• Macromolecular Research
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• v.14 no.1
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• pp.38-44
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• 2006

Vacuum deposited copper phthalocyanine (CuPc) was placed as a thin interlayer between indium tin oxide (ITO) electrode and a hole transporting layer (HTL) in a multi-layered, organic, light-emitting diode (OLEOs). The well-stacked CuPc layer increased the stability and efficiency of the devices. Thermal annealing after CuPc deposition and magnetic field treatment during CuPc deposition were performed to obtain a stacked-CuPc layer; the former increased the stacking density of the CuPc molecules and the alignment of the CuPc film. Thermal annealing at about 100$^{circ}C$ increased the current flow through the CuPc layer by over 25$\%$. Surface roughness decreased from 4.12 to 3.65 nm and spikes were lowered at the film surface as well. However, magnetic field treatment during deposition was less effective than thermal treatment. Eventually, a higher luminescence at a given voltage was obtained when a thermally-annealed CuPc layer was placed in the present, multi-layered, ITO/CuPc/NPD/Alq3/LiF/AI devices. Thermal annealing at about 100$^{circ}C$ for 3 h produced the most efficient, multi-layered EL devices in the present study.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.335-338
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• 2008

New efficient red emitter having short p?-conjugation length and asymmetric bulky structure, 2-(7-diphenylamino-benzo[1,2,5]thiadiazole-4-ylmethylene)-malononitrile, was synthesized and characterized. Using this material as a dopant, we fabricated electroluminescence device with a structure of ITO/DNTPD/NPD/BTZA (5 wt% in Alq3)/Alq3/LiF/Al. The device exhibited a high brightness of 761 cd/m2 at a driving voltage of 4.8 V, and current efficiency is 0.75 cd/A. The Commission International de IEclairage (CIE) coordinates of the EL device were found to be (0.62, 0.37) at 10 mA/cm2.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.841-846
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• 2011

New green host materials, 9-phenyl-3-(4-(1-phenyl-1H-benzo[d] imidazol-2-yl)phenyl)-9H-carbazole (3a) and 9-(naphthyl-2-yl)-3-(4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl)-9H-carbazole (3b), have been designed and synthesized by attaching the electron transporting benzimidazole moiety to the hole transporting carbazole unit. These compounds have similar HOMO, LUMO levels and band-gap characteristics compared with CBP (4,4'-di(N-carbazolyl)biphenyl). The fabricated green phosphorescent OLED with this 3a host shows much better device performances compared to CBP-based one. The current and power efficiency is enhanced at least by 60 percent at a given constant luminance of 1000 cd/$m^2$.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.742-751
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• 2018

Electric vehicles (EV) are emerging as the future transportation vehicle reflecting their potential safe environmental advantages. Vehicle to Grid (V2G) system describes the hybrid system in which the EV can communicate with the utility grid and the energy flows with insignificant effect between the utility grid and the EV. The paper presents an optimal power control and energy management strategy for Plug-In Electric Vehicle (PEV) charging stations using Wind-PV-FC-Battery renewable energy sources. The energy management optimization is structured and solved using Multi-Objective Particle Swarm Optimization (MOPSO) to determine and distribute at each time step the charging power among all accessible vehicles. The Model-Based Predictive (MPC) control strategy is used to plan PEV charging energy to increase the utilization of the wind, the FC and solar energy, decrease power taken from the power grid, and fulfil the charging power requirement of all vehicles. Desired features for EV battery chargers such as the near unity power factor with negligible harmonics for the ac source, well-regulated charging current for the battery, maximum output power, high efficiency, and high reliability are fully confirmed by the proposed solution.

• Journal of Power Electronics
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• v.6 no.1
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• pp.18-28
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• 2006

The Electric Power Subsystem (EPS) is one of the most critical systems on any satellite because nearly every subsystem requires power. This makes the choice of power systems the most important task facing satellite designers. The main purpose of the Satellite EPS is to provide continuous, regulated and conditioned power to all the satellite subsystems. It has to withstand radiation, thermal cycling and vacuums in hostile space environments, as well as subsystem degradation over time. The EPS power characteristics are determined by both the parameters of the system itself and by the satellite orbit. After satellite separation from the launch vehicle (LV) to its orbit, in almost all situations, the satellite subsystems (attitude determination and control, communication and onboard computer and data handling (OBC&DH)), take their needed power from a storage battery (SB) and solar arrays (SA) besides the consumed power in the EPS management device. At this point (separation point, detumbling mode), the satellite's angular motion is high and the orientation of the solar arrays, with respect to the Sun, will change in a non-uniform way, so the amount of power generated by the solar arrays will be affected. The objective of this research is to select satellite EPS component types, to estimate solar array illumination parameters and to determine the efficiency of solar arrays during both detumbling and normal operation modes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.582-588
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• 1999

