• 대한화학회지
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• 제50권2호
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• pp.153-162
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• 2006

이 연구의 목적은 제7차 교육과정에 의한 중학교 과학 교과서의 화학 단원에 대한 STS (science-technology-society) 교육 내용을 분석하고, 화학 교사들의 STS 교육에 대한 인식을 조사하는데 있다. 연구를 위하여 Yager가 제시한 STS 교육에서의 8개 필수 요소와 SATIS (science and technology in society)에서의 9가지 활동 유형을 분석기준으로 삼았으며, 화학 교사들의 STS 교육에 대한 인식 조사를 위해 면담과 설문지를 병행하였다. 연구 결과에 의하면, 7종의 중학교 과학 교과서들의 화학 단원에 STS 교육 내용이 평균적으로 22.4%가 포함되어 있었으며, STS 교육 내용이 과학의 응용성과 지역 사회와의 연관성에 대한 필수 요소에 편중되어 있었다. 그리고 STS 교육 내용의 학년별 분포는 2학년 과학 교과서에 가장 많았고, 다음으로 1학년 과학 교과서와 3학년 과학 교과서 순서였다. SATIS 활동 유형으로는 실제활동 유형이 가장 많았고, 다음으로 문제해결 및 의사결정과 구조화된 토론 유형의 순서였다. 중등학교 화학 교사들의 STS 교육에 대한 인식 조사에서 STS 교육이 과학교육에 필요한 이유로는 교육의 효율성 측면에서 필요하다는 응답이 가장 많았으며, STS 교육이 필요 없다고 생각하는 이유에 대해서는 적절하고 효율적인 STS 교육 관련 교수-학습 방법이 없기 때문이라는 응답이 가장 많았다. 이러한 연구 결과로 볼 때, 중학교 과학 교과서의 STS 교육 내용이 필수 요소 2개에 편중되어 있기 때문에 이를 보완하는 작업과 더불어 다양한 활동 유형을 가진 중학교 과학 교과서들을 마련해야 할 필요가 있다. 또한, STS 교육 관련 교수-학습 방법의 개발을 통하여 STS 교육의 효율성을 높일 필요가 있는 것으로 생각된다.

• 한국광물학회:학술대회논문집
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• 한국광물학회.한국암석학회 2003년도 공동학술발표회 논문집
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• pp.54-54
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• 2003

The metasedimentary rocks together with various granitoids are the main constituents in Taebaeksan gneiss complex, northern Yeongnam Massif. Chemical compositions of sedimentary rocks may reflect the nature of the provenance and could be crucial for understanding the evolution of early continental crust. Previous workers have suggested that the provenance and tectonic studies based on the geochemistry of sediments are applicable to the Precambrian samples. In this study we analyzed the major, trace and REE elements of metasedimentary rocks to understand their provenance and tectonic setting during sedimentation. The overall geochemical characteristics of metasedimentary rocks are similar to those of average shale of the post-Archean. Major element chemistry indicates mature and sorted nature of the sediments. The degree of weathering in the source rocks the is not uniform, as inferred from a large scatter in chemical indices of weathering (CIW). The immobile trace elements such as Th, Sc, and REE can be used to discriminate various sedimentary processes. The Th/sc ratios (0.9 - 4.4) are larger than those of the upper crust and average shale, suggesting that the felsic source predominates. The contents of Ni and Cr and the variations in the ratio of compatible to incompatible elements are similar to the average post-Archean shale. Uniform chondrite-normalized REE pattern with the LREE enrichment (LaN/SmN = 4.9 ${\pm}$ 0.4) and slight negative Eu anomalies (Eu/Eu$\^$*/ = 0.7 ${\pm}$ 0.1) also support this observation. The presence of negative Eu anomaly indicates that intracrustal igneous processes involving plagioclase separation have affected the provenance rocks. The LREE enrichment implies the major role of felsic rocks in source rocks. The eNd (1.9 Ga) values of metasediment rocks vary from 9.4 to 6.7, corresponding to TDM of 2.9 - 2.7 Ga. On the other hand, the 147Sm/144Nd ratios are 0.1079 - 0.1101, corresponding to typical tettigenous sediments. The geochemical features of metasedimentary rocks such as high abundances of large ion lithophile elements, high ratios of Th/Sc and La/Sm, commonly high Th/U ratios, negative Eu anomalies, and negative eNd, suggest a provenance consisting virtually entirely of recycled upper continental crust in passive margin environment. Tectonic discrimination diagrams based upon major element compositions also support this suggestion. In conjunction with igneous activity and metamorphism in the convergent margin setting at 1.8 - 1. 9 Ga, the transition from passive margin to active margin characterize the Paleoproterozoic crustal evolution in northern Yeongnam Massif.

