• 마이크로전자및패키징학회지
• /
• 제9권1호
• /
• pp.9-13
• /
• 2002

최근, 효율적인 다층박막 구조로된 풀칼라 유기 전계발광소자 (organic electroluminescient device, OELD)의 시제품이 개발된바 있다. 본 연구에서는 ITO (indium tin oxide)/glass 투명기판위에 다층구조의 OELD 소자를 진공 열증착법으로 제작하였다. 사용된 저분자 유기화합물은 전자수송 및 주입층으로 $Alq_3$(trim-(8-hydroxyquinoline)aluminum)와 CTM (carrier transfer material) 물질을 사용하였고, 정공수송 덴 주입층으로는 TPD (triphenyl-diamine)와 CuPc (copper phthalocyanine)를 각각 증착하였다. 발광휘도는 임계전압 10 V 이상에서 급격히 증가하였으며, $A1/CTM/Alq_3$/TPD/1TO 구조로된 OELDs 소자의 경우- l7 V전압에서 430 cd/$m^2$의 휘도특성과 파장 512 nm의 녹색 발광을 나타내었다. 한편 $Li-A1/Alq_3$/TPD/CuPC/1TO 다층구조로된 소자의 발광파장은 508 nm 이며, 발광휘도는 17 V에서 650 cd/$m^2$의 값을 얻을 수 있었다. Li-Al 전극을 갖는 다층구조에서 발광휘도의 증가는 정공주입층인 CuPc의 적층으로 발광층에서 재결합 효율이 개선되었기 때문이며, 또한 Li-Al 전극의 경우 Al전극에 비해 낮은 일함수(work function)를 갖기 때문으로 판단된다.

• Smart Structures and Systems
• /
• 제16권5호
• /
• pp.759-780
• /
• 2015

Based on the theory of piezoelasticity, the static performance of a piezoelectric bilayer cantilever fully covered with electrodes on the upper and lower surfaces is studied. Three models are considered, i.e., the sensor model, the driving displacement model and the blocking force model. By establishing suitable boundary conditions and proposing an appropriate Airy stress function, the exact solutions for piezoelectric bilayer cantilevers are obtained, and the effect of ambient thermal excitation is taken into account. Since the layer thicknesses and material parameters are distinguished in different layers, this paper gives unified solutions for composite piezoelectric bilayer cantilevers including piezoelectric bimorph and piezoelectric heterogeneous bimorph, etc. For some special cases, the simplifications of the present results are compared with other solutions given by other researches based on one-dimensional constitutive equations, and some amendments have been found. The present investigation shows: (1) for a PZT-4 piezoelectric bimorph, the amendments of tip deflections induced by an end shear force, an end moment or an external voltage are about 19.59%, 23.72% and 7.21%, respectively; (2) for a PZT-4-Al piezoelectric heterogeneous bimorph with constant layer thicknesses, the amendments of tip deflections induced by an end shear force, an end moment or an external voltage are 9.85%, 11.78% and 4.07%, respectively, and the amendments of the electrode charges induced by an end shear force or an end moment are both 1.04%; (3) for a PZT-4-Al piezoelectric heterogeneous bimorph with different layer thicknesses, the maximum amendment of tip deflection approaches 23.72%, and the maximum amendment of electrode charge approaches 31.09%. The present solutions can be used to optimize bilayer devices, and the Airy stress function can be used to study other piezoelectric cantilevers including multi-layered piezoelectric cantilevers under corresponding loads.

• 한국자동차공학회논문집
• /
• 제15권2호
• /
• pp.101-108
• /
• 2007

This paper presents an efficient meshless method for analyzing cracked piezoelectric structures subjected to mechanical and electrical loading. The method employs an element free Galerkin (EFG) formulation and an enriched basic function as well as special shape functions that contain discontinuous derivatives. Based on the moving least squares (MLS) interpolation approach, The EFG method is one of the promising methods for dealing with problems involving progressive crack growth. Since the method is meshless and no element connectivity data are needed, the burdensome remeshing procedure required in the conventional finite element method (FEM) is avoided. The numerical results show that the proposed method yields an accurate near-tip stress field in an infinite piezoelectric plate containing an interior hole. Another example is to study a ceramic multilayer actuator. The proposed model was found to be accurate in the simulation of stress and electric field concentrations due to the abrupt end of an internal electrode.

• Food Science and Biotechnology
• /
• 제14권4호
• /
• pp.554-557
• /
• 2005

As a device for taste sensation, an 8-channel taste evaluation system was prepared and applied for discriminant analysis of marketed liquor. The biomimetic polymer membranes for the system were prepared through a casting procedure by employing polyvinyl chloride, bis (2-ethylhexyl)sebacate as plasticizer and electroactive materials such as valinomycin in the ratio of 33:66:1, and were separately attached over the sensitive area of ion-selective electrodes to construct the corresponding taste sensor array. The sensor array in conjunction with a double junction reference electrode was connected to a high-input impedance amplifier and the amplified sensor signals were interfaced to a personal computer via an A/D converter. When the signal data from the sensor array for 3 groups of marketed liquor like Maesilju, Soju and beer were analyzed by principal component analysis after normalization, it was observed that the 1st, 2nd and 3rd principal component were responsible for most of the total data variance, and the analyzed liquor samples were discriminated well in 2 dimensional principal component planes composed of the 1st-2nd and the 1st-3rd principal component.

