• Journal of Periodontal and Implant Science
• /
• v.41 no.5
• /
• pp.218-226
• /
• 2011

Purpose: Micro-computed tomography (micro-CT) has been widely used in the evaluation of regenerated bone tissue but the reliability of micro-CT has not yet been established. This study evaluated the correlation between histomorphometric analysis and micro-CT analysis in performing new bone formation measurement. Methods: Critical-size calvarial defects were created using a 8 mm trephine bur in a total of 24 Sprague-Dawley rats, and collagen gel mixed with autogenous rat bone marrow stromal cells (BMSCs) or autogenous rat BMSCs transduced by adenovirus containing bone morphogenic protein-2 (BMP-2) genes was loaded into the defect site. In the control group, collagen gel alone was loaded into the defect. After 2 and 4 weeks, the animals were euthanized and calvaria containing defects were harvested. Micro-CT analysis and histomorphometric analysis of each sample were accomplished and the statistical evaluation about the correlation between both analyses was performed. Results: New bone formation of the BMP-2 group was greater than that of the other groups at 2 and 4 weeks in both histomorphometric analysis and micro-CT analysis (P=0.026, P=0.034). Histomorphometric analysis of representative sections showed similar results to histomorphometric analysis with a mean value of 3 sections. Measurement of new bone formation was highly correlated between histomorphometric analysis and micro-CT analysis, especially at the low lower threshold level at 2 weeks (adjusted $r^2=0.907$, P<0.001). New bone formation of the BMP-2 group analyzed by micro-CT tended to decline sharply with an increasing lower threshold level, and it was statistically significant (P<0.001). Conclusions: Both histomorphometric analysis and micro-CT analysis were valid methods for measurement of the new bone in rat calvarial defects and the ability to detect the new bone in micro-CT analysis was highly influenced by the threshold level in the BMP-2 group at early stage.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.2
• /
• pp.154-161
• /
• 1995

In order to analysis of the stress distribution around flaws and the interaction effects between fatigue cracks, stress around micro hole was analyzed by Finite Element Method(F.E.M.) and micro hole specimens were tested using rotary bending fatigue machine and twisting fatigue machine to identify stress effects for fatigue cracks initiating from micro holes and interaction effects between micro holes. The results are as follows : Interaction effects of .sigma. $_{y}$for the micro hole side is larger than the large micro hole side when the interval between micro holes is near. Stress concentration factor increase as the diameter of micro hole becomes smaller. But, stress field of micro hole is smaller than that of large micro hole at h .leq. r (h:depth of micro hole, r:radius of micro hole) and that of large hole is larger than that of small micro hole at h >r expect the small range from micro hole.e.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1927-1931
• /
• 2003

Nanometer-sized structures are being applied to many fields including micro/nano electronics, optoelectronics, quantum computing, biosensors, etc. Micro contact printing is one of the most promising methods for manufacturing the nanometer-sized structures. The crucial element for the micro contact printing is the nano-resolution printing technique using polymeric stamps. In this study, a multi-scale analysis scheme for simulating the micro contact printing process is proposed and some useful analysis results are presented. Using the slip-link model [1], the dependency of viscoelasticity on molecular weight of polymer stamp is predicted. Deformation behaviors of polymeric stamps are analyzed using finite element method based upon the predicted viscoelastic properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.1
• /
• pp.85-92
• /
• 2002

In this study, we analyzed and experimented micro-strip line inductors and capacitors for a SAW duplexer, an important devise for mobile communication. For SAW duplexers, micro-strip line lumped elements must have small impedance values, below several tens of nH or several tens of pF, and a small area pattern. In this study, we performed theoretical analysis of flat line type, meander line type, and spiral line type inductors and interdigital capacitors on a LiTaO$_3$ Piezo-crystal. We proposed a measurement method to evaluate small values of lumped elements accurately with network analyzer. In experiments, we confirmed validity of the theoretical analysis method through fabrication and characterization of micro-strip line lumped elements. The analysis method in this paper can be applied to SAW duplexers well as other microwave devices.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.11
• /
• pp.2175-2184
• /
• 2009

This paper describes operational analysis results of the DC micro-grid using detailed model of distributed generation. Detailed model of wind power generation, photo-voltaic generation, fuel-cell generation was implemented with the user-defined model of PSCAD/EMTDC software that is coded with C-language. The operation analysis was carried out using PSCAD/EMTDC software, in which the power circuit is implemented by built-in model and the controller is modelled by user-defined model that is also coded with C-language. Various simulation results confirm that the DC micro-grid can operate without any problem in both the interconnected mode and the islanded mode. The operation analysis result confirms that the DC micro-grid make it feasible to provide power to the load stably. And it can be utilize to develop the actual system design and building.

