• Title/Summary/Keyword: Space charge layer

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Photovoltaic effect in $\beta$-carotene glass ($\beta$-carotene glass의 광기전력효과)

  • 김의훈
    • 전기의세계
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    • v.20 no.4
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    • pp.23-30
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    • 1971
  • The photovoltaic behaviors ahve been observed with a sandwich-type cell, consisting of a junction between .betha.-carotene and stannic oxide conducting layer to provide a junction electrode. In the stannic oxide and .betha.-carotene junction it was found that its electromotive forse decreased to a value smaller than the original one. This is due to a space charge formation. Photovoltage reached approximately 40mV with an irradiation energy of 250Kcal/M$^{2}$hr. It appeared that a magnitude of the photovoltaic response was proportional to the logarithm of irradiance. The time constant of the photovoltaic effect was shown to be approximately 0.7 sec. The wavelength dependence of the photovoltaic behavior was very anomalous. It is assumed that such an anomalous photoresponse depends on a internal capacitance due to some bubble during process to make a cell.

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The Dielectric Properties of BaTi $O_3$ by Additive Material (첨가제에 의한 BaTi $O_3$의 유전특성)

  • 홍경진;정우성;민용기;김태성
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.11a
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    • pp.413-416
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    • 1996
  • The ceramic dielectrics were fabricated by mixing of Mn $O_2$ and ZnO at (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_3$ and studied for dielectric relaxation characteristics. The dielectric relaxation time was increased by space charge polarization of palaelectric layer at the low temperature and frequency but it was decreased by Interface polarization at the high temperature and frequency. The remnant polarization and coercive field of ceramic dielectrics was decreased by rising temperature.ure.

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Expansion of the equilibrium constants for the temperature range of 300K to 20,000K

  • Kim, Jae Gang
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.4
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    • pp.455-466
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    • 2016
  • Chemical-kinetic parameters of the equilibrium constants to evaluate the reverse rate coefficients in the shock layer of a blunt body and the expanding flows are derived for the temperature range from 300 K to 20,000 K. The expanded equilibrium constants for the chemical reactions of the dissociation, ionization, associative ionization, and neutral and charge exchange reactions of the atmospheric species and carbon materials are proposed in the present work. In evaluating the equilibrium constants, the inter-nuclear potential energies of the molecular species are calculated by the analytical potential function of the Hulburt-Hirschfelder model, and the parameters of the analytical model are determined from the semi-classically calculated RKR potentials. The electronic states and energies of the atoms are calculated by the electronic energy grouping model, and the rovibrational states and energies of each electronic states of the molecules are evaluated by the WKB method. The expanded equilibrium constants for 31 types of the reactions are provided for the best curve-fit functions, and the recombination reaction rate coefficients evaluated from the present equilibrium constants are compared with existing measured values.

An Analysis on Electrical Double Layers at the Silicon Semiconductor Interfaces Using the Zeta Potential (Zeta전위에 의한 Silicon 반도체 계면의 전기이중층 해석)

  • Chun, Jang-Ho
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.24 no.2
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    • pp.242-247
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    • 1987
  • Electrophysical phenomena at the silicon semiconductor-electrolyte solution interfaces were analyzed based on the zeta potential of the electrical double layer and microelectrophoresis. The suspensions were composed of the p or n-type silicon particles suspended in the KCI or pH buffer solutions. The approximate diameter of the prepared and sampled sioicon semiconductor pardticles was 1.5\ulcorner. The sign of the zeta poetntials of the p and n-type silicon particles in the KCl and pH buffer solution was positive. A range of electrophoretic mobilities of the p and n-type silicons in the KCl solutions was 5.5-8.9x10**-4 cm\ulcornerV-sec and 4.2-7.9x10**-4cm\ulcornerV-sec, respectively. The range of zeta potentials corresponding to the electrophoretic mobilities is 70.4-114.0mV nad 53.9-101.2mV, respectively. On the other hand, a range of electrophoretic mobilities of the p and n-type silicons in the pH buffer solutions was 1.1x10**-4-2.2x10**-3cm\ulcornerV-sec and 0-2.1x10**-3cm\ulcornerV-sec, respectively. The range of zeta potentials corresponding to the electrophoretic mobilities is 14.1-281.6mV and 0-268.8mV, respectively. The zeta potentials and electrical double layers of the doped silicon semiconductors are decisively influenced by the positively charged ions in the solutions. The maximum values of the zeta potentials in the KCl solutions appeared at a concentration of about 10-\ulcorner. The isoelectric point of the n-type silicon semiconductors appeared at about a pH 7. The effect of the space charge of the doped silicon semiconductors can be neglected compare with the effect of the surface charge.

