• Journal of Internet of Things and Convergence
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• v.6 no.1
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• pp.97-102
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• 2020

Multi-Channel Switch ICs for IoT have integrated several solid state structure low ON-resistance bi-directional relay MOS switches with level shifter to drive high voltage and they should be independently controlled by external serialized logic control. These devices are designed for using in applications requiring high-voltage switching control by low-voltage control signals, such as medical ultra-sound imaging, ink-jet printer control, bare board open/short and leakage test system using Kelvin 4-terminal measurement method. This paper describes implementation of analog switch control block and its verification using Field programmable Gate Array (FPGA) test pattern generation. Each block has been implemented using Verilog hardware description language then simulated by Modelsim and prototyped in a FPGA board. Compare to conventional IC, The proposed architecture can be applied to fields where multiple entities need to be controlled simultaneously in the IoT environment and the proposed pattern generation method can be applied to test similar types of ICs.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.256-256
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• 2015

이산화 바나듐 ($VO_2$)은 340 K 임계온도를 기점으로 금속-절연체 상전이를 통해 전기적, 광학적 특성이 가역적으로 변하는 물질로 잘 알려져 있다. 그러나 낮은 가시광 투과율과 비선호적인 색상(황갈색)으로 인해 열변색 스마트 창호응용과 관련하여 해결해야 할 문제로 남아있다. 본 연구에서는 상기 문제를 해결하고자 고분자 나노 구 템플릿을 응용하여 2차원의 벌집구조를 갖는 $VO_2$ 박막을 졸 겔 방법을 통해 제작하였으며 가시광 투과율 향상을 유도하였다. 나노 구의 지름과 코팅조건에 따라 구조변화를 유도하였으며 FE-SEM과 AFM을 통해 박막의 구조적 변화를 측정하였다. 결과로부터 나노 구의 역상모양을 갖는 박막이 형성 되었으며 직경에 따라 패턴 간격이 확연하게 변화되었음을 확인 하였다. 나노 구가 위치하고 있던 자리로부터 빈 공간형성을 유도할 수 있었으며 이는 가시광 투과율향상에 직접적 영향을 주었다. 또한 상기 패턴화된 $VO_2$ 박막은 광학 스위칭 효율을 유지하면서 주기적 패턴으로부터 시각적으로 광결정유도를 통한 미적 시너지를 보였며 본 연구로부터 $VO_2$기반 스마트 창호 응용에 많은 기여가 기대된다.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.395-403
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• 2006

This paper has proposed a new dead time compensation method for a voltage-fed PMW inverter. In the voltage-fed PMW inverter, a voltage distortion is generated by the dead time effect and the nonlinear characteristics of the switching devices. Especially, the distorted voltage causes 5th and 7th harmonics in the stationary phase currents, and 6th harmonic in the synchronous phase currents. As a result, the integrator output of the synchronous PI current regulator has the ripple corresponding to six times of the inverter output frequency. In this paper, the signal of the integrator output of the d-axis current regulator is used as the control signal for the dead time compensation. The experimental and simulation results are presented to verify the validity of the proposed method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.798-804
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• 2013

In this paper, conducted emission from the LDC(Low-Side DC/DC Converter) of a HEV/EV was analyzed using high-frequency circuit modeling in system-level approach. The conducted emission by PWM process(100 kHz; Switching Frequency) can cause RFI(Radio-Frequency Interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a high-frequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of MOSFETs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the LDC. Using these circuit models, results of both simulation and measurement were compared and similarities between them were verified. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.882-889
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• 2010

Semi-active vibration control is one of the attractive control methods for space application due to its robustness as passive damping system and much higher damping performance than passive system. However, a chattering induced by the sudden variation of damping force at the time of On-Off switching of semi-active control device degrades pointing performance of the on-board payload. In this paper, to enhance the pointing performance of the on-board payload, we proposed a semi-active vibration isolation with a strategy for attenuating chattering effect. Numerical simulation results using simplified analysis model indicated that the proposed semi-active control strategy produced much better isolation performance than the conventional Bang-Bang control semi-active control laws derived from skyhook and LQ theories.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.1
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• pp.35-43
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• 2002

