• Title/Summary/Keyword: Collecting electrode

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Solution processed organic photodetector utilizing an interdiffused polymer/fullerene bilayer

  • Shafian, Shafidah;Jang, Yoonhee;Kim, Kyungkon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.348-348
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    • 2016
  • Low dark current (off-current) and high photo current are both essential for a solution processed organic photodetector (OPD) to achieve high photo-responsivity. Currently, most OPDs utilize a bulk heterojunction (BHJ) photo-active layer that is prepared by the one-step deposition of a polymer:fullerene blend solution. However, the BHJ structure is the main cause of the high dark current in solution processed OPDs. It is revealed that the detectivity and spectral responsivity of the OPD can be improved by utilizing a photo-active layer consisting of an interdiffused polymer/fullerene bilayer (ID-BL). This ID-BL is prepared by the sequential solution deposition (SqD) of poly(3-hexylthiophene) (P3HT) and [6,6] phenyl C61 butyric acid methyl ester (PCBM) solutions. The ID-BL OPD is found to prevent undesirable electron injection from the hole collecting electrode to the ID-BL photo-active layer resulting in a reduced dark current in the ID-BL OPD. Based on dark current and external quantum efficiency (EQE) analysis, the detectivity of the ID-BL OPD is determined to be $7.60{\times}1011$ Jones at 620 nm. This value is 3.4 times higher than that of BHJ OPDs. Furthermore, compared to BHJ OPDs, the ID-BL OPD exhibited a more consistent spectral response in the range of 400 - 660 nm.

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System of a Selenium Based X-ray Detector for Radiography (일반촬영을 위한 셀레늄 기반의 엑스선 검출기 시스템)

  • Lee, D.G.;Park, J.K.;Choi, J.Y.;Ahn, S.H.;Nam, S.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.817-820
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    • 2002
  • Amorphous selenium based flat panel detectors convert incident x-ray to electric signal directly. Flat panel detectors gain more interest real time medical x-ray imaging. TFT array and electric readout circuits are used in this paper offered by LG.Philips.LCD. Detector is based on a $1536{\times}1280$ array of a-Si TFT pixels. X-ray conversion layer(a-Se) is deposited upper TFT array with a $400{\mu}m$ by thermal deposition technology. Thickness uniformity of this layer is made of thickness control system technology$({\leq}5%)$. Each $139{\mu}m{\times}139{\mu}m$ pixel is made of thin film transistor technology, a storage capacitor and collecting electrode having geometrical fill factor of 86%. This system show dynamic performance. Imaging performance is suited for digital radiography imaging substitute by conventional radiography film system.

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The Evaluation of Multiplane-Parallel Chamber Using Crystal Plate as Ionization Medium for Therapeutic Radiation Beams

  • Young W. Vahc;Park, Kyung R.;Kim, Sookil;Chul W. Joh;Kim, Tae H.
    • Progress in Medical Physics
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    • v.9 no.1
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    • pp.29-35
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    • 1998
  • There has been necessity of an air free ionization chamber using the gold-crystal-aluminium plates, henceforth called the crystal chamber. The crystal chamber formed of parallel plates is very small in size and has more response for absorbed dose of therapeutic radiation beams. The gold plate on the crystal facing the photon and electron beam acts as an intensifier of signals and crystal plate as an ionization medium respectively. Both the copper guard ring and the aluminum collecting electrode are connected to an electrometer. Using high energy photon (6, 15 MV) and electron (9, 12, 15, 18 MeV) beams, the responses of the crystal chamber are evaluated against a PTW Farmer-type chamber at a field size of 10${\times}$10cm$^2$ and 100 cm SSD. The responses of crystal chamber for therapeutic radiation electron and photon beams are greater in magnitude by several order than Farmer. The crystal chamber has good linearity without correction factor C$\_$t,p/ with respect to the signals, a reading reproduction with good accuracy and precision less than 0.5%, and has other useful functions in measuring radiation beams.

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Development of Tubular Solid Oxide Fuel Cells with Advanced Anode Current Collection (연료극 집전체 최적화를 적용한 원통형 고체산화물 연료전지 단전지 성능 향상)

  • Kim, Wanje;Lee, Seungbok;Song, Rakhyun;Park, Seokjoo;Lim, Takhyoung;Lee, Jongwon
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.6
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    • pp.480-486
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    • 2013
  • In this study, tubular SOFC unit cell with advanced anode current collector was fabricated to improve the cell performance. First, we prepared two types of single cells having the same manufacture processes such as the same electrolyte, electrode coating condition and sintering processes. And then to compare the developed single cell performance with conventional cells, we changed the anode current collecting methods. From the impedance analysis and I-V curve analysis, the cell performance of advanced cell is much higher than that of conventional cell.

