• Journal of the Korean Society of Industry Convergence
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• v.23 no.3
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• pp.375-380
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• 2020

In this study, we tried to evaluate the mechanical properties of Polycarbonate(PC) and acrylonitrile-butadiene-styrene(ABS) plastic materials, which are frequently used as parts of home appliances and machinery, when repeated impacts were applied. A repeating impact tester for this research was designed and manufactured to apply repetitive impacts. Two types of plastic were repeatedly impacted under a constant load, and a tensile test was performed on the plastic material that was impacted. The tensile strength of PC plastic materials that received impact more than 2000 times was reduced by about 45 % and elongation was reduced by about 10 % when compared to impact free specimens. On the other hand, in ABS plastic, a reduction of tensile strength of about 20 % was observed at about 2,000 impacted specimen, but at about 20,000 repetitive impacted specimen, a tensile strength decrease of about 65 % was observed. And the elongation was reduced by 10 % due to the cyclic harding behavior of the material.

• Fashion & Textile Research Journal
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• v.18 no.6
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• pp.776-786
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• 2016

This study intends to suggest production process of circular knitted jackets and dimensional change data of finished clothes after washing. the study provides pattern design method of circular knitted jackets by applying dimensional change. By doing so, the purpose of this study is to increase production efficiency through accurate order in consideration of loss amount of the fabrics in production. With the three fabric materials selected, this study investigated dimensional change of circular knitted jackets after sewing and washing by varying the parts to be attached to padding cloth and with or without inner lining. As for the fabric F-C (including the spandex, thicker and weightier than the other two fabrics), front width shrunk by 4.6%, which showed the biggest shrinkage among the jackets made of test fabrics. Then it suggested design methods of circular knitted jacket patterns to which dimensional change is applied according to materials, and analyzed the amount of fabric required for production by comparison of the materials. When using the fabric F-C without inner lining, there is big dimensional change and more than double amount of fabric is required. It is expected that the research results will be a basic data for pattern design and production process of circular knitted clothing.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.987-992
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• 2022

STS 410, a representative martensitic stainless steel, contains 13 % chromium and is used for building materials, automobile parts, office equipment, kitchen utensils, and tableware. In general, the strength of STS 410 changes by the carbon content, and STS 410 of low carbon has excellent toughness and high carbon has excellent abrasion resistance. In this study, a fatigue test was performed on the STS 410 material to evaluate the exact fatigue limit and to evaluate the behavior of the material against fatigue. In addition, the effect on burnishing, a kind of plastic processing that creates a smooth surface by pressing a ball or roller on the inner and outer surfaces of the material was evaluated. The fatigue limit was 509 MPa for the STS 410 material, and the result was 54.5 % of the tensile strength. The fatigue limit was 542 MPa for the specimen of diamind burnished STS 410 material, and it was 58.5 % of the tensile strength.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.346-349
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• 2001

Nowadays the amount of plastic products is increasing in modern industry. Plastic materials are continuously developed to satisfy the mechanical, physical, and chemical properties. The increasing application of plastic parts in automobile and aerospace industries is due to the fact that it can reduce the structural weight and can lessen the environmental contamination. Among many manufacturing technologies for plastic parts, the injection molding process is very attractive because of its low cost and short production time. Through various analyses of resin flow and molding process for the conventional gate and cooling mechanism, a new type of mold was designed which had different gate location and cooling systems. Newly designed ball seat has an excellent performances, i.e. diminished weld-line, residual stress density, higher magnitude less crack propagation and smaller dimensional contractions effect.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.40-54
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• 1990

