• 한국공작기계학회논문집
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• 제17권5호
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• pp.107-115
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• 2008

In this research, it has been developed the tongs mechanism by a friction force for curbstone working. This tongs apparatus was farmed to grip and rotate the rectangular curbstone. Specification of this tongs apparatus has been determined by considering a loading weight and reversal load preventing reversal of 1.5 ton excavator. And, specification of the linear actuator has been determined with considering mechanical structure and the operation power demanded by the grip pad friction of tongs apparatus. The safety of the part has been examined from the 3D numerical simulation of the tongs apparatus. The operation system has been arranged to grip and rotate curbstone by on-off switching. The prototype has been established to carry out experiment after installing 1.5 ton excavator.

• 한국산업보건학회지
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• 제21권2호
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• pp.110-115
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• 2011

Objectives: The aim of this study is to survey for finding asbestos containing equipment at the laboratories using picture based questionnaire and polarized light microscopic analysis. Methods: This study was conducted from 2009 to 2010 at a university in Seoul. In 2009, picture based questionnaire was distributed to 100 laboratories during the regular laboratory air quality monitoring. In 2010, we emailed all professors of the same university who have laboratories to participate voluntarily this survey. For the laboratories consented to participate survey, picture based questionnaire was distributed and collected. Suspected asbestos containing material and apparatus were collected at the laboratories which replied they have suspected material and equipment. Collected samples were analyzed with polarized light microscope at the laboratory accredited by ministry of employment and labor in Korea. Results: Total of 18 out of 100 laboratories reported that they had suspected asbestos containing equipment in 2009. Twenty-three samples were collected and three samples (13%), one heating mantle and two pairs of insulation gloves, contained asbestos. Thirty four laboratories reported they had suspected asbestos containing material or equipment in 2010. Sixty samples were collected and four of them (6%), two pairs of insulation gloves, one packing rope in dry oven and, one pair of tongs, contained asbestos. All founded asbestos was chrysotile and the content of chrysotile was more than 90% for all equipment except heating mantle which has less than 1%. Conclusions: We confirmed that asbestos was still used at the laboratories though strict regulations on asbestos use in Korea. The method of picture based questionnaire invented in this study could be applied for asbestos survey to other research institute or university where there are many laboratories because of its simplicity and accessibility without huge man power, cost and time.