• 한국정밀공학회지
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• 제27권1호
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• pp.11-17
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• 2010

This study investigates the non-traditional manufacturing process of dry wire electrical discharge machining (EDM) in which liquid dielectric is replaced by a gaseous medium. Wire EDM experiments of thin workpieces were conducted both in wet and dry EDM conditions to examine the effects of spark cycle (T), spark on-time ($T_{on}$), thickness of work pieces, and work material on machining performance. The material removal rate (MRR) in the dry wire EDM case was much lower than that in the wet wire EDM case. In addition, the thickness of workpiece and work-material were found to be critical factors influencing the MRR for dry EDM process. The relative ratios of spark, arc and short circuit were also calculated and compared to examine the effectiveness of processes of dry and wet wire EDM.

• Nutrition Research and Practice
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• 제6권4호
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• pp.366-374
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• 2012

In order to create a worker-friendly environment for institutional foodservice, facilities operating with a dry kitchen system have been recommended. This study was designed to compare the work safety and work environment of foodservice between wet and dry kitchen systems. Data were obtained using questionnaires with a target group of 303 staff at 57 foodservice operations. Dry kitchen facilities were constructed after 2006, which had a higher construction cost and more finishing floors with anti-slip tiles, and in which employees more wore non-slip footwear than wet kitchen (76.7%). The kitchen temperature and muscular pain were the most frequently reported employees' discomfort factors in the two systems, and, in the wet kitchen, "noise of kitchen" was also frequently reported as a discomfort. Dietitian and employees rated the less slippery and slip related incidents in dry kitchens than those of wet kitchen. Fryer area, ware-washing area, and plate waste table were the slippery areas and the causes were different between the functional areas. The risk for current leakage was rated significantly higher in wet kitchens by dietitians. In addition, the ware-washing area was found to be where employees felt the highest risk of electrical shock. Muscular pain (72.2%), arthritis (39.1%), hard-of-hearing (46.6%) and psychological stress (47.0%) were experienced by employees more than once a month, particularly in the wet kitchen. In conclusion, the dry kitchen system was found to be more efficient for food and work safety because of its superior design and well managed practices.

• 한국안광학회지
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• 제19권3호
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• pp.389-396
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• 2014

목적: 신축건물 재실자들의 안구건조증을 조사하고, 안구건조증이 작업생산성 및 일상적인 활동에 미치는 영향에 대해 알아보았다. 방법: 신축한지 3개월이 지난 건물에서 일 평균 8시간 이상을 근무하는 사무직 근로자 33명을 대상으로 하였다. 실내공기질은 알데하이드류와 온습도를 측정하여 평가하였다. 안구건조증은 Ocular Surface Disease Index(OSDI)를 이용하여 정상, 경도, 중등도 및 중증으로 분류하였고, 라식수술, 눈 화장, 일일 컴퓨터와 스마트폰 사용시간, 그리고 일일 평균 근무시간을 조사하였다. 작업생산성과 일상활동 관련 설문은 Work Limitation Productivity 설문을 사용하여 손실정도를 10점 척도로 체크하였다. 결과: 사무실의 폼알데하이드 농도는 $42.42{\pm}6.30{\mu}g/m^3$ 이었고, 온습도는 각각 $26.2{\pm}0.7^{\circ}C$와 $40{\pm}1%$ 였다. 안구건조증은 정상, 경도, 중등도 및 중증이 각각 15.2%, 18.2%, 18.2%, 48.5%였다. 안구건조증의 심한 정도와 작업생산성 및 일상적인 활동의 손실 정도는 각각 0.599와 0.655의 높은 상관성을 보였다(p<0.001). 안구건조증이 중증인 경우는 정상에 비해 유의하게 높은 작업생산성 손실과 일상활동 저해를 나타냈다(p<0.001). 안구건조증이 심한 경우는 정상에 비해 작업생산성 손실과 일상활동 저해가 3점 이상일 확률이 각각 3.26배(p=0.032)와 2.25배(p=0.045) 높았다. 결론: 신축건물 사무직 근로자들의 안구건조증은 작업생산성과 일상적인 활동에 영향을 미치는 것을 확인할 수 있었다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.19-24
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• 2003

Recently, various efforts to make more speedy and precision machine tool to improve productivity and also various efforts to solve environmental problem are going on, so that dry cutting in manufacturing industry, which needs environmental conscious design and development of manufacturing technique, is becoming a very important assignment to solve. Because dry cutting does not use cutting fluid, we need other methods that can be used instead of cutting fluid, which does cooling, lubricating, chip washing, and anti-corrosion. Especially, because turning is a continuous work, the consideration of tool life and surface roughness due to continuous heat and poor lubrication is important. The purposes of this paper are the consideration of how well the compressed air can work instead of cutting fluid, and also the development of the method to select the optimum machining condition by the minimum numbers of experiments through the Taguchi method.

