• Design & Manufacturing
• /
• 제8권2호
• /
• pp.37-40
• /
• 2014

A discharge electrode plays a role of shaving off workpiece with spark generated by current in discharge machining. Accordingly, for the discharge electrode, an electrode with excellent wear resistance is necessary. Generally, Graphite and Cu are used as the materials of the electrode, and recently Cu-W is mainly used as an electrode with excellent wear resistance. However, the form of the electrode generally used is produced mostly using cutting work, so a lot of costs incur if several similar forms are needed. Thus, this study developed a Cu-W electrode using Metal Injection Molding (MIM) process to produce similar forms with excellent productivity and a great quantity of electrodes in a similar form in discharge machining and carried out a discharge machining test. In developing an electrode applying MIM, predicting contraction of a product in a sintering process, a mold expansion ratio of 1.29486 was given, but the actual product showed a percentage of contraction 24% to 32%, which showed a difference of 3% to 5%. In addition, to verify wear resistance of the discharge electrode, abrasion loss was measured after the discharge.

• 한국기계가공학회지
• /
• 제17권4호
• /
• pp.1-8
• /
• 2018

In drilling Inconel 601, which is used for compressor cases in aircraft engines, a lot of cutting oil must be supplied. This prevents tools from wear and fracture due to the heat buildup resulting from the high-temperature resistance and toughness of this alloy. However, the cutting oil supply has compromised the machining environment. This has caused attention to shift to an environmentally friendly cutting fluid supply system called the Minimum Quantity Lubrication(MQL) system. The aim of this study was to find a more efficient drill processing method using MQL and to verify its performance. To that end, the properties of Inconel that make it difficult -to -drill were studied by a comparison with the drilling of SM45C. Specific factors (i.e., cutting force and tool wear) were examined in relation to the conditions in the MQL-based drilling system. Based on these results, a sealed cover and step feed were proposed as measures to increase the effectiveness of the MQL system. The efficiency of the proposed method was established.

• 한국의류학회지
• /
• 제28권2호
• /
• pp.280-291
• /
• 2004

Apparel goods are classified by many criteria for ease of merchandising implementation. Fashion and basic goods are also an oucome oi classification. Previous studies pnvide some criteria by which apparel products can be classified into fushion and basic goods. Among those ciiteria, seasonality, fashionability, clothing types, complexity in pnduction, simplicity of style, pioducuon volume, degree of style change by season, could be listed. This study, first explored how apparel merchandisers and designers define fashion and basic goods in relation with those criteria. Definitions of fashion and basic goods were explored in terms of design elements (i.e., style, color, material), production volume, sales ratio, proportion in product assortment, and contribution to profit. The study adopted a qualitative approach by use of eighteen infepth interviews with menhandisers and designers. Six were from women＇s wear brand, Seven from men＇s wear brand, and 5 from casual wear brand. All the interviewees agreed that they are using the classification of basic vs. fashion goods. However, they are using diverse terms to indicate the basic and fashion goods. The interviewees defined each group based on its contribution to total sales or profit complexity in design, production volume, and style change by season. Basic goods had a higher level of production quantity, contribute more to profit simpler design, and less style change by season than fashion goods.

• 한국방재학회 논문집
• /
• 제10권4호
• /
• pp.47-54
• /
• 2010

지정폐기물인 폐페인트를 이용한 단열골재 개발을 위한 자료를 제시하기 위하여 이를 위한 실험으로 함수비, 진밀도, 액성한계, 소성한계, 마모감량, 모래당량, 체가름 시험을 진행하였다. 함수비 시험은 80:20의 배합이 1.4이고, 쇄석 골재만 사용한 것은 1.0으로 폐페인트 단열골재의 용적비가 증가하면서 함수비의 증가도 많았다. 또한, 진밀도 시험은 혼입율의 증가에 따라 점점 상승하였고, 흡수율도 증가하였다. 이는 골재와 폐페인트의 특성상 발생되는 공극분포의 차이로 인한 현상으로 판단된다. 모래당량과 마모감량 실험에서는 마모감량은 쇄석골재만 사용한 경우는 13.5이고 20% 혼입한 경우는 14.4로 증가하지만, 이는 단열골재의 약한 조직으로 인한 현상이라 판단된다. 이러한 실험으로 볼 때, 도로공사 시방서의 동상방지층은 모래당량 20, CBR 10으로 만족하도록 규정하고 있어 본 실험은 전 배합에서 모두 품질기준에 만족하는 결과를 보였다. 현재 폐페인트는 단순 매립용하거나, 소각 처리되는 현 실정에서 골재로 활용할 수 있게 됨으로써 천연골재의 부족이나 자원의 낭비를 해소할 수 있을 것으로 파악된다. 기존의 자갈보다 단열효과가 뛰어나고, 가벼우며, 단단한 단열골재를 사용함으로써 재활용이 활발할 것으로 예상된다.

