• Title/Summary/Keyword: 박막 구조물

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Design considerations and field applications on inflatable structure system to protect rapidly flooding damages in tunnel (해저터널 급속차폐를 위한 팽창구조체의 설계 및 현장적용에 대한 연구)

  • Kim, Hyeob;Kang, Si-On;Yoo, Kwang-San;Kim, Sang-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.2
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    • pp.161-177
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    • 2017
  • This paper presents the design considerations and field applications on inflatable structure system to protect rapidly flooding damages in large section tunnel. This inflatable structure system is very valuably used to protect passively and rapidly the possibilities of tunnel damages by flooding threats and unusual leakage to be occurred during and after underground infrastructure. In particular, this system should be necessary in subsea tunnel. The predominant factors in the design of inflatable structure system are the leakage and friction characteristics between the inflater and tunnel liner. The analytical and experimental studies are performed to develop the design considerations and to examine the design parameters of the inflatable structure system. The analytical solutions are developed using membrane theory to suggest the design considerations. The relative friction tests of several fabric materials are also carried out to determine the friction characteristics according to the different friction conditions between inflater and tunnel surface. The test results show that the friction coefficients in wet surface condition are about 20% lower than the values in dry surface condition. In addition, virtual design of tunnel protection system for two virtual subsea tunnel sites which is under reviewing in Korea, is carried out based on this research. It is expected that the results of this research will be very useful to understand the inflater structure design and development the technology of tunnel protection structures in the future.

Optimization of anode and electrolyte microstructure for Solid Oxide Fuel Cells (고체산화물 연료전지 연료극 및 전해질 미세구조 최적화)

  • Noh, Jong Hyeok;Myung, Jae-ha
    • Korean Chemical Engineering Research
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    • v.57 no.4
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    • pp.525-530
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    • 2019
  • The performance and stability of solid oxide fuel cells (SOFCs) depend on the microstructure of the electrode and electrolyte. In anode, porosity and pore distribution affect the active site and fuel gas transfer. In an electrolyte, density and thickness determine the ohmic resistance. To optimizing these conditions, using costly method cannot be a suitable research plan for aiming at commercialization. To solve these drawbacks, we made high performance unit cells with low cost and highly efficient ceramic processes. We selected the NiO-YSZ cermet that is a commercial anode material and used facile methods like die pressing and dip coating process. The porosity of anode was controlled by the amount of carbon black (CB) pore former from 10 wt% to 20 wt% and final sintering temperature from $1350^{\circ}C$ to $1450^{\circ}C$. To achieve a dense thin film electrolyte, the thickness and microstructure of electrolyte were controlled by changing the YSZ loading (vol%) of the slurry from 1 vol% to 5 vol. From results, we achieved the 40% porosity that is well known as an optimum value in Ni-YSZ anode, by adding 15wt% of CB and sintering at $1350^{\circ}C$. YSZ electrolyte thickness was controllable from $2{\mu}m$ to $28{\mu}m$ and dense microstructure is formed at 3vol% of YSZ loading via dip coating process. Finally, a unit cell composed of Ni-YSZ anode with 40% porosity, YSZ electrolyte with a $22{\mu}m$ thickness and LSM-YSZ cathode had a maximum power density of $1.426Wcm^{-2}$ at $800^{\circ}C$.

FABRICATION OF ULTRA THIN $IrO_2$-TOP-ELECTRODE FOR IMPROVING EMISSION CURRENT DENSITY IN MIM CATHODES (MIM 구조의 음극 전계 방출 효율 증진을 위한 $IrO_2$ 상부전극의 제조)

  • Park, Tae-Joo;Jung, Doo-Seok;Hwang, Cheol-Seong;Park, Min-Soo;Kang, Nam-Seok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.988-990
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    • 2003
  • 기존의 FED 용 MIM cathode 에 쓰이는 다층금속상부 전극을 열처리하였을 때 생기는 문제점에 대하여 살펴보았다. 먼저 열처리 후에 상부전극자체가 열변형이 일어나면서 나타나는 비저항의 증가, 표면 형상의 악화 등이 문제점으로 나타났고, 여기에 하부전극의 변형이 이러한 현상을 더욱 악화시키는 것을 확인할 수 있었다. 특히, 상부전극의 경우 그 두께가 극히 얇아 열변형이 매우 취약한 탓에 대체 물질의 개발이 시급하였다. 산화물전극은 열변형에 대해 매우 안정하여 열처리 후, 비저항이나 표면 형상의 변화가 적으며, 얇은 두께에서도 균일하게 박막이 형성되어 그 특성이 다층금속전극에 비해 매우 뛰어남을 확인하였다.