• 한국자동차공학회논문집
• /
• 제4권6호
• /
• pp.52-64
• /
• 1996

This paper presents an active position control of a single-rod cylinder system featuring an electrorheological(ER) fluid-based valve. The ER fluid consisting of silicone oil and chemically treated particles is firstly composed and its Bingham property is tested as a function of imposed electric field. A multi-channel plate type of ER valve is then designed and manufactured on the basis of the field-dependent Bingham model. Performance test of the ER valve is undertaken by evaluating pressure drop with respect to the number of electrode as well as the intensity of the electric field. Subsequently, the ER valve-cylinder system is constructed and its governing equation of motion is derived. A neural control scheme for position control of the cylinder is formulated by incorporating proportional-plus-derivative(PD) controller and implemented. Experimental results of both regulating and tracking control responses are presented in order to demonstrate the efficacy of the proposed ER valve-cylinder control system.

• E2M - 전기 전자와 첨단 소재
• /
• 제10권8호
• /
• pp.807-811
• /
• 1997

In this paper we have investigated the removal characteristics of NOx by pulsed corona discharge with a multi-pointplane electrode where a magnetic field is applied in the discharge region. The efficiency of NOx removal was measured and analyzed as a function of pulse frequency gas flow rate NOx initial concentration magnetic flux density. In this result the highest removal efficiency of NOx was obtained at the following operating conditions; the frequency =400[Hz] gas flow =1[$\ell$/min] initial concentration= 400[ppm] and magnetic flux density=0.36[T].

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 B
• /
• pp.1184-1186
• /
• 2004

Focus Electrode(FE) 기능을 갖는 진행파관 증폭기(TWTA)를 구동하기 위하여 고전압 펄스전원 장치가 필요하다. 이 전원장치는 영부터 -5.0 kV TWT 캐소드 고전압 위에서 펄스 출력으로 동작되어야 한다 고전압펄스전원장치는 바이어스 전압이 영부터 -1.5 kV사이를 연속적으로 가변 할 수 있어야 하고, 펄스의 반복 주파수는 CW로 부터 1 kHz 그리고 펄스폭은 $10\;{\mu}s$부터 $500\;{\mu}s$로 선택 가능하여야 한다. 그리고 출력펄스의 상승 및 하강 시간은 150 ns 보다 작아야 한다. 턴-온 및 오프의 스윗칭 시간을 만족시키기 위하여 고전압 스위치는 직렬로 연결된 FET 모듈을 사용하였다. 본 논문에서는 이러한 고전압 펄스전원장치의 설계 및 제작원리 그리고 시험결과에 대하여 다루었다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.139.2-139.2
• /
• 2013

6" Multi-crystal Silicon wafer has etched suing a remote - type RF Dielectric barrier discharge (RF DBD) at atmospheric pressure. DBD source is composed of Al electrode and coated Al2O3 dielectric as function of Ar/NF3 gas combination and input power used 13.56 MHz power supply. Ar gas flow rate is changed from 2 to 10 Slm, and NF3 flow rate is changed from 0.2~1 slm. At the result, NF3 flow rate Si etching rate also increase whit the increasing of NF3 flow rate But at 2 slm etching rate was decrease. In this experience, Max etching rate is 2.3 ${\mu}m/min$ when the scan time is 45 sec.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.1244-1245
• /
• 2008

Recently, piezoelectric transformer is applied to wide fields. Multi layer piezoelectric transformer has the advantage of high step up ratio, electromechanical coupling coefficient(Kp) and mechanical quality factor(Qm), but is indicated of peeling-phenomenon of electrode, rising sintering temperature made price of costly electrode. So in this study, it discuss on method for fabrication of rosen type piezoelectric transformers. For the fabrication as rosen type piezoelectric transformers, synthesized the powder using 0.01Pb$(ni_{1/3}Nb_{2/3})O_3$ - 0.08Pb$(Mn_{1/3}Nb_{2/3})O_3$ - 0.91Pb$(Zr_{0506}Ti_{0496})O_3$ (abbreviated as PNN-PMN-PZT) ceramics. The density, microstructure, dielectric and piezoelectric properties as a function of sintering temperature were investigated. The results indicated that the optimized properties of ceramics were obtained at sintering temperature of 1200$^{\circ}C$, showed the value of $d_{33}$=273pC/N, $K_p$=0.60 $Q_m$=1585, ${\varepsilon}_r$=1454, density=7.917$g/cm^3$ and $tan{\delta}$=0.0064.

• 한국공작기계학회논문집
• /
• 제16권2호
• /
• pp.100-105
• /
• 2007

Electro-rheological(ER) fluid and valve are fabricated and evaluated experimentally in its durability to utilize the hydraulic control systems for long term operation. The two-ports ER valve used in the experiment consist of twelve parallel multi-layer electrodes and provide a restriction to the passage of ER fluid because of the viscous pressure drop and a component induced by the electric field. The durability test of ER valve are performed by measuring the surface roughness of electrodes with variation of an electric field strength and test time(1000 or 1800min.). Also, the shear stress and shear rate are measured to evaluate the durability of ER fluid as function of time. After durability test, ER shear stress increases approximately proportional to the shear rate with applied electric field intensity, In the ER valve, the center line average height roughness(Ra) of copper electrode increases about 1.56 times and ten-point median height roughness(Rz) increases about 2.2 times after the durability test. An understanding of these durability is essential to predicting the service life of ER fluid and valves.