• The Korean Journal of Ceramics
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• 제5권3호
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• pp.217-223
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• 1999

Proten-conductive $SrZr_{0.95} Y_{0.05} O_{2.975}$ powder was prepared by citrate gel method its characteristics and sinterability were investigated. Amorphous gel could be obtained from a citric acid solution that $SrCO_3$ and metal nitrates were dissolved. The initial decomposition of the gel proceeded up to $250^{\circ}C$, followed by combustion of its decomposition products in the temperature range from $250^{\circ}C$ to $500^{\circ}C$. A well-crystallized perovskite phase with a stoichiometric composition after calcination at $1000^{\circ}C$. Sintering green compacts of this powder for 6 h showed a considerable densification to start at $1200^{\circ}C$ and resulted in 86.8% and 96.5% relative densities at $1400^{\circ}C$ and $1600^{\circ}C$, respectively. Whereas, the powder compacts prepared by solid state reaction had much lower relative densities, 73% at $1400^{\circ}C$ and 92% at $1600^{\circ}C$.

• The Korean Journal of Ceramics
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• 제6권1호
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• pp.58-63
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• 2000

The preparation of Y-doped $SrZrO_3$powder by ultrasonic spray pyrolysis was investigated as a representative system, in order to produce fine, single phase multicomponent oxide powders. A precursor solution containing metal nitrates, citric acid and ethylene glycol was atomized glycol was atomized with an ultrasonic spray nozzle. Gel particles formed by organic functional groups were pyrolyzed and subsequently calcined at $800^{\circ}C$ to obtain well-crystallized, single perovskite phase. Most of large particles exhibited macroscopic pores and weak agglomeration between primary particles. However, strong agglomeration was observed in the surfaces of large particles. The effect of the microstructures of these particles on size reduction to submicron particles was described.

• 한국환경과학회지
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• 제26권5호
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• pp.685-689
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• 2017

Aquatic plants serve the crucial function of helping to balance water reservoir ecosystem, as they filter and remove major minerals required for algal growth such as nitrogen, ammonia, and nitrates. Aquatic plants provide food, shade, and protection for the aquatic biome in and around the reservoir. Thus, it is important to accurately determine the existence and areal extent of the aquatic plants. In the present study drone-based facilities were used for this purpose. In the Muncheon water reservoir, Gyeongbuk, the Normalized Difference Vegetation Index (NDVI) and Surface Algal Bloom Index (SABI) were used to determine the existence status of the aquatic plants. The data so obtained exhibited reasonable accuracy; drone-based facilities can be used in future to identify the areal extent of aquatic plants.

• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.711-714
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• 2004

Peroxynitrite enters erythrocytes through band 3 anion exchanger and oxidizes cytosolic proteins therein. As a protein associated with band 3, carbonic anhydrase II may suffer from peroxynitrite-induced oxidative damages. Esterase activity of carbonic anhydrase II decreased as the concentration of peroxynitrite increased. Neither hydrogen peroxide nor hypochlorite affected the enzyme activity. Inactivation of the enzyme was in parallel with the release of zinc ion, which is a component of the enzyme's active site. SDS-PAGE of peroxynitrite-treated samples showed no indication of fragmentation but non-denaturing PAGE exhibited new bands with lower positive charges. Western analysis demonstrated that nitration of tyrosine residues increased with the peroxynitrite concentration but the sites of nitration could not be determined. Instead MALDI-TOF analysis identified tryptophan-245 as a site of nitration. Such modification of tryptophan residues is responsible for the decrease in tryptophan fluorescence. These results demonstrate that peroxynitrite nitrates tyrosine and tryptophan residues of carbonic anhydrase II without causing fragmentation or dimerization. The peroxynitrite-induced inactivation of the enzyme is primarily due to the release of zinc ion in the enzyme's active site.

