• 한국환경보건학회지
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• 제38권2호
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• pp.118-127
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• 2012

Objectives: This study was undertaken to assess the sanitary conditions in the kitchens of food court/cafeterias and determine seasonal variations. Methods: We measured environmental factors (air temperature, relative humidity, illumination intensity, noise level), and dropping airborne microbes (bacteria and fungi) in the kitchens of eight food court/cafeterias in four seasons (January, April, July, and October). Air temperature and relative humidity were measured with in/out thermo-hygrometers at 1.2-1.5 m above floor level. Illuminance measurement was performed through the multiple point method of Korean Standards (KS). Noise level was measured by the standard methods for the examination of environmental pollution (noise and vibration) of Korea. The estimation of dropping airborne bacteria and fungi was performed through use of Koch's method. Results: The highest kitchen air temperature was in July, and the lowest in January. The average temperature surpassed $21^{\circ}C$ throughout the seasons, suggesting a higher temperature than required for the safe handling of food. Humidity in all the kitchens was measured in the range of 50-60%. Half of the kitchens showed illumination intensities below 300 Lux in April. It was found that the sound pressure level of noise in almost all of the kitchens was higher than 85 dB (A). The highest levels of dropping airborne bacteria and fungi were noted in July. The numbers of airborne bacteria were higher than those of fungi. The levels of dropping airborne bacteria and fungi were affected by air temperature, relative humidity, season, and place. Conclusions: This study indicates that the kitchen environments were unqualified to supply safe food. The hygiene level of the kitchens should be improved.

• 환경위생공학
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• 제1권1호
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• pp.81-96
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• 1986

510 random samples were studied during the months of may through November 1985 at the various industries and conclustions were made as follows; 1. $43.94\%$ of the plants studied operated their plants with semiautomatic control system, and better efficiency were observed at the plants where automatic control systems emplorid and also large industries showed more tendency adopting the automatic plant control system. 2. Overall efficiency of the treatment plants were seen much higher at the first and secand discharge class categories then the lower discharge classes, $80.79\%$ of the plants were see their daily plant operation being controlled by the operator himself. 3. The main causes of the plant stopage and in efficient discharge control were found to be malfunctioning of the plants machineries and equipment or inadequate decision made by the management to save chemicals or electricity. 4. The study showed $60\%$ of the industry treated their wastwater wholly and the rest discharged only with dilution without receiving any further treatment, and this tendency pronounced at the 4th and 5th class discharge category industries. 5. $66.17\%$ of the industry had their storage capacity to accommodate the waste discharge during plants outage while $92.67\%$ of the air pollution discharge industries had no means for the plant outage. 6. $56.77\%$ of the studied industry maintained 24 hour operation of their discharge control systems whill $18.67\%$ of air pollution discharge industries and $10.53\%$ of the waste water discharge industries showed no control effort during the night.

• 한국환경과학회지
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• 제33권4호
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• pp.269-277
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• 2024

Scientific forensic techniques are used to verify environmental impact of groundwater pollution, surface water pollution, air pollution, noise, and vibration according to residents' complaints in connection with construction and civil engineering works. In this study, we investigated the contamination of groundwater and the lowering of the groundwater level in an area surrounding a tunnel excavation site for the Andong-Yeongdeok national road, using a forensic hydrogeological technique. We reviewed the groundwater level and water quality of well GW1 in the area surrounding the tunnel excavation site as well as tunnel construction information and then we analyzed the correlations among the obtained data. Before tunnel excavation, the water level of well GW1 was lower than the tunnel elevation. Considering the relationship between the precipitation, tunnel discharge, tunnel depth, and groundwater level of well GW1, the groundwater flowed from the tunnel to well GW1. Moreover, the tunnel discharge and groundwater levels were not related to each other. The pH of well GW1 was 8.4 before tunnel excavation. During excavation, the pH declined to 8.1-8.2 at the beginning, and increased to 8.8 at the end of the excavation. The fluorine concentration in well GW1 was 2.49 mg/L, 1.91-3.22 mg/L, and 1.7-2.67 mg/L, respectively, before, during, and after the excavation. The sulfate ion concentration was very high, over 2,000 mg/L, before and during the excavation; after the excavation, it was between 200 and 323 mg/L. Turbidity was 1.47, 10.5, and 4.51 NTU before, during, and after tunnel excavation, respectively. Therefore, the excavation of this tunnel is not related to the groundwater quality of well GW1.

• Journal of Preventive Medicine and Public Health
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• 제10권1호
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• pp.94-101
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• 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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.70-77
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• 2011

When a train passes a conventional tunnel at high speed, an environmental noise issue arises by pressure variation and micro-pressure waves at the exit of the tunnel. It is known that this issue can be reduced by using dummy tunnel duct on the tunnel entrance. We studied the variances of micro-pressure waves at the exit of tunnel and pressure variation within the tunnel, by altering surface area and length of the dummy tunnel duct. For analyze this train-tunnel relation problem, axi-simmetric steady compressible flow solver was used. Changing the length of the dummy tunnel duct can adjust pressure variation, changing the surface area of the dummy tunnel duct can adjust volume and pressure variation of the micro-pressure wave. Thus, optimized surface area and length of the dummy tunnel duct can simultaneously reduce environmental noise pollution by micro-pressure wave and issues by the pressure variation.

