• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.72-77
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• 2018

In this study, cutting robot system which could cut lateral protrusion into main pipes at the connection of sewer pipes was developed. In addition, the cutting test of the robot for the lateral protrusions were performed. The test parameters included materials used in the main pipes and diameters of the pipes, and materials used in the protruded pipes. The materials type of the main pipes were concrete and PE, and the diameters of the pipes were 300 and 500 mm. The materials type used in the protruded pipes were PE and PVC, and the diameter of the pipes was 100 mm. Remaining length of each lateral protruded pipe was less than 5 mm which was an target value of cutting performance. It showd that test results were within the target value. Therefore, in the repair of sewer pipes, the lateral protruded pipes can be cut by using the robot system developed in this paper.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.111-118
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• 2023

For the implementation of a smart factory, it is necessary to collect data by connecting various sensors and devices in the manufacturing environment and to diagnose or predict failures in production facilities through data analysis. In this paper, to predict the residual useful lifetime of milling insert used for machining products in CNC machine, weight k-NN algorithm, Decision Tree, SVR, XGBoost, Random forest, 1D-CNN, and frequency spectrum based on vibration signal are investigated. As the results of the paper, the frequency spectrum does not provide a reliable criterion for an accurate prediction of the residual useful lifetime of an insert. And the weighted k-nearest neighbor algorithm performed best with an MAE of 0.0013, MSE of 0.004, and RMSE of 0.0192. This is an error of 0.001 seconds of the remaining useful lifetime of the insert predicted by the weighted-nearest neighbor algorithm, and it is considered to be a level that can be applied to actual industrial sites.

• Journal of Life Science
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• v.13 no.6
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• pp.917-923
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• 2003

The present investigation was conducted to determine the chemical oxygen demand (COD) removal efficiency by Pseudomonas aeruginosa EMS1. The COD removal efficiency in the medium containing 1% metal working fluid (MWF) was 12% after cultivation of 4 days. The composition of optimum medium for the COD removal efficiency of 1% MWF by P. aeruginosa EMS1 were NH$_4$Cl 0.3%,$ K_2HPO_4\; 0.05%,\; KH_2PO_4\; 0.04%,\; MgSO_4.7H_2O\; 0.05%,\; CaCl_2.2H_2O 0.03%$ and $FeSO_4.7H_2O$ 0.04% at initial pH 7.0 and $30^{\circ}C$. Under this condition, the highest the COD removal efficiency was observed after 4 days.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1148-1153
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• 2003

An adequate method for the prediction of machining errors is essential to improve productivity and product quality. But it is known that there is a remarkable difference between values calculated by conventional roughness model and measured values of actual machined surfaces under high efficient cutting condition. This paper introduces the theoretical analysis of characteristic lines of cut remainder to evaluate a geometrical surface roughness accurately. In this study, analytic equations of the characteristic lines are derived from the surface generation mechanism of ball end milling considering the actual trochoidal trajectories of cutting edges. The predicted results are compared with the results of conventional roughness model.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.51-60
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• 2004

Ball-end milling is one of the most common manufacturing processes for the parts with sculptured surface. However, the conventional roughness model is not suitable for the evaluation of surface texture and roughness under highly efficient machining conditions. Therefore, a different approach is needed for the accurate evaluation of machined surface. In this study, a new method, named ‘Ridge method’, is proposed for the effective prediction of the geometrical roughness and the surface topology in ball-end milling. Theoretical analysis of a machined surface texture was performed considering the actual trochoidal trajectories of cutting edge. The characteristic lines of cut remainder are defined as three-types of ‘Ridges’ and their mathematical equations are derived from the surface generation mechanism of ball-end milling process. The predicted results are compared with the results of conventional method. The agreement between the results predicted by the proposed method and the values calculated by the simulation method shows that the analytic equations presented in this paper are useful for evaluating a geometrical surface roughness of ball -end milling process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.910-913
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• 2001

Rapid Prototyping(RP) techniques have unique characteristics according to their working principle: the stair-stepped surface of a part due to layer-by-layer stacking, low building speed, and additional post-processing to improve surface roughness. A new RP process, Variable Lamination Manufacturing by using expandable polystyrene foam(VLM-S), has been developed to overcome the unfavorable characteristics. The objective of this study is to investigate the thermal characteristics and skeleton size effects as the hotwire cuts EPS foam sheet in order to improve dimensional accuracy of the parts, which is produced by VLM-S. Empirical and analytical approaches are performed to find the relationship between cutting speed and heat input, and the relationship between maximum available cutting speed and heat input. In addition, empirical approaches are carried out to find the relationship between cutting error and skeleton size, and cutting deviation and skeleton size. Based on these results, the optimal hotwire cutting condition and available minimum skeleton size are derived. The outcomes of this study are reflecting in the enhancement of VLM-S input data generation S/W.

• The korean journal of orthodontics
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• v.27 no.5 s.64
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• pp.791-800
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• 1997

Sixty premolars extracted for orthodontic treatment were divided into four groups, and the residual resin was removed with four different rotary finishing instruments at a fixed speed of $18,500{\pm}300 rpm$ on the low speed handpiece. The instruments were G1; No.169L carbide fissure bur, G2: No.2 round bur, G3; No.4 round bur, G4: No.8 round bur. Then, the enamel received a S-second polishing with a rubber cup and a pumice. To find the extent of loss on the enamel at this point, prophylaxis was done with the rubber cup and pumice prior to bonding of the bracket(P1) and removal of residual resin by means of appropriate procedure applicable to each respective group(P2) followed. The final polishing was done with the rubber cup and pumice(P3), and the enamel surface roughness was measured each by the surface measuring instrument. The whole process was observed under a scanning electron microscope to gain the following results: At P2, the enamel surface roughness in G1 showed most smoothly with $2.60{\pm}0.55{\mu}m;\;in\;G2,\;3.24{\pm}0.80{\mu}m;\;in\;G3,\;3.44{\pm}0.94{\mu}m;\;in\;G4,\;3.89{\pm}0.54{\mu}m$, the roughest. G2 and G3 showed no statistical significance(P>0.05). At P3, the enamel surface roughness in G1 showed most smoothly with $2.29{\pm}0.47{\mu}m;\;in\;G2,\;2.44{\pm}0.56{\mu}m;\;in\;G3,\;2.44{\pm}0.56{\mu}m;\;in\;G4,\;2.92{\pm}0.43{\mu}m$, the roughest. G1 vs G2, G3, and G2 vs G3 had no statistical significances(p>0.05). In all groups, P2 and P3 showed rougher in surface roughness than P1, and P2 rougher than P3(p<0.01). In a case of 5-second prophylaxis with the rubber cup and the pumice on a virgin, normal enamel, fine scratches were found under the scanning electron microscope. In all four groups, unremovable gouges remained even after polishing with the ubber and pumice; residual resin was not observed with naked eye when finished with the rubber and pumice, but the resin debris was observed under the scanning electron microscope.