• Architectural research
• /
• v.10 no.2
• /
• pp.37-42
• /
• 2008

This study is to get the proper evaluation of the residual property of reinforced concrete beam exposed to fire. This study focused on the strength resistance and analytical evaluation of RC members exposed high temperature. And this study is the basis analytical research to conduct the other studies. To analysis by the finite element method, the Total-RC program was used to analysis it and the Total-Temp program was also used to analysis the temperature distributions at the section. All of results were compared with the pre-existing experimental data of simple supported beam. Using it, the parameters influencing the structural capacity of the high temperature-damaged RC members and residual strength estimation are investigated. The temperature distribution and the structural capacity at the section are calculated in this step. An application of this method is compared with the heating test result and residual property test for simple supported beam which is subjected to ISO 834 test fire. The results of this study are as follows; 1) The loads-displacement relationship of RC beam, considering initial thermal stress of cross section and heat transfer analysis are estimated comparing analytical value with pre-existing experimental results. 2) by the heating time (0, 1, 2 hours), the results of analysis with parameters show that the load capacity exposing at fire is affected.

• Journal of the Korean Wood Science and Technology
• /
• v.44 no.2
• /
• pp.204-217
• /
• 2016

Modified poplar has emerged as a potential raw material for furniture production. Lack of specific modified poplar strength information; however, restricts applications in the furniture industry especially as related to strength in corner-joints. Optimization of strength in L-shaped corner dowel modified poplar joints under compression loads utilizing finite element analysis (FEA) by Taguchi method with the focus of this study. Four experiment factors (i.e., Structure Style, Tenon Length, Tenon Diameter, and Tenon Gap), each at three levels, were conducted by adopting a $L_9-3^4$ Taguchi orthodoxy array (OA) to determine the optimal combination of factors and levels for the von Mises stress utilizing ANSYS software. Results of Signal-to-Noise ratio (S/N) analysis and the analysis of variance (ANOVA) revealed the optimal L-shaped corner dowel joint in modified poplar is $45^{\circ}$ Bevel Butt in structure style, 24 mm in tenon length, 6 mm in tenon diameter, and 20 mm in tenon gap. Tenon length and tenon gap are determined to be significant design factors for affecting von Mises Stress. Confirmation tests with optimal levels and experimental test indicated the predicted optimal condition is comparable to the actual experimental optimal condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.404-409
• /
• 2004

A compressor loop pipe is the most important part in a refrigerator from the view of structural vibration and noise. Vibration energy generated from a compressor's inner body is transmitted to the shell and outside through the loop pipe. For this reason it is very important to design a compressor loop pipe. But, for geometrical complexity and dynamic nonlinearity of the loop pipe, analysis and design of the loop pipe is very difficult. So the statistical and experimental methods have to be used for design of this system. The response surface method (RSM) becomes a popular meta-modeling technique f3r the complex system as this loop pipe. As starting point of loop pile's optimization, FEA model and simple experimental model are used instead of the real loop pipe model. After RS model was constructed, using sensitivity-based optimizer performed optimization for the loop pipe. And the moving least square method (MLSM) was applied to reduce the approximation error.

• Journal of Welding and Joining
• /
• v.28 no.3
• /
• pp.73-78
• /
• 2010

The purpose of this study is to develop the control technology of the welding distortion caused by Auto NG-GTA(Narrow Gap-GTA) welding process at the STS 304 multi-pass butt weldment. Heat input model for Auto NG-GTA welding process was established and verified by measuring temperature change and molten pool shape at the bead-on-plate weldment. With the heat input model developed, the effect of tension load on the welding distortion at the STS 304 multi-pass butt weldment was evaluated using the thermo-elasto-plastic FE analysis. In accordance with FEA results, the angular distortion and transverse shrinkage sharply decreased with an increase in tension load. This result indicated that tensioning method was an effective countermeasure against the welding distortion of the STS 304 multi-pass butt weldment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2012.10a
• /
• pp.522-527
• /
• 2012

This paper presents a result of the mechanical noise and vibration analysis as well as the electrical characteristics analysis of the permanent magnet (PM) motor according to the driving method that is Brushless DC (BLDC) drive and Brushless AC (BLAC) drive. To do that, the characteristics of the PM motor, which have the same output power but different driving method, are investigated. At that time, the characteristics such as torque, torque ripple and flux density, and so on, are obtained by finite element analysis (FEA). Besides, noise and vibration are obtained by spectrum analysis. The magnetic noise is defined as noise generated from vibrations due to electromagnetic excitation force. In this paper, the electromagnetic excitation force is analyzed and design process of noise reduction is proposed. Finally, The validity of the analysis results is verified by test.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.12
• /
• pp.1820-1827
• /
• 2012

