• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.05a
• /
• pp.44-48
• /
• 2001

Tube hydroforming technology has increased dramatically, mainly by automotive industry in europe and the americas. It is required tube formability, optimized with regard to tribological factors and specially designed die and presses. In this process has many important parameters as expansion ratio of a tube, axial feeding, internal pressure and preforming low pressure. The following paper discusses to combine forming factors and expectation of manufacture problem by hydroforming of automotive radiator support member.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2006.05a
• /
• pp.403-406
• /
• 2006

Internal spline forming using a thin and long tube can cause the buckling and folding during the forming process. In the study, we proposed two different extrusion processes, and we performed the analysis in order to obtain the optimal process according to the length of land part. Using the rigid-plastic finite element simulation, the proposed processes have been compared by checking the deformed shape and stroke-road relation.

• 유체기계공업학회:학술대회논문집
• /
• 2006.08a
• /
• pp.489-492
• /
• 2006

The present work was performed to investigate the thermal and hydraulic characteristics of flow inside the plain and turbulator flat tubes for the automobile application. The pressure drop and heat transfer coefficient at laminar, transition and turbulent regimes were studied experimentally and numerically. The flow transition was confirmed by flow visualization and quantitative data. It is proposed equations for the friction and heat transfer coefficient in the fully developed laminar flow inside rectangular tube as function of aspect ratio.

• Journal of Haehwa Medicine
• /
• v.25 no.1
• /
• pp.145-153
• /
• 2016

Objectives : The purpose of this study is to evaluate the wound healing potential of Glycyrrhiza uralensis extract. Methods : Free radical scavenging activity tests for DPPH, peroxynitrite (ONOO) and hydroxyl radical (${\cdot}OH$) and total phenolic contents of Glycyrrhiza uralensis extract were conducted. Tube formation assay was performed using human umbilical vein endothelial cells (HUVECs). Results : The results showed that Glycyrrhiza uralensis extract exerted inhibitory effects on ONOO and ${\cdot}OH$. Tube formation in HUVEC was increase in a dose dependent manner. Conclusions : These results show the potential to promote the wound healing process by Glycyrrhiza uralensis extract.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.3
• /
• pp.351-357
• /
• 2012

Small hydropower is a reliable energy technology to be considered for providing clean electricity generation. Producing electrical energy by small hydropower is the most efficient contribution to renewable energy. Cross-flow turbine is adopted primarily because of its simple structure and high possibility of applying to small hydropower. The purpose of this study is to investigate the effect of inlet nozzle shape on the performance and internal flow of a cross-flow turbine for small hydropower by CFD analysis. Moreover, the shape effect of draft tube has been investigated according to modified shapes of the length and the diffuse angle. The results show that relatively narrow and converging inlet nozzle shape gives better effect on the performance of the turbine.

• The Journal of Internal Korean Medicine
• /
• v.25 no.1
• /
• pp.106-118
• /
• 2004

Antigenotoxicity test (SOS chromotest), antimutagenecity test (Ames test), and antioxidant test (NBT method and xanthine-xanthine oxidase method) were carried out using water-soluble and methanolic extracts from Puerariae Flos. Against the mutagens MNNG and NQO, antigenotoxic activity of methanolic extracts were much more effective than that of water-soluble ones. When the methanolic extract was added to the certain concentration $(100{\mu}{\ell}/tube)$, antigenotoxic acivity against the mutagen MNNG was enhanced. Contrary to the water-soluble extract, the methanolic extract showed high antigenotoxicity against the mutagen NQO with increment of the extract. Against the mutagen MNNG with Ames test, antimutagenic activity of the methanolic extract at $300{\mu}{\ell}/tube$ was 96% as an inhibition ratio of revertant forming CFU/plate. The antioxidant activity of water-soluble extract was comparatively higher than that of the methanolic one.

• Journal of Korean Association for Spatial Structures
• /
• v.12 no.4
• /
• pp.81-90
• /
• 2012

The concrete-filled tube (CFT) column has the excellent structural performance. But it is difficult to connect with column and beam because of closed section. Its Solution, 2 members of ㄷchennel in which Internal diaphragm is installed were welded beforehand and the method of making Rectangular Steel Tube was proposed. According to upside and downside junction shape, Internal diaphragm suggested as symmetric specimen and asymmetric specimen. The upper and lower diaphragm of the Symmetric specimen used the same horizontal and The upper diaphragm of the Asymmetric specimen used the horizontal plate and the lower diaphragm used the vertically plate. In this research, 4 T-shape column to beam steps connections were tested with cyclic loading experiment in order to evaluate the structural capability of the offered connection. Symmetric specimens be a failure in 0.03rad from beam flange. And Asymmetric specimens be a failure in 0.05rad from column interface. The comparison results of All specimens shown similar to energy absorption capacity in 0.02rad.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.12
• /
• pp.1748-1755
• /
• 2001

The shell and tube heat exchangers were introduced to apply to a big capacity condenser and a high pressure feed water heater for power plant in the beginning of 1990s. Design and manufacturing technology fur shell and tube heat exchangers have been developed until now. But it is very difficult to calculate the expected performance characteristics of the shell and tube heat exchanger, because there are many design parameters to be considered according to internal structure and the shell side heat transfer mechanism complicately related to the design parameters. Design parameters to be considered in the design stage of shell and tube heat exchanger are shell and tube side fluids, flow rate, inlet and outlet temperature, physical properties, type of heat exchanger, outer diameter, thickness, length of tube, tube arrangement, tube pitch, permissive pressure loss on both sides, type of baffle plate, baffle cutting ratio. The propose of study is an analysis TEMA(Tubular Exchanger Manufacturers Association) E shell and tube heat exchanger performance with changing a number of baffles(3, 5, 7, 9, 11) and tubes(16, 20) and determined optimal baffle spacing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.05a
• /
• pp.324-324
• /
• 2008

• Transactions of Materials Processing
• /
• v.7 no.5
• /
• pp.496-504
• /
• 1998

The eccentric extrusion and bending process for the forming of the curved rectangular hollow tube is newly developed. Generally the bending process of hollow tube is the secondary process followed by the extrusion process of the hollow tube from the round billet. So many defects such as wrinkling and the difference of wall thickness can be happened during the secondary bending process. In order to avoid the defects the new process named as "the eccentric extrusion and bending process" is suggested and applied to the U-bending of rectangular hollow tube. In this paper the kinematically admissible velocity field between the dies surface and the internal plug boundary surface s developed for the curving velocity. By the using of this curving velocity field the curvature of extruded products can be calculated with the parameters such as eccentricity dies length friction constant aspect ratio.