• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.5
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• pp.533-538
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• 2012

In this study, we used an $O_2$-sensitive luminescent dye to measure the $O_2$ concentration of culture media around HeLa cells cultured in a microchannel. $[Ru(bpy)_3]^{2+}$, which dissolves easily in water and which has no phototoxic effect, was used as the $O_2$-sensitive dye. The ratiometric sensing method was applied by introducing calcein as the $O_2$-insensitive dye, in order to overcome the disadvantages of intensity-based sensing. By performing calibration with an amperometric $O_2$ sensor, we could calculate the exact concentration of $O_2$ in the culture media. We applied this technique to measure the $O_2$ concentration around the cultured cells in the microchannel. As expected, the $O_2$ concentration gradually decreased as the cells moved farther away from the channel. This method is expected to be applicable to the investigation of hypoxia, which occurs commonly in scaffolds.

• Journal of the Korean earth science society
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• v.42 no.2
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• pp.149-163
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• 2021

In this study, the changes in ozone (O3) concentrations due to the removal of power plant emissions were analyzed using a community multi-scale air quality (CMAQ) model. Two different CMAQ model simulations, one considering the emissions from the Hadong power plant and one without considering the emissions, were conducted to investigate the effect of the emissions on the changes in the O3 concentrations in the surrounding areas. Subsequently, the CMAQ simulations exhibited an increase in the O3 concentration (25.24%) despite a decrease in the NOx (-18.87%) and volatile organic carbon (VOC, -11.27%) concentrations, which are major O3 precursors. The changes in the NO and O3 concentrations due to the removal of power plant emissions presented a strong negative correlation (r= -0.72). This indicated that the increase in the O3 concentration was mainly attributed to the significantly decreased NO concentration, thus, mitigating the O3 titration reaction (NO+O3→NO2+O2). Additionally, due to the VOC-limited (i.e., NOx-saturated) conditions in the study region, NO affected the O3 concentration, indicating that the O3 concentrations in a particular region are not only proportional to the increase or decrease in emissions. Therefore, an in-depth understanding of the chemical O3 production and loss in a particular region is necessary to accurately evaluate the effect of emission control on the changes in the O3 concentration.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.460-464
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• 2007

개구리밥, 생이가래, 은행이끼, 수련, 부들 등 5종의 식물을 대상으로 카드뮴 $(Cd^{2+})$의 농도를 달리하여 처리한 후 시간별로 식물의 광합성효율을 분석하였다. 그 결과, 개구리밥, 생이가래, 은행이끼, 부들 등 4종은 카드뮴에 민감한 것으로 조사되었고, 수련은 다른 식물종에 비해 덜 민감한 것으로 나타났다. O-J-I-P 곡선의 패턴을 살펴보면, 종에 따라 다소의 차이는 있으나 개구리밥, 생이가래, 은행이끼, 부들 등 4종의 식물은 카드뮴 농도가 증가할 수록 J, I, P값이 크게 감소하는 것을 볼 수 있었다. 특히 P-단계의 감소는 개구리밥에서 현저하게 나타나 다른 3종 보다 카드뮴에 민감한 것으로 보인다. 광계II의 광합성효율(Fv/Fm) 변화양상을 보면, 개구리밥과 생이가래는 카드뮴 농도가 50uM 이상에서는 배양 1일부터 Fv/Fm값이 급격하게 감소하였으며, 은행이끼와 부들은 3일 이후부터 50uM 이상의 카드뮴 농도하에서 Fv/Fm값이 감소하였다. 수련은 큰 변화를 보이지 않았다.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.102-102
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• 2000

최근 자동차 배기 가스 유출에 의한 환경문제가 심각하게 대두되고 있고, 이에 따라 그 중 NOx, SOx 등의 유해가스 검출을 위한 센서 개발이 강력히 요구되고 있다. 본 실험은 자동차에서 배출되는 NO 가스에 대한 민감한 센서 제작을 목적으로 In2O3 박막을 성장시켜 그 특성을 측정하였고, NO 가스에 대한 민감도를 증가시키기 위해 7 ~32 정도의 초박막 Co 촉매를 증착하여 NO 감도에 미치는 현상을 조사하였다. In2O3 2˝ target(순도 99.99%)을 사용하여 RF power와 Ar/O2의 비를 변화시켜가면서 상온에서 알루미나 기판위에 In2O3 박막 성장시켰다. 박막을 성장시킨 후 10$0^{\circ}C$에서 5$0^{\circ}C$까지 온도를 변화시키면서 공기 중에서 열처리를 하였다. In2O3 박막의 결정성은 XRD를 이용하여 측정하였고 표면 특성을 알아보기 위해 AFM과 SEM 측정을 하였다. XRD 분석결과 상온에서부터 50$0^{\circ}C$까지 회절 peck의 강도차이는 있었지만 모든 시편에서 In2O3 박막이 cubic 구조로 성장함을 알 수 있었다. 100ppm 농도 NO 가스에 대한 센서 소자의 감도를 20$0^{\circ}C$~40$0^{\circ}C$ 온도 영역에서 측정하였다. 순수한 In2O3 의 경우 감도(S=Ra/Rg)는 25$0^{\circ}C$에서 S 6 정도로 가장 좋았다. 반면에 Co 촉매를 표면에 흡착시킨 경우 20$0^{\circ}C$~25$0^{\circ}C$ 부근에서 반응속도가 매우 빨라지고, 150 정도 Co를 흡착시킨 센서의 경우 S 14 로 감도가 매우 향상됨을 알 수 있었다.

