• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.9
• /
• pp.61-67
• /
• 1997

Hardened layer and compressive residual stress created by carburized treatment effect on bending strength of gear massively. Also, shot peening treatment improves the strength of carburized gear as it does the hardness and residual stress of surface layer. In these days shot peening techniques are welcomed as one of physical improvement ways around the surface of materials. It is used widely because qualitative analysis of shot peening has become possible and surface treatment can be done with very little costs comparaed to other surface improvement methods. Therefore this study investigates the effect of shot peening in surface shape and bending fatigue strength after doing many kinds of shot peening treatments, then doing fatigue test and also explained characteristics of shot peening gear.

• Transactions of Materials Processing
• /
• v.14 no.5 s.77
• /
• pp.439-443
• /
• 2005

Deep drawing and cold forging processes are combined to achieve near net shape forming of automotive part which has not only drum shape but also thickness variation. It is important to find out proper intermediate shape where two totally different forming methods should be joined seamlessly. In the course of development of the combined process, finite element analysis can be utilized effectively to decide optimal position for transferring from the sheet metal work to the bulk forming. Because machining process is eliminated, significant improvement in integrity, reliability, and durability of the part is expected. The developed process combination could be applied in real manufacturing process successfully.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.12
• /
• pp.154-159
• /
• 2004

This study is aimed to diminish the errors which created during transforming from 3D shape created with CAD program to STL file formation. The length strain which created on X-Y axises at STL file transforming is diminished by using the relation between common shape error and shrinkage rate. As the result of study, we have confirmed the length strain in accordance with facetres value. Also, the shape error is compensated with shrinkage rate by error of length strain. so, we could diminish to shape error by several tens micrometer.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.162-165
• /
• 2004

On this study, we improved diaphgram for micro speaker performance using Taguchi method in discrete design space. The design of diaphgram has an effect on performance of micro speaker such as, thickness of diaphgram, shape of diaphgram, etc. Therefore this study carried to decide shape of diaphgram and thickness of diaphgram for minimizing 2nd natural frequency of diaphgram using Taguchi method. we showed improved design factors that minimized 2nd natural frequency of diaphgram. Also, 2nd natural frequency of diaphgram for micro speaker is reduced up to 37 percent maintaining twist mode shape. From the results of ANOVA, 2nd natural frequency of diaphgram for micro speaker have an effect on position of the outer curved shape and thickness of diaphgram.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.891_892
• /
• 2009

This paper presents the rotor study on the deal with the shape design with a flux barrier to minimize the cogging torque of Interior Permanent Magnet Synchronous Motor(IPMSM). In order to consider the notch effect, the torque characteristics according to the shape of notch is performed and analyzed. From the this results, we found that an optimal location and radius of the notch effectively suppresses the torque pulsation of the IPM drive. The rotor shape design also shows improvement in the average torque

• Journal of Magnetics
• /
• v.19 no.4
• /
• pp.411-417
• /
• 2014

This paper presents the shape optimization of a permanent magnet synchronous motor to reduce the torque ripple and iron loss. Specifically, the harmonics of the electromotive force and cogging torque are decreased by adjusting the permanent magnet arrangement and non-uniform air gap length. In addition, an additional flux path along the q-axis is proposed with a unique rotor shape to increase the q-axis inductance and reluctance torque. The improvement in the performance of the proposed model is verified with simulated and experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.10 no.4
• /
• pp.159-167
• /
• 1985

It was demonstrated that the glottal waves are different depending on a kind of vowels in deriving the glottal waves directly from Korean vowels/a, e, I, o, u/ w, ch are recorded by a male speaker. After resynthesizing vowels with five simulated glottal waves, the effects of glottal wave shape on the speech synthesis were compared with in terms of waveform. Some changes could be seen in the waveforms of the synthetic vowels with the variation of the shape, opening time and closing time, therefore it was confirmed that in the speech sysnthesis, the glottal wave shape is an important factor in the improvement of the speech quality.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.102-105
• /
• 2003

The purpose of this study is to examine the influence of the flowability and the compressive strength of concrete after the improving of grain shape of the coarse aggregate and fine aggregate fineness modulus. According to the experimental results, the coarse aggregate after improvement of grain shape it lead to be down by 6% fine aggregate ratio, from 47% to 41%. The 0.5% increase of fine aggregate fineness modulus lead to 3% increase of concrete slump, and 1% reduction of concrete air content. While compressive strength on fine aggregate fineness modulus, it was increased until fineness modulus 3.0, but after it reached by 3.5 it was decreased. The compressive strength of the coarse aggregate after improving the grain shape was decreased by 6% due to loss of the adhesion of cement paste.

• The KSFM Journal of Fluid Machinery
• /
• v.3 no.4 s.9
• /
• pp.15-21
• /
• 2000

An anemometer employing the bulk PTC thermistor as the sensing element is investigated in this study. The numerical and experimental works are carried out to improve the sensitivity problem of the element by focusing fluid dynamics point of view. The typical shape of the sensing element has been used as a rectangular type, but this shape has a sensitivity problem because of flow separations on the sharp edge when the flow direction is different from that of the sensing element. In order to reduce the reading error, the installer has to be very careful about the flow direction. The reading error fluctuation by time as well as the sensitivity problem can be improved considerably through this study. It can be concluded that the small change of the sensor shape can improve the performance of the flow sensor.

• Journal of computational fluids engineering
• /
• v.6 no.3
• /
• pp.10-18
• /
• 2001

Genetic Algorithm(GA) is applied to aerodynamic shape optimization and demonstrated its merits in global searching ability and the independency of differentiability. However, applications of GA are limited due to slow convergence rate, premature termination, and high computing costs. The present aerodynamic designs such as wing shape optimizations using GA have seldom been applied because of high computing costs. This paper has two objects; improvement of the efficiency of GA and application of GA into aerodynamic shape optimization for 2D and 3D wings. The study indicates that GA can be applied to aerodynamic design and its performance is comparable to traditional design methods.