In the last decade, considerable efforts have been made to make a new class of solid state high power, high speed electronic device, namely, the Photo-Conductive Power Switch(PCPS), and to characterize the high-field performance of PCPS under high power, high voltage conditions. But the problem of surface flashover phenomena persist, preventing the realization of reliable and efficient high-speed, high voltage switching devices. It is essential to have a clear understanding on the physical processes behind the surface flashover problem to develop new technologies and device architectures so as to fabricate PCPS that are capable of high-field high-voltage. Also, it is imperative to identify new materials that could satisfy the requirements for high-field, high-power devices. Since surface flashover, surface breakdown phenomena is observed for all the devices that foiled at the applied field much lower than semiconductor bulk breakdown field, surface passivation is considered one of the important practical methods to improve the high field performance of the devices. Therefore, this paper was studied the main properties and mechanism of the semiconductor surface flashover before and after passivation under high electric-field.

• Journal of Korea Multimedia Society
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• v.7 no.9
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• pp.1233-1239
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• 2004

In a speech coding system using excitation source of voiced and unvoiced, it would be involved a distortion of speech qualify in case coexist with a voiced and an unvoiced consonants in a frame. This paper present a new multi-pulse coding method by using V/S/TSIUVC switching, individual pitch pulses and TSIUVC approximation-synthesis method in order to restrict a distortion of speech quality. The TSIUVC is extracted by using the zero crossing rate and individual pitch pulse. And the TSIUVC extraction rate was 91% for female voice and 96.2% for male voice respectively. The important thing is that the frequency information of 0.347kHz below and 2.813kHz above can be made with high quality synthesis waveform within TSIUVC. I evaluate the MPC use V/UV and the FBD-MPC use V/S/TSIUVC. As a result, I knew that synthesis speech of the FBD-MPC was better in speech quality than synthesis speech of the MPC.

• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.270-281
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• 2003

ETF made the RFCs of MPLS technologies for providing the QoS of ATM or Frame Relay and the flexibility&scalability of IP on the Internet services. IETF has been expanding MPLS technologies as a common control component for supporting the various switching technologies called GMPLS. Also, IETF has standardized the signaling protocols based on such technologies, such as LDP, CR-LDP and RSVP-TE. ETRI developed the MPLS system based on ATM switch in order to provide more reliable services, differentiated services and value-added services like the VPN and traffic engineering service on the Korea Public Sector network. We are planning on deploying model services and commercial services on that network. This paper explains the basic functions of LDP, design and development of LDP on our system, and compares with LDP development and operation on other MPLS systems made by Cisco, Juniper, Nortel and Riverstone. In conclusion, this paper deduces the future services and applications by LDP through these explanation and comparison.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.8
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• pp.6-14
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• 2006

This paper is a study about a proper method of plasma generation to cleaning method and a high frequency power equipment circuit to generation of plasma that used cleaning of chamber for TFT-LCD PECVD. The high density plasma required for cleaning causes a possibility of high density plasma more than $1{\times}10^{11}[EA/cm^3]$. It apply a ferrite core of ferromagnetic body to a existing ICP form. In case of power transfer equipment on 400[kHz] high frequency to generation of plasma it makes certain a stable switching operation in condition of plasma through using a inverter form for general purpose HB. And it demonstrates the performance of power transfer equipment using methods of measurement which use a transformer of series combination the density of plasma and the rate of dissolution of $NF_3$ in condition of $A_r\;and\;NF_3$.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.99-106
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• 2003

This paper presents a novel multilevel PWM inverter employing series-connected transformers in order to improve the waveshape of output voltage and to reduce its harmonics. The proposed 11-level inverter consists of three full-bridge inverter modules and their corresponding transformers. Among their inverter modules, one is used as PWM operation and the others as level generation. From a suitable selection of turns ratio of transformer, continuous output voltage levels were generated appearing an integral ratio to input DC source. Because of their series connection of transformers, output filter inductor is not necessary. The operational principles and analysis are explained, and it is compared with a conventional multilevel PWM inverter. The validity of the proposed system Is verified through the experimental results using a prototype.