• Korean Chemical Engineering Research
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• 제40권6호
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• pp.659-663
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• 2002

에틸알코올의 첨가로 과포화가 유도되는 NaF 결정화 과정을 수정진동자를 이용하여 측정하였다. 준안정 상태의 NaF 용액에 에틸알코올을 첨가하면 NaF의 용해도가 감소하여 NaF 과포화가 형성되어 결과적으로 NaF 결정이 생성 및 성장한다. NaF 용액의 과포화에서 결정 생성 및 성장하는 변화를 감지하기 위하여 수정진동자의 금전극 표면을 염산시스테아민(cysteamine hydrochloride; 2-mercaptoethylamine hydrochloride)으로 self-assembly하여 수식하여 응용 가능성을 검토하였다. 과포화 과정을 통해 생성된 NaF 결정이 염산시스테아민 표면 위에 흡착되면 흡착된 양에 비례하여 수정진동자 주파수가 변화하기 때문에 주파수 변화를 측정함으로써 간접적으로 NaF 결정과정을 분석할 수 있었다. 알코올의 주입량을 1-5 ml로 변화시킴으로써 용액 중에 형성되는 NaF의 과포화 농도의 수준을 변화시켜 주었으며, 염산시스테아민 박막에 대한 주파수 변화를 분석함으로써 주입량에 따른 NaF 결정화 정도를 해석할 수 있었다. 이들 결과들을 통하여 수정진동자를 이용한 NaF 결정화 과정의 분석이 가능함을 알 수 있었다.

• 한국세라믹학회지
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• 제46권6호
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• pp.689-694
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• 2009

Layer-structured $Na_xCo_2O_4$ was synthesized from $Na_2CO_3\;and\;Co_3O_4$ powders. The chemical concentrations of Na and additive were controlled to enhance the thermoelectric properties over the temperature range from 400 K to 1,150 K. As a result, we obtained the maximum thermoelectric properties at a single phase region with Na content of x=1.5. When Na content was smaller than x=1.5, the thermoelectric properties was low due to formation of second phases of CoO and other oxides. Additionally, Mn was doped to improve thermoelectric properties by means of decreasing thermal conductivity. The results showed that the concentrations of both Na and Mn are all governing factors to determine the thermoelectric properties of $Na_xCo_2O_4$ system.

• Carbon letters
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• 제16권2호
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• pp.116-120
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• 2015

We investigated the adsorption of Na on graphene and graphene oxide, which are used as anode materials in sodium ion batteries, using density functional theory. The adsorption energy for Na on graphene was -0.507 eV at the hollow sites, implying that adsorption was favorable. In the case of graphene oxide, Na atoms were separately adsorbed on the epoxide and hydroxyl functional groups. The adsorption of Na on graphene oxide-epoxide (adsorption energy of -1.024 eV) was found to be stronger than the adsorption of Na on pristine graphene. However, the adsorption of Na on graphene oxide-hydroxyl resulted in the generation of NaOH as a by-product. Using density of states (DOS) calculations, we found that the DOS of the Na-adsorbed graphene was shifted down more than that of the Na-adsorbed graphene oxide-epoxide. In addition, the intensity of the DOS around the Fermi level for the Na-adsorbed graphene was higher than that for the Na-adsorbed graphene oxide-epoxide.

• 원예과학기술지
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• 제19권3호
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• pp.342-347
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• 2001

