• Research in Mathematical Education
• /
• v.11 no.3
• /
• pp.177-184
• /
• 2007

The purpose of this paper is to introduce the development of a new Lesson Video-Case Lab (LVCL) program in Suzhou, China. This program involves the creation of several series of hypermedia video-cases on teaching and learning designed to facilitate mathematics teachers' professional development. Each of these video-cases consists of lesson clips, case questions, interviews with experts, comments by peers, responses by students and other related resources. The study has implications pertaining to the use of technology in teacher development, the production of hypermedia video-cases, as well as research on case-based pedagogy and pedagogy in general.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.1
• /
• pp.85-91
• /
• 2013

The machinability of wear-resistible tungsten carbides and the tool wear behavior in machining of V30 and V50 tungsten carbides using PCD (Poly Crystalline Diamond) cutting tool was investigated to understand machining characteristics. This material is one of the difficult-to-cut materials in present, but their usage has been already broadened to every commercial applications such as mining tools, and impact resistant tools etc. Summary of the results are as follows. (1) Tool wear progression of PCD tools in turning of wear-resistible tungsten carbides were observed specially fast in primary cutting distance within 10m. (2) Three components of cutting resistance in this research were different in balance from the ordinary cutting such as that cutting of steel or cast iron. Those were expressed large value by order of thrust force, principal force, feed force. (3) If presume from viewpoint of high efficient cutting within this research, a proper cutting speed was 15m/min and a proper feed rate was 0.1mm/rev. In this case, it was found that the tool life of PCD tool was cutting distance until 230m approximately. (4) In cutting of wear-resistible tungsten carbides such as V30 and V50, it was recognized that the tool wear rate of V30 was very fast as compared with V50. (5) When the depth of cut was 0.1mm, there was no influence of the feed rate on the feed force. And the feed force tended to decrease as the cutting distance was long, because the tool was worn and the tool edge retreated. (6) It was observed that the tungsten carbides were adhered to the flank.

• Journal of Digital Contents Society
• /
• v.16 no.6
• /
• pp.893-900
• /
• 2015

IMO has been proceeding in the maritime SQA for software quality is considered to be essential for the development of the introduction of the e-Navigation In order to ensure software quality, follow the prescribed procedures throughout the software development project and create the output as a result of executing the respective steps. This paper is introduced a case for applying to maritime software development using the tool that is capable of real-time monitoring and automated documentation. Also, It is discussed the improvement of procedures for applying the expected effects and maritime SQA for the tool utilization. The Development of customized tools for maritime SQA that is reflected an improved procedure for tool is the future goals.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.3
• /
• pp.421-430
• /
• 2010

This work describes a derivation process of JIC(Joint Integrating Concept) based JFC(Joint Functional Concept) analysis of an Aegis BMD(Ballistic Missile Defense). JIC is developed through JOC(Joint Operating Concept) and JFC based on capstone strategy and concept. Aegis BMD is a sea-based ballistic missile defense to detect ballistic missile threat, increase engagement battlespace and enable multiple engagement based on Aegis ships. Aegis BMD is a good case of JIC due to performing an Joint operations based on System of Systems under highly complicated NCW environment. This work analyses JFC using QFD(Quality Function Deployment) and UJTL(Universal Joint Task List). From this analysis the JIC of Aegis Korean BMD is derived using a CASE tool.

• Tribology and Lubricants
• /
• v.6 no.1
• /
• pp.82-88
• /
• 1990

In order to investigate tribological effects of coatings on different places on tool wear, commercial quality coated inserts were tested in production speed machining after the coatings on clearance or rake face of coated tools were selectively removed. The experimental results demonstrated that the primary role of coatings in tool wear was the reduction of the thermochemical adhesion between the tool material and workpiece. And the coating on rake face was observed to retard the progress of flank wear. In case of machining carbon steel, multicoated tools showed the most favorable results for considering the notch wear.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.319-320
• /
• 2002

Numerical simulation of chip formation during high speed machining requires knowing the friction at tool/chip interface. This parameter is hardly identified and generally the loadings (temperature, force) during the identification are not similar to those encountered during machining. Thus, Coulomb friction identified with pin-on-disc device is often used to conduct numerical simulation. The used of this technique cannot leads to good numerical results of chip formation compared to the experimental tests especially in the case of low uncut chip thickness. In this contribution, we propose a new method to evaluate the friction at tool/chip interface. In fact several Coulomb friction parameters are identified corresponding to several parts of the cutting tool. Experimental tests have been conducted allowed us to determinate both the level and the distribution of the Coulomb friction. Experimental results are also compared to the results of orthogonal cutting simulation. We show that this technique allows predicting accuracy results of chip formation.

• Korean Journal of Computational Design and Engineering
• /
• v.9 no.4
• /
• pp.334-350
• /
• 2004

Until now, architects have used traditional methods in order to develop architectural forms and use a digital technology as presentation tools. The field of digital technology has been expanded to control easily architectural data, eventually leads to the creation for creative ideas, which were belong to mainly designer's talent. It has been educated by using digital tool in foreign universities but in our case a little university try to do. So we need an adequate curriculum and educational media because of digitalized data, originated architectural form and reduction of time and money. In this paper, as it is surveyed the present situation of architetural education by using digital tool in domestic and foreign country, it can be used as the fundamental data that architectural education by using digital tool is initiated In our universities.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.04a
• /
• pp.410-415
• /
• 2004

Heavy-weight head slides may cause excessive inertia impact ＆ moment on the machine tool structure when they move or stop abruptly during operation. Consequently these inertia impact and unbalanced moment bring transient vibrations and rough sliding motions on the machine structure. Machine tool engineers have tried many kind of feed-slide designs in order to solve this problem; for example, the design optimization of the moving structure for minimum weight and maximum stiffness, box-in-box type slide design, and so on. In this article, force and moment equilibrium equations regarding to the inertia force ＆ moment were derived for each one of a mold M/C's head slides. Furthermore, five different design configurations of head slide assembly were reviewed for its design improvement regarding to force ＆ moment calculations and finite element structural analysis results.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.12
• /
• pp.198-203
• /
• 1999

In this study, chip-tool friction and shear characteristics of cold drawn free machining steels in turning were assessed. To do this, a newly developed equivalent oblique cutting model was adopted. And for comparison with those of free machining steels, chip-tool friction and shear characteristics of conventional carbon steels were also investigated. The Pb-S free machining steel shows superior machinability to others. In case of the Bi-S free machining steel, the shear stress and the specific friction energy are relatively lower than those of conventional carbon steels, but its shear strain is relatively high, so it does not show any remarkable improvement of machinability.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.375-379
• /
• 1997

Thermal drift of the machine tool spindle due to temperature increase dominates the major source of the machine tool error. To compensate the thermal errors, software based error correction methods could be implemented. In th~s case, we need model to map the relationship between temperature and thermal distortion. Traditionally, two or three different methods have been trled: step increase of spindle speed, constant, random. The latter two methods are described in the document of ISOlDIS230-3. In this research, three different methods were verified through the experiments from the viewpoint of compensation of thermal distortion. Constant spindle speed turned out good enough for monitoring the behavior of the thermal drift and modeling the relationship between temperature and thermal distortion.