• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.1
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• pp.9-12
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• 2016

Objectives: In this study we evaluated heat generation during the low-speed drilling procedure without irrigation. Materials and Methods: Ten artificial bone blocks that were similar to human D1 bone were used in this study. The baseline temperature was $37.0^{\circ}C$. We drilled into 5 artificial bone blocks 60 times at the speed of 50 rpm without irrigation. As a control group, we drilled into an additional 5 artificial bone blocks 60 times at the speed of 1,500 rpm with irrigation. The temperature changes during diameter 2 mm drilling were measured using thermocouples. Results: The mean maximum temperatures during drilling were $40.9^{\circ}C$ in the test group and $39.7^{\circ}C$ in the control group. Even though a statistically significant difference existed between the two groups, the low-speed drilling did not produce overheating. Conclusion: These findings suggest that low-speed drilling without irrigation may not lead to overheating during drilling.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.4
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• pp.561-571
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• 2019

Drilling and charging of the blast holes during NATM tunneling works take more than 30% of construction time among the whole tunneling work process. Prediction of ground condition ahead of tunnel face has been studied by several researchers by correlating percussion pressure and drilling speed during tunneling work with the ground condition and/or RMR values. However, most of the previous researches were conducted in the granite rock condition which is the most representative igneous rock in the Korean peninsula. In this study, drilling speeds in igneous rocks were analyzed and compared with those in sedimentary rocks (most dominantly composed of conglomerates, sandstones, and shales) under the similar RMR ranges; it was identified that the drilling speed is pretty much affected by rock types even in a similar RMR range. Under the similar RMR values, the drilling speed was faster in sedimentary rocks compared with that in igneous rock. Moreover, while the drilling speed was not much affected by change of the RMR values in igneous rocks, it became faster in sedimentary rocks as the RMR values got lower.

• Journal of Periodontal and Implant Science
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• v.53 no.1
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• pp.85-95
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• 2023

Purpose: In recent years, guided implant surgery has been widely used for the convenience of patients and surgeons. Further streamlining the surgical procedure would make implant surgery more convenient. Low-speed water-free conditions are often used in guided implant surgery. Therefore, in this study, we attempted to confirm once again whether drilling was safe at a low speed without water. The main purpose of this study was to evaluate whether a simplified drilling protocol that omits some intermediate steps in the drilling process was safe from the viewpoint of heat generation. Methods: D1 density artificial bone blocks were drilled under 50 rpm, 10 N·cm water-free conditions, and the surface temperature was measured using a digital infrared camera. First, drilling was performed with the sequential drilling method, which is the most widely used technique. Second, for each drill diameter, the temperature change was measured while performing simplified drilling with omission of the previous 1, 2, or 3 steps. Results: In sequential drilling, the heat generated during drilling at all diameters was less than the critical temperature of osteonecrosis (47℃) except for the ⌀2 drill. Statistical significance was observed in all groups when comparing sequential and simplified drilling in the ⌀3.2, ⌀3.8, and ⌀4.3 drills (P<0.001). However, in the simplified drilling procedures, the temperature was below the osteonecrosis threshold temperature (47℃) except for the ⌀4.3 drill with the omission of the previous 3 steps (⌀3.0, ⌀3.2, and ⌀3.8). Conclusions: In general, drilling under low-speed, water-free conditions has shown stable results in terms of heat generation. Simplified drilling showed statistically significantly greater heat generation than sequential drilling. However, most of the diameters and omitted steps seem to be clinically acceptable, so it will be useful if an appropriate selection is made according to the patient's clinical condition.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.45-51
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• 2010

Electrical discharge drilling (ED-drilling) is a widespread machining method used to bore small holes with a high aspect ratio. This paper presents additional methods by which ED-drilling can improve machining speed, tool wear, and machined surface quality. Firstly, for high machining speed, and low tool wear, a new-type electrode that was ground on one side or both sides of the cylindrical electrodes was suggested to expel debris. The debris which is generated during the machining process can cause sludge deposition and secondary discharge problems: major reasons to decrease machining speed. This new-type electrode also reduced tool wear that was due to the decrease of unstable discharge in a machining gap by helping to expel waste water and debris from the gap. Secondly, to improve the machined surface roughness, an electrolyzation process was included after drilling. This process made the machined surface smooth by means of an electrochemical reaction between an electrode and a workpiece. In this study, the machining speed, electrode wear, and surface roughness were improved by the newtype electrode and the electrolytic process.

