• 한국대기환경학회지
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• 제26권4호
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• pp.420-431
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• 2010

The water-soluble components have been analyzed from the total suspended particulate (TSP) collected at Gosan site of Jeju Island for ten years (1997~2006), and the long-term variations of ionic constituent concentrations have been investigated in order to understand the pollution characteristics of atmospheric aerosols. Their mean concentrations were in the order of nss-${SO_4}^{2-}$ > $Na^+$ > ${NO_3}^-$ > $Cl^$ > ${NH_4}^+$ > nss-$Ca^{2+}$ > $K^+$ > $Mg^{2+}$. The ${NO_3}^-$ concentrations had increased somewhat smoothly compared to those of ${SO_4}^{2-}$ for the past 10 years, possibly indicating the recent energy consumption pattern changes in China. The concentrations of ionic aerosol components showed mostly higher values during the Asian Dust storm periods, and the concentration ratios of nss-$Ca^{2+}$, ${NO_3}^-$, and nss-${SO_4}^{2-}$ between the Asian Dust and Non-Asian Dust periods were 6.9, 2.4, and 1.3, respectively. The anthropogenic nss-${SO_4}^{2-}$, ${NO_3}^-$, ${NH_4}^+$ and the soil originated nss-$Ca^{2+}$ components showed high concentrations as the air parcels were moved from the Asia continent, on the other hand, their concentrations were relatively low as moving from the Northern Pacific into the Gosan area.

• 한국세라믹학회지
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• 제47권1호
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• pp.86-91
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• 2010

Among various fuel cells, solid oxide fuel cells (SOFCs) offer the highest energy efficiency, when taking into account the thermal recycling of waste heat at high temperature. However, the highest efficiency and lowest pollution for a SOFC can be achieved through the sophisticated control of its constituent components such as electrodes, electrolytes, interconnects and sealing materials. The electrochemical conversion efficiency of a SOFC is particularly dependent upon the performance of its electrode materials. The electrode materials should meet highly stringent requirements to optimize cell performance. In particular, both mass and charge transport should easily occur simultaneously through the electrode structure. Matter transport or charge transport is critically related to the configuration and spatial disposition of the three constituent phases of a composite electrode, which are the ionic conducting phase, electronic conducting phase, and the pores. The current work places special emphasis on the quantification of this complex microstructure of composite electrodes. Digitized images are exploited in order to obtain the quantitative microstructural information, i.e., the size distributions and interconnectivities of each constituent component. This work reports regarding zirconia-based composite electrodes.

• 대한화학회지
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• 제43권2호
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• pp.199-205
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• 1999

PAN-PVDF-PEGME 블랜드(blend)계의 고분자전해질을 만들어 전기화학적인 특성을 조사하였으며 PEGME의 첨가에 따른 물성변화를 측정하였다. PEGME가 첨가되면서 PVDF의 결정성은 감소하고, 이온 전도도는 대부분 $∼10^{-3}S/cm$의 이온전도도를 나타내므로 고분자전해질로 사용이 가능하다. 또한 이온전도도의 온도의존성으로부터 PEGME의 첨가양이 증가할수록 효과적으로 높은 이온전도도를 갖는 통로가 생겨 이온전도도가 증가하는 것으로 예상할 수 있다. SPE 2(10 wt% PEGME)에서 가장 큰 양이온 수율을 나타내고 있으며 PEGME의 양이 증가할 수록 감소하는 것을 알 수 있다. PEGME를 첨가하지 않은 SPE 1(PAN-PVDF계) 고분자전해질의 전기화학적으로 안정한 영역은 ∼4.3 V인 반면에 PEGME를 첨가한 SPE 2-4(PAN-PVDF-PEGME계) 고분자전해질은 ∼4.6 V까지 전기화학적으로 안정한 것을 알 수 있다. 또한 이 고분자전해질을 사용하여 전지를 구성하여 충방전 성능을 비교하여 보면 PEGME를 첨가함에 따라 방전 용량이 증가함을 알 수 있다. 즉 PEGME를 첨가함에 따라 이온전도도가 증대되며, 전기화학적으로 안정한 영역이 넓어질뿐만 아니라 전지구성시 방전 성능도 향상됨을 알 수 있다.

