• 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.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.67-70
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• 2006

This paper deals with a single crystalline silicon (SCS) RF MEMS switch for telecommunication system applications. The proposed SCS switch was fabricated using a silicon-on-glass (SiOG) process and its performances in terms of RF responses, switching time, lifetime were characterized. The proposed SCS switch consists of movable plates, mechanical spring structures, which are composed of robust SCS, resulting in mechanically good stability, The measured actuation voltage was 30 V, and with this applied voltage, the insertion loss and isolation characteristics were measured to be 0.05 and 44.6 dB at 2 GHz respectively. The measured switch ON and OFF time were 13 and $9{\mu}s$, respectively. The lifetime of the fabricated switch was tested. Even after over 1 billion cycles repeated ON/OFF actuations, the switch maintained its own characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1113-1119
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• 2013

In this letter, a new approach is proposed for the design of a multi antenna for MIMO wireless devices. The proposed antenna covers various LTE(Long Term Evolution) service bands: band 17(704~746 MHz), band 13(746~787 MHz), band 5(824~894 MHz), and band 8(880~960 MHz). The proposed main antenna consists of a conventional monopole antenna with an inverted L-shaped slit for wideband operation. The proposed the LTE sub antenna is based on a switch loaded loop antenna structure, with a resonance frequency that can be controlled by capacitance of a logic circuit. The tuning technique for the LTE Rx antenna uses a RF MEMS(Micro-Electro mechanical system) to match the impedances to realize the bands of interest. Because the two proposed antennas are polarized orthogonally to each other, the ECC(Envelope Correlation Coefficient) characteristic between two antennas was measured to be very low (below 0.06) with an isolation characteristic below -20 dB between the two antennas in the operating overall LTE bands. The proposed antenna is particularly attractive for mobile devices that integrate LTE multiple systems.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.60-68
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• 2001

본 논문에서는 최근 초소형 기술로 각광받고 있는 MEMS(MicroElectroMechanical System) 기술을 이용한 무선통신 분야의 응용을 제고한다. RF ME- MS 기술은 기존의 기술들에 비해 크기나 전력소모, 삽입손실 등에서 우수한 고주파 특성을 갖는 소자 나 부품을 만들 수 있으며 특히 휴대용 단말기에 적 용 가능한 RE 부품들 즉 저손실 전송선로, 스위치, High Q inductor, 안테나 등의 주요 부품에 대한 연 구가 많이 이루어지고 있다.

• Journal of Sensor Science and Technology
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• v.14 no.1
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• pp.16-21
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• 2005

This paper presents the development of the optical switch using magnetic behavior of magnetic fluids, which is expected to be used broadly in high-speed information communication. The magnetic fluids for switching an incident light, have the magnetic characteristics of magnetic materials and fluidity of liquids, simultaneously. The relations are derived between the intensity of magnetic field and the angle of optical fiber which is bent by a behavior of magnetic fluid when the magnetic field is applied. When optical switch is implemented by the movement of liquid using magnetic fluid, the existing problem of durability for optical switch will be improved. Thus, this study shows the feasibility of the application for the optical switches using magnetic fluids.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.258-259
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• 2002

광회선 분배 시스템(OXC)은 전광통신망(Optical Transport Network)에서 광신호 간 연결을 원격으로 설정해 줄 수 있는 노드(Optical Network Element)이다. OXC는 다수의 입력/출력 링크를 가지며 하나의 입력/출력 링크에는 다수의 파장 다중된 광신호 채널이 존재한다. OXC는 하나의 입력 링크를 통하여 입력되는 다수의 파장 채널을 서로 다른 출력 링크로 연결해 주거나, 다수의 입력 링크로부터 입력되는 파장채널을 하나의 출력 링크로 연곁해 줄 수 있는 optical grooming 기능을 수행한다. 또한 자국에서 광신호를 Add/Drop할 수 있는 기능을 가질 수 있다. (중략)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1255-1260
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• 2003

In order to reduce driving power consumption, we propose and fabricate a new structure of asymmetric SOI 1${\times}$2 thermo-optic switch that has a back side silicon trenched structure. Compared to conventional SOI thermo optic switches without heat sink structure, it shows an improvement of switching power reduction from about 4 watt to 1.8 watt without sacrificing cross talk of about 20 ㏈ at the light wavelength of 1.55 $\mu\textrm{m}$. Here we also described the main design consideration and fabrication procedure for the proposed device.

• Laser Solutions
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• v.3 no.3
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• pp.21-29
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• 2000

For the direct metal shape processing the powder feed device which is different from the widely used in rapid prototyping. is developed, The three dimensional object is shaped with the melting metal powder. The developed research has applied to rapid prototyping in ultraprecision for MEMS and medical science fields required of rapid manufacture of complex shape. The goal of this study make 3D model which has precision accuracy. Powder spreading apparatus has been more improved because that the control of powder spread is very important in layer manufacturing. It consists of the vibration motor, nozzle and tube which supplies various metal powder. This apparatus could control the spreading velocity that could control powder spreading thickness. Laser on/off switch was adapted because laser scanning velocity must be preserved constantly to prevent heat transformation of laser overheating. The error between sintered thickness md experimental one occurred by shrinkage in sintering melting process. The problem of heat transformation was solved by On/Off switching system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.9
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• pp.546-551
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• 2000

A micromechanical switch that can be used as a logic gate is described in this paper. This switch consists of fixed input electrodes an output electrode Vcc/GND electrodes and movable plates suspended by crab-leg flexures. for mechanical switching of an electrical signal a parallel plate actuator which comes in contact with output electrode was used. Provided that movable plates are connected to Vcc and a low input voltage(ground signal) is applied to the fixed input electrodes the movable plates are pulled by an electrostatic force between the fixed input electrodes and the movable plates. the proposed micromechanical switch was fabricated by surface micromachining technology with$2\mum$ -thick poly-Si and the measured threshold voltage for ON/OFF switching was 23.5V.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.467-468
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• 2006

In this work, we present the comparison between $d_{31}\;and\;d_{33}$ mode characterization using the PZT micro-actuator for large displacement. The PZT micro-actuator consisted of Si, PZT, and Pt layer on SOI wafer. The electrode shapes were laminated and interdigitated for $d_{31}\;and\;d_{33}$ mode, respectively. In order to characterize the actuation mode, we measured the displacement using laser interferometer. The maximum displacement of d31 mode was $12.2{\mu}m$ at 10V, the actuation characterization of d31 was better than that of d33 mode. We estimated that displacement of d33 mode would be larger than that of d31 above 30V.