• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.56-62
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• 2014

During the hot forging process, the most common cause of tool failure is wear. Tool wear results in the gradual loss of part tolerances, after which eventually the tool must be replaced or repaired. In order to maximize the lifetimes of forging tools, it is important to investigate the wear mechanisms of these tools. In this study, the hot forging of the outer race of an automotive constant-velocity joint was analyzed by a finite element method to investigate the wear distribution, especially the amount and location of the maximum expected wear damage, using Archard's wear model, which was modified considering the forging temperature. Forging analyses were carried out after modifying blocker forging tools based on established versions. The modified blocker tools resulted in an increase in the tool life up to 31% with a finisher punch.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.358.2-358
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• 2002

To improve the driving sensitivity of an optical pickup actuator for high density and high speed drive, we present a new actuator design using multipolar flux-density distribution by magnetic materials and Nd-Fe-B sintered magnets. We expect this actuator to use in 3-axis actuator fur tilt compensation as well as conventional 2-axis actuator. The electromagnetic field analysis applying 3-D FEM was performed and several samples were actually tested. From comparing simulated data with experimental results, we verified theaccuracy of the simulation and the superiority of the presented method.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.249-251
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• 2001

A novel technology for recycling valuable metals contained in waste dry-battery by vacuum metallurgy was devised by theoretical analysis. On the condition of the total chamber pressure of 1.013$\upsilon$10$^1$Pa, Hg, Cd and Zn are distilled in the temperature range of 773~973K, Pb is volatilized in the range of 1173~1273K while Mn, Cu, Fe and C are remained in residual. MnO$_2$and ZnO are reduced by carbon in waste dry-battery in 773~1273K. Pure metals including Zn, Cd, Hg and Pb can be recovered respectively from their mixed vapor by fractional condensation. Metal Cu and MnO$_2$can be obtained from the residual by hydrometallguical method. The technology can eliminate the pollution of Cd, Hg and Pb to environment.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.19-21
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• 1997

This paper treated a new method that generates the dipole magnetic field for high speed machines by using Halbach array, which was suggested by Klaus Halbach. The Halbach array can produce the various field distribution without magnetic materials. Therefore, the iron losses can be reduced. This paper presented the magnetic characteristics on both linear and cylindrical Halbach array. And the Halbach array for dipole field was manufactured with Nd-Fe-B magnets having 1.17(T), the measured flux density was compared the theoretical values acquired by three dimensional FEM analysis. Finally, the magnetic characteristics of Halbach array were compared with those of other conventional dipole field systems.

• Fashion & Textile Research Journal
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• v.4 no.4
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• pp.394-398
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• 2002

The purse of this study was to invesigate the dyeing fastness on extract of bufferbur leaf princeps. The experimental items were divided into the mordant treatment, component of fabric and kind of mordants. The experimental study was done by laundering, abrasion (dry/wet), perspiration (acid/alkali), light, iron fastness test and color difference by C.C.M system. The summerized finding resulted from experiments and investigation are suggested as follows : In the C.C.M test on mordanting method and kind of fabric, color difference of silk was three times higher than cotton. The silk fabric was the highest in simultaneous mordant treatment but cotton fabric was the highest in none mordant. In color difference analysis on 6 mordants, that of silk and cotton was significantly improved when mordants was treatmented. Especially color difference of Fe and Cu mordanting treatment was higher than Cr, Sn, Al and none. In dyeing fastness on mordants laundering, perspiration, abrasion and iron fastness showed 4-5 grade but light-fastness showed 1-3 grade.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.121-125
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• 2001

We study the feasibility of synthesizing Si particles using PLA method. In the previous studies, it was possible to control the size of Si nanoparticles by the He gas pressure. In this study, we fabricated sub-micron size Si particles with various shapes such as conical, hexagonal, and ring by controlling not only the ambient gas pressure but also the laser energy density. Furthermore, we found that the conical Si particles were uniform-sized and had step shape when observed from FE-SEM and AFM. The conical Si particle has the same crystal structure as the bulk single crystalline Si by the analysis of the Raman scattering. It is shown that the relationship between the laser energy density and the He gas pressure inside the chamber affects the shape of the Si particle.

• Journal of Sensor Science and Technology
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• v.16 no.5
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• pp.355-360
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• 2007

Highly sensitive thick film ethanol gas sensors based on a nanocrystalline $In_{2}O_{3}$ were fabricated by painting method on alumina substrates. The crystal structure of the $In_{2}O_{3}$ powder was characterised by XRD analysis. The microstructure of the films were characterised using FE-SEM. The experimental results of the ethanol gas sensing characteristics indicated that the undoped $In_{2}O_{3}$ thick film has a high sensitivity. The sensitivity of the film heat treated at $400^{\circ}C$ for 2 hrs. was as high as 32.73 at an operating temperature of $200^{\circ}C$ to 1000 ppm ethanol gas in air.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.210-217
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• 2005

This study examined the effect of cancellous bone microstructure on stress distribution within a premolar tooth and a dental implant against mastication force by the micro-finite element method (FEM). The mandibular specimen including a premolar was obtained from a cadaver and scanned with micro-CT to obtain CT images. FE models were reconstructed from CT images at mid-sagittal plane of the tooth. Six models were generated and analyzed for different structure and density in cancellous bone. Stress distributions fur each implant (or tooth) and the surrounding bone were compared. The study indicated that the microstructure of cancellous bone should be considered in finite element analysis to produce reasonable results and thus implant systems with high success rate.

• Transactions of Materials Processing
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• v.20 no.6
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• pp.427-431
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• 2011

In general, hot stamped component is trimmed by costly and time consuming laser cutting when the material strength is over 1,500MPa. The aim of this work was to demonstrate that the trimming die life is improved and the trimming load is decreased by lowering the strength of the region to be trimmed. The model employed in this study was a hat shape, similar to the cross section of many hot stamped products. FE-analysis of hot stamping process was performed to evaluate the effect of tool shape on cooling rate at the area to be trimmed. The best tool shape was thus identified, which created slower cooling and lower hardness at the region to be trimmed. The wear at the cutting tool edge was also reduced.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.130-135
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• 2013

Until now, passenger airbag design is based on the referred car design and many repetitive crash tests have been done to meet the crash performance. In this paper, it was suggested a new design process of passenger airbag. First, key performance factors were determined by analyzing the injury risk effectiveness of each performance factor. And it was made a relationship between injury risk and performance factor by using the response surface model. By using this one, it can be predicted the injury risk of head and neck. Predicted injury risk of optimal design was obtained through this injury risk prediction model and it was verified by FE analysis result within 18% error of head and 9% error of neck. It was shown that a target crash performance can be met by controlling the key performance factors only.