• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.298-307
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• 2006

TEE Forming process for HDPE(High Density PolyEthylen) pipe has been analyzed by using rigid plastic finite element code, DEFORM-3D. TEE of HDPE pipes is necessary to connect main pipe with branch pipe and change the flow direction of hot water. A HDPE pipe is used as a insulator to maintain the temperature of hot water A butt welding process through TEE forming for a HDPE pipe is a updated process improving the strength of welding part compared to conventional extrusion welding process. The Experiment of Hot and Cold Forming have been performed. The design parameters such as a initial hole shape have been obtained through rigid-plastic finite element analysis, which is applied to the actual manufacturing process.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.230-235
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• 2000

By using the finite element method, the Oyane's ductile fracture integral I was calculated from the histories of stress and strain according to every element and then the forming limit of hydroforming process could be evaluated. The fracture initiation site and the forming limit fer two typical hydroforming processes, tee extrusion and bumper rail under different forming conditions are predicted in this study. For tee extrusion hydroforming process, the pressure level has significant influence on the forming limit. When the expansion area is backed by a supporter and bulged, the process would be more stable and the possibility of bursting failure is reduced. For bumper rail, the ductile fracture integral I is not only affected by the process parameters, but also by the shape of preforming blank. Due to no axial feeding on the end side of the blank, the possibility of cracking in hydroforming of the bumper rail is influenced by the friction condition more strongly than that of the tee extrusion. All the simulation results show reasonable plastic deformation, and the applications of the method could be extended to a wide range of hydroforming processes.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.22-28
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• 2000

By using the finite element method, the Oyane's ductile fracture integral I was calculated from the histories of stress and strain according to every element and then the forming limit of hydroforming process could be evaluated. The fracture initiation site and the forming limit for two typical hydroforming processes, tee extrusion and bumper rail under different forming conditions are predicted in this study. For tee extrusion hydroforming process, the pressure level has significant influence on the forming limit. When the expansion area is backed by a supporter and bulged, the process would be more stable and the possibility of bursting failure is reduced. For bumper rail, the ductile fracture integral i is not only affected by the process parameters, but also by the shape of preforming blank. Due to no axial feeding on the end side of the blank, the possibility of cracking in hydroforming of the bumper rail is influenced by the friction condition more strongly than that of the tee extrusion. All the simulation results show reasonable plastic deformation, and the applications of the method could be extended to a wide range of hydroforming processes.

• Transactions of Materials Processing
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• v.26 no.5
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• pp.271-276
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• 2017

A tee is the most common pipefitting used to combine or divide fluid flow. Tees can connect pipes of different diameters or change the direction of a pipe run. To manufacture tee type of stainless steel pipe, combinations of punch piercing and burr forming have been widely used in the industry. However, such method is considerably time consuming with regard to performing empirical work necessary to attain process conditions to prevent upper end tearing of the tee product and meet target tee height. Numerous experiments have shown that the piercing profile is the main cause of defects mentioned above. Furthermore, the mold design is formed through trial and error according to pipe diameters and changes in requirements. Thus, the objective of this study was to perform piercing and burring process analysis via finite element analysis using DYNAFORM to resolve problems mentioned above. An optimization design method was used to determine the piercing punch profile. Three radii of the piercing punch (i.e., large, small, and joined radii) were selected as design variables to minimize thinning of a tee pipe. Based on results of correlation and multiple regression analyses, we developed a predictive approximation model to satisfy requirements for both thickness reduction and target height. The new piercing punch profile was then applied to actual tee forming using the developed prediction equation. Model results were found to be in good agreement with experimental results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.11
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• pp.781-787
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• 2010

To improve the efficiency of piping, recently the pre-fabrication piping system has been introduced, and much attention has been paid to TBPs which can replace Tee-joint. Forming and forming analysis on TBPs made from Carbon steel pipes for pressure service(KS D 3562 Sch40) and Stainless steel pipes(KS D 3576 20S) have been conducted to determine working pressure. Forming and forming analysis objects are $32A{\times}25A$, $40A{\times}25A$, $40A{\times}32A$, $50A{\times}25A$, $50A{\times}32A$, $50A{\times}40A$ TBPs.

