• Korean Journal of Environment and Ecology
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• v.36 no.5
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• pp.535-549
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• 2022

Damage to forests, such as broken or falling trees, has increased due to the increased intensity and frequency of abnormal climate events, such as strong winds and heavy rains. However, it is difficult to respond to them in advance based on prediction since structural defects such as cavities and bumps inside trees are difficult to identify with a visual inspection. Non-invasive sonic tomography (SoT) is a method of estimating internal defects while minimizing physical damage to trees. Although SoT is effective in diagnosing internal defects, its accuracy varies depending on the species. Therefore, it is necessary to analyze the reliability of its measurement results before applying it in the field. In this study, we measured internal defects in wood by cross-applying destructive resistance micro drilling on old Pinus densifloraSiebold & Zucc. and Ginkgo bilobaL., which are representative tree species in Korea, to verify the reliability of SoT and compared the evaluation results. The t-test for the mean values of the defect measurement between the two groups showed no statistically significant difference in pine trees and some difference in ginkgo trees. Linear regression analysis results showed a positive correlation with an increase in defects in SoT images when the defects in the drill resistance graph increased in both species.

• Clinical and Experimental Pediatrics
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• v.48 no.7
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• pp.706-710
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• 2005

Purpose : Early diagnosis of congenital hearing loss through the neonatal hearing screening test minimizes language defect. This research intends to identify frequency of congenital hearing loss in infants through neonatal hearing screening test with the aim of communicating the importance of hearing test for infants. Methods : From May 20, 2003 to May 19, 2004, infants were subjected to Automated Auditory Brainstem Response test during one month of birth to conduct the test with 35 dB sound. Infants who passed the 1st round of hearing test, were classified into 'pass' group whereas those who did not were classified into 'refer' group. Infants who did not 'pass' in the hearing test conducted within one month of birth were subjected to re-test one month later, and if classified as 'refer' during the re-test, they were subjected to the diagnosis for validation of hearing loss by requesting test to the hearing loss clinic. Results : There was no difference among the 'pass' and 'refer' group in terms of form of childbirth, weight at birth and gestational age. In the 1st test, total of 45 infants were classified into 'refer' group. Six among 35 who were subjected to re-test(17%) did not pass the re-test, and all were diagnosed with congenital hearing loss. This corresponds to 0.35%(3.5 per 1,000) among total number of 1,718 subjects. Conclusion : In our study the congenital hearing loss tends to be considerably more frequently than congenital metabolic disorder. Accordingly, newly born infants are strongly recommended to undergo neonatal hearing screening test.