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KCI등재

압전재료의 기초 물성 측정

Practical Guide to the Characterization of Piezoelectric Properties

강우석 ( Woo-seok Kang ) , 이건주 ( Geon-ju Lee ) , 조욱 ( Wook Jo )
  • : 한국전기전자재료학회
  • : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권5호
  • : 연속간행물
  • : 2021년 09월
  • : 301-313(13pages)
전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.)

DOI


목차

1. 서 문
2. 각 특성별 측정 방법
감사의 글
REFERENCES

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초록 보기

본 논문은 대학 연구실과 산업현장에서 강유전 압전 분야 연구를 갓 시작한 이들이 압전 소재의 특성에 대한 기초적, 이론적 개념에 대해서는 각종 교과서와 논문을 통해 쉽게 접할 수 있는 반면, 그 특성들이 실제로 어떻게 측정되고 평가되는 지에 대한 정보를 얻기가 힘들다는 점에 착안하여 압전 분야 입문자가 관련 측정 기술을 보다 쉽게 이해하고 접근할 수 있도록 돕는 것을 목적으로 한다. 기초 유전 물성인 임피던스에 기반한 유전상수와 유전손실 측정법을 시작으로 압전상수, 전기기계결합계수, 품질계수 및 측정 방법에 대해 논의하고, 강유전성을 대표하는 전계에 따른 분극 변화 측정법에 대해 기술하였다. 본 논문에서는 이미 표준화되어 있는 측정법들을 소개하고 있지만, 이를 숙지하고 응용한다면 보다 도전적이고 창의적인 측정법을 도출할 수 있을 것으로 기대한다.
Theoretical background for the meaning of various piezoelectric properties can be easily found in a number of textbooks and academic papers. In contrast, how they are actually measured and characterized are rarely described, though this information would be the most important especially to the researchers who just started working on the field. It follows that this report was intended to provide a practical guidance for measuring basic but essential properties of ferroelectric-based piezoelectric materials. The discussion begins with how to measurement dielectric properties such as dielectric permittivity and loss (dissipation factor), followed by piezoelectric properties such as piezoelectric constants, electromechanical coupling factor, and quality factor as well as ferroelectric features, i.e., electric field dependent polarization hysteresis. Though our discussion here is limited to the techniques that are already well-standardized, it is expected to make a seed to be developed into more challenging and creative ones.

UCI(KEPA)

간행물정보

  • : 공학분야  > 전기공학
  • : KCI등재
  • :
  • : 격월
  • : 1226-7945
  • : 2288-3258
  • : 학술지
  • : 연속간행물
  • : 1988-2021
  • : 4586


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34권6호(2021년 11월) 수록논문
최근 권호 논문
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1제일원리 계산을 활용한 전기화학 촉매 연구

저자 : 김동연 ( Dong Yeon Kim )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 393-400 (8 pages)

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As the recent climate problems are getting worse year after year, the demands for clean energy materials have highly increased in modern society. However, the candidate material classes for clean energy expand rapidly and the outcomes are too complex to be interpreted at laboratory scale (e.g., multicomponent materials). In order to overcome these issues, the firstprinciples calculations are becoming attractive in the field of material science. The calculations can be performed rapidly using virtual environments without physical limitations in a vast candidate pool, and theory can address the origin of activity through the calculations of electronic structure of materials, even if the structure of material is too complex. Therefore, in terms of the latest trends, we report academic progress related to the first-principles calculations for design of efficient electrocatalysts. The basic background for theory and specific research examples are reported together with the perspective on the design of novel materials using first-principles calculations.

