• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.816-817
• /
• 2006

Hydrogen, in even small quantities, is extremely deleterious to the sintering of aluminium. Understanding the cause of this effect is complicated by the multiple interactions that occur in multi-component systems. In this work, we examine the sintering rsponse of Al-2Mg (a simplified system) in pure nitrogen and nitrogen-hydrogen using dilatometry, differential scanning calorimetery, thermogravimetry and metallography.

• The Korean Journal of Food And Nutrition
• /
• v.24 no.3
• /
• pp.367-375
• /
• 2011

For this study, Korean-type Koumiss was made by the fermentation of mixed cultures, in which yeast, Kuyveromyces, and microflora, Streptococcus thermophiles and Lactobacillus bulgaricus, were inoculated into 10% skimmed milk with added whey powder(control: A, 2%: B, 4%: C, 6%: D, and 8%: E). Fat, protein, lactose, titratable acidity, pH, the number of lactic acid bacteria, the number of yeast, alcohol content, volatile fatty acids, volatile free amino acids and minerals were measured in the products. The results were as follows: As the dosage of whey powder increased, fat increased from 0.74% in the control to 2.30% in sample E, protein increased from 2.95% in the control to 4.39% in sample E and lactose increased from 3.10% in the control to 7.43% in sample E. Titratable acidity and pH increased gradually. The number of lactic acid bacteria increased from $10^9\;cfu/m{\ell}$ in the control to $3.8{\times}10^9\;cfu/m{\ell}$ in sample E, and the number of yeast increased from $6.1{\times}10^7\;cfu/m{\ell}$ in the control to $1.65{\times}10^8\;cfu/m{\ell}$ in sample E, according to the increase of whey powder content. For alcohol content, the average values were 0.863%, 0.967%, 0.890%, 1.290%, and 1.313% for the control and samples B, C, D, and E, respectively. As the dosage of whey powder increased, alcohol content showed a tendency to gradually increase. The average alcohol content of E was 1.313 and this was higher than the alcohol content of Kazahstana-type Koumiss with 1.08%. Sixteen types of free amino acids were detected. Glycine was the lowest in the control at $0.38mg/m{\ell}$ and sample E contained $0.64mg/m{\ell}$. Histidine was also low in the control at $0.42mg/m{\ell}$ and sample E contained $0.65mg/m{\ell}$. On the other hand, glutamic acid was highest at $4.13mg/m{\ell}$ in the control whereas sample E had $6.96mg/m{\ell}$. Proline was also high in the control at $1.71mg/m{\ell}$ in control, but E contained $2.80mg/m{\ell}$. Aspartic acid and leucine were greater in sample E than in the control. For volatile free fatty acids, content generally had a tendency to increase in the control, and samples B, C, D, and E. Content of acetic acid gradually increased from $12,661{\mu}g/100m{\ell}$ in the control to $37,140{\mu}g/m{\ell}$ in sample E. Butyric acid was not detected in the control and was measured as $1,950{\mu}g/100m{\ell}$ in sample E. Caproic acid content was $177{\mu}g/100m{\ell}$ in the control and $812{\mu}g/100m{\ell}$ in sample E, and it increased according to the increase of whey powder content. Valeric acid was measured in a small amount in the control as $22{\mu}g/100m{\ell}$, but it was not detected in any other case. Mineral contents of Ca, P, and Mg increased from 1,042.38 ppm, 863.61 ppm, and 101.28 ppm in the control to 1,535.12 ppm, 1,336.71 ppm, and 162.44 ppm in sample E, respectively. Na content was increased from 447.19 ppm in the control to 1,001.57 ppm in sample E. The content of K was increased from 1,266.39 ppm in the control to 2,613.93 ppm in E. Mineral content also increased with whey powder content. In sensory evaluations, the scores increased as whey powder content increased. Flavor was lowest in the control with 6.3 points and highest in E with 8.2 points. Body and texture were highest at 4.2 points in the control, which did not have added whey powder. In the case of appearance, there were no great differences among the samples.

