• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.168-173
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• 2005

Composite material is combined with two or more chemical ingredient and different components. FRP has been widely used for the structure of aircraft, ships, automobiles, sporting goods and other machines because of their high specific strength, high specific stiffness and excellent fatigue strength. Recently, the development of machine tool and cutting tool greatly relies on high speed process to satisfy high precision, high efficient machining, shortened process time to maximize material removal rate (MRR) through high cutting speed and feed speed. The research molded CFRP, GFRP as stacking sequence methods of two direction (orientation angle $0^{\circ}\;and\;0^{\circ}/9^{\circ}$) hand lay-up, drilled molded plates using cemented carbide drill and examined chip shapes, surface roughness properties.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.2
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• pp.36-46
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• 1991

This study was carried out to investigate the characteristic of dynamic component in drilling. Materials used were carbon steel, brass and cast iron, and the drills used were high speed steel drill and cemented carbide. The cutting resistance generated in drilling was detected with the aid of piez0-electric tool dynamometer which has an excellent frequency response, and then the magnitude and shape of dynamic component and its frequency component as well were analyuzed. After a thorough study of interrelationship, the obtained results are as follows; 1) The shape of torque and thrust of the early drilling are different. 2) The shapes of dynamic component can be classified into four kinds. 3) Torque is related to frequency more closely than thrust. 4) As cutting speed increased, dynamic component increased. 5) Chipping took place continuously, and its size decreased as cutting proceeded.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.1-7
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• 2021

In recent years, automated process technology has allowed for the rapid manufacturing of metal parts. Maintaining high product quality is of vital importance during the production of these parts. Surface defects occurring after processing can compromise their assembly precision and performance. In this study, a deburring tool was developed that can remove burrs generated from drilling. Through the evaluation of processing, burrs were completely removed at entrance and exit surfaces. Therefore, this newly developed deburring tool shows better performance than deburring tools currently in use.

• Structural Engineering and Mechanics
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• v.80 no.5
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• pp.503-522
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• 2021

This paper investigates experimentally and numerically the influence of drilling process on the mechanical and thermomechanical behaviors of woven glass fiber reinforced polymer (GFRP) composite plate. Through the experimental analysis, a CNC machine with cemented carbide drill (point angles 𝜙=118° and 6 mm diameter) was used to drill a woven GFRP laminated squared plate with a length of 36.6 mm and different thicknesses. A produced temperature during drilling "heat affected zone (HAZ)" was measured by two different procedures using thermal IR camera and thermocouples. A thrust force and cutting torque were measured by a Kistler 9272 dynamometer. The delamination factors were evaluated by the image processing technique. Finite element model (FEM) has been developed by using LS-Dyna to simulate the drilling processing and validate the thrust force and torque with those obtained by experimental technique. It is found that, the present finite element model has the capability to predict the force and torque efficiently at various drilling conditions. Numerical parametric analysis is presented to illustrate the influences of the speeding up, coefficient of friction, element type, and mass scaling effects on the calculated thrust force, torque and calculation's cost. It is found that, the cutting time can be adjusted by drilling parameters (feed, speed, and specimen thickness) to control the induced temperature and thus, the force, torque and delamination factor in drilling GFRP composites. The delamination of woven GFRP is accompanied with edge chipping, spalling, and uncut fibers.

• Resources Recycling
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• v.26 no.6
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• pp.65-72
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• 2017

APT (Ammonium paratungstate) is widely used in various industries such as metal cutting tools, drill bits, mining tools, and military inorganic materials. In order to produce high purity APT(S), an impurity purification step in an aqueous $Na_2WO_4$ convert $H_2WO_4$ solution is required. It is difficult to remove impurity Na of 200 ppm or less when $H_2WO_4(S)$ is prepared by adding HCl(Aq) to an aqueous solution of $Na_2WO_4$, which is a well-known conventional wet method. However, in this study, a more economical and efficient method of removing Na through electrodialysis using a cationic membrane was studied. A large amount of Na in aqueous solution of $H_2WO_4$ due to $Na_2CO_3(S)$ which was added to dissolve waste tungsten carbide drill and scrap was removed to 20ppm or less through electrodialysis process, and it was confirmed that the effect of Na removal was great when using electrodialysis.

