• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.351-358
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• 2013

In the electric power supplying industry, outdoor sealing end (pothead) is used and sometimes it is necessary to check the seismic qualification analysis or test which is intended to demonstrate that the equipment have adequate integrity to withstand stress of the specified seismic event and still performs their function. And since the pothead is mounted on the supporting jig, the avoidance of resonance between the pothead and jig is required. In order to design jig, three types of optimization are performed to get the minimum weight while satisfying the natural frequency constraint using ANSYS. Optimal array, position and thickness of truss members of the jig are obtained through topology, shape and sizing optimization process, respectively. And seismic analysis of the pothead on the jig for given RRS acceleration computes the displacement and stress of the pothead which shows the safety of the pothead. The obtained natural frequency, mass, and member thickness of the jig are compared with those of the reference jig which was used for seismic experimental test. The numerical results of the jig in the research is more optimized than the jig used in the experimental test.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.22-28
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• 2015

The primary design goal of a compressor is focused on improving efficiency. Secondary objective is to widen the operating range of compressor. This paper presents a numerical and experimental investigation of the influence of the bleed slot on the operating range for the 1.2 MW class centrifugal compressor installed in a turbocharger. The main design parameters of the bleed slot casing are upstream slot position, inlet pipe slope, downstream slot position and width. The DOE(design of experiment) method was carried out to optimize the casing design. Numerical analyses were done by the commercial code ANSYS-CFX based on the three dimensional Reynolds-averaged Navier-Stokes equations. Results showed that efficiency and pressure ratio increased as the downstream slot position and width were smaller and the upstream position was located away from the impeller inlet. Experimental works were also done with and without the bleed slot casing. The simulation results were in good agreement with the test data. Enhancement of both the surge margin up to 26.5% and the pressure ratio with the optimized bleed slot design were achieved, compared with the surge margin of only 6.6% without the bleed slot casing.

• International Journal of Fluid Machinery and Systems
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• v.3 no.4
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• pp.315-323
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• 2010

This work investigates the influence of water compressibility on pressure pulsations induced by rotor-stator interaction (RSI) in hydraulic machinery, using the commercial CFD solver ANSYS-CFX. A pipe flow example with harmonic velocity excitation at the inlet plane is simulated using different grid densities and time step sizes. Results are compared with a validated code for hydraulic networks (SIMSEN). Subsequently, the solution procedure is applied to a simplified 2.5-dimensional pump-turbine configuration in prototype with different speeds of sound as well as in model scale with an adapted speed of sound. Pressure fluctuations are compared with numerical and experimental data based on prototype scale. The good agreement indicates that the scaling of acoustic effects with an adapted speed of sound works well. With respect to pressure fluctuation amplitudes along the centerline of runner channels, incompressible solutions exhibit a linear decrease while compressible solutions exhibit sinusoidal distributions with maximum values at half the channel length, coinciding with analytical solutions of one-dimensional acoustics. Furthermore, in compressible simulation the amplification of pressure fluctuations is observed from the inlet of stay vane channels to the spiral case wall. Finally, the procedure is applied to a three-dimensional pump configuration in model scale with adapted speed of sound. Normalized Pressure fluctuations are compared with results from prototype measurements. Compared to incompressible computations, compressible simulations provide similar pressure fluctuations in vaneless space, but pressure fluctuations in spiral case and penstock may be much higher.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.4
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• pp.350-357
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• 2016

In this paper, a small mu-zero zeroth order resonance(ZOR) antenna based on meta structure is proposed using parasitic patch at 5.8 GHz. The mu-zero ZOR antenna is designed by utilizing the resonance of series inductance and capacitance of mu-negative transmission line and its size can be further reduced by a simple parasitic patch. The parasitic patch can increase series capacitance of mu-negative transmission line related to a resonant frequency. We have simulated and optimized dimension of the parasitic patch using Ansys commercial simulator(HFSS). As a result, the antenna has the following characteristics: kr of 0.59, efficiency of 92 %, and gain of 6.57 dBi. Also, its size is reduced by 24 % compared to a conventional mu-zero ZOR antenna. The measured results are in good agreement with the simulated results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.285-291
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• 2017

In this study, a case analysis for thermal design of electronic equipment using a phase change material(PCM) was performed numerically using ANSYS Fluent. Experiments were conducted to find the temperature increase(${\Delta}T_m$), melting temperature($T_m$), and volume expansion of the PCM under the melting process. To verify the accuracy of the Fluent solver model, $T_m$, ${\Delta}T_m$, and the melting time were compared with experimental results. To simulate the temperature stagnation phenomenon under the melting process, the equivalent specific heat method was applied to calculate the thermal properties of the PCM in the solver model. To determine the thermal stability of electronic equipment, we paid special attention to finding a thermal design for the PCM using fins. Further, an additional numerical analysis is currently underway to find an optimum design.

