• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2467-2469
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• 2001

A strategy for the swing-up and stabilization control method for a two-links rotational pendulum according to states of each link of the rotational pendulum is proposed. The proposed controller consists of two modes of control such as divergence mode and stabilization mode. When the controller is in divergence mode, control input is generated using sinusoidal function, which is developed based on resonance period of the pendulum in linear region, to make the second link (pendulum) reach top position. After the controller finishes operation in divergence mode, stabilization control is initiated to keep the pendulum around the top position using pole placement control method. Experimental results are given to show the effectiveness of the proposed method.

• Journal of electromagnetic engineering and science
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• v.17 no.2
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• pp.71-75
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• 2017

A dual-band tunable-slot-type ground radiation antenna is proposed. The feeding structure consists of a coplanar waveguide and a lumped capacitor to excite currents for first- and second-order resonant modes of the ground. The resonant frequencies of both bands are controlled using a series combination of a capacitor and an inductor. The proposed design may be an attractive choice for mobile devices owing to its compact geometry and tunable operating frequencies. The measurement and simulation results of the proposed antenna show good agreement, indicating good impedance matching and radiation performance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.12 s.255
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• pp.1596-1602
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• 2006

In this paper, a hybrid sensor is proposed that has two capabilities: the first is to sense longitudinal or flexural transient vibration signals selectively which are transmitted along the target shaft, and the second to measure the rotating speed of the shaft. All measurements are made in a non-contact manner since this sensor uses magnetostriction as its measuring principle. The signal selection between two vibration modes requires only electrical switching operations and the switching between these two sensing capabilities-vibrations and rotational speed-are accomplished by a very simple mechanical operation. To verify the capabilities of the proposed sensor, a prototype sensor is fabricated and the experiments are made. The results show this sensor can embody two sensing capabilities in one sensor configuration.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1108-1113
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• 2017

In this paper, a bidirectional topology for quasi-Cuk dc/dc converter with capability of zero-voltage and zero-current-switching (ZVZCS) is proposed. The bidirectional quasi-Cuk (BQ-Cuk) converter has different voltage and current transfer ratio, reduced voltage stress on capacitor and capability of changing the output polarity in comparison with conventional bidirectional Cuk converter. In this paper, steady-state analysis of the quasi-Cuk converter with capability of ZVZCS in turn-on is presented. Then, critical inductances for transient from this operation to two new operations are calculated. Next, besides values designing of used elements, maximum and minimum value of their current and voltage are calculated. Finally, experimental results to verify the accuracy of the proposed converter in different operating modes are presented.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.518-522
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• 2004

This paper describes a dynamic UPS system with flywheel energy storage element. There are three operating modes of charging, voltage compensation, and UPS. The operating principle of each mode is analyzed and simulated. The simulation results show the validity of the operation of the proposed scheme.

• Review of KIISC
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• v.3 no.4
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• pp.69-88
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• 1993

이 시리즈를 시작하면서 제3권 제2호(1993.6)에 sc27국제표준화 현황을 정리해 보고했었다. 필자와 산업연구원의 이경석 박사가 1993년 10월 파리에서 열린 SC27 국제표준 총회에 다녀와 새로 정리된 최신의 표준화현황은 11월 20일 개최되는 1993년도 한국통신정보보호학회 학술대회에서 특별보고회로 발표되며그 내용은 논문집에 포함되어 있으니 참고 바란다. 이번 호에는n비트의 입출력을 갖는 블럭암호화 알고리즘의 사용방법에 관해 1991년에 국제표준이 된 문서 IS 10116를 소개한다. 이보다 앞서 1987년 IS 8372로 거의 같은 내용의 국제표준이 n=64의 경우에 한정되어 만들어져 사용되어왔다. 1992년 정보보안 국제총회에서 IS 10116이 IS8372의 내용을 포함하며 IS 10116가 IS 8372보다 더 잘 서술되어 있으므로 IS 3872를 국제표준으로 놓아두자는 결론을 냈었다.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.673-676
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• 2001

In this paper, the improved zero-voltage transition(ZVT) PWM boost converter using an inductor feedback technique is proposed. The improved circuit uses a low-voltage zener diode to reduce the turn-off witching loss of the auxiliary witch and EMI noise. Using this technique, soft-witching for the auxiliary switch is guaranted at wide line and load ranges and some of the energy circulating in the auxiliary circuit is fed to the load Since the active switches are turned on and off softly, the witching losses and EMI noise are reduced significantly and the higher efficiency of the system is achieved. In this paper, the modes of converter operation are explained and analyzed, design guidelines are given, and experimental results of 1kW, 100kHz prototype system are presented.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.548-551
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• 2001

A zero-voltage transition (ZVT) PWM boost PFC converter using a transformer to recover the resonant energy into the input voltage is proposed. The proposed converter reduces turn-off switching loss of the auxiliary switch. The resonant current of the auxiliary circuit is optimally reduced by the feed-forwarded input voltage. Moreover, the resonant energy of the auxiliary circuit is recovered into the load and input voltages. In this paper, the modes of converter operation are explained and analyzed, design guidelines are given, and experimental results of 1.2kW, 200kHz prototype system are presented.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.252-255
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• 1987

High performance requirements such as high speed operation. accuracy and versatility have led to the consideration of structural flexibility in robot arms. The purpose of this study is to investigate the interrelationships between the robot structural flexibility and a linear controller for the rigid body motion. This paper employs an assumed modes method to model both the rigid and flexible motion of the robot arm. The simulation results illustrate the differences between leadscrew driven and unconstrainted axes of the robot.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.797-800
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• 1987

A new current control scheme is suggest.ed which is suitable for ac servo inverter drives. The scheme uses a simple block diagram to produce the reference stator voltage vector, and the vector nearest to it is chosen for switching. With the same arrangment three kinds of operation modes are possible : (1) constant rate sampling, (2) constant current deviation, (3) adaptive current deviation. In mode (1) current deviation after one period is minimized, while in mode (2) and (3) intervals between switchings are maximized.