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빛의 밝기가 일정한 교류 구동 LED 조명기술

Alternating Current (AC) Powered LED Lighting Technology with Constant Brightness

이동원 ( Dong Won Lee ) , 안호명 ( Ho-myoung Ahn ) , 김병철 ( Byungcheul Kim )
  • : 한국전기전자재료학회
  • : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권5호
  • : 연속간행물
  • : 2022년 09월
  • : 466-470(5pages)
전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.)

DOI


목차

1. 서 론
2. 실험방법
3. 결과 및 고찰
4. 결 론
REFERENCES

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초록 보기

In order to widely disseminate LED lighting, LED lighting technology that directly uses AC commercial power has been recently introduced. AC powered LED lighting technology has a problem in that the light brightness of the LED changes because the voltage applied to the LED and the current flowing through the LED continuously change. In this study, when the LED current is greater than the design current, the current control signal generated by the controller is supplied to the current source to supply only the design current to the LED by increasing the voltage drop at the current source. If it is smaller than the design current, the controller is adjusted so that the current is supplied only to the LED without a voltage drop in the current source. It can be seen that the higher the maximum rectified voltage, the faster the lighting time of the LED light emitting block is, so that the power factor of the LED lighting is improved. The LED lighting technology proposed in this study enables LED lighting with constant light brightness, reduced power consumption, and long lifetime.

UCI(KEPA)

간행물정보

  • : 공학분야  > 전기공학
  • : KCI등재
  • :
  • : 격월
  • : 1226-7945
  • : 2288-3258
  • : 학술지
  • : 연속간행물
  • : 1988-2022
  • : 4676


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35권6호(2022년 11월) 수록논문
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1강유전체 고분자의 음의 압전 물성 및 상공존경계(MPB)에 대한 고찰

저자 : 임성빈 ( Sungbin Im ) , 부상돈 ( Sang Don Bu ) , 정창규 ( Chang Kyu Jeong )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 523-546 (24 pages)

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Morphotropic phase boundary (MPB), which is a special boundary that separates two or multiple different phases in the phase diagram of some ferroelectric ceramics, is an important concept in identifying physics that includes piezoelectric responses. MPB, which had not been discovered in organic materials until recently, was discovered in poly(vinylidene fluoride-co- trifluoroethylene (P(VDF-TrFE)), resulting from a molecular approach. The piezoelectric coefficient of P(VDF-TrFE) in this MPB region was achieved up to -63.5 pC N-1, which is about two times as large as the conventional value of -30 pC N-1 of P(VDF-TrFE). An order-disorder arrangement greatly affects the rise of the piezoelectric effect and the ferroelectric, paraelectric and relaxor ferroelectric of P(VDF-TrFE), so the arrangement and shape of the polymer chain is important. In this review, we investigate the origin of negative longitudinal piezoelectric coefficients of piezoelectric polymers, which is definitely opposite to those of common piezoelectric ceramics. In addition to the mainly discussed issue about MPB behaviors of ferroelectric polymers, we also introduce the consideration about polymer chirality resulting in relaxor ferroelectric properties. When the physics of ferroelectric polymers is unveiled, we can improve the piezoelectric and pyroelectric properties of ferroelectric polymers and contribute to the development of next-generation sensor, energy, transducer and actuator applications.

KCI등재

2나노물질 기반의 광변환층 개발 동향

저자 : 김동룡 ( Dongryong Kim ) , 최문기 ( Moon Kee Choi )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 547-555 (9 pages)

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Color conversion layer refers to a layer that converts the blue light emitted from the backlight into the red and green light. Heavy metal-free quantum dots and perovskite nanocrystals have attracted great attention as base materials for color conversion layers due to their outstanding optical characteristics. Here, we review recent advances in the development of color conversion layers based on quantum dots. First, we overview the representative optical characteristics of quantum dots and perovskite nanocrystals, and then introduce printing techniques for color converting layers including photolithography, inkjet printing, and nanoimprinting. Finally, we conclude this review with a brief perspective.

