• 한국전기전자재료학회논문지
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• 제26권9호
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• pp.701-706
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• 2013

We have focused on the conversion efficiency of CIGS thin film solar cell prepared by co-evaporation method as well as the optimization of process condition. The total thickness of back electrode was fixed at 1 ${\mu}m$ and the structural, electric and optical properties of CIGS thin film were investigated by varying the thickness of Mo:Na bottom layer from 0 to 500 nm. From the experimental results, the content of Na was appeared as 0.28 atomic percent when the thickness of Mo:Na layer was 300 nm with compactly densified plate-shape surface morphology. From the XRD measurements, (112) plane was the strongest preferential orientation together with secondary (220) and (204) planes affecting to the crystallization. The lowest roughness and resistivity were 2.67 nm and 3.9 ${\Omega}{\cdot}cm$, respectively. In addition, very high carrier density and hole mobility were recorded. From the optimization of Mo:Na layer, we have achieved the conversion efficiency of 9.59 percent.

• Structural Monitoring and Maintenance
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• 제3권3호
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• pp.297-314
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• 2016

As the study of internal corrosion of pipeline need a large number of experiments as well as long time, so there is a need for new computational technique to expand the spectrum of the results and to save time. The present work represents a new non-destructive evaluation (NDE) technique for detecting the internal corrosion inside pipeline by evaluating the dielectric properties of steel pipe at room temperature by using electrical capacitance sensor (ECS), then predict the effect of pipeline environment temperature (${\theta}$) on the corrosion rates by designing an efficient artificial neural network (ANN) architecture. ECS consists of number of electrodes mounted on the outer surface of pipeline, the sensor shape, electrode configuration, and the number of electrodes that comprise three key elements of two dimensional capacitance sensors are illustrated. The variation in the dielectric signatures was employed to design electrical capacitance sensor (ECS) with high sensitivity to detect such defects. The rules of 24-electrode sensor parameters such as capacitance, capacitance change, and change rate of capacitance are discussed by ANSYS and MATLAB, which are combined to simulate sensor characteristic. A feed-forward neural network (FFNN) structure are applied, trained and tested to predict the finite element (FE) results of corrosion rates under room temperature, and then used the trained FFNN to predict corrosion rates at different temperature using MATLAB neural network toolbox. The FE results are in excellent agreement with an FFNN results, thus validating the accuracy and reliability of the proposed technique and leads to better understanding of the corrosion mechanism under different pipeline environmental temperature.

• 소성∙가공
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• 제14권3호
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• pp.251-256
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• 2005

3-D micro structures and micro tools were fabricated using Micro Electrical Discharge Machining (MEDM). To make micro structures, micro electrical discharge milling process was applied. During micro electrical discharge milling, electrode (tool) worn in the both axial and radial direction. To compensate tool wear which has significant influence on machining accuracy, machining path overlapping was proposed. Machining characteristics of micro electrical discharge milling was investigated in considering of depth of cut and capacitance of discharge circuit. Micro complex shaped tools were also fabricated using REDM (reverse electrical discharge machining). Sacrificial electrodes were machined through electrical discharge milling process and were used as electrode to make micro tools. Using this process several micro tools shape of 'ㄷ', 'ㅁ' and 'o' were fabricated. With these complex shaped tools, micro machining was successfully applied repeatedly.

• 수산해양기술연구
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• 제51권4호
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• pp.545-552
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• 2015

The main object of this study is to investigate the collection characteristics of an electro-static multi-staged impaction system, experimentally. The experiment is carried out to analyze the characteristics of pressure drop and collection efficiency for the present system with the experimental parameters such as the inlet velocity, stage number, applied voltage and shape of discharge electrode, etc. In results, the pressure drop is shown below $148mmH_2O$ lower than that of the conventional bag filter at inlet velocity 3.46 m/s and 5 stage. For 5 stage, the collection efficiencies are to be 97.4, 99.0% with the applied voltage 0 kV at the inlet velocity 2.07, 3.46 m/s, while 98.4, 99.9% with 40 kV of a sharp edge discharge electrode. Additionally, the present system is to be considered as an effective compact system for a removal of particulate pollutants from marine diesel engines due to much higher collection efficiency and appropriate pressure drop.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1857-1860
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• 1996

In this paper, ozonizer of neon discharge tube type( Neolamp ) by using silent discharge has been designed and manufactured. The discharge and ozone generation characteristics of Neolamp have been studied with variation of turn-on number( N ) of Neolamp, quality( Q ) and shape of external electrode. The discharge voltage is proportional to gap spacing of spiral external electrode( G ) for constant applied volatge. The discharge current is inversely proportional to G for constant applied volatge. The ozone concentration is inversely proportional to Q and G. Also, ozone concentration and generation are proportional to N. The sterilization characteristics of Escherichia coil have been obtained more than 97[%] at $1.30[mg/{\ell}]$ of liquid ozone concentration.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.390-390
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• 2000

