• 한국정보통신학회논문지
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• 제17권5호
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• pp.1055-1063
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• 2013

전자파 내성 및 전자파 장해 측정을 위한 표준 전자파 발생 장치 중 하나인 CTL cell에서 두 개의 입력 단자에 동일 신호와 역위상 신호 입력에 따른 다양한 전계와 자계 발생에 대해 살펴보았다. 기본 공진주파수 TE011이 2.20GHz인 CTL cell을 이용하여 우세 전계장과 우세 자계장 조건에서 입력 전력의 변화에 따른 전계 특성, 측정 위치에 따른 전계 특성, 주파수 변화에 따른 전계 특성을 측정하였고, 이를 이용하여 CTL cell의 측정 영역에서의 동작 특성과 공진주파수의 영향을 받지 않고 사용 가능한 주파수 대역을 살펴보았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.760-761
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• 2001

We have studied quench characteristics for current limiting elements of YBCO films in applied fields of 0 - 130 mT. The films were deposited on sapphire substrates and covered by gold top layer. The current limiting element consists of 2 mm wide YBCO stripes connected in series. The electric field - current density (E-J) measurements showed that the presence of applied magnetic fields induces uniform quench distribution for the stripes, otherwise non-uniform quenches were observed. We suggest that suppressing the critical current by increased fields due to fault current effectively forced the stripes of higher Jc(0) to quench, resulting in equalizing quench times.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.33-39
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• 2015

This paper examines the insulation performance of synthetic air and dry air. This examination was conducted based on dielectric strength in uniform and non-uniform field, electric field distribution by interior structure and defects in gas insulation switchgear (GIS) and insulation performance in different temperatures. From this review, it was found that eco-insulation gas required to possess low moisture content for power equipment in the distribution class. The results of this paper are valuable to ensure the insulation design and insulation reliability of GIS using air.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권12호
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• pp.599-606
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• 2001

In this paper, the ac breakdown characteristics of pure Ar, Kr and $N_2$ gas with gas pressure range of 58.8-137.3[kPa] under uniform and non-uniform fields were investigated, and the measured values were compared with those In Ar/$N_2$ and Kr/$N_2$ gas mixtures with pressure varying. Summarizing the experimental results, the breakdown voltages of Pure $N_2$gas, under uniform and non-uniform fields, were increased about 4.8 and 1.1 times than those of pure Ar gas, and about 4.4 and 1.2 times than those of pure Kr gas, and the ac breakdown voltage increased with the pressure increasing. The breakdown voltages of Ar/$N_2$ gas mixtures were decreased with decreasing the mixture ratio of Pure $N_2$ gas. In case of Ar(85%)/$N_2$ (15%) and Ar(70%)/$N_2$ (30%) gas mixtures comparing to the pure Ar gas, the breakdown voltages under uniform field were increased about 1.8 and 2.2 times, and under non-uniform field were increased about 1.1 and 1.3 times at the pressure of 101.3[kPa]. Also, in case of Kr(85%)/$N_2$ (15%) and Kr(70%)/$N_2$ (30%) gas mixtures comparing to the pure Kr gas, the breakdown voltages under uniform field were increased about 1.7 and 2.0 times, and under non-uniform field were increased about 1.0 and 1.2 times. Corona inception voltage of Kr(70%)/$N_2$(30%) gas mixtures under non-uniform fields were increased about 1.28 times than those of Ar(70%)/$N_2$ (30%) gas mixtures. In case of practical incandescent lamps, luminous and lifetime of Kr(70%)/$N_2$ (30%) gas mixtures were increased about 1.15 and 1.21 times than those of Ar(70%)/$N_2$ (30%) gas mixtures.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.66.2-66.2
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• 2011

A polymer-based multi-walled carbon nanotube (MWCNT) field emission device was fabricated from a composite dispersion of MWCNTs and waterborne polymethyl methacrylate (PMMA). The waterborne PMMA synthesized through the emulsion polymerization method was added to minimize the reagglomeration of dispersed MWCNTs with surfactants in water, and increase the adhesion between the and the substrate. The field emission properties of the fabricated device were optimized by adjusting the density of the emitter and the adhesion between the MWCNTs and the substrate. These were done by controlling the polymer concentration added to the MWCNT dispersion, as well as the amount of spray coating on the substrate. The results confirm the successful fabrication of a polymer-based MWCNT field emission device with a low field of 1.07 $V/{\mu}m$ and a good electric field enhancement factor of 2445. The device was fabricated by adding 0.8 mg/mL of polymer solution to the MWCNT dispersion and applying 20 cycles of spray coating. Application of this same MWCNT/polymer composite solution to a flexible polymer substrate also resulted in the successful fabrication of an electric field emission device with uniform emission and long time stability.