KCI등재

3Pymatgen 패키지를 이용한 구조 생성 및 제일원리계산에의 적용

저자 : 이대형 ( Dae-hyung Lee ) , 서동화 ( Dong-hwa Seo )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 556-561 (6 pages)

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밀도범함수이론(density functional theory, DFT)이 등장한 이래로, 이를 재료과학에 적용하여 에너지 재료 및 반도체와 같은 전자재료들의 연구개발에 활발하게 활용되고 있다. 하지만 DFT 계산 프로그램을 실행할 때 필요한 입력파일 생성 시 여러 가지 소재들에 대해 동일한 계산 조건을 맞춰 주고 파라미터들을 알맞게 설정해 줘야 올바른 계산결과 비교가 가능한데, 이런 부분들에 대해 진입 장벽이 높다는 어려움이 있다. 이에 본 논문에서는 Python Materials Genomics (pymatgen) 파이썬 패키지를 이용해 분자 및 결정구조를 다루고 널리 사용되는 DFT 계산 프로그램인 Vienna Ab initio Simulation Package (VASP) 및 Gaussian 입력 파일 생성에 대해 소개하고자 한다. 이를 통해 해당 프로그램에 대한 전문적인 지식이 많지 않더라도 보다 일관적인 계산 조건에서 결과들을 손쉽게 수행할 수 있게 되기를 기대한다.


Computational material science as an application of Density Functional Theory (DFT) to the discipline of material science has emerged and applied to the research and development of energy materials and electronic materials such as semiconductor. However, there are a few difficulties, such as generating input files for various types of materials in both the same calculating condition and appropriate parameters, which is essential in comparing results of DFT calculation in the right way. In this tutorial status report, we will introduce how to create crystal structures and to prepare input files automatically for the Vienna Ab initio Simulation Package (VASP) and Gaussian, the most popular DFT calculation programs. We anticipate this tutorial makes DFT calculation easier for the ones who are not experts on DFT programs.

KCI등재

4Self-Illuminated Smart Window Based on Polymer-Dispersed Liquid Crystal Mixed with Cu-doped ZnS

저자 : Eun Mi Kim , Gi-seok Heo

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 562-567 (6 pages)

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Novel self-illuminated smart windows were fabricated consisting of Cu-doped ZnS (ZnS:Cu) powder and polymer-dispersed liquid crystal (PDLC). This smart window shows not only switchable transparency but also self-illumination without any attachable luminous body. Its electro-optical characteristics, transmittance, and luminance were investigated in relation to various applied voltages and composition ratios. The optical transmittance and luminous intensity increased with increasing applied voltages. However, the optical transmittance decreased with increasing ZnS:Cu powder content. One of the self-illuminated smart windows, which was fabricated with 9 wt% of ZnS:Cu, achieved the optical transmittance of 60.5% (at 550 nm) and the luminance of 11.0 cd/m2 at 100 V. This smart window could be used as a normal switchable smart window in daytime and light-emitting signage at night.

KCI등재

5ESS의 전자 잡음 주파수 분석 및 제거

저자 : 안봉만 ( Bong Man Ahn ) , 한병성 ( Byoung Sung Han ) , 한운기 ( Un Ki Han ) , 이영관 ( Young Kwan Lee ) , 안현진 ( Hyun Jin An )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 568-575 (8 pages)

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This paper is a study on frequency analysis and electronic noise reduction of energy storage system (ESS). We acquired 4 necessary data for about 2 minutes and 4 seconds using a sampling frequency of 10,000 Hz in ESS. Fast Fourier transform (FFT) was used for electronic noise analysis from the acquired data. As a result, it was confirmed that DC component, fundamental wave, second and higher harmonic component exist. For the attenuation of harmonics, low-pass filter (LPF) was applied. We confirmed that an attenuation of approximately 59.3% appears from the second harmonic. The presence of many harmonic components in the data of the ESS was expected to occur due to the insufficiency of optimization among the modules inside the ESS. Therefore, we propose that a national certification system for ESS should be introduced to settle down the issue properly.

