• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.82-89
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• 2020

Among the explosives in ammunition, the delay elements, which are used as a retardant, could be influenced by the ambient temperature in the Republic of Korea, where the highest and lowest average annual temperature difference is clear. On the other hand, there has been no domestic research on this. This study examined the linear burning rates of the zirconium-nickel delay elements depending on the ambient temperature in South Korea. The ambient temperature data of South Korea were obtained from the meteorological administration, which was used to set the experimental conditions. The operational time for the K414 fuze was measured by changing the ambient temperature by 10 ℃ from -40 ℃ to 50 ℃. To convert the delay time into the burning rates, the height of the delay element in the K414 fuze body was used. The results indicated that the characteristics of the burning rates for the zirconium-nickel delay element could be estimated as linear, and both the burning rates and the delay time of the zirconium-nickel delay element were 2.73mm/ms and -4.18ms, respectively. This led to an approximately 80 ms delay time difference in the environment where the highest and lowest average annual temperature difference was above 20 ℃. Therefore, the delay time reflecting the ambient temperature should be considered when the test evaluation criteria of zirconium-nickel delay elements are established.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.291-300
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• 2020

The cartridges used for illuminating a desired point or area are virtually limited in tests and evaluations because of limitations, such as noise during launch, the possibility of fires caused by illuminant charge, and the annual testable quantity. Therefore, to solve these problems, a ground fixed test, which replaces the firing test, or an evaluation method to perform limited tests, can be applied more efficiently. In this paper, the results of an 81mm illuminating cartridge, KM series performed in 2019 were analyzed comprehensively to identify the trends in reliability and quality characteristics and to estimate the shelf life. The shelf life was estimated to be at least 10 years based on the time when the lower confidence level reached 80% at a confidence level of 90%. Considering only major defects, the shelf life can be estimated to be approximately 23 years. On the other hand, the shelf life was estimated to be approximately 11 to 15 years and 25 to 28 years according to the effective illuminating time. Finally, an assessment plan of illuminating cartridges for the mortars was also presented as an improvement plan for an assessment method in the future.