• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.69-76
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• 1994

AE(Acoustic Emission) signal is correlated to workpiece material, cutting conditions and tool geometry during metal cutting. The relationship between AE signal and cutting parameters can be obtained by theoretical model and experiments. The value of CR(Count Rate) is nearly constant in stable cutting, but when the chatter vibration occours, the value of CR is rapidly increased due to the vibration deformation zone. By experimental signal processing of AE, it is more effective than by RMS(Root Mean Square) measurement to detect the threshold of chatter vibration by CR measurement.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.161-169
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• 1993

The elimination of chatter vibration is necessary to improve the precision and the productivity of the cutting operation. A new mathematical model of chatter vibration is presented in order to predict the dynamic cutting force from the static cutting data. The dynamic cutting force is analytically expressed by the static cutting coefficient and the dynamic cutting coefficient which can be determined from the cutting mechanics. The stability analysis is carried out by a two degree of freedom system. The chatter experiments are conducted by exciting the cutting tool with an impact hammer during an orthogonal cutting. A good agreement is shown between the stability limits predicted by theory and the critical width of cut determined by experiments.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.10
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• pp.50-56
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• 1995

Chatter Vibration is an unwanted phenomenon in metal cutting and it always affects surface finish, tool life, machine life and the productivity of machining process. The real-time detection of the chatter vibration is is necessarily required to automation system. In this study, we constructed the multi-sensing system using Tool Dynamometer, Accelermeter and AE sensor. Especially, Acoustic Emission(AE) generated during turning was investigated the possibility for real-time detection of chatter vibration. Turning experiments were performed using carbide insert tip under realistic cutting conditions and tapered workpiece of SM45C. Consquently, the real-time detection using multi-sensing system can be used for Inprocess monitoring of chatter vibration.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.12
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• pp.100-108
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• 1995

The In-process minitoring of the chatter vibration is necessarily required to an automatic manufacturing system. In this study, we constructed a multi-sensing system using tool dynamoneter, accelerometer and AE(Acoustic Emission) sensor for a more credible detection of chatter vibration. And a new approach using a multiple neural network to extract the features of multi-sensor for the recognition chatter vibration is proposed. With the Back-propagation training process, the neural network memorize and classify the features of multi-sensor signals. As a result, it is shown by multiple neural network that the chatter vibration can be monitored accurately, and it can be widely used in practical unmanned system.

• (The) Research of the performance art and culture
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• no.36
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• pp.289-312
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• 2018

Pansori has been passed down over several generations and over time have undergone continued change in accordance with the times, as well as the skills and ability of the singer. Policies regarding intangible cultural treasures were established to preserve and promote the continuing tradition of art forms including Pansori and thus must spare no effort in supporting and preserving the genre. As such, for proper implementation of the newly legislated law, it is necessary to review the agents who pass down the tradition of Pansori and whether there are any areas that need to be changed in terms of our perception of culture in general. Pansory in the $21^{st}$ century features both contemporary aspects and mass appeal and have undergone many changes in how it is enjoyed. It is our responsibility therefore, to establish how the art and universality of Pansori should be promoted. From this perspective, this study reviewed the evolution of law on intangible cultural treasures, the current status of intangible cultural treasures being passed down with a focus on national treasures and those of Jeonbuk Province to shed light on issues. Diversification is needed in the number of those who carry this intangible cultural treasure, as well as the number of categories. To that end, a survey index or practical ability index must be taken into account for the application and designation of intangible cultural treasures. The study also noted issues of the categories for designation as intangible cultural treasures and discussed directions for improvement. In the case of Pansori, suggestions for improvement were presented for the designation of skilled artists by school, regular surveys and regular application, increased role of artists for increased mass appeal, survey of regional singers, supervision and monitoring of skilled artists and establishment of a manual for the education on how to pass down the art form. In doing so, efforts should be made to make the passing down of Pansori more active and related education more systematic. Since we are in the early years of the law on intangible cultural treasures being implemented, areas of improvement will continue to be identified. It is however certain that the proper support for the art form to be handed down should be done in a way where law and culture are complementary given that Pansori is not just a Korean tradition, but a tradition of mankind.

