• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.50.1-50.1
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• 2011

Lead-free ceramics with a composition of 0.55 mol%$K_4CuNb_8O_23-(K_{1-x}Na_x)NbO_3$ (KCN-KNNx) where $0.45{\leq}x{\leq}0.60$ were synthesized by conventional ceramic processing. Results revealed that the addition of Na was effective in changing the microstructure and relative density of KCN-KNNx. Further, the addition of Na resulted in a slight shift of the phase transition temperatures (To-t and Tc) toward low values. A high mechanical quality factor (Qm) of 1850 was found atx=0.54, which might be due to the build-up of an internal bias field (Ei) within KCN. Thermal hysteresis in KNNx was confirmed with an increase in the Na content during the heating and cooling cycles, resulting from structural changes. Thus, KCN-KNNx with x=0.54 exhibits excellent piezoelectric properties with d33 (97 pC/N), kp (36%), and Qm (1850), being promising candidates for application in high-power piezoelectric devices.

• Progress in Superconductivity
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• v.3 no.2
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• pp.198-212
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• 2002

The effects of reacted precursors on phase evolution, microstructure, $J_{c}$ and junctional characteristic of the inter-granular contacts were investigated in Ag-sheathed T1-1223 tapes prepared using three kinds of reacted precursors, and compared to those in the tape prepared using an unreacted precursor The precursors were prepared by heat-treating a mixture of Sr-Ba-Ca-Cu-O, $Tl_2$$O_3$, PbO and $Bi_2$$O_3$ powders at $805^{\circ}C$ (precursor I ), $840^{\circ}C$ (precursor II ) and $905^{\circ}C$(precursor III) for 20 min. Tl-1223 phase content, grain size and J\ulcorner in the tapes appeared to increase in an order of precursors I, II and III Compared to tapes prepared using an unreacted precursor, the tapes prewar ed using precursors II and III revealed reduced pore and impurity densities and an enhanced texture. Also characteristic of inter -granular contacts and fraction of strong-links were improved. The improved properties are attributed to enhanced densification resulting from using the reacted precursors.s.

• Journal of the Mineralogical Society of Korea
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• v.19 no.3 s.49
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• pp.163-169
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• 2006

Mineralogy and geochemistry of the sediment core from the seamount (2710 m below the sea level) just south of the Antarctic Polar Front were examined to draw paleoceanographic information in glacial-interglacial cycles. Smectite was most abundant clay mineral associated with illite and chlorite. Its content was slightly higher below 170 cm, suggesting a boundary between isotope stage 4 and 5. Si, Zr, Cs, Th, REE, $K_{2}O$, and $Al_{2}O_{3}$ show complete antithetical distribution with respect to $CaCO_{3}$ through the core. $SiO_{2}$ maxima and $CaCO_{3}$ minima at depths of 24, 136, and 176 cm are probably correlated with massive influx of ice-rafted debris during the advance of Antarctic ice shelves. Ni, Cu, and Ba show rather little correlation with $SiO_{2}$, suggesting their relation to biogenic debris, precipitation from seawater, or hydrothermal input. Particularly, Ba maxima tend to lag $10{\sim}20cm$ after $SiO_{2}$ maxima, probably due to rapid increase of productivity following deglaciation.

• Progress in Superconductivity
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• v.7 no.2
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• pp.140-144
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• 2006

We fabricated the YBCO films on single crystal $LaAlO_3$ substrates via a metal organic deposition (MOD) process. In the process, $Y_2Ba_1Cu_1O_x$ and $Ba_3Cu_5O_8$ powders were dissolved in trifluoroacetic acid (TFA) followed by calcining and firing heat treatments. To evaluate the effects of the firing temperature on YBCO phase formation and critical properties, the films were fired at $750^{\circ}C,\;775^{\circ}C\;and\;800^{\circ}C$ after calcining at $430^{\cric}C$. Microstructure observation indicated that a crack-free surface formed and a strong biaxial texture was developed. The FWHM of out-of-plane texture was measured to be in the range of $4.3^{\cric}-7.0^{\circ}$ for all the films. When the YBCO film was fired at $775^{\cric}C$, it had the highest critical properties: 88.5 K of critical temperature and 16 A/cm-width of critical current ($1MA/cm^2$ as critical current density). On the other hand, those properties were degraded as firing at $750^{\circ}C\;and\;800^{\circ}C$. It is considered that the improved critical values are partly owing to dense and homogeneous microstructure, strong texture, and high oxygen content.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.8
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• pp.1066-1072
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• 2010

