• 운동영양학회지
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• 제14권2호
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• pp.95-101
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• 2010

The purpose of this study was to evaluate changes of body composition, cardio-respiratory function in ventilation threshold (VT) and maximal state exercise, systolic (SBP) and diastolic blood pressure (DBP) and serum nitric oxide (NO) production during acute reducing salt (RS) supplementation in college elite athletes. Variables of cardio-respiratory function during rest, ventilation threshold and maximal exercise was not shown a significantly difference between RS supplementation and non-supplementation, there was shown a significant increase in ventilation threshold time (p<0.05) and exhaustion time (p<0.05) during RS supplement compared to non-supplement. SBP and DBP were not shown a significant difference between RS supplement and non-supplement. This result suggests that acute intake of RS is not increased a blood pressure. Serum NO production was not significant difference in the RS supplement group, but it was shown a significantly increased levels (p<0.01, vs. recovery 30 min.) immediately after maximal exercise in the non-supplement group. This result suggests that acute intake of RS have important role in inhibition of serum NO production during maximal exercise. Conclusively, This study suggest that acute intake of RS was not influence in body composition variables, but it was positive effect in ventilation threshold time, exhaustion time, maintenance of blood pressure and inhibition of serum NO production in maximal treadmill exercise.

• 한국산업보건학회지
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• 제3권1호
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• pp.91-98
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• 1993

This study was carried out to investigate characteristic of vinyl chloride emissioned from poly vinyl chloride extrusion process and to evaluate the efficiency of local exhaust ventilation system. Before local ventilation facility was constructed in poly vinyl chloride extrusion process, the average worker exposure to vinyl chloride was 3.15 ppm, which exceeded Threshold Limit Value of American Conference of Gorvernmental Industrial Hygienists (ACGIH-TLV), 1 ppm. lt is possible that vinyl chloride residues in the poly vinyl chloride resin was released or degased due to extrusion heat. The larger the width of vinyl tube become, the higher worker exposure to vinyl chloride was. It is estimated that vinyl chloride from vinyl chloride resin increased as amount of poly vinyl chloride resin extruded in the extrusion process increased. Canopy hood was an appropriate type for poly vinyl chloride resin extrusion process. This local exhaust ventilation has fan static pressure of 7.65 inch wg($190mmH_2O$, total volumetric flowlate of 4,796 CFM ($135.8m^3$/min) and fan power requirement of 12 hp (8.952 Kw). After this local exhaust ventilation was constructed there, the average concentration of worker exposure to vinyl chloride was reduced to be 0.46 ppm, which was below the Threshold Limit Value, 1 ppm. Also, the removal efficiency rate of vinyl chloride attained by local exhaust ventilation was 85.3%. It was a statistically significant (p<0.01).

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2007년도 제48회 학술심포지움 및 추계국제학술대회
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• pp.25.2-25.2
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• 2007

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• Advances in environmental research
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• 제4권3호
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• pp.143-153
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• 2015

The ventilation system is a key device to ensure both healthful indoor air quality (IAQ) and thermal comfort in buildings. The ventilation system should make the IAQ meet the standards such as ASHRAE 62. This study deals with a new approach to modeling the ventilation and IAQ requirement in residential buildings. In that approach, Elite software is used to calculate the air supply volume, and CONTAM model as a multi-zone and contaminant dispersal model is employed to estimate the contaminants' concentrations. Amongst various contaminants existing in the residential buildings, two main contaminates of carbon dioxide ($CO_2$) and carbon monoxide (CO) were considered. CO and $CO_2$ are generated mainly from combustion sources such as gas cooking and heating oven. In addition to the mentioned sources, $CO_2$ is generated from occupants' respirations. To show how that approach works, a sample house with the area of $80m^2$ located in Tehran was considered as an illustrative case study. The results showed that $CO_2$ concentration in the winter was higher than the acceptable level. Therefore, the air change rate (ACH) of 4.2 was required to lower the $CO_2$ concentration below the air quality threshold in the living room, and in the bedrooms, the rate of ventilation volume should be 11.2 ACH.

