• 한국전기전자재료학회논문지
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• 제25권5호
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• pp.392-397
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• 2012

In the $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1})O_3$ (LCCC), which has been using as interconnector materials in SOFC, Al ions were substituted for Co because ionic radius of Al is similar to that of Co. Because of the almost identical ionic radius of Al and Co, the substitution was not thought to be affect the tolerance factor of LCCC, and the densification behavior, high temperature electrical conductivity and thermal expansion coefficient were examined as a function of Al concentration. In the cases of the x= 0 and x= 0.02 in $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1-x}Al_x)O_3$ (x= 0~0.1), the samples showed the relative densities above ${\geq}95%$ when those were sintered at ${\geq}1,350^{\circ}C$. In the case of the $x{\geq}0.06$ the sintered density deteriorated greatly at lower sintering temperatures. High temperature electrical conductivity of the samples decreased as the content of Al increased. Since the valence state of Al ion is unchangeable, while Cr or Co ions contribute to the electrical conduction by changing those valence states, Al substitution resulted in the decreased electrical conductivity. Al doping of LCCC was an effective way of decreasing the thermal expansion coefficient (TEC).

• 한국환경농학회지
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• 제18권2호
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• pp.169-173
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• 1999

경기 남부지역 빗물의 화학적 특성을 알아보기 위하여 1998년 5월부터 10월까지 6개월 동안 수원과 안성지역에 내린 빗물을 채취하여 화학성분을 분석하였으며, 분석결과에 대한 신뢰성을 검토한 결과는 다음과 같다. 각 분석시료에 대한 양이온과 음이온의 균형과 전기전도도의 이론치와 실측치간의 관계를 조사한 결과, 고농도 시료를 제외하고는 분석의 신뢰성이 인정되었다. 조사기간중 빗물의 pH 분포는 수원과 안성지역 모두 pH $5.0{\sim}5.6$ 범위에서 각각 37.9%, 35.3%로 가장 많았으며, 강우량별 빗물의 이온함량과 pH 변화는 초기빗물(1mm 이하)가 그 이후의 빗물에 비해 높았다. 빗물의 조성은 $SO_4^{2-}$와 $NO_3^-$가 음이온의 약 85% 그리고 양이온은 $NH_4^-,\;Ca^{2+}$ 및 $Na^+$가 약 80%를 차지하고 있다. 월별 빗물의 pH는 8월과 9월에 수원지역은 4.5와 4.2 그리고 안성지역은 4.6과 4.7로 그외 조사시기 보다 낮았고 조사지역 빗물중 비해염(非海鹽) sulfate는 두 지역 모두 총sulfate 함량의 약 97%이었다. 빗물의 $nss-SO_4^{2-}/NO_3^-$은 평균 수원지역 2.2와 안성지역 빗물 2.9로 비해염 $SO_4^{2-}$에 의한 기여울은 안성지역이 수원지역보다 높았다.

• 한국지반환경공학회 논문집
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• 제13권9호
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• pp.31-44
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• 2012

김해 딴섬 지역 지하수는 갈수기와 홍수기의 계절에 따른 지구화학 특성의 변화를 보인다. 농번기인 4월의 이온의 공간적 분포를 보면 $Fe^{2+}$, Fe(total), $Mn^{2+}$, $Ca^{2+}$, $Mg^{2+}$, $SiO_2$, ${HCO_3}^-$ 및 ${NO_3}^-$는 딴섬의 중앙부에서 높고 $Na^+$ 및 $K^+$는 딴섬 중앙부가 낮은값을 보이는데 높은 ${HCO_3}^-$ 및 ${NO_3}^-$는 딸기 재배용 비료에 의한 오염을 지시한다. 4월에 비하여 8월의 이온 농도의 지역별 편차가 적고 비료 등에 의한 인위적인 영향이 적어 강우에 의한 계절적 요인이 나타난다. 지하수의 수질 유형을 보면, 딴섬 중앙부는 함양 특성을 부분적으로 보이며 외곽부는 하천수와 상호 혼합되는 특성을 보여준다. Fe 및 Mn 이온 종에 대한 포화지수 계산결과, Fe의 광물종인 적철석, 침철석은 모두 과포화상태에 있어서 침전 가능한 상태이며, 능철석과 $Fe(OH)_3$, 일부는 불포화 상태로써 용존 이온상태로 존재할 가능성이 있다. Mn의 광물종인 능망간석은 불포화상태 및 과포화상태가 공존하며, 수망간석, 연망간석 및 수산화망 간석은 불포화상태로써 용존 이온 상태로 존재할 가능성이 크다.