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A brief review on the effect of impurities on the atomic layer deposited fluorite-structure ferroelectrics (원자층증착법으로 증착된 강유전성 플루오라이트 구조 강유전체 박막의 불순물 효과)

  • Lee, Dong Hyun;Yang, Kun;Park, Ju Yong;Park, Min Hyuk
    • Journal of Surface Science and Engineering
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    • v.53 no.4
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    • pp.169-181
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    • 2020
  • The ferroelectricity in emerging fluorite-structure oxides such as HfO2 and ZrO2 has attracted increasing interest since 2011. Different from conventional ferroelectrics, the fluorite-structure ferroelectrics could be reliably scaled down below 10 nm thickness with established atomic layer deposition technique. However, defects such as carbon, hydrogen, and nitrogen atoms in fluorite-structure ferroelectrics are reported to strongly affect the nanoscale polymorphism and resulting ferroelectricity. The characteristic nanoscale polymorphism and resulting ferroelectricity in fluorite-structure oxides have been reported to be influenced by defect concentration. Moreover, the conduction of charge carriers through fluorite-structure ferroelectrics is affected by impurities. In this review, the origin and effects of various kinds of defects are reviewed based on existing literature.

Efficiency Improvement of Metal-Mesh Electrode Type Photoelectrochemical Cells by Oxides Layer Coatings (산화물박막 증착에 의한 금속 메쉬전극 구조 광전기화학셀의 효율 개선에 관한 연구)

  • Han, Chi-Hwan;Park, Seon-Hee;Sung, Youl-Moon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.3
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    • pp.584-587
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    • 2011
  • In this work, the $TiO_2$ and $SnO_2$ thin films as blocking layers were coated directly onto the metal-mesh electrode surface to prevent unnecessary inflow of back-transfer electrons from the electrolyte ($I^-/I_3^-$) to the metal-mesh electrode. The DSCs were fabricated with working electrode of SUS mesh coated with blocking $TiO_2$ and $SnO_2$ layers, dye-attached mesoporous $TiO_2$ film, gel electrolyte and counter electrode of Pt-deposited F:$SnO_2$. From the experimental result, it was ascertained that the efficiency of metal electrode coated with $TiO_2$ by Dip-coating was superior to that of metal electrode coated with $SnO_2$ by Dip-coating and screen printing with the results of experiments. The photo-current conversion efficiency of the cell obtained from optimum fabrication condition was 3% ($V_{oc}$=0.61V, $J_{sc}$=11.64 mA/$cm^2$, ff=0.64) under AM1.5, 100 mW/$cm^2$ illumination.

Study on YBCO coated conductor characteristics dependent on deposition method of $CeO_2$ capping layer ($CeO_2$ capping layer의 증착 방법에 따른 YBCO coated conductor 특성 연구)

  • Yang, Joo-Saeng;Ko, Rock-Kil;Kim, Ho-Sup;Ha, Hong-Soo;Park, Yu-Mi;Song, Kyu-Jeong;Oh, Sang-Soo;Park, Chan;Jo, Wiliiam
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.268-269
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    • 2005
  • YBCO 박막형 초전도체(coated conductor) 제조를 위해서는 여러 층의 완충층이 필요하다. 현재 일반적인 완충층의 구조는 seed layer로써 $Y_2O_3$, diffusion barrier로 YSZ, capping layer로 $CeO_2$가 사용되고 있다. 특히, capping layer로 $CeO_2$는 YBCO와 lattice mismatch가 매우 우수한 산화물로 이용되고 있다 본 연구에서는 $CeO_2$ capping layer가 증착 방법에 따라 그 위에 증착되어지는 초전도층의 특성에 어떤 영향을 미치는지 연구하였다. $CeO_2$를 thermal evaporation과 PLD (pulsed laser deposition) 증착 방법으로 증착 한 후 그 위에 PLD 방법으로 YBCO를 증착하여 coated conductor의 성능을 평가하였다.

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Fabrication and Electrochemical Characterization of All Solid State Rechargeable Li-Mn Oxide Batteries (리튬-망간 산화물을 이용한 전고상 이차 전지의 제작 및 전기화학적 특성)

  • Park, Young-Sin;Sin, Jin-Wook;Lee, Byung-Il;Joo, Seung-Ki
    • Korean Journal of Materials Research
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    • v.8 no.4
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    • pp.323-327
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    • 1998
  • All solid state lithium based rechargeable batteries were fabricated in a cell structure of Li/PEO-$LiCIO_4$-PC /$LIMn_2O_4$$LIMn_2O_4$ thin films were prepared by RF magnetron sputtering and the spinel structure could be obtained by Rapid Thermal Annealing (RT A) process at the temperature of around 750$750^{\circ}C$ . Room temperature cycling of this cell showed a nearly constant cell potential of 4 V( us. Li) and good reversibility.

