• Korean Journal of Veterinary Research
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• v.48 no.2
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• pp.145-151
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• 2008

This study was conducted to investigate biochemical properties and O group serotypes of pathogenic 203 Escherichia (E.) coli isolates from poultry with collibacillosis in Korea during the period from April 2003 to December 2005. Biochemical and fermentative properties of 203 isolates of E. coli tested were in accordance with Cowan and Steel's classification standard. One hundred and forty one isolates (69.5%) could be classified into a total of 20 O serotypes. Among them, the predominant O groups were O78 (32.5%), O88 (7.8%), O15 (6.8%), O141 (6.4%), and O158 (3.0%) in decreased order. Other infrequently encountered serogroups included : O8 (2%), O161 (2%), O20 (1.5%), O125 (1.5%), O2 (1%). And O6, O18, O24, O46, O76, O109, O119, O138, O139 and O148 had a frequency of 0.5%, respectively. Sixty two isolates (30.5%) were non-typeable with standard 173 O antisera used in this study.

• Journal of the Korean Ceramic Society
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• v.31 no.6
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• pp.629-636
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• 1994

The ferrimagnetic glass-ceramics in the system Fe2O3-CaO-SiO2 for hyperthermia were investigated. Glasses could be prepared up to the content of 40 wt% of Fe2O3 and below the weight ratio of 1.0 of CaO/SiO2. The maximum saturation magnetization and the maximum coercive force were 29.85 emu/g and 340.1 Oe respectively, for a glass 40Fe2O3.20CaO.40SiO2 composition heat-treated at 95$0^{\circ}C$ for 8 hours. And for a glass 40Fe2O3.30CaO.30SiO2 composition the maximum saturation magnetization and the maximum coercive force were 18.47 emu/g and 374.4 Oe heat-treated at 1,00$0^{\circ}C$ and 90$0^{\circ}C$ for 8 hours respectively. The maximum hysteresis loss was 1,726.3 cal/g for a glass 40Fe2O3.20CaO.40SiO2 composition heat-treated at 95$0^{\circ}C$ for 8 hours. It was found that the ferrimagnetic Fe2O3.CaO.SiO2 glass-ceramics was little injurious to human body as results of biocompatibility test and biotoxicity test.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.78-86
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• 2017

As the amount of slag generated annually increases, attempts to recycle slag as high value products are underway in order to develop an efficient resource recycling industry based on slag and derive economic benefits as well. However, the application of electric arc furnace (EOS) slag as construction material is practically limited because of the unstable substances included in it, such as free CaO.(EOS contains a small amount of free CaO, but several limitations still exist. Slag is stored for more than 3 months depending on the quantity of slag, which leads to additional economic loss. In this study, the amount of free CaO present in EOS is quantitatively evaluated to examine its qualities as a potential construction material and verify its application as concrete material. The quantitative analysis of free CaO present in EOS is performed using ethylene glycol. The free CaO contents of EOS samples were found to be below 0.5%. This satisfies the criteria specified in KS F 4571, which states that the CaO content should be below 40% and $CaO/SiO_2$ ratio should be below 2.0. In addition, it was confirmed that free CaO content difference appears to be dependent on the aging period and storage position.

• 보존과학연구
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• s.35
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• pp.5-23
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• 2014

The possibility of non-destructive inspection glass beads for verification. Conduct a comparative analysis of the Chungcheong area with glass beads excavated Age-specific characteristics of the glass beads shall be classified by region. Trace amounts of ingredients such as CaO, $Al_2O_3$ (stabilizer), MgO, the difference is negligible. $SiO_2$ (subjects), $Na_2O$ (flux) analysis and the difference between the values was greater than in the other ingredients. Composition differences occurred rough surface to a non-uniform cross-section analysis is considered. Minimize the error value, such as the surface of carbon-coated Study, there are additional requirements. Produced at the time of the social and cultural characteristics of ancient glass and important archaeological materials, and to inform the process of cultural exchange between each region in the production of glass technology era according to the level of science and technology, arts and crafts, can be identified.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.1
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• pp.19-24
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• 1999

$In_2O_3$-based thick films for the ozone detection of ppb range have been investigated. The $In_2O_3$ sensing layer is quite sensitive to ozone, but the saturated stable sensitivity cannot be obtained at the ozone exposure of 100 ppb for 5 min. The addition of $Fe_2O_3$ into $In_2O_3$ indicates some improvement in response time and sensitivity, but it seems the improvement is not good enough for real applications. Firing of $In_2O_3$:$Fe_2O_3$ powder induces remarkable improvement in response and recovery, although the sensitivity decrease. The sensing layer fired at $1300^{\circ}C$ and operated $550^{\circ}C$ shows excellent properties of fast response time, saturated stable sensitivity and rapid recovery characteristics to 100 ppb ozone exposure for 5 min. Especially, it shows the reproducibility of the sensor signal for repeated measurements and the linearity between the ozone concentration and the sensor resistance. The preliminary results clearly demonstrated that the sensor can be successfully applied for the ozone detection of ppb range.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.8
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• pp.616-619
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• 2012

Oxides possess several interesting properties, such as ferroelectricity, magnetism, superconductivity, and multiferroic behavior, which can effectively be used oxide electronics based on epitaxially grown heterostructures. The microscopic properties of oxide interfaces may have a strong impact on the electrical transport properties of these heterostructures. It was recently demonstrated that high electrical conductivity and mobility can be achieved in the system of an ultrathin $LaAlO_3$ film deposited on a $TiO_2$-terminated $SrTiO_3$ substrate, which was a remarkable result because the conducting layer was at the interface between two insulators. In this study, we observe that the current-voltage characteristics exhibit $LaAlO_3$ thickness dependence of electrical conductivity in $TiO_2$-terminated $SrTiO_3$. We find that the $LaAlO_3$ layers with a thickness of up 3 unit cells, result in highly insulating interfaces, whereas those with thickness of 4 unit cells and above result in conducting interfaces.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.6
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• pp.749-758
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• 2004

