• Transactions of Materials Processing
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• v.16 no.3 s.93
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• pp.201-209
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• 2007

Generally, the forming process of suspension system parts have been considered only considered with the formability and have not been considered with the durability of suspension system. But the durability of suspension system is very important characteristic for the dynamic performance of vehicle. Therefore, the suspension system should be manufactured to consider the durability as well as the formability. This paper is about an optimum forming process design with the effect of section properties to consider the roll durability of torsion beam type suspension. In order to determine the tube hydroforming process for the satisfaction the roll durability, the stamping and hydroforming simulation by finite element method were performed. And the results from finite element analysis and roll durability examination showed the tube hydroforming process of torsion beam is optimized as satisfying the durability performance.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.113-119
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• 2010

Hydroforming is the technology that utilizes hydraulic pressure to form tube or sheet materials into desired shapes inside die cavities. 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. In many case, hydroformed parts have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. In this study for the numerical process design FE analysis was performed with DYNAFORM 5.5. Die parting angle and circumferential expansion ratio was optimized. With optimized condition, bulge and hydroforming experiments to form flange were performed. Forming characteristic at various pressure conditions was analyzed and optimized internal pressure condition was evaluated. The results show that flanged parts can be successfully produced by tube hydroforming process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.483-490
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• 2013

In aluminum sheet metal forming, the conventional forming methods of T4 or T6 heat-treated sheets result in low formability and dimensional accuracy. This study suggests a new forming method for aluminum sheets called as hot forming quenching (HFQ) that solves the problems faced in the conventional method. HFQ combines the heat treatment and forming processes through the forming die during the quenching of a solid solution. To evaluate the application of HFQ to the sheet forming of aluminum, an Erichsen and V-bending test are performed in this study to measure the dimensional accuracy and formability, which are then compared with those of the conventional forming method. Furthermore, the strength and hardness of the products formed by HFQ are measured to confirm the degradation in mechanical properties compared with the conventional forming method, which shows the validity of the application of HFQ to aluminum sheet metal forming.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.322-325
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• 2007

Dent resistance is an important characteristic to avoid damage on automotive outer panels. From a practical point of view, dents can be caused in a number of ways. Considering doors as an example, denting can occur from stone impacts or from the careless opening of an adjacently parked vehicle door. Denting can occur where the door surface is smooth and may not have sufficient curvature to resist dent. These exterior body parts are designed to improve dent resistance using a combination of work hardening and bake hardening. In brief, dent is affected by the shape of the parts and the material properties such as yield strength, strain and thickness. In this work, forming of door outer panel is investigated by Taguchi method. Main parameters are yield strength, thickness, blank size, blank holding force and so on. For the given value of design parameters, forming analysis of the thirty six cases are carried out according to L18 orthogonal array. After comparing the performance by simple conversion of simulation results into dent resistance, the final suggestion of the forming parameters is verified for the best improvement of dent resistance.

• Journal of the korean society of oceanography
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• v.34 no.4
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• pp.214-219
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• 1999

Cells of the dinoflagellate Gyrodinium impudicum form characteristic chains, which are associated with sugar accumulated on the cell surface. To resolve the relationship between chain-formation and cell surface sugar accumulation, confocal microscopy was used to observe sugar accumulation points in the vegetative cells and long chain-forming cells of G. impudicum cells treated with fluorescent-tagged ConA. In the stationary and exponential phases, both vegetative cells and chain-forming cells were similar to each other in fluorescent intensity. There was no evidence that chain-forming cells had a specific location for sugar accumulation on the cell surface. Most of the cells formed 2-cell chains one day after inoculation, but longer chains consisting of 4-8 cells increased markedly in 4day and 8 day cultures. Gyrodinium impudicum chains usually consist of more than four cells, and chains of 8 or even 16 cells can be observed in mature cultures. Temperature played an importantrole in chain-formation of the cells, threshold temperature for the development of long chain-formation was 19 $^{\circ}$C.

• Transactions of Materials Processing
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• v.25 no.4
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• pp.268-274
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• 2016

In the automotive seat industry, the use of a fine blanking press is important for manufacturing of high precision products. Among them, a gear part which is a main component of an automotive seat recliner is generally manufactured by fine blanking press. However, the use of conventional mechanical press has been increasing in manufacture of gear part because of low productivity of fine blanking press. In this study, new forming process is suggested to fabricate the gear part with high precision by using mechanical press. The effect of flow restriction die (FRD) which has the restriction of blank edge on dimensional accuracy is investigated by FE-analysis. FE-analysis results for different conditions of FRD indicated that FRD has high dimensional accuracy with the lowest roll-over and the highest perpendicularity of gear part. After application to fabrication of the gear part using mechanical press, the measured dimensional characteristic was compared with the required specification of final product. In addition, results of the performance test showed that the product fabricated by developed process satisfied the required strength and durability. The results show that the suggested forming process by using FRD and mechanical press can replace fine blanking on the viewpoint of dimensional accuracy and productivity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.1069-1076
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• 2014

This paper presents an efficient receive beam structure able to search and track the simultaneous bundle targets with the active electrically scanned array radar. One of the characteristic with the active phased array radar is to point toward wanted direction and to forming simultaneously the digital multi-beam. This paper proposes method to detect and track rapidly bundle targets coming to radar using the digital beam forming. The proposed the beam forming method in the paper is evaluated about the angle accuracy of targets via a computer simulation.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.589-590
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• 2006

Based on the comparison of structures and properties of the HS6-5-2 high speed steels made with the powder injection moulding method, pressureless forming, compacting and sintering, and commercial steels made with the ASEA-STORA method, fine carbides spread evenly in the steel matrix were found in the structure of all tested high-speed steels in the sintered state. The steels made with the pressureless forming method are characteristic of the lowest sintering temperature and the highest density, resulting from the high carbon concentration coming from the binding agent degradation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.46-53
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• 2022

This paper presents the design and manufacture of a Solid State Relay (SSR) life prediction device that can predict the lifetime of an SSR, which is a key component of a glass forming machine. The lifetime of an SSR is over when the current supplied to the relay is overcurrent (20 A or higher), and the operating time is 100,000 h or longer. Therefore, the life prediction device for the SSR was designed using DSP to accurately read the current and temperature values from the current and temperature sensors, respectively. The characteristic test of the manufactured non-contact relay life prediction device confirmed that the current and temperature were safely measured. Thus, the SSR lifetime prediction device developed in this study can be used to predict the lifetime of an SSR attached to a glass forming machine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.173-174
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• 2012