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Mechanical Property Evaluation of Dielectric Thin Films for Flexible Displays using Organic Nano-Support-Layer (유기 나노 보강층을 활용한 유연 디스플레이용 절연막의 기계적 물성 평가)

  • Oh, Seung Jin;Ma, Boo Soo;Yang, Chanhee;Song, Myoung;Kim, Taek-Soo
    • Journal of the Microelectronics and Packaging Society
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    • v.28 no.3
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    • pp.33-38
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    • 2021
  • Recently, rollable and foldable displays are attracting great attention in the flexible display market due to their excellent form factor. To predict and prevent the mechanical failure of the display panels, it is essential to accurately understand the mechanical properties of brittle SiNx thin films, which have been used as an insulating film in flexible displays. In this study, tensile properties of the ~130 nm- and ~320 nm-thick SiNx thin films were successfully measured by coating a ~190 nm-thick organic nano-support-layer (PMMA, PS, P3HT) on the fragile SiNx thin films and stretching the films as a bilayer state. Young's modulus values of the ~130 nm and ~320 nm SiNx thin films fabricated through the controlled chamber pressure and deposition power (A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W) were calculated as A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa and A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa, respectively. As a result, Young's modulus of ~320 nm SiNx thin films fabricated through the same deposition condition increased compared to the ~130 nm SiNx thin films. The tensile testing method using the organic nano-support-layer was effective in the precise measurement of the mechanical properties of the brittle thin films. The method developed in this study can contribute to the robust design of the rollable and foldable displays by enabling quantitative measurement of mechanical properties of fragile thin films for flexible displays.

Optimization of ZnO-based transparent conducting oxides for thin-film solar cells based on the correlations of structural, electrical, and optical properties (ZnO 박막의 구조적, 전기적, 광학적 특성간의 상관관계를 고려한 박막태양전지용 투명전극 최적화 연구)

  • Oh, Joon-Ho;Kim, Kyoung-Kook;Song, Jun-Hyuk;Seong, Tae-Yeon
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.11a
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    • pp.42.2-42.2
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    • 2010
  • Transparent conducting oxides (TCOs) are of significant importance for their applications in various devices, such as light-emitting diodes, thin-film solar cells, organic light-emitting diodes, liquid crystal displays, and so on. In order for TCOs to contribute to the performance improvement of these devices, TCOs should have high transmittance and good electrical properties simultaneously. Sn-doped $In_2O_3$ (ITO) is the most commonly used TCO. However, indium is toxic and scarce in nature. Thus, ZnO has attracted a lot of attention because of the possibility for replacing ITO. In particular, group III impurity-doped ZnO showed the optoelectronic properties comparable to those of ITO electrodes. Al-doped ZnO exhibited the best performance among various doped ZnO films because of the high substitutional doping efficiency. However, in order for the Al-doped ZnO to replace ITO in electronic devices, their electrical and optical properties should further significantly be improved. In this connection, different ways such as a variation of deposition conditions, different deposition techniques, and post-deposition annealing processes have been investigated so far. Among the deposition methods, RF magnetron sputtering has been extensively used because of the easiness in controlling deposition parameters and its fast deposition rate. In addition, when combined with post-deposition annealing in a reducing ambient, the optoelectronic properties of Al-doped ZnO films were found to be further improved. In this presentation, we deposited Al-doped ZnO (ZnO:$Al_2O_3$ = 98:2 wt%) thin films on the glass and sapphire substrates using RF magnetron sputtering as a function of substrate temperature. In addition, the ZnO samples were annealed in different conditions, e.g., rapid thermal annealing (RTA) at $900^{\circ}C$ in $N_2$ ambient for 1 min, tube-furnace annealing at $500^{\circ}C$ in $N_2:H_2$=9:1 gas flow for 1 hour, or RTA combined with tube-furnace annealing. It is found that the mobilities and carrier concentrations of the samples are dependent on growth temperature followed by one of three subsequent post-deposition annealing conditions.

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Magnetic Properties of Cr-Doped Inverse Spinel Fe3O4 Thin Films (Cr 치환된 역스피넬 Fe3O4 박막의 자기적 특성)

  • Lee, Hee-Jung;Choi, Seung-Li;Lee, Jung-Han;Kim, Kwang-Joo;Choi, Dong-Hyeok;Kim, Chul-Sung
    • Journal of the Korean Magnetics Society
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    • v.17 no.2
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    • pp.51-54
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    • 2007
  • By substituting Cr in inverse-spinel $Fe_3O_4,\;Cr_xFe_{3-x}O_4$ thin film samples were prepared by sol-gel spin-coating method and their structural electronic, and magnetic properties were analyzed. X-ray diffraction indicates that the lattice constant decrease with increasing Cr composition (x). This result can be explained in terms of occupation of octahedral sites by $Cr^{3+}$ ions with smaller ionic radius than that of $Fe^{3+}$ Vibrating sample magnetometry measurements on the samples at room temperature revealed that saturation magnetization ($M_s$) decrease by Cr substitution, explainable by comparing spin magnetic moment among the related transition-metal ions. A decrease of magnetoresistence effect with x was observed, similar to that of $M_s$. The coercivity of the $Cr_xFe_{3-x}O_4$ films was found to increase with x, attributed to the increase of magnetic anisotropy by the existence of octahedral $Cr^{3+}(d^3)$.