Earticle

Demand for high power motors is rapidly increasing as the 4th industry and convergence technology has recently emerged. In order to produce high-strength permanent magnets, the magnets used for magnetization have been increased from DC 300V in the 1970s to DC 2.5kV in the 2010s, Up to DC 10kV in the 2030s, It is expected that higher voltage will be used to magnetize. However, in the case of a magnetizer using an existing electric signal control device, it is necessary to use a control device with a high-voltage insulation function in case a high voltage used for magnetization is leaked to the control device. If a short circuit accident occurs, the controller must be shut down and serious problems such as excessive repair costs arise. In this study, a control system adopting optical communication method instead of electric signal control method is proposed to prevent leakage currents in high-voltage magnetizer. We design a transmitter(Tx) and a receiver(Rx) device for the optical communication control device and implemented a prototype connecting the optical cable. In order to demonstrate the utility of high-voltage magnetizer using the optical communication control device, we analyzed the initial cost and the yearly cost for the years to analyze the net present value. As a result, In the case of the low-voltage magnetizer, the electric signal control method cost less, As the operating voltage of the magnetizer becomes higher. It is confirmed that it takes less cost when the optical communication control device is used.

In this paper, we proposed a new dimming control scheme by using direct sequence spreading coding (DSSC) scheme in visible light communication (VLC). VLC systems using LED lighting can provide illumination functions and communication services at the same time. In order to provide simultaneous illumination and communication services, dimming control should be considered. Dimming control means that LED lighting should maintain a constant brightness in accordance with user requirements while communication services are offered. In IEEE 802.15.7 VLC standard, on-off keying (OOK) and variable pulse position modulation (VPPM) are defined as pulse modulation schemes for dimming control. In particular, 4B/6B, 8B/10B block coding and Manchester coding schemes have been proposed for stable dimming control in OOK. However, in such a case, stable dimming control is possible although the communication performance is degraded. In order to solve those problems, we propose a VLC system based on OOK modulation with DSSC. The proposed system can simultaneously stabilize dimming control and improve communication performance by obtaining spread diversity gain. The simulation results show that the proposed system provides superior dimming and BER performances compared to conventional dimming modulation schemes.

Demand for high power motors is rapidly increasing as the 4th industry and convergence technology has recently emerged. In order to produce high-strength permanent magnets, the magnets used for magnetization have been increased from DC 300V in the 1970s to DC 2.5kV in the 2010s, Up to DC 10kV in the 2030s, It is expected that higher voltage will be used to magnetize. However, in the case of a magnetizer using an existing electric signal control device, it is necessary to use a control device with a high-voltage insulation function in case a high voltage used for magnetization is leaked to the control device. If a short circuit accident occurs, the controller must be shut down and serious problems such as excessive repair costs arise. In this study, a control system adopting optical communication method instead of electric signal control method is proposed to prevent leakage currents in high-voltage magnetizer. We design a transmitter(Tx) and a receiver(Rx) device for the optical communication control device and implemented a prototype connecting the optical cable. In order to demonstrate the utility of high-voltage magnetizer using the optical communication control device, we analyzed the initial cost and the yearly cost for the years to analyze the net present value. As a result, In the case of the low-voltage magnetizer, the electric signal control method cost less, As the operating voltage of the magnetizer becomes higher. It is confirmed that it takes less cost when the optical communication control device is used.

Free-space optical communication technology enables the high-speed data transmission and excellent anti-jamming security. We conduct research on satellite-to-ground free-space optical communication links for high-speed transmission of large-capacity surveillance and reconnaissance data. Since the satellite continues to move along its orbit while the optical signal is transmitted between the satellite and the ground, the pointing angle of the beam from the ground terminal needs to be corrected by Point Ahead Angle(PAA) so that the transmitted light reaches the expected location of the satellite. In this paper, we present the algorithm for PAA estimation and control.

본 논문에서는 위험요소를 내재하고 있는 로켓시스템에 대해 원거리에서 실시간 모니터링 및 제어를 할 수 있도록 원격 제어시스템을 설계, 개발하였다. 뿐만 아니라 로켓 근처에 위치한 무인 시설물 내에는 원격제어에 따른 로켓내부 시스템의 각종 센서 출력값을 멀티채널방식을 이용하여 장시간에 걸쳐 저장하고 원격지에 위치한 유인 시설물 내에서 LAN 통신을 통해 데이터를 분석할 수 있도록 DAS(Data Acquisition System)을 설계하고 개발하였다. 개발된 시스템은 간이 연계시험을 통해 입증하였으며, 향후 3단형 과학로켓발사통제시스템에 적용할 예정이다.