인공상토재배 시 상토종류와 해수농도가 퉁퉁마디의 생육과 무기양분흡수 경향을 알아보고 자생지 식물의 생육단계별 무기양분 흡수 변화를 알아보기 위해 실험을 실시하였다. 퉁퉁마디는 해수농도가 0, 10, 30, 90%이고 무비 및 유비의 상토조건에서 재배되었다. 식물의 초장, Na, K, Ca 농도는 식물체의 내염성과 관련성을 가지고 있었으며, 초장은 해수농도가 10, 30%에서 가장 길었다. 해수 희석농도 간에는 상토종류에 따라 다르나 해수 10%와 30% 시험구에서 양호한 값을 보였고, 황색길이와 녹색길이의 비율은 해수율이 낮을수록 황색길이가 많은 경향을 보였다. 인공상토에서 재배한 식물체는 해수농도가 높을수록 Na, Mg, Fe를 많이 흡수하는 경향이었으나 Ca, P, K 등은 오히려 감소하는 경향이었다. 해수농도가 증가할수록 Na의 농도는 증가하고 K의 농도는 감소하는 경향을 보였다. 해수의 농도가 높을수록 식물체 안에서 Na의 축적이 증가하였으며, 식물체의 Na의 흡수증가로 K/Na 비는 감소하였다. 해수농도가 낮아질수록 Na농도가 낮았다. 자생지인 갈사지역에서 자생하고 있는 퉁퉁마디의 생육시기별 무기성분 분석결과를 보면 채취시기에 따라 큰 차이를 보였는데 Na, Mg, K은 6월이 가장 높았으며 Ca, P의 농도는 9월에 가장 높았다. 그리고 4월 중의 무기성분농도가 6월과 9월에 비해 가장 낮은 결과를 보여 채취시기에 따라 무기성분이 다른 것을 알 수 있었다.

• 접착 및 계면
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• 제11권3호
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• pp.106-111
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• 2010

PEGMA macromer를 Na-MMT에 삽입한 후 MMA 및 MA 단량체와의 공중합을 행하여 PEGMA/(Na-MMT)-co-MMA/MA 나노복합재료를 합성하고 이의 특성결정을 행하였다. 제조된 나노복합재료를 XRD로 관찰한 결과, Na-MMT에 PEGMA를 삽입하였을 경우 Na-MMT 양이 증가함에 따라 Na-MMT의 실리케이트 층간거리는 증가하였다. DSC 측정으로부터 Na-MMT 첨가량이 늘어날수록 Tg는 높아지는 경향을 보였다. TGA 측정을 통하여 PEGMA/(Na-MMT)-co-MMA/MA 나노복합재료는 순수한 PEGMA-co-MMA/MA보다 열안정성이 다소 향상됨을 확인하였다.

• 한국환경농학회지
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• 제17권4호
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• pp.335-340
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• 1998

This study was conducted to determine the morphological responses of barley seedlings to NaCl stress and to investigate histological changes of cells with transmission electron microscope(TEM) after NaCl stress. Plant height and root length of 10-day old barley seedlings with NaCl stress were reduced and inhibition level was found to be more severe in the plant height than in the root length. The leaf length, leaf width and leaf area were shorter as well with NaCl stress than without NaCl stress. However, there was no difference in the number of roots between NaCl treatments. The weight of dry matter decreased at higher NaCl concentrations, especially at 100mM NaCl. The water content of shoots tend to decrease at higher NaCl concentrations, but there was no difference in the water content of roots, The reduced sugar content was greatly increase than starch. Cellulose content was higher in NaCl stressed-plant than control, and tended to decreased at higher NaCl concentrations. Lignin content also decreased NaCl stressed-plant but there was no tendency at NaCl stress concentrations. Electric conductivity of cell sap with seedlings was high with NaCl stressed-plant. Amount of cell sap gradually increased with time in the roots than in the shoots, The grana of chloroplasts was changed by 150mM NaCl concentration. The christe of mitochondria in root meristematic sells ruined in structure and cell wall of leaf and root was also ruined by NaCl stress.

• 한국재료학회지
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• 제6권5호
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• pp.504-514
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• 1996

고상반응법과 sol-gel법으로 제조된 NASICON의 상온과 25$0^{\circ}C$에서의 X선 회절 데이터를 리트벨트 분석을 행하였다. monoclinic에서 rhombohedral로 상전이가 일어나도 원자들의 변위는 매우 작았다. 이들 상간의 ZrO6 팔면체와 Si(P)O4 사면체고 구성된 골격은 다소 다르게 나타남으로 인하여 Na 이온의 자리도 변하였다. 이들 방법으로 제조된 NASICON은 Zr이 부족한 비화학양론 화학식, Na 1+x+4yZr2-xSixP3-xO12으로 표현될 수 있었다. 제조법에 따라 Na 이온들의 자리 점유율이 변화하였다. 상온에서는 Na(1)과 Na(3)자리의 자리 점유율의 합이 거의 1에 가까웠으나, 25$0^{\circ}C$에서는 Na(1)과 mid Na 자리를 단위 화학식 당 한 개를 약간 상회하는 Na 이온이 점유하였다. 상온과 25$0^{\circ}C$에서의 Na 이온의 이동 경로가 다름을 알 수 있었다. 또한 25$0^{\circ}C$에서는 Na(1)자리와 Na(2)자리 사이에 mid Na가 존재하며, 이 자리가 Na 이온의 이동에 중요한 역할을 함을 알 수 있었다.

