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Clarke & Gans 페이딩 채널 환경에서 무선 LAN용 OFDM 시스템의 성능 분석
염우섭(Wu-Seob Yeom),강희조(Heau-Jo Kang),김윤호(Yoon-Ho Kim) 한국정보기술학회 2007 Proceedings of KIIT Conference Vol.2007 No.-
OFDM(orthogonal frequency division multiplexing) 방식은 보호구간의 삽입을 통하여 lSI를 방지할 수 있으므로 고속 데이터 전송에 적합하다. 따라서, 본 논문에서는 데이터 변조 방식으로는 IEEE 802.11a에 근거한 부반송파의 수가 64개인 QPSK변조 방식을 사용하는 OFDM 시스템을 모델링 하고, 도플러 천이 효과를 고려한 Clark & Gans 페이딩 환경에서 성능을 분석하였다. 또한 채널 상태에 대한 추정기능을 이용하여 충분히 큰 전력을 갖는 다중 경로파만을 보상하는 것에 의해 연산량을 증대시키는 것 없이 지연시간이 큰 다중 경로파를 보상하는 적응형 등화기를 이용한다.
AFM 을 위한 VCM 구동 flexure hinge 스테이지의 최적 설계 및 제어
염우섭(WooSub Youm),이성규(Sung-Q Lee),박기환(KyiHwan Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
A systemic design procedure of general VCM (Voice Coil Motor) to fine z-axis AFM (Atomic Force Microscopy) actuator is introduced for fast and precision actuation. As a fine z-axis actuator, PZT and flexure hinge mechanism has been widely used for AFMs. However, PZT actuator has disadvantages of hysteresis, creep, and short working distance. Therefore, in this research, the VCM and flexure hinge mechanism is selected to be free from the weakness of the PZT actuator. In design procedure, design parameters are selected based on the dynamic model of VCM and flexure hinge, and design process is proceed in point of fast and precision actuation. To verify the performance of the designed actuator, frequency response of the actuator and contact type AFM image of standard grid sample are performed.
염우섭(WooSub Youm),황건(Gunn Hwang),이성규(Sung Q Lee) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.4
Recently, wireless power transfer technology is ready to be commercialized in consumer electronics. It draws attention of not only experts but also public because of its convenience and huge market. However, previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic intensity limitation for the safety of body exposure. As an alternative, ultrasonic wireless power transfer technology is proposed. The ultrasonic wireless power transfer system is composed of transmitter which converts electrical energy to ultrasonic energy and receiver which converts the ultrasonic energy to the electrical energy again. This paper is focused on the development of high energy conversion efficiency of ultrasonic transmitter. Optimal transfer frequency is calculated based on the acoustic radiation and damping effect. The transmitter is designed through numerical analysis, and is manufactured to match the optimal transfer frequency with the size of 100mm diameter, 12.2 mm thickness plate. The energy conversion efficiency of about 13.6% at 2m distance is obtained, experimentally. This result is quite high considered with the device size and the power transfer distance.
무선 전력전송을 위한 초음파 트랜스듀서 시스템 개발 Part 1
염우섭(Youm, Woo-Sub),황건(Hwang, Gunn),양우석(Yang, Woo-Seok),이성규(Lee, Sung-Q) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.9
Recently, wireless power transfer technology is ready to be commercialized in consumer electronics. It draws attention from not only experts but also public because of its convenience and huge market. However, previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic intensity limitation on the safety of body exposure. As an alternative, ultrasonic wireless power transfer technology is proposed. The ultrasonic wireless power transfer system is composed of transmitter which converts electrical energy to ultrasonic energy and receiver which converts the ultrasonic energy to the electrical energy again. This paper is focused on the development of high energy conversion efficiency of ultrasonic transmitter. Optimal transfer frequency is calculated based on the acoustic radiation and damping effect. The transmitter is designed through numerical analysis, and is manufactured to match the optimal transfer frequency with the size of 100 mm diameter, 12.2 mm thickness plate. The energy conversion efficiency of about 13.6 % at 2 m distance is obtained, experimentally. This result is quite high considered with the device size and the power transfering distance.
