• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.87-96
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• 2010

The electrode material is one of the factors affecting the power production of microbial fuel cell. In this study, effects of carbon electrode material, thickness and configuration on the power density, biofilm formation and microbial community diversity of microbial fuel cell were investigated. To optimize the anode-cathode electrode assembly, seven lab-scale reactors which had various carbon electrode constructions were operated in continuous mode. Under the steady state condition, the electrode combination of graphite felt (6 mm) with hole showed the highest cell voltage of 238 mV and the coulombic efficiency of 37%. As a result of SEM analysis, the bacteria growing on surface of knitted type of carbon cloth and graphite felt electrode ncreased significantly. The change of dominant species between seeding sludge and biofilm on the surface of anode electrode, microbial analysis with PCR-DGGE showed that the dominant species of seeding sludge are quite different from those of biofilm on the surface of each anode electrode. Especially Geobacter sp., a well known electrochemical bacteria, was found as the dominant species of the electrode combination with graphite felt.

• Resources Recycling
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• v.33 no.4
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• pp.47-61
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• 2024

As a recycling technology for recovering zinc contained in large amounts in electric arc furnace dust (EAFD), the most commercialized technology in the world is the Wealz Kiln Process. The Wealz Kiln Process is a process in which components such as Zn and Pb in EAFD are reduced/volatile (endothermic reaction) in high-temperature Kiln and then re-oxidized (exothermic reaction) in the gas phase and recovered in the form of Crude zinc oxide (60wt%Zn) in the Bag Filter installed at the rear end of Kiln. In this study, an experimental Wealz kiln was produced to investigate the optimal process variable value for practical application to the recycling process of large-scale kiln on a commercial scale. Additionally, Pellets containing EAFD, reducing agents, and limestone were continuously loaded into Kiln, and the amount of input, heating temperature, and residence time were examined to obtain the optimal crude zinc oxide recovery rate. In addition, the optimal manufacturing conditions of Pellets (drum tilt angle, moisture addition, mixing time, etc.) were also investigated. In addition, referring to the SiO₂-CaO-FeO ternary system diagram, the formation behavior of a low melting point compound, a reaction product inside Kiln according to the change in the basicity of Pellet, and the reactivity (adhesion) with the castable constructed on the inner wall of Kiln were investigated. In addition, in order to quantitatively investigate the possibility of using anthracite as a substitute for Coke, a reducing agent, changes in the temperature distribution inside Kiln, where oxidation/reduction reactions occur due to an increase in the amount of anthracite, the quality of Crude zinc oxide, and the behavior of tar in anthracite were also investigated.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.39-46
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• 2011

NO oxidation is an important prerequisite step to assist the selective catalytic reduction (SCR) at low temperatures ($<200^{\circ}C$). Therefore, we conducted the lab- and bench-scales experiments appling the sodium chlorite powder ($NaClO_2(s)$) for the oxidation of NO to $NO_2$ and the carbon-based catalyst for the reduction of $NO_x$ and $SO_2$; the lab- and bench-scales experiments were conducted in laboratory and iron-ore sintering plant, respectively. In the lab-scale experiment, known concentrations of $NO_x$ (200 ppm), $SO_2$ (75 ppm), $H_2O$ (10%) and $NH_3$ (400 ppm) in 2.6 L/min were introduced into a packed-bed reactor containing $NaClO_2(s)$, then gases produced by the reaction with $NaClO_2(s)$ were fed into the carbon-based catalyst (space velocity = $2,000hr^{-1}$) at $130^{\circ}C$. In the bench-scale experiment, flue gases of $50Nm^3/hr$ containing 120 ppm NO and 150 ppm $SO_2$ were taken out from the duct of iron-ore sintering plant, then introduced into the flow reactor; $NaClO_2(s)$ were injected into the flow reactor using a screw feeder. Gases produced by the reaction with $NaClO_2(s)$ were introduced into the carbon-based catalyst (space velocity = $1,000hr^{-1}$). Results have shown that, in both lab- and bench-scales experiments, NO was oxidized to $NO_2$ by $NaClO_2(s)$. In addition, above 90% of $NO_x$ and $SO_2$ removal were obtained at the carbon-based catalyst. These results lead us to suggest that the combination of $NaClO_2(s)$ with the carbon-based catalyst has the potential to achieve the simultaneous removal of $NO_x$ and $SO_2$ at low temperature ($<200^{\circ}C$).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.997-999
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• 2008

