• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.44-49
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• 2006

The use of snap-fit features is highly recommended to reduce overall product cost and manufacturing time by reducing the number of parts and eliminating assembly with conventional fasteners. Application to particular product for integral attachment using snap-fit features is needed. Alternative attachment concept for specific application has been introduced. In this study, the optimal attachment design based on the given design objectives is identified using newly developed alternative attachment concept for the specific application to LCD monitor case assembly. Integral attachment using snap-fit features applies the systematic procedure and the intensity analysis.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.121-126
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• 2006

Snap-fit is being used in manufacture of plastic products. Integral features using snap-fit are classified as locks, locators and enhancements. Locking features complete the process of attachment by providing physical interference to prevent separation. Looking feature pairs consist of two components, i.e., a flexible latch and a rigid catch and require particular care and attention for their selection. We can make several locking feature pairs by selecting latch and catch, but some parts restrict freedom of selection. Therefore, part designers must know the characteristic properties of generic locking feature forms as considering a specific design problem. In this paper, it has been presented about problem of small size products using locking feature and then introduced new locking feature applicable to small parts.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.19-27
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• 2009

Globally, customer appreciation and demand for quieter products has driven noise control engineers to develop efficient and quieter products in a relatively short time. In the vehicles and ship industry, noise has become an important attribute because of the competitive market and increasing customer awareness. Noise reduction is often achieved through structural modifications by typical approaches. In the present paper, author describes a fundamental study on optimum design of curvature. Bezier curve. and rib attachment to reduce noise from simple panel using a genetic algorithm(GA). The acoustic optimization procedure employed p-FEM for structural analysis, the Rayleigh integral method for acoustic analysis and the GA for searching optimum design. In the optimization procedure. the objective function to be minimized is the average sound power radiated from an objective structure over a given frequency range $0{\sim}300$ Hz.

• Plant Journal
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• v.15 no.4
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• pp.43-51
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• 2019

The stress concentration of the integral welded attachments (IWA) often used to support piping system has been a big issue because it induces local stresses in piping. The method to evaluate local stresses associated with attachments on elbows has been suggested in EPRI TR-107453. However, there are limitations regarding specific parameters range in order to use correlation equation. In this paper, parametric study based on piping elbow size and attachment dimension was performed utilizing finite element analysis (FEA) to evaluate the secondary stress indices of hollow circular cross section welded attachments on piping elbows with the extended parameters range. The results of the FEA were used to develop correlation formulas for calculating secondary stress indices. The empirical equations in this study are suggested as an alternative evaluation method of EPRI TR-107453 by extending parameters range.

• Journal of Periodontal and Implant Science
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• v.51 no.4
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• pp.254-263
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• 2021

Purpose: Periodontitis is associated with a dysbiosis of periodontopathic bacteria, which stimulate the interleukin (IL)-23/IL-17 axis that plays an essential role in the immunopathogenesis of this disease, leading to alveolar bone destruction through receptor activator of nuclear factor κB ligand (RANKL). IL-23 receptor mRNA (IL-23R) has been identified in periodontitis, and IL-17 receptor A mRNA (IL-17RA) and its protein have not yet been evaluated in patients with periodontitis. In this study was measure IL-23R and IL-17RA in gingival tissue (GT) from patients with generalized chronic periodontitis (GCP) and generalized aggressive periodontitis (GAP) and to explore correlations with clinical parameters. Methods: We included 16 healthy subjects (HS), 18 patients with GCP, and 14 with GAP. GT samples were collected during periodontal surgery. Both IL-23R and IL-17RA were detected by enzyme-linked immunosorbent assay. Results: The results were analyzed with Mann-Whitney U test and Spearman' rank correlation coefficients using SPSS version 25.0. We found lower IL-23R levels in patients with GCP and GAP than in HS. Contrarily, we observed higher IL-17RA levels in GCP and GAP patients than in HS. Moreover, we found negative correlations between IL-23R in GT and probing depth and clinical attachment loss (CAL). Likewise, a positive correlation of IL-17RA in GT with CAL was found. Conclusions: The results of these findings suggest that the reverse behavior between IL-23R and IL-17RA in periodontitis patients may also be involved with the activation of RANKL, which promotes alveolar bone loss.

