• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.9-17
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• 2018

For Earth observation, a small satellite camera has relatively weak structural stability compared to medium-sized satellite, resulting in misalignment of optical components due to severe launching and space environments. These alignment errors can deteriorate the optical performance of satellite cameras. In this study, we proposed a 3-axis focus mechanism to compensate misalignment in a small satellite camera. This mechanism consists of three piezo-electric actuators to perform x-axis and y-axis tilt with de-space compensation. Design requirements for the focus mechanism were derived from the design of the Schmidt-Cassegrain target optical system. To compensate the misalignment of the secondary mirror (M2), the focus mechanism was installed just behind the M2 to control the 3-axis movement of M2. In this case, flexure design with Box-Behnken test plan was used to minimize optical degradation due to wave front error. The wave front error was analyzed using ANSYS. The fabricated focus mechanism demonstrated excellent servo performance in experiments with PID servo control.

• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.26-36
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• 2019

The precise alignment between optical components is required in high-resolution earth observation satellites. However, the misalignment of optical components occurs due to external factors such as severe satellite launch environment and space environment. A satellite optical system with a focus mechanism is required to compensate for the image quality degraded by these misalignments. This study designed, fabricated, aligned precisely, and carried out a performance tests for the image quality of the system. The satellite optical camera performance tests were carried out to check the image quality change by operating the focus mechanism and to analyze the satellite optical system MTF by photographing USAF target using the autocollimator. According to the experimental results, the misalignments can be compensated sufficiently with the focus mechanism. Finally the basic data for re-focusing algorithm of the optical system was obtained through this study.

• The Journal of the Korea Contents Association
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• v.19 no.1
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• pp.445-462
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• 2019

This paper illustrated the use of focus groups with adolescents and youth experts to enhance knowledge of anger, anger expression, and its coping strategies. Nine youth experts and 9 adolescents participated in the study. Analysis of the findings identified 12 meaningful elements, 34 sub-elements, and 138 descriptions. The meaningful elements were as follow: the lack of stable care, anger-provoking situations, a relationship between distorted thoughts and anger, physical and psychological symptoms, different types of anger expression, suppressed anger, difficulty of anger control, youth efforts to control anger, needs to implement appropriate anger expression, psychological mechanism of anger, effective ways to cope with anger, suggested by youth experts, needs of alternative anger management programs. Based on these findings, the study suggests various anger management alternatives, including ICT based cognitive-behavior anger management programs.