Effect of Sintering Process with Co3O4 on the Performance of LSCF-Based Cathodes for Solid Oxide Fuel Cells

  • Khurana, Sanchit;Johnson, Sean;Karimaghaloo, Alireza;Lee, Min Hwan
    • International Journal of Precision Engineering and Manufacturing-Green Technology
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    • v.5 no.5
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    • pp.637-642
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    • 2018
  • The impact of the sintering process, especially in terms of sintering temperature and sintering aid concentration, on the ohmic transport and electrode performance of $(La_{0.80}Sr_{0.20})_{0.95}CoO_{3-{\delta}}$-gadolinia-doped ceria (LSCF-GDC) cathodes is studied. The ohmic and charge-transfer kinetics exhibit a highly coupled $Co_3O_4$ concentration dependency, showing the best performances at an optimum range of 4-5 wt%. This is ascribed to small grain sizes and improved connection between particles. The addition of $Co_3O_4$ was also found to have a dominant impact on charge-transfer kinetics in the LSCF-GDC composite layer and a moderate impact on the electronic transport in the current-collecting LSCF layer. Care should be taken to avoid a formation of excessive thermal stresses between layers when adding $Co_3O_4$.

Effect of the TiO2 Nanotubes in the Photoelectrode on Efficiency of Dye-sensitized Solar Cell

  • Rahman, Md. Mahbubur;Son, Hyun-Seok;Lim, Sung-Su;Chung, Kyung-Ho;Lee, Jae-Joon
    • Journal of Electrochemical Science and Technology
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    • v.2 no.2
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    • pp.110-115
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    • 2011
  • The effect of $TiO_2$ nanotube (TNT) and nanoparticle (TNP) composite photoelectrode and the role of TNT to enhance the photo conversion efficiency in dye-sensitized solar cell (DSSC) have investigated in this study. Results demonstrated that the increase of the TNT content (1-15 %) into the electron collecting TNP film increases the open-circuit potential ($V_{oc}$) and short circuit current density ($J_{sc}$). Based on the impedance analysis, the increased $V_{oc}$ was attributed to the suppressed recombination between electrode and electrolyte or dye. Photochemical analysis revealed that the increased Jsc with the increased TNT content was due to the scattering effect and the reduced electron diffusion path of TNT. The highest $J_{sc}$ (12.6 mA/$cm^2$), Voc (711 mV) and conversion efficiency (5.9%) were obtained in the composite photoelectrode with 15% TNT. However, $J_{sc}$ and $V_{oc}$ was decreased for the case of 20% TNT, which results from the significant reduction of adsorbed dye amount and the poor attachment of the film on the fluorine-doped tin oxide (FTO). Therefore, application of this composite photoelectrode is expected to be a promising approach to improve the energy conversion efficiency of DSSC.

Operating Characteristics of Advanced 500W class Anode-supported Flat Tubular SOFC stack in KIER (500W 급 연료극 지지체 평관형 고체산화물연료전지 스택의 운전 특성)

  • Lim, Tak-Hyoung;Kim, Gwan-Yeong;Park, Jae-Layng;Song, Rak-Hyun;Lee, Seung-Bok;Shin, Dong-Ryul
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 2007.11a
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    • pp.193-198
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    • 2007
  • KIER has been developing the anode supported flat tubular SOFC stack for the intermediate temperature $(700{\sim}800^{\circ}C)$ operation. for this purpose, we have first fabricated anode supported flat tubular cells by the optimization between the current collecting method and the induction brazing process. After that we designed the compact fuel & air manifold by adopting the simulation technique to uniformly supply fuel & air gas and the unique seal & insulation method to make the more compact stack. For making stack, the prepared anode-supported flat tubular cells with effective electrode area of $90cm^2$ of connected in series with 12 modules, in which one module consists of two cells connected in parallel. The performance of stack in 3 % humidified $H_2$ and air at $800^{\circ}C$ shows maximum power of 507 W. Through these experiments, we obtained basic & advanced technology of the anode-supported flat tubular cell and established the proprietary concept of the anode-supported flat tubular SOFC stack in KIER.

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PD Signal Time-Frequency Map and PRPD Pattern Analysis of Nano SiO2 Modified Palm Oil for Transformer Insulation Applications

