• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.04a
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• pp.83-88
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• 2011

워터스크린(이하 W/S)에 의한 화재방화시스템은 도로터널에 화재가 발생시, 공간에 수막을 사용하여 구획화하고, 열 연기의 확산을 억제하며 유해 부유입자를 세정함으로서 인간의 안전을 확보 및 구조물의 피해를 극소화 하는 시스템이다. 이 W/S에 의한 구획의 성능을 평가하기 위해, 1/2의 터널 모형에 의한 공간 내 열 성장 파악을 위한 화재 실험을 분석하였고, 그 결과, 천정 근방 온도 및 방사수열량으로서는 발열 속도의 크기, 풍속의 대소에 의하지 않고 약 80%의 저감율을 나타냈다. 또, 발생한 유해 부유입자 농도에 대해서는 약 60%, 화원 성질과 상태로서 발열 속도는 약30%의 W/S에 의한 저감 효과를 나타내었다.

• 수도
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• v.24 no.4 s.85
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• pp.39-46
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• 1997

실험실 규모의 연구를 확대한 Pilot-Plant연구는 Bromate 감소에 대한 다양한 수질 문제에 대응할 수 있었다. 이러한 연구를 통해 산성하에서 $Fe^{2+}$을 주입시 Bromate가 감소됨을 확인하였다. 그러나 이러한 반응은 느린 반응이었으며, 온도에 의존하는 반응이었다. 단독응집제로서 $Fe^{2+}$은 탁도를 증가시켰다. 따라서 탁도를 제어하기 위해 $Fe^{2+}$를 주입하였다. $Fe^{2+}$/$Fe^{3+}$응집제의 조합으로 TOC를 제거할 수 있었다. 초기 결과를 통해 이러한 공정은 매우 면밀히 추진되어야 하며, 모든 온도에서 적용될 수 없었다. 현재까지 얻어진 결과에 의하면 오존처리함으로서 발생되는 Bromate를 최소화하는 방안은 낮은 pH조건과 $Fe^{2+}$의 주입이다. 최종 처리수에서 입자상물질과 철을 최소화하기 위해서는 pH 등과 같은 조건들을 변화시켜 여과공정 이전에 잔류 $Fe^{2+}$를 산화시킬 수 있도록 초기에 최적화가 이루어 져야 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.403-407
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• 2003

This paper studies the error of pressure, particle velocity, and intensity which are distributed in a space. Errors may be amplified when other sound field variables are predicted. We theoretically derive their bias error and random error. The analysis shows that many samples do not always guarantee good results. Random error of the velocity and intensity are increased when many samples are used. The characteristics of the amplification of the random error are analyzed in terms of the sample spacing. The amplification was found to be related to the spatial differential of random noise. The numerical simulations are performed to verify theoretical results.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.217-224
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• 2011

Removal of dissolved selenium by D. michiganensis, a iron-reducing bacterium, and effects of dissolved metal elements such as iron, sulfate, and copper were investigated. Selenide that was reduced from selenite (2 mM) by D. michiganensis was gradually removed from the aqueous medium. As the reduced selenide was combined with aqueous iron, it was precipitated as a nanoparticulate iron-selenide. Sulfate and copper negatively affected the microbial selenite reduction, and the copper was especially toxic to the bacterium, inhibiting a microbial removal of dissolved selenite. These results show that it should be carefully biotreated for a selenium-contaminated site considering in situ sulfate or copper distribution and concentration. Consequently, the formation of iron-selenide by bacteria will be an important measure for preventing a long-distance migration of selenium in the subsurface environments.

• Resources Recycling
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• v.7 no.4
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• pp.43-49
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• 1998

We investigated the effects of the powder characteristics of various domestic iron oxides (${\alpha}Fe_2O_3$) on the magnetic properties of Sr-ferrites The particle size and the distribution of iron oxides were classified hy three different rerinning methods, and greatly a affected on the magn$\xi$tic prope$\pi$ies and the mmphology of Sr-ferntes. The agglomeration of Ruthner iron oxides and the large particles of Chemirite (CY) above $0.80{\mu}\textrm{m}$ were degraded the prope며es of Sr-fcrrites. The optimal magnetic prope$\pi$ies of Srt territes, showing 68.2 emu/g of saturation magnetization and 4300 Oe of intrinsic coerClvity, were achieved at the following c conditions; Chemirite (P2EP) iron oxides of $0.14{\mu}\textrm{m}$ molar ratio of 5.8. and calcination of $1150^{\circ}C$/1 hr.

