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박지인,이경수 대한기계학회 2007 環境管理學會誌 Vol.2007 No.5
This paper describes a robust model-based roll state estimator for application to the detection of impending vehicle rollover. The roll state estimator is based on a 2-D bicycle model and a roll model to estimate the maneuver-induced vehicle roll motion. The measurement signals are lateral acceleration, yaw rate, steering angle, and vehicle speed. Vehicle mass is adapted to obtain robust performance of the estimator. Computer simulation is conducted to evaluate the proposed roll state estimator by using a validated vehicle simulator. It is shown that the roll state estimator shows robust performance without exact vehicle mass information.
Characterization of CdS Photocells for Portable X-ray Dosimeters
박지군,강상식,최일홍,노시철,김현희,최흥호,남상희 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61
Given the importance of radiation monitoring, the development of portable dosimetry systems is of particular interest in a wide range of medical and industrial applications. Compared with bulky Geiger-M?ler-type proportional counters, semiconductor-based radiation detectors, particularly those using compound semiconductors, have drawn considerable recent interest due to their scope for miniaturization. CdS is a highly sensitive II-VI compound semiconductor whose internal resistance changes on exposure to X-rays and is capable of absorbing green light in the range of 2.5 - 3.5 eV (490 - 511 nm). Despite its slow response compared with amorphous selenium, it has several advantages for digital radiography because of its low voltage requirements, high X-ray sensitivity, and high absorption coefficient. In this study, the X-ray detection characteristics of a CdS photocell were evaluated for use in an economical, portable X-ray dosimeter. A CdS photocell with a thickness of 20 탆 was fabricated by using thermal evaporation, and the ratio of its photocurrent to its dark current was found to be on the order of 105 with a maximum allowed power consumption of over 80 mW. The cell was incorporated into a prototype X-ray dosimeter system with an 8051 microprocessor, used to measure the output voltage characteristics of the CdS cell for various tube voltages, tube currents, and exposure times. The experimental results confirmed good linearity with tube voltage and current, but a delayed response. The results of this study can be used as the basis for the design of accurate, economical, and portable X-ray dosimeters.