• 한국환경보건학회지
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• 제41권5호
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• pp.299-304
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• 2015

Objectives: A people-counting system measures real-time occupancy through motion detection. Accurate people-counting can be used to calculate suitable ventilation demands. This study determined the optimum motion threshold for a people-counting system. Methods: In a closed room with two occupants moving constantly, different thresholds were tested for the accuracy of a people-counting system. The experiments were conducted at 150, 300, 450 and 600 lux. These levels of brightness included the illumination levels of most public indoor areas. The experiments were repeated with three types of clothing coloration. Results: Overall, a threshold of 16 provided the lowest mean error percentage for the people-counting system. Brightness and clothing color did not have a significant impact on the results. Conclusion: A people-counting system could be used with threshold of 16 for most indoor environments.

• 한국산업보건학회지
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• 제4권1호
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• pp.71-80
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• 1994

This study was conducted to evaluate worker exposure to welding fume in automobile body shop and to evaluate metal components by type of welding. The results are summarized as follows: 1. Average concentrations of total welding fume without and with ventilation were $5.2mg/m^3$ and $2.49mg/m^3$, respectively. Thus, the average reduction rate of total fume by ventilation was 52.1 %. 2. The highest fume concentration was indicated at shielded arc welding, followed by $CO_2$ gas welding, argon arc welding, and spot welding in order of decreasing concentration. 3. Average respirable fume concentrations without and with ventilation were $2.97mg/m^3$ and $1.64mg/m^3$, respectively. 4. Further analysis of welding fume indicated that total fume consisted of $Fe_2O_3$, ZnO, Mn, Pb, and CuO, in order of decreasing amount. Combined effect of metals was below the American Conference of Governmental Industrial Hygienists (ACGIH)Threshold Limit Values (TLVs).

• 대한통합의학회지
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• 제9권3호
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• pp.69-78
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• 2021

Purpose : The purpose of this study was to investigate the effect of stair exercise and Kegel combined exercise on the maximum voluntary ventilation (MVV) and limits of stability (LOS). Methods : 23 female students participated in this experiment. MVV was measured with a spirometer. The LOS was measured with a Biorescue. Subjects were randomly assigned to two groups. 12 subjects were assigned to the experimental group and 11 subjects were assigned to the control group. The experimental group performed 5 minutes of stair exercise and 5 minutes of Kegel exercise. The control group performed 10 minutes of stair exercise. After 5 minutes of exercise, 1 minute of rest was provided. Both groups exercised for 5 minutes according to the metronome beat 130 during the stair exercise. After 5 minutes of rest after exercise, MVV and LOS were measured again in the same way. The measurement sequence was also randomly alternated. Results : Significant differences were found within and between groups in the experimental group in MVV (p<.05). In LOS, significant differences were confirmed in left, right, forward, backward, and total LOS in the experimental group (p<.05). In the control group, there were significant differences in left, forward, and total LOS (p<.05). However, there was no significant difference between groups (p>.05). Conclusion : Based on the results of this study, it was confirmed that the stairs and Kegel combined exercise had a positive effect on MVV and LOS. However, in the short term, it was found that the stair and Kegel combined exercise was insufficient in time and the threshold of exercise to show the difference between groups in LOS. Therefore, additional research should be conducted by modifying the limitations of this study.

• Elastomers and Composites
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• 제37권2호
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• pp.107-114
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• 2002

청정실(Clean room)에 사용되는 환기팬용 모터의 방진고무부품의 수명을 예측하기 위해서 가속 열 노화 시험을 수행하였다. 방진고무부품은 EPDM으로 만들었다. 노화 수명을 판단하기 위한 한계점을 20%의 압축 영구 줄음률로 하여 절대 온도의 역수 값으로 아레니우스 선도를 유도하였다. 아레니우스 관계식으로부터 방진고무부품의 다양한 온도에서의 수명과 활성화에너지를 구하였다. 그리고 수명을 판단하는데 있어 상당한 시간을 대체할 수 있는 가속 시험법을 설계하였다. 또한 방진고무부품에 첨가되는 노화 방지제가 수명에 미치는 영향을 알아보았다.

