• Bulletin of the Korean Chemical Society
• /
• 제32권8호
• /
• pp.2607-2610
• /
• 2011

Monodispersed Ag/$TiO_2$ core/shell nanoparticles were synthesized in solution via colloid-seeded deposition process using Ag nanoparticles as colloid seeds and $Ti(SO_4)_2$ as Ti-source respectively. Silver nitrate was reduced to Ag nanoparticles with $N_2H_4{\cdot}H_2O$ in the presence of CTAB as stabilizing agent. The titania sols hydrolyzed by the $Ti(SO_4)_2$ solution deposited on the surface of Ag nanoparticles to form the Ag/$TiO_2$ core/shell nanoparticles. Inductively coupled plasma atomic emission spectrometry (ICP-AES) showed low amount of Ag ion leaching from the Ag/$TiO_2$ core/shell nanoparticles. The Ag/$TiO_2$ core/shell nanoparticles indicated excellent antibacterial effects against Escherichia coli and maintained long-term antibacterial property.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2003년도 추계학술발표회
• /
• pp.409-412
• /
• 2003

Total extraction of stream sediments in the Kwangyang mine area shows their significant pollution with most trace metals such as Cr, Co, Fe, Pb, Cu, Ni, Zn and Cd, due to sulfide oxidation in waste dumps. Calculations of enrichment factor shows that Chonam-ri creek sediments are more severely contaminated than Sagok-ri sediments. Using the weak acid (0.1N HCl) extraction and sequential extraction techniques, the transport and sediment-water partitioning of heavy metals in mine drainage were examined for contaminated sediments in the Chonam-ri and Sagok-ri creeks of the Kwangyang Au-Ag mine area. Calculated distribution coefficient (Kd) generally decreases in the order of Pb $\geq$Al > Cu > Mn > Zn > Co > Ni $\geq$ Cd. Sequential extraction of Chonam-ri creek sediments shows that among non-residual fractions the Fe-Mn oxide fraction is most abundant for most of the metals. This indicates that precipitation of Fe hydroxides plays an important role in regulating heavy metal concentrations in water, as shown by field observations.

• Asian-Australasian Journal of Animal Sciences
• /
• 제19권12호
• /
• pp.1685-1690
• /
• 2006

Kenkatha cattle, a draft purpose breed, which can survive in a harsh environment on low quality forage, was explored genetically exploiting FAO-suggested microsatellite markers. The microsatellite genotypes were derived by means of the polymerase chain reaction (PCR) followed by electrophoretic separation in agarose gels. The PCR amplicons were visualized by silver staining. The allelic as well as genotypic frequencies, heterozygosities and gene diversity were estimated using standard techniques. A total of 125 alleles was distinguished by the 21 microsatellite markers investigated. All the microsatellites were highly polymorphic with mean allelic number of 5.95${\pm}$1.9 (ranging from 3-10 per locus). The observed heterozygosity in the population ranged between 0.250 and 0.826 with a mean of 0.540${\pm}$0.171, signifying considerable genetic variation. Bottleneck was examined assuming all three mutation models which showed that the population has not experienced bottleneck in recent past. The population displayed a heterozygote deficit of 21.4%. The study suggests that the breed needs to be conserved by providing purebred animals in the breeding tract.

• 패션비즈니스
• /
• 제11권6호
• /
• pp.139-156
• /
• 2007

The purpose of this study is to analyze the aesthetic characteristics of traditional Korean patterns appearing on fashion collections from 1990 to 2005. Traditional Korean patterns have been used as an important element to express a Korean image since the 1990s. Frequently used patterns included several kinds of geometric patterns, plant patterns(flower, peony, Four Gracious Plants), and Chinese character patterns. Specifically, since the 2000s, animal patterns such as tiger, Chinese phoenix, and giraffe which were not often used, plant patterns such as arabesque, peony, and flower, and a variety of Chinese character patterns appeared. For the expression techniques, while embroidery and printing was often used in the 1990s, they became varied into printing, beading, embroidery, gold and silver leaf, and hand painting after 2000 as a result of designers' active attempts. The aesthetic characteristics of fashion design with its focus on traditional patterns were analyzed. First, Chinese character patterns and phoenix pattern which were mainly used for a court suit, and show the excellence and unique originality of Korean culture. Second, traditional Korean patterns directly and indirectly imply symbolistic significance of lucky sign and illustrate the use of various lucky sign patterns. Third, traditional Korean patterns such as arabesque or peony were expressed by colorful embroidery to add decorative beauty. Finally, traditional Korean patterns reflect a naturalistic worldview and are completed finished as the design.

• 대한세포병리학회지
• /
• 제5권1호
• /
• pp.1-9
• /
• 1994

The cytological and ultrastructural findings of Pneumocystis carinii(PC) obtained from rats by bronchoalveolar lavage (BAL) are described. All developmental forms of the PC organisms were obtained in the lavage fluid. Papanicolaou stain revealed conglomeration of PC as a foamy cast. The cystic walls of PC were well identified on Gomori's methenamine silver stain. Trophozoites and intracystic bodies were stained by Giemsa and Diff-Quik techniques. Some PC organisms were seen within the alveolar macrophages. Ultrastructurally, the cysts were almost circular in shape, and were nearly devoid of surface tubular extensions. The wall of the cyst was composed of an unit membrane, an intermediate electron lucent layer and an external electron dense layer The cysts frequently contained intracystic bodies, so called sporozoites. Occasionally empty or collapsed cysts with no intracystic bodies, and precysts were found. Trophozoites were variable in size and shape with abundant tubular extensions along the single electron dense pellicle. BAL is a useful method for concentrating the various morphologic forms of PC organisms, and is a rapid diagnostic method for PC pneumonia.