Nitrous oxide ($N_2$O) has been known as an important trace gas due to the greenhouse gas and the major source of stratospheric oxide of nitrogen (NO). Soil is the major source of $N_2$O in nature. The physicochemical characteristics of soils affect the emission of $N_2$O from soil. These physicochemical parameters are soil moisture, soil temperature, and soil N content. Since these parameters are correlated to the flux of $N_2$O from soil individually and compositely, there still remain many unknowns in the mechanism to produce $N_2$O in soil and the roles of such physicochemical parameters which affect the soil $N_2$O emission. Soil $N_2$O fluxes were measured at different levels in water filled pore space (WFPS), soil temperature and soil N contents from the same amounts of soils which were sampled from agriculturally managed upland field in a depth of ～30 cm at Kunsan. The soil $N_2$O flux measurements were conducted in a laboratory with a closed flux chamber system. The optimum soil moisture and soil temperature were observed at 60% of WFPS and ～13$^{\circ}C$. The soil $N_2$O flux increased as soil N contents increases during the whole experimental hours (up to 48 hours). However, average $N_2$O flux decreased after ～30 hours when organic carbon was mixed with nitrogen in the sample soils. It is suggested that organic carbon could be important for the emission of $N_2$O, and that the ratio of N to C needs to be identified in the process of $N_2$O soil emission.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.2
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• pp.121-126
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• 1996

To investigate the effects of potassium($K_2O$) fertilization levels on the dry matter(DM) yield, nutrition yield, and $K_2O$ efficiency of forages in mixed sward of alfalfa-grasses, a field experiment arranged by randomized complete block design with five treatments(0, 60, 120, 180 and 240kg $K_2O$/ha) was conducted at National Livestock Research Institute in Suwon, September, 1990 to February, 1993. During two years, average DM yields of forage increased as $K_2O$ fertilization level was increased, but no significant difference was found between DM 10,617kg of $K_2O$180kgha and DM 10,845kg of $K_2O$ 240kg/ha. Crude protein and energy productivity of forages increased as $K_2O$ fertilization level was increased, and the increasing degree was highest between $K_2O$ 120kg and 180kg/ha fertilization. With increasing $K_2O$ fertilization, mineral contents tended to increase in K and WCa+Mg equivalent ratios, to decrease in Mg, but not to be regular in the other elements. Efficiency of $K_2O$ was relatively high at $K_2O$ 180kgha fertilization, which produced DM 12.2kg, net energy lactation 67.3M.J, starch equivalent 6.2kStE and total digestible nutrients 7.6kg per Ikg $K_2O$. Therefore, potassium($K_2O$) fertilization levels must be applied with I8Okg/ha for a reasonable management in mixed sward of alfalfa-grasses.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.975-978
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• 2003

The microwave dielectric properties and the microstructures on B $i_{0.97}$T $m_{0.03}$Nb $O_4$ doped with $V_2$ $O_{5}$ were systematically investigated. B $i_{0.97}$T $m_{0.03}$Nb $O_4$ ceramics sintered at 920-96$0^{\circ}C$ were mainly consisted of orthorhombic and triclinic phases after addition of $V_2$ $O_{5}$. The apparent density increased slightly with increasing the $V_2$ $O_{5}$ addition. The dielectric constants($\varepsilon$$_{r}$) also increased with $V_2$ $O_{5}$ addition(30-45). The Q${\times}$ $f_{0}$ values measured on B $i_{0.97}$T $m_{0.03}$Nb $O_4$ ceramics doped with $V_2$ $O_{5}$ were between 2,000 and 12,000[GHz] when the sintering temperatures were in the range of 920-960[$^{\circ}C$]. It was confirmed that the temperature coefficient of the resonant frequency($\tau$$_{f}$) can be adjusted from a positive value of +10ppm/$^{\circ}C$ to a negative value of -15ppm/$^{\circ}C$ by increasing the amount of $V_2$ $O_{5}$ Based on our experimental results, the B $i_{0.97}$T $m_{0.03}$Nb $O_4$(added $V_2$ $O_{5}$) ceramics can be applied to multilayer microwave devices at low sintering temperatures.ng temperatures.emperatures.ratures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.350-353
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• 2002

The microwave dielectric properties and the microstructures on $Bi_{0.97}Nb_{0.03}O_{4}$doped with $V_{2}O_{5}$ were systematically investigated. $Bi_{0.97}Tm_{0.03}Nb_{0.03}O_{4}$ ceramics sintered at $920-960^{\circ}C$were mainly consisted of orthorhombic and triclinic phases after addition of $V_{2}O_{5}$. The apparent density increased slightly with increasing the $V_{2}O_{5}$ addition. The dielectric $constants(\varepsilon_r)$ also increased with $V_{2}O_{5}$ addition(30-45). The $Q{\times}f_0$ values measured on $Bi_{0.97}Tm_{0.03}NbO_4$ ceramics doped with $V_{2}O_{5}$ were between 2,000 and 12,000[GHz] when the sintering temperatures are in the range of $920-960[^{\circ}C]$. It was confirmed the temperature coefficient of the resonant $frequency(\tau_f)$ can be adjusted from a positive value of $+10[ppm/^{\circ}C]$ to a negative value of $-15ppm/^{\circ}C$ by increasing the amount of $V_{2}O_{5}$. Based on our experimental results, the Bi0.97Tm0.03NbO4(added V2O5) ceramics can be applied to multilayer microwave devices at low sintering temperatures.