• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.102-109
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• 2013

In this paper, a new torque predictive control method of interior permanent magnet synchronous motor is developed based on an extended rotor flux. Also, a duty ratio prediction method is proposed and allows the duty ratio of the active stator voltage vector to be continuously calculated. The proposed method makes it possible to relatively reduce the torque ripple under the steady state as well as to remain the good dynamic response in the transient state. With the duty ratio prediction method, the magnitude and time interval of the active stator voltage vector applied can be continuously controlled against the varying operation conditions. This paper shows a comparative study among the switching table direct torque control(DTC), the SVM-DTC, conventional torque predictive control, and the proposed torque predictive control. Simulation results show validity and effectiveness of this work.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.407-410
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• 2008

This paper presents a maximum power point tracking(MPPT) of photovoltaic system with duty ratio of DC-DC converter considered load. A variation of solar irradiation is most important factor in the MPPT of PV system That is nonlinear, aperiodic and complicated. NN was widely used due to easily solving a complex math problem. The paper consists of solar radiation source, DC-DC converter, DC motor and load(cf, pump). NN algorithm apply to DC-DC converter through an adaptive control of neural network, calculates converter-duty ratio using an adaptive control of NN. The results of an adaptive control of NN compared with the results of converter-duty ratio which are calculated mathematical modeling and evaluate the proposed algorithm. The experimental data show that an adequacy of the algorithm was established through the compared data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.57-66
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• 2012

When typical Z-source DC/AC inverter(ZSI) is operated in high voltage gain area, because of its high duty ratio, voltage and current stress in Z-network of typical ZSI are increased. This paper proposes a new switched trans ZSI(STZSI) with two switched trans cells which consist of one trans and two diodes. To confirm the operation performance of the proposed system, the PSIM simulation is performed for typical ZSI, switched inductor ZSI and the proposed STZSI. Voltage / current stress and transient state characteristics of each method are compared under the condition of DC input voltage 100[V] and output phase voltage 66[Vrms]. As a result, we confirmed that transient state of the proposed STZSI is short compared with the conventional ZSI because the high voltage gain is obtained using the same duty ratio, also a low duty ratio is required for the same output voltage. Finally, we could know the proposed system have low voltage and current stress in Z-network compared with the conventional ZSI.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.5
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• pp.421-428
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• 2015

An advanced direct torque control (DTC) with pulse width modulation (PWM) method is presented in this paper. The duty ratio calculation of the selected voltage vector is based on the voltage functions of the selected voltage vector according to the sector angle. The proposed DTC uses a conventional DTC scheme with six sector divisions and switching rules. However, the winding voltages are supplied by the PWM approach. Furthermore, the duty ratio of the switching voltage vector is determined by the flux, torque error, and motor speed. The base voltage that shall determine the duty ratio can be calculated by approximate voltage functions according to the voltage angle. For the calculation of base voltages, second-order quadratic functions are used to express the output voltage of the selected voltage vector according to voltage angle. The coefficients for the second-order quadratic functions are selected by the voltage vector, which is determined by the switching rules of the DTC. In addition, the voltage functions are calculated by the coefficients and voltage angle between the voltage vector and rotor position. The switching voltages from the calculated duty ratio can supply the proper torque and flux to reduce the ripple and error. The proposed control scheme is verified through practical experimental comparisons.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.146-150
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• 2004

The effects on non-thermal plasma generation by duty Ratio and frequency of pulse voltage were investigated experimentally. For these, a new type of non-thermal plasma generator with mesh electrode was manufactured and it was possible to generate the surface and silent discharge simultaneously by new type of non-thermal plasma generator. Duty ratio and frequency were selected as main parameters to control the movement of electron which is mainly related to the non-thermal plasma generation. The characteristics of non-thermal plasma generation were investigated indirectly by measuring the I-V curve and quantity of ozone generation. The most effective condition of duty ratio and frequency to generate the non-thermal plasma was identified by experiments with manufactured non-thermal plasma generator.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.307-307
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• 2013