• 터널과지하공간
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• 제22권3호
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• pp.163-172
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• 2012

국내 대단면 지하 석회석광산 갱내에서 디젤장비의 사용이 증가함에 따라 배출 오염물질 및 열방출로 인한 작업환경의 악화 문제가 심각해지고 있다. 본 연구에서는 적정 소요환기량의 확보를 통한 갱내 환경의 최적화를 위한 기초연구로 갱내 환기망내 기류분포와 디젤장비의 배출가스 농도분포를 측정하고, 지하 심부화와 기계화에 따른 온 습도 변화를 고려하여 갱내 소요환기량을 추정하였다. 배기팬의 용량 부족 및 갱도 관리의 문제로 인하여 갱내 다수의 지점에서 기류정체가 심하고, 주요 갱도에서의 기류방향이 장비의 이동에 따른 순간적인 변화가 크며 계절별 변화 또한 큰 편이다. 디젤 배출가스인 CO의 경우 적재작업시 규제농도 50 ppm을 자주 초과하였으며, $NO_2$의 경우 천공 및 적재작업동안 대부분 규제농도 3 ppm을 초과하였다. 광산보안법규를 적용하여 구한 갱내 소요환기량에 비하여 실제 환기량이 심각하게 부족하였으며 자연환기력의 영향에 따라 환기량 부족문제는 외부 온도가 낮은 겨울철이 상대적으로 덜 심각하였다.

• 한국산업보건학회지
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• 제16권1호
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• pp.36-43
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• 2006

The principal aim of this field study was to determine the concentrations and emissions of gaseous contaminants such as ammonia and hydrogen sulfide in the different types of pig buildings in Korea and allow objective comparison between Korea and the other countries in terms of pig housing types. This field study was performed from May to June and from September to October in 2002. Pig buildings investigated in this research were selected in terms of three criteria; manure removal system, ventilation mode and growth stage of pig. Measurements of concentration and emission of ammonia and hydrogen sulfide in the pig buildings were done in 5 housing types and the visited farms were 15 sites per each housing type. Concentrations of ammonia and hydrogen sulfide were measured at three locations of the central alley in the pig building and emission rates of them were estimated by multiplying the average concentration($mg/m^3$) measured near the air outlet by the mean ventilation rate($m^3/h$) and expressed either per pig of liveweight 75kg(mg/h/pig) or per area($mg/h/m^2$). Concentrations of ammonia and hydrogen sulfide in the pig buildings were averaged to 7.5 ppm and 286.5 ppb and ranged from 0.8 to 21.4 ppm and from 45.8 to 1,235 ppb, respectively. The highest concentrations of ammonia and hydrogen sulfide were found in the mechanically ventilated buildings with slats; 12.1 ppm and 612.8 ppb, while the lowest concentrations of ammonia and hydrogen sulfide were found in the pig buildings with deep-litter bed system(2.2 ppm) and the naturally ventilated pig buildings with manure removal system by scraper(115.2 ppb), respectively(p<0.05). All the pig buildings were investigated not to exceed the threshold limit values(TLVs) of ammonia(25 ppm) and hydrogen sulfide(10 ppm). The mean emissions of ammonia and hydrogen sulfide per pig(75kg in terms of liveweight) and area($m^2$) from pig buildings were 250.2 mg/h/pig and 37.8 mg/h/pig and $336.3mg/h/m^2$ and $50.9mg/h/m^2$, respectively. The pig buildings with deep-litter bed system showed the lowest emissions of ammonia and hydrogen sulfide(p<0.05). However, the emissions of ammonia and hydrogen sulfide from the other pig buildings were not significantly different(p>0.05). Concentrations and emissions of ammonia and hydrogen sulfide were relatively higher in the pig buildings managed with deep-pit manure system with slats and mechanical ventilation mode than the different pig housing types. In order to prevent pig farm workers from adverse health effect caused by exposure to ammonia and hydrogen sulfide in pig buildings, they should wear the respirators during shift and be educated sustainably for the guideline related to occupational safety.