• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2395-2397
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• 2005

A low voltage operated piezoelectric RF MEMS in-line switch has been realized by using silicon bulk micromachining technologies for advanced mobile/wireless applications. The developed RF MEMS in-line switches were comprised of four piezoelectric cantilever actuators with an Au contact metal electrode and a suspended Au signal transmission line above the silicon substrate. The measured operation dc bias voltages were ranged from 2.5 to 4 volts by varying the thickness and the length of the piezoelectric cantilever actuators, which are well agreed with the simulation results. The measured isolation and insertion loss of the switch with series configuration were -43dB and -0.21dB (including parasitic effects of the silicon substrate) at a frequency of 2GHz and an actuation voltage of 3 volts.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1531-1532
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• 2006

Recently, the natural environment changes drastically, and the frequency of occurrence for lightning has gradually been increased. Such lightning delivers high volume of energy along the power line and communication line to the equipment in use. The high volume of energy arising from the lightning surge develops in fast velocity to destroy the facilities in power source and many other facilities in operation in sequential destruction with vast energy. In this thesis, the analysis on the change of clamping voltage characteristics by the contact resistance and lead inductance by using several case studies through the application of element for preventing the short circuit of Metal Oxide Varistor for ZnO.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2025-2027
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• 2005

Thermal conductive polymer film was adopted to reduce the fracture of module during the fabrication of thermoelectric generator. We investigated the thermoelectric output power of module with the change of thickness of polymer film, direct contact and thermal-conductive grease. It is measured that thermoelectric output power is decreased with the increasing thickness of thermal-conductive polymer film. And

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1272-1274
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• 1996

This paper presents the development of tactile sensor systems for robot hand which are truly usable, robust, reliable and cheap system. The sensor incorporates multiple sensing subsystems for detecting distributed contact forces and surface characteristics. The fabrication and experimental evaluation of the tactile system and its electric interfaces are described. The results indicate that the system provides reasonable performances for practical applications requiring manipulation with tactile feedback.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.732-734
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• 2003

In this paper, a design of horizontal-type 5DOF magnetic bearing is presented. To implement the non-contact bearing, an active magnetic bearing using electromagnet is used and finite element method(FEM) is chosen to design the bearing magnet. Two radial bearing and one thrust bearing is designed to implement 5DOF operation. And three-phase induction motor is used as a driving motor. The design method for the magnetic bearing system is described.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1202-1204
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• 2003

최근, 이동용 무선통신기기 지원 기기국내 전원인가용 DC/DC 컨버터 시스템의 상시 상태감시 및 수영평가를 위해, 기본 동작책무인 고속연산에 의한 신호변환과 더불어 원격온라인으로 데이터통신이 가능한 광역진단용 DC/DC 컨버터의 임베디드 시스템 개발에 대해서 기술하고자 한다.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.85-87
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• 2003

본 논문은 2기 5모선 모의계통에 3상 단락고장을 발생시킬 경우, 해당 모선에서 각 차단기가 분담하는 고장전류를 PSCAD/EMTBC3.0을 이용하여 분석한 결과이다. 적용된 차단기 개극시간(Contact Parting Time, CPT) 및 아크시간(Arc Time) 등은 실제 차단기 제작사(효성, 현대중공업 및 LG산전)들로부터 조사/수집하여 적용하였으며, 적용 대상계통은 PSS/E 분석결과와 비교/검토하여 검증하였다. 이는 기존 혹은 신설 차단기 적정 차단용량을 선정하는데도 활용가능 할 것으로 보인다.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.248-250
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• 2004

We have investigated the surface state of 154kV polymeric insulators exposed to in-service conditions for about five years. In order to evaluate surface aging of silicone rubber exposed to real field environments, we used various analytic methods such as contact angle, ATR-FTIR, SEM-EDS. Although contaminants were accumulated on weathershed surface, polymeric insulator has retained its intrinsic surface hydrophocity. In addition, ATR-FTIR confirmed the diffusion layer of a low molecular weight silicone fluid on surface layer and no surface cracking and chalking were Indicated by SEM. Polymeric insulators have still retained their improved pollution performance over porcelain insulators. That will lead to very low frequency of flashovers throughout their useful life, often under contaminated conditions.

• Journal of Sensor Science and Technology
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• v.19 no.4
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• pp.320-327
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• 2010

In this paper, electrostatically actuated direct contact type RF MEMS switches have been designed and demonstrated. As driving structures of the switch, cantilever, bridge, and torsion spring beam structures are used and the actuation voltage characteristics of the switches have been compared and discussed. The designed RF switches are fabricated with the surface micromachining technology using the electroplated gold and nickel structures. The characteristics of the fabricated switches are measured and analyzed. The switch, which is fabricated using the 510 ${\mu}m$-length bridge structure with the thickness of 1.5 ${\mu}m$, is actuated with 15 V driving voltage. The insertion losses are less than 0.2 dB over the measured frequency ranges from 0 to 20 GHz and the isolations are more than 30 dB.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.42-46
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• 2005

The static electricity by thinner flow and discharge energy is investigated experimentally for the purpose of preventing the electrostatic discharge and damage. Test system for evaluating streaming electrification consists of a teflon pipe, a reservoir tank a pump, flowmeters and an electrometer. When dielectric liquid flows through a pipe from one vessel to another, the potential difference generated in the collecting vessel is due to the accumulation of charges. These charges result from the convection of a part of the electrical double layer existing in the tube at the contact between the liquid and the inner wall. When the fluid velocity increases, the electric current increases proportionally. The charging current and accumulated charges by streaming electrification at the thinner velocity of 40cm/s are measured a range of 5 nA and $0.27{\mu}C$ respectively. This amount of static discharge energy generated by streaming electrification is enough to ignite flammable solvent. Therefore surface electric potential should decrease by using electrostatic shielding and ground.