• Advances in materials Research
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• v.11 no.4
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• pp.375-390
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• 2022

Carbon Fiber Reinforced Polymer (CFRP) composite provides outstanding mechanical capabilities and is therefore popular in the automotive and aerospace industries. Drilling is a common final production technique for composite laminates however, drilling high-strength composite laminates is extremely complex and challenging. The delamination of composites during the drilling at the entry and exit of the hole has a severe impact on the results of the holes surface and the material properties. The major goal of this research is to investigate contemporary industry solutions for drilling CFRP composites: enhanced edge geometries of cutting tools. This study examined the occurrence of delamination at the entry and exit of the hole during the drilling. For each of the 80°, 90°, and 118°point angle uncoated Brad point, Dagger, and Twist solid carbide drills, Taguchi design of experiments were undertaken. Cutting parameters included three variable cutting speeds (100-125-150 m/min) and feed rates (0.1-0.2-0.3 mm/rev). Brad point drills induced less delamination than dagger and twist drills, according to the research, and the best cutting parameters were found to be a combination of maximum cutting speed, minimum feed rate, and low drill point angle (V:150 m/min, f: 0.1 mm/rev, θ: 80°). The feed rate was determined to be the most efficient factor in preventing hole entry and exit delamination using analysis of variance (ANOVA). Regression analysis was used to create first-degree mathematical models for each cutting tool's entrance and exit delamination components. The results of optimization, mathematical modelling, and experimental tests are thought to be reasonably coherent based on the information obtained.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.80-88
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• 2003

Object The purpose of this study were to evaluate the microtensile bond strength of resin fiber reinforced post to radicular dentin using resin cement according to various dentin surface treatment and to observe the inter face between post and root dentin under SEM Material and Method A total 16 extracted human single rooted teeth were used. A lingual access was made using a #245 carbide bur in a high-speed handpiece with copious air water spray. The post space was mechanically enlarged using H-file(up to #60) and Gates Glidden bures(#3). This was followed by refining of the canal space using the calbrating drill set provided in ER Dentinpost(GEBR, BRASSELER GmbH&Co. KG). The 16 teeth were randomly distributed into 4 group of 4 teeth. Group 1 teeth had their post space prepared using 10% phosphoric acid as root canal surface treatment agent during 20s. The canal was then rinsed with saline and dried with paper point. Group 2 teeth had their post space prepared using 3% NaOCl as root canal surface treatment agent during 30min. The canal was then rinsed with saline and dried with paper point. Group 3 teeth had their post space prepared using 17% EDTA as root canal surface treatment agent during 1min. The canal was then rinsed with saline and dried with paper point. Group 4 teeth had their post space prepared using 17% EDTA as root canal surface treatment agent during 1min. After rinsing with saline, the canal was rinced 10m1 of 3% NaOCl for 30min. After drying with paper point, the post(ER Dentinpost, GEBR, BRASSELER GmbH&Co. KG) was placed in the treated canals using resin cement. Once the canal was filled with resin cement(Super bond C&B sunmedical co. Ltd.), a lentulo was inserted to the depth of the canal to ensure proper coating of the root canal wall. After 24 hours, acrylic resin blocks($10{\cdot}10{\cdot}50mm$) were made. The resin block was serially sectioned vertically into stick of $1{\cdot}1mm$. Twenty sticks were prepared from each group. After that, tensile bond strengths for each stick was measured with Microtensile Tester. Failure pattern of the specimen at the interface between post and dentin were observed under SEM. Results 1. Tensile bond strengths(meen{\pm}SD$) ) were expressed with ascending order as follows group 4, $12.52{\pm}6.60$ ; group 1, $7.63{\pm}5.83$ ; group 2, $4.13{\pm}2.31$ ; group 3, $3.31{\pm}1.44$. 2. Tensile bond strengths of Group 4 treated with 17% EDTA +3%NaOCl were significant higher than those of group 1, 2 and 3 (p<0.05). 3. Tensile bond strengths of Group 1 treated with 10% phosphoric acid were significant higher than those of group 2 (p<0.05). Tensile bond strengths of Group 4 treated with 17% EDTA +3% NaOCl was significant higher than those of other groups.