• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04a
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• pp.155-158
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• 2000

Influence of sustain pulse-width on electro-luminous efficiency is experimentally investigated for surface discharge of AC-PDP. A square pulse with variable duty ratio and rising time of 300 ns has been used in the experiment. It is found that the firing voltage is decreased as the pulse-width is increased from 2 ${\mu}s$ to 8 ${\mu}s$ with sweeping frequency range of 10 kHz to 50 kHz. It has been found that the optimal sustain pulse-width is in the range of $3{\sim}4{\mu}s$ under driving frequency range of 30 kHz and 50 kHz, based on observation of memory coefficient, wall charge, and wall voltage as well as luminous efficiency.

• Transactions on Electrical and Electronic Materials
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• v.6 no.6
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• pp.276-279
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• 2005

Influences of sustain pulse-width on electrical characteristics and luminous efficiency are experimentally investigated for surface discharge of AC-PDP. A square pulse with variable duty ratio and fixed rising time of 300 ns has been used in the experiment. It is found that the memory coefficient is significantly increased at the critical pulse-width. And the wall charges and wall voltages as well as capacitances are experimentally measured by Q- V analysis method along with the voltage margin relation, in terms of the sustain pulse-width in the range of $1{\mu}s$ to $5{\mu}s$ under driving frequency of 10 kHz to 180 kHz. And the luminous efficiency is also experimentally investigated in above range of sustain pulse-width with driving frequency of 10 kHz to 180 kHz. It is noted that the luminous efficiency for 10 kHz and 180 kHz are 1.29 1m/W and 0.68 1m/W respectively, since the power consumption for 10 kHz is much less than that for 180 kHz. It has been concluded that the optimal sustain pulse-width is in the range of $2.5 {\~}4.5{\mu}s$ under driving frequency range of 10 kHz and 60 kHz, and in the range of $1.5 {\~} 2.5{\mu}s$ under driving frequency range of 120 kHz and 180 kHz based on observation of memory coefficient, and wall voltage as well as luminous efficiency.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.501-512
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• 2018

Radio frequency identification (RFID) sensor tag provides several advantages including battery-less operation and low cost, which are suitable for long-term monitoring. This paper presents a self-powered RFID temperature sensor tag for online temperature monitoring in substation. The proposed sensor tag is used to measure and process the temperature of high voltage equipments in substation, and then wireless deliver the data. The proposed temperature sensor employs a novel phased-locked loop (PLL)-based architecture and can convert the temperature sensor in frequency domain without a reference clock, which can significantly improve the temperature accuracy. A two-stage rectifier adopts a series of auxiliary floating rectifier to boost its gate voltage for higher power conversion efficiency. The sensor tag chip was fabricated in TSMC $0.18{\mu}m$ 1P6M CMOS process. The measurement results show that the proposed temperature sensor tag achieve a resolution of $0.15^{\circ}C$/LSB and a temperature error of $-0.6/0.7^{\circ}C$ within the range from $-30^{\circ}C$ to $70^{\circ}C$. The proposed sensor tag achieves maximum communication distance of 11.8 m.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.4
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• pp.181-185
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• 2013

This paper deals with the electromagnetic loss characteristics of enclosures for a 24kV high voltage switchgear by using a finite element method (FEM). A study on the electromagnetic characteristics of enclosures for a high voltage switchgear should be conducted to minimize the size and the temperature rising of a switchgear. Generally, the enclosures made by stainless steel are used to minimize the eddy current loss caused by the transporting current in Bus bars due to its non-magnetic characteristics although the price of stainless steel is expensive compared with other metal for enclosures. Therefore, a switchgear made by stainless steel enclosures could be fabricated as a small size and are applied to a switchgear in urban substations. On the contrary, the switchgear enclosures made by steel could be fabricated with relatively cheap manufacturing price. However, the temperature easily rises due to the transporting current in Bus bars because steel is a ferromagnetic material. Therefore, the size of a switchgear made by steel enclosures is relatively massive and installed in rural substations. In this paper, the electromagnetic losses in the enclosures of a switchgear according to various enclosure thicknesses are calculated and compared with each other. Especially, we proposed a hybrid type enclosures for a switchgear made by stainless steel (top and bottom enclosure) and steel (left and right enclosure). It is concluded that the cost electromagnetic performance of applying the hybrid type enclosure is favorable to develop a high voltage switchgear.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.569-575
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• 2020

Recently, research on renewable energy technologies has come into the spotlight due to rising concerns over the depletion of fossil fuels and greenhouse gas emissions. Demand for portable electronic and wearable devices is increasing, and electronic devices are becoming smaller. Energy harvesting is a technology for overcoming limitations such as battery size and usage time. In this paper, the V-I characteristic curve and internal resistance of thermal electric devices were analyzed, and MPPT control methods were compared. The Perturbation and Observation (P&O) control method is economically inefficient because two sensors are required to measure the voltage and current of a Thermoelectric Generator(TEG). Therefore, this paper proposes a new MPPT control method that tracks MPP using only one sensor for the regulation of the output voltage. The proposed MPPT control method uses the relationship between the output voltage of the load and the duty ratio. Control is done by periodically sampling the output voltage of the DC-DC converter to increase or decrease the duty ratio to find the optimal duty ratio and maintain the MPP. A DC-DC converter was designed using a cascaded boost-buck converter, which has a two-switch topology. The proposed MPPT control method was verified by simulations using PSIM, and the results show that a voltage, current, and power of V=4.2 V, I=2.5 A, and P=10.5 W were obtained at the MPP from the V-I characteristic curve of the TEG.

