• IE interfaces
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• v.9 no.1
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• pp.1-10
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• 1996

In this study, expert system for the selection of the optimal cutting speed and feed rate was developed using NEXPERT system shell. The NC system has been usually used inefficiently because the input command, which contains cutting speed, feed-rate and the depth of cut, is fixed value which depends on principally operator's experience and machining handbooks providing a guideline for applicable ranges. On the other hand, the optimal cutting conditions vary with time, and depend on tool and machine characteristics, work materials, and cost factor and so on. In this study, if cutting factors, such as, cutting method, material type, cutting depth, and tool nose radius are specified, our expert system gets the information about the standard cutting speed form the cutting speed database, and provides optimum feed rate for these cutting conditions. This cutting speed database can be updated by inputting valid cutting speed which is obtained form the practices.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.3
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• pp.29-35
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• 2006

Various types of elliptical motions are generated by PZT mechanism which is composed of two parallel piezoelectric actuators. Elliptical vibration cutting(EVC) is obtained by attaching single crystal diamond cutting tool to the mechanism, and V-grooving for Brass and Aluminum is carried out by applying the EVC. It is experimentally observed that the cutting force in the process of the EVC reduces compared to the ordinary non-vibration cutting, which is due to the decrease of undeformed chip thickness and frictional force between the tool and chip. Ultrasonic elliptical vibration cutting(UEVC) suppresses burr formation and decreases cutting force still more, so UEVC makes it possible to enhance the shape accuracy of machined surface.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.245-250
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• 1999

The experimental study of die-sinking electrical discharge machining for alloy tool steel of STD-11 with circular electrode was conducted for various conditions of the peak current and duty factor with the change of internal size of electrode for distributing the amount of dielectric flow through the electrode. From this study, the material removal rate(MRR) was found to be increased with the peak current and duty factor. The more MRR was obtained for the case of electrode inside diameter of 10mm. The surface roughness and roundness values were analyzed regularity under various conditions, and these values were not affected by the inside diameter change of electrode.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.381-387
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• 2010

This paper presents a study of the influence of fixed pressure in turning. The effect of roundness error and diameter deformation were studied with respect to the fixed pressure applied inside the cylindrical work piece made by boring tool in CNC lathe. The boring tool used in this study is a tungsten carbide coated. The material of workpiece is SM45C and the machining method is dry cutting. Cutting conditions as cutting speed, feed rate and depth of cut are constant. Finally, the change of fixed pressure had influence on the roundness error and diameter deformation.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.362-363
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• 2006

Nano-structured tungsten carbide compacts with cobalt matrices (WC-Co) offer new opportunities for achieving superior hardness and toughness combinations. A unified modeling and simulation tool has been developed to produce maps of sintering pathways from nanocrystalline WC powder to sintered nano-structured WC-Co compacts. This tool includes (1) die compaction, (2) grain growth, (3) densification, (4) sensitivity analysis, and (5) optimization. All material parameters were obtained by curve fitting based on results with two WC-Co powders. Critical processing parameters are determined based on sensitivity analysis and are optimized to minimize grain size with high density.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.11
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• pp.73-81
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• 1996

This paper presents a general procedure for the selection of the machining parameters for a given machine which provides the maximum material removal rate using a Genetic Algorithms(GAs). Some constraints were given in order to achieve desired surface integrity and cutting tool life conditions as wel as to protect machine tool. Such a constrained problem can be transformaed to unconstrained problem by associating a penalty with all constraint violations and the penalties are included in the function evaluation. Genetic Algorithms can be used for finding global optimum cutting conditions with respect to the above cost function transformed by pennalty function method. From the demonstration of the numerical results, it was found that the near optimal conditions could be obtained regardless of complex solution space such as cutting environment.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.30-47
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• 1997

This paper encompasses a general technology in robot deburring automation using solid rotaing burr tools. Deburring is a cumbersome area in finishing technology, where design concept and system implementation is based on knowhows and experiences rather then theoretical development. In the field engineering it is diffcult to find a clue to where and how to start the system design. This paper presents a guide inselection of tool concept of geometry and material. Also, the concept of tool compliance system is introduced, which is one of the most important factor in robot deburring. Typical problems encountered in the field are classified into 20 categories and the solutions are suggested by the proven technology from the expertise. Special problems in polymer and diecasting areas are also briefly mentioned.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.12
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• pp.72-80
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• 1995

Ultraprecision machining technology has been playing a rapidly increasing and important role in manufacturing. However, the physics of the micromachining process at very small depth of cut, which is typically 1 .mu. m or less is not well understool. Shear along the shear plane and friction at the rake face dominate in conventional machining range. But sliding along the flank face of the tool due to the elastic recovery of the workpiece material and the effects of plowing due to the large effective negative rake angle resultant from the tool edge radius may become important in micromachining range. This paper suggests an orthogonal cutting model considering the cutting edge radius and then quantifies the effect of plowing due to the large effective negative rake angle.

• Educational Technology International
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• v.16 no.1
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• pp.58-83
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• 2015

Digital textbooks draw attention as a new format of educational material, using the advantages of information technology; this innovative learning tool requires consideration as a part of successful and effective learning. The main purpose of the article is to investigate the mediating role of self-regulation between digital literacy and learning outcomes (academic performance and learning motivation) when using digital textbooks as a learning tool in Middle School English. Both descriptive and regression analysis were used as data analyses methods. The main findings of this study were as follows: first, digital literacy and self-regulation significantly predicted academic performance and learning motivation; second, self-regulation fully mediated between digital literacy and academic performance; third, self-regulation partially mediated between digital literacy and learning motivation. The research results proved the effects of digital literacy and self-regulation on the learning outcomes and mediating role of self-regulation between digital literacy and learning outcomes. These results help to design and implement effective lessons when using a digital textbook in Middle school English.

• Korean Institute of Interior Design Journal
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• v.23 no.6
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• pp.70-77
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• 2014

The purpose of this study is providing a usage of exterior, interior finish materials and color scheme for architectural design and the actual texture and pattern plans of finish materials from Le Corbuisier's work, Chapel Ronchamp. Chapel Ronchamp was analyzed to support the study for the interaction between texture usage and color expression. As a powerful design tool, texture, pattern and color of finish materials are very effective to alter the perception of the facade in the building. Most of architectural buildings, shapes and materials of elevations are monotonous and uniform. This study should be considered by details in the elevation of Chapel Ronchamp. As the part for developing and planning of architectural design, researching color plans and finish material is very important on real expression in the architectural space. As a result, this study will benefit in planning both the exterior and interior environments of color and finish material with texture and pattern.