• 공업화학
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• 제19권3호
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• pp.326-331
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• 2008

본 연구의 목표는 고체기질 표면에 Na 이온이 포함된 비양론적 인회석 코팅을 형성하는 기술을 개발하는 것이다. 나트륨염 농도가 다른 조건에서 형성된 인회석 코팅은 Na 이온이 존재하는 경우 표면 morphology, 화학적 상태 그리고 Ca/P 비율 등에 상당한 영향을 미치는 것으로 나타났다. 이러한 성질들의 변화는 Na 이온의 농도가 0.01 mM로 증가될 때까지 지속되었다. 칼슘과 인의 비율은 2.18에서 2.03 정도까지 변화되었으며, 이는 합성된 비양론적 인회석이 칼슘이 풍부한 조성을 가지고 있음을 나타내고 있다. 모든 시료들의 구조는 저결정성 구조를 갖는 것으로 나타났다. 인회석 코팅층 내에 Na 이온이 존재하는 경우, 인간 조골세포의 세포주인 SaOS-2 세포의 부착이 상당히 증가하였다. 그러나 이 세포들의 증식은 Na 이온 농도가 증가함에 따라 감소하는 것으로 나타났다. 이러한 상반된 세포반응은 SaOS-2 세포와 인회석 표면간의 작용이 세포신호전달을 포함한 세포내 기전에 상당한 변화를 초래했기 때문일 것으로 사료된다.

• 한국대기환경학회지
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• 제19권6호
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• pp.701-717
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• 2003

The objective of this study was to extensively estimate the air quality trends of the study area by surveying con-centration trends in months or seasons, after analyzing the mass concentration of PM-10 samples and the inorganic lements, ion, and total carbon in PM-10. Also, the study introduced to apply the PMF (Positive Matrix Factoriza-tion) model that is useful when absence of the source profile. Thus the model was thought to be suitable in Korea that often has few information about pollution sources. After obtaining results from the PMF modeling, the existing sources at the study area were qualitatively identified The PM-10 particles collected on quartz fiber filters by a PM-10 high-vol air sampler for 3 years (Mar. 1999∼Dec.2001) in Kyung Hee University. The 25 chemical species (Al, Mn, Ti, V, Cr, Fe, Ni, Cu, Zn, As, Se, Cd, Ba, Ce, Pb, Si, N $a^{#}$, N $H_4$$^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$, C $l^{[-10]}$ , N $O_3$$^{[-10]}$ , S $O_4$$^{2-}$, TC) were analyzed by ICP-AES, IC, and EA after executing proper pre - treatments of each sample filter. The PMF model was intensively applied to estimate the quantitative contribution of air pollution sources based on the chemical information (128 samples and 25 chemical species). Through a case study of the PMF modeling for the PM-10 aerosols. the total of 11 factors were determined. The multiple linear regression analysis between the observed PM-10 mass concentration and the estimated G matrix had been performed following the FPEAK test. Finally the regression analysis provided source profiles (scaled F matrix). So, 11 sources were qualitatively identified, such as secondary aerosol related source, soil related source, waste incineration source, field burning source, fossil fuel combustion source, industry related source, motor vehicle source, oil/coal combustion source, non-ferrous metal source, and aged sea- salt source, respectively.ively.y.