• Corrosion Science and Technology
• /
• 제7권3호
• /
• pp.152-157
• /
• 2008

New wrought magnesium alloys have increasingly been developed in recent years for the automotive industry due to their high potential as structural materials for low density and high strength/weight ratio demands. However, their poor mechanical properties and low corrosion resistance have led to a search for new kinds of magnesium alloys with better strength, ductility, and high corrosion resistance. The main objective of this research is to investigate the corrosion behaviour of new magnesium alloys: Mg-Zn-Ag (ZQ), Mg-Zn-Mn-Si (ZSM) and Mg-Zn-Mn-Si-Ca (ZSMX). These ZQ6X, ZSM6X1, and ZSM651+YCa alloys were prepared using hot extrusion. AC, DC polarization and immersion tests were carried out on the extruded rods. Microstructure was examined using optical and electron microscopy (SEM) and EDS. The addition of silver decreased the corrosion resistance. The additions of silicon and calcium also affected the corrosion behaviour. These results can be explained by the effects of alloying elements on the microstructure of Mg-Zn alloys such as grain size and precipitates caused by the change in precipitation and recrystallisation behaviour.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
• /
• pp.702-705
• /
• 1998

To be applied to electrical equipment HTSC tapes have to endure external stress and so on. The critical current density has been shown depending on the mechanical properties, strain and bending stress. AC loss reduction is primary concern in the development of such high-efficiency equipment. AC losses in Bi-2223 silver-sheathed tapes, both single and multi-filamentary, were investigated by means of AC magnetization techniques. The results were compared with the hysteresis loss equation based on Bean model and the eddy current loss equation. The AC loss of the mono-filamentary tape was the hysteresis. On the contrary, the AC loss of the multi-filamentary tape was substantially dominated by the eddy current loss in the Ag matrix.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
• /
• pp.382-385
• /
• 1998

To be applied to electrical equipment HTSC tapes have to endure external stress and so on. The critical current density has been shown depending on the mechanical properties, strain and bending stress. AC loss reduction is primary concern in the development of such high-efficiency equipment. AC losses in Bi-2223 silver-sheathed tapes, both single and multi-filamentary, were investigated by means of AC magnetization techniques. The results were compared with the hysteresis loss equation based on Bean model and the eddy current loss equation. The AC loss of the mono-filamentary tape was the hysteresis. On the contrary, the AC loss of the multi-filamentary tape was substantially dominated by the eddy current loss in the Ag matrix.

• 한국환경과학회지
• /
• 제29권12호
• /
• pp.1171-1184
• /
• 2020

The green synthesis of inorganic nanoparticles (NPs) using biomaterials has garnered considerable attention in recent years because of its eco-friendly, non-toxic, simple, and low-cost nature. In this study, we synthesized NPs of noble metals, such as Ag and Au using an aqueous extract of a marine seaweed, Ecklonia cava. The formation of AgNPs and AuNPs was confirmed by the presence of surface plasmon resonance peaks in UV-Vis absorption spectra at approximately 430 and 530 nm, respectively. Various properties of the NPs were evaluated using characterization techniques, such as dynamic light scattering, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. Phytochemicals in the seaweed extract, such as phlorotannins, acted as both reducing and stabilizing agents for the growth of the NPs. The green-synthesized AgNPs and AuNPs were found to exhibit high catalytic activity for the decomposition of organic dyes, including azo dyes, methylene blue, rhodamine B, and methyl orange.

• 자원환경지질
• /
• 제38권6호
• /
• pp.663-673
• /
• 2005

지화학 자료의 공간적 분포와 금은광산의 공간적 분포사이의 상관관계를 조사하였다. 활용된 자료는 한국자원연구소에서 발간된 지화학도 중 21개 원소에 대한 도면과, 현재까지 파악된 광산의 위치도면 및 1:100만 지질도이다. 지화학도는 250m 등간격의 격자형 화소로 제작된 도면 중 통계분석을 위하여 1km 간격의 자료를 추출하여 분석하였으며, 광산위치의 지화학 자료 역시 250m 간격의 화소에서 추출하여 분석을 수행하였다. 광산과 지화학자료의 공간적인 상관분석은 베이시안 중첩법과 의사결정나무 기법을 활용하였디. 베이시안 통계기법은 각 지화학도에 분포하는 원소의 화소값을 올림차순으로 정열한 후 자료의 개수가 자기 5, 25, 50, 75, 95, $100\%$에 해당하는 등급을 나누어 모든 지화학도를 6개의 등급을 갖는 도면으로 재분류 하였다. 자 등급에 속한 광산의 개수를 대상으로 광산이 발생할 확률이 계산되었으며, 이 확률을 취합하여 최종 사후확률이 계산되었으며, 사후확률로 광산이 배태될 예측 도면이 작성되었다. 금/은, 동, 철, 납/아연, 텅스텐광산 및 광산이 존재하지 않는 위치에 해당하는 지화학 자료와 암상을 기준으로 의사결정나무를 학습시키고, 학습된 결과를 전체 자료에 적용하여 예측도면을 작성하였다. 광산이 존재하지 않은 지역을 추출하기 위하여 지화학도의 화소를 1km간격으로 추출한 후 이들 중 광산과 750m이내에 있는 자료는 제외시키는 알고리듬을 활용하였다. 예측결과 베이시안 방법에 의한 광산의 위치 예측이 의사결정나무에 의한 예측보다 상대적으로 정확함이 확인되었다. 그러나 두 방법 모두 공히 기존의 광산위치를 적절히 예측하고 있어서 지화학 자료는 광산의 위치와 밀접한 관계를 갖고 있음이 확인되었다.