• Proceedings of the Materials Research Society of Korea Conference
• /
• 2007.11a
• /
• pp.152.1-152.1
• /
• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.06a
• /
• pp.27-28
• /
• 2007

• Advances in materials Research
• /
• v.8 no.3
• /
• pp.219-235
• /
• 2019

This research is devoted to analyzing mechanical-thermal post-buckling behavior of a micro-size beam reinforced with graphene platelets (GPLs) based on geometric imperfection effects. Graphene platelets have three types of dispersion within the structure including uniform-type, linear-type and nonlinear-type. The micro-size beam is considered to be perfect (ideal) or imperfect. Buckling mode shape of the micro-size beam has been assumed as geometric imperfection. Modified couple stress theory has been used for describing scale-dependent character of the beam having micro dimension. Via an analytical procedure, post-buckling path of the micro-size beam has been derived. It will be demonstrated that nonlinear buckling characteristics of the micro-size beam are dependent on geometric imperfection amplitude, thermal loading, graphene distribution and couple stress effects.

• Journal of Electrical Engineering and Technology
• /
• v.7 no.1
• /
• pp.9-16
• /
• 2012

The present study presents the Phasor Discrete Particle Swarm Optimization (PDPSO) algorithm, an effective optimization technique, the multi-dimensional vectors of which consist of magnitudes and phase angles. PDPSO is employed in the configuration of micro-grids. Micro-grids are concepts of distribution system that directly unifies customers and distributed generations (DGs). Micro-grids could supply electric power to customers and conduct power transaction via a power market by operating economic dispatch of diverse cost functions through several DGs. If a large number of micro-grids exist in one distribution system, the algorithm needs to adjust the configuration of numerous micro-grids in order to supply electric power with minimum generation cost for all customers under the distribution system.

• Journal of Microbiology
• /
• v.43 no.4
• /
• pp.361-365
• /
• 2005

In this study, we chronicle the establishment of a novel transformation system for the unicellular marine green alga, Dunaliella salina. We introduced the CaMV35S promoter-GUS construct into D. salina with a PDS1000/He micro-particle bombardment system. Forty eight h after transformation, via histochemical staining, we observed the transient expression of GUS in D. salina cells which had been bombarded under rupture-disc pressures of 450 psi and 900 psi. We observed no GUS activity in either the negative or the blank controls. Our findings indicated that the micro-particle bombardment method constituted a feasible approach to the genetic transformation of D. salina. We also conducted tests of the cells' sensitivity to seven antibiotics and one herbicide, and our results suggested that 20 ${\mu}g$/ ml of Basta could inhibit cell growth completely. The bar gene, which encodes for phosphinothricin acetyltransferase and confers herbicide tolerance, was introduced into the cells via the above established method. The results of PCR and PCR-Southern blot analyses indicated that the gene was successfully integrated into the genome of the transformants.

• Journal of Mechanical Science and Technology
• /
• v.20 no.1
• /
• pp.85-93
• /
• 2006

The trend of miniaturization has been applied to the research of rockets to develop prototypes of micro rockets. In this paper, the development of a web-integrated prototyping system for three-dimensional micro rockets, and the results of combustion tests are discussed. The body of rocket was made of 6061 aluminum cylinder by lathe process. The three-dimensional micro nozzles were fabricated on the same aluminum by using micro endmills with ${\phi}100{\mu}m{sim}{\phi}500{\mu}m$ diameter. Two types of micro nozzle were fabricated and compared for performance. The total mass of the rockets was 7.32 g and that of propellant (gun powder) was 0.65 g. The thrust-to-weight ratio was between 1.58 and 1.74, and the flight test with 45 degree launch angle from the ground resulted in $46\;m{\sim}53\;m$ of horizontal flight distance. In addition, ABS housing for the micro machined rocket was fabricated using Fused Deposition Modeling (FDM). A web-based design, fabrication, and test system for micro nozzles was proposed to integrate the distributed hardware resources. Test data was sent to the designer via the same web server for the faster feedback to the rocket designer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05a
• /
• pp.197-201
• /
• 2002

This paper presents optimized design, fabrication and thermal characteristics of micro-heaters for thermal MEMS (micro electro mechanical system) applications using SOI and trench structures. The micro-heaters are based on a thermal measurement principle and contains thermal isolation regions of 10 ${\mu}m$-thick Si membranes consisting of oxide-filled trenches in the SOI membrane rim. The micro-heaters were fabricated with Pt-RTD on the same substrate via MgO buff layer between Pt thin-film and $SiO_2$ layer. The thermal characteristics of micro-heater with trench-free SOI membrane structure was $280^{\circ}C$ at input power 0.9 W; in the presence of 10 trenches, it was $580^{\circ}C$ due to reduction of the external thermal loss. Therefore, a micro-heater with trenches in SOI membrane rim structure provides a powerful and versatile alternative technology for enhancing the performance of micro-thermal sensors and actuators.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.3
• /
• pp.98-101
• /
• 2011

A 10 nm nano-silica was introduced to a conventional 3 ${\mu}M$ micro-silica composite to develop an eco-friendly new electric insulation material for heavy electric equipment. Thermal and mechanical properties, such as glass transition temperature (Tg), dynamic mechanical analysis, tensile and flexural strength, were studied. The mechanical results were estimated by comparing scale and shape parameters in Weibull statistical analysis. The thermal and mechanical properties of conventional epoxy/micro-silica composite were improved by the addition of nano-silica. This was due to the increment of the compaction via the even dispersion of the nano-silica among the micro-silica particles.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.6
• /
• pp.1455-1461
• /
• 2015

Micro Grid is a new concept of electrical grid to solve several problems of Mega-Grid and it is under research and development at the national level around the world. With this background, Micro Grid Common Platform has been developed for interoperability technology of devices-systems in Micro Grid and securing enabler for new market. For supporting business models, Micro Grid Common Platform provides electric power information to Third-Party licensee via Open API function. Licensee, who want to develop electric power application by connecting to Micro Grid Common Platform, needs IDE(Integrated Development Environment) for service development and distribution. The paper proposes a service development tool for developing applications of Micro Grid Common Platform as a PaaS (Platform as a Service).

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.8
• /
• pp.899-904
• /
• 2011

This This study aims to verify burr formation and to remove the burrs in micro-channel fabrication using micro-machining tools. The machining processes are combined with micro-milling and magnetic abrasive deburring for AISI316 stainless steel. Depending on the micro-milling conditions that are applied, burrs are formed around the side walls. Magnetic abrasive deburring is used to remove these burrs. AISI316 stainless steel is a nonferrous material and its magnetic flux density, which is an important parameter for efficient magnetic abrasive deburring, is low. To enhance this magnetic flux density, we design and build a magnetic array table. The effect of removing burrs is evaluated via SEM and a surface tester.