• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.1051-1054
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• 2005

On this study, we optimized minimizing the characteristic function for mixed result of the structural contact analysis and the buckling analysis according to the pin jig initial model's level change using mixed the table of orthogonal away and ANOM, Pin jig's weight is reduced up to 20 percent considering constraint conditions. Also we optimized reducing 20 percent weight of pin jig model using topology optimization.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.98-104
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• 2018

Deflected 4-way panels of ceiling air conditioners produced by injection molding process have caused dew condensation at the edge of products. In order to prevent this drawback with reducing weight and deformation, this study proposed renovated process adopting microcellular foaming. According to results from 2-sample t-test and analysis of variance(ANOVA), the critical factors affecting weight were melt temperature and injection speed. In addition, the vital effects on deformation were structure at the edge, mold temperature and cooling time. Optimal conditions of these parameters were derived by regressive analysis with CAE and response surface method(RSM), and then applied to an actual design and process stage to analyze performance. As a results, it clearly showed that new process improved process capability as well as reduced both weight and deformation by 18.8% and 71.9% respectively compared to the conventional method.

• Journal of Institute of Convergence Technology
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• v.12 no.1
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• pp.31-35
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• 2022

This study has been carried out in order to improve the rolling problem by enhancing steering stability compared to the 2021 Student Car of the KNUT_EV team for KSAE. Among the various factors affecting steering performances, it was focused on the height of the centroid of weight, the motion ratio, and the spring deflection. In the 2022 Car, a pull rod suspension was used to reduce the height of the centroid of weight and designed with a structure of the rod and rocker to satisfy the target motion ratio. The spring deflection was testified by ADAMS and ABAQUS analysis, and the spring stiffness was selected at 350lb/inch and 450lb/inch for the front and rear wheels, respectively. As a result, the rolling angle of the 2022 Car was reduced compared to the 2021 Car, and the rolling phenomenon was improved.

• Computers and Concrete
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• v.29 no.6
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• pp.361-374
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• 2022

On the premise of ensuring that the automatic and quantitative discharging function of concrete conveyors is met, the accuracy of the weight forecast by the mathematical model of the screw conveying volume is improved, and the error of the weight of the concrete parts and the accumulation thickness is reduced. In this paper, the discrete element method (DEM) is used to simulate the macroscopic flow of concrete. Using the concrete discrete element model, the size of the screw conveyor is set, and establish the response model between the influencing factors (process and structure) and the concrete mass flow rate according to the design points of the screw discharging experiment. The nonlinear data fitting method is used to obtain the volumetric efficiency function under the influence of process and structural factors, and the traditional screw conveying volume model is improved. The mass flow rate of concrete predicted by the improved mathematical model of screw conveying volume is consistent with the test results. The model can accurately describe the conveying process of concrete and achieve the purpose of improving the accuracy of forecasting the weight of discharged concrete.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1099-1107
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• 2013

This study proposes a weight reduction design for urban transit, specifically, a Korean EMU carbody made of aluminum extrusion profiles, according to size optimization and useful material changes. First, the thickness of the under-frame, side-panels, and end-panels were optimized by the size optimization process, and then, the weight of the Korean EMU carbody could be reduced to approximately 14.8%. Second, the under-frame of the optimized carbody was substituted with a frame-type structure made of SMA 570, and then, the weight of the hybrid-type carbody was 3.8% lighter than that of the initial K-EMU. Finally, the under-frame and the roof-panel were substituted with a composite material sandwich to obtain an ultralight hybrid-type carbody. The weight of the ultralight hybrid-type carbody was 30% lighter than that of the initial K-EMU. All the resulting carbody models satisfied the design regulations of the domestic Performance Test Standard for Electrical Multiple Unit.

• Fire Science and Engineering
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• v.25 no.4
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• pp.22-27
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• 2011

Fire resistance ceiling system is the structure of which the ceiling installed under the slave of the structure has the fire resistance performance. Because of having the fire resistance performance, fire resistive coatings on steel beams can be reduced and large span structures can be constructed. So, it have advantages of convenience for construction, shorten for construction time and cost reducing. In foreign country, it is general that one system consisting of slave and ceiling is constructed as a fire resistance system. But in Korea, there are no fire resistance ceiling systems thus economical efficiency due to being high-rise and light-weight of structures is not secured. Therefore research and development of nominal fire resistance ceiling systems is necessary. On this study, fire resistances of standard non-loadbearing ceiling systems were assessed and basic informations for developing the fire resistance non-loadbearing ceiling systems were presented.

• Composites Research
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• v.32 no.1
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• pp.45-49
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• 2019

Fiber reinforced composites fabricated by the resin film infusion (RFI) process, which is one of the outof-autoclave process, have the advantage of significantly reducing the processing cost in large structures while having excellent mechanical properties and uniform impregnation of the resin. In this study, we applied RFI carbon fiber composites to unmanned aerial vehicle structures to improve structural safety and achieve weight reduction. The tensile test results showed that the strength was 46% higher than that of generic T300 grade plain weave carbon fiber composites. As a result of the layup design and finite element analysis of the composite wing structure using the above material properties, the wing tip deflection is decreased by 31%, the structural safety factor is increased by 28% and the weight of the entire structure can be reduced by more than 10% compared to the reference model using glass fiber composite material.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.353-364
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• 1998

This paper describes the design processes and evaluation results of a small-sized six-axis force/torque sensor. The new six-axis force/torque sensor including S-type structure has been developed using a parallel plate structure as a basic sensing element. In order tominimize coupling errors, the location of strain gages has been determined based on the finite element analysis and the connections of strain gages have been made such that the bridge circuit with 4 strain gages becomes balanced. Several design modifications result in a similar strain sensitivity for six-axis forces and moments, and the reduced coupling errors of 2.6% FS between each forces and moments. Calibration test results show that the six-axis load cell developed which has light weight of 135g and the maximum capacities of 196 N in forces and 19.6 N.m in moments is estimated to be within 7.1% FS in coupling error.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.76-83
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• 2010

Metallic sandwich panels with pyramidal truss structures are high-stiffness and high-strength materials with low weight. In particular, bulk structures have enough space for additional multi-functionalities. In this work, in order to fabricate 3-D structures efficiently, Layered Manufacturing Method (LMM) which was composed of three steps, including crimping process, stacking process and bonding process using rapid infrared brazing, was proposed. The joining time was drastically reduced by employing infrared brazing of which heating rate and cooling rate were faster than those of conventional furnace brazing. By controlling the initial cooling rate slowly, the bonding strength was improved up to the level of strength by conventional vacuum brazing. The observation of infrared brazed specimens by optical microscope and SEM showed no defect on the joining sections. The experiments of 1-layered pyramidal structures and 2-layered pyramidal structures subject to 3-point bending were conducted to determine structural advantages of multilayered structures. From the results, the multi-layered structure has superior mechanical properties to the single-layered structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.332-335
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• 2014

Applying damping sheets or dampers (dynamic or mass) can reduce noise from vibrating structure as well as vibration. However, this approach requires increases of weight and cost. If one can reduce structural noise by only modifying the structural shape, which would be the best practice. It is natural that the noise characteristics change when the structure is modified, but the recent experiment on the sunroof frame showed that the modification of the frame beads results in change of the structural damping, so that the corresponding noise can be reduced. In this context, the reason why the structural damping and the related noise upon an impact excitation is changed is theoretically investigated. The change of dynamic and damping characteristics of the strip panels when their shapes are modified is experimentally found and it is shown that such behaviours can be predicted by computer simulation. Some experimental specimen, mainly strip-type panels, are examined for the numerical verification, and especially damping ratios are investigated.