• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2003년도 추계학술발표회
• /
• pp.330-333
• /
• 2003

Recently electrokinetic process is known to be a promising remediation technology for the contaminated soils with heavy metals, radionuclides, organic matters, and so on. The contaminants in electrokinetic technology are removed mainly by three mechanisms; electroosmosis, electromigration, and electrophoresis. When direct current is introduced between two electrodes planted in soil, a large amount of hydrogen ions is formed and moves from anode to cathode with the other cations contained in electrolyte. The water flow caused by tile movement of cations is called as electroosmosis. Especially for non-ionic pollutants, the electroosmotic flow(EOF) is the most important removal mechanism among them and transports contaminants from anode to cathode along the water flow. In this study, characteristics of electroosmotic flow was investigated according to the resistance state of soil. The decrease, maintenance, and increase of soil resistance could be obtained by controlling ions in soil. When the resistance of soil was decreasing or maintained, the EOF is proportional to electric current and voltage, respectively and when the resistance was increasing, the EOF is proportional to only electric current not voltage.

• Journal of Advanced Marine Engineering and Technology
• /
• 제25권2호
• /
• pp.344-350
• /
• 2001

This paper was studied on the characteristics of galvanic corrosion and its protection on heat exchanger tube plate in the sea water. In this paper, behavior of pitting corrosion of Ni-al bronze connected with Ti tube was measured af flow velocity of 0 m/s and 2.4 m/s. To protect galvanic corrosion, the protection characteristics of Ni-Al bronze connected with Ti tube by Zn-base alloys galvanic anode and hexagonal nylon insert was investigated. Main results obtained asre al follows: 1) The galvanic corrosion of Ni-Al bronze connected with Ti-tube is more active than single Ni-al bronze. 2) As the circuit resistance increase under the cathodic protection employing Zn-base alloys galvanic anode, Ni-al bronze connected with Ti tube is cathodically unpolarized. 3) The corrosion of Ni-Al bronze connected with Ti tube by nylon insert controls approximately 73% than not nylon insert.

• Journal of Advanced Marine Engineering and Technology
• /
• 제25권2호
• /
• pp.345-345
• /
• 2001

This paper was studied on the characteristics of galvanic corrosion and its protection on heat exchanger tube plate in the sea water. In this paper, behavior of pitting corrosion of Ni-al bronze connected with Ti tube was measured af flow velocity of 0 m/s and 2.4 m/s. To protect galvanic corrosion, the protection characteristics of Ni-Al bronze connected with Ti tube by Zn-base alloys galvanic anode and hexagonal nylon insert was investigated. Main results obtained asre al follows: 1) The galvanic corrosion of Ni-Al bronze connected with Ti-tube is more active than single Ni-al bronze. 2) As the circuit resistance increase under the cathodic protection employing Zn-base alloys galvanic anode, Ni-al bronze connected with Ti tube is cathodically unpolarized. 3) The corrosion of Ni-Al bronze connected with Ti tube by nylon insert controls approximately 73% than not nylon insert.

• 전기화학회지
• /
• 제9권4호
• /
• pp.151-157
• /
• 2006

A two-dimensional numerical model to study the performance of anode-supported flat-tube solid oxide fuel cell (SOFC) far the cross section of the cell in the flow direction of the fuel and air flows is developed. In this model a mass and charge balance, Maxwell-Stefan equation as well as the momentum equation by using, Darcy's law are applied in differential form. The finite element method using FEMLAB commercial software is used for meshing, discritization and solving the system of coupled differential equations. The current density distribution and fuel consumption as well as water production are analyzed. Experimental data is used to verify a predicted voltage-current density and power density versus current density to judge on the model accuracy.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.311-311
• /
• 2009

Carbon nanotubes (CNTs) belong to an ideal material for field emitters because of their superior electrical, mechanical, and chemical properties together with unique geometric features. Several applications of CNTs to field emitters have been demonstrated in electron emission devices such as field emission display (FED), backlight unit (BLU), X-ray source, etc. In this study, we fabricated a CNT cathode by using filtration processes. First, an aqueous CNT solution was prepared by ultrasonically dispersing purified single-walled CNTs (SWCNTs) in deionized water with sodium dodecyl sulfate (SDS). The aqueous CNT solution in a milliliter or even several tens of micro-litters was filtered by an alumina membrane through the vacuum filtration, and an ultra-thin CNT film was formed onto the alumina membrane. Thereafter, the alumina membrane was solvated by acetone, and the floating CNT film was easily transferred to indium-tin-oxide (ITO) glass substrate in an area defined as 1 cm with a film mask. The CNT film was subjected to an activation process with an adhesive roller, erecting the CNTs up to serve as electron emitters. In order to measure their luminance characteristics, an ITO-coated glass substrate having phosphor was employed as an anode plate. Our field emitter array (FEA) was fairly transparent unlike conventional FEAs, which enabled light to emit not only through the anode frontside but also through the cathode backside, where luminace on the cathode backside was higher than that on the anode frontside. Futhermore, we added a reflecting metal layer to cathode or anode side to enhance the luminance of light passing through the other side. In one case, the metal layer was formed onto the bottom face of the cathode substrate and reflected the light back so that light passed only through the anode substrate. In the other case, the reflecting layer coated on the anode substrate made all light go only through the cathode substrate. Among the two cases, the latter showed higher luminance than the former. This study will discuss the morphologies and field emission characteristics of CNT emitters according to the experimental parameters in fabricating the lamps emitting light on the both sides or only on the either side.

