• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.653-658
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• 2000

For testing machine tools, we used test the work by measure of 3-D object that it was made by the machine tool. By reason of these, we have spent to the cost of measure and have delayed supply to user. In this study, we made a macro-program and a application program in order to test automatic the machine tool. So, if you constitute a ring core and a touch prove in machine tool, you should test the property of machine tool.

• Korean Journal of Metals and Materials
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• v.48 no.7
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• pp.651-659
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• 2010

When high-speed interrupted cutting is carried out for die and mold steels with high hardness, CBN tools manifested a significantly longer wear life than carbide, ceramic, or cermet tools in an experiment of face milling characteristics. In addition, it was also found that they secured a stable surface roughness within a range of 1.6 S~6.3 S, an acceptable range for precision machining for polished machining parts. And it makes them acceptable in the precision machining field, except in industries where very high machining accuracy is required. In the high hardness interrupted cutting, it was advantageous to perform a negaland treatment and a honning treatment on the tools' cutting edge to extend tool life and surface roughness. Also, severe crater development was found on the sloped face in CBN tools following high-speed machining. This caused the cutting edge to be weakened and damaged, and ultimately resulted in a shorter tool life. Finally, as a result of EDX mapping inspection, Cr component was detected evenly on the entire crater wear area, which can be included only in STD 11.

• Journal of The Korean Association of Information Education
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• v.17 no.1
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• pp.23-31
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• 2013

Elementary students can easy access to the smartphones and also can have been interested with them. Elementary learning tools to use smartphones are effective at the learning. So, Smartphones learning tools used in scientific experiments, the learning effect would be nice. Elementary school students to learn speed learning areas is a difficult concept. Therefore, the speed of learning application for smartphones is required. In this study, we develop a module for learning speed. This module that use the acceleration sensors of smart phones extract data from a given point in time, calculated by integrating speed. In addition, the distance is calculated. Students experiment at speed so that you can immediately see the changes in the module proposed in this study has the advantage. Measure the speed of the existing tools students again need to calculate the speed of a hassle to experiment and measured data values are separated. That the module proposed in this study is expected to be able to overcome the disadvantage.

• Journal of KSNVE
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• v.10 no.2
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• pp.299-305
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• 2000

In this study, the characteristics of transmitted vibration on hand-arm system are examined when operating electric hand tools. Also through the correlation analysis between anthroponetric data and transmitted vibration, and comparison study with appropriate amount of work done based on the ISO criteriaa, the basic data for the ergonomic work design can be presented. The types of electric tools and works for the experiment are drill (general type and impact type), grinder, wire brush and steel to analyze the characteristics of transmitted vibrations, the amount of transmitted vibrations in X, Y and Z direction at tool(T), hand(H), wrist(W), and the joint between foream and upper arm(A) were measured at the frequency range of 6.3∼1000[HZ]. Also, the limit of human exposure to vibration, and the response of frequency were conducted.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.278-282
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• 2003

There is a strong industrial demands for the development of light-vehicle to improve fuel efficiency. It is more effective to reduce weight of the parts directly driven by an automobile engine. So the saving in weight of wheels which is operated by an automobile engine improve fuel efficiency more than other parts. There are many step of sheet metal forming in fabricating automotive wheel, so that it is difficult to design process and tools of multi-stage stamping. Traditionally, design process and tools have depended on the experience of skilled workers and it has done by trial and error methods. However, it needs too much costs and time. Taguchi methods has an advantage of the number of required experiments and reliability compared with trial and error method. In this study, Taguchi methods and response surface methods are applied to design process and tools of automotive wheel. As a result, the principal variables are selected and process conditions are optimized.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.73-78
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• 1998

In this paper, we have studied about the thermal expansion of the ball screw used for the CNC machine tools. The hollow ball type is used for the ball screw. We have compared the conventional cooling system and function with the improved cooling system and function which is developed the path providing cooling oil in hollow ball screw. That is the temperature variation and positioning accuracy are analyzed of the ball screw. We have obtained the following results through this experiment. 1) The improved cooling system of the hollow ball screw for CNC machine tools was developed 2) The improved cooling system of the hollow ball screw has a large effectiveness on restraining the thermal expansion of the ball screw. 3) The positioning accuracy of the ball screw was improved about 2~4$\mu$m using temperature -controlled cooling oil.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.151-158
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• 2005

Micro-machine tool is essential in the micro/meso cutting for the sake of saving of space, resources, and energy. In this research, a micro-turning lathe was fabricated with piezoelectric feed drive mechanism, and motion of each axis was generated by stepwise mechanism with two piezo actuators. The resolution to drive the axis was $0.05{\mu}m$ and position accuracy less than $2{\mu}m$ was assured. From the positioning experiment, piezo feed mechanism is good enough for the micro machine tools. Many fuming experiments were carried out with diamond-cutting tools to evaluate cutting capability of a machine tool. Continuous flow type chip could be obtained even if the cutting speed was very low due to small diameter of workpiece. However, thorough investigation about machineability in micro/meso cutting is inevitable to assure high quality surface roughness in micro machine tool.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1724-1727
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• 2002

Asynchronous circuits have the potential to solve the problems related to parameter variations such as gate delays in deep sub-micron technologies. However, current CAD tools for large-scale asyn-chronous circuits partition specification irrelevantly, because these tools cannot control the granularity of circuit decomposition. In this paper we propose a hierarchical Control/Data Flow Graph (CDFG) containing nodes that are flexibly partitioned or merged into other nodes. We show a partitioning algorithm for such CDFGs to generate handleable Signal Transition Graphs (STGs) for asynchronous synthesis tools. The algorithm a1lows designers to assign the maximum number of signals of partitioned nodes considering of timality. From an experiment, this algorithm can flexibly partition and result in more compact asynchronous controllers.

• Journal of the Ergonomics Society of Korea
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• v.18 no.1
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• pp.55-69
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• 1999

It is very common to use the powered hand tools to enhance the productivity in various types of industry. But the use of the powered hand tools could cause health problems such as cumulative trauma disorders and vibration white fingers. In this study. the effects of hand-arm vibration and anatomical hand position on localized muscle fatigue were analyzed. Eight healthy male subjects volunteered for the study. Vibration frequencies of 0, 40, 80, 100, 150, and 200Hz and hand position of flexion and ulnar deviation were selected for the independent variables of the experiment. Median frequency shifting was used as a dependent variable. The results indicated that at the vibration frequency of 40Hz and accelation of 2g, the muscle fatigue was the greatest. For the hand position. there was significant difference between neutral and flexion. and neutral and ulnar deviation, but no difference between flexion and ulnar deviation. These results could be applied in designing powered hand tools to minimize the health problems.

• Proceedings of the Korean Society for Environmental Edudation Conference
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• 2005.12a
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• pp.138-147
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• 2005

In the present study, the middle school students' perception on the environment course was surveyed before and after three different lessons. It was found that most students were taking environment related issues mainly from mass media including internet and broadcasting. The young students were satisfied at practical experiments, but at the same time a few old fashioned experimental programs would not be preferred. Utilization of multimedia such as audio-visual tools was one of the effective tools for the environment class, because it could help to understand even the profound principles of the chemical and physical processes. However, some students did not concentrate on the display, causing frequent disturbance of the class. Since the school for this investigation did not choose the environment as a selective course, practical tools and materials for the experiment should not be sufficient, and thereby a further detailed work must be followed with the students who are taking environment lessons.