In this study, the effects of replacing inorganic copper, zinc and manganese with different levels of organic complexes of the same trace minerals on the lipid peroxidation and antioxidant defense systems in broilers were investigated. Two-hundred Ross-308 one-day-old broiler chickens were placed on controlled diets until 42 d of age. The experimental animals were divided into four groups comprising three experimental groups and one control group, each consisting of 50 chickens. All groups were also divided into five subgroups each containing 10 broiler chicks. The mineral content of the control group diet was controlled using a standard inorganic mineral premix with supplement levels and sources of trace minerals typical of commercial broiler diets according to the National Research Council (NRC) (containing 8 mg Cu as $CuSO_4$, 40 mg Zn as $ZnSO_4$, and 60 mg Mn as MnO, per kg). In the experimental diets, mineral premix was also comprised of inorganic formulations, except for those of Cu, Zn and Mn. Organically-complexed Cu, Zn, and Mn were separately added to the basal diet at 1/3 (L1), 2/3 (L2) and 3/3 (L3) levels with respect to the NRC recommendation, as Bioplex $Cu^{TM}$, Bioplex $Zn^{TM}$, Bioplex $Mn^{TM}$. At the end of the trial, the plasma Zn level significantly increased when the plasma Cu level significantly decreased (p<0.05) in chickens fed at 2/3 and 3/3 levels of organically complexed minerals. The liver trace mineral concentrations were significantly higher in chickens fed inorganic trace minerals in comparison to those fed organically-complexed minerals. The plasma malondialdehyde (MDA) level of experimental chickens was decreased in groups receiving levels of organic Cu, Zn and Mn in comparison to those fed inorganic forms (p<0.01). The erythrocyte superoxide dismutase (SOD) activity was higher in all groups receiving the organic mineral supplements in comparison to those fed inorganic forms (p<0.01). No differences were observed on either the erythrocyte catalase (CAT) activity or the plasma ceruloplasmin (Cp) levels, and the liver MDA levels and liver CAT and SOD activities in any of the groups that received the organic supplements of Cu, Zn, and Mn. It was concluded that supplementation of lower levels of organically-complexed copper, zinc, and manganese instead of their inorganic forms in diets had no negative effects on the antioxidant defense system in broilers.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1190-1196
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• 2002

Microwave dielectric properties and multilayer characteristics $(1-x)BiNbO_4-xCaNb_2O_6$ (0${\le}$x${\le}$1.0) ceramics were investigated as a function of $CaNb_2O_6$ content. In the composition range of 0.25${\le}$x${\le}$0.75, the mixture phases of $BiNbO_4$ with stibotantalate structure and $CaNb_2O_6$ with columbite structure were detected and secondary phase or phase transition were not detected. Dielectric constant (K) of $(1-x)BiNbO_4-xCaNb_2O_6$ ceramics was largely dependent on the existing phase and could be estimated by the dielectric mixing rule calculated from maxwell equation. Typically, dielectric constant (K) of 26, quality factor (Qf) of 4300 GHz and Temperature Coefficient of resonant Frequency (TCF) of -18 ppm/${\circ}C$ were obtained for $0.5BiNbO_4-0.5CaNb_2O_6$ specimens with 0.8 wt% $CuV_2O_6$ sintered at 1000${\circ}C$ for 3h. The deviation of X-Y shrinkage and camber value of the multilayers obtained from $0.5BiNbO_4-0.5CaNb_2O_6$ green sheet sintered at 850∼950${\circ}C$ for 20 min. were smaller than those of $BiNbO_4$ multilayers.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.3
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• pp.204-210
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• 2013

