• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2217-2221
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• 2011

We investigated the selective deoxyribonucleic acid (DNA) adsorption on layered double hydroxide (LDH) nanoparticles via studying the interaction between positively charged LDH nanoparticle as adsorbent and negatively charged adsorbates such as methyl orange (MO), fluorescein (FL), and DNA strands. The size controlled LDH $(Mg_{0.78}Al_{0.22}(OH)_2(CO_3)_{0.11}{\cdot}mH_2O)$ was prepared by conventional coprecipitation method, followed by the hydrothermal treatment. According to the adsorption isotherms, the adsorbed amounts of MO and FL were similar, however, that of DNA were much larger. The adsorption behaviors were well fitted to Freundlich adsorption model. The concentration dependent adsorption behavior on LDH surface was described in order to verify the selective DNA separation ability. The result showed that the LDH has advantages in selective adsorption of DNA competing with single molecular anions.

• 열처리공학회지
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• 제9권3호
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• pp.161-168
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• 1996

The purpose of this study is to investigate the effect of impurity level and fabrication processes on the strength, fracture toughness and fatigue resistance of 7075, 7050 and 7175 high strength aluminum forgings. It has been verified that plane strain fracture toughness and fatigue characteristics of a specially processed 7175S-T74 alloy is superior to a conventionally processed 7075-T6/T73, 7050-T74 and 7175-T74 alloys. These beneficial effects primarily arise from two view points, i.e., the effect of reducing the impurity level of iron and silicon has significantly diminished the size and volume fraction of second phase particles such as $Al_7Cu_2Fe$ and $Mg_2Si$. Futher reduction of the amount of nonequilibrium second phase particles has been observed by applying a special fabrication process.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.148-148
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• 2011

일반적으로 LED 제작에 사용되는 c-plane GaN는 c축 방향으로 발생하는 분극의 영향을 받게 된다. 분극은 LED내 양자우물의 밴드를 기울게 하여 그 결과 전자와 홀의 재결합 확률을 감소시켜 낮은 내부양자효율을 가지게 된다. 이러한 문제를 해결하기 위한 여러 가지 방법들이 제시되었는데 그 중에서도 특히 a-plane 혹은 m-plane면과 같은 무분극 면을 사용하는 GaN LED가 주목받고 있다. 그 이유는 무분극 면은 분극이 발생하는 c축과 수직이기 때문에 분극의 영향을 받지 않아 높은 내부 양자효율을 가질수 있다. 본 연구에서는 MOCVD 장비를 사용하여 2인치 r-plane 사파이어 기판위에 3um두께의 a-plane GaN을 성장하였다. 그위에 2um정도로 Si을 도핑하여 n-type GaN 형성한후 단일 양자우물, 그리고 Mg을 도핑하여 p-type GaN을 성장하였다. 장파장대역의 a-plane LED의 특성을 알아보기 위해서 양자우물 형성시 In의 조성비를 높였다. 일반적인 포토리소그래피 공정과 Dry etching 공정을 사용하여 메사구조를 형성하였으며 Ti/Al/Pt/Au와 Ni/Au를 각각 n-type과 p-type의 전극 물질로 사용하였다. 제작된 LED의 특성을 파악하기 위해서 인가전류를 0부터 100mA까지 출력 스펙트럼을 측정하였으며 orange대역의 파장을 갖는 LED를 얻었다. 인가전류별 Peak 파장의 변화와 반측폭의 변화를 파악하여 장파장 대역의 a-plane LED의 특성을 확인하였다.

• 한국토양비료학회지
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• 제33권3호
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• pp.205-211
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• 2000

