• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.43-49
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• 1998

The deep hole drilling has an increasing demands because of its wide range applications and its good productivity. The BTA drills are capable of machining for having a large length to diameter ratio in single pass to higher degree of accuracy and surface finish. It's really necessary that the investigation for the deep hole drilling by the BTA drill because its required quality should be satisfied with single pass. This thesis deal with the experimental results obtained during single tube BTA system machining on SM55C steel for different machining conditions. The results of the investigation on the optimum cutting condition selecting and tool life reveals as follows. (1) The optimum cutting condition was cutting speed, V = 42 m/min and feed speed. F = 90 mm/min and the tool life was about 10 meters. (2) Surface roughness was $12\mum$ and the roundness was less using $16mum$single edge BTA drill in testing cutting condition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.292-296
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• 2008

Clay-coated rice seeds (clay-coated seeds A and B) were directly sown on dry paddy and their growth and yield were compared with the normal drill-sown seeds on dry flat paddy. In clay-coated seeds, germination was 1 day earlier and the emergence rate was higher up to 5% than that of normal drill-sown seeds. But the apparent number of seedling stand per $m^2$ was lower than that of normal drill-sown seeds, which is due to the smaller amount of seeding in clay-coated seeds. At the early growth stage, the plant height of clay-coated seeds A was taller than that of drill-sown seeds, while the plant height of clay-coated seeds B was 0.7 cm shorter than that of drill-sown seeds. At the late growth stage, however, the difference was insignificant in both cases. The maximum tillering stage was 10 days earlier in drill-sown seeds. Lodging index was the lowest in clay-coated seeds B and there was no difference between clay-coated seeds A and drill-sown seeds. The ratio of stem base weight, culm diameter and culm wall thickness were higher in clay-coated seeds, while the lower internodes (4th, 5th and 6th) length was shorter in claycoated seeds than in drill-sown seeds. In clay-coated seeds, the number of panicle per $m^2$ was smaller, while the number of spikelet per panicle was a little larger than in drill-sown seeds. The rate of ripened grain and brown rice 1,000 grain weight were lower in the clay-coated seeds, thus the yield was $98{\sim}99%$ level of drill-sown seeds. Considering that the amount of seeding in clay-coated seeds was two-thirds of that in drill-sown seeds, it is expected that clay coating method could become an additional technique for direct seeding cultivation.

• Tunnel and Underground Space
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• v.23 no.1
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• pp.42-53
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• 2013

The percussion rate and spacing of the button of drill bit are very important in maximizing the drilling efficiency. Therefore, a series of percussion tests using Hopkinson bar system was carried out to assess the fragmentation performance against the beat rate and spacing of a drill bit. First, single percussion test complemented with numerical simulation was performed to analyze rock fragmentation phenomenon and to describe the fragmentation process. Next, multiple percussion test that repetitively strike the rock sample moving at predetermined rate was carried out to predict drilling efficiency against the button spacing. After the tests, the fragmented volume of the rock was measured by laser scanner and the drilling performance was analyzed using the calculated percussive energy and measured negative volume. Based on the results, the single impact performance of drill bit with 102 mm diameter was predicted.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.225-230
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• 2001

Small diameter drilling which take high precision in cutting work is needed more small hole and high speed working. Especially, small hole deep drilling is one of the most important machining types and its necessity and importance become more and more increasing in the whole field of industry. This paper shows the limit depths with small diameter drills using experimental analysis. The results are gained by tool dynamometer and Labview system and obtained during small diameter twist drilling system on SM45C steel for different machining conditions. The machine and tools are the CNC machining center and twist drill of diameter 1.5mm. And additionally, tool microscope show the relationship between shapes of chips and breakage shapes of small diameter drills.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.2
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• pp.180-186
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• 2008

Purpose: This study was performed to evaluate the effect of the implant recipient site preparation methods on primary stability of implants with the instruments of $Osstell^{TM}$ and $Periotest^{(R)}$ in the iliac bone of cadaver. Methods and materials: The 8 iliac bones in 4 cadavers and implants treated with resorbable blasting media (RBM) were used. $Periotest^{(R)}$ (Simens AG, Germany) and $Osstell^{TM}$ (Model 6 Resonance Frequency Analyser: Integration Diagnostics Ltd., Sweden) were used to measure primary stability of implants. Implants were inserted into the iliac crest of the cadaver. In control group, the recipient site was prepared according to the manufacturer's recommendation: 1.8 mm guide drill, 2.0 mm initial drill, 2.7 mm pilot drill, 2.7 mm twist drill, 3.0 mm twist drill, 3.3 mm pilot drill, 3.3 mm twist drill, and 3.3 mm countersink drill as well as tapping drill were used in order. In the group 1, implant recipient sites were prepared by sequentially drilling from 1.8 mm guide drill to 3.0 mm twist drill and then inserted implants without countersinking and tapping. In the group 2, implant recipient sites were prepared to 3.0 mm twist drill and countersink drill and then inserted implants without tapping. In the group 3, the sites were prepared to 3.0 mm twist drill and countersink drill as well as tapping drill. In the group 4, the sites were prepared to 3.3 mm twist drill. In the group 5, the sites were prepared to 3.3 mm twist drill and countersink drill. A total of 60 implants were placed (n=10). The stability was measured using $Osstell^{TM}$ and $Periotest^{(R)}$ mesiodistally and buccolingually. To compare the mean stability of each group statistically, One-way ANOVA was used and correlation of instrument were analyzed using SPSS 12.0. The results obtained were as follows; 1. The stability of group 1 measured using $Osstell^{TM}$ and $Periotest^{(R)}$ buccolingually showed the highest, and there are significant difference statistically between control group and experimental group 1,2,4 in each instruments respectively (p<0.05). 2. The stability of group 1 measured using $Osstell^{TM}$ and $Periotest^{(R)}$ mesiodistally showed the highest. There are significant difference statistically between control group and all experimental groups in $Osstell^{TM}$, and between control group and experimental group 1,2,3,4 (p<0.05). 3. There are high correlation between the measurements of $Osstell^{TM}$ and $Periotest^{(R)}$ (p<0.05). Conclusion: These results indicate that the primary stability of implant can be obtained by the recipient sites preparation with smaller diameter drill than that of implant or minimal drilling.

