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정원규(Won-Kyu Jeung),최석문(Seog-Moon Choi),김용준(Yong-Jun Kim) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
A new thermal bimorph actuator for large out-of-plane displacement is designed, fabricated and tested. The deflecting beam is composed of polyimide, heater, and polyvinyl difluorides with tetrafluoroethylene(PVDF-TrFE). The large difference of coefficient of thermal expansion(CTE) of two polymer layers (polyimide and PVDF-TrFE) can generate a large deflection with relatively small temperature rising. Compared to the most conventional micro actuators based on MEMS(micro-electro mechanical system) technology, a large displacement, over 1 mm at 20 mW, could be achieved. The proposed actuator can find applications where a large vertical displacement is needed while keeping compact overall device size, such as a micro zooming lens.
IC-임베디드 PCB 공정을 사용한 DVB-T/H SiP 설계
이태헌(Tae-Heon Lee),이장훈(Jang-Hoon Lee),윤영민(Young-Min Yoon),최석문(Seog-Moon Choi),김창균(ChangGyun Kim),송인채(In-Chae Song),김부균(Boo-Gyoun Kim),위재경(Jae-Kyung Wee) 大韓電子工學會 2010 電子工學會論文誌-SD (Semiconductor and devices) Vol.47 No.9
본 논문에서는 유럽에서 사용되는 이동형 디지털 방송인 DVB-T/H 신호를 수신 및 신호처리 가능한 DVB-T/H SiP를 제작하였다. DVB-T/H SiP는 칩이 PCB 내부에 삽입될 수 있는 IC-임베디드 PCB 공정을 적용하여 설계되었다. DVB-T/H SiP 에 삽입된 DVB-T/H IC는 신호를 수신하는 RF 칩과 어플리케이션 프로세서에서 활용할 수 있도록 수신된 신호를 변환하는 디지털 칩 2개를 원칩화한 모바일 TV용 SoC 이다. SiP 에는 DVB-T/H IC를 동작하기 위해 클럭소스로써 38.4㎒의 크리스탈을 이용하고, 전원공급을 위해 3㎒로 동작하는 DC-DC Converter와 LDO를 사용하였다. 제작된 DVB-T/H SiP는 8㎜ × 8㎜ 의 4 Layer로 구성되었으며, IC-임베디드 PCB 기술을 사용하여 DVB-T/H IC는 2층과 3층에 배치시켰다. 시뮬레이션결과 Ground Plane과 비아의 확보로 RF 신호선의 감도가 개선되었으며 SiP로 제작하는 경우에 Power 전달선에 존재하는 캐패시터와 인덕터의 조정이 필수적임을 확인하였다. 제작된 DVB-T/H SiP의 전력 소모는 평균 297㎽이며 전력 효율은 87%로써 기존 모듈과 동등한 수준으로 구현되었고, 크기는 기존 모듈과 비교하여 70% 이상 감소하였다. 그러나 기존 모듈 대비평균 3.8㏈의 수신 감도 하락이 나타났다. 이는 SiP에 존재하는 DC-DC Converter의 노이즈로 인한 2.8dB의 신호 감도 저하에 기인한 것이다. This paper reports the fabrication of a DVB-T/H System in Package (SiP) that is able to receive and process the DVB-T/H signal. The DVB-T/H is the European telecommunication standard for Digital Video Broadcasting (DVB). An IC-embedded Printed Circuit Board (PCB) process, interpose a chip between PCB layers, has applied to the DVB-T/H SiP. The chip inserted in DVB-T/H SiP is the System on Chip (SoC) for mobile TV. It is comprised of a RF block for DVB-T/H RF signal and a digital block to convert received signal to digital signal for an application processor. To operate the DVB-T/H IC, a 3㎒ DC-DC converter and LDO are on the DVB-T/H SiP. And a 38.4㎒ crystal is used as a clock source. The fabricated DVB-T/H SiP form 4 layers which size is 8㎜ × 8㎜. The DVB-T/H IC is located between 2nd and 3rd layer. According to the result of simulation, the RF signal sensitivity is improved since the layout modification of the ground plane and via. And we confirmed the adjustment of LC value on power transmission is necessary to turn down the noise level in a SiP. Although the size of a DVB-T/H SiP is decreased over 70% than reference module, the power consumption and efficiency is on a par with reference module. The average power consumption is 297㎽ and the efficiency is 87%. But, the RF signal sensitivity is declined by average 3.8㏈. This is caused by the decrease of the RF signal sensitivity which is 2.8㏈, because of the noise from the DC-DC converter.
최석문,이상조,윤영식 연세대학교 산업기술연구소 1991 논문집 Vol.23 No.2
The cutting amount of each tooth in gear hobbing has much influence on the vibration of the hob axis and the wear of tool. In this study, with the simulation of gear hobbing mechanism, cutting parameters such as cutting thickness, cutting are and area moment were calculated. The cutting torque was also obtained by the experiments. The cutting amount of each tooth in the hob can be compared quantitatively by the simulation on the calculated cutting zone, cutting thickness and cutting are. And the cutting torque obtained by the experiments has the same tendency with the area moment calculated by the simulations. The results of this study can be applied to the research on the tool wear, the hob having modified tooth profile and the variation of cutting torque.