제강슬래그 시용 1년 후 논토양의 토양화학성분 함량, 벼의 생육, 그리고 수량에 대한 제강슬래그의 잔류효과를 밝히려 1997년에 Lim등 (2000)이 설치한 포장 중유정리와 남평의 포장을 그대로 보존하였다가 1998년에 동일품종과 동일재배 방법을 이용하여 벼를 재배하였다. 이앙 후 2주 간격으로 4~6회에 걸쳐 초장과 주당분얼수를 조사하였으며 생육중기와 수확기에 토양 표본을 채취하여 토양의 주요 무기화학성분함량을 조사하였고 수확시 수량 및 수량 구성요소를 조사하였다. 유정리논이나 남평논 모두 비슷한 토양화학성분 함량에서의 변이를 보였다. 제강슬래그 처리구의 토양 pH와 Ca 함량은 7월까지 무처리구에 비하여 유의적으로 높은 값을 보인 후 점차 감소하였으며 제강슬래그 시용 수준이 높을수록 그 지속 기간이 길어지는 경향이어서 토양 Ca의 공급원이나 산성토양개량제로서 제강슬래그의 효과는 2년정도 지속되는 것으로 생각된다. 제강슬래그 $4Mg\;ha^{-1}$ 시용수준의 pH 상승효과는 석회 $2Mg\;ha^{-1}$ 처리보다 다소 높거나 비슷한 경향이었다. $SiO_2$ 함량은 슬래그 시용구에서 무처리구보다 유의하지는 않지만 높은 경향을 보였다. Fe나 Mg 함량은 제강슬래그 시용 1년차에는 무처리구에 비하여 유의적으로 높았으나 2년차에는 점차 무처리구와 비슷한 수준으로 안정되었다. 유정리논 벼의 정조수량은 슬래그 시용수준이 높을수록 증가하는 경향이었다. 석회 $2Mg\;ha^{-1}$ 처리구의 정조수량은 제강슬래그 $4Mg\;ha^{-1}$ 시용수준과 비슷하였다. 최대치를 보인 제강슬래그 $12Mg\;ha^{-1}$ 처리구의 정조수량은 $5,400kg\;ha^{-1}$로 무처리구의 $4,720kg\;ha^{-1}$에 비하여 14%의 증수효과가 있었다. 제강슬래그 $12Mg\;ha^{-1}$ 처리구는 생육초기의 초장생장이 빠르고 생육중기 이후 적정수의 주당 분얼수가 비교적 일정하게 유지되며 수화기의 주당수수는 적은 반면 천립중이 높은 경향이었다. 남평논 벼의 정조수량은 석회 $2Mg\;ha^{-1}$, 제강슬래그 12, 8, $4Mg\;ha^{-1}$, 무처리구의 순으로 많았다. 제강슬래그 처리중 정조수량이 가장 많은 제강슬래그 $12Mg\;ha^{-1}$ 처리의 정조수량은 $7,170kg\;ha^{-1}$로 무처리구의 $6,670kg\;ha^{-1}$에 비하여 8%의 유의적인 증수효과가 있었다. 제강슬래그 $12Mg\;ha^{-1}$ 처리구는 무처리구에 비하여 생육초기의 초장생장은 느린 반면 생육중기 이후의 초장생장이 양호한 생장특성을 보였고 수당립수와 천립중이 유의적으로 많았다.

• 한국대기환경학회지
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• 제24권5호
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• pp.594-603
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• 2008

A single particle analytical technique, named low-Z particle electron probe X-ray microanalysis, was applied to characterize four samples collected at an underground shopping area connected to Dongdeamun subway station, in January and May 2006. Based on the analysis of their chemical compositions of the samples, many distinctive particle types are identified and the major chemical species are observed to be soil-derived particles, iron-containing particles. sulfates. nitrates, and carbonaceous particles. which are encountered both in coarse and fine fractions. Carbonaceous particles exist in carbon-rich and organic. Soil derived particles such as aluminosilicates, AlSi/C, $CaCO_3\;and\;SiO_2$ are more frequently encountered in spring samples than winter samples. Nitrate- and sulfate-con taming particles are more frequently encountered in winter samples, and those nitrate- and sulfate-containing particles mostly exist in the chemical forms of $Ca(CO_3,\;NO_3),\;Ca(NO_3,\;SO_4),\;(Na,\;Mg)NO_3\;and\;(Mg,\;Na)(NO_3,\;SO_4)$. Fe-containing particles which came from nearby subway platform are in the range of about 10% relative abundances for all the samples. It is observed that nitrate- and sulfate-containing particles and carbonaceous particles are much more frequently encountered in indoor aerosol samples than in outdoor aerosols, implying that $NO_x,\;SO_x$, and VOCs at the underground shopping area were more partitioned into aerosol phase.

