• 한국기계가공학회지
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• 제12권2호
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• pp.75-80
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• 2013

Cathode is an essential component used in plasma etching process which is to make micro pattern on the silicon wafer. The currently used cathodes produce particles at the high temperature plasma etching process. To overcome this problem, a 'Silicon Only Cathode' was developed. This 'Silicon Only Cathode' requires manufacturing process changes due to the change of shapes, material features, and machining characteristics of work materials. This research investigates the small hole drilling process. The conclusion is that PCD drills with twist angles of $20^{\circ}$ and $25^{\circ}$ were tested for small hole drilling and the experimental results indicate that the drill with $25^{\circ}$ twist angle drill causes less thrust force.

• Journal of Korean Neurosurgical Society
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• 제56권3호
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• pp.243-247
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• 2014

Objective : To analyze the clinical data and surgical results from symptomatic chronic subdural hematoma (CSDH) patients who underwent burr-hole drainage (BHD) at the maximal thickness area and twist-drill craniostomy (TDC) at the precoronal point. Methods : We analyzed data from 65 symptomatic CSDH patients who underwent TDC at the pre-coronal point or BHD at the maximal thickness area. For TDC, we defined the pre-coronal point to be 1 cm anterior to the coronal suture at the level of the superior temporal line. TDC was performed in patients with CSDH that extended beyond the coronal suture, as confirmed by preoperative CT scans. Medical records, radiological findings, and clinical performance were reviewed and analyzed. Results : Of the 65 CSDH patients, 13/17 (76.4%) with BHD and 42/48 (87.5%) with TDC showed improved clinical performance and radiological findings after surgery. Catheter failure was seen in 1/48 (2.4%) cases of TDC. Five patients (29.4%) in the BHD group and four patients (8.33%) in the TDC group underwent reoperations due to remaining hematomas, and they improved with a second operation, BHD or TDC. Conclusion : Both BHD at the maximal thickness area and TDC at the pre-coronal point are safe and effective drainage methods for symptomatic CSDHs with reasonable indications.

• Journal of Korean Neurosurgical Society
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• 제37권4호
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• pp.282-286
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• 2005

Objective: Symptomatic chronic subdural hematoma(CSDH) is a well-known neurosurgical entity and most of the lesion is managed by surgical treatment. The authors analyze the surgical indication and the treatment results of twist drill craniostomy with closed-system drainage(TDD) for the symptomatic CSDH. Methods: From March 2001 through December 2003, 31 patients who were treated with TDD for the symptomatic CSDH and followed more than 6months were included. The radiologic criteria of TDD in this study were 1) homogeneous density of hematoma on computed tomography(CT), 2) no septation of hematoma on magnetic resonance imaging(MRI), and 3) thicker hematoma more than twice thickness of skull. Surgical procedures were performed on the maximum thickness of hematoma on CT/MRI. Short and long Steinman pins were used to penetrate the skull and hematoma membrane. As the 5L catheter was inserted through the drill hole, it was kept for 1 - 7days for the drainage of CSDH. The patients of CSDH were followed with clinical symptoms and CT studies. Results: Most of all the 31 patients were improved. However, one patient was suffered from postoperative epidural hematoma and the other patients have received the secondary operation because of the recurrence of CSDH on 3 months after initial surgery. Conclusion: TDD is safe procedure for the symptomatic CSDH if the patients are selected appropriately.

• 한국기계가공학회지
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• 제13권2호
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• pp.49-54
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• 2014

Skull Melted 3.2YSZ has good physical properties and does not undergo low temperature degradation. Due to these excellent physical and mechanical properties, Skull Melted 3.2YSZ has been studied for use in dental implants. In this study, a ø2.2mm Initial Twist Drill was made using Skull Melted 3.2YSZ; the drilling characteristics were compared with those of the traditional SUS420J drill. The experimental results indicate that the Skull Melted 3.2YSZ drill requires similar thrust forces and has a slightly higher temperature.

• 한국표면공학회지
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• 제28권2호
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• pp.77-82
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• 1995

In this study, we examined the relationships between the coating film's properties, such as microhardness, adhesion of coating fil $m_strate, and machining tool's life time. Samples were prepared by coating TiN on the 5.5 diameter twist drills using reactive ion plating technology, For measuring microhardness and adhesion of fil $m_strate, HSS plate was used for substrate. TiN coated drill's life time was dependent on the adhesion of fil $m_strate and averagely increased by several ten times more than uncoated drill's. The major parameter affecting TiN coated drill's life time was the strong adhesion between coating film and substrate.ate.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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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.

• 반도체디스플레이기술학회지
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• 제14권2호
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• pp.47-52
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• 2015

In this paper, the performance of uncoated- and Titanium nitride aluminium TiAlN-PVD coated- carbide twist drills were investigated when drilling aluminium alloy, Al 6061. This research focuses on the optimization of drilling parameters using the Taguchi technique to obtain minimum surface roughness and thrust force. A number of drilling experiments were conducted using the L9 orthogonal array on a CNC vertical machining center. The experiments were performed on Al 6061 material l blocks using uncoated and coated HSS twist drills under dry cutting conditions. Analysis of variance(ANOVA) was employed to determine the most significant control factors. The main objective is to find the important factors and combination of factors influence the machining process to achieve low surface roughness and low cutting thrust force. From the analysis of the Taguchi method indicates that among the all-significant parameters, feed rate are more significant influence on surface roughness and cutting thrust than spindle speed.

• Journal of Periodontal and Implant Science
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• 제50권1호
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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.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.513-518
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• 1999

In this study, geometrical similarity conditions for drills of various diameters are discussed. The effect of geometrical similarity on the chip shape and forces of different sized conventional drills has been experimentally confirmed. Drilling tests are carried out for SM45C by using the conventional HSS drills. The torque and thrust forces are measured and compared with those chip forms. Chip shape in drilling are affected by three factors being flow angle, side and up curl of the chip. It is found that the feedrate and drill diameter are more affected than cutting speed on the chip form and cutting forces. The similarity conditions gives easily to estimate the chip shape, the thrust and the torque for drills of different diameters.

• 한국생산제조학회지
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• 제5권4호
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• pp.98-107
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• 1996

In order to predict analytically torque, thrust force, tool life and chip formation in drilling, cutting models for chisel edge with various tool-chip contact length were developed in this type. Also, the experimental tests are run with various pilot holes. The following conclusions were obtained from the analysis. \circled1 It's also found experimentally that thrust force(Fz) decreases as pilot hole diameter increases. \circled2 Surface roughness for material(G) is larger that for material(J). The difference over two materials in roughness value about 0.5$mu extrm{m}$. \circled3 Flank wear of the drill in cutting material of G less than any other kinds of materials(F, G, H, I, J). \circled4 In drilling a deep hole on a workpiece over SM45C either twist drill. The chip was conical helix type at the fist suspensely change the two segment type and than two a long pitch helix style.