• 전기학회논문지
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• 제67권10호
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• pp.1322-1329
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• 2018

In this paper, the reliability test of three kinds of epoxy resin for GIS Spacer, which is a high voltage based heavy electric machine, AC electrical treeing experiments were performed. Three types of epoxy resins, Araldite B41, CT 5531 CI and B46, have slight viscosity differences. An non-uniform electric field, E = 1149.4 kV/mm, as the needle to plate electrode, a power source with a frequency of 1 kHz was applied to the tree electrode for accelerated deterioration. The treeing phenomena of the three kinds of epoxy resin all initiated, propagated, and destroyed by the branch tree. Epoxy Resin B46 was 145 times longer than B41 and 53 times longer than CT 5531CI. I think that the choice of epoxy resin is very important in choosing high voltage heavy electric machine insulation materials.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.3.2-3.2
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• 2011

In recent years, inkjet printing technology has received significant attention as a micro/nanofabrication technique for flexible printing of electronic circuits and solar cells, as well for biomaterial patterning. It eliminates the need for physical masks, causes fewer environment problems, lowers fabrication costs, and offers good layer-to-layer registration. To fulfill the requirements for use in the above applications, however, the inkjet system must meet certain criteria such as high frequency jetting, uniform droplet size, high density nozzle array, etc. Existing inkjet devices are either based on thermal bubbles or piezoelectric pumping; they have several drawbacks for flexible printing. For instance, thermal bubble jetting has limitations in terms of size and density of the nozzle array as well as the ejection frequency. Piezoelectric based devices suffer from poor pumping energy in addition to inadequate ejection frequency. Recently, an electrohydrodynamic (EHD) printing technique has been suggested and proposed as an alternative to thermal bubble or piezoelectric devices. In EHD jetting, a liquid (ink) is pumped through a nozzle and a strong electric field is applied between the nozzle and an extractor plate, which induce charges at the surfaces of the liquid meniscus. This electric field creates an electric stress that stretches the meniscus in the direction of the electric field. Once the electric field force is larger than the surface tension force, a liquid droplet is formed. An EHD inkjet head can produce droplets smaller than the size of the nozzle that produce them. Furthermore, the EHD nano-inkjet can eject high viscosity liquid through the nozzle forming tiny structures. These unique features distinguish EHD printing from conventional methods for sub-micron resolution printing. In this presentation, I will introduce the recent research results regarding the EHD nano-inkjet and the printing system, which has been applied to solar cell or thin film transistor applications.

• 한국전기전자재료학회논문지
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• 제19권1호
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• pp.75-80
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• 2006

We have fabricated a carbon nanotube field emission display(CNT-FED) panel with a 2 inch diagonal size using a screen printing method and in-situ vacuum sealing technology. The field emission properties of CNT FED panel with square-type CNT emitters. As results, the square-characterized and compared with those of the line-type CNT emitters. As results, the square-type CNT emitters showed much larger emission current and more stable I-V characteristics. Light emission started to be occurred at an electric field of 3.5 V/${\mu}m$ corresponding to the anode-cathode voltage of 700 V. The vacuum level inside of the in-situ vacuum sealed panel was obtained with $1.4 {\times} 10^{-5}$ torr. The sealed panel showed the similar I-V characteristics with the unsealed one and the uniform light emission with very high brightness at a current density of $243 {\mu}A/ cm^2$ obtained by the electric field of 10 V/${\mu}m$.

• Journal of Information Display
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• 제6권4호
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• pp.45-48
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• 2005

By applying a critical field treatment instead of the conventional surface treatments such as soft rubber roller, ion beam irradiation, adhesive taping, and laser irradiation, electron emission properties of screen-printed carbon nanotubes (CNTs) were enhanced and investigated based on the emission current-voltage characteristics through scanning electron microscopy. After nanotube emitters were activated at the applied electric-field of 2.5 V/um, the electron emission current density with good uniform emission sites reached the value of 2.13 mA/$cm^2$ , which is 400 times higher than that of the untreated sample, and the turn-on voltage decreased markedly from 700 to 460 V. In addition, enhancement of the alignment of CNTs to the vertical direction was observed.

• 한국정밀공학회지
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• 제19권12호
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• pp.134-141
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• 2002

The ER fluid can be one of efficient materials in ultraprecision polishing for optics, ceramics and semiconductors because of electrically controllable apparent viscosity. To finish small 3 dimensional structures such as the aspherical surface in optical elements, the possible arrangement of a tool, workpiece and auxiliary electrode is described. We examined the influence of the addition of a few abrasive particles on the performance of the ER fluid by measuring yield stress, and observed the behavior of abrasive particles in the ER fluid by a CCD camera, which is also theoretically predicted from the electromechanical principles of particles. On the basis of the above results, the steady flow analysis around the rotating micro tool is worked out considering the non-uniform electric field. Finally, Pyrex glass is polished using the mixture of the ER fluid and abrasive particles, and the effect of the electric field strength is evaluated.