• Biomaterials and Biomechanics in Bioengineering
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• v.3 no.1
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• pp.15-26
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• 2016

Based on a survey done recently in Japan, 30 percent of the serious accidents occurred in oral implant surgery were concerned with the mandibular canal and 3/4 of them were related to drilling. One of the reasons lies in the lack of the education system. To overcome this problem, a new educational system focusing on drilling the mandibular trabecular bone has been developed mainly for dental college students in the form of an oral implant surgery training simulator that enables student to sense the reaction force during drilling. On the other hand, the conventional system uses polymeric model. Based on these systems, two approaches were proposed; the evaluation by experienced clinicians using the simulator, and experimental works on the polymeric model. Focusing on the combination of the drilling force sensed and drilling speed obtained through both approaches, the results were compared. It was found that the polymeric models were much softer especially near the mandibular canal. In addition, the study gave us an insight of the understanding in bone quality through tactile sensation of the drilling force and speed. Furthermore, the clinicians positively reviewed the simulator as a valid tool.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.2
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• pp.77-87
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• 1989

This study is carried out to estimate the influence of cutting speed on the dynamic stability of a drilling machine. The theoretical stabilityu chart is constructed by using the measurd dynamic characteristics of the drilling machine. The critical cutting width and speed predicted from the stability chart show excellent agreements with those measured. Therefore it is confirmed that the analysis technique used in this study is useful for the prediction of the dynamic instability and improvement of the dynamic characteristics of drilling machines.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.204-206
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• 2021

Real-time drilling parameters prediction is a considerably important study from the viewpoint of maximizing drilling efficiency. Among the methods of maximizing drilling, the method of improving the drilling speed is common, which is related to the rate of penetration, drillstring rotational speed, weight on bit, and drilling mud flow rate. This study proposes a method of predicting the drilling rate, one of the real-time drilling parameters, using a recurrent neural network-based deep learning model, and compares the existing physical-based drilling rate prediction model with a prediction model using deep learning.

• Journal of Periodontal and Implant Science
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• v.39 no.sup2
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• pp.253-259
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• 2009

Purpose: This study was aimed to evaluate the effect of implant drilling speed on the composition of particle size of collected bone debris. Methods: $Br{\aa}nemark$ $System^{(R)}$ drills were used to collect bone debris from 10 drilling holes (1 unit) at 1,500 rpm (Group A) and 800 rpm (Group B) in bovine mandible. After separating particles by size into > 500 ${\mu}m$, between 250 ${\mu}m$ and 500 ${\mu}m$, and < 250 ${\mu}m$ fractions, particle wet volume, dry volume, and weight were measured and the proportion of 3 fractions of bone debris to total wet volume, dry volume and weight was calculated as wet volume % , dry volume % and weight %. Results: No significant differences were found between Group A and B in wet volume, dry volume, and weight. However, of >500 ${\mu}m$ fractions, Group B had significantly higher wet volume %(P = 0.0059) and dry volume %(P = 0.0272) than in Group A. Conclusions: The drilling speed influenced the composition of particle size in collected drilling bone debris. The drilling in 800 rpm produced the more percentage of large particles than in 1,500 rpm. However, the drilling speed didn't effect on total volume of and weight of bone debris.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1338-1345
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• 2009

Although rock excavation is necessary for the effective utilization of urban space, most conventional rock excavation methods, including the blasting method, cause high noise and vibration. Meanwhile, if a high pressure waterjet system is applied to excavate underground spaces in urban areas, the public grievance can be reduced by low noise and vibration. In this study, an abrasive waterjet system is designed and developed to study the influence of various performance parameters such as jet pressure, nozzle traverse speed, stand-off distance, or abrasive feed rate on waterjet excavation performance in laboratory. Using the developed waterjet system, rock drilling characteristics are identified by measuring drilling depths as a function of the jet exposure time. The drilling depth linearly increases with increasing the jet exposure time(under 60sec). Rock cutting characteristics are also obtained with various jet pressures(1600~3200kg/$cm^2$) and nozzle traverse speeds(1.9~14.1mm/s): The cutting depth is nonlinearly related to the jet pressure and traverse speed. Indeed, the cutting depth increases with an increase in the jet pressure and a decrease in the nozzle traverse speed. This trend can be explained by energy transferring/loss mechanism.

• Journal of the Korean GEO-environmental Society
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• v.17 no.9
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• pp.13-20
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• 2016

This study carried out field measurements of rock drilling where two PRD (Percussion Rotary Drilling) methods, T-4 drilling method and dual drilling method, were considered and the study examined the characteristics of vibration level, noise level, drilling speed, and drillig verticality of the two method. The results of field measurements were compared and analyzed in details to provide the drilling information so that the problems due to rock drilling is minimized and the drilling efficiency is improved in the future. The limited measurements in the field indicated that the dual drilling method showed lower vibration and noise levels and better drilling speed and verticality.