• Journal of Powder Materials
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• v.15 no.5
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• pp.359-364
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• 2008

To satisfy the demand of higher cutting performance, mechanical properties with tungsten carbide (WC-Co) tool materials were investigated. Hardness and transverse rupture strength with WC grain size, Co content and density were measured. Compared to H, K, and S manufacture maker as tungsten carbide (WC-Co) tool materials were used for high-speed machining of end-milling operation. The three tungsten carbide (WC-Co) tool materials were evaluated by cutting of STD 11 cold-worked die steel (HRC25) under high-speed cutting condition. Also, tool life was obtained from measuring flank wear by CCD wear measuring system. Tool dynamometer was used to measure cutting force. The cutting force and tool wear are discussed along with tool material characteristics. Consequently, the end-mill of K, H manufacture maker showed higher wear-resistance due to its higher hardness, while the S maker endmill tool showed better performance for high metal removal.

• Korean Journal of Materials Research
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• v.18 no.12
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• pp.635-639
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• 2008

In this paper, experimental studies of the regrinding of tungsten carbide (WC-Co) tools for high-speed machining were conducted. Regrinding and a subsequent evaluation test were carried out for a flat endmill tool with diameters of 10 mm and 3 mm using a CNC five-axis tool grinder and a CNC three-axis machining center. Tool wear on the two types of endmill tools increased as the cutting length increased, and the tool wear was not influenced by the regrinding state. In case of the micro endmill with a tool diameter of 3 mm, the effective regrinding time was determined for a flank wear threshold of 0.3 mm considering the tool life according to cutting length. The tool lives of the 10 mm and 3 mm endmill tools were increased by 80% and 72%, respectively. This conclusion proves the Feasibility of the recycling of tungsten carbide materials in the high-speed machining of high-hardened materials for industrial applications.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1053-1059
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• 2002

The purpose of this study is to suggest how the machining technique of constant control of cutting speed can improve precision machining and tool life in high speed machining using a ball end mill. Cutting speed is changed in machining fee form surfaces such as connecting rod die. So, we don't have supreme surface form and tool life on machining. To solve this problem we should settle on optimal cutting speeds in free form surface machining. And, to improve precision machining, We must execute high speed machining methods to output optimum NC data using developed constant control of cutting speed program after modeling by CAD/CAM. In this paper, a comparison was made of the cutting precision and tool life in conventional cutting and those in connecting rod machining applying the program developed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.1 no.1
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• pp.38-47
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• 2002

Machining quality has been improved with the development of cutting tools. However, it is difficult to obtain a high degree of quality in machining a deep pocket with a long end mill, since machining accuracy is mainly dependent on the stiffness of the cutting tool and tool holder. To improve machining quality in machining a deep pocket using an end mill, the performance by cutting condition compare with others. Owing to this problem, it is necessary to select suitable tool and holder in the deep pocket machining. In this study, the hydraulic holder for the high speed machining is introduced and the performance of that is compared with others according to cutting conditions. The cutting parameters involved were; slenderness ratio in the range of 3 to 6 (L/D), radial depth of cut from 0.01 to 0.05 mm. Cutting force and surface roughness, precision of form were observed during the experiment to investigate cutting state.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.61-67
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• 2016

The airbag is a widely accepted device for occupant protection in the automotive industry. As the injuries induced by airbag deployment have become a critical issue, revisions to Federal Motor Vehicle Safety Standard (FMVSS) 208 were required to create advanced airbags that can protect occupants of varying statures. In this paper, we developed a new low-risk deployment passenger airbag by adding the Passenger Protection Wrap (PPW). The PPW reduces the cushion impact force to the occupant in order to ensure pressure dispersion. A series of tests were conducted by using FMVSS 208 test procedures to demonstrate the proposed system. It was found that the system not only satisfied the injury criteria of FMVSS 208 but was also effective for protecting passengers of all sizes (male, small female, 3-year-old, 6-year-old).