• Journal of the Korean Society of Mechanical Technology
• /
• v.13 no.4
• /
• pp.49-55
• /
• 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.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.9
• /
• pp.48-56
• /
• 2021

Tungsten carbide (WC) circular saws have been widely used to cut plywood. Recently, expensive polycrystalline diamond (PCD) were adopted to extend the tool life of circular saws. This study developed a PCD-WC combination circular saw and compared its performance with that of existing WC and PCD saws. Flank wear of WC saw blades and edge chipping of rectangular PCD was observed during the experiments. The PCD-WC saw replaced half of the chamfered teeth with PCD and applied tough WC for all rectangular teeth. In the experiments, edge chipping was not observed in rectangular WC teeth and the flank wear of chamfered teeth was decreased compared with that of conventional circular saws.

• Journal of Korean Elementary Science Education
• /
• v.30 no.1
• /
• pp.71-82
• /
• 2011

The purpose of this study was to evaluate the change of chemistry-related attitude of preliminary teachers, after the project of examining chemists contributing to the quality of human life. One group pretest-posttest was used in this study as an experimental design. Before examining the chemist, few preliminary teachers have the knowledge about the chemist contributing to the quality of human life. After the project of examining the chemist, the affirmative awareness on the chemist on preliminary teachers is increased. This result shows that the project of examining the chemist contributing to quality of life can give to make the positive attitude of preliminary teachers on chemistry, and to apply the useful tool related to STS curriculum which is not described effectively in science or chemistry textbook.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1997.10a
• /
• pp.265-270
• /
• 1997

Helical gear system is utilized to transmit motion between parallel shafts. The axial thrust loads on the shafts are existed. On each of the support shafts, at least one of the bearings should be able to support the axial loads. The reliability and life analysis are based on the two-parameter Weibull distribution lives of the component gears and bearings. The computer calculates the system lives and dynamic capacities of the components and their system. The system life is defined as the life of the component or the helical gear system at an output torque at which the probability of survival is ninety percent.

• Transactions of Materials Processing
• /
• v.12 no.4
• /
• pp.408-413
• /
• 2003

Dies may have to be replaced for a number of reasons, such as changes in dimensions due to die wear or plastic deformation, deterioration of the surface finish, break down of lubrication and cracking or breakage. In this paper, die cooling methods have been suggested to improve die service life considering die wear and plastic deformation in hot forging process. The yield strength of die decreases at higher temperatures and is dependent on hardness. Also, to evaluate die life due to wear, modified Archard's wear model has been proposed by considering the thermal softening of die expressed in terms of the main tempering curve. It was found that the use of die with cooling hole was more effective than that of direct cooling method to increase the die service life for spindle component.

• Journal of the Korean Society of Safety
• /
• v.17 no.2
• /
• pp.63-68
• /
• 2002

Life Cycle Cost analysis technique is introduced to evaluate cost-effectiveness of two paint systems of steel bridges. The systems are a conventional paint system and a galvanized paint system. The all costs during safe lift such as initial cost repainting costs, disposal costs are considered for the lift cycle cost analysis. The NIST model is used and BridgeLCC 1.0 developed by the NST is utilized as the lift cycle cost analysis tool. It is concluded that, in spite of expensive initial cost, the durable paint system may be cost-effective compared with conventional paint system.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.3
• /
• pp.558-562
• /
• 2010

SDS-PAGE of extracted surface-associated proteins of Lactobacillus rhamnosus strains E/N, Oxy, and Pen, was performed. The obtained protein patterns allowed differentiation of the examined strains, which was not accomplished by the commonly used RAPD genotypic method. The differentiation by the SDS-PAGE method proved to be a useful tool for strain-specific identification, which was further confirmed by 2DE analysis. Therefore, it can be used as an alternative or complementary method for both conventional and genotypic identification procedures, especially when closely related lactobacilli isolates are identified.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1998.06b
• /
• pp.54-59
• /
• 1998

In this study, two kinds of life prediction method for hot forming die are developed . One is empirical method requiring some experiment that evaluate thermal softening of die material accoring to operating conditions. The other is analyticl method that calcuate wear quantity of die occuring during the forming process. Wear is a predominant factor as well as plastic deformation and heat checking . And, these methods are applied to prodict tool life real die producting part for automobile. Thus , the applicability and the accuracy of the presented methods are investigated. Using the verified life prediction method above , optimal blocker die design minimizing the finisher die is done.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.479-484
• /
• 2004

For the rational design of welded joint, it is needed to assess repeatedly the fatigue life of the joint with various dimensions and welding conditions. In this paper, an automation of repeated process of fatigue life assessment for welded cruciform joint was studied. The process is related to stress analysis in vicinity of weld-toe and fatigue life assessment based on analyzed stress distribution. With the change of design condition including dimensions and/or welding heat input, the above two works have to be performed. Using the commercial tool for system integration, ModelCenter, an automation of the repeated process for welded cruciform joint based on 2D modeling was achieved. In this automation system, data exchanges between programs regardless of commercial or in-house one work well, and parametric studies for optimal design can be performed.

• International journal of advanced smart convergence
• /
• v.10 no.1
• /
• pp.125-133
• /
• 2021

The purpose of this study is to investigate the effect of the elderly's motivation to participate in ball games In order to clarify the purpose of this study, leisure sports participants over the age of 20 residing in the Jeonnam region in 2020 were selected as the population. In addition, 150 males, 150 females, and 300 total subjects were selected using the convenient sampling method. In addition, as a survey tool, a questionnaire was used centering on the motivation for participation in leisure sports, exercise commitment, and quality of life, and the data collected using this was processed statistically according to the purpose of analysis using SPSS 20.0 version. The results obtained through this research process are as follows. First, it was found that the motivation to participate in leisure sports has a partial effect on exercise commitment. Second, it was found that the motivation to participate in leisure sports partially affects the quality of life. Third, it was found that the commitment to exercise in leisure sports has a partial effect on the quality of life.