• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.67-70
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• 2010

Spandex yarn requires a twisting process during winding and unwinding processes at the textile industry. The air-twist nozzle is widely used as part of the winding and unwinding. This paper describes computational approach to design the geometry of the air-twist nozzle. The nozzle has circular yarn-channel and the air-inlet which is perpendicularly connected to the yarn-channel with yarn-loading slit. The air-inlet of the nozzle is designed while measurements of the yarn-channel are fixed. The airflow inside the air-twist nozzle is simulated by using Computational Fluid Dynamic model. The Ansys CFX was used to perform steady simulations of the airflow for the air-twisting process. The vortical structure and the airflow pattern such as velocity streamline, vorticity, velocity of the air-twist nozzle are discussed. Computational results are compared with experimental results in this paper.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1934-1938
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• 2008

Formation of air bubble is the one of common defects in UV nano imprint lithography. Location of dispensing and volume of droplets are among the most important parameters in the process. ]n this study, UV curable resin droplets with different volumes were dispensed at different locations and pressed to investigate air bubble formation. By varying volume of droplet and dispensing location, process conditions were found for minimum air bubble area.

• 한국물환경학회지
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• 제28권3호
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• pp.367-374
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• 2012

A flotation process has a shorter processing time and needs less space than a sedimentation process. Dissolved air flotation process (DAF) is an efficient flotation method and used in a conventional wastewater treatment process. However, DAF requires the circulation of water containing compressed air and requires expensive installation and operation cost. Plasma Air Flotation (PAF) process is able to float flocs by micro bubbles generated from underwater plasma without the circulation of bubbly water and additional saturators. Therefore, PAF can be an alternative solution overcoming economic barriers. In this study, Humic acid removal efficiency by PAF process was compared with that of sedimentation process. 44.67% and 87.3% reduction rate based on UV 254 absorbance has been measured in sedimentation and PAF respectively. In particular, PAF in the flocculation zone can dramatically remove humic acid from water. In flocculation zone, PAF can separate organic matters but sedimentation cannot.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 하계학술발표대회
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• pp.176-176
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• 2005

• 대한안전경영과학회지
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• 제12권2호
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• pp.153-159
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• 2010

The air logistics process is complex and needs many informations because various agencies participate in the logistics service and many stakeholders in air logistics. But it is hard to improve the infra of facilities because of an enormous expense, so air logistics process has to simplify for growing air freight. Nevertheless some documents are same, they should be changed due to different format. Also documents have to change even though different documents have same informations. Consequently, errors are increased because the names of the same data are different from each other and stakeholders have to reproduce the documents. In order to mitigate these problems, we selected documents and analyzed document data for the interface optimization in general air logistics process. Next, we unified the data names and defined contents of data. Also we set the type of the defined data on DB type, and gave the code to the defined data. It made easy to exchange informations among the stakeholders to match documents corresponding with the defined data. Finally, the simulation of air logistics processes was performed the quantitative analysis of the data that occur in the air logistics. In conclusion, we expect to reduce the inefficiency such as reproduction of data and the errors by improving the interface of information.

• Journal of Mechanical Science and Technology
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• 제15권4호
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• pp.459-464
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• 2001

The effects of internal air-pressing on deep drawability are investigated in this study to increase the deep drawability of aluminum sheet. The conventional deep drawing process is limited to a certain limit drawing ratio(LDR) beyond which failure will occur. The intention of this work is to examine the possibilities of relaxing the above limitation through the deep drawing with internal air-pressing, aiming towards a process with an increased drawing ratio. The idea which may lead to this goal is the use of special punch that can exert high pressure on the internal surface of deforming sheet during the deep drawing process. Over the ranges of conditions investigated for Al-1050, the local strain concentration at punch nose radius area was decreased by internal air-pressing of punch, and the deep drawing with internal air-pressing was proved to be very effective process for obtaining higher LDR.

• 한국정밀공학회지
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• 제24권9호
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• pp.103-109
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• 2007

LCD (Liquid Crystal Display) is widely used electronic product. It needs too many processes such as PECVD (Plasma Enhanced Vapor Deposition), Sputtering, Photo-lithography, Dry etch. Each process is important but inspection process is more important because most companies emphasis on the six sigma. Recently, LCD inspection system is composed with inlet, inspector, outlet air pads. LCD is inspected on air pad which is shooting air from air hole. This paper studies on pad design of air bearing for LCD inspection to minimize LCD fluctuation. This design is able to reduce fluctuation and then satisfies CCD inspectional range. Also inspection pad needs to adequate stable area.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.145-147
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• 2009

The benefits of hydroforming technology are known as weight and cost savings through part consolidation and reduced post-forming processes such as welding and piercing. Hydroforming technology has some weaknesses in terms of process cycle times. But, as the hydraulic system and process designs are continuously developed, the cycle time is also reduced to acceptable and competitive levels. Hot air bulging is one of recently developed hydroforming techniques. Hot air bulging in order to further extend the forming degrees of Al lightweight material is investigated. A heated tube is placed in a heated die and sealed at the ends by sealing cylinders. The tube is subsequently expanded against the die cavity wall by internal pressure provided by air medium. The result of this study shows that axial feeding speed and air pressure have an effect on formability of Al air bulging at elevated temperature.

• Journal of Biosystems Engineering
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• 제4권2호
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• pp.32-45
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• 1979

The major objective of this study was to develope a computer simulation model to analyze drying process in a deep bed with natural air. The approach used to describe the continuous drying process in a deep bed was to divide the process into many small processes and simulate them by consecutively calculating the changes of grain and air conditions that occurred during short increment of time. Success criterion of the drying system was based on grain deterioration estimated by drymatter decomposition during drying. The results of the experimental test showed that the model satisfactory.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2004년도 제5회 정기학술발표대회 논문집
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• pp.376-379
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• 2004

건설사업은 인간의 생활의 질을 높이고 편리한 인간생활을 위해서 필수불가결한 요소이지만 이러한 건설행위자체는 개발과정에서 환경오염에 커다란 영향을 미친다. 또한, 쾌적한 환경에 대한 욕구 증대로 사업수행시 대기관련민원의 증가로 인한 공사지연이 빈번히 발생하고 있어 건설사업에서의 대기환경관리 중요성이 크게 부각되고 있다. 이에 본 연구에서는 건설사업시 환경관리를 위한 관리지침개발을 위해 건설사업 추진시 발생하는 여러 가지 오염 중 대기오염에 대한 관계법령 및 규제사항 검토, 환경관리 주요검토항목 및 주요관리지침을 도출하는 과정을 통해 건설사업 단계별 행동관리지침을 개발하여 건설사업의 환경관리 체계를 구축하는 것을 목적으로 한다.