• 한국화재소방학회논문지
• /
• 제23권6호
• /
• pp.116-125
• /
• 2009

클랭커 애쉬를 이용한 인공 경량 골재 개발을 위한 자료를 제시하기 위하여 이를 위한 실험으로 함수비, 진밀도, 액성한계, 소성한계, 마모감량, 모래당량, 체가름 시험을 진행하였다. 함수비 시험은 80 : 20의 배합이 1.4이고, 쇄석 골재만 사용한 것은 1.0으로 클링커애쉬 경량골재의 용적비가 증가하면서 함수비의 증가도 많았다. 또한, 진밀도 시험은 혼입율의 증가에 따라 점점 상승하였고, 흡수율도 증가하였다. 이는 폴리스티렌 비드의 특성상 클링커애쉬와 경량골재 사이의 공극율의 증가로 나타난 현상으로 판단된다. 모래당량과 마모감량 실험에서는 마모감량은 쇄석골재만 사용한 경우는 13.5이고 20% 혼입한 경우는 14.4로 증가하지만, 이는 경량골재의 약한 조직으로 인한 현상이라 판단된다. 이러한 실험으로 볼 때, 도로공사 시방서의 동상방지층은 모래당량 20, CBR 10으로 만족하도록 규정하고 있어 본 실험은 전 배합에서 모두 품질기준에 만족하는 결과를 보였다. 현재 클링커 애쉬는 단순 매립용 골재나, 매립으로 폐기하는 현실정에서 골재로 활용할 수 있게 됨으로써 천연골재의 부족이나 자원의 낭비를 해소할 수 있을 것으로 파악된다. 기존의 자갈보다 단열효과가 뛰어나고, 가벼우며, 단단한 경량골재를 사용함으로써 재활용이 활발할 것으로 예상된다.

• 한국의류산업학회지
• /
• 제16권5호
• /
• pp.776-784
• /
• 2014

KS K 0051(2009) was established in 1990 and revised in 1994, 1999, 2004 and 2009. Recently the structure of apparel production and distribution are changing like as small quantity batch production, increase of importing abroad apparel and increase of on-line shopping mall. Based on Social and economic conditions, examine the potential for use of KS K 0051(2009) standard sizing system for female adult's garments are needed. Through which, it was intended to suggestion for the revision of standard sizing system for female adult's garments which can facilitate communication among consumer, producer and sellers. The improvement point was discussed through review of the current KS K 0051 (2009) and abroad standard sizing system for female adult's garments, ISO 3637(1977), ISO 4416(1981), BS EN 13402-2(2002), BS EN 13402-3(2004), JIS L 4005(2001) and GB/T 1335.2(2008). Also, the revision of standard sizing system for female adult's garments was suggested using data of 6th Size Korea. As a result of this study, in the revision, formal wear, casual wear, training wear and under wear were separated to simplify the classification and the classification of body type were excluded. Also, it is possible that size designation was simplified through optional notation and letter code based on bust girth could be marked together in casual wear.

• 산업경영시스템학회지
• /
• 제44권1호
• /
• pp.45-50
• /
• 2021

Machines and facilities are physically or chemically degenerated by continuous usage. The representative type of the degeneration is the wearing of tools, which results in the process mean shift. According to the increasing wear level, non-conforming products cost and quality loss cost are increasing simultaneously. Therefore, a preventive maintenance is necessary at some point. The problem of determining the maintenance period (or wear limit) which minimizes the total cost is called the 'process mean shift problem'. The total cost includes three items: maintenance cost (or adjustment cost), non-conforming cost due to the non-conforming products, and quality loss cost due to the difference between the process target value and the product characteristic value among the conforming products. In this study, we set the production volume as a decreasing function rather than a constant. Also we treat the process variance as a function to the increasing wear rather than a constant. To the quality loss function, we adopted the Cpm+, which is the left and right asymmetric process capability index based on the process target value. These can more reflect the production site. In this study, we presented a more extensive maintenance model compared to previous studies, by integrating the items mentioned above. The objective equation of this model is the total cost per unit wear. The determining variables are the wear limit and the initial process setting position that minimize the objective equation.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.977-980
• /
• 2004

Metalworking fluids (MWFs) are fluids used during machining and grinding to prolong the life of the tool, carry away debris, and protect the surfaces of work pieces. These fluids reduce friction between the cutting tool and the work surface, reduce wear and galling, protect surface characteristics, reduce surface adhesion or welding and carry away generated heat. Workers can be exposed to MWFs by inhaling aerosols (mists) and by skin contact with the fluid. Skin contact occurs by dipping the hands into the fluid, splashes, or handling workpieces coated with the fluids. The amount of mist generated (and the resulting level of exposure) depends on many factors. To reduce the environmental pollution wastes and the potential health risks associated with occupational exposures to MWFs, it is required to establish optimum MWFs supply method and condition with minimum quantity in all over the mechanical machining field including high-speed type heavy cutting process.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1803-1806
• /
• 2003

Metalworking fluids (MWFs) are fluids used during machining and grinding to prolong the lift of the tool, carry away debris, and protect the surfaces of work pieces. These fluids reduce friction between the cutting tool and the work surface. reduce wear and galling, protect surface characteristics, reduce surface adhesion or welding and carry away generated heat. Workers can be exposed to MWFs by inhaling aerosols (mists) and by skin contact with the fluid. Skin contact occurs by dipping the hands into the fluid, splashes, or handling workpieces coated with the fluids. The amount of mist generated (and the resulting level of exposure) depends on many factors. To reduce the environmental pollution wastes and the potential health risks associated with occupational exposures to MWFs, it is required to establish optimum MWFs supply method and condition with minimum quantity in all over the mechanical machining field including high-speed type heavy cutting process.

• Tribology and Lubricants
• /
• 제17권6호
• /
• pp.417-426
• /
• 2001

The effect of silver particle introduction on the rolling friction of AISI 52100 steel pairs has been investigated. Experiments ware performed in dry conditions using a thrust bearing-type rolling test rig at a load range of 12-960 N and a sliding velocity range of 8-785 mm/sec with pure (99.99%) silver particles. Results showed that introduced silver particles formed transfer layers, which protected the virgin bearing surfaces and resulted in the low lolling friction. By changing the quantity of silver particles, transitions in the rolling friction were found. Results also showed that the variations in normal load and rolling speed also affected the rolling friction behavior. Analyses of SEM and EPMA showed that the formation the transfer layer was mainly governed by the silver particle quantity, normal load and rolling speed, and this resulted in the different behavior of rolling friction. In this study, it was found that the low and stable rolling friction was resulted from the, shakedown phenomena occurred at the silver transfer layer.