• Journal of Conservation Science
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• v.30 no.1
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• pp.1-11
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• 2014

Stabilization of iron artifacts is focused on desalination than corrosion inhibitors. However artifacts are not condition of desalination treatment must be applied to corrosion inhibitors. But iron artifacts is not representative of inhibitors which drug is most effective qualities have not been identified. Therefore in this study validates the effectiveness of existing inhibitors and its purpose is to suggest corrosion inhibitors for iron artifacts. In this study, Comparative experiment of corrosion inhibitors is selected BTA, DAN and MEA, TEA. This study was studied using Corrosion resistance test, Contact angle, XPS. As a result, all the samples treated with corrosion inhibitors was formed hydrophobic coating and was rising corrosion resistance. Also, the concentration of corrosion inhibitors was 3% better than 0.3%. BTA in the XPS experiment, the corrosive material to block the CH bond of the peak concentration was highly. This is considered corrosion potential is very high to see out the effect in the polarization experiment. Ethanolamine was superior to the MEA rather than in the TEA. MEA is likely to be appropriate in an outdoor iron artifacts seem to be suitable as corrosion inhibitors.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.127-132
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• 2014

$Y_2O_3$-BN ceramic composites were fabricated from the slurries of yttria powder with average particle size of 3~10 ${\mu}m$. The slurry was fabricated by mixing PVA binder, NaOH for Ph control, PEG, BN powder and $Y_2O_3$ powder. The mixed $Y_2O_3$ powders were obtained by spray drying process from the slurry. The $Y_2O_3$-BN composite specimen was shaped in size of ${\O}14mm$ and then sintered at $1550^{\circ}C$ and $1600^{\circ}C$, respectively. The characteristics, microstructure, purities, densities, bulk resistance, thermal expansion, hardness and plasma resistance of the $Y_2O_3$-BN composites were investigated with the function of BN contents and sintering temperature.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.452-457
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• 2008

분말 TiO$_2$를 코팅한 전극은 전기저항으로 인해 0.5 A 이상의 전류를 인가할 수 없었으며, 1 A를 적용하였을 때 60분의 반응시간 후 최종 RhB 농도를 측정한 결과 Ru/Ti 전극의 RhB 농도 감소 가장 큰 것으로 나타났고, Ru/Ti > Ti > SG-TiO$_2$ > Th-TiO$_2$로 나타났다. 전기분해 공정만 적용한 경우 RhB 농도 감소의 순서는 Ru/Ti = Ti > SG-TiO$_2$ > Th-TiO$_2$ 전극의 순서로 나타났다. UV만 적용한 경우 RhB 제거는 작았으며, Ti와 Ru/Ti 전극은 UV만 적용한 경우와 RhB 제거농도가 비슷하였는데 이는 전극 표면에서 광촉매 반응이 일어나지 않는다는 것을 의미한다. 반면 TiO$_2$를 전극 표면에 형성하거나 코팅한 전극은 UV만 적용한 경우보다 RhB 농도가 낮게 나타났고, TiO$_2$가 형성되거나 코팅된 전극은 P-TiO$_2$ > Th-TiO$_2$ > SG-TiO$_2$의 순서로 나타났으나 차이는 크지 않았다. 광전기촉매 공정에서 시너지 효과가 거의 없는 것은 전극 표면에 코팅되거나 형성된 TiO$_2$의 양이 적고 광촉매 반응에 의한 분해 정도가 낮아 전자-정공의 재결합 감소효과가 적기 때문인 것으로 사료되었다. Th-TiO$_2$와 SG-TiO$_2$ 전극의 경우 전해질로 Na$_2$SO$_4$를 사용한 경우의 RhB 농도가 NaCl을 사용한 경우보다 RhB 낮게 나타났으나, Ti와 Ru/Ti 전극의 경우는 반대 현상이 나타났다. 이와 같은 결과는 광촉매 반응이 높은 Th-TiO$_2$와 SG-TiO$_2$ 전극에서의 Cl$^-$의 광촉매 반응 저해현상이 높게 나타났기 때문이라고 사료되었다. 반면 DSA 전극인 Ti와 Ru/Ti 전극의 경우 광촉매 반응이 거의 나타나지 않기 때문에 주반응인 전기분해 반응에서의 촉진 반응이 지배적이기 때문에 Th-TiO$_2$와 SG-TiO$_2$ 전극과는 정 반대의 현상이 나타났다고 사료되었다. 전기/UV 공정에서는 최적 전류는 0.75 A, NaCl 투입량은 0.5 g/L로 나타났으며, 최적 UV램프 전력은 16 W인 것으로 나타났다.