• KSBB Journal
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• 제30권6호
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• pp.319-325
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• 2015

Arthrospira platensis (A. platensis) is one of the most explored cyanobacteria and has been studied for proteins, vitamins, pigment (chlorophyll and carotenoids) and fatty acid. In this study, we tested the effect of $NaHCO_3$ and $NaNO_3$ on the microalgae growth under photoautothrophic culture in A. platensis. As a result, cell growth and dry cell weight were increased in proportion to the $NaHCO_3$ and $NaNO_3$ concentration. Pigment (chlorophyll and carotenoids) contents of A. platensis were increased with proportion to $NaHCO_3$ concentration. But, the content of pigment (chlorophyll and carotenoids) in 100% $NaNO_3$ medium of A. platensis was the highest, 40%, 140% and 200% $NaNO_3$ medium with pigment content of A. platensis was reduced. In conditions of $NaHCO_3$ (50%) or $NaNO_3$ (40%) limitation, A. platensis could accumulate lipids to high as 1.7-fold and 1.3-fold.

• 한국작물학회지
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• 제44권1호
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• pp.4-10
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• 1999

This study was conducted to determine the effects of NaCl stress on nitrogen, ${NH_4}^+$, and ${NO_3}^-$ content of 4 barley cultivar seedlings that were cultured for 10 and 30 days with different NaCl levels (0, 50, 100, and 150 mM) contain-ing 1/4 Hoagland solutions. The sodium ion content in the shoot of barley seedlings sharply increased with an increase of NaCl concentration. After 30 days of NaCl treatment, the sodium content of the shoot at 150 mM NaCl was 27 times higher than in non-saline conditions. The sodium content in the root linearly increased with increasing NaCl concentration. Nitrogen content in the shoot linearly increased with increasing NaCl concentration, but nitrogen content in the root declined above the point where the $Na^+$ content was 3.0 mM/g $Na^+$ in the barley seedling. ${NO_3}^-$ content also decreased with increasing NaCl concentration. ${NH_4}^+$ content in the shoot decreased with NaCl condition, but its content in the root increased with NaCl condition. A positive correlation between ${NO_3}^-$ and ${NH_4}^+$ content was found in the shoot, but their relationship was negative in the root.

• 한국작물학회지
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• 제43권3호
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• pp.152-156
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• 1998

This study was conducted to elucidate the changes of photosynthetic ability and cation content in barley cultivar seedlings cultured for 10 and 30 days with different NaCl concentrations containing 1/4 Hoagland solutions. At the highest NaCl concentration, the weight of dry matter and the shoot/root ratio (S/R ratio) were decreased. Thus, shoots were affected more than roots by NaCl treatment. The S/R ratio decreased more in 'Neulssalbori' than in 'Bunong' by the NaCl treatment. The. internal $Na^+$ concentration increased greatly with the highest NaCl concentration, but $K^+$ concentration in plants decreased with the highest NaCl treatment. The $Ca^{2+}$ concentration had a small change with NaCl concentrations. Thus $Na^+$/$K^+$and $Na^+$/$Ca^{2+}$ratios increased with the highest concentration. The chlorophyll content (%/dry weight) of seedlings decreased at higher NaCl levels except for Bunong in 30 day old seedlings. The photosynthetic ability decreased only for Neulssalbori in the 10 days NaCl treatment. The stomatal conductance, and transpiration had decreased in the 10 day old seedlings, but not with 30 day old seedlings.