• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.4
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• pp.417-430
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• 2014

A new rock excavation method using an abrasive waterjet system is under development for efficiently creating tunnels and underground spaces in urban areas. In addition, an appropriate abrasive flow rate and abrasive flow quality are important for the new rock excavation (cutting) method using an abrasive waterjet system. This study evaluated the factors influencing the abrasive flow rate and abrasive flow quality, specifically the abrasive pipe height, length, tortuosity and inner diameter, through experimental tests. Based on the experimental test results, this study suggested optimal conditions for the abrasive flow rate and abrasive flow quality. The experimental results can be effectively utilized as baseline data for rock excavation methods using an abrasive waterjet system in various construction locations such as tunnels near urban surroundings, utility tunnels, and shafts.

• Journal of Biosystems Engineering
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• v.35 no.3
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• pp.169-174
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• 2010

This study was conducted to investigate the effect of abrasive processing and non abrasive processing in the milling process on the quality of rice. The effect was analyzed based on the factor such as whiteness, grain temperature, moisture content, crack and broken rice ratio. The results were as followings. Whiteness of abrasive rice was the same as non abrasive rice. The rice temperature increase of abrasive rice was $1.6^{\circ}C$ lower than non abrasive rice. The crack ratio was increased in the process of milling and non abrasive rice showed higher values than abrasive rice. The broken rice ratio of the using abrasive processing was about 0.05% lower than that of non abrasive processing. The moisture content decreased in the process of milling regardless of the use abrasive rice milling machine.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.151-157
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• 2004

In this paper deals with behavior of the magnetic abrasive using sludge on polishing characteristics in a new internal finishing of seamless stainless steel tube applying magnetic abrasive polishing. The magnetic abrasive using sludge-abrasive grain WA and GC used to resin bond fabricated low temperature. And sludge of magnetic abrasive powder fabricated that sludge was crused into 200 mesh. The previous research have made an experiment in the static state the movement of magnetic abrasive grain is nevertheless in the dynamic state. In this paper, We could have investigated into the changes of the movement of magnetic abrasive grain. In reference to this result, we could have made the experiment which is set under the condition of the magnetic flux density, polishing velocity according to the form of magnetic brush.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1877-1880
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• 2003

We were interest in Deburring using MAF(magnetic abrasive finishing) method. So Magnetic inductor was designed and manufactured to generate proper magnetic induction fer deburring the burr formed in drilling SM45C. We experienced according to the Rotational speed, table feed rate, grain size of powder and working gap are changed to investigate the effect on deburring. At this time we experienced in abrasive effect mainly.

• Journal of the Speleological Society of Korea
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• no.81
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• pp.1-5
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• 2007

The magnetic polishing is the useful method to finish some machinery fabrications by using magnetic power This method is one of the precision techniques and has an aim for clean technology in the transportation of the pure gas in the clean pipes. The magnetic abrasive polishing method is not so common in the field of machine that it is not known to widely. There are rarely researcher in this feilld because of non-effectiveness of magnetic abrasive. Therefore, in this paper we deals with the development of the magnetic abrasive with the fse of Sr-Ferrite. In this development, abrasive grain A has been made by using the resin bond fabricated at low temperature. And magnetic abrasive powder was fabricated from the Sr-Ferrite which was crushed into 200 mesh. The XRD analysis result shows that only A abrasive and Sr-Ferrite crystal peaks were detected, explaining that resin bond was not any more to contribute chemical reaction. From SEM analysis, we found that A abrasive and Sr-Ferrite were strongly bonding with each other.

• Design & Manufacturing
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• v.2 no.4
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• pp.44-47
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• 2008

The magnetic polishing is the useful method to finish some machinery fabrications by using magnetic power. This method is one of the precision techniques and has an aim for clean technology in the transportation of the pure gas in the clean pipes. The magnetic abrasive polishing method is not so common in the field of machine that it is not known to widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in this paper we deals with the development of the magnetic abrasive with the use of Sr-Ferrite. In this development, abrasive grain A has been made by using the resin bond fabricated at low temperature. And magnetic abrasive powder was fabricated from the Sr-Ferrite which was crushed into 200 mesh. The XRD analysis result shows that only A abrasive and Sr-Ferrite crystal peaks were detected, explaining that resin bond was not any more to contribute chemical reaction. From SEM analysis, we found that A abrasive and Sr-Ferrite were strongly bonding with each other.

• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.46-49
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• 2003

The magnetic polishing is the useful method to finish some machinery fabrications by using magnetic power. This method is one of the precision techniques and has m aim for clean technology in the transportation of the pure gas in the clean pipes. The magnetic abrasive polishing method is not so common in the field of machine that it is not known to widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in this paper we deals with the development of the magnetic abrasive with the use of Ba-Ferrite. In this development, abrasive grain WA has been made by using the min bond fabricated at low temperature. And magnetic abrasive powder was fabricated from the Ba-Ferrite which was crushed into 200 mesh. The XRD analysis result shows that only WA abrasive and Ba-Ferrite crystal peaks were detected, explaining that resin bond was not any more to contribute chemical reaction. From SEM analysis, we found that WA abrasive and Ba-Ferrite were strongly bonding with each other.

