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Korea Forest Service has supplied 76 industrial wood pellet boilers from 2011 to 2015 through subsidy programs. Since carbon monoxide (CO) and nitrogen oxides (NOx) generated during boiler combustion are substances that lead to death in the case of acute poisoning, it is very important to reduce emissions. Therefore, the CO and NOx emission values of 63 boilers excluding the hot air blower and some boilers initially supplied were analyzed. The emission factor was also calculated from the measured exhaust gas concentration (based on exhaust gas O2 concentration of 12%). The average value of CO emitted from industrial wood pellet boilers was 49 ppm and it was confirmed that the CO concentration was decreasing as the years passed. The emission factor of CO was 0.73 g/kg. The average value of NOx emitted from industrial wood pellet boilers was 67 ppm and the emission factor of NOx was 1.63 g/kg. Unlike CO, there was no tendency to decrease according to the installation year. Both CO and NOx measurements met the limits of the Ministry of Environment. These NOx emission factors were compared with the NOx emission factors produced by certified low NOx burners. The NOx emission factor of industrial wood pellet boilers was about 1.9 times that of certified low NOx LNG combustors and about 0.92 times that of coal combustion.

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Background and Objectives Cochlear dead region (CDR) is a region in the cochlear where hearing loss has occurred due to damage to the inner hair cells and/or neurons. Recently, a subjective test involving a pure-tone test in the presence of threshold-equalizing noise (TEN) was introduced to identify CDR. However, for uncooperative patients, such a subjective method would be unsuitable and objective methods would be needed instead to detect CDR. The acoustic change complex (ACC) is an evoked potential elicited by changes in the ongoing sound. In this study, we developed an objective method of identifying CDR by combining ACC response with a TEN test, namely the TEN-ACC test, and investigated its feasibility in normal-hearing listeners. Subjects and Method Ten normal-hearing subjects participated in this study. All subjects underwent both behavioral TEN test and electrophysiological TEN-ACC test. The stimuli for the TEN-ACC test consisted of TEN and embedded pure tones with different frequencies/signals to noise ratios (SNRs). To identify the thresholds, the range SNR of stimulation was varied from 0 to 20 dB, in stages of 4 dB. Results The ACC responses of all subjects who participated in this study were well elicited by stimuli developed for the TEN-ACC test. We confirm that the pure-tones embedded in TEN elicited the objective ACC response. Conclusion The results of this study suggest that the novel TEN-ACC test can be applied to evoke ACC in normal-hearing listeners. Future research should incorporate hearing-impaired listeners to determine the feasibility of the TEN-ACC test as an objective method to identify CDR.