• 한국광물학회:학술대회논문집
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• 한국광물학회.한국암석학회 2001년도 공동학술발표회 논문집
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• pp.38-39
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• 2001

The seasonal changes in pH, Fe, Al and SO$_4$$\^$2-/ contents of acid drainage released from coal mine dumps play a major role in precipitation of metal hydroxides in the Taebaek coal field area, southeastern Korea. Precipitates in the creeks underwent a cycle of the color change showing white, reddish brown and brownish yellow, which depends on geochemical factors of the creek waters. White precipitates consist of Al-sulfate (basaluminite and hydrobasaluminite) and reddish brown ones are composed of ferrihydrite and brownish yellow ones are of schwertmannite. Goethite coprecipitates with ferrihydrite and schwertmannite. Ferrihydrite formed at higher values than pH 5.3 and schwertmannite precipitated below pH 4.3, and goethite formed at the intermediate pH range between the two minerals. With the pH being increased from acid to intermediate regions, Fe is present both as schwertmannite and goethite. From the present observation, the most favorable pH that basauluminte can precipitate is in the range of pH 4.45-5.95. SEM examination of precipitates at stream bottom shows that they basically consist of agglomerates of spheroid and rod-shape bacteria. Bacteria species are remarkably different among bottom precipitates and, to a less extent, there are slightly different chemical compositions even within the same bacteria. The speciation and calculation of the mineral saturation index were made using MINTEQA2. In waters associated with yellowish brown precipitates mainly composed of schwertmannite, So$_4$ species is mostly free So$_4$$\^$2-/ ion with less AlSo$_4$$\^$+/, CaSo$\sub$(aq)/, and MgSo$\sub$4(aq)/. Ferrous iron is present mostly as free Fe$\^$2+/, and FeSo$\sub$4(aq)/ and ferric iron exists predominantly as Fe(OH)$_2$$\^$+/, with less FeSo$\sub$4(aq)/, Fe(OH)$_2$$\^$-/, FeSo$_4$$\^$-/ and Fe$\^$3+/, respectively Al exists as free Al$\^$3+/, AlOH$_2$$\^$-/, (AlSo$_4$)$\^$+/, and Al(So$_4$)$\^$2-/. Fe is generally saturated with respect to hematite, magnetite, and goethite, with nearly saturation with lepidocrocite. Aluminum and sulfate are supersaturated with respect to predominant alunite and less jubanite, and they approach a saturation state with respect to diaspore, gibbsite, boehmite and gypsum. In the case of waters associated with whitish precipitates mainly composed of basaluminite, Al is present as predominant Al$\^$3+/ and Al(SO$_4$)$\^$+/, with less Al(OH)$\^$2+/, Al(OH)$_2$$\^$+/ and Al(SO$_4$)$\^$2-/. According to calculation for the mineral saturation, aluminum and sulfate are greatly supersaturated with respect to basaluminite and alunite. Diaspore is flirty well supersaturated while jubanite, gibbsite, and boehmite are already supersaturated, and gypsum approaches its saturation state. The observation that the only mineral phase we can easily detect in the whitish precipitate is basaluminite suggests that growth rate of alunite is much slower than that of basaluminite. Neutralization of acid mine drainage due to the dilution caused by the dilution effect due to mixing of unpolluted waters prevails over the buffering effect by the dissolution of carbonate or aluminosilicates. The main factors to affect color change are variations in aqueous geochemistry, which are controlled by dilution effect due to rainfall, water mixng from adjacent creeks, and the extent to which water-rock interaction takes place with seasons. pH, Fe, Al and SO$_4$ contents of the creek water are the most important factors leading to color changes in the precipitates. A geochemical cycle showing color variations in the precipitates provides the potential control on acid mine drainage and can be applied as a reclamation tool in a temperate region with four seasons.

• 한국약용작물학회지
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• 제2권2호
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• pp.162-167
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• 1994

국내에서 자생하고 있는 광릉쥐오줌풀 및 넓은잎 쥐오줌풀의 지하부에서 지방산, 무기성분 및 휘발성 유기산의 조성을 분석한 결과는 다음과 같다. 1. 광릉 및 넓은잎 쥐오줌플의 조지방질 함량은 $3.7{\sim}4.5%$ 범위 이었고 지방산은 총11종이 동정되었는데 그중 특히 양적으로 많이 함유되어있는 linoleic acid, linolenic acid 및 palmitic acid 등은 산지에 따라 함량차이가 큰 경향을 보였다. 2. 희분함량은 $4.3{\sim}6.3%$ 이었고 무기성분중 많이 검출된 성분으로는 조규소$(SiO_2)$를 위시하여 K, Na, Ca, Mg, Al, Fe, Mn, Zn등 이었으며, Na, Fe, Zn 및 Cu 는 산지에 따라 함량차이가 큰 경향을 보였다. 3. 광릉 쥐오줌풀로 부터 분리한 산성분획으로 부터 40종의 성분을 확인하였으며 그중 dimethoxy-2-propenoic acid, 3, 4-dimethoxy benzoic acid, 4-methoxy phenyl-2-propenoic acid 이외에도 3-methyl butanoic acid(isovaleric acid), 3-methyl pentanoic acid, 2-methyl butanoic acid 등 branched-chain fatty acid 류가 양적으로 많이 검출되었다.

