• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.773-777
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• 1995

This thesis attempt to explore the shape of stress wave propagation of 3-dimensional stress field which is made in the process of time increment. A finite element code about 3-dimensional stress wave propagation is developed for investigating the changing shape of the fracture by the impact load. The Finite Element Code, which is the solution for the 3-dimensional stress wave analysis, based on Galerkins and Newmark- .betha. method at time increment step. The tensile stress and compressive stress become larger with the order of the middle, the upper and the opposite layers when the impact load is applied. In a while the shear stress become larger according to the order of the upper, the middle and the opposite layers when impact load applied.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.405-408
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• 2004

The forming load and the stress applied to dies during cold forming of automotive part using microalloyed forging steel are examined with finite element analysis. The forming load and the stress applied to dies at each process step are investigated for two types of forming process. The changes in forming process significantly affect the variation of firming load and the stress at each process step, thus it is considered that the die lift will be remarkably changed with the type of forming process, therefore optimal process design is necessary to obtain an increased the die life and to make the die life uniform at each process step.

• Steel and Composite Structures
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• v.35 no.1
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• pp.1-12
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• 2020

This article deals with the buckling analysis in the plates containing carbon nanotubes (CNTs) subject to axial load. In order to control the plate smartly, a piezoelectric layer covered the plate. The plate is located in elastic medium which is modeled by spring elements. The Mori-Tanaka low is utilized for calculating the equivalent mechanical characteristics of the plate. The structure is modeled by a thick plate and the governing equations are deduced using Hamilton's principle under the assumption of higher-order shear deformation theory (HSDT). The Navier method is applied to obtain the bulking load. The effects of the applied voltage to the smart layer, agglomeration and volume percent of CNT nanoparticles, geometrical parameters and elastic medium of the structure are assessed on the buckling response. It has been demonstrated that by applying a negative voltage, the buckling load is increased significantly.

• Journal of Auto-vehicle Safety Association
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• v.12 no.3
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• pp.27-33
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• 2020

In this paper, the process of predicting efficient durability performance for vibration durability test of automobile parts using vibration test load on automobile fuel tank is presented. First of all, the common standard load that can be applied to the initial development process of the automobile was used for the fuel tank and the vulnerability of the fuel tank to the vibration fatigue load was identified through frequency response analysis. In addition, the vulnerability of the fuel tank was re-enacted through vibration durability test results, and the scale factor was applied to the standard load. In order to predict the vibration durability performance required for detailed design, vibration fatigue analysis was performed on the developed vehicle with the frequency of vibration severity equivalent to the durability test, and the vulnerability and life span of the fuel tank were identified through the process of applying weights to these selected standard loads, thereby reducing the test time of the development vehicle.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1567-1573
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• 2017

The k-nearest neighbor (k-NN) algorithm is one of the most widely used benchmark algorithm in classification. Nowadays it has been further applied to predict time series. However, one of the main concerns of the algorithm applied on short-term electricity load forecasting is high computational burden. In the paper, we propose an approach of dimension reduction that follows the principles of highlighting the temperature effect on electricity load data series. The results show the proposed approach is able to reduce the dimension of the data around 30%. Moreover, with temperature effect highlighting, the approach will contribute to finding similar days accurately, and then raise forecasting accuracy slightly.

• Korean Journal of Materials Research
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• v.9 no.2
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• pp.132-138
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• 1999

In order to investigate the toughening characteristic by microcrack formation in ceramic composites, $Al_2$O$_3$/(0~20)vol% YAG composites containing equiaxed second grains were fabricated using$ Al_2$$O_3$ during hot-pressing. AE(acoustic emission) measurements have been coupled with fracture toughness experiments of SENB method, to evaluate the microcrack formation and the improvement in fracture toughness of ceramic composites. Formation of microcrack was detected by Ae. The generation of AE events increased with increasing of load when load was applied at specimen. The AE events are generated mainly around at maximum load. Specially, the detected AE evetns of composites are many as compared with monolithic $Al_2$$O_3$. Fracture toughness of composites was improved than that of monolithic alumina. $Al_2$O$_3$/YAG composites exhibit main toughening effects by microcracking, results from mutual coalesence of microcracks being generated under applied load. However, there are few toughening mechanism like microcracking in monolithic alumina.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.875-882
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• 2011

In this paper, the finite element analysis model of the mult-axial wheel durability test configuration is created using SAMCEF. Mooney-Rivlin 2nd model is applied to the tire model, and the variation of the air pressure inside the tire is considered. Vertical load, lateral load and camber angle are applied to the simulation model. The tire rotates because of the friction contact with a drum, and reaches its maximum speed of 60 km/h. The dynamics stress results of the simulation and experiment are compared, and the reliability of the simulation model is verified.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.495-502
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• 2010

The effect of load and sliding speed on abrasive wear characteristics of glass fiber/polyurethane (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The friction coefficient, cumulative wear volume and surface roughness of these materials against SiC abrasive paper were determined experimentally. Experimental results showed that the surface roughness of the GF/PUR composites was increased as applied load was higher in wear test. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on applied load and sliding speed for these composites. It could be verified by scanning electric microscopy (SEM) photograph of surface tested that major failure mechanisms were lapping layers, ploughing, delamination, deformation of resin and cracking.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.31-38
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• 1998

Guideway Transportation will provide the break-through to solve the traffic problems, which a lot of big cities have over the world. APM (Automated People Mover) system, Guideway Transportation, is classified by PRT, GRT, and MRT according to the capacity of passenger to be carried by its system. In the Application of PRT (Personal Rapid Transit) system, the enact analysis of the traffic problem on the area to be applied should be preceded. PRT system is characterized by Off-Line and Demand Operation. The Network of PRT system depends on the Load Time and Load Pattern. The operation of PRT system will have move efficient way when it is applied to the network with evenly distributed Load Time and Load Pattern.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.848-853
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• 2004

This is a basic experimental study elaborated on reinforced concrete beam under load, especially crack behavior, bending stiffness, deflection and strain of concrete and reinforced bar for reinforced concrete and steel fiber reinforced concrete beam in relation to fatigue loading in service ability limit states. Test parameters are concrete strength, volume. and type of steel fiber and fatigue loading in service ability limit states to be changed. In order to obtain the actual conditions of various working loads for the aforesaid reinforced concrete beam, minimum load is applied 10$\%$ of maximum design load and maximum load was applied 60$\%$, 80$\%$ and 100$\%$ respectively. Under the same condition, the test was implemented up to 1 million cycle and the result was thoroughly analyzed and reviewed.