• Clean Technology
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• v.28 no.3
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• pp.227-231
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• 2022

The demand for high-voltage power devices is rising in various industries, but especially in the transportation industry due to autonomous driving and electric vehicles. IGBT module parts of 3.3 kV or more are used in the power propulsion control device of electric vehicles, and the procurement of these parts for new construction and maintenance is increasing every year. In addition, research to optimize high-voltage IGBT parts is urgently required to overcome their very high technology entry barrier. For the development of high-voltage IGBT devices over 3.3 kV, the resistivity range setting of the wafer and the optimal conditions for major unit processes are important variables. Among the manufacturing processes to secure the optimal junction depth, the optimization of the diffusion process, which is one step of the unit process, was examined. In the diffusion process, the type of gas injected, the injection time, and the injection temperature are the main variables. In this study, the range of wafer resistance (Ω cm) was set for the development of high voltage IGBT devices through unit process simulation. Additionally, the well drive in (WDR) condition optimization of the diffusion process according to temperature was studied. The junction depth was 7.4 to7.5 ㎛ for a ring pattern width of 23.5 to25.87 ㎛, which can be optimized for supporting 3.3 kV high voltage power devices.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.128-135
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• 2013

This paper presents a high dimming ratio Power-LED driver IC with high power which is capable of controlling LEDs. In order to accomplish a high dimming ratio LED driver, the preloading inductor current methodology is proposed for the power stage of the proposed method to achieve the fast transient response time during the Power-LED load switching. The information containing the current flowing on the LEDs can be utilized to predict the amount of the current on the inductor. The minimum LED current rising time of existing high dimming ratio Power-LED driver is limited by $3{\mu}s$, however that of the proposed high dimming ratio Power-LED driver is reduced about 1/10. The LED driver is implemented with 0.35um 60V BCDMOS 2-poly 4-metal process. The measurement results show that the proposed LED driver system features the minimum rising time as small as 240ns at the dimming frequency of 1KHz with a 12V of input voltage, nine white LEDs and 353mA of LED current. The LED rising time and power conversion efficiency of the chip are measured to be 240ns and 93.72%, respectively.

• 전기의세계
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• v.22 no.5
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• pp.19-32
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• 1973

This paper treats with some of plasma jet behaviors under magnetic field for the purpose of controlling important characteristics of plasma jet in the practices of material manufacturings. Under the existence and non-existence of magnetic field, the pressure distribution, flame length, stability and noise of plasma jet are comparatively evaluated in respect of such parameters as are current, gap of electrode, quantity of argon flow, magnetic flux density, diameter and length of nozzle. The results are as follows: 1) the pressure, the length and the noise of plasma jet rise gradually with the increase of are current, and have high values under identical arc current as the diameter of nozzle increases, but reverse phenomenon tends to appear in the noise. 2) The pressure, the flame length and the noise increase with the increased quantity of argon flow, and the rising slope of noise is particularly steep. Under magnetic field, the quantity of argon flow in respect of flame length has the critical value of 80(cfh). 3) The pressure and length of flame decrease with small gradient value as the length of gap increases, but the noise tends to grow according to the increase of nozzle diameter. 4) The pressure and the length of jet flame decrease inversly with the increase of magnetic flux density, which have one critical value in the 100 amps of arc current and two values in 50 amps. The pressure of jet flame can be below atomospher pressure in strong magnetic field. 5) "The constriction length of nozzle has respectively the critical value of 6(mm) for pressure and 23(mm) for the length of flame. 6) Fluctuations in the wave form of voltage become greater with the increase of argon flow and magnetic flux density, but tends to decrease as arc current increases, having the frequency range of 3-8KHz. The wave form of noise changes almost in parallel with that of voltage and its changing value increases with argon flow, arc current and magnetic flux density, having the freuqency range of 6-8KHz. The fluctuation of jet presurre is reduced with the increase of argon flow and magnetic flux density and grows with arc current.rent.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.90-99
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• 2004

High speed info-communications equipment are required with development of highly information-oriented society, the intelligent industrial facilities and social systems such as administrative, financial and traffic systems, are gradually becoming to automation, which are composed of the integrated circuits and micro-semiconductors, remote control and operation. Thus modern micro-electronic circuits can frequently be damaged by lightning surge. The protection of electronic circuits from lightning overvoltages is concentrated very interesting. In this paper, for the purpose of providing the effective protection method of electronic devices such micro-computers from lightning surges in a residential building, the protection effect of surge protective devices according to types of system groundings were experimentally analyzed. Also the effective installation method of surge protective devices was examined and proposed. The installation of SPDs in retrofits was a high remnant voltage across the protected device owing to the inductance in the long wires to the SPDs. Finally the method of installing the SPD by twisted pain wires is remarkably effective for fast rising transient overvoltages.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.1
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• pp.59-65
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• 2012

A study on the electrical characteristic analysis of solar cell diodes under experimental conditions of varying temperature and frequency has been conducted. From the current-voltage (I-V) measurements, at the room temperature, we obtained the ideality factor (n) for Space Charge Region (SCR) and Quasi-Neutral Region (QNR) of 3.02 and 1.76, respectively. Characteristics showed that the value of n (at SCR) decreases with rising temperature and n (at QNR) increases with the same conditions. These are due to not only the sharply increased SCR current flow but the activated carrier recombination in the bulk region caused by defects such as contamination, dangling bonds. In addition, from the I-V measurements implemented to confirm the junction uniformity of cells, the average current dispersion was 40.87% and 10.59% at the region of SCR and QNR, respectively. These phenomena were caused by the pyramidal textured junction structure formed to improve the light absorption on the device's front surface, and these affect to the total diode current flow. These defect and textured junction structure will be causes that solar cell diodes have non-ideal electrical characteristics compared with general p-n junction diodes. Also, through the capacitance-voltage (C-V) measurements under the frequency of 180 kHz, we confirmed that the value of built-in potential is 0.63 V.