• Journal of Periodontal and Implant Science
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• v.50 no.1
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• pp.56-66
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• 2020

Purpose: A stability-measuring device that utilizes damping capacity analysis (DCA) has recently been introduced in the field of dental implantology. This study aimed to evaluate the sensitivity and reliability of this device by measuring the implant stability of ex vivo samples in comparison with a resonance frequency analysis (RFA) device. Methods: Six implant beds were prepared in porcine ribs using 3 different drilling protocols to simulate various implant stability conditions. Thirty-six pork ribs and 216 bone-level implants measuring 10 mm in height were used. The implant beds were prepared using 1 of the following 3 drilling protocols: 10-mm drilling depth with a 3.5-mm-diameter twist drill, 5-mm drilling depth with a 4.0-mm-diameter twist drill, and 10-mm drilling depth with a 4.0-mm-diameter twist drill. The first 108 implants were external-connection implants 4.0 mm in diameter, while the other 108 implants were internal-connection implants 4.3 mm in diameter. The peak insertion torque (PIT) during implant placement, the stability values obtained with DCA and RFA devices after implant placement, and the peak removal torque (PRT) during implant removal were measured. Results: The intraclass correlation coefficients (ICCs) of the implant stability quotient (ISQ) results obtained using the RFA device at the medial, distal, ventral, and dorsal points were 0.997, 0.994, 0.994, and 0.998, respectively. The ICCs of the implant stability test (IST) results obtained using the DCA device at the corresponding locations were 0.972, 0.975, 0.974, and 0.976, respectively. Logarithmic relationships between PIT and IST, PIT and ISQ, PRT and IST, and PRT and ISQ were observed. The mean absolute difference between the ISQ and IST values on a Bland-Altman plot was -6.76 (-25.05 to 11.53, P<0.05). Conclusions: Within the limits of ex vivo studies, measurements made using the RFA and DCA devices were found to be correlated under a variety of stability conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.633-634
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• 2012

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.56-63
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• 1998

The purpose of this is to analyze experimentally how the change of cutting speed have effects on hole over size of cutting hole, surface roughness of workpiece and roundness during the deep hole machining of SM55C with solid BTA drill using BTA drilling system. Conclusion reached is as follows. (1) The diameter was expanded for 25$\mu$m at the first section and then was reduced 0$\mu$m and 15$\mu$m respectively at the 10m and 20m section comparing to the diameter of tool with respect to the variation of cutting length at 70m/min of cutting speed. 0.15mm/rev of feed. (2) It was proved that roughness was below 8.67$\mu$m for the whole section of cutting length. (3) The roundness has been below 12$\mu$m. Regarding the polygon phenomenon, it has been proved that not only uneven best at 70m/min of cutting speed. 0.15mm/rev of feed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.6
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• pp.90-96
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• 1998

The ductile cast iron is austempered at 300, 350 and 40$0^{\circ}C$ temperature in order to investigate the basic factors for monitoring drill wear in automatic production process, and cutting force and AE RMS signals are measured with changing cutting condition for ADI(Austempered Ductile Cast Iron) with different mechanical properties. The signals of cutting force were influenced by cutting speed and feedrate greatly. On the other hand AE RMS signals are influenced by cutting speed where as it is not related with feedrate. As the depth of drilling increases, cutting force shows a slow increase and the value of AE RMS increases until the range of h/d=4. But over the range it increases greatly due to an amount of chip discharge and friction with inner wall of drilling hole, etc. As the drill diameter increases at a constant depth of drilling. Cutting force increases linearly, but the level of AE RMS does not increases linearly due to circumferential velocity and great influence of h/d.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.7-15
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• 2018

Drilling processes require a cutting monitoring function that can be analyzed and gives feedback about strange conditions, tool collision and tool wear in real time. In this study, we proposed a drill monitor using the torque from the main spindle in CNC machine tools and a PROFIBUS network as a PLC-based interface. This paper studied drilling torque changes depending on drill size, the repetition cutting of the drilling and the drill's wear in the same cutting conditions. The material of the drills was high speed steel (HSS) and uncoated. The drills chosen were 2.7 mm, 6.7 mm, and 10.0 mm in diameter. These drills were selected because they had basic holes for their taps.