이성규,염우섭,황건,Lee, S.Q.,Youm, W.S.,Hwang, G. 한국전자통신연구원 2013 전자통신동향분석 Vol.28 No.5
인구 고령화와 복지증진에 따라 인체 삽입형 의료기기에 대한 연구가 활발히 진행되고 있으며, 더 다양한 기능을 제공하는 제품들이 출시되고 있다. 반면, 이러한 다양한 기능의 요구로 인해 인체 삽입형 의료기기의 전력소모가 커지고 있어 일차전지만으로는 충분한 기능을 제공하지 못하거나 한정된 사용시간으로 말미암아 환자들이 삽입형 의료기기의 전원공급만을 위해서 추가적인 비용과 고통을 감수하고 있는 현실이다. 본고에서는 무선 전력 전송 기술을 활용하여 인체 삽입용 의료기기로 전력을 무선으로 전송하고 재충전이 가능한 인체 삽입용 의료기기의 기능과 사용 시간의 확대를 가능하게 하는 무선 충전 전원 모듈 기술의 동향과 전망을 살펴봄으로써 관련 국내 산업계가 기술 전환기를 대비하는데 필요한 기초 정보를 제공하고자 한다.
스마트 IT 융합 플랫폼을 위한 지능형 센서 기술 동향
김혜진,진한빛,염우섭,김이경,박강호,Kim, H.J.,Jin, H.B.,Youm, W.S.,Kim, Y.G.,Park, K.H. 한국전자통신연구원 2019 전자통신동향분석 Vol.34 No.5
As the Internet of Things, artificial intelligence and big data have received a lot of attention as key growth engines in the era of the fourth industrial revolution, data acquisition and utilization in mobile, automotive, robotics, manufacturing, agriculture, health care and national defense are becoming more important. Due to numerous data-based industrial changes, demand for sensor technologies is exploding, especially for intelligent sensor technologies that combine control, judgement, storage and communication functions with the sensors's own functions. Intelligent sensor technology can be defined as a convergence component technology that combines intelligent sensor units, intelligent algorithms, modules with signal processing circuits, and integrated plaform technologies. Intelligent sensor technology, which can be applied to variety of smart IT convergence services such as smart devices, smart homes, smart cars, smart factory, smart cities, and others, is evolving towards intelligent and convergence technologies that produce new high-value information through recognition, reasoning, and judgement based on artificial intelligence. As a result, development of intelligent sensor units is accelerating with strategies for miniaturization, low-power consumption and convergence, new form factor such as flexible and stretchable form, and integration of high-resolution sensor arrays. In the future, these intelligent sensor technologies will lead explosive sensor industries in the era of data-based artificial intelligence and will greatly contribute to enhancing nation's competitiveness in the global sensor market. In this report, we analyze and summarize the recent trends in intelligent sensor technologies, especially those for four core technologies.
VCM(voice coil motor)를 이용한 3차원 나노 형상 측정 시스템
정종규(Jongkyu Jung),염우섭(Woosub Youm),박기환(Kiyhwan Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
In this paper, vibration reduction techniques of a voice coil motor (VCM) actuator are presented for AFM imaging system. The damping coefficient of the actuator driven by VCM with a flexure hinge is quite low and it cause the about 30㏈ peak amplitude response at the resonance frequency. To decrease this peak response, we design and apply elliptical band-stop filters to xy and z axis VCM actuator. Frequency response of each actuator with filter is measured to verify the effect of the filters. As a sensor, capacitive sensor is used. Vibration reduction rate of the xy actuator with the filter is also measured while real AFM scanning condition. As another method, closed loop control with the capacitive sensor is applied to the xy axis actuator to add an electrical damping effect and vibration reduction rate measured. These vibration reduction rates with each method are compared. In the case of z axis actuator, the frequency response of force (gap) control loop is measured. For comparison, the frequency response using a conventional PID controller is also obtained. Finally, the AFM image of a standard grid sample is measured with the designed controller to analyze the effect in the AFM imaging.