• 천문학회지
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• 제35권4호
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• pp.209-220
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• 2002

In order to increase the completeness of the investigations of stellar abundances, we can use spectrum synthesis method, new atomic data and observation of stellar spectra with resolution comparable to solar spectral atlases. We made a brief review of main problems of these three ways. We present new results of abundance determinations in the atmospheres of four stars. The first is the implementation of new atomic data to well known Przybylski's star. We show that the number of spectral lines, which can be identificated in the spectrum of this star, can be significantly higher. The second example is the investigation of $\zeta$ Cyg. We found the abundances of 51 elements in the atmosphere of this mild barium star. The third example is halo star HD221170. Our preliminary abundance pattern consists of 42 elements. The heaviest elements in this pattern are U and Th. The last star is the spectroscopic binary HD153720. The number of elements investigated in the spectra of components of this star is not large, but the results show that the components are Am-stars.

• 환경위생공학
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• 제17권2호
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• pp.71-78
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• 2002

This study was conducted to evaluate the concentration distribution characteristics of air pollutants by the yellow sand from China. The concentrations and chemical properties of FPM contained in the yellow sand were compared with those of air pollutants when having no yellow sand in order to estimate the variation characteristics and the originated source of air pollutants moved by yellow sand. The concentrations of PM-2.5 and PM-10 contained in the yellow sand showed an increase of 2.3 to 2.7 times than usual, and the concentrations of NO2 and SO2 in the gaseous pollutants showed an increase of about 1.6 times by yellow sand, and thus the air contamination was much influenced by yellow sand phenomenon. The concentrations of inorganic elements contained in FPM from the yellow sand showed a higher concentration variation in the order of Al>Mg>Zn>Pb than usual. The concentration coefficient of air aerosol during the yellow sand period showed that Na, K, Ca, Mg and Fe were originated from natural source, and Pb, Cr, Cd, Cu and Zn were originated from artificial source for inorganic elements. The correlation analysis between FPM and inorganic elements showed in the descending order of Al>K>Pb>Mg, and thus the deposited amount of Pb was influenced by that of yellow sand. The average concentrations of PM-10 measured during the yellow sand period exceeded the Korea Air Environmental Standard and showed a excess rate of 3.4 times in the maximum but the average concentrations of PM-2.5 showed within the United States Air Environmental Standard.

• 한국토양환경학회지
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• 제4권1호
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• pp.57-68
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• 1999

흔한 토양구성 광물인 일라이트(illite), 카올린 광물의 일종인 할로이사이트(halloysite), 제올라이트(clinoptilolite), 침철석(goethite)을 흡착제로 사용하여 산성용액 중에 존재하는 중금속원소들의 흡착특성을 비교하여 검토하였다. 금속원소의 흡착반응은 반응시간과 광물종에 따라서 다양한 특성을 보여 준다. 1주 또는 2주 동안 반응한 용액과 초기 용액간에는 존재하는 화학종들의 변화는 거의 없는데, 이는 개개의 원소들의 화학종의 변화를 수반하지 않으면서 처음의 상태와 비슷한 비율로 진행되고 있음을 나타낸다. 모든 광물에서 흡착되어 제거율이 가장 높은 원소는 Fe와 As이며 흡착반응은 광물의 종류와 중금속원소의 종류에 따라서 다양하지만 1시간 내에 대부분 일어난다. 중금속흡착은 전체적으로 보면 할로이사이트가 가장 효과적인 흡착능력을 보여준다. 한편 알칼리원소의 흡착은 수화반경에 의하여 예측되는 경향을 잘 따르지 않는다.