KCI등재

6진공 게이트 스페이서를 지니는 Bulk FinFET의 단채널효과 억제를 위한 소자구조 최적화 연구

저자 : 연지영 ( Ji-yeong Yeon ) , 이광선 ( Khwang-sun Lee ) , 윤성수 ( Sung-su Yoon ) , 연주원 ( Ju-won Yeon ) , 배학열 ( Hagyoul Bae ) , 박준영 ( Jun-young Park )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 576-580 (5 pages)

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Semiconductor devices have evolved from 2D planar FETs to 3D bulk FinFETs, with aggressive device scaling. Bulk FinFETs make it possible to suppress short-channel effects. In addition, the use of low-k dielectric materials as a vacuum gate spacer have been suggested to improve the AC characteristics of the bulk FinFET. However, although the vacuum gate spacer is effective, correlation between the vacuum gate spacer and the short-channel-effects have not yet been compared or discussed. Using a 3D TCAD simulator, this paper demonstrates how to optimize bulk FinFETs including a vacuum gate spacer and to suppress short-channel effects.

KCI등재

7광활성층 사용물질에 따라 변화하는 유기태양전지의 효율

저자 : 김유은 ( Yu-eun Kim ) , 김기환 ( Gi-hwan Kim )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 581-593 (13 pages)

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As energy depletion and environmental pollution problems are intensified, research has been conducted actively on alternative energy sources, an eco-friendly and continuous available energy conversion system. So has been organic solar cells whose efficiency is improved to 18.32%. The photoactive layer inside the solar cell is composed of a donor and a acceptor, and the combination of materials capable of effectively exchanging electrons greatly affects the efficiency of the organic solar cell. Accordingly, various researches have been conducted to improve the efficiency, and the maximum efficiency could be achieved by a solar cell with high carrier generation and low charge recombination characteristics through the introduction of a non-fullerene acceptor and material reconstruction. Organic solar cells are still difficult to commercialize due to their efficiency limitations and light stability, but if a photoactive layer consisting of a donor capable of efficiently absorbing long-wavelength light and an acceptor capable of forming an appropriate energy level is designed, the efficiency of the organic solar cell will reach 20%.

KCI등재

8몰드 변압기의 절연 진단을 위한 로고우스키형 부분방전 센서의 설계 및 제작

저자 : 이경렬 ( Gyeong-yeol Lee ) , 김성욱 ( Sung-wook Kim ) , 길경석 ( Gyung-suk Kil )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 594-602 (9 pages)

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Cast-resin transformers are widely installed in various electrical power systems because of their low operating cost and low influence on external environmental factors. However, when they have an internal defect during the manufacturing process or operation, a partial discharge (PD) occurs, and eventually destroys the insulation. In this paper, a Rogowski-type PD sensor was studied to replace commercial PD sensors used for the insulation diagnosis of power apparatus. The proposed PD sensor was manufactured with four different types of PCB-based winding structures, and it was analyzed in terms of the detection characteristics for standard calibration pulses and the changes of the output voltage according to the distance. The output increased linearly in accordance with the applied discharge amount. It was confirmed that the hexagon structure sensor had the highest sensitivity, because the winding cross-sectional area of the sensor was larger than others. In addition, as the distance from the defect increased, the output voltage of the sensors decreased by 7.32% on average. It was also confirmed that the attenuation rate according to the distance decreased as the input discharge amount increased. For the application of this new type sensor, PD electrode system was designed to simulate the void defect. Waveforms and PRPD patterns measured by the proposed PD sensors at DIV and 120% of DIV were the same as the results measured by MPD 600 based on IEC 60270. The proposed PD sensors can be installed on the inner wall of the transformer tank by coating its surfaces with a non-conductive material; therefore, it is possible to detect internal defects more effectively at a closer distance from the defect than the conventional sensors.

