• 조명전기설비학회논문지
• /
• 제29권9호
• /
• pp.81-88
• /
• 2015

LED has been great attentions in lighting industry because of its long life-time, high efficiency, excellent light output characteristics. However, the life-time of the LED driving system is decreased because of the electrolytic capacitor which is used in the power conversion system for driving LED lighting. Therefore the capacitance reduction methods have been studied to replace an electrolytic capacitor with film or tantalum capacitor. This paper presents the Single stage PFC flyback converter with the simplified third harmonic current injection circuit to reduce output capacitance and the proposed system is theoretically analyzed and verified through the experiment.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• 제5B권1호
• /
• pp.20-26
• /
• 2005

Various kinds of practical machines using the single phase induction motor (SPIM) are utilized to control both speed and torque. In particular, the capacitor-run type SPIM has the characteristic that allows the motor torque to be altered by auxiliary capacitance variation. In this study, we manifest an equivalent model having a more simplified configuration, and clarify the relationship between torque and capacitance. Also, we design an experimental controller that is able to perform speed control with ease by the phase angle control of the AC input voltage. Validity of this study is confirmed through the simulation and experimental results obtained.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
• /
• pp.482-484
• /
• 1999

In this paper, we propose a voting method for capacitance measurement. Nowadays the measurement system is changing from analog system to digital system. However, capacitance measurement system has a data error because of the noise. The data of general digital measurement system include an internal and external measurement noises that highly affect to the results. Therefore, this paper proposes data compensation method using voting method. Finally, simulation results are used to demonstrate the efficiency of the proposed method.

• Journal of Electrical Engineering and information Science
• /
• 제2권5호
• /
• pp.129-133
• /
• 1997

A circuit model for a field emission triode has been proposed. The model parameters have been extracted from he fabricated silicon tip array and verified by comparing with the results simulated by circuit simulator(SPICE). The cut-off frequency can be calculated from the parametric capacitance and the transconductance values extracted from measurements. For the field emission triode, the capacitance of 3.45fF/tip and the transconductance of 0.94nS/tip have been measured under the emission current of 4.1nA/tip. From these values, the cut-off frequency is predicted to be 43 kHz but th measured one came out to be 6 kHz. because o the parasitic capacitance components.

• Journal of Electrical Engineering and Technology
• /
• 제7권2호
• /
• pp.212-220
• /
• 2012

In the current paper, the optimization shape of a polysilicon variable-capacitance micromotor (VCM) was determined using the seeker optimization algorithm (SOA). The optimum goal of the algorithm was to find the maximum torque value and minimum ripple torque by varying the geometrical parameters. The optimization process was performed using a combination of SOA and the finite-element method (FEM). The fitness value was calculated via FEM analysis using COMSOL3.4, and SOA was realized by MATLAB7.4. The proposed method was applied to a VCM with eight and six poles at the stator and rotor, respectively. For comparison, this optimization was also performed using the genetic algorithm. The results show that the optimized micromotor using SOA had a higher torque value and lower torque ripple, indicating the validity of this methodology for VCM design.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
• /
• pp.69-72
• /
• 2008

A new electrode structure is proposed in this paper which can increase the discharge efficiency of plasma display panels and also decrease the panel capacitance by decreasing the electrode area effectively. Even with the decreased electrode area, the proposed structure could suppress the requirement for increasing the voltage and improve efficiency by limiting the discharge current.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제1권3호
• /
• pp.189-192
• /
• 2001

A simple metal-insulator-metal (MIM) capacitor in a standard $0.25{\;}\mu\textrm{m}$ digital CMOS process is described. Using all six interconnect layers, this capacitor exploits both the lateral and vertical electrical fields to increase the capacitance density (capacitance per unit area). Compared to a conventional parallel plate capacitor in the four upper metal layers, this capacitor achieves lower parasitic substrate capacitance, and improves the capacitance density by a factor of 4. Measurements and an extracted model for the capacitor are also presented. Calculations, model and measurements agree very well.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 추계학술대회 논문집
• /
• pp.266-266
• /
• 2009

For the development of hybrid supercapacitor, increasing energy density is one of the most crucial matters. Since the energy density is the function of capacitance and voltage, it is necessary to enhance energy density for increasing capacitance or voltage. For the high working voltage, it was to enforce Li ion free-doping to activated carbon. As a result, initial capacitance has increased by 11% than raw cell. But capacitance has decreased by Li ion re-solution to electrolyte for increase the number of cycle.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권10호
• /
• pp.539-545
• /
• 2004

In this paper, we consider the problem of capacitance matrix calculation for strip-line and other interconnects crossings. The problem is formulated in the spectral domain using the method of moments. Sinc-functions are employed as basis functions. Conventionally, such a formulation leads to a large, non-sparse system of linear equations in which the calculation of each of the coefficient requires the evaluation of a Fourier-Bessel integral. Such calculations are computationally very intensive. In the method proposed here, we provide simplified expressions for the coefficients in the moment method matrix. Using these simplified expressions, the coefficients can be calculated very efficiently. This leads to a fast evaluation of the capacitance matrix of the structure. Computer simulations are provided illustrating the validity of the method proposed.

• Transactions on Electrical and Electronic Materials
• /
• 제14권4호
• /
• pp.182-186
• /
• 2013

We studied the possibility that an air capacitor can be used as a humidity sensor by measuring capacitance change. In order to investigate the possibility, the change of capacitance of an air capacitor due to moisture in air was first considered theoretically, and was then experimentally verified. The capacitance was measured by an LCR impedance meter with a 100-kHz and 1-V ac. The results revealed that the changes in the experimentally measured capacitances were greater than those in the theoretically calculated values. Based on this fact, we knew that an air capacitor could be used as part of a humidity sensing device. We expect the humidity sensor with an air capacitor has characteristics of fast response time, high reliability, and high durability compared with other conventional methods.