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Incheon, South Korea

Kim S.-B.,Naeun Structural Engineering Co. | Kim S.-S.,Korea University of Technology and Education | Shim H.-J.,Hyundai Steel
International Journal of Steel Structures | Year: 2014

Since Euler's classical theory, which he proposed in 1759, many column curve formulations have been proposed. This study investigates the flexural buckling strength (F cr ) calculated using the allowable stress design specification and the load and resistance factor design (LRFD) specification of the American Institute of Steel Construction. It is noted that the exponential function of the column curve formulation using LRFD is difficult to use in practice. Therefore, a simple parabolic function is proposed for the inelastic buckling strength of a steel column loaded with uniaxial compression, and it is shown to be consistent with many design codes. The expressions for inelastic buckling strength formulation as defined previously for ASD are used here. To verify the proposed equation, 118 individual test results of steel columns are examined. The mean of the ratio of the column strength to the proposed flexural buckling strength is 1.089, indicating that the proposed strength curves are in good agreement with the test results. © 2014 Korean Society of Steel Construction and Springer-Verlag Berlin Heidelberg.

Shim H.-J.,Hyundai Steel | Lee E.T.,Chung - Ang University | Kim S.-B.,Naeun Structural Engineering Co. | Kim S.-S.,Korea University of Technology and Education
International Journal of Steel Structures | Year: 2014

This paper reports a new beam-to-column connection that is suitable for use in the weak axis of a column. The proposed system mainly uses bolts, and it minimizes the use of welding, which is generally difficult to perform onsite. In this system, an H-shaped steel beam is joined to an H-shaped steel column by bolted splices at the top flange and without a scallop at the web. Eight specimens were tested to verify the structural performance of the developed connection; in doing so, the effects of geometry and arrangement of the plate were also considered. The connection materials required and CO2 emissions were estimated to evaluate the cost-effectiveness of the proposed system. The obtained results showed that this system was suitable had better structural performance than standard weak-axis connections and excellent constructability, making it suitable for replacing existing bracket-type weak-axis connections. © 2014 Korean Society of Steel Construction and Springer-Verlag Berlin Heidelberg.

Kim H.G.,Hyundai Motor Company | Kim D.H.,Hyundai HYSCO | Lee S.H.,Hyundai Steel | Park S.C.,Hyundai Motor Company
SAE Technical Papers | Year: 2013

The tubular bumper structures, which are a new manufacturing method based on the principle of hot-stamping, structural design, theory of inventive solving problems and test evaluation, represent a new paradigm in vehicle bumper frame construction. This study focused on improvement of stress resistance of steel pipes through advances in materials science and hot-stamping techniques, verification of the formation part and proposed structure by manufacture examination, performance to improve by computer analysis and new vehicle testing methods. As a result of the application, this paper quantifies increases in strength, optimization of structural design and possibility of production for vehicle body. Copyright © 2013 SAE International and Copyright © 2013 TSAE.

Sohn K.,Hyundai Steel | Jeon J.,Hyundai Steel
SAE Technical Papers | Year: 2013

Automakers are putting ever more emphasis on their environmental and energy efficiency efforts through improving the fuel consumption of vehicles. One way of saving energy is to reduce the total weight of the vehicle by using high strength steel. Hyundai steel developed a new 780 MPa grade of hot rolled high strength steel with excellent stretch flange formability in which the ferrite matrix is strengthened by ultra-fine, nano-sized precipitates. The material developed in our study met the material requirement of OEM's material specification with 780 MPa tensile strength and 55% hole extension ratio. Steel grades of 780 MPa were applied to develop front lower control arm for automotive chassis. In order to evaluate the performance of materials, primary design, durability and strength analysis of materials were prepared in collaboration with suppliers. Prototype of front lower control arm was fabricated and durability test and strength test were performed. Both of them satisfied the target. Copyright © 2013 SAE International.

Jung J.,Korea University | Lee J.,Korea University | Lee H.,Hyundai Steel | Ki J.,Hyundai Steel | Hwang J.,Hyundai Steel
Journal of Korean Institute of Metals and Materials | Year: 2012

Water model experiments were carried out to understand the mixing behavior of reducing agents in molten slag through vortex stirrer, which makes use of a gravitational energy to mix reducing agent in the molten slag without imparting artificial energy. At a water flow rate of 6 L/min vortex was not generated, and a stable vortex was formed when the water flow rate was 7 L/min or higher with the present experimental apparatus. Water level increased linearly with increasing the water flow rate. In the upper vortex region, the vertical and horizontal velocities slightly decreased with increasing the water flow rate, whereas those in the lower vortex region increased remarkably. Accordingly, strong mixing behavior was obtained in the lower vortex region. Owing to the strong centrifugal force, particles move downwards with approaching the funnel wall. When 40 grams of polypropylene particles added to the lower vortex, they were instantaneously mixed well.

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