• Title/Summary/Keyword: environment condition

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Comparison of Friction and Wear Characteristics of Thin Film Coatings Using Tribotesters at Atmospheric/Vacuum Conditions (대기압/진공 조건의 트라이보 시험기를 이용한 박막 코팅의 마찰/마모 특성 비교)

  • Kim, Hae-Jin;Kim, Dae-Eun;Kim, Chang-Lae
    • Tribology and Lubricants
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    • v.35 no.6
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    • pp.389-395
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    • 2019

  • In various industries, thin film coatings are used to improve friction and wear characteristics. Various types of tribotesters are used to evaluate the friction and wear characteristics of such thin film coatings. In this study, we fabricated a micro-tribotester and Tribo-scanning electron microscopy (SEM) to compare the friction and wear characteristics of copper (Cu) coatings under an atmospheric pressure and a vacuum condition, respectively. The reliability of the different types of tribotesters was evaluated by performing calibrations for the sensor to measure the friction forces and normal loads. Using the two different types of devices, the friction and wear tests are conducted at the same experimental conditions excluding environment conditions such as the atmospheric pressure and vacuum condition. The friction coefficient at the vacuum condition is lower than at the atmospheric pressure. This difference in friction characteristics is due to the fact that wear phenomena occur differently according to the atmospheric pressure and vacuum condition. At the atmospheric pressure, the abrasive wear is the main wear mechanism. At the vacuum condition, the adhesive wear is the main wear mechanism. The reason for the difference in the wear mechanism of the Cu coating at the atmospheric pressure and the vacuum condition is that the oxidation phenomenon, which does not appear at the vacuum condition, occurs at the atmospheric pressure; therefore, the characteristics of the Cu coating change accordingly.

  • https://doi.org/10.9725/kts.2019.35.6.389 인용 PDF KSCI HTML

Physiological Responses and Subjective Sensations by Age through Seasonal Condition (환경온도에 따른 착의 생리반응과 주관적 감각의 연령별 비교)

  • Lee, Jung-Sug;Song, Min-Kyu;Kim, Hee-Eun
    • Fashion & Textile Research Journal
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    • v.11 no.5
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    • pp.833-839
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    • 2009

  • This study was to investigate the human's physiological responses and subjective sensations with wear trial through seasonal condition by age. Climate chamber was set $5^{\circ}C$, RH 45% for winter and $30^{\circ}C$, RH 65% for summer condition. Thirty male subjects were volunteered consisted of 10 people in their 20s, 40s, and 60s. In this study physiological responses such as rectal temperature, skin temperature, clothing microclimate, heart rate and blood pressure were measured. As for age, 60s was the highest in rectal temperature regardless of seasonal condition. In skin temperature, 40s was the highest in winter and 20s was the highest in summer. In clothing microclimate temperature and heart rate, 20s was the highest regardless of seasonal condition. And blood pressure was appeared the highest in 20s regardless of seasonal condition. Subjective sensations such as temperature sensation, wetness sensation and thermal comfort were measured. The subjects revealed that temperature sensation was higher 20s than 60s. Compare of other age group, 60s felt colder in the same environment and clothing. It suggested that temperature susceptibility in 60s became weakened showing no change sensation during the cold exposure. Wetness sensation was higher 20s than 60s. Thermal comfort of 60s was felt more discomfortable than any other age group. This means require the supplement of a suitable clothing in order to adjust to change of environmental conditions.

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