• Biomaterials and Biomechanics in Bioengineering
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• v.3 no.2
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• pp.115-127
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• 2016

Shoulder pain, injury and discomfort are public health and economic issues world-wide. The function of these joints and the stresses developed during their movement is a major concern to the orthopedic surgeon to study precisely the injury mechanisms and thereby analyze the post-operative progress of the injury. Shoulder is one of the most critical joints in the human anatomy with maximum degrees of freedom. It mainly consists of the clavicle, scapula and humerus; the articulations linking them; and the muscles that move them. In order to understand the behavior of individual muscle during abduction arm movement, an attempt has been made to analyze the stresses developed in the shoulder muscles during abduction arm movement during the full range of motion by using the 3D FEM model. 3D scanning (ATOS III scanner) is used for the 3D shoulder joint cad model generation in CATIA V5. Muscles are added and then exported to the ANSYS APDL solver for stress analysis. Sensitivity Analysis is done for stress and strain behavior amongst different shoulder muscles; deltoid, supraspinatus, teres minor, infraspinatus, and subscapularies during adduction arm movement. During the individual deltoid muscle analysis, the von Mises stresses induced in deltoid muscle was maximum (4.2175 MPa) and in group muscle analysis it was (2.4127MPa) compared to other individual four rotor cuff muscles. The study confirmed that deltoid muscle is more sensitive muscle for the abduction arm movement during individual and group muscle analysis. The present work provides in depth information to the researchers and orthopedicians for the better understanding about the shoulder mechanism and the most stressed muscle during the abduction arm movement at different ROM. So during rehabilitation, the orthopedicians should focus on strengthening the deltoid muscles at earliest.

• Computers and Concrete
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• v.20 no.4
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• pp.391-407
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• 2017

Fiber reinforced polymer (FRP) bars have been recently used to reinforce concrete members in flexure due to their high tensile strength and especially in corrosive environments to improve the durability of concrete structures. However, FRPs have a low modulus of elasticity and a linear elastic behavior up to rupture, thus reinforced concrete (RC) components with such materials would exhibit a less ductility in comparison with steel reinforcement at the similar members. There were several studies showed the behavior of concrete beams with the hybrid combination of steel and FRP longitudinal reinforcement by adopting the experimental and numerical programs. The current study presents a numerical and analytical investigation based on the data of previous researches. Three-dimensional (3D) finite element (FE) models of beams by using ANSYS are built and investigated. In addition, this study also discusses on the design methods for hybrid FRP-steel beams in terms of ultimate moment capacity, load-deflection response, crack width, and ductility. The effects of the reinforcement ratio, concrete compressive strength, arrangement of reinforcement, and the length of FRP bars on the mechanical performance of hybrid beams are considered as a parametric study by means of FE method. The results obtained from this study are compared and verified with the experimental and numerical data of the literature. This study provides insight into the mechanical performances of hybrid FRP-steel RC beams, builds the reliable FE models which can be used to predict the structural behavior of hybrid RC beams, offers a rational design method together with an useful database to evaluate the ductility for concrete beams with the combination of FRP and steel reinforcement, and motivates the further development in the future research by applying parametric study.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.195-201
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• 2016

An experimental study has been found the air guide grooves for reducing drag. When a bullet is fired and move in the air, the drag is generated. The vortex which is one of the types of drag hinders the movement of the bullet. To solve this phenomenon, cut a negative grooves that we are called the air guiding grooves at the back of bullet. The grooves bullet has identified that the drag compared to conventional ammunition(KM80 and K193) is reduced to 4.480 and 4.054 : 10 % through a Finite Analysis Program($Ansys^{TM}$). Even pressure center was retreating 0.72 % compared to a Bullet(KM80 and K193). Effect obtained with these results is the accuracy of the grooves bullet in a shooting test was improved by over 32 %(KM80: 2.86, air guide grooves : 1.94) compared to conventional ammunition(KM80 and K193). In addition, muzzle velocity is increased 73 m/s. This is expected to be extended the velocity and effective range of bullet. Also, the velocity of the grooves bullet is increased when moving in the air while the velocity of the bullet(KM80 and K193) is reduced. The gas ejected from the muzzle to be balanced and stable flight of the Bullet. Given these effects, we can reckon the air guide grooves have positive influence.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.21-26
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• 2003

Develop and need design application of carbon sex design concept that consider plasticity in elastic design concept until now. To Place that is representative construction of hull in this research rain deflection pattern analysis technique and grandeur increment method such as general load type increment law and displacement type increment law and Newton-Raphson method increment body law to use jointly compare. Specialty. through analysis by initial deflection pattern. examined closely carbon set conduct of place by initial deflection pattern. Applied thin plate structure which receive compressive load used ANSYS that analysis method is mediocrity finite element analysis program to save complicated conduct that effect that conduct after initial buckling and conduct after secondary buckling get in the whole construction is very big and such and grandeur increment law presumes complicated rain fan shape conduct in bifurcation point specially.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.155-163
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• 2006

Car seat is one the most important element to make comfortable drivability. It can absorb the impact or vibration during driving state. In addition to those factors, it is needed to have enough strength for passenger safety. From energy efficiency and environmental point of view lighter passenger car seat frame becomes hot issue in the auto industry. In this paper, weight optimization methodology is investigated for commercial car seat frame using CAE. Optimized designs for seat frame are developed using commercially available finite element code(ANSYS) and design of experiment method. At first, car seat frame is modelled using 3-D computer aided design tool(CATIA) and simplified for finite element modelling. Finite element analysis is carried out for the case of FMVSS 202 Head Restraint test to check the strength of the original seat frame. Two base brackets are selected as optimized elements that are the heaviest parts in the seat frame. After finite element analysis for the brackets with similar load condition to the previous test optimization technique is applied for 10% to 50% weight reduction. Design of experiment is utilized to obtain optimization design for the bracket based on the modified 50% weight reduction model in which outer shape of the bracket is conserved. Weight optimization models result in the decrease of the strength in spite of weight reduction. The more design points should be considered to get better optimized model. The more advanced optimization technique may be utilized for more parts of the seat frame to increase whole seat frame characteristics in the future.