KCI등재

2자성 액추에이터 기반의 소프트 로봇

저자 : 노규령 ( Gyu-Lyeong Nor ) , 최문기 ( Moon Kee Choi )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 401-415 (15 pages)

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Soft robots are promising devices for applications in drug delivery, sensing, and manufacturing. Traditional hard robotics are manufactured with rigid materials and their degrees of motion are constrained by the orientation of the joints. In contrast to rigid counterpart, soft robotics, employing soft and stretchable materials that easily deforms in shape, can realize complex motions (i.e., locomotion, swimming, and grappling) with a simple structure, and easily adapt to dynamic environment. Among them, the magnetic actuators exhibit unique characteristics such as rapid and accurate motion control, biocompatibility, and facile remote controllability, which make them promising candidates for the next-generation soft robots. Especially, the magnetic actuators instantly response to the stimuli, and show no-hysteresis during the recovery process, essential for continuous motion control. Here, we present the state-of-the-art fabrication process of magnetically controllable nano-/micro-composites, magnetically aligning process of the composites, and 1-dimensional/multi-dimensional multimodal motion control for the next-generation soft actuators.

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3COMSOL Multiphysics를 활용한 캔틸레버 형태의 압전 에너지 하베스터 구조 해석 시뮬레이션

저자 : 곽민섭 ( Min Sub Kwak ) , 황건태 ( Geon-tae Hwang )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 416-425 (10 pages)

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In the 4th industrial age, electronic devices are becoming smaller and lighter with a low power consumption to overcome spatial limitation. The piezoelectric energy harvesters can convert mechanical kinetic energy into electric energy; thus, enabling the operation of small electronic devices. Recently, various piezoelectric harvesters have been reported and the electric output from these harvesters could be anticipated by theoretical analysis methods. For example, COMSOL Multiphysics software provides a theoretical simulation of piezoelectric effect with a combination of mechanical and electrical phenomena in the piezoelectric materials. This article introduces a brief modeling of piezoelectric harvester to investigate mechanical stress and electrical output of harvesting devices by the COMSOL Multiphysics software.

KCI등재

4열경화성 에폭시를 이용한 가스 절연 개폐기용 절연 스페이서의 사출 성형 최적화 시뮬레이션

저자 : 배재성 ( Jaesung Bae ) , 이원창 ( Wonchang Lee ) , 지홍섭 ( Hongsub Jee ) , 홍병유 ( Byungyou Hong ) , 이재형 ( Jaehyeong Lee )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 426-432 (7 pages)

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Injection molding is used in many industrial fields such as home appliances, vehicle parts, and electronic device parts because various resins can be molded, leading to mass production of complex shapes. Generally, the empirical prediction method is used to set the initial processing conditions of injection molding. However, this approach requires a lot of cost and its presented solution is not accurate. In this paper, injection molding was simulated through the MoldflowTM in order to manufacture the spacer for gas insulated switch. Through the simulation, the flow of the resin with respect to the diameter of the inlet was analyzed. It was found that the process was possible at a higher resin temperature as the diameter of the inlet increased. In addition, through thermal analysis during injection of the resin, it was confirmed that a stagnation phenomenon occurred at the insert portion during injection molding, and the temperature of the resin was higher than that of the mold. As in this paper, if the spacer is manufactured by optimizing the injection hole and the temperature of the injection process based on simulation, it is expected that the spacer can be manufactured with high productivity.

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5고출력 슁글드 모듈 제작을 위한 결정질 실리콘 태양전지 분할 셀의 전기적 특성

저자 : 노은빈 ( Eun Bin Noh ) , 배재성 ( Jae Sung Bae ) , 김정훈 ( Jung Hoon Kim ) , 유종현 ( Jong Hyun You ) , 이재형 ( Jaehyeong Lee )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 433-437 (5 pages)

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As the demand for new and renewable energy increases due to the depletion of fossil fuels, solar power generation, a core energy source for new and renewable energy, requires research on solar modules for high output power generation. In this paper, the electrical characteristics of solar cell strip at the edge and in the center of single-crystal silicon having a semi-square shape were analyzed. The cell strip located in the center showed the efficiency increase by 0.26% compared to the cell strip at the edge of the solar cell. A shingled photovoltaic module was manufactured for each cell strip. As a result, the output power of the module using the cell strip located in the center was higher by 0.992%.