• Journal of Biosystems Engineering
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• v.7 no.2
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• pp.72-85
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• 1983

Rice whitening is performed by basically two different whitening actions known as abrasive and frictional. The former adopted in the emery stone abrasive type whiteners and the latter in the jet-air friction type. Comparative milling yields and whitening efficiencies between the whitening system consisting of jet-air friction type whiteners only and the system consisting of both abrasive- and jet-air friction-types have not yet been rigorously defined. This study was to examine the effect of combined operations of abrasive- and jet-air friction-type rice whiteners on milling yields and whitening efficiencies. The small capacity commercial units of the abrasive- and friction-type whiteners were used for the experiments. The combinations of whitening treatments were: 1) Once in the abrasive type and then two to three times in the friction type, 2) twice in the abrasive and then two to three times in the friction type and 3) three to five times in friction type. In these tests, counter pressures for the friction type whiteners were established differently as required to get about the same degree of whitening at the end of predetermined numbers of the repeated operations. The speed of emery stone and the slot angle of the screen were also the factors varied in the abrasive type whitener. Sheukwang rice variety having 13.05% M.C. was used in the tests. The dependent variables were the milled- and head-rice recoveries and electricity consumption. The results of the study are summarized as follows: 1. It was found that in the whitening systems consisting of abrasive- and friction-type whiteners slot angle of the screen, the rotational speed of emery stone roller had significant effect on the milling yields and whitening efficiency. In general, the increase of the emery stone roller speed from 690 to 950 rpm presented a positive effect on milling yield, and one-pass abrasive milling combinations had higher milling yields than two-pass abrasive milling combinations. 2. It was apparent that if the slot angle of the screen and the speed of emery stone roller are modified and set at an optimum level, the combination whitening system consisting of abrasive- and friction-type whiteners is better than the pure frictional whitening system consisting of jet-air friction type in terms of milling yields and efficiencies. 3. In the rice whitening system consisting of abrasive- and jet-air friction-type whiteners, the best whitening performance was obtained when the slot angle of the screen and the rotational speed of emery stone roller were $45^{\circ}$ and 950rpm, respectively, for the one-pass abrasive milling combinations. However, for the two-pass abrasive mi11ing combinations, the best performance was obtained with $75^{\circ}$ of slot angle and 950 rpm of the emery stone roller speed. 4. As compared with pure frictional whitening systems, the combination systems produced more milled rice by 0.8-1.0% point and more head rice by 0.5-1.5% point, and consumed less electricity by 0.15-0.20 KwH per 100kg of milled rice when the abrasive whiteners were operated in the modified conditions as described in item 3 above. Further study is recommended to find out optimum operational and design conditions of abrasive type whiterners.

• Journal of the Speleological Society of Korea
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• no.79
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• pp.77-81
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• 2007

In this paper deals with behavior of the magnetic abrasive using Sr-Ferrite on polishing charateristiccs in a internal finishing of staninless steel pipe a tying magnetic abrasive polishing. The magnetic polishing is the useful method to finish some machinery fabrications by using magnetic power. This method is one of the precision techniques and has in aim for clean technology in the transportation of the pure gas in the clean pipes. The magnetic abrasive polishing method is not so common in the field of machine that it is not known to widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in this paper we deals with the development of the magnetic abrasive with the use of Sr-Ferrite. In this development, abrasive grain SiC has been made by using the resin bond fabricated at low temperature. And magnetic abrasive powder was fabricated from the Sr-Ferrite which was crushed into 200 mesh. The XRD analysis result shows that only SiC abrasive and Sr-Ferrite crystal peaks were detected, explaining that resin bond was not any more to contribute chemical reaction. From MACRO analysis, we found that SiC abrasive and Sr-Ferrite were strongly bonding with each other.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1832-1835
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• 2003

This paper suggests the selective ultra precision polishing techniques for micro die and mold parts using magnetic-assisted machining. Fabrication of magnetic abrasive particle and their polishing performance are key technology at ultra precision polishing process of micro parts. Conventional magnetic abrasives have disadvantages. which are missing of abrasive particle and inequality between magnetic particle and abrasive particle. So, bonded magnetic abrasive particles are fabricated by several method. For example, plasma melting and direct bonding. Ferrite and carbonyl iron powder are used as magnetic particle where silicon carbide and Al$_2$O$_3$ are abrasive particle. Developed particles are analyzed using measurement device such as SEM. Possibility of magnetic abrasive and polishing performance of this magnetic abrasive particles also have been investigated. After polishing, surface roughness of workpiece is reduced from 2.927 $\mu\textrm{m}$ Rmax to 0.453 $\mu\textrm{m}$ Rmax.