• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.347-357
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• 2013

Recently, In recognition of outstanding structural performance the use of Concrete Filled steel Tube(CFT) columns has been increased. Research is ongoing that effective use of cross-sectional because steel strength development and rising prices. In this Lab, suggests new shape by Thin steel plates bent to be L-channel welded to form square steel tube to maximize efficiency of the cross section. In addition, since the rib placed at the center of the tube width acts as an anchor; higher load capacity of buckling is acceptable. we have developed New shape welded built-up square tube for broader usability which were bent to be L-shaped and thin Plate each unit member were welded. In order to apply the new shape built-up square columns, we predicted structure behavior, stress distribution with parameter Width thickness ratio. The experimental results presented in standards and even exceed the b/t of the rib anchors installed in the role due to exert enough strength and deformation to improve performance was favorable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1571-1578
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• 2015

The cleaning characteristics of pulse air jet type cleaning system which is widely applied in the industries were identified by utilizing the computational fluid dynamics (CFD) and the cleaning performance in modified shape of dedusting unit was compared in this study. The review on each shape of cleaning part showed that the case of installing the nozzle on the blow tube (Case-3) and the case of installing the double intaking tube to the venturi (Case-4 and Case-5) were more excellent than the structure (Case-1). Also, the optimal venturi shape was designed and examined its applicability to the site in a pilot scale plant. A combined system of a blow tube and a venturi proposed by this study turned out to be very effective for concentrating an cleaning air compared to existing systems, such as using only blow tube and combines the blow tube and venturi. In addition, as a result of installing and testing a venturi proposed by this study, the cleaning frequency and cleaning time were much improved compared to a case of using a commercial venturi that is under use at the industrial sites.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.159-165
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• 2003

Self-excited noise generation from laminar flames in thin annular jets of methane/air premixture has been investigated experimentally. Various flames were observed in this flow configuration, including conical shape flames, ring shape flames, steady crown shape flames, and oscillating crown shape flames. Self-excited noise with the total sound pressure level of about 70dB was generated from the oscillating crown shape flames for the equivalence ratio larger than 0.95. Sound pressure and $CH^{\ast}$ chemiluminescence were measured by using a microphone and a photomultiplier tube. The frequency of generated noise was measured as functions of equivalence ratio and premixture velocity. A frequency doubling phenomena have also been observed. The measured $CH^{\ast}$ chemiluminescence data were analyzed from which the corresponding sound pressure has been calculated. By comparing the data with those of measured ones, the noise source can be attributed to the flame front fluctuation near the edge of the oscillating crown-shape flames. The flame stability regime was influenced sensitively to the supplying air through the inner tube.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2085-2090
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• 2007

This paper describes the possible way to improve the capacity, the efficiency and the pressure drop of $CO_2$ system. It is considered the use of an internal heat exchanger (IHX) to improve the performance of the $CO_2$ system. Experiment was performed by changing a tube shape, a tube number and a tube length of IHX to investigate the performance of IHX for $CO_2$ system. The focus of the present study is to obtain the concept on IHX optimal design. Experimental results show that design parameters are closely related with the capacity and the pressure drop of $CO_2$ system. In the transcritical $CO_2$ cycle, the system performance is very sensitive to the IHX design. System performance on operation condition and shape of IHX is also introduced.

• 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.

• Transactions of Materials Processing
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• v.22 no.5
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• pp.275-279
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• 2013

The tube hydroforming process has received much attention in the automotive industry because of its advantages compared to conventional manufacturing technologies. A wide range of products such as sub-frames, camshafts, radiator frames, axles and crankshafts are made by hydroforming process. The hydroformed parts often need to be structurally joined to other components during assembly. Therefore, these automotive parts need to be manufactured with a localized attachment flange. In this study, FE forming analyses of a part with a rectangular flanged shape was performed with Dynaform 5.5. Using the optimized conditions determined numerically, hydroforming experiments were performed. Then, the characterization of defects was analyzed. Finally, the accuracy of the optimized internal pressure condition as well as that of the initial ram position were evaluated. The results demonstrated that flanged parts can be successfully produced using the tube hydroforming process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.241-244
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• 2003

The productivity of hydroforming process can be increased by combining pre-forming process and post-forming process such as the bending, piercing and the embedding process. Therefore in this study, integrated studies on the hydro-embedding technology have been performed by analyzing the deformed mode of the tubes and the optimal process parameters. In the case of the embedding test the characteristics of the embedded parts, such as the shape of the screw tip, screw thread and shape of thread were investigated at various process conditions. To measure the clamping force between the embedded part and the tube, special measuring device was used.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1009-1014
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• 2001

A numerical investigation on nonlinear oscillations of gas in an axisymmetric resonant tube is presented. When a tube is oscillated at a resonant frequency, acoustic variables such as density, velocity, and pressure undergo very large perturbation, often described as nonlinear oscillation. In order to analyze these phenomena, axisymmetric 2-D nonlinear governing equations have been derived and solved numerically. Numerical simulations were accomplished for cylindrical, conical, and 1/2 cosine-shape tubes, which have same volume and length. For conical and 1/2 cosine-shape tubes, very large variation of pressures can be induced without shock formation except the cylindrical tube. In addition, the results well agree to those of 1-D simple model analysis.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.550-555
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• 2009

The present simulation focuses on the effect of the shape of capillary tube-suction line heat exchangers(SLHX), The results in the three cases of the SLHX types show that both of the location and length of heat exchange section influence the coefficient of performance(COP) and cooling capacity. Simulation shows the COP may be improved by 4.6% and the cooling capacity may be improved by 13.6% in the Lateral type.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.31-34
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• 2008

Construction of buildings downtown is increasing as much as ever with a strong demand. A Top-Down Method is suitable for its advantage in minimizing its disturbance to the neighborhood. In general, the Pre-founded Column, one of the most important aspects of the Top-Down Method, has been made with an H-Shape Steel Column. However, due to its structural and economical benefits, the usage of CFT(Concrete Filled Tube) columns in the place of Pre-founded Columns is increasing. To promote their applications, we analyze the merits of CFT columns by comparing them with I-Shape columns and propose further research.