• Tribology and Lubricants
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• v.28 no.3
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• pp.136-141
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• 2012

In this paper, we investigated the friction characteristics of $W100^{\circ}{\o}L25m$ ellipse type surface pattern, on bearing steel. These characteristics are researched by utilizing a pin-on-disk wear test machine, under various velocities and other conditions. The reduction of friction is a necessary requirement for the improved efficiency of industrial parts. As the speed increases, there is a decrease in the effect of the dimple of friction characteristic in low velocity, with substantially little change to density. Conversely, as the load increases, the test direction of ellipse type dimple pattern, resulting in a difference in the texture of these two components. At a dimple density of 7.5% the friction characteristic is easily demonstrated, with a consistent change in both speed and load.

• Journal of the Korea Furniture Society
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• v.19 no.6
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• pp.439-446
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• 2008

High Tech Design manner is a design concept that had been constantly discussed in constitution process of the West art history and modem ideology and had been experimented in industry, having started from futurism and structuralism in the early 20th century through Kinetic Art & Technology Art and up to now. High Tech Design had a great influence also on Post Modernism and more important is that this manner of design will be existing continually in the future too. From the modem times when machine civilization started, the artist and designers expressed a utopia will showing the future world with help of High Tech Design and modem people are realizing technology images as a utopia, in the space and material presented by this high tech design. And this utopia imply the images of dynamic power, speed making a voyage in universe, dream of future, hope, mass production, earth's environment, wealth etc. High Tech furniture was lightly designed by using thin steel wire, structure stressing the metallic characteristic and tempered glass, and it was used for presenting a convenient interior space visually, and with that it can make a unified sense in High Tech interior space, and a contrary effect compared with minimal space. High Tech Design equipped with glass and metal materials looking inappropriate for our interior space due to their sharp and cold image has been regularly used as living furniture, not only decoration function, and then there must be reasons for that. This study intends to research how High Tech Design has been changed and developed in the design history & West art history from the early 20th century, and to present it's value of development as data orienting, namely a direction for the industry of the next-generation and furniture design.

• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.16-22
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• 2012

The use of welding process has been increased for manufacture of machine, bridges, ships, gas facilities and so on together with development of welding technique. Accordingly, it has been needed to develop the welding methods considering higher productivity and safety design for manufacture of their welding structures. In this study, it was studied basically on characteristics of fatigue strength and fatigue life in full penetrated cruciform fillet weld zone in relation to material thickness, welding passes, loading direction and notch radius of toe zone. Most of fatigue failure occurred in toe zone of cruciform fillet weld joint. Fatigue strength and fatigue life are under the influence of stress concentration due to notch radius and flank angle of toe zone. The metal of toe zone annealed and diffused by multi-layer welding and acicular ferrite structure formed by the result improved fatigue strength and fatigue life.

• 연구논문집
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• s.23
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• pp.127-140
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• 1993

The drive pulley, which is employed for loading and unloading raw materials in a steel mill, is usually manufactured by use of various welding processes. In this study the weldment in the pulley, in which TIG and $CO_2$ welding processes are used, has been analyzed from view point of fracture mechanics. Fracture toughness tests have been performed according to ASTM E813. A servo-hydraulic testing machine (10kN) has been employed. Also the crack propagation tests (Mode I) have been performed with compact tension specimen in compliance with ASTM E647. To predict the critical crack size in the weldment, finite element stress analysis for the drive pulley under real operating conditions have been performed. In addition, the residual stresses at the weldment and in heat-affected zone have been obtained by hole drilling method. The planar critical crack size have been predicted for the drive pulley by considering the stress analysis results and the residual stresses due to welding process. For the drive pulley considered in this study, it has been concluded that the most important factor in determining the critical crack size is the welding residual stress in the transverse direction. Also the effect of stress concentration at the root of the weldment have been noticeable. For the planar crack, the fatigue crack growth life from an initial crack size of 2mm to the critical crack size obtained as in the above have been predicted. The predicted lives were between 55, 900 and 72, 000 cycles depending on the shape of the elliptical crack. The predicted lives were in fairly good agreement for the drive pulley considered in this study.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.332-335
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• 2018

In recent years, artificial intelligence using big data has become a big issue in IT. Various studies are being conducted on services or technologies to effectively handle big data. The educational field, there is big data about students, but it is only a simple process to collect, lookup and store such data. In the future, it makes extensive use of artificial intelligence, machine learning, and statistical analysis to find meaningful rules, patterns, and relationships in the big data of the educational field, and to produce intelligent and useful data for the actual students. Accordingly, this study aims to design a program to predict the career of students using a decision tree algorithm based on the data from the student's classroom observations. Through a career prediction program, it is believed to be helpful to present application paths to students ' counseling and to also provide classroom behavior and direction based on the desired courses.

