• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.3
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• pp.73-76
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• 2003

In modern EHV (Extra High Voltage) class GCBs (Gas Circuit Breakers), the interruption capability for SLF (Short Line Fault) is one of the most important aspects of performance required for GCBs. Up to now, the SLF interruption capability of EHV class GCBs was partially assisted by the adoption of capacitors able to decrease the dV/dt of the TRV (Transient Recovery Voltage), particularly the TRV on the line side. This paper describes the technique to increase the SLF interruption capability of EHV class GCBs as well as the procedure to develop capacitorless l70kV 50kA GCB.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.905-908
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• 2005

본 논문에서는 class AB opamp 를 채용한 384kHz differential PWM 신호를 입력으로 하는 2-channel stereo audio amplifier 블록을 공급전압 3.3V 조건에서 SMIC 0.18um thick oxide 기술을 이용하여 설계한다. 여기서 class AB opamp 는 공정 변화에 따른 quiescent current가 변하는 것을 최소화하기 위하여 adaptive load 를 사용하며, 전체적으로는 3 차 Butterworth lowpass filter 와 differential-to-single converter 로 구성된 2 개의 audio amplifier 와 출력전압이 ${\frac{1}{2}}Vdd$ 인 common output 블록으로 구성된다. 이러한 설계를 통하여 32ohm 의 저항 load 를 구동할 수 있는 -60dB THD, 전체 quiescent current 2mA 대인 CMOS class AB stereo audio amplifier 를 구현하였다.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.143-152
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• 2004

Recently, software programming method based on EJB for object oriented software design and implement has been used frequently. Usually, case that use permanent data that use Database in EJB base application is most. Part connected with Database-Access that take charge in Entity Bean class of server side creation program. In this paper using J2EE relationship DAO pattern class each separate. This is no much difference with existent pattern method, but in same pattern common classes are designed so that composition may be possible. And as well as use Entity Bean class that created each DBMS classes are different, is doing Rata Source so that connection work is available without alteration or creation of additional program in several DBMS environments.

• Journal of dental hygiene science
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• v.20 no.2
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• pp.118-124
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• 2020

The purpose of this comparison of case reports is to introduce the results of the application of new devices for the management of growing Class III malocclusions in children. Two 8-year-old boys had a chief complaint of anterior crossbite. Anterior crossbite correction using a tandem traction bow appliance (TTBA) or a Carriere Motion 3D Class III appliance with a Transforce appliance was planned. By comparing cephalometric radiographs before and after treatment, changes in skeletal growth and incisor inclination to the Frankfort horizontal (FH) plane could be measured. Both devices increased SNA and ANB angles, N-I Pg-A, U1 to SN, and U1 to FH. Both appliances improved facial features and resolution of anterior crossbite. The TTBA and Carriere Motion 3D Class III appliance had similar effects when applied as early treatment for growing mesio-occlusions and anterior crossbite in two boys. However, long-term outcome assessments and well-designed comparative studies are still required.

• The korean journal of orthodontics
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• v.21 no.1 s.33
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• pp.171-183
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• 1991

This investigation was designed to categorize Angle's class II malocclusion groups through analyzing horizontal and vertical components of craniofacial skeleton in Angle's class II malocclusion. The material selected for this study consisted in standard lateral cephalogram of two hundred and twenteen children, eighty eight boys and one hundred twenty four girls, aged 6 through 18 years, having Angle's class II malocclusion. On the basis of findings of this study, the following results were obtained. 1. In horizontal skeletal classifications, 16 groups were classified according to FMN-A-B, SE-FMN-A, Ba-SE-Me, Ba-Se/Ra P. The sequences that have relatively high frequency are as follows: a) Horizontal Group 16 b) Horizontal Group 12 c) Horizontal Group 13 d) Horizontal Group 9 & 15 2. In vertical skeletal classification, 8 groups were classified according to the PMV/PP, PMV/Occ. P. PMV/Mn. P. The sequences that relatively high frequency are as follows; a) Vertical Group A b) Vertical Group D c) Vertical Group C d) Vertical Group H 3. In vertical and horizontal skeletal classifications, the sequence that relatively high frequency are as follows; a) Group13-A b) Group16-A & 9-A c) Group12-A & 15-A d) Group16-C

