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Optics-based Wireless Sensor Node Localization using MEMS CCR
전현철,박찬국,전지헌 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.6
In this paper, we analyze the phenomena and problems that can occur in the sensor node localization of optics-based sensor networks using MEMS (Micro Electro Mechanical Systems) CCR (Corner Cube Retro-reflector). CCR reflects incident rays back in the opposite direction to calculate the distance between the sensor node and the base station and measuring the difference in source and sink detection time. The sensor node position can be measured from the ToF (Time of Flight) and the AoA (Angle of Arrival). However, when the MEMS CCR is used, reflected ray’s power is not strong enough to be detected. In the optics-based sensor network, sensor nodes are distributed randomly. Some sensor nodes cannot be detected due to the rectilinear propagation characteristics of light. To overcome these problems, we analyze the reflected ray’s power and verify the results experimentally. Based on the analysis, we replaced the photo detector to increase the detectable range. We also showed that multiple base stations can solve the randomly distributed sensor node issue and improve sensor node localization.
Sn-1.7Bi-0.7Cu-0.6In 솔더의 특성 연구
박지호,이희열,전지헌,전주선,정재필,Park, Ji-Ho,Lee, Hee-Yul,Jhun, Ji-Heon,Cheon, Chu-Seon,Jung, Jae-Pil 대한용접접합학회 2008 대한용접·접합학회지 Vol.26 No.5
Characteristics of Sn-1.7%Bi-0.7%Cu-0.6%In (hereafter, SBIC) lead-free solder was investigated in this study. The results from SBIC were compared to other lead-free solders such as Sn-3.5%Ag-0.7%Cu (hereafter, SAC), Sn-0.7%Cu (hereafter, SC), and lead-bearing Sn-37%Pb (hereafter, SP) alloy. Tensile properties of bulk solder, wettability, spreading index, bridge and dross were evaluated. As experimental results, tensile strength and elongation of SBIC was 62.5MPa and 21.5%, respectively. The tensile strength was comparable to that of SP solder. The wetting time of SBIC was 1.2 sec at $250^{\circ}C$, and its wetting properties including wetting force were as good as the SAC alloy. However, wettability of the SC was not so good as the SBIC and SAC. The spreading index of SBIC at $250^{\circ}C$ was 71 %, and it was similar level to those of SAC and SC solders. Bridging was not found for all solders of SBIC, SAC and SC in the range from 240 to $260^{\circ}C$. In dross test at $250^{\circ}C$ for an hour, the amount of dross produced from SBIC was about 57% compared to that from SAC.
전해도금을 이용한 straight wall형 Sn-Cu 초미세 솔더 범프 형성
이기주,김규석,홍성준,이희열,전지헌,김인희,정재필 한국표면공학회 2007 한국표면공학회 학술발표회 초록집 Vol.2007 No.-
본 연구에서는 범프를 형성하는 여러 가지 방법중 전해도금을 이용하여 Sn-Cu 솔더 범프를 형성하고자 하였다. 기초적인 도금 특성을 알아보기 위하여 전류밀도 에 따른 증착속도, 도금 시간에 따른 도금두께 등을 측정 하였으며, 최종적으로는 20×20×10㎛ 크기에 50㎛ 피치를 갖는 Sn-Cu 솔더 범프를 형성하고자 하였다.