• Safety and Health at Work
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• 제10권3호
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• pp.389-392
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• 2019

When conducting an exposure assessment, the primary goal of the industrial hygienist is to fully characterize the worker's exposure during a work shift to compare it with an occupational exposure limit. This applies regardless of the duration of the work activity as an activity that is relatively short in duration can still present exposure in excess of the occupational exposure limit even when normalized over an 8-hr shift. This goal, however, is often impeded by the specification of a minimum sample volume in the published sampling method, which may prevent the sample from being collected or submitted for analysis. Removing the specification of minimum sample volume (or adjusting it from a requirement to a recommendation), in contrast, allows for a broader assessment of jobs that consist of short-duration and high-exposure activities and also eliminates the unnecessary practice of running sampling pumps in clean air to collect a specified, minimum volume.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• 제61권12호
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• pp.669-673
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• 2018

Background and Objectives Tinnitus, a common complaint of workers who are exposed to noise, can cause substantial negative effects on the quality of life of these workers. The aim of this study was to analyze the characteristics of tinnitus in patients with noise-induced hearing loss and the relationship between tinnitus and the duration of noise exposure. Subjects and Method Thirty-three patients with subjective tinnitus and noise-induced hearing loss were included in this study. Tinnitus questionnaire, Tinnitus Handicap Inventory (THI) and audiological examinations were investigated according to the duration of noise exposure. Results There was a significant correlation between the tinnitus loudness and the duration of noise exposure. Patients who had longer periods of noise exposure had a louder tinnitus and higher THI score. However, there is no significant correlation between the characteristics of tinnitus and aging process. Conclusion The duration of noise exposure influences the loudness and distress of tinnitus. An awareness of tinnitus should be considered as part of hearing conservation program.

• 한국해안·해양공학회논문집
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• 제24권5호
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• pp.319-325
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• 2012

조간대 저서생물들의 서식환경을 결정하는 중요한 인자 중의 하나인 노출시간을 추정하는 공식을 개발하였다. 이 공식은 기존의 1시간 간격, 1년 기간 조위자료를 이용하여 노출시간을 추정하는 방법과는 달리 대부분 연안의 기본 조석 정보에 해당하는 주요 4분조 조화상수들을 이용하여 노출시간을 간단하게 계산할 수 있다. 서해안의 관측 조위자료를 이용한 노출시간과 본 연구에서 개발한 공식에 의한 추정결과를 비교한 결과 RMS 오차는 0.8-1.4%로 파악되었다. 본 공식은 장기간의 조위자료가 없는 조간대 지역에서 간단하면서도 정확한 노출 시간 및 침수시간 추정에 활용할 수 있다.

• 한국소음진동공학회논문집
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• 제15권5호
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• pp.550-557
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• 2005

Korean 'Law of Aviation' and 'Test Method of Measuring Noise and Vibration' designate to use WECPNL metric based on $L_{max}$ measurement for the accessment of aircraft noise in Korea. However, time duration of noise event can not be considered in $L_{max}$ metric in principle, compensation on the duration has been utilized. A study was done recently to evaluate appropriate duration compensation for the accessment of military aircraft noise under current metric of WECPNL and $L_{max}$. This study was carried out to evaluate what metric is the most appropriate to express aircraft noise including time duration of single noise event, computing and comparing noise exposure with 1 second noise measurement data of military aircraft in $L_{max}$, $L_{Aeq,\;T}$ and SEL. This study shows SEL is the most appropriate noise metric for the evaluation of noise exposure with time duration such as aircraft noise without compensation. It is suggested to use SEL noise metric instead of $L_{max}$ noise metric with duration compensation for the aircraft noise accessment either military aircraft or civilian aircraft.

