The noise of large and high-power machines was evaluated and the establishment of mitigation measures was studied. The noise level of large machinery and high-power machinery installed at domestic plant sites was investigated and compared with the noise disclosure regulations to see if they met the standards of the Occupational Safety and Health Act. This investigated the soundproofing design of large and high-power machines and the soundproofing design of complex noise of large machines installed in the plant, and prepared the design standards of the plant design company. In the future, we will compile a database of data to secure standards for research and plant design related to noise reduction, and propose noise improvement and management measures for large and high-power machines.

통상적으로 직업소음에 의한 청력손실을 최소화하기 위해서는 작업자가 8시간 동안 85 dBA 이상 소음에 노출되지 않도록 권고하고 있다. 이번 연구에서는 실습선박에서 7종류의 담당업무별 작업자들의 소음노출레벨을 측정하였다. 항해 중, 24시간 동안 작업자의 위치하는 A특성등가소음레벨(LAeq,i)과 소음장소의 지속기간(h) 및 소음기여도(Lex,24h,i)를 고려한 소음노출레벨(Lex,24h)을 측정하였다. 그 결과, 갑판사관 그룹 Lex,24h=56.1 dB, 갑판부원 그룹은 Lex,24h=58.9 dB, 실습항해사들은 Lex,24h=62.0 dB, 취사부원들은 Lex,24h=64.3 dB, 실습기관사그룹 은 Lex,24h=91.1 dB, 기관사관 그룹은 Lex,24h=91.1 dB, 그리고 기관부원 그룹은 Lex,24h=95.1 dB를 나타내고 있다. 따라서 기관 업무를 담당하는 기관사들, 기관부원들 그리고 기관실습생들은 반드시 청력보호구를 착용해야함을 알 수 있었다. 소음이 심한 기관실에서 청력보호구를 착용한다면 기관사관그룹은 Lex,24h=23.1 dB, 기관부원그룹은 Lex,24h=24.4 dB 그리고 기관실습생들은 Lex,24h=21.5 dB의 소음노출레벨을 줄일 수 있을 것으로 추정된다. 또한 실습생들의 거주구역인 제2 강의실 겸 식당구역에 바닥시공을 64 mm, A-60-class 뜬바닥 구조로 개선했다면 실습항해사들의 소음노출도는 Lex,24h=4.3 dB, 실습기관사들은 Lex,24h=1.8 dB 정도 추가적인 감소가 있었을 것이다.

Long-term exposure to loud noise affects performance since it changes arousal level, distracts attention, and also is able to evoke subjective stress accompanied by negative emotional states. The purpose of the study was to analyze dynamics of subjective and physiological variables during a relatively long-lasting (30 min) exposure to white noise (85 dB[A]). Physiological signals were recorded on 15 college students during 30 min of intense auditory stimulation. Autonomic variables, namely skin conductance level , non-specific SCR number, inter-best intervals in ECG, heart rate variability index (HF/LF ratio of HRV), skin temperature, as well as respiration rate were analyzed on 5 min epoch basis. Psychological assessment (subjective rating of stress level) was also repeated every 5 min. Statistical analysis was employed to trace the time course of the dynamics of subjective and autonomic physiological variables and their relationships. Results showed that the intense noise evoked subjective stress as well as associated autonomic nervous system responses. However it was shown that physiological variables endured specific changes in the process of exposure to the loud white noise. Discussed were probable psychophysiological mechanisms mediating reactivity to long-term auditory stimulation of high intensity, namely short-term activation, followed by transient adaptation (with relatively stable autonomic balance) and then a subsequent wave of arousal due to tonic sympathetic dominance.

To develop managing guidance of occupational noise exposure for metal working facility, we have studied about drafting contour map of noise exposure, methods of noise assessment and actual calculation method of time weighted noise exposure. Therefore we have suggested that contour maps of noisy workplace are very important for controlling metal working fluid facility and two kinds of noise assessment method, so called, personal and static exposure are necessary to avoid argument between workers and managing group. Finally we would like recommend that the Korean specfication of noise exposure should be modified to protect ONIHL(occupational noise induced hearing loss).