KCI등재

6YBa2Cu3O7-y 초전도 벌크의 중성자 조사 효과

저자 : 이상헌 ( Sang Heon Lee )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 438-441 (4 pages)

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The electrical characteristics of single-crystal composite superconductors produced by a melting process were studied by neutron irradiation. In order to improve the current characteristics of the YBa2Cu3O7-y superconductor, it is necessary to form an effective flux pinning center inside the superconductor. In this study, an increase in flux pinning was attempted through neutron irradiation onto YBa2Cu3O7-y superconductors. The neutron irradiation was performed at 30 MeV for 500 sec, The electrical properties of the superconductors were measured in a magnetic field of 5 Tesla at 50 K using a magnetic properties measurement system (MPMS). After neutron irradiation, the critical current density of the YBa2Cu3O7-y superconductor in a 1 Tesla magnetic field was 1×105 A/㎠. Once neutrons were irradiated at 30 MeV and 10 μA for 500 sec, the critical current density was observed to increase significantly. When neutrons are irradiated to a superconductor, micro-defects are created in the superconductor, and they act as flux pinning centers that hold the magnetic field generated when an electric current flows.

KCI등재

7전기열량소자용 Ag 첨가량에 따른 K(Ta,Nb)O3 세라믹스의 구조적·전기적 특성

저자 : 이민성 ( Min-sung Lee ) , 박병준 ( Byeong-Jun Park ) , 임정은 ( Jeong-Eun Lim ) , 이삼행 ( Sam-haeng Lee ) , 이명규 ( Myung-gyu Lee ) , 박주석 ( Joo-Seok Park ) , 이성갑 ( Sung-gap Lee )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 442-448 (7 pages)

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In this work, the (K1-xAgx)(Ta0.8Nb0.2)O3 (x=0.1-0.4) ceramics were fabricated using mixed-oxide method, and their structural and electrical properties were measured. All specimens represented a pseudo cubic structure with the lattice constant of 0.3989 nm. When 0.4 mol of Ag was added, second phases induced from metallic Ag and K2(Ta,Nb)6O16 phase were observed. Dielectric constant and dielectric loss of K(Ta0.8Nb0.2)O3 specimen doped with 0.3 mol of Ag were 2,737 and 0.446, respectively. The curie temperature was about -5℃, which does not change with Ag addition. The remanent polarization began to decrease sharply around 12~15℃, and the temperature at which the remanent polarization began to decrease as the applied voltage increased shifted to the high temperature side. The electrocaloric effect (ΔT) and electrocaloric efficiency (ΔT/ΔE) of the (K0.7Ag0.3)(Ta0.8Nb0.2)O3 ceramics were 0.01024℃ and 0.01825 KmV-1, respectively.

KCI등재

8고출력 슁글드 태양광 모듈 제작을 위한 스트링 연결에 관한 연구

저자 : 김주휘 ( Juhwi Kim ) , 김정훈 ( Junghoon Kim ) , 정채환 ( Chaehwan Jeong ) , 최원용 ( Wonyoung Choi ) , 이재형 ( Jaehyeong Lee )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 449-453 (5 pages)

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Interest and investment in renewable energy have increased worldwide, highlighting the need for renewable energy. Solar energy was the most promising energy of all renewable energy sources, and it has the highest investment value. Because photovoltaics require a certain amount of area for installation, high density and high output performance are required. Shingled module is a promising technology in that they are featured by higher density and higher output compared to the conventional modules. Shingled technology uses a laser scribing to divide solar cells that are to be bonded with electrically conductive adhesive (ECA) to produce and connect strings, which has a higher output in the same area than the conventional modules. In the process of producing solar modules, metal ribbons are used to interconnect cells, but they are also needed for string connections in shingled solar cells. Accordingly, in this study, we researched the interconnection that best suits the connector that joins the string to the string. The module outputs produced under the conditions of the string interconnection were compared and analyzed.

