• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.4
• /
• pp.658-665
• /
• 2012

Micro-EDM is widely used in metallic pattern, electronics, nuclear power and industry in the form of precision process. The improvement of Electro Discharge Machining has been on a steady progress since $19^{th}$ century. The technology has overcome the limits of the traditional precision process, enabling micro-EDM, micro electrolytic machining, micro drilling, micro punching and laser beam machining, which create versatile products with smaller sizes. What have been known about the major feature of Micro-EDM is high thermal energy so that their products are free from the hardness of their products as long as they are electrical conductor. However, each metal is suspected to have different features and natures even if they are created through the same procedure. In this thesis, the methodology of Micro-EDM and how to categorize them are explained. Also, the nature of the examined materials with surface shape and surface roughnes are analyzed. The results of the experiments are expected to understand surface roughness and workability of other materials for Micro-EDM.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.4
• /
• pp.377-384
• /
• 2007

A backscatter Kikuchi diffraction attachment to an SEM enables the convenient investigation of grain orientations on bulk or micro surface. Their relation to micro structural features gives insight into many aspects of anisotropic materials properties. In micro area such as Micro Electro Mechanical Systems(MEMS) devices is required in order to improve understanding of how they may be expected to perform upon the micro scale. Electro Back Scatter Diffraction (EBSD) helps us to find uniform area as MEMS material. The ${\gamma}-TiAl$ has two different lamellar structures ${\gamma}/{\alpha}2-Ti_3Al$ phase which have shows $\{111\}{\gamma}//\{0001\}{\alpha}2$ plane indexing. The micro size testing specimen was successfully made by this structural relation. Interlamellar structure specimen averagely show $20{\sim}25%$ lower fracture toughness value compare with translamellar specimens Moreover micro fracture surface and micro crack progress were observed.

• The Journal of Asian Finance, Economics and Business
• /
• v.9 no.10
• /
• pp.179-188
• /
• 2022

Professional micro account officers create top-notch state-owned bank human resources using their knowledge, attitudes, characteristics, and talents. Therefore, it is vital to undertake study to ascertain how the performance of micro account officers will impact the personality and leadership style mediated through motivation. The goal of this study is to identify the mediated role of motivation (MOT) in the relationship between micro account officers' performance (citizenship behavior/CB) and leadership styles (LS) and personalities (BFP). Data was collected from 1.510 micro account officers of banks in Indonesia using the causal survey method to determine their citizenship behavior, leadership styles, personality, and role of motivation. The data collected was analyzed by structural equation modeling (SEM), with the result that leadership style, personality, motivation, leadership style, and personality have a significant effect on motivation and citizenship behavior. The interesting findings are related to the role of leadership style, micro account officer's personality, and citizenship behavior mediated by motivation. It was determined that micro account officers' enhanced performance (CB) was assigned by taking into account how their perceived superordinate leadership style, whether transformational direction or reversely by transactional propensity, and features of micro account officer including their personality, which was affected by five factors as well would then be well mediated by motivation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.976-979
• /
• 2002

This research presents the new method to fabricate small features through applying chemical mechanical micro machining(C3M) for Al5052 and single crystal silicon. To improve machinability of ductile and brittle material, reacted layer was formed on the surface before micro-drilling process by chemical reaction with $HNO_3$(10wt%) and KOH(10wt%). And then workpieces were machined to compare conventional micro-drilling process with newly suggested one. To evaluate whether or not the machinability was improved by the effect of chemical condition, surface defects such as burr, chipping and crack generation were measured. Finally, it is confirmed that C3M is one of the feasible tools for micro machining with the aid of effect of the chemical reaction.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.11
• /
• pp.45-51
• /
• 2008

Successive micro-scale V-grooves and a grid of pyramids were machined by elliptical vibration tufting (EVC) to investigate feasibility of using EVC as an alternative method of creating micro-molds to photo-lithography and electroforming, which have been commonly employed. An elliptical vibration grooving machine was developed which consists of two orthogonally-arranged piezoelectric actuators, a diamond cutting tool, and a motorized xyz stage. The micro-scale features were machined on materials of copper, duralumin, nickel, and hastelloy and it was found that EVC significantly reduces cutting resistance and prohibits generation of side burrs and rollover burrs, thus resulting in improving machining qualify of micro-molds in ail experimented workpiece materials.

