• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.678-682
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• 1996

Acoustic emission(AE) is monitored during end milling with a sensor attached to the cutting fluid discharge nozzle. Cutting forces are also measured and compared with the AE signals to examine the reliability of the AE signals. It is demonstrated that the AE signals provide reliable informations about the cutting processes and tool states. Moreover, edge chipping and fracture of tools can be successfully detected using both the AE signals and cutting forces.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1515-1522
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• 1990

Ultra precision cutting should be satisfied with two conditions of Mirror Like and shape grade, and especially Mirror Like depends on surface roughness. In this study, in order to develop Mirror Cutting for Al alloy, this was done with edge form of single crystal diamond tool divided into R type and S type. Surface roughness machined by S type tool is more satisfactory than by R type tool, being the lowest value of 13.8nm. In addition, Mirror surface can reach above 90% of reflection rate by both R type and S type tool, but machined surface by R type tool has much more fine fracture portions rather than by S type tool. Even though feed rate decreases from 5.mu.m to 1.mu.m, surface roughness doesn't show improvement.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.8-14
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• 2003

The characteristics of grinding and wear behavior of diamond wheel for grinding ceramic materials was investigated in this study. In case of $Si_3N_4$, the wear of wheel was large, the finding force was relatively stable and the fluctuation of surface roughness n small. On the other hand in case of $Al_2O_3$ and $ZrO_2$, the wear of wheel and surface roughness were decreasing, the grinding force was increasing. During grinding with vitrified bond wheel, $Si_3N_4$ shows renewal of cutting edge while $Al_2O_3$ and $ZrO_2$ show glazing phenomenon of cutting grains. We have found that it possible to observe the behavior of grinding wheel by grinding ratio, grinding resistance, surface roughness and cutting edge ratio. Through the grinding experiments, it was found that grinding life of diamond wheel is 20 times for $Si_3N_4$, and 40 times fir $Al_2O_3$ and $ZrO_2$.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.227-233
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• 2024

Korea achieved its highest ever defense export performance in 2022. Defense exports are the most effective way to promote the defense industry by exporting Korea's weapons to foreign countries. In addition, to continuously supply excellent weapon systems, a solid defense industry must be established. So defense industry exports are an important issue at the national level, the Korea government is actively supporting policies for the Presidential office as a control tower. In particular, the topic of entry into the defense industry export big4 is being raised in Korea. As an innovative defense export promotion plan, this paper presents a strategic plan of joint research and development that export customized to the needs of purchasing countries and securing cutting-edge technology that can possess world-class weapon systems. In other words, in order to secure cutting-edge technology, the military must break away from existing methods and boldly select cutting-edge technology, provide sufficient budget support, and grant autonomy to development agencies. A rapid acquisition system must also be introduced so that this technology can be applied to advanced weapons in a timely manner. Export joint research and development is intended to promote flexible technology transfer excluding ultra-sensitive core technologies and to form strategic partnerships, taking into account the purchasing country's willingness to possess cutting-edge technology. Through this, we have helped Korea's defense industry exports enter the world's big4 through groundbreaking new strategy.

• Convergence Security Journal
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• v.14 no.7
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• pp.37-43
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• 2014

Today, group research efforts are increasing for cutting edge technologies related to climate, radio astronomy, co-utilization of high performance computing resources and more. Accordingly, networks for cutting-edge researches a re also regarded as means for cutting-edge researches nowadays. Therefore, it is necessary for administrating cutti ng-edge network to be considered, reflecting such a current trend. In this sense, 'Research which can help to admin istrate the networks which are usually used as means for a lot researches' was set as a goal of this paper.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.452-455
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• 2004

The influence of wake flow on a flat-plate blade having different shapes near the hailing edge has been investigated in this paper. Two different shapes near the trailing edge namely the pressure surface cutting (TP) and the suction surface cutting (TS) have been used. The calculation has been performed for two different angles of attack (a =10 and 15 degree) in both the cases. RANS equations have been solved using SST-model as a turbulence closure. Cp and CL values obtained for TS are higher compared to those obtained for TP. Also, the vorticity distribution obtained in case of TS is stronger as compared to that obtained in the case of TP The Karmann Vortex is observed in both the cases but it is more clear in TS case. It is found that in the case of TS, flow separation does not occur upto the trailing edge on both the suction and the pressure sides of the blade while in the case of TP, the flow separateson the pressure surface near the trailing edge of the flat-plate blade.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.126-133
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• 2002

The cutting thickness of ultra-precision machining is generally very small, only a few micrometer or even down to the order of a few nanometer. In such case, a basic understanding of the mechanism on the micro-machining process is is necessary to produce a high quality surface. When machining at very small depths of cut, metal flow near a rounded tool edge become important. In this paper a finite element analysis is presented to calculate the stagnation point on the tool edge or critical depth of cut below which no cutting occurs. From the simulation, the effects of the cutting speed on the critical depths of cut were calculated and discussed. Also the transition of the stagnation point according to the increase of the depths of cut was observed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.934-938
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• 2000

This paper presents a laser cutting of 2D image. 2D image in pixel graphic format is converted into vector graphic image by image processing. Bitmap graphics are made easily, but can not being used in application works for geometry transition. The Sobel's Edge detection method is used to find boundary points on 2D image. The points are fitted into curves with sampling and filtering. Sampling can provide efficient computation and filtering reconstuct features in image. The NC code is generated on MURBS curve of the points. Also, the offset of contour and cutting conditions are considered.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.810-813
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• 2000

Burr makes trobles on manufacturing process due to deburring cost, quality of products and productivity. This paper described the results of experimental study on the influence of the cutting parameters on the formation of exit burrs in face milling. The cutting parameters were investigated changing exit angle, rake nagle , lead angle in tool geometry as well as feed per tooth. Also we carried out experimets on several materials. Using the result of experimental study, burr types are classified according to appearance and formation mechanism in exit burr and we are considered the burr formation in each type of burr.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.128-139
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• 1998

In this paper, a finite element method for predicting the temperature and stress distributions in micro-machining is presented. The work material is oxygen-free-high-conductivity copper(OFHC copper) and its flow stress is taken as a function of strain, strain rate and temperature in order to reflect realistic behavior in machining process. From the simulation, a lot of information on the micro-machining process can be obtained; cutting force, cutting temperature, chip shape, distributions of temperature and stress, etc. The calculated cutting force was found to agree with the experiment result with the consideration of friction characteristics on chip-tool contact region. Because of considering the tool edge radius, this cutting model using the finite element method can analyze the micro-machining with the very small depth of cut, almost the same size of tool edge radius, and can observe the 'size effect' characteristic. Also the effects of temperature and friction on micro-machining were investigated.