• Economic and Environmental Geology
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• v.48 no.3
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• pp.261-271
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• 2015

Toxicity results of metals, nanoparticles (NPs), and soils contaminated with metals were introduced on this review. Following methods were used: seed germination, bioluminescence, enzyme activity, and mutation. In general, different sensitivities were observed, depending on types of bioassays and pollutants. Among tested seeds, sensitivities of Lactucus and Raphanus were greater than others. Of single metal exposure, effect by As(III) was greater than others, and high revertant mutation ratio (5.1) was observed at 1 mg/L arsenite, indicating high mutagenicity. No general pattern was observed on the effect of metal mixture, but synergistic effect was observed with seeds. In case of soils, no correlation was observed between total metal contents and toxicity. Toxicity of NPs was observed as follows: CuO > ZnO > NiO > $TiO_2$, $Fe_2O_3$, $Co_3O_4$. Especially, no considerable effects were observed by $TiO_2$, $Fe_2O_3$, and $Co_3O_4$ under tested concentration (max. 1,000 mg/L). The evaluation results of interactive toxic effects using various bioassays may comprise a useful tool for the bioassessment of various environmental pollutants.

• Clean Technology
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• v.21 no.1
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• pp.39-44
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• 2015

This study investigated the effects of six metal oxide nanoparticles (NPs: CuO, NiO, TiO₂, Fe₂O₃, Co₃O₄, ZnO) on seed germination and germination index (G.I) for five types of seeds: Brassica napus L., Malva verticillata L., Brassica olercea L., Brassica campestris L., Daucus carota L. NPs of CuO, ZnO, NiO show significant toxicity impacts on seed activities [CuO (6-27 mg/L), ZnO (16-86 mg/L), NiO (48-112 mg/L)], while no significant effects were observed at > 1000 mg/L of TiO₂, Fe₂O₃, Co₃O₄. Tested five types of seed showed different sensitivities on seed germination and root activity, especially on NPs of CuO, ZnO, NiO. Malva verticillata L. seed was highly sensitive to toxic metal oxide NPs and showed following EC₅₀s : CuO 5.5 mg/L, ZnO 16.4 mg/L, NiO 53.4 mg/L. Mostly following order of toxicity was observed, CuO > ZnO > NiO > Fe₂O₃ ≈ Co₃O₄ ≈ TiO₂, where slightly different toxicity order was observed for carrot, showing CuO > NiO ≈ ZnO > Fe₂O₃ ≈ Co₃O₄ ≈ TiO₂.

• Korean Journal Plant Pathology
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• v.11 no.2
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• pp.107-115
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• 1995

들깨 '수원25호', 담배 'L8', 'KF109'와 'NC82', 시금치 '입추'와 나팔꽃을 생장혼경조절이 가능한 대기오염원 노출상에서 SO? 140ppb/시간 또는 O? 150ppb/시간의 농도로 하루 24시간 10일 동안 노출시킨 결과 '수원25호' 들깨와 담배 'L8'은 SO?에 민감한 반면, 담배 'L8'과 나팔꽃은 오존에 아주 민감한 것으로 판명되었다. 위의 농도에서 가시적 피해가 조사식물의 50%에서 발생하는 병반발생빈도 50%(SF?)를 기준으로 설정한 한계노출시간 조사에서 오존에 대한 한계 노출시간은 담배 'L8'의 경우 24시간, 나팔꽃의 경우 72시간, 담배 'NC82'와 'KF109'의 경우 144시간 내외, 시금치의 경우 216시간으로 추정되었으며, SO?에 대한 한계노출시간은 담배 'L8'의 240시간을 제외하고는 모든 식물에서 240시간 이상으로 추정되었다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.5
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• pp.46-50
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• 1978

Three types of SnO2 based semiconductor gas sensors sensitive to propane, alcohol, carbon monoidxe and acetone have been fabricated. Adding about 0.3wt.% PdCl2 or SrCO3 to SnO2 improved the sentivity. The devices were tired for one hour in air in the temperarure range of $600^{\circ}C$ to 1, 00$0^{\circ}C$. An electrical warning system using the fabricated sensors is suggested.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.6
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• pp.396-401
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• 2014

Nanomaterials have been widely used in many fields. This study investigates the effects of metal oxide nanoparticles (CuO, NiO, $TiO_2$, $Fe_2O_3$, $Co_3O_4$, ZnO) on germination and germination index (G.I.) of seeds, Lactuca and Raphanus. Under aqueous exposure, CuO on Lactuca shows the most significant impacts on activities compared to others, showing $EC_{50s}$ for germination and G.I. as 0.46 mg/L and 0.37%, respectively. The effects of nanoparticle phytotoxicity on seed Lactuca was much higher than that of Raphanus. In general, the toxicities on seed germination and germination index were as following orders : CuO > ZnO > NiO ${\gg}$ $TiO_2$, $Fe_2O_3$, $Co_3O_4$. No measurable inhibition was observed at 1,000 mg/L (maximum exposure concentration) of $TiO_2$, $Fe_2O_3$, $Co_3O_4$.

• Journal of Aquaculture
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• v.16 no.2
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• pp.118-123
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• 2003

This study was conducted to investigate the disinfection effects of chlorine dioxide ($ClO_2$) on 4 fish pathogenic bacteria (Vibrio anguillarum, Edwardsiella tarda, Streptococcus sp. and Staphylococcus sp.) isolated from infected olive flounders. The bacteria were exposed to different concentrations of ClO$_2$ (0.129, 0.246 and 0.455 ppm) and response times (0.5, 1, 3, 5 and 10 min), and then were incubated for 12 hr. The effective disinfection concentrations of $ClO_2$ against experimental bacteria by $ClO_2$ for 0.5 min were observed with 0.455 ppm for Staphylococcus sp., 0.246 ppm for V. anguillarum and E. tarda, and 0.129 ppm for Streptococcus sp., respectively. The duration of exposure at low concentration of $ClO_2$ increased for the disinfectant ability to experimental bacteria.