• 한국안전학회지
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• 제34권3호
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• pp.28-35
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• 2019

Dry water is a core-shell structured powder which comprises a very fine water core covered with hydrophobic silica particles. Recently, the dry water has attracted attention as a new type of fire extinguishing agents. However, characteristics of the dry water as a fire extinguishing agent have not been revealed until now. To our best knowledge, this is the first work to uncover effects of particle size of the dry water on the fire extinguishing performance. Pristine dry water, which has heterogeneous particle size distribution, was carefully separated by sieving method into three fractions which were a small size (ca. $110{\mu}m$) fraction, a medium size (ca. $220{\mu}m$) fraction and a large size (ca. $400{\mu}m$) fraction. Microscopic observations confirmed the effective separation of dry water's particle size. In extinguishing tests of wood cribs fire, the medium size dry water showed most excellent fire extinguishing performance, as compared to other dry waters having small (ca. $110{\mu}m$) and large (ca. $400{\mu}m$) particle size. The good performance of the medium size (ca. $220{\mu}m$) dry water may be attributed to the balance between cooling effect of the water core and smothering effect of the silica particles. It is also revealed that small size dry water has poor flowability than large size dry water.

• 한국공작기계학회논문집
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• 제17권6호
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• pp.111-117
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• 2008

An automation process of filter unit is presented for the application of the assembling procedure and dry furnace work. By that automation procedure, it is expected to enhance working environment such as reducing laboring load, harmful gas, and burning scald. Furthermore, this automation process also minimizes via standardization of manufacturing process so that it may increase productivity and reliability. An automation process of filter unit is presented for the application of the assembling procedure and dry furnace work. Filter automation process also gives a good quality and productivity by simplifying to only one line from the complicated process such as filter cutting$\rightarrow$ adhering$\rightarrow$fabricating in a very small space. It is found that a new conceptual design of dry furnace shows the better quality like uniform heat distribution compared to the conventional design. It is also found that the present design gives a better working environment by adding cooling system.

• 한국기계기술학회지
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• 제13권4호
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• pp.49-55
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• 2011

Recently, various efforts to make more speedy and precision machine tool to improve productivity and also various efforts to solve environmental problem are going on, so that dry cutting in manufacturing industry, which needs environmental conscious design and development of manufacturing technique, is becoming a very important assignment to solve. Because dry cutting does not use cutting fluid, we need other methods that can be used instead of cutting fluid, which does cooling, lubricating, chip washing, and anti-corrosion. Especially, because turning is a continuous work, the consideration of tool life and surface roughness due to continuous heat and poor lubrication is important. The purposes of this paper are the consideration of how well the compressed air can work instead of cutting fluid, and also the development of the method to select the optimum machining condition by the minimum numbers of experiments through the Taguchi method.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.233-234
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• 2023

This paper confirms the application sites of dry coupler technology, which is a direct connection method using screw threads, and Unlike wet couplers, this method can stand on its own without proof support and continuous work on the upper part. Furthermore, concludes with personal considerations to improve constructability.

• Geomechanics and Engineering
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• 제16권3호
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• pp.321-329
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• 2018

Classic braced walls use struts and wales to minimize ground movements induced by deep excavation. However, the installation of struts and wales is a time-consuming process and confines the work space. To secure a work space around the retaining structure, an anchoring system works in conjunction with a braced wall. However, anchoring cannot perform well when the shear strength of soil is low. In such a case, innovative retaining systems are required in excavation. This study proposes an innovative earth-retaining wall that uses in situ soil confined in dual sheet piles as a structural component. A numerical study was conducted to evaluate the stability of the proposed structure in cohesionless dry soil and establish a design chart. The displacement and factor of safety of the structural member were monitored and evaluated. According to the results, an increase in the clearance distance increases the depth of safe excavation. For a conservative design to secure the stability of the earth-retaining structure in cohesionless dry soil, the clearance distance should exceed 2 m, and the embedded depth should exceed 40% of the wall height. The results suggest that the proposed method can be used for 14 m of excavation without any internal support structure. The design chart can be used for the preliminary design of an earth-retaining structure using in situ soil with dual steel sheet piles in cohesionless dry soil.

• Safety and Health at Work
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• 제7권4호
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• pp.389-393
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• 2016

Job hazard analyses were conducted to assess exposure to musculoskeletal disorder (MSD) risk factors in seven workers of three dry-cleaning establishments. In accordance with the Washington State Ergonomics Rule, the analyses were performed in two separate steps: (1) observation and checklist approaches were made to identify a "caution zone job" in the seven workers' pressing operations across the three shops; and (2) detailed posture and motion analyses were undertaken to determine a "MSD hazard" in one worker's operation using a video technique. One "caution zone job" was identified and it was the pressing operation job in which five physical risk factors were found in the pressing operations. The detailed analyses confirmed that one "MSD hazard", i.e., awkward posture in shoulders, was prevalent in the pressing operations of the three dry-cleaning facilities. It would be desirable to reduce MSD risk factors including awkward shoulder posture in the dry-cleaning industry.