• Clinical and Experimental Reproductive Medicine
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• 제39권1호
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• pp.1-9
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• 2012

The safety of human exposure to an ever-increasing number and diversity of electromagnetic field (EMF) sources both at work and at home has become a public health issue. To date, many in vivo and in vitro studies have revealed that EMF exposure can alter cellular homeostasis, endocrine function, reproductive function, and fetal development in animal systems. Reproductive parameters reported to be altered by EMF exposure include male germ cell death, the estrous cycle, reproductive endocrine hormones, reproductive organ weights, sperm motility, early embryonic development, and pregnancy success. At the cellular level, an increase in free radicals and $[Ca^{2+}]i$ may mediate the effect of EMFs and lead to cell growth inhibition, protein misfolding, and DNA breaks. The effect of EMF exposure on reproductive function differs according to frequency and wave, strength (energy), and duration of exposure. In the present review, the effects of EMFs on reproductive function are summarized according to the types of EMF, wave type, strength, and duration of exposure at cellular and organism levels.

• 한국산업보건학회지
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• 제11권1호
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• pp.26-33
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• 2001

The goal of this study was to evaluate the relationship between ambient hexavalent chromium concentration and the concentration of the chromium in whole blood, plasma, erythrocytes, and its urinary excretion of male rats after inhalation exposure of sodium chromate during 1, 2, and 3 weeks. 1. Differences of mean chromium concentration in urine, whole blood, erythrocytes, and plasma of male rats exposed to sodium chromate by exposure level were statistically significance, respectively. 2. At low and high exposure groups, differences of mean chromium concentration in urine, whole blood, erythrocytes, and plasma of male rats by duration of inhalation exposure were statistically significance, respectively. 3. Ratio of whole blood chromium to plasma chromium increased with the increased duration of inhalation exposure of sodium chromate. 4. Ambient hexavalent chromium was positively and strongly correlated with in erythrocyte chromium, and also erythrocyte chromium was strongly correlated with in whole blood chromium. In conclusion, this study showed that chromium in erythrocyte increased with the increased exposure level and exposure duration, therefore this study suggests that chromium in erythrocytes is a good biological exposure index of the internal dose from exposure to soluble hexavalent chromium compound.

• 생명과학회지
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• 제25권2호
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• pp.151-157
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• 2015

Zebrafish는 약리학 연구에 널리 사용되는 실험 동물 중 하나이다. Oxytetracycline은 넓은 항균 범위를 가지는 항생제로써 단백질 합성을 억제하여 정균 작용을 가진 항생제이다. 본 연구의 목적은 OTC에 노출이 되었을 때 zebrafish에게서 나타나는 행동변화와 내분비계의 변화를 관찰하였다. OTC (50, 100 or 200 mg/l)에 노출된 zebrafish의 행동변화를 확인하기 위해 novel tank test와 open field test를 진행하였다. 또한 내분비계의 변화를 확인하기 위하여 whole-body cortisol의 수치를 cortisol kit를 이용하여 측정하였다. Novel tank test 결과 상층부에서 머문 시간과 부동 시간에서 OTC를 약욕하였을 때 통계적으로 유의성이 있는 증가현상이 확인되었다. 반면에, 총 이동거리, 과행동 시간, 유영 속도 그리고 상하 변위에서 OTC를 약욕하였을 때 통계적으로 유의성 있는 감소 현상이 확인되었다. Open field test 결과 부동시간에서 OTC를 약욕 하였을 때 통계적으로 유의성 있는 증가 현상이 확인 되었다. 그러나 OTC를 약욕 하였을 때 총 이동거리, 움직인 시간, 유영 속도에서 통계적으로 유의성이 있는 감소 현상이 확인 되었다. Whole-body cortisol에서는 zebrafish에게 약욕을 하였을 때 증가하는 경향이 관찰되었다. 이러한 결과를 통하여 OTC가 zebrafish에게 화학적 스트레스로 작용한 것으로 사료된다.

• 한국환경과학회지
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• 제1권1호
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• pp.47-51
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• 1992

수중에 존재하는 휘발성 유기화합물은 샤워를 하는동안 공기로 방출되고 공기농도는 샤워 변수에 따라 달라지는데, 이는 휘발성 유기화합물의 호기농도의 변화를 야기 시킨다. 본 연구에서는 샤워를 하는 동안 공기중의 클로로포픔 노출에 영향을 미치는 주요한 샤워변수(물온다 및 노출시간)를 클로로포픔 호기농도를 측정하여 검토 하였다. 크롤로포름 호기농도는 물의 온도와 노출 시간이 증가함에 따라 증가 하였다. 가장 큰 클로로포름 호기농도 차이를 나타내는 두개의 흡기 노출 조건은 미지근한 물을 이용한 5분 동안의 노출과 더운 물을 이용한 15분 동안의 노출이었다. 클로로포름 호기농도는 후자의 노출후에 전자의 경우보다 거의 3배 정도 높았다. 주요 샤워변수와 수중농도로 조정된 호기농도 사이의 수학모델은 0.0001의 확률에서의 데이타와 훌륭한 일치되는 결과를 나타내었다.