• 한국대기환경학회지
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• 제24권6호
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• pp.682-692
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• 2008

Fine particles ($PM_{2.5}$) were collected and analyzed from November 2005 through August 2007 in Chuncheon, Korea to investigate the characteristics of $PM_{2.5}$ and its ionic constituents. The average $PM_{2.5}$ concentration during the study period was $39{\mu}g/m^3$, which is almost two times higher than the annual US NAAQS $PM_{2.5}$ standard of $15{\mu}g/m^3$. $PM_{2.5}$ concentrations were higher in spring and winter than in summer and fall. During spring, Asian Dust events dramatically enhanced $PM_{2.5}$ concentrations, and long-range transport of $PM_{2.5}$ emitted in industrial area of China often occurred during winter based on trajectory analysis. Contribution of $PM_{2.5}$ to $PM_{10}$ concentrations ranged from $72{\mu}g/m^3$ during Asian Dust events to $457{\mu}g/m^3$, indicating that a large portion of $PM_{2.5{\sim}10}$ was transported from China during Asian Dust events. Among the major ionic constituents ${SO_4}^{2-}$ showed the highest concentration, followed by ${NH_4}^+$, ${NO_3}^-$ and ${NO_2}^-$. Chuncheon appeared to be ${NH_4}^+$ rich environment, indicating that $(NH_4)_{2}SO_4$ and ${NH_4}{NO_3}$ were the predominant forms of ${NO_3}^-$ and ${SO_4}^2$ in $PM_{2.5}$. Haze has frequently occurred in Chuncheon since So-Yang dam was constructed in 1973. Haze events were observed on 23 days during sampling period, and the average $PM_{2.5}$ concentration was approximately 1.6 times higher during haze events than during non-haze events. This result suggests that haze enhances the secondary aerosol formation because the aerosol spontaneously absorbs water to form a saturated salt solution, deriving a significant increase in the mass of the particle.

• 한국암석학회:학술대회논문집
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• 한국암석학회.한국광물학회 2000년도 공동학술발표회 논문집
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• pp.3-11
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• 2000

The earth environment consists of four spheres : geosphere, hydrosphere, atmosphere and biosphere. The geosphere consists mostly of minerals. It, however, contains some water and air in its shallow depth. Although hydrosphere and atmosphere consist predominantly of water and air, respectively, both contain some minerals. The biosphere consisting of various organisms is present in the interfaces of geosphere, hydrosphere and atmosphere. The natural environment of the earth is continuously changing by the interaction of four spheres. It suggests that out relevant environmental problems can not be revolved without understanding the natural relationship of these four spheres. Minerals in our environment are very important because they are the main constituent materials of the earth and they control our environment. The roles of minerals in our environment have not been understood even in the scientific society. Thus their roles have been neglected. Review of studies on the environmental mineralogy so far made at our laboratory and others show that minerals control the environment in various ways. Minerals neutralize the acid water as well as acid rain. Minerals in soils and rocks are major neutralizer of the acid rain. Salinization of sea water is attributed to the ionic substitution between minerals and sea water. Some minerals control the humidity of the air. Corals, the products of biomineralization, are the main carbon controller of the air. Minerals also adsorb heavy metals, organic pollutants and radioactive nuclides. Such remarkable functions for controlling the environment come from the mineral-water reaction and biomineralization. All these phenomena are subjects of the environmental mineralogy, a new field of earth science.

• 한국세라믹학회지
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• 제17권2호
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• pp.61-68
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• 1980

The effect of the addition of various fluoreides on the mullitization of Korean crude kaolin was studied by X-ray powder diffraction and scanning electron microscopic methods. Kaolin without any addition of fluoreides began to be transformed into the mullite at 1, 10$0^{\circ}C$. Mullite peaks were discernible in the X-ray diffraction patterns of the specimens which contained fluorides equivalent to about 2 wt % fluorine, and which were sintered at 1, 05$0^{\circ}C$. The higher the concentration of fluorine in kaolin, the lower was the initiatinig temperature of mullitization. Experiments , for example, showed that mullite could be formed at 95$0^{\circ}C$ from kaolin mixed with 3.4% fluorine. Of the fluoride, addtives, sodiumsiliconfluoride $(Na_2SiF_6)$ was must effective in mullite formation of kaolin. In order of accelerating mullitization, the fluorides except $Na_2SiF_6$ could be placed in following sequence ; (1) sodium (NaF) (2) aluminium$(AlF_3)$ (3)potassium(KF) (4) ammonium$(NH_4F)$ (5) magnesium$(MgF_2)$ (6) calcium$(CaF_2)$. It was considered that the intrinsic characteristics of fluorides, such as size of ionic radiu, charge , bond strength between cation and anion, and electronegativity of cation affected millitization of halloysite, a main constituent mineral of kaolin.