This study has focused on the possibility for recycling tailings from the Sangdong tungsten mine (TA) as admixture for concrete. TA has been accumulating for several decades in Sangdong, a region in Korea, and there is a growing demand for alternative uses for this hazardous substance. In particular, the use must be in accordance with the hazardous materials stipulations under the Korean waste control act. This study showed that TA presented pH of 8.0-9.3, 18.7-22.0% of water content, 2.7% of maximum ignition loss. The chemical composition of TA showed minute differences from each depth of sampling that represented approximately 50% of $SiO_2$ and 13% of both $Al_2O_3$ and $Fe_2O_3$. The chemical composition of Cd, Cu, Zn and Pb from mortar incorporating TA showed lower levels of hazardous materials which met the specifications of the waste control act in Korea. The TA mortar also appeared very effective for stabilizing/solidifying heavy metals particularly when used in conjunction with SG.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.721-730
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• 1993

Various catalysts of $Cu_xH_3-{_{2x}}PMo_{12}O_{40}{\cdot}_nH_2O$ with different x-values have been prepared and characterized by thermal analysis, X-ray powder diffraction, infrared spectroscopy, BET surface-area measurement, electron microscopy, and temperature programmed desorption of ammonia. The properties of these catalysts in acrolein oxidation have been investigated in a continuous-flow fixed-bed reactor. The catalysts lost their water of crystallization at about $200^{\circ}C$ and their constitutional water between 300 and $400^{\circ}C$. The Keggin structure of the catalysts was identified by infrared spectroscopy. The decomposition of Keggin anion, $(PMo_{12}O_{40})^{3-}$, was increased with the increase of substituted copper content and identifiable $MoO_3$ and $P_2O_5$ as decomposition products were observed. The conversion of acrolein decreased with the increase of x probably due to the decrease of specific surface area and of total amount of acid sites. But specific reaction rate and selectivity to acrylic acid were maximized at x=1.0, and it showed specific acid site distributions.

• Korean Journal of Environmental Agriculture
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• v.18 no.4
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• pp.321-326
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• 1999

This study was performed to evaluate the quality of produced compost and to analyse the change of a component during the reduction compost according to the input volume. The volume of pilot scale used in this study was about 300㎥. The pile of 2m width, 20m length and 1.2m height was constructed. Woodchip was used as bulking agent to enhance pore volume of composting bay and to control water content of food waste in starting time. Food waste was turned using a mechanical tumer twice a day. The result are as follows : In these cases of input volume of $2m^3$ and $3.5m^3$, temperature of composting pile was maintained over $60^{\circ}C$ and water content was 43.6% and 47.2%, respectively. It was proved that microorganisms activity was maintained high in each input volume. After operation of step 1 and step 2, pH and organic matter in the final compost were 6.2, 6.6 and 84.3%, 79.6%, respectively. Cation concentration such as $K_2O,$ CaO and NaCl was accumulated in the compost during the composting period. NaCl concentration in the final compost was 4.62%, 4.92%, respectively. Hence, If was recommended that this compost should be applied to others expect agricultural area or mixed with a low concentration other compost. In the steps 1, input volume of $2m^3$, heavy metal concentration of Pb, Cu, Cr, Ni. Cd were 37.82㎎/㎏, 56.87㎎/㎏, 9.8㎎/㎏. 22.21㎎/㎏ and 3.69㎎/㎏, and 44.55㎎/㎏, 95.54㎎/㎏, 12.22㎎/㎏, 24.94㎎/㎏, and 3.86㎎/㎏ in the step 2.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.6
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• pp.853-859
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• 2009

Endometriosis becomes the most common cause of pelvic pain and infertility women. The cause of endometriosis has ever been entirely proven. However, an increased use of commercial feminine hygiene products such as tampons and sanitary napkins was considered one of the major affect. Harmful substances in feminine hygiene products was analyzed and evaluated. Samples of commercial products obtained from Korea, Japan, America, Germany, and China were analyzed for six hazardous inorganic elements (chromium, cobalt, nickel, copper, cadmium and lead). In the extractable heavy metals of napkins, Cr, Ni and Cu were found in all of the samples, while Cd was detected only in two samples. In the tampons, Cr, Ni and Cu were found in all of the samples. The presence of Co and Cd was not detected in all samples The concentrations of extractable heavy metals in the tampons were lower than those in the sanitary napkins. The content of extractable heavy metals in the sanitary products was compared with the criteria of the 100 $\ddot{O}KO$ TEX Standard. It was confirmed that the level of heavy metals in the sanitary products posed no serious risk to health, based on the human-ecological criteria defined by the 100 $\ddot{O}KO$ TEX Standard.