• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.219-222
• /
• 2004

This research is about SDM (Structural Dynamics Modification) technique using embosses. SDM using embosses do not need to add additional mass element ana model of embosses and resulting huge calculation for getting analytical solution of an embossed structure. The object of this research is to suggest a method to guide placing embossment in a structure to raise its natural frequencies. Two methods to optimize model with embossing are suggested, indepuldently. The former is response surface analysis by neural network. And the latter is an indirect method using modal dynamic strain energy.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.1
• /
• pp.80-86
• /
• 2008

In this study. the noise sources were identified and the noise and vibration were reduced for an industrial forklift. To identify the noise sourses, noise signals were measured by a microphone on a driver seat and these signals were analyzed with a waterfall plot. For this purpose, the gear mesh frequencies from the gear box of a reducer were not only investigated but noise/vibration sourses of an electric motor were also examined. Furthermore, the frequency response functions were obtained to confirm the vibration and noise sourses. It was found that severe vibration and noise were generated in the casing and the connecting part of the reducer. The severe vibration and noise could be reduced by a structure modification.

• Journal of Ceramic Processing Research
• /
• v.20 no.1
• /
• pp.30-34
• /
• 2019

Copper (Cu)-incorporated silica aerogel was synthesized by a sol-gel process with two-step drying process for color modification. The microstructure of the silica aerogel was not affected significantly by the Cu concentration and an amorphous structure was maintained without any crystalline impurity phases. The textural properties of the silica aerogels investigated by using N2 adsorption-desorption isotherms exhibited the typical features of mesoporous materials. The pore size and porosity were not changed significantly even with the incorporation of Cu up to 1.5 M, which indicates negligible variation of thermal insulating properties. However, the color of the aerogel changed from white and light greenish to dark greenish with increasing Cu content. The color change of the silica aerogel was due to the modification of the electron energy band structure of silica by the Cu atomic levels. Therefore, the color of the silica aerogel powders could be manipulated by incorporating Cu without degrading the thermal insulating properties.

• Journal of the Korean Society for Heat Treatment
• /
• v.35 no.3
• /
• pp.150-158
• /
• 2022

The effects of scandium addition on the Al-6Si-2Cu Alloy were investigated. The Al-6Si-2Cu-Sc alloy was prepared by gravity die casting process. In this study, scandium was added at 0.2 wt%, 0.4 wt%, 0.8 wt%, and 1.0 wt%. The microstructure of Al-6Si-2Cu-Sc alloy was investigated using Optical Microscope, Field Emission Scanning Electron Microscope, Electron Back Scatter Diffraction, and Transmission Electron microscope. The microstructure of Al-6Si-2Cu alloy with scandium added changed from dendrite structure to equiaxed crystal structure in specimens of 0.4 wt% Sc or more, and coarse needle-shape eutectic Si and β-Al₅FeSi phases were segmented and refined. The nanosized Al₃Sc intermetallic compound was observed to be uniformly distributed in the modified Al matrix.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.1
• /
• pp.13-18
• /
• 2015

This study presents the structure design of antenna to have the dual band characteristics in a desired frequency band through the structural modification of an antenna structure. For the experiment, a wideband crossed planar monopole antenna was used. The target frequency band was set to ISM 2.45GHz/5.8GHz. To give the properties, an additional antenna element was added to the crossed planar monopole antenna, which is a main body of the antenna. And then structural adjustment parameter was set to change the length(shape) of the antenna. Various simulations were conducted to find the dual band characteristics in the desired frequency band. The simulations brought forth the antenna bandwidth above the normal values for ISM 2.45GHz/5.8GHz. The structural adjustment parameter introduced in this study for structural modification of an antenna can be useful in developing an antenna featured with dual band(multiband) characteristics.

• Journal of Aerospace System Engineering
• /
• v.17 no.4
• /
• pp.87-94
• /
• 2023

This paper addresses the installation and modification design of airframe structures for new and modified equipment installations that are essential for aircraft performance improvement. Typical performance improvement equipment mounted on the exterior of the aircraft include antenna, radar, electro-optical/infrared (EO/IR), and self-protection system equipment, which require structural reinforcement, modification, and mounting design of the green aircraft for operation. In the interior of the aircraft, console and rack structures are modified or added according to user operation requirements. In addition, this is accompanied by the installation design of equipment to be replaced and added for performance improvement, and the according modification of environmental control system components for internal cooling. The engineering process and cases in which airworthiness was verified through the detailed design of airframe structures with structural integrity, operability, and maintainability of performance-improved aircraft are presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.505-506
• /
• 2008

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2014.11a
• /
• pp.36-36
• /
• 2014

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 1999.05a
• /
• pp.71-72
• /
• 1999

• Bulletin of the Korean Chemical Society
• /
• v.33 no.11
• /
• pp.3899-3902
• /
• 2012