KCI등재

9비카드뮴계 InZnP/ZnSe/ZnS 코어쉘 양자점의 발광 특성

저자 : 이영기 ( Young-ki Lee ) , 이민상 ( Min-Sang Lee ) , 이정미 ( Jeong-mi Lee ) , 원대희 ( Dae-Hee Won ) , 김종만 ( Jong-man Kim )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 454-460 (7 pages)

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In this work, we synthesized alloy-core InZnP quantum dots, which are more efficient than single-core InP quantum dots, using a solution process method. The effect of synthesis conditions of alloy core on optical properties was investigated. We also investigated the conditions that make up the gradient shell to minimize defects caused by lattice mismatch between the InZnP core and ZnS is 7.7%. The stable synthesis temperature of the InZnP alloy core was 200℃. Quantum dots consisting of three layered ZnSe gradient shell and single layered ZnS exhibited the best optical property. The properties of quantum dots synthesized in 100 ml and in 2,000 ml flasks were almost equal.

KCI등재

10열확산 프로세스에 의한 초전도 벌크 합성

저자 : 이상헌 ( Sang Heon Lee )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 6호 발행 연도 : 2021 페이지 : pp. 461-465 (5 pages)

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A diffusion heat treatment process for YBa2Cu3O7-y bulk superconductor in a Gd2O3 powder was attempted. As a result of measuring the critical temperature of the superconducting bulk, there was no change in the superconducting transition temperature as the Gd particles diffused into the YBa2Cu3O7-y lattice, resulting in dense microstructure. As a result of measuring the critical current, the critical current density (Jc) of the superconducting bulk having treated by the Gd thermal diffusion treatment at 0 T increased to 3×104 A/㎠ at 0 T, which was higher than that of the superconducting bulk without thermal diffusion treatment. The surface magnetic force of the superconducting bulk with Gd thermal diffusion treatment was observed at the center of the superconducting bulk with the maximum trapped magnetic force (Hmax) of 1.51 kG. This result means that the Gd thermal diffusion treatment contributes to improving the critical current density Jc of YBa2Cu3O7-y, and it is believed that Gd particles migrating into the superconducting bulk through thermal diffusion either fill the surface pores of YBa2Cu3O7-y superconductors or act as a flux pinning center.

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1국문논문지 개편과 관련하여

저자 : 조욱 ( Wook Jo )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 269-270 (2 pages)

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2자기-기계-전기 변환소자를 이용한 에너지 하베스팅 기술

저자 : 황건태 ( Geon-tae Hwang ) , 류정호 ( Jungho Ryu ) , 윤운하 ( Woon-ha Yoon )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 271-282 (12 pages)

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The internet of things (IoT) technology is a key component for the advent of 4th industrial revolution, which is the network of home appliances, infrastructures, and vehicles to remotely investigate these systems. For the operation of compact IoT devices, batteries are widely used as electric power, and the limited lifetime of batteries inevitably leads to periodic replacement. Magneto-mechano-electric (MME) generators may be alternatives to batteries inside the IoT devices by converting stray magnetic field into electric energy, since we are always surrounded by ambient alternating current (AC) magnetic fields induced from electric power transmission lines everywhere. This article reviews the recent domestic research progress in high-performance MME generators and their application field for IoT and electronic devices.

KCI등재

3할라이드 페로브스카이트 단결정

저자 : 최진산 ( Jin San Choi ) , 조재훈 ( Jae Hun Jo ) , 우도현 ( Do Hyun Woo ) , 황영훈 ( Young-hun Hwang ) , 김일원 ( Ill Won Kim ) , 김태헌 ( Tae Heon Kim ) , 안창원 ( Chang Won Ahn )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 283-295 (13 pages)

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For the last decades, a research hotspot for the halide perovskites (HPs) is now showing great progress in terms of improving efficiency for numerous photovoltaic devices (PVDs). However, it still faces challenges in the case of long-term stability in the air atmosphere. Defect-free high-quality HP single crystals show their promising properties for the remarkable development of highly efficient and stable PVDs. Here, we summarize the growth processing routes for the stable HP single crystals as well as briefly discuss the pros and cons of those well-established synthesis routes. Furthermore, we briefly include the comparison note between the HP single crystals and polycrystalline perovskite films regarding their device applications. Based on the future progress, the review concludes subjective perspectives and current challenges for the development of HPs high-quality PVDs.

