• 한국재료학회지
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• 제21권4호
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• pp.236-241
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• 2011

Polysilazane and silazane-based precursor films were deposited on stacked TiN/Ti/TEOS/Si-substrate by spin-coating, then annealed at $150{\sim}400^{\circ}C$, integrated further to form the top electrode and pad, and finally characterized. The precursor solutions were composed of 20% perhydro-polysilazane ($SiH_2NH$)n, and 20% hydropolymethyl silazane ($SiHCH_3NH$)n in dibutyl ether. Annealing of the precursor films led to the compositional change of the two chemicals into silicon (di)oxides, which was confirmed by Fourier transform infrared spectroscopy (FTIR) spectra. It is thought that the different results that were obtained originated from the fact that the two precursors, despite having the same synthetic route and annealing conditions, had different chemical properties. Electrical measurement indicated that under 0.6MV/cm, a larger capacitance of $2.776{\times}10^{-11}$ F and a lower leakage current of 0.4 pA were obtained from the polysilazane-based dielectric films, as compared to $9.457{\times}10^{-12}$ F and 2.4 pA from the silazane-based film, thus producing a higher dielectric constant of 5.48 compared to 3.96. FTIR indicated that these superior electrical properties are directly correlated to the amount of Si-O bonds and the improved chemical bonding structures of the spin-on dielectric films, which were derived from a precursor without C. The chemical properties of the precursor films affected both the formation and the electrical properties of the spin-on dielectric film.

• 한국재료학회지
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• 제21권1호
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• pp.21-27
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• 2011

A nano-porous structure of tin oxide was prepared using an anodic oxidation process and the sample's electrochemical properties were evaluated for application as an anode in a rechargeable lithium battery. Microscopic images of the as-anodized sample indicated that it has a nano-porous structure with an average pore size of several tens of nanometers and a pore wall size of about 10 nanometers; the structural/compositional analyses proved that it is amorphous stannous oxide (SnO). The powder form of the as-anodized specimen was satisfactorily lithiated and delithiated as the anode in a lithium battery. Furthermore, it showed high initial reversible capacity and superior rate performance when compared to previous fabrication attempts. Its excellent electrode performance is probably due to the effective alleviation of strain arising from a cycling-induced large volume change and the short diffusion length of lithium through the nano-structured sample. To further enhance the rate performance, the attempt was made to create porous tin oxide film on copper substrate by anodizing the electrodeposited tin. Nevertheless, the full anodization of tin film on a copper substrate led to the mechanical disintegration of the anodic tin oxide, due most likely to the vigorous gas evolution and the surface oxidation of copper substrate. The adhesion of anodic tin oxide to the substrate, together with the initial reversibility and cycling stability, needs to be further improved for its application to high-power electrode materials in lithium batteries.

• 한국결정성장학회지
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• 제25권3호
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• pp.111-115
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• 2015

$Er^{3+}$ 이온이 5, 7.3, 8, 10 at.% 치환된 $Y_3Al_5O_{12}$ 단결정을 Czochralski법으로 질소 분위기에서 성장시켰다. 1.0 mm/h의 인상속도와 10 rpm의 회전 속도로 50 mm의 결정 직경을 가진 <111> 방향의 $Er:Y_3Al_5O_{12}$ 단결정을 얻었다. 두꺼운 직경의 core 영역은 주로 결정 성장 중 직경 변화가 있는 영역에서 발생되었다. 결정 내에서 $Er^{3+}$의 농도는 융액 내의 농도와 같았다. Core 영역의 $Er^{3+}$ 농도는 core가 없는 영역보다 다소 높게 검출되었다. $Er^{3+}$ 이온의 도핑 농도가 증가함에 따라 형광 수명은 포화되었다.

• Corrosion Science and Technology
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• 제3권3호
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• pp.112-117
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• 2004