In this paper, viologen derivative is used as charge transfer material to develop sensors for detecting the organic pollutants which are the main reason of harbor pollution. We fabricated self-assembled monolayers of viologen derivative on gold electrode of QCM and investigated an electrochemical behavior property. We also determined electrochemical sensing property about environmental pollution materials such as bezene, phosphate and surfactant through quantitative and qualitative analysis of charge transfer using intrinsic property of viologen derivative by temperature and concentration change. From the achieved results, we can apply and develope the detecting sensors for harbor pollutants.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.258.2-258.2
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• 2015

염료감응형 태양전지(Dye-Sensitized Solar Cells; DSSC)는 공정비용과 재료가 저렴하여 차세대 태양전지로 각광받고 있다. 특히 투명한 재료를 사용하므로 flexible한 기판을 이용하여 그 적용범위가 넓다. DSSC는 상부전극인 FTO와 전해질의 접촉으로 인해 일부 FTO의 전자가 외부로 나가지 못하고 산화환원 반응에 의해 도로 전해질로 들어갈 확률이 있다. 이로 인해 효율 감소문제를 야기 할 수 있다. 이를 해결하기 위해 FTO위에 여러 물질들을 증착하거나 코팅 등의 많은 연구가 이루어져 왔다. ZnO를 DSSC로 적용한 연구는 많이 이루어졌지만 대부분 공정이 Chemical Vapor Deposition (CVD)으로 진행 되어왔다. 본 연구에서는 FTO위에 ZnO를 진공 공정에 비해 저렴하고 간단한 spin-coating으로 blocking layer를 형성하였다. 그 후 염료에서 여기 된 전자를 FTO로 전달해 주는 역할을 하는 TiO2를 doctor blade방법으로 형성하였다. ZnO는 TiO2하고 전도대와 가전자대의 에너지 준위 차이가 거의 없고, ZnO의 전자 이동도가 TiO2보다 높기 때문에 FTO로 전자를 큰 저항 없이 전달 할 수 있다. 또한 투과율이 좋아 염료까지의 빛의 투과성도 뛰어나다. ZnO blocking layer를 형성하여 FTO에서 전해질로의 전자이동을 막아주는 역할을 하여 DSSC의 performance 향상을 확인하였다. Field Emission Scanning Electron Microscope(FE-SEM)을 통해 FTO/ZnO/TiO2의 계면 및 두께를 확인하였고. DSSC의 특성 분석을 위해 I-V curve, Power conversion efficiency, Impedance spectroscopy를 측정 하였다.

• Journal of The Korean Association For Science Education
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• v.30 no.4
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• pp.389-401
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• 2010

This research investigated recognitions on outside and inside electrodes in an electric circuit supplied by a galvanic cell, through survey and interview of teachers studying in Departments of Physics Education and Chemistry Education at H University Graduate School. Physics majors' designations on outside or inside parts of electrodes in a galvanic cell were different from Chemistry majors'. Teachers who had majored in physics had difficulties on the inside electrode of a galvanic cell, while teachers who had majored in chemistry had difficulties on the outside electrode. Reasonings for designations of electrodes were attributed to direction of electric current in case of physics teachers and redox in case of chemistry teachers, respectively, which are strongly dependent on backgrounds performed in their undergraduate course.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.331-334
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• 2007