• 약학회지
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• 제40권1호
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• pp.25-35
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• 1996

Magaldrate. an antiacid was synthesized by reacting magnesium oxide, aluminum sulfate, and dried aluminum hydroxide gel. The optimum synthesis conditions based on the yield of t he product were established by applying Box-Wilson experimental design. It was found that the optimum synthesis conditions of Magaldrate were as follows: Reaction temperature; 61~$85{\circ}C$, concentration of two reactants. Mgo and $Al(OH)_3$: 16~19.8%, molar concentration ratio of two reactants, [MgO]/[$Al(OH)_3$]; 4.2~5.0, temperature of washing water; 36~$41^{\circ}C$ and drying temperature of the product: 76~$80^{\circ}C$. Magaldrate was synthesized under the optimum synthesis conditions and identified by analyzing the chemical composition, and by differential scanning calorimetry and X-ray diffraction method. The Magaldrate sample synthesis under these conditions was used to prepare 15.6% Magaldrate original suspension which was utilized to make 13% Magaldrate suspension dispered in various concentrations of eight types of suspending agents. The acid-neutralizing capacity of 13% Magaldrate suspension dispersed in 0.25% suspending agents was examined by Rosset-Rice method. The maximum pH was reached within 1 minute in all suspension tested, and duration maintained between pH 3~5 was decreased in the order of Na alginate Na silicate(meta) Veegum HV pectin agar>Na>CMC>xanthan gum>bentonite. It was found that the hysteresis loop area was increased with temperature in the case of Riopan Plus and the addition of agar, whereas the area was decreased with temperature in the case of the addition of Na alginate and xanthan gum. 13% Magaldrate suspension tends to sediment by the addition of bentonite.

• 한국물환경학회지
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• 제26권5호
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• pp.725-731
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• 2010

This study was to evaluate the ozone oxidation of dissolved Fe, Mn, $SO{_4}^{2-}$ ions and color in abandoned mining drainage by conducting a bench-scale operation at various reaction times in an ozone reactor. The influent was collected from an abandoned mine drainage (AMD) near the J Mine in Jungsungun, Kangwon Province. The ozone reactor was operated at ozone reaction times of 10, 20 and 30 min with ozone doses of 0.0 and $2.4g\;O_3/hr$. Samples from each effluent from subsequent sand filtration were regularly collected and analyzed for pH, Fe, Mn, Al, Cr, Hg, $SO{_4}^{2-}$, alkalinity, color, ORP, TDS and EC. The effluent concentrations of Fe and Mn from the sand filter were less than 0.1 mg/L, which were below the concentrations on Korean drinking water quality standards (Fe, Mn < 0.30 mg/L). The influent $SO{_4}^{2-}$, concentrations were not noticeably changed during this ozone oxidation. Cr and Hg in the raw wastewater from the abandoned mining drainage were not detected in this study. The experimental result shows that the ozone oxidation of dissolved heavy metals and subsequent sand filtration of metal precipitates are desirable alternative for removing heavy metals in AMD.

• 한국생활과학회지
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• 제11권4호
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• pp.391-400
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• 2002

This study was intended to research the dyeing with natural walnut hull extracts over cotton, flax, rayon, wool, nylon and silk. We studied the dyeing conditions and mordant effect, and observed dyeability. The result are as follows: 1. In the dyeability with natural walnut hull extracts, protein and polyamide fiber has more dye uptake rather than cellulose fiber. 2. The optimum condition in the dyeing with natural walnut hull extracts was at $90^{\circ}C$, 12%(o.w.b) concentration in 90 mins. 3. In the case of the dyeability by repeated dyeing number, the dyeability of good dyeability fiber is improved in the first or second dyeing, but that of bad dyebality fiber is improved when it is dyed more repeatedly. 4. In the dyeablity treated with mordants, Al, Sn, and Mg don't have any differences, but Cu and Fe have some difference. The color of Fe mordant is green and the color of Cu mordant is blue. 5. In the case of the color fastness with mordant treatment, nylon is better than silk and wool in color fastness to washing but silk is better than nylon and wool in color fastness to light.