• 공업화학
• /
• 제35권4호
• /
• pp.309-315
• /
• 2024

실리콘/탄소(SiC) 복합체는 실리콘의 높은 이론 용량과 탄소 소재의 높은 전기 전도성을 동시에 만족할 수 있어 실리콘 기반 음극의 상용화를 위한 새로운 음극 소재로서 주목받고 있다. 그러나 SiC 활물질의 반복적인 부피 변화에 따른 지속적인 전해질 소모와 용량 감소는 여전히 해결되어야 하는 문제로 여겨진다. 이러한 문제를 해결하기 위해 본 연구에서는 열적 가교 반응을 통해 네트워크 구조를 형성하는 4,4'-methylenebis(cyclohexyl isocyanate) (H₁₂MDI) 기반의 수분산 폴리우레탄 바인더(HPUD)를 제안한다. 가교된 HPUD (CHPU)는 SiC 음극의 건조 공정 중 간단한 열처리를 통해서 가교제인 triglycidyl isocyanurate (TGIC)의 epoxy 고리 개환 반응을 활용하여 제조되었다. 뛰어난 기계적 특성 및 접착 특성을 가지는 CHPU 바인더를 사용한 SiC 음극은 우수한 율속 및 장기 수명 특성을 나타낼 뿐만 아니라, SiC 음극의 부피 팽창 또한 효과적으로 완화시키는 것으로 확인되었다. 본 연구 결과는 가교 구조를 가지는 환경친화적인 바인더가 다양한 실리콘 기반 음극에 활용될 수 있음을 시사한다.

• 조명전기설비학회논문지
• /
• 제17권6호
• /
• pp.77-82
• /
• 2003

본 논문에서는 강한 불평등전계를 형성시킬 수 있는 다선형전극을 강전해수 발생장치내에 설치하여 전계집중효과에 의해 발생되는 기포내의 선행방전의 형태와 기포방전이 수소이온농도와 산화환원전위반응에 미치는 영향을 검토하고자 하였다. 실험결과, 강전해수 발생장치내의 양전극측을 다선형으로 함으로써 양전극측에서 발생되는 기포내에서 비유전율 차이에 의한 기포내의 선행방전을 관찰할 수 있었다. 그리고 기포방전에 의해 발생된 이온들이 강전해수 발생장치내에 용해됨으로써 전해수의 이온농도를 증가시켰다. 이때 발생된 고농도의 이온들을 분리집속 시키고 산화환원작용을 크게 증가시켜 고농도의 강전해수를 발생시킬 수 있었다.

• Journal of Electrochemical Science and Technology
• /
• 제10권1호
• /
• pp.22-28
• /
• 2019

To maximize the oxygen evolution reaction (OER) in the electrolysis of water, nano-grade $IrO_2$ powder with a low specific surface was prepared as a catalyst for a solid polymer electrolyte (SPE) system, and a membrane electrode assembly (MEA) was prepared with a catalyst loading as low as $2mg\;cm^{-2}$ or less. The $IrO_2$ catalyst was composed of heterogeneous particles with particle sizes ranging from 20 to 70 nm, having a specific surface area of $3.8m^2g^{-1}$. The anode catalyst layer of about $5{\mu}m$ thickness was coated on the membrane (Nafion 117) for the MEA by the decal method. Scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) confirmed strong adhesion at the interface between the membrane and the catalyst electrode. Although the loading of the $IrO_2$ catalyst was as low as $1.1-1.7mg\;cm^{-2}$, the SPE cell delivered a voltage of 1.88-1.93 V at a current density of $1A\;cm^{-2}$ and operating temperature of $80^{\circ}C$. That is, it was observed that the over-potential of the cell for the oxygen evolution reaction (OER) decreased with increasing $IrO_2$ catalyst loading. The electrochemical stability of the MEA was investigated in the electrolysis of water at a current density of $1A\;cm^{-2}$ for a short time. A voltage of ~2.0 V was maintained without any remarkable deterioration of the MEA characteristics.

• 전기화학회지
• /
• 제11권3호
• /
• pp.135-140
• /
• 2008

An electrochemical generation of ozonized water was investigated by using ${\beta}-PbO_2$ as an anode and tap water as an anolyte. According to the potentiometric ozone detection which utilizes potential differences arisen from a chemical reaction of ozone and iodide, increasing tendency of ozone concentration on electrolysis time could be observed to show the maximum value of 8 ppm at an electrolysis time of 10 min. Ozone could be generated promptly even at an electrolysis time of 10 sec., suggesting great advantages of this electrochemical process in terms of simplicity and readiness that might be applied directly to practical uses including medical and/ or food industries. Influences of electrolysis on the properties and surface conditions of a $PbO_2$ electrode were also discussed from the results of cyclic voltammetry, scanning electron microscope, and X-ray diffractometer.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
• /
• pp.233-234
• /
• 2008

We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.