KCI등재

9이종접합 태양전지에서의 Bi-Layer 구조를 통한 향상된 개방전압특성에 대한 고찰

저자 : 김홍래 ( Hongrae Kim ) , 정성진 ( Sungjin Jeong ) , 조재웅 ( Jaewoong Cho ) , 김성헌 ( Sungheon Kim ) , 한승용 ( Seungyong Han ) , 수레쉬쿠마르듄겔 ( Suresh Kumar Dhungel ) , 이준신 ( Junsin Yi )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 603-609 (7 pages)

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Passivation quality is mainly governed by epitaxial growth of crystalline silicon wafer surface. Void-rich intrinsic a- Si:H interfacial layer could offer higher resistivity of the c-Si surface and hence a better device efficiency as well. To reduce the resistivity of the contact area, a modification of void-rich intrinsic layer of a-Si:H towards more ordered state with a higher density is adopted by adapting its thickness and reducing its series resistance significantly, but it slightly decreases passivation quality. Higher resistance is not dominated by asymmetric effects like different band offsets for electrons or holes. In this study, multilayer of intrinsic a-Si:H layers were used. The first one with a void-rich was a-Si:H(I1) and the next one a-SiOx:H(I2) were used, where a-SiOx:H(I2) had relatively larger band gap of ~2.07 eV than that of a-Si:H (I1). Using a-SiOx:H as I2 layer was expected to increase transparency, which could lead to an easy carrier transport. Also, higher implied voltage than the conventional structure was expected. This means that the a-SiOx:H could be a promising material for a high-quality passivation of c-Si. In addition, the i-a-SiOx:H microstructure can help the carrier transportation through tunneling and thermal emission.

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10잉크젯 프린팅 공정을 통해 제작된 BaTiO3 Capacitor의 유전특성 분석

저자 : 김유진 ( Yu-jin Kim ) , 이경영 ( Gyeong-yeong Lee ) , 이인곤 ( In-gon Lee ) , 홍익표 ( Ic-pyo Hong ) , 김지훈 ( Ji-hoon Kim )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 6호 발행 연도 : 2022 페이지 : pp. 610-615 (6 pages)

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BaTiO3 is one of the ferroelectric materials with excellent dielectric properties such as high dielectric constant, low dielectric loss, and is widely used for the manufacturing of capacitors, piezoelectric converters, microsensors, and ferroelectric memories. Inkjet printing is a technology which uses digital and contactless methods which significantly improves flexibility associated with material and structural design, reducing manufacturing costs. Therefore, the top and bottom electrodes, BaTiO3 ink, and photocurable resin were all printed by an inkjet to produce a BaTiO3 capacitor. The properties of the printed thin film were analyzed. It was confirmed that the photocurable resin ink was well-infiltrated between the BaTiO3 powder particles printed by inkjet. The dielectric properties of the capacitor such as dielectric constant which varies in accordance with frequency, polarization and tunability that changes with voltage, were measured.

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1결함제어를 통한 열전 반도체 연구 동향

저자 : 민유호 ( Yuho Min )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 419-430 (12 pages)

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Defects in solids play a vital role on thermoelectric properties through the direct impacts of electronic band structure and electron/phonon transports, which can improve the electronic and thermal properties of a given thermoelectric semiconductor. Defects in semiconductors can be divided into four different types depending on their geometric dimensions, and thus understanding the effects on thermoelectric properties of each type is of a vital importance. This paper reviews the recent advances in the various thermoelectric semiconductors through defect engineering focusing on the charge carrier and phonon behaviors. First, we clarify and summarize each type of defects in thermoelectric semiconductors. Then, we review the recent achievements in thermoelectric properties by applying defect engineering when introducing defects into semiconductor lattices. This paper ends with a brief discussion on the challenges and future directions of defect engineering in the thermoelectric field.

