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이징구;고성림;고대철
- Journal of the Korean Society for Precision Engineering
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- v.20 no.5
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- pp.57-65
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- 2003
The formation of exit burr in drilling metals is analyzed by finite element method. The simplified burr formation model is suggested for the complex mechanism of burr formation in drilling on the basis of experimental data. Using the model the magnitude of burr is predicted and the effect of material properties of workpiece and cutting condition on burr formation is analyzed in the present study. The suggested model is verified by comparing simulation results and experimental ones. The predicted size and shape of burr are in good agreement with those observed by experiment.
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Oh, Jae-Hyun;Hong, Young-Ho;Park, Jung-Hoon;Kim, Mahn
- Journal of the Korean Ceramic Society
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- v.31 no.11
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- pp.1346-1354
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- 1994
In this study, the formation of magnetite using Fe(II) and Fe(III) hydroxides was investigated; The effects of hydroxide synthesizing pH and temperature, reaction temperature, and total water volume of hydroxide suspensions on the magnetite formation were studied. And the basic reaction behaviors of magnetite formation was discussed in the view of hydroxide formation reaction of Fe(II) and Fe(III) by titration. The characteristics of products were examined by TEM, VSM, XRD. From these experimental data, solid-solid reaction between Fe(II) and Fe(III) hydroxides is proposed as a new ferrite formation mechanism.
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Hong, Suk-Kil;Kang, Gun-Il
- YAKHAK HOEJI
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- v.34 no.3
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- pp.147-154
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- 1990
In order to clarify mechanism of the formation of cinnamaldehyde (CNA) in incubation mixtures of tranylcypromine (TCP) with rat liver microsomes, the CNA formed under various incubation conditions were analyzed. For the purpose, HPLC method of the analysis of CNA was developed. The formation of CNA was found to be dependent on the incubation time and the amounts of microsomes added. In addition, exclusion of NADPH or NADP of NADPH-generating system in incubation mixtures resulted in the formation of markedly decreased amounts of CNA to 8.5 and 2.4%, respectively, relative to the amounts formed each in a standard system. The small amounts measured were comparable to those formed by incubation without microsomes or with boiled microsomes. The results clearly suggested that CNA is a metabolic product of TCP by rat liver microsomes though further studies are needed to suggest details of the steps to the formation of CNA from TCP and of the enzymatic entities involved in the formation of CNA.
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Lim, Eun-Kyung;Yurchyshyn, Vasyl;Goode, Philip;Cho, Kyung-Suk
- The Bulletin of The Korean Astronomical Society
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- v.38 no.1
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- pp.65.2-65.2
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- 2013
A presence of a penumbra is one of the main properties of a mature sunspot, and its formation mechanism has been elusive due to a lack of observations that fully cover the formation process. Utilizing the New Solar Telescope at the Big Bear Solar Observatory, we observed the formation of a partial penumbra for about 7 hours simultaneously at the photospheric (TiO; $7057{\AA}$) and the chromospheric ($H{\alpha}$, $-1{\AA}$) spectral lines with high spatial and temporal resolution. From this uninterrupted, long observational sequence, we found that flux emergence under the stable chromospheric canopy fields resulted in penumbra formation, while emerging flux under the expanding chromospheric fields appeared as transient elongated granules. Based on these findings, we suggest a possible scenario for penumbra formation in which a penumbra forms when the emerging flux is constrained from continuing to emerge, but rather is trapped at the photospheric level by the overlying chromospheric canopy fields.
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