• 한국환경농학회지
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• 제20권5호
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• pp.317-324
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• 2001

Short-term effect of phosphogypsum on soil properties including acidification, salinity and metal availability were investigated under laboratory and field conditions. Phosphogypsum and mixtures of phosphogypsum and compost were added to soil and incubated in a laboratory condition with 15% moisture content. Phosphogypsum treatments were 2.5 and 5.0 g/kg soil and in the treatments of phosphogypsum and compost mixture 10 g of compost was added additionally. After the 30 days of incubation, an additional phosphogypsum and/or compost were added to the remaining soils at the same rates of the first treatments. pH, electrical conductivity, and available hazardous elements were measured periodically during the incubation. Field experiment was conducted in a plastic film house of mellon with four treatments of phosphogypsum and compost mixtures - 25+125, 50+125, 50+250 and 100+250 kg/165 $m^2$. pH, electrical conductivity, and hazardous elements in soil and total hazardous elements in leaf were measured. In the laboratory experiment, after 30 days of the first phosphogypsum application, soil pHs were lowered by 0.7-0.8 units. After the second treatment of phosphogypsum 0.2 units of additional acidification occurred. However, acidification was not observed in the soils treated with mixtures of phosphogypsum and compost. In the laboratory experiment, phosphogypsum treatments increased electrical conductivity very significantly. In field experiment, pH and electrical conductivity of soils treated with phosphogypsum were nearly the same as those of soil not treated with phosphogypsum. Since soil condition in the field study was an open system, the free acids and salts derived from phosphogypsum could be diffused down with water leaching through the soil profile and then any significant acidification or salt accumulation in the topsoil could not be observed. In both laboratory and field experiments, levels of available hazardous elements in soils treated with phosphogypsum were quite low and not different from the levels found in the control soil. Results obtained from this study suggest that application of phosphogypsum at appropriate rates on agricultural land appears of no concern in terms of acidity, salinity and hazardous element content of soil.

• 자원환경지질
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• 제29권4호
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• pp.495-508
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• 1996

This study had three purposes: (1) to investigate dispersion and enrichment level of potentially toxic elements; (2) to identify uranium-bearing minerals in black shales; and (3) to assess the chemical speciation of heavy metals in soils and sediments. Rock, surface soil and stream sediment samples were collected in the Chungjoo area covered with black shales in Korea. These samples were analyzed for multi-elements using INAA and ICP-AES. The maximum abundance of U in black shales is 56 ppm and radioactivity counts up to 240CPM. Molybdenum, V, Ba, Cu, and Pb are enriched in black shales and most of soils show high concentrations of U, Mo, Ba, Cu, Pb and Zn. Concentrations of potentially toxic elements decrease in the order of mountain soil > farmland soil > paddy soil. Enrichment index of soils and sediments are calculated and higher than 1.0 in the black shale area with the highest value of 6.1. In order to identify U-bearing minerals, electron probe micro analysis was applied, and uraninite and brannerite in black shale were found. Uraninite grains are closely associated with monazite or pyrite with the size of $2{\mu}m$ to $10{\mu}m$ in diameter whereas brannerite occurs as $50{\mu}m$ euhedral grains. With the results of sequential extraction scheme, residual fractions of Cu, Pb and Zn in soils are mainly derived from weathering of black shale but Cu, Pb and Zn in sediments are present as non-residual fractions. Lead is predominantly present as oxidizable phase in soils whereas Zn is in exchageable/water-acid soluble phase in sediments.