This research is the development of a skin-type tactile sensor for service robot using PVDF film for the detection of the contact state. The Prototype of the tactile sensor which has 8$\times$8 taxels was fabricated using PVDF film In the fabrication procedure of the sensor, the electrode patterns and common electrode of the thin conductive tape were attached to the both side of the 28 micro meter thickness PVDF film using conductive adhesive. The sensor was covered with polyester film for insulation and attached to the rubber base for making stable structure. The signals of a contact pressure to the tactile sensor were sensed and processed in the DSP system in which the signals were digitized and filtered. Finally, the signals were integrated for taking the force profile. The processed signals of the output of the sensor were visualized in PC, the shape and force distribution of the contact object were obtained. The reasonable performance for the detection of contact state was verified through the experiment.

• 한국정밀공학회지
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• 제19권1호
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• pp.212-218
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• 2002

This research is the development of a distributed tactile sensor using PVDF film far the detection of the contact state. The prototype of the tactile sensor with 8$\times$8 taxels was fabricated using PVDF film and flexible circuitry. In the fabrication procedure, the electrode and the common electrode patterns are attached to the both side of the 28${\mu}m$ thickness PVDF film. The sensor is covered with polyester film for insulation. The signals of a contact pressure to the tactile sensor are sensed and processed in the DSP system in which the signals are digitalized and filtered. And the signals are integrated for taking the force profile. The processed signals of the output of the sensor are visualized to take the shape and force distribution of the contact object in personal computer. The usefulness of the sensor system is verified through the sensing examples.

• 한국안전학회지
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• 제11권3호
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• pp.81-88
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• 1996

In order to investigate the electrical properties of transformer oils for large power, the characteristics of AC and Impulse breakdown in gap length of 1.0~2.5mm and that of volume resistivity were researched in temperature range of 20~$100^{\circ}C$. An geometrical capacitance of electrode with coaxial cylindrical shape for measuring the volume resistivity was 16pF, and highmegohm meter with model no. VMG-1000 was used, and also the applied voltage were DC 100, 250 and 500V. In the dependance of breakdown characteristics due to electrode gap length, it was confirmed that breakdown voltage was nearly uniform by volume effect according to the increase of gap. In the characteristics for AC breakdown, the dielectric strength was increased to $90^{\circ}C$ but decreased over $90^{\circ}C$, and also in case of impulse breakdown, it was increased to 7$0^{\circ}C$ and at dated $70^{\circ}C$ over in temperature range. The calculated mobility of oils in the characteristics for impulse breakdown were about $10^{-5}$~$10^{-4}cm^2/V{\cdot}S$, and the value of volume resistivity was almost invariable in low temperature range, regardless of voltage by the stable thermal properties, and it indicated a peak at $50^{\circ}C$ and had a sudden change to decrease over that temperature, and also the value of volume resistivity in 250V/mm at $80^{\circ}C$ is suitable for the International electrical standards, it was confirmed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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• pp.35-38
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• 2006

As a display becomes large recently, Acquisition of high luminance and Luminance uniformity is becoming difficult in the existing CCFL or EEFL backlight system. So, study for a performance enhancement has enforced. but lamp development of flat type is asked for high luminance and a luminance uniformity security in of LCD and area anger trend ultimately. In this paper, we changed a tip shape of an electrode for production by the most suitable LCD backlight surface light source, and confirmed discharge characteristic along discharge gas pressure and voltage, and confirmed electric field distribution and discharge energy characteristic through a Maxwell 2D simulation. Therefore the discharge firing voltage characteristic showed a low characteristic than a rectangular type and round type in case of electrode which used tip of a triangle type, and displayed a discharge electric current as a same voltage was low.

• 전기학회논문지
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• 제57권4호
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• pp.635-640
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• 2008

New gas mixtures are now finding applications such as interrupting media for high-voltage circuit breakers. These mixtures consist of a high content of carbon tetrafluoride($CF_4$) added to sulfur hexafluoride($SF_6$). Nowdays $SF_6$ has been established for the use in gas insulated substations due to its high insulation withstand level and good arc quenching capability. At this paper Breakdown characteristics were investigated for $SF_6/CF_4$ mixtures when AC voltage and standard lightning impulse voltage(LI) was applied in a needle-plane electrodes. And partial discharge(PD) experiments were carried out in the test chamber which was made in needle-plane electrode. And ${\Phi}$-Q-N distribution of partial discharge signals was analyzed. The total pressure of the $SF_6/CF_4$ mixtures was varied within the range of 0.1-0.5 Mpa in the test chamber. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of $SF_6$ at positive impulse voltage and the PD inception voltage was increased slightly when pressure of $SF_6/CF_4$ Mixtures was increased. Maximum PD inception voltage is showed in 80% SF6/20%$CF_4$.