탄소나노튜브는 화학적 안정성과 고전도성을 갖는 동시에 높은 비표면적을 지니고 있다. 이와 같은 특정으로 염료감응형태양전지의 상대전극으로 사용 가능이 기대되어 지고 있으나, 아직 성공적인 연구가 발표되고 있지 않다. 많은 연구자들이 CNT 자체만으로 원하는 효과를 얻지 못하고 있기 때문에, CNT 조작(가공)을 통해 CNT 특성을 올리고자 노력하였다. 그러나 본 연구에서, 가공하지 않은 CNT powder를 이용하여 paste를 제조하고 doctro-blade법으로 코팅하여 CNT counter electrode를 제조하여 DSSC의 상대전극으로써의 적용 가능성을 조사 해 보았다. 제조된 CNT counter electrode에 대한 CNT 자체만의 전기화학적 특성을 측정하였다. 그리고 DSSC 에 직접 적용하여 전지의 광전특성을 측정하였다. 그 결과 탄소나노튜브의 고전도성 특성과 넓은 비표면적 특성에 의해 상대전극의 전해질/전극계변에서의 전해질의 산화환원 반응에 대한 촉매 작용을 향상시키고, 상대전극 표변에서의 전자전달 속도를 높여 염료감응형 태양전지의 효율을 높이는 것으로 확인되어졌다.

• Applied Biological Chemistry
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• v.37 no.4
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• pp.310-314
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• 1994

An antioxidant was isolated from pine needles. This compound was identified as 4-hydroxy-5-methyl-3[2H]-furanone on the basis of spectroscopic evidences and by the comparison with the synthetic one from the Maillard reaction of xylose and glycine. It scavenged 1,1-diphenyl-2-picrylhydrazyl free radicals more efficiently than 4-hydroxy-2,5-dimethyl-3[2H]-furanone and $3-hydroxy-2-methyl-{\gamma}-pyrone$ did. It exhibited inhibitory effects on the autoxidation of 3,4-dihydroxyphenylalanine and linolenic acid.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.227-234
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• 2004

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion(CLC) may yield great advantages of savings of energy to $CO_2$ separation and suppressing the effect on environment. In chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. The purpose of this study is to demonstrate inherent $CO_2$ separation and no NOx emission and to confirm high $CO_2$ selectivity, no side reaction (i.e., carbon deposition, hydrogen generation) by continuous reduction and oxidation experiment in a 50kWtb chemical-looping combustor. NiO/bentonite particle was used as a bed material and $CH_4$ and air were used as reacting gases for reduction and oxidation respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.394.1-394.1
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• 2014

고효율 및 낮은 구동 전압을 가지는 유기 발광소자를 제작하기 위한 많은 연구가 진행되고 있다. 고효율 및 낮은 구동전압을 가지는 p-i-n 유기발광소자는 정공수송층에 p형 무기 도펀트를 도핑하고, 전자수송층에 n형 무기 도펀트를 사용하여 제작하지만, 무기 도펀트는 높은 온도에서 증착하기 때문에 챔버 내의 다른 유기 물질들이 함께 증착되거나 유기 박막에 손상을 가져올 수 있는 단점을 가지고 있기 때문에 유기물 n형 도펀트의 경우는 연구가 필요하다. 본 연구에서는 유기 p형 도펀트인 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile과 유기 n형 도펀트인 bis (ethylenedithio)-tetrahiafulene (BEDT-TTF)를 사용하여 p-i-n 구조의 유기 발광소자를 제작하였다. 유기 n형 도펀트인 BEDT-TTF는 전자수송층 사이에서 산화-환원 반응을 통해 많은 전자를 생성하게 되고, 증가한 전자들로 인해서 Al 음극전극과 전자수송층 사이의 에너지장벽이 낮추는 역할을 하게 된다. BEDT-TTF를 도핑하지 않은 유기 발광소자보다 BEDT-TTF를 도핑하였을 때, 100 cd/m2 일때 약 2.4 V 작동 전압의 감소를 관측할 수 있었다. 이 결과는 음극전극으로부터 발광층으로 전자의 주입이 원활하게 되고, 그 결과 낮은 구동전압 및 고효율을 가지는 p-i-n 유기 발광소자를 제작할 수 있다는 것을 보여준다.