This paper is to present a new method of cogging torque reduction for axial flux PM machines of multiple rotor surface mounted magnets. In order to start softly and to run a power generator even the case of weak wind power, reduction of cogging torque is one of the most important issues for a small wind turbine, Cogging torque is an inherent characteristic of PM machines and is caused by the geometry shape of the machine. Several methods have been already applied for reducing the cogging torque of conventional radial flux PM machines. Even though some of these techniques can be also applied to axial flux machines, manufacturing cost is especially higher due to the unique construction of the axial flux machine stator. Consequently, a simpler and low cost method is proposed to apply on axial flux PM machines. This new method is actually applied to a generator of 1.0kW, 16-poles axial flux surface magnet disc type machine with double-rotor-single-stator for small wind turbine. Design optimization of the adjacent magnet pole-arc which results in minimum cogging torque as well as assessment of the effect on the maximum available torque using 3D Finite Element Analysis (FEA) is investigated in this design. Although the design improvement is intended for small wind turbines, it is also applicable to larger wind turbines.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2515-2518
• /
• 2008

The vacuum interrupter (VI) is widely used in medium-voltage switching circuits due to its abilities and advantages as an environmental friendly circuit breaker. An understanding of the vacuum arc flow phenomena is very important for improving the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and the thermal flow fields, simultaneously. In this study, we have investigated arc plasma constriction phenomena and an effect of AMF on the arc plasma with the high-current vacuum arcs for the cup-type AMF electrode by using a commercial finite element analysis (FEA) package, ANSYS. The simulation results applied with various AMFs and constant Joule heat generation show that strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. However, further studies are required on the two-way coupling method and radiation model for arc plasma in order to accomplish the advanced analysis method.

• Journal of Magnetics
• /
• v.21 no.2
• /
• pp.173-178
• /
• 2016

Six-step commutation control widely used in brushless DC (BLDC) motor can be applied to consequent pole permanent magnet (CPPM) belt starter generator (BSG) with trapezoidal back electromotive force (EMF) in the starter state. However, rotor position detection with three Hall sensors in BLDC motor can hardly be employed in CPPM BSG due to asymmetric flux distribution in each pole side of CPPM BSG. This paper presents a low-cost rotor position detection method for CPPM BSG in which six Hall sensors are proposed to be used based on the analysis of flux distribution by 3D FEA. In the method, the six Hall sensors are divided into three groups and two signals in each group are combined through performing logic operations. In addition, offset angle between back EMF and the related Hall signal can be compensated by moving the Hall sensors. Experiments of a 2 kW CPPM BSG prototype have also been performed to verify the proposed method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.11
• /
• pp.987-994
• /
• 2008

The optimal structure of the Tonpilz transducer was designed. First, the FE model of the transducer was constructed, that included all the details of the transducer which used practical environment. The validity of the FE model was verified through the impedance analysis of the transducer. Second, the resonance frequency, the sound pressure, the bandwidth, and the impulsive shock pressure of the transducer in relation to its structural variables were analyzed. Third, the design method of $2^n$ experiments was employed to reduce the number of analysis cases, and through statistical multiple regression analysis of the results, the functional forms of the transducer performances that could consider the cross-coupled effects of the structural variables were derived. Based on the all results, the optimal geometry of the Tonpilz transducer that had the highest sound pressure level at the desired working environment was determined through the optimization with the SQP-PD method of a target function composed of the transducer performance. Furthermore, for the convenience of a user, the automatic process program making the optimal structure of the acoustic transducer automatically at a given target and a desired working environment was made. The developed method can reflect all the cross-coupled effects of multiple structural variables, and can be extended to the design of general acoustic transducers.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.101-101
• /
• 2009

The purpose of this study is to develop the control technology of the welding distortion caused by Auto NG-GTA welding process at the STS 304 multi-pass butt weldment. For it, heat input model for Auto NG-GTA welding process was established and verified by measuring temperature change and molten pool shape at the bead-on-plate weldment. With heat input model developed, the effect of the tension load on the amount of welding distortion at the STS 304 multi-pass butt weldment was evaluated using the thermo-elasto-plastic FE analysis. In accordance with FEA results, the angular distortion and transverse shrinkage sharply decreased with an increase in tension load. This result indicates that tensioning method was verified as a countermeasure against the welding distortion of STS 304 multi-pass butt weldment.