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4FinFET 및 GAAFET의 게이트 접촉면적에 의한 열저항 특성과 Fin-Layout 구조 최적화

저자 : 조재웅 ( Jaewoong Cho ) , 김태용 ( Taeyong Kim ) , 최지원 ( Jiwon Choi ) , 최자양 ( Ziyang Cui ) , 신동욱 ( Dongxu Xin ) , 이준신 ( Junsin Yi )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 296-300 (5 pages)

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The performance of devices has been improved with fine processes from planar to three-dimensional transistors (e.g., FinFET, NWFET, and MBCFET). There are some problems such as a short channel effect or a self-heating effect occur due to the reduction of the gate-channel length by miniaturization. To solve these problems, we compare and analyze the electrical and thermal characteristics of FinFET and GAAFET devices that are currently used and expected to be further developed in the future. In addition, the optimal structure according to the Fin shape was investigated. GAAFET is a suitable device for use in a smaller scale process than the currently used, because it shows superior electrical and thermal resistance characteristics compared to FinFET. Since there are pros and cons in process difficulty and device characteristics depending on the channel formation structure of GAAFET, we expect a mass-production of fine processes over 5 nm through structural optimization is feasible.

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5압전재료의 기초 물성 측정

저자 : 강우석 ( Woo-seok Kang ) , 이건주 ( Geon-ju Lee ) , 조욱 ( Wook Jo )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 301-313 (13 pages)

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본 논문은 대학 연구실과 산업현장에서 강유전 압전 분야 연구를 갓 시작한 이들이 압전 소재의 특성에 대한 기초적, 이론적 개념에 대해서는 각종 교과서와 논문을 통해 쉽게 접할 수 있는 반면, 그 특성들이 실제로 어떻게 측정되고 평가되는 지에 대한 정보를 얻기가 힘들다는 점에 착안하여 압전 분야 입문자가 관련 측정 기술을 보다 쉽게 이해하고 접근할 수 있도록 돕는 것을 목적으로 한다. 기초 유전 물성인 임피던스에 기반한 유전상수와 유전손실 측정법을 시작으로 압전상수, 전기기계결합계수, 품질계수 및 측정 방법에 대해 논의하고, 강유전성을 대표하는 전계에 따른 분극 변화 측정법에 대해 기술하였다. 본 논문에서는 이미 표준화되어 있는 측정법들을 소개하고 있지만, 이를 숙지하고 응용한다면 보다 도전적이고 창의적인 측정법을 도출할 수 있을 것으로 기대한다.

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6에어로졸 증착한 세라믹/금속 복합막의 금속 함량에 따른 습도 감지 특성 연구

저자 : 김익수 ( Ik-soo Kim ) , 구상모 ( Sang-mo Koo ) , 박철환 ( Chulhwan Park ) , 신원호 ( Weon Ho Shin ) , 이동원 ( Dong-won Lee ) , 오종민 ( Jong-min Oh )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 314-320 (7 pages)

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Controlling ambient humid condition through high performance humidity sensors has become important for various fields, including industrial process, food storage, and the preservation of historic remains. Although aerosol deposited humidity sensors using ceramic BaTiO3 (BT) material have been widely studied because of their longtime stability, there remain critical disadvantages, such as low sensitivity, low linearity, and slow response/recovery time in case of the sensors fabricated at room temperature. To achieve superior humidity sensing properties even at room temperature condition, BT-Cu composite films utilizing aerosol deposition (AD) process have been proposed based on the percolation theory. The BT-Cu composite films showed gradually improved sensing properties until the Cu concentration reached 15 wt% in the composite film. However, the excessive Cu (above 30 wt%) containing BT-Cu composite films showed a rapid decrease of the sensing properties. The results of observed surface morphology of the AD fabricated composite films, to figure out the metal filler effect, showed correlation between surface topography as well as size and the amount of open pores according to the metal filler content. Overall, it is very important not only dielectric constant of the humidity sensing films but also microstructures, because they affect either the variation range of capacitance by ambient humidity or adsorption/desorption of ambient humidity onto/from the humidity sensing films.