• Transactions of Materials Processing
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• v.11 no.1
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• pp.54-60
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• 2002

The purpose of the present paper is to investigate the effect of Process parameters such as internal pressure, amount of axial feeding, and frictional condition between the die and the material on the tube hydro-formability. For carbon steel tubes(STKM 12A, STBH 410 and SPS 290), simple bulging, circular bulging and Tee-fitting tests are performed to evaluate the hydro-formability of these materials which is determined by deformation characteristics such as thickness distribution, forming height and branch dome shape. The formabilities obtained from these tests are analysed and compared with the results of the numerical simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.49-53
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• 2001

Recently hydroforming process became a process which is increasingly applied in the automotive industry. As the hydroforming process is a new technology, there is no abundant data to assist manufacturing the products. To investigate the effects of process parameters on the tube hydroforming process, simple bulging, circular bulging and Tee-fitting tests are performed. The optimal leading path to escape the failure modes(bursting, wrinkling) is determined and the effects of the process parameters, the internal pressure and axial feeding on the product quality, such as thickness distribution, forming height and branch dome shape are investigated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.36-39
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• 2001

Tubular hydroforming has attracted increased attention in the automotive industry recently. In this study, a professional finite element program for analysis and design of tube hydroforming processes has been developed, called HydroFORM-3D, which is based on a rigid-plastic model. With the developed program several hydroforming processes such as a tee extrusion, an automotive rear axle housing and lower arm are analyzed and designed. And also, the Oyane's ductile fracture integral I was calculated from the histories of stress and strain according to every element and then the forming limit of the hydroforming process could be evaluated. The pediction of the bursting failure and the plastic deformation during typical hydroforming processes shows to be reasonable so that this approach can be extended to other various tube hydroforming processes.

• Journal of the Korean Institute of Landscape Architecture
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• v.21 no.1
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• pp.13-30
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• 1993

The purpose of this study was to present data to the landscape planning and design through analyzing correlation between visual preference of users and nonusers and the landscape of hole in golf couses. Stimulus objects were selected from the 18 holes in Tae-gu Country Club. Preference value was judged through photo simulation by 35 subjects photographed at Tee and Interpoint (IPI, IP2), and classified into three landscape types and nine landscape components from photo analysis by researcher. For test of difference between groups toward each stimulus, t-test was used, and Duncantest, Correlation analysis for finding out correlation between preference degree and the landscape of each hole. The results of this study were as follows: As a result of analysis of preference value between groups for each hole, it has been shown that there was scarcely difference with each other. Form the relation between preference degree and spacial structure of hole, the holes making up a superior preference group have been shown that the greater part of the holes had a downward slope or a gentle slope mostly and then a visible ratio of fairway was high, and had diversified scenery by a lotus pond, a solitary planting tree, the roll of a fairway, facilities for convenience, etc. The holes making up a low-ranking preference group have been shown that the greater part of the holes had upward slope or a similar slope to it and had characteries of the bad condition of lawn, the nearby factories and odors, the monotonous scenery of a fairway, an unreasonable mixing of holes, etc. From the relation between preference degree and landscape components forming hole, it has been shown that the preference degree between users and nonusers had positive correlation to the occupied ratio of space of landscape components at Tee and Approach. At Tee, it has been shown that the preference degree of two groups were related with a lawn surface of fairway negatively, a lotus pond, a sky positively, and the preference degree of nonusers was related with iron-top for electric transmission positively. At Approach, it has been shown that the preference degree of two groups were related with iron-top for electric transmission negatively, and the preference degree of nonusers was related with a building positively. From the relation between preference degree group to each hole and the occupied ratio of space of landscape types, it has been shown that the constituent ratio of a high-ranking group was 1:2.4:2.2 and a low-ranking group was 1:4.1:5.1 among vertical type, horizontal type and background at Tee, but the constituent ratio of space of a high-ranking group was similar to a low-ranking group at Approach.

• Journal of Korean society of Dental Hygiene
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• v.17 no.4
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• pp.613-620
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• 2017

Objectives: The purpose of this study is to investigate the antibacterial effect of Streptococcus mutans of tea tree ingredient. Methods: The experimental groups were each given with different concentrations (30 or 50 vol%) of tea tree prepared in saline solution. The control group applied only saline solution. The tea tree coating of the specimen were examined under a scanning electron microscope. For the antibacterial activity test of the tea tree, the contact angle of the tea tree- coated specimen's surface was analyzed. The antibacterial effect against Streptococcus mutans was determined by counting the colony forming units (CFU). The statical statics were evaluated by using one-way ANOVA and paired t-test. Results: The tea tree treated group of hydrophilic more than non treated group. Antibacterial experiments demonstrated that tee tree solution was effective against Streptococcus mutans. However there was no significant difference in depending solution concentration groups. Conclusions: The antimicrobial activity of the tea tree containing solution showed its potential for use as coating for denture and medical materials.