This work investigated the material properties of Ni-P-B alloy electrodeposits obtained from a Ni sulfamate bath as a function of the contents of the P and B sources($H_3PO_3$ and dimethyl amine borane complex(DMAB), respectively) with/without additives. Chemical composition, residual stress, microstructure and micro hardness were investigated using ICP(inductively coupled plasma) mass spectrometer, flexible strip, XRD, TEM and micro Vickers hardness tester, respectively. From the results of the compositional analysis, it was observed that P and B are incorporated competitively during the electrodeposition and the sulfur from the additive is codeposited into the electrodeposit. The measured residual stress value increased in the order of Ni, Ni-P, Ni-B and Ni-P-B electrodeposits indicating that boron affects the residual tensile stress greater than phosphorus. As the contents of the alloying element sources of P and B increased, crystallinity and the grain size of the electrodeposit decreased. The effect of boron on crystallinity and grain size was also relatively larger than the phosphorus. It can be explained that the boron with a smaller atomic radius contributes to the increase of residual stress in the tensile direction and the larger restraining force against the grain growth more significantly than the phosphorus with a larger atomic radius. Introduction of an additive into the bath retarded crystallization and grain growth, which may be attributed to the change of the grain growth kinetics induced by the additive adsorbed on the substrate and electrodeposit surfaces during electrodeposition.

• Journal of Ecology and Environment
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• 제44권2호
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• pp.106-114
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• 2020

Background: Determining patterns of habitat use is key to understanding of animal ecology. Approximately 1% of bird species use brood parasitism for their breeding strategy, in which they exploit other species' (hosts) parental care by laying eggs in their nests. Brood parasitism may complicate the habitat requirement of brood parasites because they need habitats that support both their host and their own conditions for breeding. Brood parasitism, through changes in reproductive roles of sex or individual, may further diversify habitat use patterns among individuals. However, patterns of habitat use in avian brood parasites have rarely been characterized. In this study, we categorized the habitat preference of a population of brood parasitic lesser cuckoos (Cuculus poliocephalus) breeding on Jeju Island, Korea. By using compositional analyses together with radio-tracking and land cover data, we determined patterns of habitat use and their sexual and diurnal differences. Results: We found that the lesser cuckoo had a relatively large home range and its overall habitat composition (the second-order selection) was similar to those of the study area; open areas such as the field and grassland habitats accounted for 80% of the home range. Nonetheless, their habitat, comprised of 2.54 different habitats per hectare, could be characterized as a mosaic. We also found sexual differences in habitat composition and selection in the core-use area of home ranges (third-order selection). In particular, the forest habitat was preferentially utilized by females, while underutilized by males. However, there was no diurnal change in the pattern of habitat use. Both sexes preferred field habitats at the second-order selection. At the third-order selection, males preferred field habitats followed by grasslands and females preferred grasslands followed by forest habitats. Conclusions: We suggest that the field and grassland habitats represent the two most important areas for the lesser cuckoo on Jeju Island. Nevertheless, this study shows that habitat preference may differ between sexes, likely due to differences in sex roles, sex-based energy demands, and potential sexual conflict.

• Journal of Microbiology and Biotechnology
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• 제28권10호
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• pp.1626-1634
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• 2018

Ginseng (the root of Panax ginseng Meyer) fermented by Lactobacillus plantarum has been found to attenuate allergic responses in in vitro and in vivo experimental models. Ginseng has been reported to also possess various biological functions including anti-inflammatory activity. The present study was aimed at comparing the anti-allergic effect of ginseng and fermented ginseng extracts on IgE-mediated passive cutaneous anaphylaxis in vitro in a murine cell line and in vivo in mice. Fermented ginseng extract (FPG) showed higher inhibitory effect against in vitro and in vivo allergic responses when compared with ginseng extract (PG). The secretion of ${\beta}$-hexosaminidase and interleukin (IL)-4 from the IgE-DNP-stimulated RBH-2H3 mast cells were significantly (p < 0.05) inhibited by FPG treatment, and this effect was concentration-dependent. Further, MKK4 activation and subsequent JNK phosphorylation were attenuated by FPG treatment. The inhibitory effect of FPG on the in vitro allergic response was verified in vivo against IgE-DNP-induced passive cutaneous anaphylaxis in a mouse model. These data indicated that the fermentation of ginseng with L. plantarum enhanced its anti-allergic effects both in vitro and in vivo. We predict that compositional changes in the ginsenosides caused by the fermentation may contribute to the change in the anti-allergic effects of ginseng. The results of our study highlight the potential of the use of FPG as a potential anti-allergic agent.

