• 대한기계학회논문집A
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• 제32권8호
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• pp.633-641
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• 2008

Recently, the necessity for diagnosis and management of pipes has emerged as the issue due to contamination of water supply generated by corrosion of pipes. Although inspection has been performed with industrial endoscopes, the method has limits for full diagnosis of pipes due to the lack of working range. As a solution for this problem, many locomotive mechanisms for a micro robot with endoscope functions were proposed. In this paper, we analyze the locomotive mechanism of crawling robot proposed as locomotive device for pipe inspection. Based on a mechanical modeling of motor and micro robot inside small pipe, the theoretical formula for velocity is obtained. This derived theoretical formula is demonstrated the feasibility through the comparison with experimental result. Also, we could find the most important element influencing the moving velocity of micro robot when the robot operates in small pipe. Consequently, it is expected that this study can supply useful information to design of crawling robot to move in small pipe.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.118-121
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• 2004

Manufacturing process for milli components has recently gained researcher's focus with the increasing tendency toward highly integrated and micro-scaled parts for electronic devices. The milli-components cannot be formed by the conventional manufacturing process since the parts require higher dimensional accuracy than the conventional ones. In order to enhance the forming accuracy and productivity, various forming procedures proposed and studied by many researchers. In this paper, forming analysis of milli-components has been studied with a new micro-former. In modeling of progressive dies, multi-stage forming sequence has been analyzed with finite element analysis by LS-DYNA3D. The analysis proposes the sequential die and part shapes with the corresponding punch force and dimensional accuracy. The analysis also considers the effect of elastic dies on the dimensional accuracy of the formed parts. The analysis result demonstrates that the elastic analysis in the milli-forming process is indispensable fur accurate forming analysis. The analysis procedure in the paper will provide good information in design of a new micro-former and milli-component.

• 대한기계학회논문집A
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• 제21권5호
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• pp.842-849
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• 1997

The aim of this study is an investigation of the interaction of two micro hole defects affecting fatigue crack initation life and propagation behavior. The locatio of two micro hole defects was considered as an angle of alignment and the distance between the centers of two micro hole defects. The fatigue cracking behavior is experimented under bending. When micro defects are located close to each other, the fatigue crack initiation lives are varied with their relative locations. In the experiments, the area of local plastic strain strongly played a role in the fatigue crack initiation lives. Therefore we introduce a parameter which contains the plastic deformation area at stress concentrations and propose a fatigue crack initiation life prediction curve. In addition, the directions and propagation rates of fatigue cracks initiated at two micro hole defects are studied experimentally.

• 한국정밀공학회지
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• 제22권7호
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• pp.164-169
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• 2005

The micro-gripper system is one of the systems that should be improved in the respect of performance for practical usage. In the previous works, the important issues are considered and presented using axiomatic design approach. In this paper, the functional requirements and design parameters are evaluated in order to improve the performance and efficiency of the system. The evaluation is a very difficult task since many variables are related to the outcomes. To provide a basis for correct design decisions, axiomatic design principles have been advanced. Since the framework of axiomatic design makes design issues easier to understand when they are analyzed, we used those as an evaluation tool. The object of the system is to handle micro-size parts. Main device is a micro-gripper using two bender-typed and one stack-typed PZTs as actuators. And it has three tips made of tungsten wires fur holding function. Also the system must satisfy other functional requirements for appropriate handling performance. The results of this study show design improvements of micro-gripper system such as structural change of gripper, additional element, and integration of physical parts. Axiomatic design guides presented suitable design parameters corresponding to functional requirements and made the design elements improve through diagrams of whole system.

• 한국생산제조학회지
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• 제21권3호
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• pp.355-361
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• 2012

Though a micro pump is a crucial element in miniaturized bio-fluidic systems or drug delivery systems, it has some intrinsic disadvantages such as backward flow, pulsation of flow, low repeatability and producibility, and high cost. To overcome these limitation, a PZT disc actuated micro pump including a novel ring-shaped multi-flap check valve is introduced. To enhance the performance of the micro pump, the static behaviour of flap valve module and the micro fluidic behavior of fluids are numerically modelled and analyzed. As results of the numerical analysis, the optimal dimension and configuration of the ring-shaped multi flap valve are $1{\times}0.05$ mm and 2 (inlet side)${\times}1$ (outlet side) type. The obtained maximum flow rates and flow resolution are about 90 ml/min and 30 ${\mu}l$/stroke respectively.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.75-76
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• 2008

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.235.1-235
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• 2001

• 복합신소재구조학회 논문집
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• 제4권4호
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• pp.15-21
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• 2013

This study carried out finite element deflection analysis of cylindrical shell structures made of composite materials, which is based on the micro-mechanical approach for different fiber-volume fractions. The finite element (FE) models for composite structures using multi-scale approaches described in this paper is attractive not only because it shows excellent accuracy in analysis but also it shows the effect of the material combination. New results reported in this paper are focused on the significant effects of the fiber-volume fraction for various parameters, such as fiber angles, layup sequences, and length-thickness ratios. It may be concluded from this study that the combination effect of fiber and matrix, largely governing the dynamic characteristics of composite shell structures, should not be neglected and thus the optimal combination could be used to design such civil structures for better dynamic performance.

• 대한치과기공학회지
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• 제31권4호
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• pp.9-15
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• 2009

The purpose of this study was to observe the change of mechanical property and microstructure in porcelain fused to gold alloy by heat treatment. PFG alloys are composed with Au-Pd-Ag alloy of the additional elements with indium, tin and copper. Specimens were tested in hardness using vicker,s micro-hardness tester and the surface micro structural changes were analysed by SEM and EDS. The results were as fellows: 1. The vickers hardness showed highest in Au-Pd-Ag alloy of the additional element with tin. 2. By hardening-oxiding result, the vicker,s hardness increased in additional element with tin but there was no significant difference in additional elements with indium and copper. 3. The surface oxide layer of Au-Pd-Ag alloy with added indium and tin increased but there was small change in additional element with copper. 4. The elements of indium and tin increased with increasing heat treatment in the surface alloy.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1301-1302
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• 2008

In this study, the fracture strength for fracture mechanism porous calcium phosphate made from sintered with ${\beta}$-tricalcium phosphate obtained by wet precipitation procedure is analyzed using finite element method and experiment measurement. First, three $3{\times}3{\times}3mm^3$ and $5{\times}5{\times}5mm^3$ specimens are prepared and tomographic images of one $5{\times}5{\times}5mm^3$ specimen are obtained by micro focus X-ray CT. The compression tests using the specimens are carried out to measure the elastic modulus and fracture strength to analyze the fracture mechanism of porous calcium phosphate specimen. The tomographic images are reconstructed by 3D reconstruction program. The finite elements are directly built up in the reconstructed specimen. The numerical simulation for the compression tests is performed using the element. The mechanism of calcium phosphate of simulation are obtained by the compression tests using there cylindric specimen of height 19.5 mm and diameter 10 mm. From the results, the applicability of porous calcium phosphate is evaluated to care fracture and vacant bone of a patient as the reinforcement material.