• 미생물학회지
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• 제20권4호
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• pp.210-222
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• 1982

Coliphages isolated from Han-River from September 1980 to August 1981 were classified by morphological and physiological characteristics. Effects of soil metrial on the fate of coliphage in nature were investigated. 1. The correlation coefficient between coliphage and E.coli which was host of coliphages in nature was 0.7173 (p=0.004). 2. Coliphage I isolated from Han-River of which DNA molecular weight was $27{\times}10^6$ daltons was identified as $T_1$ phage and coliphage II of which DNA molecular weight $72{\times}10^6$ daltons was classified as $T_5$ phage. 3. Soil material SW was composed of 63.65% silt and 21.92% clay. Clay was consisted of illite, kaolinite and chlorite evenly. Soil material J was composed of 68.92% silt and 11.67% clay. Clay consisted of smectite only. 4. Coliphage was absorbed to soil material J more than soil material SW, and $T_1$ coliphage was absorbed to soil material more than $T_5$ coliphage was. 5. The phage adsorption efficiency to soil material was enhanced at lower pH : the phage adsorption efficiency at pH 4 was 27 time higher than at pH 7. 6. Divalent $(Ca^{2+})\;and\;trivalention\;(Al^{3+})$ enhanced the phage adsorption efficiency to soil material from 4 to 39 and from 17 to 91 times higher than monovalent $ion(Na^+)$, respectively. 7. The concentration of organic compound was inversely related to the phage adsorption efficiency to soil. 8. Adsorption of phage onto soil material, and elution efficiency of elutants was in the order of D.D.W>tap water>river water>seawater. 9. The higher the concentration of organic compound was, the more were adsorbed phages to soil eluted. 10. Coliphages survived longer in sterile soil suspension than in nonsterile soil material suspension.

• 한국대기환경학회지
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• 제22권1호
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• pp.15-24
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• 2006

Precipitation samples were collected at Anmyeon (1997 - 2004), Uljin, and Gosan (1998 ~ 2004), the background area of the Korean Peninsula. These samples were analyzed for the concentration of 9 major ionic components ($F^{-}$,$Cl^{-}$, $NO_{3}^{-}$, $SO_{4}^{2-}$, $Na^{+}$, $NH_{4}^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$) with including a pH and an electric conductivity. Data quality for these samples was verified by ion balance and conductivity balance which are based on GAW manual for precipitation chemistry and the number of valid data at Anmyeon, Uljin, and Gosan is 249, 173, and 188, respectively. During the study period, the precipitation-weighted average pH at Anmyeon, Uljin, and Gosan was found to be 4.81, 4.87 and 4.89, respectively and each annual average pH was showed below pH 5.6 for every site. From the frequency survey on the precipitation acidity, the occurrence rate of acid rain below pH 5.6 is greater than $80\%$ for every site. Particularly, the highest occurrence rate for strong acid rain below pH 4.5 was found at Anmyeon, $32.1\%$, compared with other sites ($10.4\%$ at Uljin, $15.4\%$ at Gosan). That's because acidifying species (nss-$SO_{4}^{2-}$, $NO_{3}^{-}$) are remarkably high concentration at Anmyeon.

• 한국환경보건학회지
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• 제19권2호
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• pp.46-54
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• 1993

This study was carried out on the stabilized/solidified treatment for the reducing leachability of hazardous heavy metals copper, lead, chromium and cadmium in the hazardous sludge which treated to be unleached heavy metals by sodium diethyl dithiocarbamate. Cement matrix was analyzed for the leachability of 24 hrs and dynamic leaching test, structure and the optimum condition for the stabilization and solidification of the hazardous sludge. In 28 days of curing time the unconfined compressive strength was 21.5 kg/cm$^2$ at the ratio of portland cement (0.5)+fly ash (0.25) and 23.5 kg/cmz at the ratio of portland cement (0.5)+fly ash (0.25) + cake (0.25). High concentration of Pb, Cr and Cd in the sea water and Cu in the distilled water were leached at the dynamic leaching test. The concentration of leaching heavy metals for specimens which were tested 24 hrs were found low leachability with decreasing pH of leachant. According to dynamic leaching test, the low level of copper, lead, cadmium and chromium were leached in the cement matrix with sodium diethyl dithiocarbamate. But the effective diffusion coefficient of unleached cement matrix which was treated sodium diethyl dithiocarbamate was decreased above 2 times than that of cement matrix. The relation of leachant renewal period (Y) and cumulative fraction ion leached (X) was the following regression equations. Solidification with unleached agent. Y$_{Cu}$ = 1413752X + 247, Y$_{Pb}$ = 223501IX + 214, Y$_{Cr}$ = 8310601X - 472, Y$_{Cd}$ = 168787X + 1061 The structure of' solidified matrix with X-ray diffraction analysis was composed more Ca(OH)$_2$, Si, Mg(OH)$_2$ and Al in the unleached cement matrix than those in cement matrix.