• Resources Recycling
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• v.24 no.3
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• pp.66-75
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• 2015

The flexural performance of amorphous steel fibers having environmental and economy benefits due to relatively short manufacturing process were evaluated as well as that of hooked steel fibers by varing fiber length and volume fraction. Fiber lengths were 10 mm, 20 mm, 30 mm and fiber volume fractions were varied from 0.3% to 1.2%. Test results with flexural performance showed that mixing design needs to be careful because of relatively high volume of amorphous steel fiber compared to hooked steel fibers. High flexural strength was obtained from both longer fiber length and higher volume fraction. Residual strength and toughness of amorphous steel fiber were similar to that of hooked steel fiber, even though rapid dropping of applied load right after concrete matrix breaking. It can be judged that relatively high ability of energy dissipation around first cracking area relatively overcome rapid dropping of loading.

• Journal of the Korean Magnetics Society
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• v.12 no.2
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• pp.51-56
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• 2002

Permalloy thin films fabricated by rf magnetron sputtering showed the excellent magnetic properties, i.e., an effective permeability of over 2000 at 1$\mu\textrm{m}$ thick up to 10 MHz, a saturation magnetization of 10∼12 kG, a coercive force of 0.2∼1 Oe, resistivity (p) is 20 ${\mu}$$\Omega$cm. In order to control the magnetic anisotropy direction of the films in a wafer scale, two parallel Nd-Fe-B permenant mangnets were used to provide the magnetic field during the sputtering process. As a result, the anisotropy direction was successfully controlled when the two magnets were seperated with a distance of 70 mm. 3D simmulation of the magnteic fields around the wafer during sputtering were in accord with the above result.

• Journal of Life Science
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• v.21 no.1
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• pp.127-133
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• 2011

${\beta}$-Galactosidase was immobilized on chitosan bead by covalent bonding using glutaraldehyde. The characteristics of the immobilized enzyme were investigated. Maximum immobilization yield of 75% was obtained on chitosan bead. Optimum pH and temperature for the immobilized enzyme was 7.0 and $50^{\circ}C$, respectively. The immobilized enzyme showed a broader range of pH and temperature compared to a free one. A mathematical model for the operation of the immobilized enzyme in a packed-bed reactor was established and solved numerically. Under different inlet lactose concentrations and feed flow rate conditions, lactose conversion was measured in a packed-bed reactor. The experimental results of continuous operation in a packed-bed reactor were compared to theoretic results using Michaelis-Menten kinetics with competitive product inhibition and external mass transfer resistance. The model predicted the experimental data with errors less than 5%. Process optimization of continuous operation in a packed-bed reactor was also conducted. In a recirculation packed-bed operation, conversion of lactose was 97% in 3 hours. In a continuous packed-bed operation, the effect of flow rate and initial lactose concentration was investigated. Increasing flow rates and initial lactose concentration decreased the conversion of substrate.

