• 대한수학교육학회지:수학교육학연구
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• 제12권4호
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• pp.457-472
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• 2002

In this paper, we deal with the algebraic thinking from the perspective of ‘process’ and ‘object’ aspects. Generally, mathematical concepts have come from the concrete process. We consider the origin of algebra as the arithmetic calculations. Also, the concept of school arithmetic is beginning from actions or procedures. However, in order to develop the alge- braic thinking and to apply this thinking, we have to see the history of algebraic thinking, and find this duality. Next we investigate various researches relating to the ‘process-object duality’. Theses studies suppose that the concept formation and thinking process should be stared from the process-object duality. Finally, we reinterprete many difficulties in algebra - equals sign, variables, algebraic expressions, and linear equations, the principle of permanence of form- from the perspective of the process-object duality.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권2호
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• pp.97-102
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• 2014

Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects. High power amplifier Module is the most critical part of the high-power radar transmitter systems. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. Research related to radar has been conducted in various fields according to improvement of the communication technology. But only performance-originated technology development has been dashed; study concerning environment duality and safety concerning reliability are still insufficient. In general, radar module is exposed to the outside, on the means of moving or fixed in a certain place. It should be guaranteed sufficient immunity for a variety of environmental stresses that can occur in the outdoor. HALT is a great process used for quickly finding failure mechanisms in a hardware design and product. By applying various kinds and extreme level of stresses, we can find the operating limits of products. In thesis, we conducted HALT test of the high power amplifier modules which used in military and automotive radar. After the test, we analyzed environmental weaknesses of high power amplifier modules using conventional construction data.