  • Arvind Shriram, R.K.;Chandrasekar, S.;Karthik, B.
    • Journal of Electrical Engineering and Technology
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    • v.13 no.2
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    • pp.902-910
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    • 2018
  • In recent times, development of nanofluid insulation for power transformers is a hot research topic. Many researchers reported the enhancement in dielectric characteristics of nano modified mineral oils. Considering the drawbacks of petroleum based mineral oil, it is necessary to understand the dielectric characteristics of nanofluids developed with natural ester based oils. Palm oil has better insulation characteristics comparable to mineral oil. However very few research reports is available in the area of nanofluids based on palm oil. Partial discharge (PD) is one of the major sources of insulation performance degradation of transformer oil. It is essential to understand the partial discharge(PD) characteristics by collecting huge data base of PD performance of nano modified palm oil which will increase its confidence level for power transformer application. Knowing these facts, in the present work, certain laboratory experiments have been performed on PD characteristics of nano $SiO_2$ modified palm oil at different electrode configurations. Influence of concentration of nano filler material on the PD characteristics is also studied. Partial discharge inception voltage, Phase resolved partial discharge (PRPD) pattern, PD signal time-frequency domain characteristics, PD signal equivalent timelength-bandwidth mapping, Weibull distribution statistical parameters of PRPD pattern, skewness, repetition rate and phase angle variations are evaluated at different test conditions. From the results of the experiments conducted, we came to understand that PD performance of palm oil is considerably enhanced with the addition of $nano-SiO_2$ filler at 0.01%wt and 0.05%wt concentration. Significant reduction in PD inception voltage, repetition rate, Weibull shape parameter and PD magnitude are noticed with addition of $SiO_2$ nanofillers in palm oil. These results will be useful for recommending nano modified palm oil for power transformer applications.

Relationship of the use of some fluoride containing dentifrice on the korean market to children's fluoride intake in different age groups (국내 시판 일부 불소함유치약 사용 시 연령별 어린이 불소섭취량)

  • Lee, Kyeong-Hee;Choi, Choong-Ho;Hong, Suk-Jin
    • Journal of Korean society of Dental Hygiene
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    • v.12 no.5
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    • pp.881-896
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    • 2012
  • Objectives : The purpose of this study was to examine the amount of daily fluoride intake among children using fluoride-containing dentifrice in an effort to pave the way for the selection of criteria for the development of safe dentifrice for different age groups to make a contribution to children's oral health. Methods : This study was implemented over approximately six months from May to October 2008 by recruiting subjects, asking their consent, conducting a survey, collecting samples and analyzing the collected data. The subjects in this study were preschool residents in Seoul and Gyeonggi province, who were at the western age of 2 to 5. The amount of fluoride withdrawn from their one-time toothbrushing was measured in two different ways. One was by using HMDS-facilitated modified diffusion method and fluoride ion electrode, and the other was by applying ion chromatography without the diffusion procedure. Results : The fluoride intake accounted for $46.5{\pm}19.1$ percent of the amount of fluoride used, and that percentage was statistically significantly different according to age(p<0.01). The one-time fluoride intake from dentifrice per weight(kg) was a mean of $0.009{\pm}0.006mg$. As a result of multiplying this amount by daily toothbrushing frequency, the daily fluoride intake from dentifrice per weight(kg) appeared to be $0.023{\pm}0.016mg$ on average. There was a large difference among the children in that regard, since that ranged from a low of 0.003mg to a high of 0.070mg. And age made a statistically significant difference to that(p<0.01). Conclusions : The above-mentioned findings of the study showed that the children's daily fluoride intake from dentifrice per weight was lower than the recommended daily fluoride intake from diets per weight for young children aged 1 to 12(0.05-0.07mg). However, there was a great disparity among the children in that aspect, and they are likely to take more fluoride from other things as well. Therefore it is required to prepare separate criteria for preschool and school-aged children.

Research on soil composition measurement sensor configuration and UI implementation (토양 성분 측정 센서 구성 및 UI 구현에 관한 연구)

  • Ye Eun Park;Jin Hyoung Jeong;Jae Hyun Jo;Young Yoon Chang;Sang Sik Lee
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.17 no.1
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    • pp.76-81
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    • 2024
  • Recently, agricultural methods are changing from experience-based agriculture to data-based agriculture. Changes in agricultural production due to the 4th Industrial Revolution are largely occurring in three areas: smart sensing and monitoring, smart analysis and planning, and smart control. In order to realize open-field smart agriculture, information on the physical and chemical properties of soil is essential. Conventional physicochemical measurements are conducted in a laboratory after collecting samples, which consumes a lot of cost, labor, and time, so they are quickly measured in the field. Measurement technology that can do this is urgently needed. In addition, a soil analysis system that can be carried and moved by the measurer and used in Korea's rice fields, fields, and facility houses is needed. To solve this problem, our goal is to develop and commercialize software that can collect soil samples and analyze the information. In this study, basic soil composition measurement was conducted using soil composition measurement sensors consisting of hardness measurement and electrode sensors. Through future research, we plan to develop a system that applies soil sampling using a CCD camera, ultrasonic sensor, and sampler. Therefore, we implemented a sensor and soil analysis UI that can measure and analyze the soil condition in real time, such as hardness measurement display using a load cell and moisture, PH, and EC measurement display using conductivity.