• Journal of the Semiconductor & Display Technology
• /
• v.15 no.3
• /
• pp.6-11
• /
• 2016

Silicon wafer is one of main materials in solar cell. Micro-cracks in silicon wafer are one of reasons to decrease efficiency of energy transformation. They couldn't be observed by human eye. Also, their shape is not only various but also complicated. Accordingly, their shape classification is absolutely needed for manufacturing process quality and its feedback. The performance of typical classification techniques which is principal component analysis(PCA), neural network, fusion model to integrate PCA with neural network, and support vector machine(SVM), are evaluated using pattern features of micro-cracks. As a result, it has been confirmed that the SVM gives good results in micro-crack classification.

• The Journal of Korean Institute of Information Technology
• /
• v.17 no.6
• /
• pp.85-94
• /
• 2019

Warhead and debris show the different micro-Doppler frequency shape in the spectrogram because of the different micro motion. So we can classify them using the micro-Doppler features. In this paper, we classified warhead and debris in the separation phase using CNN(Convolutional Neural Networks). For the input image of CNN, we used micro-Doppler spectrogram. In addition, to improve classification performance of warhead and debris, we applied the preprocessing using CA-CFAR to the micro-Doppler spectrogram. As a result, when the preprocessing of micro-Doppler spectrogram was used, classification performance is improved in all signal-to-noise ratio(SNR).

• Nuclear Engineering and Technology
• /
• v.51 no.1
• /
• pp.1-12
• /
• 2019

One of proposed Accident Tolerant Fuel (ATF) concept is fully ceramic micro-encapsulated fuel (FCMF). FCMF using uranium mononitride (UN) has better safety aspects than $UO_2$ pellet fuel although it might not have a better neutronic performance due to the presence of matrix and high neutron-induced interaction of $^{14}N$. Before implementing UN-FCMF technology in Small-PWR, further research must be taken place to make sure the proposed design of fuel assembly has inherent safety features and maintain the fuel performance. This study focusses on the neutronic analysis of UN-FCMF based fuel assembly using Serpent and SCALE codes. It is shown in the proposed fuel assembly design has inherent safety features with respect to the fuel temperature reactivity coefficient, void reactivity coefficient, and moderator temperature reactivity coefficient. It is noted that the use of FCMF leads to a lower ratio of burnup to $^{235}U$ enrichment ratio compared to the $UO_2/Zr$ fuel.

• Journal of Mechanical Science and Technology
• /
• v.19 no.8
• /
• pp.1544-1553
• /
• 2005

In this article, a micro cantilever array actuated by PZT films is designed and fabricated for micro fluidic systems. The design features for maximizing tip deflections and minimizing fluid leakage are described. The governing equation of the composite PZT cantilever is derived and the actuating behavior predicted. The calculated value of the tip deflection was 15 ${\mu}m$ at 5 V. The fabrication process from SIMOX (Separation by oxygen ion implantation) wafer is presented in detail with the PZT film deposition process. The PZT films are characterized by investigating the ferroelectric properties, dielectric constant, and dielectric loss. Tip deflections of 12 ${\mu}m$ at 5 V are measured, which agreed well with the predicted value. The 18 ${\mu}l/s$ leakage rate of air was observed at a pressure difference of 1000 Pa. Micro cooler is introduced, and its possible application to micro compressor is discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.4
• /
• pp.14-20
• /
• 2015

Molding technologies for plastic microstructures have been extensively investigated during the last two decades, and theoretical and numerical studies on the micro molding process have provided efficient tools for the development of such molding technologies. In this paper, we present a review of numerical simulation methods for the micro molding process. Basic models for a description of the material property, governing equations of the flow and heat transfer during the molding process, and numerical methods will be described. Particularly, numerical simulations for micro injection molding and hot embossing processes will be presented, and their main features noted and compared to those for conventional molding processes.