• Journal of Power Electronics
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• v.15 no.1
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• pp.65-77
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• 2015

Resonant converters are well suited for induction heating (IH) applications due to their advantages such as efficiency and power density. The control systems of these appliances should provide smooth and wide power control with fewer losses. In this paper, a simple phase locked loop (PLL) based variable duty cycle (VDC) pulse density modulation (PDM) power control scheme for use in class-D inverters for IH loads is proposed. This VDC PDM control method provides a wide power control range. This control scheme also achieves stable and efficient Zero-Voltage-Switching (ZVS) operation over a wide load range. Analysis and modeling of an IH load is done to perform a time domain simulation. The design and output power analysis of a class-D inverter are done for both the conventional pulse width modulation (PWM) and the proposed PLL based VDC PDM methods. The control principles of the proposed method are described in detail. The validity of the proposed control scheme is verified through MATLAB simulations. The PLL loop maintains operation closer to the resonant frequency irrespective of variations in the load parameters. The proposed control scheme provides a linear output power variation to simplify the control logic. A prototype of the class-D inverter system is implemented to validate the simulation results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.81-86
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• 2007

In this paper, the Power Added Efficiency (PAE) and linearity of class-F PA has been improved by using the PBG structure and the application of EER structure, simultaneously. The adaptive bias control circuit has been employed to improve the PAE through the application of EER structure. The PBG structure has been adapted for improving the Linearity by suppressing the harmonics on the output of amplifier. The PAE and the 3rd Inter-Modulation Distortion (IMD) has improved 34.56%, 10.66 dB, compared with those of the conventional Doherty amplifier, respectively.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.81-86
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• 2005

In this paper, we present an efficiency extension of Doherty power amplifier using LDMOS FET devices with different peak output powers and an unequal power divider. The amplifier is designed by using a MRF21045 with P1 dB of 45 W as the main amplifier biased for Class-AB operation and a MRF21090 with P1 dB of 90 W as the peaking amplifier biased for Class-C operation. The input power is divided into a 1:1.5 power ratio between the main and peaking amplifier. The simulated results of the proposed Doherty amplifier shows an efficiency improvement of approximately 19 % in comparison to the class-AB amplifier at an output power of 42.5 dBm. The fabricated Doherty amplifier obtained a PAE of 33.68 % at 9 dB backed off from P1 dB of 51.5 dBm.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.149-156
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• 2012

A digital input class-D audio amplifier is presented for digital hearing aid. The class-D audio amplifier is composed of digital and analog circuits. The analog circuit converts a digital input to a analog audio signal (DAC) with noise suppression in the audio band. An interpolated digital delta-sigma modulator is used to convert data types between digital signal processor (DSP) and digital-to-analog converter (DAC). An 16-bit, 25-kbps pulse code modulated (PCM) input is interpolated to 16-bit, 50-kbps by a digital filter. The output signal of interpolation filter is noise-shaped by a third-order digital sigma-delta modulator (SDM). As a result, 1.5-bit, 3.2-Mbps signal is applied to simple digital to analog converter.

• Journal of Navigation and Port Research
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• v.30 no.5 s.111
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• pp.351-356
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• 2006

In this paper, the high efficiency Doherty power amplifier has been designed and realized for microwave applications. The Doherty amplifier has been implemented using silicon MRF 281 LDMOS FET. The RF performances cf the Doherty power amplifier (a combination of a class AB carrier amplifier and a bias-tuned class C peaking amplifier) have been compared with those of a class AB amplifier alone. The realized Doherty power amplifier P1dB output power has 33dBm at 2.3GHz frequency. Also the Doherty power amplifier shows 11dB gain and -17.8dB input return loss at 2.3GHz to 2.4GHz. The designed Doherty amplifier has been improved the average PAE by 10% higher efficiency than a class AB amplifier alone. The Maximum PAE of designed Doherty power amplifier has been 39%.