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Analysis of temperature effects on DC parameters of AlGaAs/GaAs HBT (AlGaAs/GaAs HBT의 DC 파라미터에 미치는 온도영향의 해석)

  • 김득영;박재홍;송정근
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.12
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    • pp.39-46
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    • 1996
  • In AlGaAs/GaAs HBT the temperature dependence of DC parameters was investigated over the temperature range between 95K and 580K. The temperature dependence of DC parameters depends on the relative contribution of each of the current components suc as emitter-injection-current, base-injection-current, bulk recombination current, interface recombination curretn, thermal generation ecurrent and avalanche current due to impact ionization within the collector space charge layer in a specific temperature. In this paper we investigated the temperature effects on DC parameters such as V$_{BE,ON}$ current gain, input and output characteristics, V$_{CE, OFF}$, R$_{E}$, R$_{C}$ and analyzed the origins, and extracted the qualitativ econditions for a stable HBTs against the temperature variation. Finally, in order to keep HBTs stable with respect to the variation of temperature, the valance-band-energy-discontinuity at emitter-base heterojunction should be large enough to enhance the effect of carrier suppression at a relatively high temperature. In addition the recombination centers, especially around collector junction, should be removed and the area of emitter and collector junction should be identical as well.

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A Study on the Grain Growth and PLZT Ceramics Fabrication by Freeze Drying Method. (동결건조법에 의한 PLZT 세라믹 제조 및 결정립 성자에 관한 연구.)

  • Lee, Sung-Gap;Ryu, Ki-Won;Lee, Young-Hie
    • Proceedings of the KIEE Conference
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    • 1987.11a
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    • pp.492-495
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    • 1987
  • In this study, PLZT ceramics were fabricated by freeze-drying and normal sintering method. The compositional rate of specimen was selected 9/65/35 (La/Zr/Ti) which have good optical and dielectric properties, sintering time was varied 1, 10, 30, 40, 50, 55, 60 and 65 hr at $1250^{\circ}C$. After sintering, the optical and dielectric properties were investigated with the grain size. As the result of the experiment, freeze-dried powder appeared particle size less than 1 um. The relative dielectric constant was increased linearly with the sintering time, specimen which sintered for 65 hr had the highest value, 5780. Grain was grown with increasing time, in the case of specimen sintered for 60 hr, the grain size was 8.4 um. Transmittance was increased with the grain size. In the case of 8.4 um grain size, the transmittance was 56 %. Curie temperature was decreased linearly by the surface-layer effect of space-charge, in the case of grain size which were 1.8 um and 8.4 um, appeared at $100^{\circ}C$ and $80^{\circ}C$, respectively.

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A study on the grain growth and PLZT ceramics fabrication by freeze drying method (동결건조법에 의한 PLZT 세라믹제조 및 결정립 성정에 관한 연구)

  • 이성갑;류기원;배선기;이영희
    • Electrical & Electronic Materials
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    • v.1 no.1
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    • pp.35-43
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    • 1988
  • In this study, PLZT ceramics were fabricated by the freeze-drying and normal sintering method. The composition rate of the specimen was selected 9/65/35(La/Zr/Ti) which had good optical and dielectric properties, sintering time was varied 1, 10, 30, 50, 55, 60 and 65(hr) at 1250(.deg.C). After sintering, the optical and dielectric properties were investigated with the grain size. As the result of the experiment, the particle size of the powder prepared by freeze-drying method was less than 1(um). The relative dielectric constant was increased linearly with the sintering time and specimen sintered for 65(hr) had the highest value, 5780. Grain was grown with increasing time, in the case of specimen sintered for 60(hr), the grain size was 8.4(um). Transmittance was increased with the grain size. In the case of 8.4(um) grain size, the transmittance was 56(%). Curie temperature was decreased linearly by the surface-layer effect of space-charge. In the case of grain size, 1.8(um), 8.4(um), curie temperatures were appeared at 100(.deg.C) and 80(.deg.C), respectively.