• Journal of Mechanical Science and Technology
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• v.19 no.6
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• pp.1347-1357
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• 2005

Effects of combustor-level high free-stream turbulence on the blade-surface heat/mass transfer have been investigated in the three-dimensional flow region near the endwall within a high-turning turbine rotor cascade passage. Free-stream turbulence intensity and integral length scale in the high turbulence case are 14.7 percents and 80 mm, respectively. The result shows that there is no considerable discrepancy in the blade heat/mass transfer near the endwall between the low and high turbulence cases. As departing from the endwall, however, the deviation between the two cases becomes larger, particularly in the region where flow separation and re-attachment occur. Under the high turbulence, flow disturbances such as boundary-layer separation and re-attachment seem to be suppressed, which makes the blade heat/mass transfer more uniform. Moreover, there are some evidences that endwall vortices tend to be weakened under the high turbulence.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.177-180
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• 2009

Tube hydroforming provides a number of advantages over the conventional stamping process, including fewer secondary operations, weight reduction, assembly simplification, adaptability to forming of complex structural components and improved structural strength and stiffness. A hydroformed vehicle body component has an attachment flange or the like-formed as an integral part of the hydroforming process. For a given flange shape, a parting plane for the dies is established relative to which the various surfaces of the flange shape, in cross section, have no significant reverse curvature. This study shows analysis results that form the flanged tubular parts in the hydroforming. The thickness variations and defects during the hydroforming for flange forming could be analyzed by FE analysis. FE analysis was performed by LS-DYNA/Dynaform 5.5.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1435-1450
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• 2004

Experimental data are presented which describe the effects of a combustor-level high free-stream turbulence on the near-wall flow structure and heat/mass transfer on the endwall of a linear high-turning turbine rotor cascade. The end wall flow structure is visualized by employing the partial- and total-coverage oil-film technique, and heat/mass transfer rate is measured by the naphthalene sublimation method. A turbulence generator is designed to provide a highly-turbulent flow which has free-stream turbulence intensity and integral length scale of 14.7% and 80mm, respectively, at the cascade entrance. The surface flow visualizations show that the high free-stream turbulence has little effect on the attachment line, but alters the separation line noticeably. Under high free-stream turbulence, the incoming near-wall flow upstream of the adjacent separation lines collides more obliquely with the suction surface. A weaker lift-up force arising from this more oblique collision results in the narrower suction-side corner vortex area in the high turbulence case. The high free-stream turbulence enhances the heat/mass transfer in the central area of the turbine passage, but only a slight augmentation is found in the end wall regions adjacent to the leading and trailing edges. Therefore, the high free-stream turbulence makes the end wall heat load more uniform. It is also observed that the heat/mass transfers along the locus of the pressure-side leg of the leading-edge horseshoe vortex and along the suction-side corner are influenced most strongly by the high free-stream turbulence. In this study, the end wall surface is classified into seven different regions based on the local heat/mass transfer distribution, and the effects of the high free-stream turbulence on the local heat/mass transfer in each region are discussed in detail.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.227-235
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• 2019

This study monitored Daecheong 1-bo, Daecheong-stream, which carried out the project in 2014, from 2015 to 2016. The technology applied to the stream was evaluated using Periphytic Algae to check contamination indicators and ecological health of the area with an integral river-bed protection using non-toxic materials. The water quality of the monitoring section was confirmed to be above the river environment standard (II), and it was confirmed that the Saproxenic taxa of the river bed protection were higher than the upper and downstream sections. The TDI, which is an index of attachment algae, was shown in the average 51.03 and 52.15 for the pilot project sections in 2015 and 2016, confirming that the index is of the "normal" grade. This is the other sections in the upstream and downstream sections showed higher than "bad", which is thought to have a positive effect on the habitat of the river ecosystem components, especially the microbial population in river bed protection.