• Progress in Superconductivity and Cryogenics
• /
• v.16 no.1
• /
• pp.9-13
• /
• 2014

Effects of neutron irradiation on the superconducting properties of the undoped $MgB_2$ and the carbon(C)-doped $MgB_2$ bulk superconductors, prepared by an in situ reaction process using Mg and B powder, were investigated. The prepared $MgB_2$ samples were neutron-irradiated at the neutron fluence of $10^{16}-10^{18}n/cm^2$ in a Hanaro nuclear reactor of KAERI involving both fast and thermal neutron. The magnetic moment-temperature (M-T) and magnetization-magnetic field (M-H) curves before/after irradiation were obtained using magnetic property measurement system (MPMS). The superconducting critical temperature ($T_c$) and transition width were estimated from the M-T curves and critical current density ($J_c$) was estimated from the M-H curves using a Bean's critical model. The $T_cs$ of the undoped $MgB_2$ and C-doped $MgB_2$ before irradiation were 36.9-37.0 K and 36.6-36.8 K, respectively. The $T_cs$ decreased to 33.2 K and 31.6 K, respectively after irradiation at neutron fluence of $7.16{\times}10^{17}n/cm^2$, and decreased to 22.6 K and 24.0 K, respectively, at $3.13{\times}10^{18}n/cm^2$. The $J_c$ cross-over was observed at the high magnetic field of 5.2 T for the undoped $MgB_2$ irradiated at $7.16{\times}10^{17}n/cm^2$. The $T_c$ and $J_c$ variation after the neutron irradiation at various neutron fluences were explained in terms of the defect formation in the superconducting matrix by neutron irradiation.

• 한국초전도학회:학술대회논문집
• /
• 2007.07a
• /
• pp.69-69
• /
• 2007

• 한국초전도학회:학술대회논문집
• /
• 2009.07a
• /
• pp.105-105
• /
• 2009

• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.18-19
• /
• 2006

In this study, dielectric properties of the ${Mg_5}{B_4}{O_{15}}$ (B=Ta, Nb) cation-deficient perovskite ceramics and its oscillator application are investigated. The cation-deficient perovskite ceramics are prepared through the solid-state route. According to the XRD pattern, ${Mg_4}{Ta_2}{O_9}$ and $Mg{Ta_2}{O_6}$ phase existed in calcined and sintered ${Mg_5}{Ta_4}{O_15}$ powder. Also ${Mg_5}{Ta_4}{O_{15}}$ phase added with increasing sintering temperature. In the case of calcined and sintered ${Mg_5}{Nb_4}{O_{15}}$ powder, single phase of ${Mg_5}{Nb_4}{O_{15}}$ is appeared. In the case of the ${Mg_5}{Ta_4}{O_{15}}$ and ${Mg_5}{Nb_4}{O_{15}}$ ceramics sintered at $1450^{\circ}C$ for 5h, the dielectric constant, quality factor, and temperature coefficient of the resonant frequency (TCRF) were 8.2, 259,473 GHz, $-10.91ppm/^{\circ}C$ and 14, 37,350 GHz, $-52.3\;ppm/^{\circ}C$, respectively. Simulated DR with ${Mg_5}{Ta_4}{O_{15}}$ ceramics had the operating frequency of 10.99 GHz and S(2,1) of -29.795 dB. Size of manufactured oscillator was $56{\times}48{\times}34\;mm^3 and operated at 11.93 GHz. Power output and second harmonic of oscillator were +13.61 dBm and -23.81 dBc at 23.85 GHz, respectively.

• Progress in Superconductivity and Cryogenics
• /
• v.7 no.1
• /
• pp.1-4
• /
• 2005

Nano- sized spherical $MgB_2$ Powders were synthesized by spray Pyrolysis method. The Influence of solution concentration and furnace reaction temperature on morphology and average particle size were investigated. For adequate preparation conditions, it has mostly spherical, solid and narrow particle size distribution. Average particle size$(X_{50})$ distribution was below 100 nm. The critical temperature for the synthesized $MgB_2$ was around 36K.

