• Journal of Preventive Medicine and Public Health
• /
• v.10 no.1
• /
• pp.94-101
• /
• 1977

Noise pollution, both in the environment and in the workplace, has been recognized as a major health hazard -one that can impair not only a person's hearing but also his physical and mental well-being. As industrialization progresses, the prevalence rate of occupational diseases is increasing, especially hearing loss, which has the highest prevalence rate among the occupational diseases. The major cause of noise is the construction of various large industries without any regulation of noise sources. Therefor, we must establish an enactment to control mechanical noise sources. as soon as possible. For the purpose of controlling the noise source, we must have exact data about such things as the sound level, the frequency of the peak sound and the revolutions per minute (r.p.m.) of the machine (a measure of the power of its motor). This study was undertaken in order to define the noise characteristics, the power of the machine's motor, the change of the sound level and the peak sound as the r.p.m. increases, and the permissible exposure time. The sample size of this study was 74 machines at 11 plants in 6 industries. The results are as follows; 1. The breakdown of the types of mechanical noise noted was : 63.6% continuous normal sound, 26.9% intermittent sound, 4.7% continuous repeating sound and 4.6% impulsive sound. 2. With respect to the type of industry, the overall sound level was the highest in the mechanical industry, with $103.8{\pm}2.8dB(A)$, and lowest in the textile industry, with $89.2{\pm}1.43dB(A)$. 3. With respect to the type of machine, the highest sound level was 124 dB(A) caused by Gauzing(II), in the mechanical industry, and the lowest was 76 dB(A) caused by Attachment (Jup Chack) (I) in the timber industry. 4. The shortest permissible exposure time to Gauzing(II) in the mechanical industry was less than 15 minutes. 5. Among 74 machines, 68.2% of the peak sound was situated in the high frequency range (52.7% at 2 KHz, 4.1% at 4 KHz and 1.4% at 8 KHz). 41.8% of the peak sound was in the middle frequency range (4.1% at 250Hz, 14.8% at 500Hz and 22.9% at 1KHz). 6. If one machine had two motors or more, the peak sound was shifted to the low frequency range. 7. As the r.p.m. increased, the overall and peak sound levels were increased without any change of the frequency of the peak sound. 8. Whenever the machines had the same kind and the same r.p.m., the overall and peak sounds were changed by the physicochemical characteristics of the raw materials and the management.

• Journal of Korean Society of Forest Science
• /
• v.104 no.2
• /
• pp.277-284
• /
• 2015

This study aims to evaluate the impact of forest therapy on neuro-cognitive, psychosocial, and physiological aspect of adolescent internet addiction risk group. We have classified potential and high risk user group as internet addiction risk group according to the criteria of Korean Internet Addiction Proneness Scale(K Scale). Based on the results of k-scale from the adolescents in metropolitan area from May to July 2013, 25 people were selected as Internet addiction risk group. We have randomized 13 participants joining forest therapy camp and 12 participants not joining one, and analyzed the change of the two groups with Continuous Performance, Kimberly S. Young, Connor-Davidson Resilience, Relationship Change Scale, heart rate variability and cortisol. Statistically significant changes were observedd in neuro-cognitive, psychosocial, and physiological variables, Through this study, we can consider that the therapy healing may relieve the level of internet addiction and can be an alternative to control emotional stability and impulsive behavior.