• Journal of Sensor Science and Technology
• /
• v.21 no.5
• /
• pp.319-323
• /
• 2012

In this paper, we present the possibility of quantification analysis for $A{\beta}$ captured by micro beads using Near-filed detection. In order to evaluate detection efficiency, detected signals were compared with different sizes of micro beads and a varied number of micro beads. Also, $A{\beta}$ deposits and $A{\beta}$ binding to micro beads were measured, therefore, we observed the $A{\beta}$ deposit and light scattering around the surface of micro beads induced by attached $A{\beta}$. This method can be used for quantitative analysis for not only the number of $A{\beta}$, but also the binding ratio of $A{\beta}$ to micro beads.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.1045-1048
• /
• 2002

Micromachines are extremely novel artifacts with a variety of special characteristics. Utilizing their tiny dimensions ranging roughly from 10 to $1O^3$ micro-meters, the micromachines can perform tasks in a revolutionary manner that would be impossible for conventional artifacts. Micromachines are in general related to various coupled physical phenomena. They are required to be evaluated and designed considering the coupled phenomena. This paper describes finite element analysis (FEA) simulation of practical behaviors for the micro actuator. Especially, electric field modeling in micro actuators has been generally restricted to in-plane two-dimensional finite element analysis because of the complexity of the micro actuator geometry. However, in this thesis, the actual three-dimensional geometry of the micro actuator is considered. The starting torque obtained from the in-plane two-dimensional analytical solutions were compared with that of the actual three-dimensional FE analysis results. The starting torque is proportional to $V^2$, and that the two-dimensional analytical solutions are larger than the three-dimensional FE ones. It is found that the evaluation of micro actuator has to be considered electrical leakage phenomenon.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.3
• /
• pp.408-414
• /
• 2012

Screen printing is a printing method that uses a woven mesh to support an ink-blocking stencil by transferring ink or other printable materials in order to form an image onto a substrate. Recently, the screen printing method has applied to micro-electronic packaging by using solder paste as a printable material. For the screen printing of solder paste, metal masks containing a number of micro-holes are used as a stencil material. The metal mask undergoes deformation when it is installed in the screen printing machine, which results in the deformation of micro-holes. In the present study, finite element (FE) analysis was performed to predict the amount of deformation of a metal mask. For an efficient calculation of the micro-holes of the metal mask, the sub-domain analysis method was applied to perform FE analyses connecting the global domain (the metal mask) and the local domain (micro-holes). The FE analyses were then performed to evaluate the effects of slot designs on the deformation characteristics, from which more uniform and adjustable deformation of the metal mask can be obtained.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.18 no.3
• /
• pp.294-299
• /
• 2009

Micro end-milling has been becoming an important machining process to manufacture a number of small products such as micro-devices, bio-chips, micro-patterns and so on. Many related researches have given grand effects to micro end-milling phenomenon, for example, micro end-milling mechanism, cutting force modeling and machinability. This paper strongly concerned actual problem, micro tool deflection, which causes excessive machining errors on the workpiece. Machining error were predicted and measured through a series of test micro cutting and analysis of their SEM images and FEM analysis. Experiments are carried out to validate the approaches.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.3
• /
• pp.44-49
• /
• 2007

Recent manufacturing system requires development on new production technology to enable prompt manufacturing of diverse products. Most of the researchers have been working on micro-factory. Especially, focus on manufacturing of micro parts. Present manufacturing system consumes excessive resources in the form of energy and space to manufacture the micro parts. In this study, the micro lens module assembly system was modeled, analyzed with MST(Micro System Technology) Application Module and simulated through UML Language (Unified Modeling Language) with object-oriented logical model analysis method. Digital model of micro-factory was modeled, to execute the new paradigm of digitalization on products, resources and processes of micro-factory.