• Journal of Preventive Medicine and Public Health
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• 제27권1호
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• pp.84-106
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• 1994

Hyperbaric oxygen (HBO) therapy for carbon monoxide (CO) poisoning eventually inducing the hypoxia-reoxygenation condition, may produce oxygen free radicals, which forms 8-hydroxydeoxyguanosine (8-OH-dG) by attacking C-8 position of deoxyguanosine (dG) in DNA. Effects of oxygen partial pressure or duration of HBO therapy with or without CO poisoning on the tissue 8-OH-dG formation were investigated. Male Sprague-Dawley rats were grouped and exposed to air (control group), 4000 ppm of CO for 10 to 30 minutes (CO only group), air for 30 minutes after 30 minute exposure to 4000 ppm of CO(CO-air exposure group), HBO after 30 minute exposure to 4000 ppm of CO(CO-HBO group), or HBO therapy fo. $10{\sim}120$ minutes(HBO only group). The 8-OH-4G concentrations in the brain and the lung tissues were measured with high performance liquid chromatography and electrochemical detector (ECD). Average concentrations of the 8-OH-dG of each group were statistically compared. In the brain tissues, 8-OH-dG concentrations of the CO only group, the CO-air exposure group, and the CO-HBO group did not significantly differ from those of the control group. Similar insignificance was also found between the CO-HBO group and the HBO only groups. No appreciable dose-response relationship was observed between the 8-OH-dG concentration and the oxygen partial pressure or the duration of HBO. However, the 8-OH-dG concentrations of the 30 minute CO only group were higher than those of the CO-air exposure group (p-value<0.05). In the lung tissues, there were no significant differences between the 8-OH-dG concentrations of the control group and those of the CO only group, the CO-air exposure group, and the CO-HBO group. However, mean 8-OH-dG concentration of the CO-air exposure group was significantly higher than that of the CO only group under the same CO exposure condition(p-value<0.05). With the duration of CO exposure, the 8-OH-dG concentrations of the lung tissues decreased significantly (p-value<0.05). The concentrations of 8-OH-dG in the lung tissues proportionally increased with the duration of HBO, but no such relation was observed with the oxygen partial pressure. These results suggest that the brain may be more resistant to oxygen free radicals as compared with the lungs, and that oxygen toxicity following HBO may be affected by factors other than oxygen free radicals.

• Reproductive and Developmental Biology
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• 제35권3호
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• pp.257-263
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• 2011

In general, the blood cell culture is a common method for animal chromosome preparation. However, every animal and its cells have unique physiological characteristics and functions. Hence, it is very difficult to find the suitable method of chromosome preparation using animal lymphocyte culture. This study was carried out to fine the suitable method of chromosome preparation using lymphocytes cultures in mammalians and aves including cattle, rat, mouse and chicken. To seek the optimal method of lymphocyte culture in each animal, $2^3$ factorial experiment was designed. The design evaluated three main effects in culture duration, kinds of mitogen supplements and colcemid exposure time with two levels within each effect. The mitotic index and the score of chromosome morphology were analyzed. In results, the suitable methods of lymphocyte culture for chromosome preparation were 72 hours culture, pokeweed mitogen(PWM) supplement and 90 minutes of colcemid exposure in cattle, 72 hours culture, PWM supplement and 50 minutes of colcemid exposure in chicken, 96 hours culture, concanavalin A supplement and 90 minutes of colcemid exposure in rat, and 72 hours culture, PWM supplement and 50 minutes of colcemid exposure in mouse, respectively. In conclusion, kinds of mitogen, culture duration and colcemid exposure time significantly affected the mitotic index and chromosome morphology, in animal lymphocyte culture. The interaction effects between/among treatment factors were also statistically significant.