초고집적 회로에 적용되는 반도체 소자의critical dimension (CD)이 수 nano 사이즈로 줄어들고 있기 때문에, 다양한 물질의 식각을 할 때, 건식식각의 중요성이 더 강조되고 있다. 특히 $SiO_2$와 같은 유전체 물질을 식각할 때, plasma process induced damages (P2IDs)가 관찰되어 왔고, 이러한 P2IDs를 줄이기 위해, pulsed-time modulation plasma가 광범위하게 연구되어 왔다. Pulsed plasma는 정기적으로 radio frequency (RF) power on과 off를 반복하여 rf power가 off된 동안, 평균전자 온도를 낮춤으로써, 웨이퍼로 입사되는 전하 축적을 효과적으로 줄일 수 있다. 또한 fluorocarbon plasmas를 사용하여 $SiO_2$를 식각하기 위해 Dual-Frequency Capacitive coupled plasma (DF-CCP)도 널리 연구되어 왔는데, 이것은 기존의 방법과는 다르게 plasma 밀도와 ion bombardment energy를 독립적으로 조절 가능하다는 장점이 있어서 미세 패턴을 식각할 때 효과적이다. 본 연구에서는 Source power에는 60 MHz pulsed radio frequency (RF)를, bias power에는 2 MHz continuous wave (CW) rf power가 사용된 system에서 Ar/$C_4$ F8/$O_2$ 가스 조합으로, amorphous carbon layer (ACL)가 hard mask로 사용된 $SiO_2$를 식각했다. 그리고 source pulse의 duty ratio와 pulse frequency의 효과에 따른 $SiO_2$의 식각특성을 연구하였다. 그 결과, duty ratio의 감소에 따라 $SiO_2$, ACL의 etch rate이 감소했지만, $SiO_2$/ACL의 etch selectivity는 증가하였다. 반면에 pulse frequency의 변화에 따른 두 물질의 etch selectivity는 크게 변화가 없었다. 그 이유는 pulse 조건인 duty ratio의 감소가 전자 온도 및 전자 에너지를 낮춰 $C_2F8$가스의 분해를 감소시켰으며, 이로 인해 식각된 $SiO_2$의 surface와 sidewall에 fluorocarbon polymer의 형성이 증가하였기 때문이다. 또한 duty ratio의 감소에 따라 etch selectivity뿐만 아니라 etch profile까지 향상되는 것을 확인할 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.2
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• pp.191-198
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• 2005

Adding hydrogen gas in natural gas leads to stable combustion in internal combustion engine and its performances rely on compression ratio. To analyze the effects of compression ratio and rate of hydrogen addition on the engine performance, the characteristics of overall engine performance including emission were investigated by using the medium duty natural gas fueled engine. As results, it was found that compression ratio occurred knock was nearby compression ratio, $\varepsilon$=14 for the case that hydrogen was enriched in the natural gas fueled engine. But slight knock was occurred at $\varepsilon$=14.7 in the case of neat natural gas. Also HC and $CO_2$ were reduced around 80% and 20% respectively when the rate of hydrogen addition was increased to 50% and compression ratio from $\varepsilon$=13 to $\varepsilon$=14.7.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.3
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• pp.132-139
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• 1984

This paper presents an exant analysis of the class E tuned power amplifier with a shunt inductor. The following performance parameters are determined for optimum operation with any switch duty ratio: the collector current and voltage waveforms, the peak values of collector current and voltage, the output power, the power output capability, and the values of the load network elements. The analysis shows that the maximum power output capability occurs at a duty ratio of 50 percent. The measured collector efficiency of experiments is 93 percent with 0.93W at 1MHz. This amplifier is especially applicable at portable transmitters because its colletor efficiency is extremely high.

• International journal of advanced smart convergence
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• v.7 no.4
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• pp.19-26
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• 2018

One of the distinct features of Wireless Sensor Networks (WSNs) is duty cycling mechanism, which is used to conserve energy and extend the network lifetime. Large duty cycle interval introduces lower energy consumption, meanwhile longer end-to-end (E2E) delay. In this paper, we introduce an energy consumption minimization problem for duty-cycled WSNs. We have applied Q-learning algorithm to obtain the maximum duty cycle interval which supports various delay requirements and given Delay Success ratio (DSR) i.e. the required probability of packets arriving at the sink before given delay bound. Our approach only requires sink to compute Q-leaning which makes it practical to implement. Nodes in the different group have the different duty cycle interval in our proposed method and nodes don't need to know the information of the neighboring node. Performance metrics show that our proposed scheme outperforms existing algorithms in terms of energy efficiency while assuring the required delay bound and DSR.

• International Journal of Control, Automation, and Systems
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• v.6 no.5
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• pp.660-669
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• 2008

This paper presents a new carrier based pulse-width modulation (PWM) method for matrix converters. By using the concept of average over one switching period, the modulation algorithm and the required equations are derived to synthesize the desired output voltage and to achieve the controlled input power factor. The proposed method uses a continuous carrier and the predetermined duty ratio signals to directly generate the gating signals and, thus, is referred to as "direct duty ratio PWM (DDPWM)". The feasibility and validity of the proposed method were verified by simulation and experiment.