• Progress in Superconductivity
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• 제6권2호
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• pp.124-128
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• 2005

Homogeneous and fine powders for Bi-2223 tape were prepared by ultrasonic spray pyrolysis (SP) method from an aqueous solution of metal nitrates. Bi-2223 precursor powders were synthesized with various solutes concentration and pyrolysis temperature. The synthesized precursor powders had a narrow particle size distribution and an average particle size was $\~{\cal}um$. The reactivity of precursor powder by SP method is very high, attributed to the fine and narrow particle size distribution. Bi-2223/Ag tape was prepared using PIT method and followed by various sintering conditions. The precursor powder by SP method promoted a very quick formation of the Bi-2223 phase for short sintering time while the secondary phase such as large AEC phase and $Ca_2PbO_4$ were minimized for SP tapes.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2002년도 추계국제학술대회
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• pp.125-134
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• 2002

Crop Protection Products (CPPs) are a useful weapon in our fight against the pests, diseases and weeds that harm or destroy our food. To be effective CPPs need to exhibit some persistence. The consequence of this is that residues of the original material or its metabolites may remain on food and thus there is a potential for the intake of such residues. The issue of CPP residues in food is an emotional subject and is rarely debated rationally or supported by scientific facts. Media headlines like “Poison in our food” or “These days enough Pesticides (CPPs) are sprayed onto vegetables to turn you into one” are testimony to the high level of emotion that surrounds the subject of CPP residues in food. Recent surveys of consumers have indicated that more than 80 percent view CPP residues in food as a “serious hazard”. This significantly exceeds concerns over drugs, hormones in meat, nitrates in food, irradiated foods, food additives, or artificial colours.

• 한국해양학회지
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• 제19권1호
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• pp.89-93
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• 1984

진해만에서 83년 7월의 장마직후에 수직적 및 수평적 해양화학적 환경을 조사 하였다. 마산만-가덕수도의 종축면상에는 염분이 낮은 내만쪽의 표층수에서 높은 농도의 용존성 질산염, 암모니아, 클로로필 a, 입자성질소, 입자성탄소가 측정 되었다. 입자성 C/N비는 내만쪽에서 낮고, 외만에서 높은 값을 보였다. 이 해역 에서 무기질소와 인의 양은 적조가 발생하기에 충분한 향으로 나타났다.

• 대한임상검사과학회지
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• 제36권1호
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• pp.7-12
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• 2004

Trichophyton(T.) tonsurans has been identified for the first time in Korea in 1995 and has been increasing in number of reported in wrestlers, in judo players, and in korean - style wrestlers. Author tried mycological studies with T. tonsurans is isolated in Daegu Korea. The results are as follows: All 16 strains of T. tonsurans tested for nutritional requirement, showed strongly stimulated growth by thiamine, mild to moderate growth on casamino acid agar, poor growth on ammonium nitrates base agar. All 16 strains of T. tonsurans tested showed positive results for hair perforation and urease test. Gross findings of T. tonsurans showed that fine granular surface with light yellow hue or white color and mahogany brown color on the reverse side. Microscopic findings showed that septated hyphae, chlamydoconidia and microcondia. Microconidia were characteristic in their arrangerment and shape : round or oval shaped microconidia laterally to hyphae, some were match - head like terminal swelling.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.581-584
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• 2002

A new method for the preparation of lanthanide ions activated strontium aluminates phosphor by combustion method has been proposed. Combustion method consist of the redox reactions between the respective metal nitrates and urea in a preheated funace at $500^{\circ}C$. The luminescence behavior of the phosphor was studied and compared with corresponding phosphor prepared by conventional method. Effect of $Mg^{2+}$ ion concentration in strontium aluminate phosphor was investigated and the maximum luminescence of about $100cd/m^2$ was obtained. This method gave better brightness and small size to the phosphor than made by conventional method.

• 한국세라믹학회지
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• 제38권11호
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• pp.959-961
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• 2001

Nanosized CeO$_2$Powders were prepared under high temperature and pressure conditions by precipitation from metal nitrates with aqueous potassium hydroxide. Spherical shape of CeO$_2$powder was obtained at 175$^{\circ}C$ for 6h. TEM and X-ray diffraction patterns showed that the synthesized particle was crystalline. The average size and size distribution of the synthesized particles were below 30 nm and narrow, respectively. In addition, the effects of synthesis parameters under hydrothermal process are discussed.