• 한국환경농학회지
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• 제21권3호
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• pp.165-171
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• 2002

A study was conducted to investigate the seasonal changes in water quality of watershed in the Agricultural Environment Promotion Zone. Samples collected were 12 GW (ground water), 2 IW (irrigation water), 2 SW (stream water) in An-Dong City, 4 GW, 6 IW, 11 SW in Young-Yang Gun, and sampling was conducted separately during dry and rainy season. In the ground water, EC and ionic species, except pH, were higher than those in stream water, and especially $NO_3-N$ concentration exceeded the limitation of drinking water. Concentration of ions decreased as the sampling depth was far from the soil surface. During a rainy season, the concentrations of $NO_3-N$ and K in the stream water were slightly higher than those during season. COD was lower during dry season in Yong-Yang, while the trend was contrasted to An-Dong. These results suggest that ground water was polluted by fertilization and compost while streamwater was polluted by loss of soil and organic during the rainy season. Principal chemical components related with changing water quality were EC, $NO_3^-$, Ca, Mg, Na, $Cl^-$, $Cl^-$, $SO_4^-$ in ground water, whereas $NH_4-N$, K, Mg, $Cl^-$, $SO_4^-$ in stream water.

• 한국해양환경ㆍ에너지학회지
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• 제8권2호
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• pp.60-66
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• 2005

삼투압보다 높은 외부압력을 역으로 걸어주면 용매는 용질 농도가 낮은 용액쪽으로 이동하게 되는데 이 현상을 역삼투라고 한다. 역삼투 원리를 이용하여 40-70 기압의 압력구배를 구동력으로 해서 해양심층수의 담수화 적용성을 검토 조사하였다. 역삼투막의 성능에 영향을 미치는 유량과 염제거율에 관한 온도와 압력등 여러 인자들에 관하여 고찰하였다. 온도는 역삼투압 분리막의 유량에 비례하는 반면, 염제거율에 반비례하는 관계를 보이고 있다. 압력은 분리막의 유량과 염제거율에 비례하는 관계를 보였다. $Mg^{2+},\;Ca^{+2},\;Na^+,\;K^+$ 등과 같은 해수의 주성분 미네랄에 대한 역삼투 분리막의 분리특성은 해수와 같은 강전해질 용액에서 전하량이 큰 $Mg^{2+}$와 $Ca^{2+}$의 염제거율은 99% 이상으로 온도에 비례하는 관계를 보였다. 전하량이 적은 $Na^+$의 염제거율은 98%-99.5%로 2가 이온의 염제거율보다는 낮고, 전하량이 작은 $K^+$ 이온보다는 크게 나타났다. 약산이나 상온에서 기체상태나 유리상태로 존재하는 보론의 배제율은 역삼투 분리 막에서 상당히 낮게 나타나고 대부분 우리나라 먹는물의 수질 기준치를 상회한다. 그러나 보론의 배제율은 온도에 반비례하고 압력에 비례하는 관계를 이용하여 수온 $5^{\circ}C$, 압력 $70kgf/cm^2$의 운전조건에서 생산된 생산수의 보론 농도는 우리나라의 먹는물 수질 기준을 만족한다.