KCI등재

2강유전 세라믹의 전기장 인가에 따른 in situ X-선 회절 실험

저자 : 최진산 ( Jin San Choi ) , 김태헌 ( Tae Heon Kim ) , 안창원 ( Chang Won Ahn )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 431-438 (8 pages)

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기능성 소재연구에서 in situ 분석 기법은 외부 자극 (전기장, 자기장, 빛, 등) 또는 주변 환경 (온도, 습도, 압력, 등)과 같이 주어진 자극에 의해 소재의 물리적 특성이 어떻게 활성화/진화되는지 분석하는데 있어서 매우 중요하다. 특히, 전기장 인가에 따른 in situ X-선 회절(XRD) 실험은 다양한 강유전체, 압전체, 전왜 재료의 외부 전기장 인가에 따른 전기-기계적 반응의 기본 원리를 이해하기 위해 광범위하게 활용되었다. 본 튜토리얼 논문에서는 일반 실험실 규모의 XRD 장비를 이용하여 전기장 인가에 따른 in situ XRD 분석의 기본 원리/핵심 개념을 간략하게 소개한다. In situ XRD 측정법은 외부 전기장을 인가하여 구동되는 다양한 전기-기계 재료의 구조적 변형을 체계적으로 식별/모니터링하는 데 매우 유용할 것으로 기대한다.

KCI등재

3레이저 기반 플라즈모닉 어닐링을 통한 은 나노입자 자가 생성 및 소결 공정과 이를 활용한 메탈메쉬 전극 기반 투명 웨어러블 히터

저자 : 황윤식 ( Yun Sik Hwang ) , 남의연 ( Ui Yeon Nam ) , 김연욱 ( Yeon Uk Kim ) , 우유미 ( Yu Mi Woo ) , 허재찬 ( Jae Chan Heo ) , 박정환 ( Jung Hwan Park )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 439-444 (6 pages)

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Laser-induced plasmonic sintering of metal nanoparticles (NPs) is a promising technology to fabricate flexible conducting electrodes, since it provides instantaneous, simple, and scalable manufacturing strategies without requiring costly facilities and complex processes. However, the metal NPs are quite expensive because complicated synthesis procedures are needed to achieve long-term reliability with regard to chemical deterioration and NP aggregation. Herein, we report laser-induced Ag NP self-generation and sequential sintering process based on low-cost Ag organometallic material for demonstrating highquality microelectrodes. Upon the irradiation of laser with 532 nm wavelength, pre-baked Ag organometallic film coated on a transparent polyimide substrate was transformed into a high-performance Ag conductor (resistivity of 2.2 × 10-4 Ω·cm). To verify the practical usefulness of the technology, we successfully demonstrated a wearable transparent heater by using Ag-mesh transparent electrodes, which exhibited a high transmittance of 80% and low sheet resistance of 7 Ω/square.

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4PZT-PZN 세라믹의 미세구조가 압전 특성 및 TCC 거동에 미치는 영향

저자 : 서인태 ( Intae Seo ) , 최용수 ( Yongsu Choi ) , 조유리 ( Yuri Cho ) , 강형원 ( Hyung-won Kang ) , 김강산 ( Kang San Kim ) , 천채일 ( Chae Il Cheon ) , 한승호 ( Seung Ho Han )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 445-451 (7 pages)

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Ultrasonic sensor is suitable as a next-generation autonomous driving assist device because its lower price compared to that of other sensors and its sensing stability in the external environment. Although Pb(Zr, Ti)O3 (PZT)-relaxor ferroelectric system has excellent piezoelectric properties, the change in capacitance is large in the daily operating temperature range due to the low phase transition temperature. Recently, many studies have been conducted to improve the temperature stability of ferroelectric ceramics by controlling the grain size and crystal structure, so it is necessary to study the effect of the grain size on the piezoelectric properties and the temperature stability of PZT-relaxor ferroelectric system. In this study, the piezoelectric properties, phase transition temperature, and temperature coefficient of capacitance (TCC) of 0.9 Pb(Zr1-xTix)O3-0.1 Pb(Zn1/3Nb2/3)O3 (PZTx-PZN) ceramics with various grain sizes were investigated. PZTx-PZN ceramics with larger grain size showed higher piezoelectric properties and temperature stability, and are expected to be suitable for ultrasonic devices in the future.