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The Study on the Performance Characteristics due to the Degree of Superheat in $NH_3$ Refrigeration System (III) -The Comparison of Heat Exchanger Types- ($NH_3$ 냉동장치의 과열도에 관한 성능 특성 연구(III) -열교환기 타입별 비교-)

  • Lee Jong-In;Kim Yang-Hyun;Park Chan-Soo;Ha Ok-Nam
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.12
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    • pp.1132-1138
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    • 2005
  • Recently, production and use of freon substances are restrained due to depletion of ozone layer and global warming. In this aspect of environmental problems, the best solution is to use the natural refrigerant such as ammonia. Thus, this study is to find the optimal operating conditions by comparing the performance between the shell and tube type and shell and disk type heat exchangers using the ammonia refrigerant, and to verify the superiority of the shell and disk type heat exchanger that is not used in field of refrigeration and air conditioning. Finally, this study shows that the shell and disk type heat exchanger is applicable to the ammonia refrigeration system, and this system minimizes the refrigerant charge and installation space.

Electrical properties of the lower dielectrics layer of PDP required high reflectance and low dielectric constants (높은 반사율과 저유전율이 요구되는 PDP의 후면 유전체 층의 전기적 특성)

  • Kwon, Soon-Seok;Ryu, Jang-Ryeol
    • 전자공학회논문지 IE
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    • v.43 no.4
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    • pp.8-12
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    • 2006
  • In this paper, reflectance and the dielectric characteristics for $P_2O_5$-ZnO-BaO system and $SiO_2-ZnO-B_2O_3$ system have been investigated as a function of contents of $TiO_2$. The reflectance was decreased with increasing the contents of $TiO_2$ contents, and the reflectance of $P_2O_5$-ZnO-BaO system was lowered than that of $SiO_2-ZnO-B_2O_3$ system. The dielectric constant of $P_2O_5$-ZnO-BaO system was higher than $SiO_2-ZnO-B_2O_3$ system, and the dielectric constant in the both system was increased with increasing of $TiO_2$ contents. This can explained as the space charge effects. These results are could be applied to the lower dielectrics layer of PDP required high reflective ratio and breakdown strength.

Landscape Design for the Rural Village - A Case Study of Naegokri, Yeohang-myeon, Haman-gun - (조경식재를 통한 농촌마을 경관조성에 관한 연구 - 함안군 여항면 내곡리를 사례로 -)

  • Kim, Sang-Bum;Lee, Seung-Joo;Rhee, Sang-Young
    • Journal of Korean Society of Rural Planning
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    • v.14 no.1
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    • pp.59-71
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    • 2008
  • The landscape commonly refers to the appearance of the land, including its shape, texture, and colours. Among many factors contributing to the landscape, tree and plants factors playa significant role in rural landscape as a colours. Therefore the rural traditional theme village where had been designated under the rural traditional theme village since 2007 in Naegok-ri, Eohang-myeon, Haman-gun has planned to design the tree plant planning for creating a unique rural landscape. The landscape proposal for the new Rural Village in Naegokri, Yeohang-myeon, Haman-gun suggests three main strategies; 1) The riverside area and reservoir area adjoined forest was required to be prepared to offer organization waterside landscape and forest landscape through landscape planting and selecting trees i.e. able to reflect sense of the season that promote high quality values of landscape area in rural. 2) The area adjoined stable was required to strengthen the screen planting and buffer planting with multiple plant layer structure and trees of branches and leaves closeness, shrubs of beauty flowers in order to improve disamenity landscape and odours. 3) The rural traditional theme village adjoined entrance was required to open space such as multipurpose garden, specialized or themed garden which include Landmark factors and prepared to the space with the various theme and visual diversity in order to take charge of function as landmark characteristic in Naegok-ri, Eohang-myeon, Haman-gun, and so on. In conclusion, this winning principal purpose of this study is applied to basic tree plant model for sustainable rural landscape creation in rural areas by selecting beautiful landscape plants and the tree plant planning.