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.507-513
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• 2012

This research was performed to evaluate the superparamagnetic iron oxide nanoparticles'(SPIONs) cell toxicity and to measure the radiation cell survival curve changes of SPIONs-uptake glioblastoma multiforme cells. The results could be practically used as the fundamental data to ameliorate proton beam cancer therapy, for example, providing necessary GBM treatment dose in the proton beam therapy when the therapy takes advantage of SPIONs. The assessment of the toxicological evaluation of synthesized SPIONs was accomplished by MTT assay as an in vitro experiment. The results showed no meaningful differences in the cell survival rate at the $1-100{\mu}g/ml$ SPIONs concentrations, but the cell toxicity was shown as the cell survival rate decreased up to 74.2% at the $200{\mu}g/ml$ SPIONs concentration. Then, we measured each radiation cell survival curve for U373MG cells and SPIONs-uptake U373MG cells with 0~5 Gy of proton beam irradiations. It is learned from the analysis of the experimental results that the SPION-uptake cells' radiation survival rate was more rapidly decreased as the irradiation dose increased. In conclusion we confirmed that SPIONs-uptake in U373MG cells induces cell death at the much less dose than the lethal dose of SPION-non-uptake cell. This research shows that the therapeutic efficacy of glioblastoma multiforme treatment in proton beam therapy can be improved by SPIONs targeting to the GBM cells.

• Korean Journal of Materials Research
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• v.8 no.9
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• pp.837-842
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• 1998

As the size of the integrated circuit is scaled down the importance of Si cleaning has been emphasized. One of the major concerns is abut the removal of metallic impurities such as Cu and Fe on Si surface. In this study, we intentionally contaminated Cu and Fe on the Si wafers and cleaned the wafer by cleaning splits of the chemical mixture of $\textrm{H}_2\textrm{O}_2$ and HF and the combination of HF treatment with UV/$\textrm{O}_3$ treatment. The contamination level was monitored by TXRF. Surface microroughness of the Si wafers was measured by AFM. The Si wafer surface was examined by SEM. AES analysis was carried out to analyze the chemical composition of Cu impurities. The amount of Cu impurities after intentional contamination was abut the level of $\textrm{10}^{14}$ atoms/$\textrm{cm}^2$. The amount of Cu was decreased down to the level of $\textrm{10}^{10}$ atoms/$\textrm{cm}^2$ by cleaning splits. The repeated treatment exhibited better Cu removal efficiency. The surface roughness caused by contamination and removal of Cu was improved by repeated treatment of the cleaning splits. Cu were adsorbed on Si surface not in a thin film type but in a particle type and its diameter was abut 100-400${\AA}$ and its height was 30-100${\AA}$. Cu was contaminated on Si surface by chemical adsorption. In the case of Fe the contamination level was $\textrm{10}^{13}$ atoms/$\textrm{cm}^2$ and showed similar results of above Cu cleaning. Fe was contaminated on Si surface by physical adsorption and as a particle type.

• Journal of Life Science
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• v.21 no.3
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• pp.444-450
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• 2011

Perchlorate ($ClO_4^-$) is a contaminant found in surface water and soil/ground water. Autotrophic perchlorate-reducing bacteria (PRB) use hydrogen gas ($H_2$) as an electron donor to remove perchlorate. Since iron corrosion can produce $H_2$, feasibility of autotrophic perchlorate-removal using zero-valent iron (ZVI) was examined in this study using activated sludge that is easily available from a wastewater treatment plant. Batch test showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of ZVI. The perchlorate biodegradation was confirmed by molar yield of $Cl^-$ as perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of iron particles used for the autotrophic perchlorate-removal, suggesting that iron particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of biofilm sample obtained from the ZVI-added enrichment culture used for $ClO_4^-$-degradation. A major band of the biofilm sample was most closely related to the class Clostridia.

• Journal of the Korean Chemical Society
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• v.50 no.6
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• pp.464-470
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• 2006

the coricosteroid drug dexamethasone is an efficacious antiinflammatory drug, it is difficult to formulate in an injectable formulation due to its poor aqueous solubility. A lipid-based nanosphere formulation containing dexamethasone was designed for solubilization of the drug in aqueous solution and sustained release of the drug from the nanosphere. The lipid nanospheres, composed of phospholipid, cholesterol and cationic lipid, were prepared by self emulsification-solvent diffusion method followed by diafiltration. Physicochemical characteristics such as mean particle diameter, zeta potential and drug loading efficiency of the lipid nanospheres were investigated according to the variation of either the kind of lipid or the lipid composition. The lipid nanospheres had a mean diameter 80-120 nm and dexamethasone loading efficiency of greater than 80%. The drug loading efficiency increased with the increase of the length of aliphatic chain attached to the phospholipid. However, the drug loading efficiency was inversely proportional to the increase of cholesterol content in the lipid composition. The lipid nanosphere could not be prepared without the use of cationic lipid and the drug loading efficiency was proportional to the increase of cationic lipid content. The lipid nanospheres containing dexamethasone are a promising novel drug carrier for an injectable formulation of the poorly water-soluble drugs.

• 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.