Recently, Fine Ceramics have been concerned significantly with some excellent properties and many functions as new industrial materials to the industry at alrge. For the manufacture of Fine Ceramics, sintering is essential process. Thus the most of a Fine Ceramics used for precision parts are in need of machining proces. It is, however, very difficult to manufacture the Advanced Ceramics with high efficiency because they have not only high strength and brittl- eness but also high hardness. In present research, experiments are carried out to obtain the basic knowledge of Fine Ceramics grinding with high efficiency. Representative advanced ceramics, such as A1/sub 2/0/sub 3/, Z/sub r/O/sub 2/SiC snd Si/sub 2/N/sub 4/are ground with diamond wheels using conventional surface grinding machine. This research is carried out for the purpose of saving machining technology required for manufactiring Fine Ceramics parts

• Transactions of Materials Processing
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• v.17 no.3
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• pp.210-217
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• 2008

The effects of blank shape on the safety of stamped parts are studied through the comparison of an optimal blank and the corresponding reference blank shape to show further advantage of the optimal blank. In order to carry out this study, stamping process has been analyzed and the forming history, e.g. accumulated effective strain and thickness has been incorporated in the crash analysis. The reference blank has been determined following to the actual industry guideline, and excessive material to the desired shape has been trimmed off before crash analysis for the objective comparison. Through the study, appreciable increase of impact safety has not been observed and the effective of blank shape is verified not to be significant.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.244-247
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• 2009

Hydroformed parts have higher dimensional accuracy, structural strength, and dimensional repeatability. Particularly in the automotive industry, manufacturing of parts with complex shapes from tubular materials sometimes requires one or more pre-forming operations such as bending before the hydroforming process. The pre-bending process is an important factor for successful hydroforming in the case where the perimeter of the blank is nearly the same as that of final product. The bendability of a tube depends on the parameters such as the bending radius, variation of the diameter, thickness, hardness. This study shows the analysis of bending through the stainless steel tubes bent to rotary draw bending machine.

• Transactions of Materials Processing
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• v.20 no.4
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• pp.279-283
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• 2011

Recently incremental sheet metal forming (ISF) has used widely in making prototypes and small-volume products in automotive industry etc. We apply the ISF to make a 1/4 sized automobile body-in-white. First, ISF tests for rectangular shaped cup have been performed to clarify the formability denoting the relationship between the component wall angle and maximum cup height of safe forming. Next, a CAD model for the automobile was designed and segmented into several components in order to accommodate the working space of the CNC machine we adopted and the formability of the sheet metal. Then, a CAM software was employed to generate the tool path for manufacturing wooden dies and all the small parts. Finally, the different parts were joined into a single component by laser welding after the ISF process. By using the ISF we successfully produced the 1/4 sized automobile body-in-white.

• Journal of Adhesion and Interface
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• v.21 no.1
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• pp.1-5
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• 2020

Heated tool joining is a popular method for joining parts made from plastics and composite materials. The method is commonly known as butt fusion in the plastic pipe industry and this paper provides a short introduction to the basics of producing a good butt fusion joint. The function of each of the essential parts of the butt fusion equipment is described followed by a presentation of the important parameters of the bonding process in reference to a well-established interfacial pressure versus time curve. The butt fusion procedure is then outlined with good practices that detail the preparation of equipment and pipes to be joined as well as the fusion joining process.

• Journal of muscle and joint health
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• v.21 no.1
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• pp.65-74
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• 2014

Purpose: This study examined gender differences on Musculoskeletal disease (MSD) medical status, the characteristics of the approved patients in workers, and the factors affected approval. Methods: Claim data for the MSD to the Korea Worker's Compensation & Welfare Services (2011) were employed. The medical status by gender was analyzed using t-test, chi square-test and multivariate logistic regression models. Results: The number of claims for MSD has continuously increased in females but not in males since 2006. The severity measured by the care duration, surgery experience and disability grade has been substantially higher in males than in females. Age, size of company, types of occupation, work duration and the weight of materials handled daily were associated with the approval. When males were considered, the work duration, the weight of materials handled daily and parts of the body were statistically significant predictors of approval in males. In case of female, there were meaningful predictors in types of industry and parts of the body. Conclusion: These findings suggest that gender-specific risk factors of MSD should be measured and the management program for MSD should be developed.