• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1907-1910
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• 2003

Miniaturized machine tool can be used to produce 3D features based on CNC and PC-NC technology in the micro/meso scale. Wide applications of CNC technology are developed and there are lots of know-hows in the cutting process and their CNC application. It helps micro/meso scale structure to machine components, which can be used directly for practical applications. In the present research, as the machine tool is miniaturized, the manufacturing machine tools costs less when compared to the equipment used in other micromachining technologies. Moreover, with advancement of micro tool technology, the cutting process can be used to produce micro/meso scale parts. In conclusion, the proposed system can reduce the cost by utilizing the current machining technology, and as a result, complex micro/meso parts can be produced efficiently with high productivity.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1793-1797
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• 2003

After the micro turning lathe was developed in the last year by AMR Laboratory in Yeungnam university, a micromilling machine is developed for micro/meso machining. This machine is integrated with PZT-driven micro-sliders, micro-linear encoders, aerostatic spindle which has maximum 150,000 rpm. It is applicable to milling and drilling of micro scale. This paper presents the possibility of micro/meso machining and characteristics of micro end milling process by using micro machine. A machining of micro parts using 0.2 mm flat end mill was achieved by micro-milling machine. Experimental results show the machining capability and positional accuracy of this machine is good enough for machining micro parts.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.396-401
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• 2009

A micro-spherical activated carbon with meso-pore structure of 52~64% and particle diameter of $2{\sim}10{\mu}m$ was prepared for the improvement electrochemical performance of activated carbon as electrode material for electric double layer capacitor. Resorcinol-formaldehyde resin was used as a carbon source in this preparation. According to electrochemical analysis of EDLC using this activated a carbon with showing effects to reduce charge transfer resistance and to increase rate capability, it was found out that micro-spherical activated carbon could be a good method as well as a material for enhancing the performance of electric double layer capacitor.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.377-382
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• 2005

This paper describes the design of micro machine tools system for mechanical machining of micro/meso scale mechanical parts. The micro machining systems such as $\mu-Late$, $\mu-milling/drilling$ machine and $\mu-grinding$ machine are the basic elements constructing $\mu-factory$ which gains more attention recently because of increasing needs of mico and nano-parts in various industrial and medical area. A miniaturized 3-axis milling machine with VCM stage and air spindle and palm-top size micro-late are designed, and air bearing stage and stepwise linear motion system with PZT are studied for motion system. The micro cutting characteristics are investigated experimentally, and reconfigurable machine structures are also considered.

• Interaction and multiscale mechanics
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• v.3 no.1
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• pp.23-37
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• 2010

Concrete is a heterogeneous material consisting of coarse aggregate, mortar matrix and interfacial zones at the meso level. Though studies have been done to interpret the fracture process in concrete using meso level models, not much work has been done for simulating the macroscopic behaviour of reinforced concrete structures using the meso level models. This paper presents a procedure for the mesoscopic analysis of reinforced concrete beams using a modified micro truss model. The micro truss model is derived based on the framework method and uses the lattice meshes for representing the coarse aggregate (CA), mortar matrix, interfacial zones and reinforcement bars. A simple procedure for generating a random aggregate structure is developed using the constitutive model at meso level. The study reveals the potential of the mesoscopic numerical simulation using a modified micro truss model to predict the nonlinear response of reinforced concrete structures. The modified micro truss model correctly predicts the load-deflection behaviour, crack pattern and ultimate load of reinforced concrete beams failing under different failure modes.

• Transactions of Materials Processing
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• v.20 no.1
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• pp.36-41
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• 2011

Meso-scale or micro-scale forming of sheet metal parts has been recently considered as one of the important forming technologies with growing demand on meso/micro products for electric or medical devices. Experimental investigation on the cylindrical meso-cup drawing with hemispherical punch is carried out to examine the limit drawing ratio and thickness distribution of drawn cups. The working parameters chosen in this study are blank diameter, die-corner radius and blankholding force. It is found from the experiments that the limit drawing ratio of 2.4 can be achieved in the case of hemispherical cup drawing and uniform thickness distribution in wider region can be obtained compared with the results of conventional cup drawing.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.249-255
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• 2011

It is complicate problem to optimize removing natural organic matter (NOM) by activated carbon in drinking water treatment because the activated carbon has heterogeneous surface area and pore structure. Seven different coals based activated carbons which have different pore structures were used in the study. Sand filtered effluents which normally used as GAC adsorber influent were used. The molecular weight distribution showed that most of the NOM was bigger than 10,000Da. In this study, systematical approaches such as characteristics of surface area and pore volume were evaluated on NOM adsorption. Especially, the adsorption capacities for NOM were evaluated by effect of micro-pores and meso-pores in surface area and pore structure. The results show that the higher ratio of meso-pore compare to the micro-pore has not only the better adsorption capacities for NOM but also the higher strongly-adsorbable fraction. Therefore, the overall adsorption capacity is increased with higher meso-pore ratio with existing of reasonable micro-pore surface area and volume.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.143-144
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• 2007

• 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 Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.1025-1028
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• 2002

In this paper, a micro-turning lathe is introduced for micro machining of aluminum rod. To give feed motion, stepwise motion[2] actuators are used instead of the conventional inchworm mechanism. These are consisted of two Piezoelectric ceramics; one is for feeding the slider, and the other is for clamping the slider in the guide way of the body. The guide is V-form. The linearity and positional accuracy of the actuators is good enough far high precision motion. Since the system is more compact than the conventional system using three Piezoelectric ceramics, it is applicable for the micro-machine or MEMS unit. To fabricate the lathe, a small spindle unit with ball bearings of diameter of 10 millimeter is built-up on the top the slider. The motion is feed backed with miniaturized linear encoder attached each axis slider. The diamond tool bite is used for cutting tool. The machining is tried to make small diameter rod. The possible diameter that can be machined in this machine is presented as well as chip formation, surface roughness, and machinability.