• 한국정보통신학회논문지
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• 제5권6호
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• pp.1136-1142
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• 2001

$Zn_xSr_{1-x}S$ 박막을 sputtering법에 의해 제작하여 결정구조, 결합상태, 광학적 특성 등의 분석에 의해 고용체 유무를 판단하고 유전체 이론과 비교.검토하였다. 실험 결과 $0.86~0.93{\leq}x{\leq}1$에서 zincblende구조, $0{\leq}x{\leq}0.29$ 범위에서 rocksalt 구조의 고용체로 되었으며, 이들 영역에서는 격자정수, 결합에너지 및 흡수단은 조성에 따라 거의 직선적으로 변화했다. 상분리 영역을 포함한 miscibility gap은 $0.3{\leq}x{\leq}0.86~0.91$범위에서 존재하고 이 영역에서의 격자정수, 결합에너지 및 흡수단은 경계 조성의 값으로 일정했다. 상전이에 관한 실험결과는 Phillips의 유전이론에 기초한 이온성과 일치하였다.

• Biomolecules & Therapeutics
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• 제19권3호
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• pp.342-347
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• 2011

In the present study, the anticonvulsant effects of Artemisia capillaris Herba (AC) and its major constituent, esculetin (ECT), were tested and the mechanism studied. Locomotion, Myorelaxation, motor coordination and electroshock seizure experiment were conducted in mice. To identify the anticonvulsant mechanism effect of this drug, chemical-induced seizure in mice and the ionic movement in neuroblastoma cells were also observed. The ethanol extract of AC was orally administered to mice 30 min. prior to testing and ECT was intraperitoneally injected. AC and ECT treatment did not change locomotor activities as well as activities on the rota-rod, which indicates that they did not cause a sedative and myorelaxation effect. AC and ECT treatment increased threshold of convulsion induced by electroshock. AC treatment also inhibited convulsion induced by pentylenetetrazole. In the case of strychnine however, only high dose of AC treatment inhibited convulsion. AC and ECT treatment increased the $Cl^-$ influx into the intracellular area in a dose-dependent manner. On the other hand, bicuculline, a GABA antagonist, inhibited the $Cl^-$ influx induced by AC and ECT. These results indicate that ECT induces the anticonvulsive effect of AC extract through the GABAergic neuron.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.660-664
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• 2001

$Zn_xSr_{1-x}S$ 박막을 sputtering법에 의해 제작하여 결정구조, 결합상태, 광학적 특성 등의 분석에 의해 고용체 유무를 판단하고 유전체 이론과 비교.검토하였다. 실험결과 $0.86~0.93{\leq}x{\leq}1$에서 zincblende 구조, $0{\leq}x{\leq}0.29$범위에서 rocksalt구조의 고용체로 되었으며, 이들 영역에서는 격자정수, 결합에너지 및 흡수단은 조성에 따라 거의 직선적으로 변화했다. 상분리 영역을 포함한 miscibility gap은 $0.3{\leq}x{\leq}0.86~0.91$범위에서 존재하고 이 영역에서의 격자정수, 결합에너지 및 흡수단은 경계 조성의 값으로 일정했다. 상전이에 관한 실험결과는 Phillips의 유전이론에 기초한 이온성과 일치하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.325-325
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• 2007

The perovskites in the $LaAlO_3-BaZrO_3$ system (i.e., $(1-x)LaAlO_3-xBaZrO_3$ were fabricated by a solid state reaction and their dielectric properties were investigated. For the compositions of x=0.1~0.9, the mixture of $LaAlO_3$ with a rhombohedral structure and $BaZrO_3$ with a cubic was observed when the sintering was conducted at $1500^{\circ}C$, indicating that the solubility of constituent elements was very low and a narrow solid solution region might exist. The large difference of ionic radii between $La^{3+}$ ion (0.136nm, C.N.=12) and $Ba^{2+}$ ion (0.161nm) or $Al^{3+}$ ion (0.0535nm, C.N.=6) and $Zr^{4+}$ ion (0.072nm) might hinder the mutual substitution. Within the compositions of x=0~0.7, the dielectric constant of the mixture increased with the amount of $BaZrO_3$, i.e., x value, which was in good agreement with the logarithmic mixing rule (In $_{r,i}={\Sigma}v_iln\;_{r,i}$). The increase in $BaZrO_3$ doping decreased $Q{\times}f$ value significantly due to the low $Q{\times}f$ value of $BaZrO_3$ itself, a poor microstructure of the mixture with an increased grain boundary area per volume, and defects in the cation and oxygen sub-lattices which were respectively caused by the evaporation of barium during the sintering process and the substitution of Ba on La-site or Al on Zr-site.