정보화 사회의 발전과 함께 멀티미디어에 대한 관심이 집중되고 있으며, 점유 공간이 작고 가벼우며 대면적이 가능한 정보 표시 디스플레이에 대한 기술은 고부가가치 산업으로 인식되어 지고 있다. 이러한 정보 표시 디스플레이들 중, 전기 발광 소자 (Electroluminescence Display : ELD), 액정 표시 디스플레이 (Liquid Crystal Display LCD), 플라즈마 디스플레이 (Plasma Display Panel) 등의 대한 연구가 세계적으로 매우 활발하게 진행되고 있다. 본 연구에서는 란탄 계열의 금속 착 화합물인 Tb(ACAC)$_3$(Phen)과 Tb(ACAC)$_3$(Phen-Cl)를 이용해 다비이스를 제작한후 광학적 및 전기적 특성을 조사하였다. 또한 luminous efficiency와 cyclic voltametric 방법을 이용해 에너지 밴드로 두 발광 물질인 Tb(ACAC)$_3$(Phen)과 Tb(ACAC)$_3$(Phen-Cl)을 비교.분석하였다. 본 연구의 디바이스 구조를 보면 anode/hole transporting layer (HTL)/emitting material layer (EML)/electron transporting layer (ETL)/cathode와 같고 ETL를 aluminum-tris- (8-hydroxyquinoline) (Alq$_3$)와 bis(10-hydroxybenzo(h)quinolinato)beryllium (Bebq$_2$)를 사용하였으며 HTL 로 N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD)를 사용하였다.

• ETRI Journal
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• v.27 no.4
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• pp.405-410
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• 2005

High quality indium tin oxide (ITO) thin films were grown by pulse laser deposition (PLD) on flexible polyethersulphone (PES) substrates. The electrical, optical, and surface morphological properties of these films were examined as a function of substrate temperature and oxygen pressure. ITO thin films, deposited by PLD on a PES substrate at room temperature and an oxygen pressure of 15 mTorr, have a low electrical resistivity of $2.9{\times}10^{-4}{\Omega}cm$ and a high optical transmittance of 84 % in the visible range. They were used as the anode in organic light-emitting diodes (OLEDs). The maximum electro luminescence (EL) and current density at 100 $cd/m^2$ were 2500 $cd/m^{2}$ and 2 $mA/m^{2}$, respectively, and the external quantum efficiency of the OLEDs was found to be 2.0 %.

• Smart Structures and Systems
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• v.6 no.7
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• pp.793-810
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• 2010

This paper addresses the control issue of vibratory MEMS-based gyroscopes. This study considers a gyroscope that can be modeled by an inner mass attached to an outer mass by four springs and four dampers. The outer mass itself is attached to the rotating frame by an equal number of springs and dampers. In order to measure the angular rate of the rotating frame, a driving force is applied to the inner mass and the Coriolis force is sensed along the y-direction associated with the outer mass. Due to micro-fabrication imperfections, including anisoelasticity and damping effects, both gyroscopes do not allow accurate measurements, and therefore, it becomes necessary to devise feedback controllers to reduce the effects of such imperfections. Given an ideal gyroscope that meets certain performance specifications, a feedback control strategy is synthesized to reduce the error dynamics between the actual and ideal gyroscopes. For a dual-mass gyroscope, it is demonstrated that the error dynamics are remarkably decreased with the application of four actuators applied to both masses in the x and y directions. It is also shown that it is possible to reduce the error dynamics with only two actuators applied to the outer mass only. Simulation results are presented to prove the efficiency of the proposed control design.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.77-85
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• 2005

Digital copyright protection is important in the protective side of effort to have leaned to in property right and it which are intelligent of an author and is very important for development of digital contents industry. It is the misgovernment that a reproduction is easy as for the digital contents. and the original and a copy have the same characteristic, and it is so, and is experiencing what is hard for protection of copyright and large quantity illegal copy and illegal distribution prevention. CDN needs a copyright protective plan about the digital contents that digital contents providers were written jointly. The paper used a non-repudiation multi-technique for copyright protection about the digital contents which were written jointly. The Non-repudiation multi-technique proved efficiency about this.

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.433-440
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• 2013

We present an experimental and numerical study of spectral profiles of effective group indices of hydrogenated amorphous silicon (a-Si:H) waveguides and of their chromatic-dispersion effect on the four-wave-mixing (FWM) signal generation. The a-Si:H waveguides of 220-nm thickness and three different widths of 400, 450 and 500 nm were fabricated by using the conventional CMOS device processes on a $2-{\mu}m$ thick $SiO_2$ bottom layer deposited on 8-inch Si wafers. Mach-Zehnder interferometers (MZIs) were formed with the a-Si:H waveguides, and used for precise measurement of the effective group indices and thus for determination of the spectral profile of the waveguides' chromatic dispersion. The wavelength ranges for the FWM-signal generation were about 45, 75 and 55 nm for the 400-, 450- and 500-nm-wide waveguides, respectively, at the pump wavelength of 1532 nm. A widest wavelength range for the efficient FWM process was observed with the 450-nm-wide waveguide having a zero-dispersion near the pump wavelength.