• Journal of the Korean Society of Systems Engineering
• /
• v.19 no.1
• /
• pp.29-38
• /
• 2023

Independent Safety Assessment (ISA) is a third-party assessment that is to confirm that the system satisfies the safety requirements in the defined operational context. The process of this assessment often brings about many complex arguments that should be supported by evidence and justification. The communication between arguments and evidence is of the most importance in the context of safety case. This study illustrates how NOR-STA can be used for ISA process, showing the effective structure of safety compliance. The study outlines the steps to breaks down the top goal into many elements such as arguments, sub-goals, justification, context and assumptions. It concludes that the evidence-based safety conformance process utilizing NOR-STA provides a more effective and systematic representation of the independent safety assessment process in conformance cases.

• Korean Journal of Weed Science
• /
• v.2 no.1
• /
• pp.7-12
• /
• 1982

The experiment was studied to know the competitive ability of rice against weeds as affected by rice maturity and plant spacing. For both cultivars, Tongil (12 days later) and Yeongnamjosaeng, the least amount of weed was obtained from the 10 ${\times}$ 10cm plant spacing while no difference between 40 ${\times}$ (10 ${\times}$ 10cm) and 30 ${\times}$ 15cm plant spacings was observed. When weed was nor pulled out by hand, significant yield loss was resulted in 30 ${\times}$ 15cm and 40 ${\times}$ (10 ${\times}$ 10cm) plant spacings while no difference between weeding regime was observed at the 10 ${\times}$ 10cm plant spacing in both cultivars. Rice grain yield was unaffected by plant spacing for hand weeded plot in both rice cultivars. For noweeding plot, however, the highest grain yield was obtained from 10 ${\times}$10cm plant spacing and also this yield was not significantly different from the yield of hand weeded plot while significant yield loss was recognized at the 30 ${\times}$ 15cm and 40 ${\times}$ (10 ${\times}$ 10cm) plant spacings in noweeding plot. There was also a good relationship between weed weight and grain yield for both cultivars (Tongil; Y = 5.68 - 0.0127 X, r = -0.814$^*$; Yeongnamjosaengv Y = 5.04 - 0.0314 X, r =-0.9704$^{**}$). Based on these relationship, weed weight of 188.2g/sq.m for Yeongnamjosaeng and 223.6g/sq.m for Tongil was needed to reduce rice yield by 50%, respectively. This result implied that Tongil compete more efficiently against weed than Yeongnamjosaeng and hence, could be concluded that late maturing cultivar was more competitive against weed compared to early maturing cultivar.