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5플래시메모리소자의 구조에 대한 열적 데이터 삭제 효율성 비교

저자 : 김유정 ( You-jeong Kim ) , 이승은 ( Seung-eun Lee ) , 이광선 ( Khwang-sun Lee ) , 박준영 ( Jun-young Park )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 452-458 (7 pages)

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The electro-thermal erasing (ETE) configuration utilizes Joule heating intentionally generated at word-line (WL). The elevated temperature by heat physically removes stored electrons permanently within a very short time. Though the ETE configuration is a promising next generation NAND flash memory candidate, a consideration of power efficiency and erasing speed with respect to device structure and its scaling has not yet been demonstrated. In this context, based on 3-dimensional (3-D) thermal simulations, this paper discusses the impact of device structure and scaling on ETE efficiency. The results are used to produce guidelines for ETEs that will have lower power consumption and faster speed.

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6IoT를 사용한 센서 네트워크 기반의 실시간 토양 습도 모니터링

저자 : 김경헌 ( Kyeong Heon Kim ) , 김희동 ( Hee-dong Kim )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 459-465 (7 pages)

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This paper reports a method to use a wireless sensor network deployed in the field to real-time monitor soil moisture, warning when the moisture level reaches a specific value, and wirelessly controlling an additional device (LED or water supply system, etc.). In addition, we report all processes related to wireless irrigation system, including field deployment of sensors, real-time monitoring using a smartphone, data calibration, and control of additional devices deployed in the field by smartphone. A commercially available open-source Internet of Things (IoT) platform, NodeMCU, was used, which was combined with a 9V battery, LED and soil humidity sensor to be integrated into a portable prototype. The IoT-based soil humidity sensor prototype deployed in the field was installed next to a tree for on-site demonstration for the measurement of soil humidity in real-time for about 30 hours, and the measured data was successfully transmitted to a smartphone via Wifi. The measurement data were automatically transmitted via e-mail in the form of a text file, stored on the web, followed by analyses and calibrations. The user can check the humidity of the soil real-time through a personal smartphone. When the humidity of a soil reached a specific value, an additional device, an LED device, placed in the field was successfully controlled through the smartphone. This LED can be easily replaced by other electronic devices such as water supplies, which can also be controlled by smartphones. These results show that farmers can not only monitor the condition of the field real-time through a sensor monitoring system manufactured simply at a low cost but also control additional devices such as irrigation facilities from a distance, thereby reducing unnecessary energy consumption and helping improve agricultural productivity.

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7빛의 밝기가 일정한 교류 구동 LED 조명기술

저자 : 이동원 ( Dong Won Lee ) , 안호명 ( Ho-myoung Ahn ) , 김병철 ( Byungcheul Kim )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 466-470 (5 pages)

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In order to widely disseminate LED lighting, LED lighting technology that directly uses AC commercial power has been recently introduced. AC powered LED lighting technology has a problem in that the light brightness of the LED changes because the voltage applied to the LED and the current flowing through the LED continuously change. In this study, when the LED current is greater than the design current, the current control signal generated by the controller is supplied to the current source to supply only the design current to the LED by increasing the voltage drop at the current source. If it is smaller than the design current, the controller is adjusted so that the current is supplied only to the LED without a voltage drop in the current source. It can be seen that the higher the maximum rectified voltage, the faster the lighting time of the LED light emitting block is, so that the power factor of the LED lighting is improved. The LED lighting technology proposed in this study enables LED lighting with constant light brightness, reduced power consumption, and long lifetime.