• Korean Journal of Food Science and Technology
• /
• v.38 no.4
• /
• pp.513-520
• /
• 2006

Spray-dried (SD) and freeze-dried (FD) takju powders were stored at 5, 15 and $25^{\circ}C$, and various quality characteristics such as moisture, amino nitrogen, color value, total viable cell count, total sugar, reducing sugar organic acid, and flavor compounds were measured for 50 days at 10-day intervals. After 50 days of storage, the moisture content was increased from an initial 6.64% to 7.24-7.38% in the SD powder, and from an initial 4.86 to 5.43-5.61% in the FD powder. pH, total acid content and total viable cell counts were slightly increased. Organic acid content was decreased in the SD powder from an initial 3,949.9 mg% to 805.9-922.3 mg%, and in the FD powder from an initial 5,171.5 mg% to 3,646.0-4,110.2 mg%. Amino nitrogen content was increased in the SD powder from an initial 1.2% to 1.9-2.2% and in the FD powder from an initial 1.9% to 2.2-2.5%. Total sugar and reducing sugar contents were increased in the SD powder from an initial 17.2% and 4.0% to 25.9-27.3% and 5.8-6.9%, and in the FD powder from an initial 19.1% and 5.2% to 29.2-30.2% and 8.3-8.8%, respectively. With increasing storage time, L and b values in the SD powder increased slowly, while L value in the FD powder tended to decrease and b value tended to increase. About 20 major volatile flavor components were identified in the SD and FD powders by GC-MS and all such component levels were decreased with increasing storage time.

• Journal of Plant Biotechnology
• /
• v.48 no.2
• /
• pp.77-85
• /
• 2021

Hydroponic cultivation, in which crops are grown without soil and are unaffected by the weather, has many advantages over conventional soil cultivation. The crop's growth can be further accelerated by using nutrient solution in place of water. This study investigated the growth and physicochemical properties of hydroponic barley sprouts under various nutrient solution and artificial light treatments. The shoot, root, and total plant length increased over time, with the fastest growth occurring in the nutrient solution and light-emitting diode (LED) treatments. Fresh and dry plant weights were higher in the fluorescent lamp treatment than in the LED treatment. Barley sprout powder color differed slightly by treatment, with the Hunters L value ranging from 50.79 to 53.77; Hunters a value from -6.70 to -4.42; and Hunters b value from 13.35 to 14.76. The Hunters L and Hunters b values were highest in the LED treatment, whereas the Hunters a value was relatively highest in the fluorescent lamp treatment. The total phenol content was higher in the control than in the nutrient solution treatment; however, the total flavonoid content showed the opposite pattern to that of total phenol content, being highest in plants that were grown in nutrient solution. The Trolox equivalent antioxidant capacity (TEAC) was higher in the control group than in the nutrient solution group. The ferric ion reducing antioxidant power (FRAP) was higher in the fluorescent treatment group than in the LED treatment group. The total amino acid composition ranged from 106.82 to 122.63 mg/g dry powder, with the essential amino acid composition ranging from 47.01 to 56.19 mg/g, and non-essential amino acid composition from 67.86 to 77.66 mg/g. The most frequently detected compositional amino acid was aspartic acid, followed by glutamic acid, alanine, leucine, and valine.

• Journal of the Korean Ceramic Society
• /
• v.46 no.1
• /
• pp.53-57
• /
• 2009

The h-BN powder was synthesized by amorphous $B_2O_3$ and activated carbon at $1550^{\circ}C$ in nitrogen atmosphere, whose properties were examined according to $MgB_6$ addition. Amount of $MgB_6$ addition was varied in the range of $0{\sim}$10\;wt% of the initial mixture. It was observed that $MgB_6$ addition led to an increase in the amount and the grain size of h-BN and decrease in the amount of $B_4C$ forming. When $MgB_6$ added 5 wt%, the amount and crystallinity of h-BN increased as the holding time at the synthesis temperature was prolonged. It was also confirmed that the regularity of three-dimensional ordering of h-BN increases.