• Journal of Korea Port Economic Association
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• v.36 no.3
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• pp.39-54
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• 2020

In the presidential political system, the word of the president has great influence on the formation of national policy and the decision-making process. Policy priorities are determined according to the president's ideology and core values, and various policies are established and executed according to the priorities. Therefore, this paper analyzes the contents of the president's speech. Since the president's speech is a semantic datum, in order to analyze unstructured text, big data analysis is conducted through the methods of machine learning and deep learning. In this study, the president's speech at the "National Sea Day" commemoration was obtained 1996 onwards and analyzed using topic modeling. As a result of the analysis, all the presidents' speeches were delivered with a view of the ocean that was consistent with the direction of their administration. It was confirmed that the ocean-industry-resource topics, which are the intrinsic values of the ocean, were not damaged and consistently emphasized by all presidents.

• Journal of the Korean Data and Information Science Society
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• v.26 no.3
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• pp.611-618
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• 2015

By Wikipedia, big data is a broad term for data sets so large or complex that traditional data processing applications are inadequate. Data mining is the computational process of discovering patterns in huge data sets involving methods at the intersection of association rule, decision tree, clustering, artificial intelligence, machine learning. Association rule is a well researched method for discovering interesting relationships between itemsets in huge databases and has been applied in various fields. There are positive, negative, and inverse association rules according to the direction of association. If you want to set the evaluation criteria of association rule, it may be desirable to consider three types of association rules at the same time. To this end, we proposed a balanced comparative confidence considering sensitivity, specificity, false positive, and false negative, checked the conditions for association threshold by Piatetsky-Shapiro, and compared it with comparative confidence and inversely comparative confidence through a few experiments.

• Journal of Technologic Dentistry
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• v.32 no.4
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• pp.317-325
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• 2010

Purpose: The aim of this study is to make some basic materials to find retention force difference based on the total height of CAD/CAM zirconia abutment used for implant, retention force difference based on how to regulate the height of the abutment, retention force difference based on the size and retention force difference based on the design group. Methods: The retention force was measured by being pulled at the speed of 1mm/min after being combined with zirconia block and abutment using Temp-BOND of Kerr. The experiment was done at the research lab of OSTEM in Busan by useing UNIVERSAL TESTING MACHINE on March 3rd, 2010. Results: After analysing the total height and the retention force, p-value had minor difference by 0.01 statistically. Namely, 3mm, 4mm, 5mm had the retention force difference and we could see retention force difference on 3mm and 5mm at the post test. After analyzing how to regulate the height and retention force, p-value had minor difference by 0.000 statistically. Namely, 1mm and 2mm had the retention difference and we could see that 1mm and 2mm with the total height had retention difference. After analyzing the retention force based on the size, p-value had minor retention force difference by 0.000 statistically. Namely, 7 different size had retention force difference and we could see the size 21.9mm, 32.9mm, 32.9mm, 38.4mm, 48.9mm and 54.9mm had retention force difference. Conclusion: Namely 9 different design group had retention difference and we could see that 9 design group with 5.6.7.8 design group and 9 design group with 1.2.3.4. design group had retention force.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.285-291
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• 2011

The error motion of a machine tool spindle directly affects the surface errors of machined parts. The error motions of the spindle are not desired errors in the three linear direction motions and two rotating motions. Those are usually due to the imperfect of bearings, stiffness of spindle, assembly errors, external force or unbalance of rotors. The error motions of the spindle have been needed to be decreased to desired goal of spindle's performance. The level of error motion is needed to be estimated during the design and assembly process of the spindle. In this paper, the estimation method for the five degree of freedom (5 D.O.F) error motions of the spindle is suggested. To estimate the error motions of the spindle, waviness of shaft and bearings, external force model was used as input data. And, the estimation models are considering geometric relationship and force equilibrium of the five degree of the freedom. To calculate error motions of the spindle, not only imperfection of the shaft, bearings, such as rolling element bearing, hydrostatic bearing, and aerostatic bearing, but also driving elements such as worm, pulley, and direct driving motor systems, were considered.

• Journal of the Korea Computer Graphics Society
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• v.24 no.1
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• pp.19-26
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• 2018

In this paper, we propose a gaze depth estimation method based on a binocular eye tracker for virtual reality and augmented reality applications. The proposed gaze depth estimation method collects a wide range information of each eye from the eye tracker such as the pupil center, gaze direction, inter pupil distance. It then builds gaze estimation models using Multilayer perceptron which infers gaze depth with respect to the eye tracking information. Finally, we evaluated the gaze depth estimation method with 13 participants in two ways: the performance based on their individual models and the performance based on the generalized model. Through the evaluation, we found that the proposed estimation method recognized gaze depth with 90.1% accuracy for 13 individual participants and with 89.7% accuracy for including all participants.