• 한국분말재료학회지
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• 제24권5호
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• pp.377-383
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• 2017

Microstructure, electric, and thermal properties of the Ta-Cu composite is evaluated for the application in electric contact materials. This material has the potential to be used in a medium for a high current range of current conditions, replacing Ag-MO, W, and WC containing materials. The optimized SPS process conditions are a temperature of $900^{\circ}C$ for a 5 min holding time under a 30 MPa mechanical pressure. Comparative research is carried out for the calculated and actual values of the thermal and electric properties. The range of actual thermal and electric properties of the Ta-Cu composite are 50~300 W/mk and 10~90 %IACS, respectively, according to the compositional change of the 90 to 10 wt% Ta-Cu system. The results related to the electric contact properties, suggest that less than 50 wt% of Ta compositions are possible in applications of electric contact materials.

• 수산경영론집
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• 제47권3호
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• pp.53-69
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• 2016

The purpose of this study is to explore the ecosystem service and benefit indicators of natural seaweed beds. Ecosystems of natural seaweed beds provide a wide range of services and benefits to human society including provisioning services, regulating services, supporting services, and cultural services. Indicators for each of the ecosystem services are chosen by marine plants ecologists and as follows. Ecosystem indicators of natural seaweed beds for provisioning services are well-being food(amount of seaweed harvested/amount of fish landed, fish biomass, area of natural seaweed beds, the number of species, contribution to the second production), raw materials(amount of biomass by breed, amount of aquaculture feed), genetic resources(amount of genetic material extracted, amount of genetic material contained by age and habitat), and medicinal resources(amount of medicinal material extracted). Ecosystem indicators of natural seaweed beds for regulating services are air purification(amount of fine dust/NOx or $SO_2$ captured), climate regulation(amount of $CO_2$ sequestered), waste treatment(amount of N, P stored, biochemical degradation capacity COD), and costal erosion prevention(length and change of natural coast line, amount of sediment prevented). Ecosystem indicators of natural seaweed beds for supporting services are lifecycle and maintenance(primary production, contribution to the second production) and gene pool protection(amount of compositional factors in ecosystem, introduced species). Ecosystem indicators of natural seaweed beds for cultural services are recreation and tourism(the number of visits of an area) and information for cognitive development(amount of time spent in education, research and individual learning about ecosystem of natural seaweed beds).

• 한국결정학회지
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• 제6권2호
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• pp.111-117
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• 1995

화학증착법에 의해 TiO2 박막을 Si-wafer(100)위에 제조하였다. Titanium tetraisopropoxide (TTIP)를 출발물질로 하여 200-500℃의 온도범위에서 증착을 행하였다. 증착된 박막의 두께는 Ellipsometry 및 SEM을 사용하여 측정하였으며, 산소의 함량에 따른 증착층의 성분분석은 ESCA를 사용하였다. TiO2 박막의 증착속도는 산소의 함량에 따라 증가하였고, 반응가스인 산소를 공급하지 않았을 때 증착층내에 불순물로 탄소가 존재하였으며, 증착층의 성분은 내부로 갈수록 TiO2에서 Ti로 변하였다. 산소를 600scm 공급하였을 때 증착층내에 소량의 탄소가 존재하였으며, 증착층의 성분은 내부로 갈수록 TiO2에서 TiO, Ti로 됨을 알 수 있었다. 산소를 1200scm공급하였을 때 증착층내에 탄소가 존재하지 않았으며, 증착층 성분은 표면에는 TiO2를 이루나 증착층 내부로 갈수록 Ti복합화합물을 이루고 있었다.

• 접착 및 계면
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• 제13권2호
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• pp.64-72
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• 2012

비닐아세테이트와 알킬아크릴레이트계 에멀젼공중합에서 개시제인 ammonium persulfate (APS)의 농도, 보호 콜로이드인 poly(vinyl alcohol) (PVA)의 종류와 농도, 공단량체인 methyl acrylate (MA), ethyl acrylate (EA), n-butyl acrylate (BA)의 혼합비를 변화시켜 중합하였다. 제조된 poly(vinyl acetate-co-methyl acrylate) (PVAc/PMA), poly(vinyl acetate-co-ethyl acrylate) (PVAc/PEA), poly(vinyl acetate-co-n-butyl acrylate) (PVAc/PBA)에 대하여 다음과 같은 결론을 얻었다. 등온 열분해법으로 $100{\sim}200^{\circ}C$ 영역에서 구한 비닐아세테이트와 알킬아크릴레이트 공중합체에 대한 등온 열분해 활성화에너지는 PVAc/PMA > PVAc/PEA > PVAc/PBA이었으며, 플라스마 처리 전과 후의 접착박리강도는 PVAc/PMA > PVAc/PEA > PVAc/PBA의 순이었다.