48h. The Mg-Al alloy with higher Al content was characterized by higher volume fraction of DPs at the same aging condition, lower interlamellar spacing of the DPs, thinner β phase layer and higher β phase content in the DPs. This is closely related to the higher velocity of discontinuous precipitation process resulting from the higher Al supersaturation in the α-(Mg) matrix. The Mg-10%Al alloy showed higher hardness of the DPs and greater difference in hardness between as-cast state and DPs than the Mg-8.7%Al alloy.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.6
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• pp.449-452
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• 2001

Legume seed isoflavones may have a variety of desirable physiological effect on the human health including both the circulatory and skeletal systems. The present study was performed to determine the isoflavone content of leaf and seed as well as to purify and identify the types of isoflavone from leaf extract of hyacinth bean (Lablab purpureus (L.) Sweet). Reverse phase HPLC revealed six different types of isoflavone such as daidzin, genistin, daidzein, genistein, 6"-o-acetyl genistin and 6"-o-acetyl daidzin in aqueous methanol extract from seeds and leaves of the hyacinth bean. Relatively, leaf isoflavone content of hyacinth bean was greater than seed isoflavone content. Using DiAion HP-20 silica gel and sephadex LH-20 chromatography, pure daidzein was identified in the ether layer, whereas genistin was in the EtOAC fraction.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.1
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• pp.11-14
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• 2012

The AlGaN layer has direct wide bandgaps ranging from 3.4 to 6.2 eV. Nowadays, it is becoming more important to fabricate optical devices in an UV region for the many applications. The high quality AlGaN layer is necessary to establish the UV optical devices. However, the growth of AlGaN layer on GaN layer is difficult due to the lattice mismatch and difference thermal expansion coefficient between GaN layer and AlGaN layer. In this paper, we attempted to grow the LED structure on GaN template by mixed-source HVPE method with multi-sliding boat system. We tried to find the optical and lattice transition of active layer by control the Al content in mixed-source. For the growth of epi layer, the HCl and $NH_3$ gas were flowed over the mixed-source and the carrier gas was $N_2$. The temperature of source zone and growth zone was stabled at 900 and $1090^{\circ}C$, respectively. After the growth, we performed the x-ray diffraction (XRD) and electro luminescence (EL) measurement.

• Applied Biological Chemistry
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• v.31 no.2
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• pp.169-176
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• 1988

Lipid contents, fatty acid compositions and free sugar contents of dried ginsengs grown for different years were studied. The lipid and free sugar were separated and quantified by silicic acid column chromatography, thin layer chromatography, gas liquid chromatography and high performance liquid chromatography. Ginseng contained $1.07{\sim}67%$ crude lipid and the hightest lipid content was shown in 3 year old root. The lipid fractions obtained by silicic acid column chromatography were mainly composed of neutral lipid$(51.35{\sim}72.30%)$. The contents of phospholipid and glycolipid in total lipids were $15.03{\sim}34.59%$ and $11.83{\sim}20.72%$, respectively. As the ginseng grew, neutral lipid content increased gradually but glycolipid decreased to the half of the one year old root. Seven components of neutral lipid separated by thin layer chromatography were identified but the other two components were not able to be identified. Triglyceride content was $14.42{\sim}23.91%$, sterol ester and unidentified material(II) were $13.58{\sim}21.26%$ and $7.13{\sim}15.83%$ respectively. The major fatty acids were linoleic acid, palmitic acid, oleic acid and linolenic acid. Linoleic acid content of total and neutral lipid was $61{\sim}65%$ palmitic acid content in phospholipid was $26{\sim}39%$ and one year old root showed the hightest contents. The fatty acid composition of neutral lipid was similar to the pattern of total lipid. Linolenic acid content of glycolipid decreased gradually. Free sugars were composed of rhamnose, fructose, glucose, sucrose, maltose and an unidentified material. The content of sucrose was $92{\sim}94%$ of total free sugars. Two year old root showed the highest sugar content and it decreased since then.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.1
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• pp.37-40
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• 1993

This study was conducted to measure the improvement in nutritive value of rice straw by treatment with urine of goat under different temperatures. Straw samples were japonica I (comprising 15 varieties with culms longer than 123 cm and mean silica content of 13.0%), japonica II (comprising 20 varieties with culms less than 87 cm and mean silica content of 13.7%), indica I (Java 14 variety with a high content of silica of 13.9%) and indica II (comprising IR-8 and IR-20 varieties with a low content of silica of 11.0%). Urine was collected from four Japanese Saanen goats fed alfalfa hay. The different straws were sprayed with urine at the rate of 1 ml/g straw DM, put in double layer plastic bags, sealing and stored for 4 weeks at either $20^{\circ}C$ (GU-20) or $40^{\circ}C$ (GU-40). The in vitro dry matter digestibility (IVDMD) and organic matter digestibility (IVOMD) of the straws were improved by the GU-40 treatment (13.5% and 13.2%, but the GU-20 treatment had little effect of digestibility (1.5% and -0.2%) except with the low silica indica II varieties. The GU-40 treatment tended to decrease NDF and hemicellulose content of straws. Crude protein content of the straws was improved by both the GU-20 and GU-40 treatments. It was concluded that treatment of rice straw with goat urine at $40^{\circ}C$ for 4 weeks improved the crude protein content and digestibility in vitro, the greatest improvement occurring with straws of lowest digestibility in the untreated state.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.324-326
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• 2016

In this study, we have investigated indium tin zinc oxide (ITZO) as an active channel for non-volatile memory (NVM) devices. The electrical and memory characteristics of NVM devices using multi-stack gate insulator SiO2/SiOx/SiOxNy (OOxOy) with Si-rich SiOx for charge storage layer were also reported. The transmittance of ITZO films reached over 85%. Besides, ITZO-based NVM devices showed good electrical properties such as high field effect mobility of 25.8 cm2/V.s, low threshold voltage of 0.75 V, low subthreshold slope of 0.23 V/dec and high on-off current ratio of $1.25{\times}107$. The transmission Fourier Transform Infrared spectroscopy of SiOx charge storage layer with the richest silicon content showed an assignment at peaks around 2000-2300 cm-1. It indicates that many silicon phases and defect sources exist in the matrix of the SiOx films. In addition, the characteristics of NVM device showed a retention exceeding 97% of threshold voltage shift after 104 s and greater than 94% after 10 years with low operating voltage of +11 V at only 1 ms programming duration time. Therefore, the NVM fabricated by high transparent ITZO active layer and OOxOy memory stack has been applied for the flexible memory system.

• Korean Journal of Materials Research
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• v.14 no.9
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• pp.676-681
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• 2004

In-situ observation in SBM on the microfracture behavior of coating layer was performed for GA steel sheets that have various Fe contents and thickness of coating layer. In case of cross sectional side of coating layer that was in a tensile stress state during bending, fine perpendicular crack pre-induced during galvannealing grew and propagated rapidly toward the coating surface with the increase of strain. And then it grew and propagated along the ${\Gamma}/Fe$ matrix interface, and combined with the nearest another perpendicular crack. Consequently, flaking occurred. The more Fe content and thickness of coating layer increased, the more average crack interval and flaking resistivity increased. Exfoliation was little observed at coating surface in a tensile stress state.