• Membrane Journal
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• v.22 no.3
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• pp.171-177
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• 2012

Effect of humic acid (HA), photo-oxidation and adsorption with periodic $N_2$ back-flushing was investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. It was compared and investigated with the previous result at water back-flushing in viewpoints of membrane fouling resistance ($R_f$), permeate flux (J), and total permeate volume ($V_T$). As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_T$ was the highest at HA 2 mg/L. As HA concentration increased from 2 to 10 mg/L, the membrane fouling resistance after 180 mins' operation ($R_{f,180}$) improved 0.8 times more than that of water back-flushing. Therefore, HA concentration should affect on the membrane fouling at $N_2$ back-flushing than water back-flushing. Turbidity treatment efficiencies were almost constant independent of HA concentration, but HA treatment efficiency was the maximum at HA 2 mg/L. This means that adsorption and photo-oxidation of photocatalyst beads could removed HA at HA 2 mg/L, but it was not enough at 4 mg/L. Beyond HA 6 mg/L, UF could effectively treat HA by thick cake layer on membrane surface and severe inner membrane fouling.

• Resources Recycling
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• v.28 no.4
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• pp.44-50
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• 2019

In the electric arc furnace process, the chemical energy such as the heat of oxidation reaction and the heat of carbon combustion etc. is consumed as 30% of the total input energy. In order to reduce $CO_2$ emission in EAF, it is necessary to decrease the use of electric power energy during scrap melting stage and increase the use of chemical energy. In general, when the carbon materials is individually charged into the molten steel, the carbon materials floated to the slag layer due to low density before it is dissolved in molten steel. When the concentration of carbon in the molten steel is high, the combustion energy of carbon by oxygen injection can lower the electric power energy and improve the chemical energy consumption. Therefore, an efficient charging methods of carbon material is required to increase the efficiency of carbon combustion heat. On the other hand, Al-dross, which is known as a by-product after Al smelting, includes over 25 mass% of metallic Al, and the oxidation heats of Al is lager than that of carbon. However, the recycling ratio fo Al-dross was very low and is almost landfilled. In order to effectively utilize the heats of oxidation of Al in Al-dross, it is necessary to study the application of Al-dross in the steel process. In this study, the dissolution efficiency of carbon and aluminum in molten steel was investigated by varying the reaction temperature and the mixing ratios of coke and Al-dross.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.77-77
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• 2003

산업화에 따라 각종 산업분야에서 유기 용제의 사용이 증가하게 되었고 대기오염, 수질오염 등의 상태가 심각해져가고 있는 실정이다 그러나 다양해진 오염물질을 처리하는 데 있어서 기존의 산화처리방법은 한계에 달하였고 새로운 처리공정으로 최근 고급산화법(AOP : Advanced Oxidation Process)에 대한 연구가 활발하게 진행되고 있다. 이에 본 연구에서는 대기환경 및 인체에 심각한 영향을 주는 VOCs(Voletail Organic compounds)중 BTEX(Benzene, Toluene, Ethylbenzene, Xylene)를 다양한 형태의 광촉매제를 이용하여 기상 광분해한 후 이에 대한 최적의 분해 조건과 분해율을 비교하고자 하였다. 순환식의 자체 제작한 기상광반응장치를 이용하여, CVD법으로 TiO$_2$ 입자를 알루미나 비드위에 코팅한 볼과 같은 방법으로 유리기판위에 코팅한 판상의 광촉매제 그리고 결정성이 각기 다른 루틸상과 아나타제 그리고 아나타제/루틸 혼합상의 TiO$_2$ 분말을 직접 이용하여 VOCs 농도와 종류, 광원의 종류 및 세기를 변화시켜 PID(Photo ionization Detector)방식의 순환식 VOCs 측정기를 이용하여 광분해율을 실시간으로 측정하였다.

• Journal of Industrial Technology
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• v.31 no.B
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• pp.127-132
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• 2011

Humic substances is accounted for for the largest proportion in natural organic matter(NOM) and NOM is widely distributed in varying concentration in all aquatic and soil. They can affect water quality adversely in several ways by contributing undesirable color, complexing with metal and yielding metal concentrations exceeding normal solubility. Ozonation is one of the efficient treatments for degradation of humic substances which cause some problems in water treatment. Especially, the combination of ozone and granular activated carbon was applied to degradation humic acid in aquatic system. The aim of this work to test the available of acid-treated granular activated carbon as catalyst in the ozonation of humic acid.