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8매개변수 평가법을 이용한 압전재료의 재료물성 최적화 연구 Part I. 다결정 PZT 세라믹스

저자 : 신호용 ( Ho-yong Shin ) , 이호용 ( Ho-yong Lee ) , 홍일곡 ( Il-gok Hong ) , 김종호 ( Jong-ho Kim ) , 임종인 ( Jong-in Im )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 471-479 (9 pages)

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Recently, piezoelectric devices, such as ultrasonic surgery, ultrasonic atomizer, and ultrasonic speaker, are analyzed and designed by finite element simulation methods. However, the discrepancy between the design and the experiment results of the device typically occurs due to the inaccuracy of the piezoelectric material properties. To improve the simulation accuracy, the material properties of the PZT ceramics were better refined using parameter estimation method. The material parameters are elastic stiffness cEij and piezoelectric constant eij of PZT ceramics. The impedance curve characteristics for the LTE mode of PZT ceramics were calculated. The mismatch between the simulation and the experimental data were compared and minimized by a least square method. Finally, the simulated impedance data were compared with the experimental data for the various vibration modes of PZT ceramics and the optimized material properties of PZT ceramics were verified. To further verify the accuracy, this method was also applied to piezoelectric PMN-PT single crystals.

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9진공인터럽터의 내전압 성능 향상을 위한 전류컨디셔닝 기법 연구

저자 : 차영광 ( Young-kwang Cha ) , 이일회 ( Il-hoi Lee ) , 전기범 ( Ki-beom Jeon ) , 장지훈 ( Ji-hoon Jang ) , 주흥진 ( Heung-jin Ju )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 480-487 (8 pages)

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As a process to improve the insulation performance of VIs (Vacuum Interrupters), AC voltage conditioning is generally adopted by many manufacturers. Although the insulation performance is enhanced easily with AC Voltage conditioning, it has limitations when high recovery voltage is required due to high voltage rate or capacitive current switching. In particular, impurities such as oxides segregated on the electrode surface can be removed not by the energy level of the voltage conditioning but by the higher energy level achieved by the current conditioning process In this article, the current conditioning was carried out in various conditions and its validity was examined. The current conditioning was processed by changing the amplitude of applied current, arc time, the number of tests, and frequency. The insulation performance and the status of contact surface were checked as well. We concluded that as the applied charge quantity and the conditioning coverage area increase, the conditioning effect is much higher.

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10듀얼 마그네트론 스퍼터링 법으로 제조된 Pd-Doped Carbon 박막의 물리적 특성에서 Pd 타겟 전력의 영향에 대한 연구

저자 : 최영철 ( Young-chul Choi ) , 박용섭 ( Yong Seob Park )

발행기관 : 한국전기전자재료학회 간행물 : 전기전자재료학회논문지(J. Korean Inst. Electr. Electron. Mater. Eng.) 35권 5호 발행 연도 : 2022 페이지 : pp. 488-493 (6 pages)

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Generally, diamond-like carbon films (a-C:H, DLC) have been shown to have a low coefficient of friction, a high hardness and a low wear rate. Pd-doped C thin film was fabricated using a dual magnetron sputtering with two targets of graphite and palladium. Graphite target RF power was fixed and palladium target RF power was varied. The structural, physical, and surface properties of the deposited thin film were investigated, and the correlation among these properties was examined. The doping ratio of Pd increased as the RF power increased, and the surface roughness of the thin film decreased somewhat as the RF power increased. In addition, the hardness value of the thin film increased, and the adhesive strength was improved. It was confirmed that the value of the contact angle indicating the surface energy increases as the RF power increases. It was concluded that the increase in RF power contributed to the improvement of the physical properties of Pd-doped C thin film.

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