• 수산해양기술연구
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• 제53권1호
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• pp.19-40
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• 2017

A scientific and objective sound exposure criterion for underwater sound damage on fish has been required since there has been many disputes between an underwater sound maker and a fish damage receiver. The existing criteria are still incomplete scientifically owing to a degree of variability of underwater sounds, diversity of fish hearing sensitivity and damage types, etc. This study reviews existing studies on a hearing mechanism of fish species, manmade underwater sound characteristics and sound exposure assessment parameters, and recent sound exposure criteria. A governing equation for damage coverage estimation and damage coverage dependency on sound source level, ambient noise and transmission loss are also reviewed and interpreted based on sound exposure environments. The foreign and Korean (National Environmental Dispute Medication Commission) criteria are reviewed and compared based on scientific aspects. In addition, the deficit and limit of Korean criteria are presented. The objective of this study is to give a direction for related researches and legislation of sound exposure criteria on fish.

• 한국항공운항학회지
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• 제28권4호
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• pp.171-175
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• 2020

The present and future cities are expanding, and the noise and environmental pollution in cities are getting worse day by day, causing saturation of road and subway traffic. As a result, citizens are spending a great deal of time and money. The use of the sky as a measure to solve this problem has become a reality. However, airplanes that require airstrips and noisy helicopters are difficult to use in cities. As a solution, PAVs and UAMs that generate low noise and enable vertical takeoff and landing using electric energy, motor, hybrid, and hydrogen energy, are attracting attention, with its practicality being promoted in many countries. The development of urban environment and technology has led to the emergence of Personal Air Vehicle (PAV), Vertical Takeoff and Landing (eVTOL), and Urban Air Mobility (UAM) for shipping. Though currently at the level of testing, general commercialization of these air transport means is expected in the next five to fifteen years. This study suggests a plan on the application of human factors to the introduction of PAV and UAM.

• 대한조선학회논문집
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• 제60권5호
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• pp.388-396
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• 2023

As the government encourages the replacement of small FRP ships with eco-friendly aluminum ships due to environmental pollution problems, interest and demand for small aluminum ships are increasing. It is known that the vibration and noise of aluminum ships are somewhat vulnerable than that of FRP ships. However, in the process of designing and manufacturing small aluminum fishing boats, vibration and noise are not reviewed. In this study, vibration analysis is performed on three existing aluminum fishing boats, and the vibration characteristics of small aluminum boats are identified. Through this study, we intend to contribute to improving the vibration quality of small aluminum ships.

• 한국컴퓨터정보학회논문지
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• 제28권12호
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• pp.97-104
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• 2023

본 논문은 지향성 스피커를 이용한 유해조류 퇴치 시스템을 제안한다. 유해조류 퇴치를 위한 기존 사운드 시스템은 소음공해로 인한 문제와 단조로운 소리로 인하여 조류의 학습효과로 효과성이 저하되는 단점을 가진다. 본 논문에서는 지향성 스피커를 이용하여 주변의 소음을 최소화하고 스피커 구동 장치에 대해 상하 및 좌우 각도를 자유롭게 하여 활용성을 극대화하였다. 또한 다양한 스캐닝 패턴을 이용하여 학습효과로 인한 성능저하 문제를 해결하였다. 향후, 원격제어 기능과 조류 종류를 인식할 수 있는 딥러닝 모델을 적용하여 중앙통제가 가능한 플랫폼으로 발전시키고자 한다.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2394-2398
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• 2013

Nicotine is the main component of environmental tobacco smoke, and its presence in indoor air is widely used as a secondhand-smoke indicator. Environmental tobacco smoke is a major source of indoor air pollution, but sufficient investigation of the uncertainty of its measurement, which mirrors the reliability of nicotine measurement, has not been performed. We calculated the uncertainty of measurement of indoor air nicotine concentration at low, medium, and high concentrations of 11.3798, 10.1977, $98.3768{\mu}g/m^3$, respectively, and we employed the Guide to the Expression of Uncertainty in Measurements (GUM), proposed by the International Organization for Standardization (ISO). The factors considered in determining the uncertainty were uncertainty of the calibration curve (calibration curve and repeated measurements), desorption efficiency, extraction volume, and sampling airflow (accuracy and acceptable limits of flowmeter). The measurement uncertainty was highest at low concentrations; the expanded measurement uncertainty is $0.9435{\mu}g/m^3$ and is represented as a relative uncertainty of 63.38%. At medium and high (concentrations, the relative uncertainty was 13.1% and 9.1%, respectively. The uncertainty of the calibration curve was largest for low indoor nicotine concentrations. To increase reliability of measurement in assessing the effect of secondhand smoke, measures such as increasing the sample injection rate ($1{\mu}L$ or more), increasing sampling volume to increase collected nicotine, and using gas chromatography-mass spectrometry (GC/MS) or GC/MS/MS, which has a lower quantitation threshold, rather than gas chromatography with nitrogen phosphorous detector, should be considered.