• Journal of the Korean GEO-environmental Society
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• v.21 no.12
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• pp.35-41
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• 2020

Recently, underground spaces have been developed variously due to the concentration of the building structure in downtown area and reconstruction of the apartment. However, various problems such as differential settlement are occurring in the waterproof and reinforcement construction. In grouting method, which is frequently used for the ground reinforcement, quality control was performed by measuring the injection quantity of grouting materials and performing laboratory tests using boring samples, but it is difficult to determine whether the ground reinforcement has been performed properly during the construction stage. In order to solve this problem, a research is needed to carry out quality control by measuring electric resistivity after grouting is performed using grouting materials mixed with conductive materials. In this research, as a basic study of the new grouting method using conductive materials, uniaxial compression tests were performed using cement specimen with 0, 3, 5, 7% of carbon fiber to evaluate the effect of conductive material on the performance of grouting material. Based on the test results, the uniaxial compressive strength is increased with the mixed proportion of the carbon fiber increase. Furthermore, the carbon fiber can also affect on the early-strength of the grouting materials.

• Membrane Journal
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• v.21 no.2
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• pp.201-211
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• 2011

The effects of humic acid (HA), photo-oxidation and adsorption were investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. UF, photocatalyst, and UV radiation processes were investigated in viewpoints of membrane fouling resistance $(R_f)$, permeate flux (J), and total penneate volume $(V_{\Upsilon})$ at 2 and 4 mg/L of HA respectively. As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_{\Upsilon}$ was the highest at 2 mg/L HA. Average treatment efficiencies of turbidity decreased as increasing HA, but treatment efficiency of HA was the highest at 4 mg/L HA. It was because most of HA was removed by membrane and some HA passing through the membrane was adsorbed or photo-oxidized by photocatalyst at low HA, and therefore treated water quality was almost same at 2 and 4 mg/L HA, but feed water quality was higher at 4 mg/L. At effect experiment of photo-oxidation and adsorption, J of UF + $TiO_2$ + UV process was maintained at the highest, and ultimately $(V_{\Upsilon})$ after 180 minutes' operation was the highest. As results of comparing the treatment efficiencies of turbidity and HA, photocatalyst adsorption had more important role than photo-oxidation when HA increased from 2 to 4 mg/L.

• Membrane Journal
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• v.26 no.4
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• pp.301-309
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• 2016

The effects of water back-flushing time (BT) and photocatalyst-coated polypropylene (PP) beads were investigated in hybrid water treatment process of alumina microfiltration and the PP beads in this study, and compared with the previous study with alumina ultrafiltration membrane and the same PP beads. The BT was changed in the range of 6~30 s with fixed 10 min of back-flushing period (FT). Then, the BT effects on resistance of membrane fouling ($R_f$), permeate flux (J) and total permeate volume ($V_T$) were observed during total filtration time of 180 min. As longer BT, $R_f$ decreased and J increased dramatically; however, $V_T$ was the maximum at BT 10 s. The treatment efficiency of turbidity was high beyond 99.0%, and the BT effect was not shown. The treatment efficiency of organic matters was the highest value of 89.0% at no back-flushing (NBF), and increased as longer BT. The optimum input concentration of the PP beads was 20 g/L in the viewpoint of membrane fouling; however, the optimum PP beads of the previous study was 40 g/L. The treatment efficiency of turbidity and organic matters were the maximum at 30 g/L of the PP beads; however, those of the previous study with alumina ultrafiltration membrane and the same PP beads were the highest at 40 g/L.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.385-388
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• 2008

Recycled fine aggregate has low quality because it contains large amount of old mortar. So, its usage is limited to a lower value-add, such as the roadbed material etc. Also, alkaline water occurred from treatment process of the waste concrete is becoming the cause of environmental problem. Accordingly, this study is to develop on the high quality recycled fine aggregate produced by low speed wet abraser using sulphuric. We investigated the properties of compressive strength of the mortar which was manufactured using recycled fine aggregate containing calcined gypsum produced by earlier mentioned process. Test results indicate that concrete using recycled fine aggregate containing calcined gypsum is higher compressive strength than concrete using other sands.