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7브러쉬 코팅 공정을 이용한 용액 기반 BiAlO 박막의 제작과 액정 소자에의 응용

저자 : 이주환 ( Ju Hwan Lee ) , 김대현 ( Dai-hyun Kim )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 321-326 (6 pages)

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We fabricated BiAlO thin film by a solution process with a brush coating to be used as liquid crystal (LC) alignment layer. Solution-processed BiAlO was coated on the glass substrate by brush process. Prepared thin films were annealed at different temperatures of 80℃, 180℃, and 280℃. To verify whether the BiAlO film was formed properly, X-ray photoelectron spectroscopy analysis was performed on Bi and Al. Using a crystal rotation method by polarized optical microscopy, LC alignment state was evaluated. At the annealing temperature of 280℃, the uniform homogenous LC alignment was achieved. To reveal the mechanism of LC alignment by brush coating, field emission scanning electron microscope was used. Through this analysis, spin-coated and brush coated film surface were compared. It was revealed that physical anisotropy was induced by brush coating at a high annealing temperature. Particles were aligned in one direction along which brush coating was made, resulting in a physical anisotropy that affects a uniform LC alignment. Therefore, it was confirmed that brush coating combined with BiAlO thin film annealed at high temperature has a significant potential for LC alignment.

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8리튬이온 배터리의 분리막 손상 요인별 방전펄스의 검출과 분석

저자 : 임승현 ( Seung-hyun Lim ) , 이경렬 ( Gyeong-yeol Lee ) , 김남훈 ( Nam-hoon Kim ) , 김동언 ( Dong-eon Kim ) , 길경석 ( Gyung-suk Kil )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 327-332 (6 pages)

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Lithium-ion batteries (LIBs) have become a main energy storage device in various applications, such as portable appliances, renewable energy facilities, and electric vehicles. However, the poor thermal stability of LIBs may cause explosion or fire. The thermal runaway is the result of a failure of the separator inside LIB. Damages like tearing, piercing, and collapsing of the separator were simulated in a mechanical, an electrical, and a thermal way, and small discharge pulses of a few mV were detected at the time of separator damages. From the experimental results, this paper provided a method that can identify the separator failure before thermal runaway in the aspect of a potential explosion and fire prevention measures.

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9벌크형 고온 초전도 합성

저자 : 이상헌 ( Sang Heon Lee )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 333-336 (4 pages)

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Oxide YBCO bulk superconductors are manufactured using the melt process. Because seed crystal growth method utilizes a slow-spreading layer-by-layer reaction, a long-term heat treatment is required to manufacture a single-crystal specimen of several cm. In this study, the melt process method was applied to compensate for the shortcomings of the seed crystal growth method. The thickness of the upper and lower pellets of the YBCO bulk was molded to 40 mm, and YBCO superconductor was produced by heat treatment. The measurement results of capture magnetism was in line with the literature. This results in a relationship that the higher the growth of Y211 particle in the YBCO, the higher the superconducting properties. We analyzed the YBCO superconductor, focusing on the Y2BaCuO5 particle distribution.

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10Phase Evolution, Thermal Expansion, and Microwave Dielectric Properties of Cordierite-Al2O3 Composite

저자 : Shin Kim , Eun-doe Song , Hae-jin Hwang , Joo-sung Lee , Sang-ok Yoon

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 34권 5호 발행 연도 : 2021 페이지 : pp. 337-341 (5 pages)

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Phase evolution, thermal and microwave dielectric properties of cordierite-Al2O3 composite were investigated. As the content of Al2O3 increased, mullite, sapphirine, and spinel were formed as secondary phases, implying that cordierite may be decomposed by the reaction with Al2O3. All sintered specimens exhibited dense microstructures. The densification occurred through liquid phase sintering. As the content of Al2O3 increased, the thermal expansion coefficient and the dielectric constant increased, whereas the quality factor decreased. The thermal expansion coefficient, the dielectric constant, and the quality factor of the 90 wt% cordierite 10 wt% Al2O3 composite sintered at 1,425℃ were 2.9×10-6 K-1, 5.1, and 34,844 GHz, respectively.

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