• 자원환경지질
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• 제36권4호
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• pp.275-284
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• 2003

구례지역의 1차 수계를 대상으로 하상퇴적물을 채취하여 지질집단별 주성분 및 미량성분원소의 자연배경치를 설정하고자 하였다. 하상퇴적물은 구례지형도에서 오염의 우려가 없고 단일지질로 구성된 집수분지를 대표할 수 있는 시료를 1999년 4월과 5월에 걸쳐 채취하였고 화학분석을 실시하였다 유해원소들의 부화정도를 알아보기 위해 tolerable level윽 이용하여 살펴본 결과 일부 지역에서 Ni과 Cr의 함량이 tolerable love의 허용한계치를 초과하는 것으로 나타나는데, 이는 이들 지역의 기반암인 변성암류의 영향으로 인한 것으로 판단된다. 유해금속원소의 종합적인 부화양상을 규명하기 위하여 tolerable level을 이용하여 부화지수를 산출한 격과, 화강편마암지역은 0.39, 반상변정질화강편 마암지역은 0.32, 흑운모편마암지역은 0.42, 혼성편마암지역은 0.41, 응회암지역은 0.30, 안산암지역은 0.46, 역암지역은 0.42, 화강암지역은 0.26으로 매우 낮은 부화지수를 보여주고 있는 것으로 보아 연구지역의 자연배경치는 유해금속원소의 오염에 노출되지 않은 것으로 판단된다.

• Corrosion Science and Technology
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• 제17권4호
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• pp.154-165
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• 2018

During the process of sulfur dioxide removal, flue gas desulfurization equipment provides a serious internal corrosion environment in creating sulfuric acid dew point corrosion. Therefore, the utilities must use the excellent corrosion resistance of steel desulfurization facilities in the atmosphere. Until now, the trend in developing anti-sulfuric acid steels was essentially the addition of Cu, in order to improve the corrosion resistance. The experimental alloy used in this study is Fe-0.03C-1.0Mn-0.3Si-0.15Ni-0.31Cu alloys to which Ru, Zn and Ta were added. In order to investigate the effect of $H_2SO_4$ concentration and the alloying elements, chemical and electrochemical corrosion tests were performed. In a low concentration of $H_2SO_4$ solution, the major factor affecting the corrosion rate of low alloy steels was the exchange current density for $H^+/H_2$ reaction, while in a high concentration of $H_2SO_4$ solution, the major factors were the thin and dense passive film and resulting passivation behavior. The alloying elements reducing the exchange current density in low concentration of $H_2SO_4$, and the alloying elements decreasing the passive current density in high concentration of $H_2SO_4$, together play an important role in determining the corrosion rate of Cu-bearing low alloy steels in a wide range of $H_2SO_4$ solution.

• 한국광물학회지
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• 제10권1호
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• pp.60-73
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• 1997

The talc of the Daeheung, Pyeongan, and Cheongdang (Shinyang) talc deposits in the Yesan-Gongju-Cheongyang area is a hydrothermal alteration product of serpentinite originated from ultramafic rocks. The mineral assemblages in alteration zones are: serpentine, serpentine-talc, talc, talc-chlorite, talc-phlogopite-chlorite, and talc-tremolite-chlorite. Chemical distributions in both the Al2O3-FeO-MgO system and the immobile elements suggest that the serpentine-talc and talc rocks are the reaction product of ultramafic rocks and silicic hydrothermal solution without addition of other granitic components, whereas chlorite-, phlogopite-, and tremolite-bearing rocks are the metasomatic alteration product of serpentinite by hydrothermal solution affected by granitic gneiss. Discontinuities in the immobile element ratios of mineral assemblages are due to changes in their mineralogy. The relative contents of Al2O3, TiO2, Zr in the talc-phlogopite-chlorite and talc-tremolite-chlorite rocks increase irregularly with increasing phlogopite, tremolite, and/or chlorite contents in contrast to other ore types. But the relative contents of Cr, Ni, and Co are uniform in all the mineral assemblages. Chemistry of each mineral assemblage formed by steatitization of serpentinite suggests that Cr, Co, Ni, MgO, and Fe2O3 are relatively immobile during the alteration, whereas SiO2, Al2O3, CaO, and K2O are highly increased. The contents of chlorite, phlogopite, and tremolite in each mineral assemblage might be controlled by addition of Al2O3, K2O, and CaO, respectively. The high contents of other elements than immobile elements in the altered rocks as compared with unaltered rocks indicate that a large amount of elements were introduced from hydrothermal solution up to about 8∼41% in total mass showing maximum value in the talc-phlogopite-chlorite rock.