• Carbon letters
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• v.9 no.2
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• pp.127-130
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• 2008

This study aims to find a correlation between XRD and Raman result of the activated carbon fibers as a function of its activation degrees. La of the isotropic carbon fiber prepared by oxidation in carbon dioxide gas have been observed using laser Raman spectroscopy. The basic structural parameters of the fibers were evaluated by XRD as well, and compared with Raman result. The La of the carbon fibers were measured to be 25.5 ${\AA}$ from Raman analysis and 23.6 ${\AA}$ from XRD analysis. La of the ACFs were 23.6 ${\AA}$ and 20.4 ${\AA}$, respectively, representing less ordered through activation process. It seems that the $I_D/I_G$ of Raman spectra were related to crystallite size(La). Raman spectroscopy has demonstrated its unique ability to detect structural changes during the activation of the fibers. There was good correlation between the La value obtained from Raman and XRD.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.240-248
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• 2004

Recently, the customer's demands for automotive steel sheet have been diversified and sterned more. Therefore, as the tendency of auto industry light-weight, one among these requirements is the trend for high strength together with the thinness of automotive steel sheet. Because Mn added essentially in producing high strength steel sheet is bonded strongly with oxygen, the Fine oxidation layer was created at the welding face after the flash butt welding operated in entry section of pickling line. Thereby it was caused the crack or breakage of welding part in process of cold rolling. At this research, in order to protect the contact Mn with oxygen in atomosphere it was considered to fire oxygen with LNG and the related researches have been gone forward with the find out concrete and to apply them to operation.

• Journal of Surface Science and Engineering
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• v.50 no.4
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• pp.272-276
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• 2017

The response of AISI 310 type austenitic stainless steel to the novel low temperature plasma carburizing process has been investigated in this work. This grade of stainless steel shows better corrosion resistance and high temperature oxidation resistance due to its high chromium and nickel content. In this experiment, plasma carburizing was performed on AISI 310 stainless steel in a D.C. pulsed plasma ion nitriding system at different temperatures in $H_2-Ar-CH_4$ gas mixtures. The working pressure was 4 Torr (533Pa approx.) and the applied voltage was 600 V during the plasma carburizing treatment. The hardness of the samples was measured by using a Vickers micro hardness tester with the load of 100 g. The phase of carburized layer formed on the surface was confirmed by X-ray diffraction. The resultant carburized layer was found to be precipitation free and resulted in significantly improved hardness and corrosion resistance.

• Bulletin of the Korean Chemical Society
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• v.23 no.7
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• pp.990-994
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• 2002

Hydroxybenzothiophenes, dihydroxy-benzothiophenes, and benzothiophenedione were identified as inter-mediates of benzothiophene (BT) exposed to ultrasonic irradiation. It is proposed that benzothiophene is oxidized by OH radical to sequentially for m hydroxybenzothiophenes, dihydroxybenzothiophenes, and benzothiophenedione. Benzothiophene is decomposed rapidly following pseudo-first-order kinetics in a first-order manner by ultrasonic irradiation in aqueous solution. The toxicity of sonochemically treated solutions was checked by E. coli and a less inhibition in bacterial respiration was observed from the 120-min treated benzothiophene sample than from the untreated benzothiophene sample. Also evolution of carbon dioxide and sulfite was observed during ultrasonic reaction. A pathway for ultrasonic decomposition of benzothiophene in aqueous solution is proposed.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.595-596
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• 2006

A novel Si via structure is suggested and fabricated for 3D MEMS package using the doped silicon as an interconnection material. Oxide isolations which define Si via are formed simultaneously when fabricating the MEMS structure by using DRIE and oxidation. Silicon Direct Bonding Multi-stacking process is used for stacked package, which consists of a substrate, MEMS structure layer and a cover layer. The bonded wafers are thinned by lapping and polishing. A via with the size of $20{\mu}m$ is fabricated and the electrical and mechanical characteristics of via are under testing.

• Journal of Surface Science and Engineering
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• v.33 no.4
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• pp.241-250
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• 2000

Popcorn cracking phenomena frequently occur in thin plastic packages during the solder reflow process, which are definitely affected by poor adhesion of Cu-based leadframe to epoxy molding compounds (EMCs). In the present work, in order to enhance the adhesion strength, a brown-oxide treatment on the Cu-based leadframe was carried out and the adhesion strength of leadframe/EMC interface was measured in terms of fracture toughness by using sandwiched double-cantilever beam (SDCB) specimens. After the adhesion tests, fracture surfaces were analyzed by SEM, AES, EDS and AFM to make the failure path clear. Results showed that failure path was closely related to the oxidation time and the interfacial fracture toughness.