• Proceedings of the KIPE Conference
• /
• 2006.06a
• /
• pp.532-533
• /
• 2006

In this research work attempts were made to study the bonding of thermoplastics with adhesives using solar energy. In order to study the curing behaviour necessary experiments were conducted under varying conditions of temperature, exposure time and power. The cured samples were then studied under the optical microscope before subjecting to tensile testing in order to study their mechanical properties. The fracture surfaces were further studied under the Scanning Electron Microscopy in order to study the microstructural changes that are taken place during curing. From the present study it is evident that curing under higher solar energy temperature, generally improves bond strength and quality of the adhesive joints when compared to other modes of curing process expect the microwave curing process.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2012.11a
• /
• pp.175-177
• /
• 2012

A corrosion resistance and hard nitrocarburized layer was distinctly formed on 310 austenitic stainless steel substrate by DC plasma nitrocarburizing. Basically, 310L austenitic stainless steel has high chromium and nickel content which is applicable for high temperature applications. In this experiment, plasma nitrocarburizing was performed in a D.C. pulsed plasma ion nitriding system at different temperatures in $H_2-N_2-CH_4$ gas mixtures. After the experiment structural phases, micro-hardness and corrosion resistance were investigated by the optical microscopy, X-ray diffraction, scanning electron microscopy, micro-hardness testing and Potentiodynamic polarization tests. The hardness of the samples was measured by using a Vickers micro hardness tester with the load of 100 g. XRD indicated a single expanded austenite phase was formed at all treatment temperatures. Such a nitrogen and carbon supersaturated layer is precipitation free and possesses a high hardness and good corrosion resistance.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.4
• /
• pp.527-533
• /
• 1990

Zone-melting recrystallization (ZMR) system using two graphite heaters(a stationary sheet and a narrow movable bar) was constructed and implemented in recrystallization op Si films on insulating layers. The recystallized Si films were examined by Nomarski contrast optical microscopy after Dash etching, transmission electron diffraction pattern, and x-ray diffraction. With optimum conditions of process parameters(input powers of the bottom and upper heater, scanning speed of the upper heater, and the gap between sample and upper heater), the recrystallized Si layer has a (100) texture, but contains many subboundaries. The subgrains are misoriented by < 0.5\ulcorner and the average spacing between subboundaries is about 25\ulcorner.

• Journal of Environmental Science International
• /
• v.14 no.8
• /
• pp.761-770
• /
• 2005

Scanning electron microscopy / energy dispersive X-ray analyzer(SEM/EDX) has played an important role for evaluation the source of atmospheric particle because it is a powerful tool for characterizing individual particles. The SEM/EDX system provides various physical parameters like optical diameter, as well as chemical information for a particle-by-particle basis. The purpose of the study was to classify individual particle emitted from the point sources based on clustering analysis and physico-chemical analysis by SEM/EDX. The total of 490 individual particle were analyzed at 8 point sources including coal-fired power plant, incinerator, H-C oil boiler, and metal manufacturing industry. The main components were Si and AI in the coal-fired power plant, Cl and Na in the domestic waste Incinerator, S in the H-C oil boiler and S and Fe in the metal manufactory industry, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.403-404
• /
• 2008

In this study, we prepared ITO thin film on glass, polycarbonate (PC) and polyethersulfone (PES) substrate in Facing Targets sputtering (FTS) system. Properties of as-deposited thin films's aging change were investigated as a function of time placed in the air. The electrical and optical properties of as-deposited thin films were employed by a four point probe and an UV/VIS spectrometer, an X-ray diffractometer (XRD), a Field Emission Scanning Electron Microscope(FESEM) and a Hall Effect measurement. As a result, as time went by, transmittance of all films did not change but resistivity of films was decreasing.

• Journal of the Korean Ceramic Society
• /
• v.37 no.8
• /
• pp.768-773
• /
• 2000

Alnite clinker, which is based on CaO-SiO2-CaCl2 system, was synthesized by recycling Cl-containing waste, and its hydraulic properties were onvestigated. Alinite coinkers with two different chemical compositions were burned for 10∼30 minutes in the range of temperature, 1350∼1450$^{\circ}C$. The microstructures of those clinkers were characterized by powder X-ray diiffracuion analysis, optical microscope, and scanning electronic microscope and heat of hydration of alinite cements which was measured in order to investigate hydraulic properties. X-ray analysis shwoed that f-CaO in both clinkers with different compositions significantly was decreased with transforming C2S(belite) to C3S(alite). From the results of microscopy and scanning electron microscopy(SEM), crystal of synthesized alite(C3S) was larger and better crystallinity than that of ordinary portland cement.

• Journal of the Korean Magnetic Resonance Society
• /
• v.24 no.1
• /
• pp.16-22
• /
• 2020

Based on quantum transport theory, we investigated theoretically the magnetic field dependence of the quantum optical transition of quasi 2-dimensional Landau splitting system, in CdS and ZnO Through the analysis of the current work, we found the increasing properties of the cyclotron resonance line-profiles (CRLPs) which show the absorption power and the cyclotron resonance line-widths (CRLWs) with the magnetic field in CdS and ZnO We also found that that CRLWs, γ_total(B) of CdS < γ_total(B) of ZnO in the magnetic field region B < 15 Tesla.

• Electronics and Telecommunications Trends
• /
• v.33 no.6
• /
• pp.34-40
• /
• 2018

Traditionally, many researchers have conducted research on terahertz technology utilizing optical devices such as lasers. However, nanometer-scale electronic devices using silicon or III-V compound semiconductors have received significant attention regarding the development of a terahertz system owing to the rapid scaling down of devices. This enables an operating frequency of up to approximately 0.5 THz for silicon, and approximately 1 THz for III-V devices. This article reviews the recent trends of terahertz monolithic integrated circuits based on several electronic devices such as CMOS, SiGe BiCMOS, and InP HBT/HEMT, and a particular quantum device, an RTD.

• Journal of the Korean Society for Heat Treatment
• /
• v.32 no.5
• /
• pp.195-200
• /
• 2019

For expanding the applications and workability of TiAl alloy, elongation is very important property. Fine microstructure is needed for elongation and physical properties of TiAl alloys. In this study, The effects of cyclic heat treatment process for fine microstructure of Ti-46Al-Nb-W-Cr-Si-C alloy, which was made by VAR (vacuum arc remelting) and VIM(vacuum induction melting) centrifugal casting process, was investigated. Cycle heat treatment process was very effective for recrystallization of this TiAl system, which has microstructure size of $50{\sim}100{\mu}m$ through pre-heat treatment, cyclic heat treatment in ${\alpha}+{\gamma}$ phase region and solution heat treatment respectively. Refined grain size was finally confirmed by photos of optical microscope and scanning electron microscope.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.6
• /
• pp.1169-1174
• /
• 2011

CdTe thin-film solar cell technology is well known that it can theoretically improve its conversion efficiency and manufacturing costs compared to the conventional silicon solar cell technology, due to its optical band gap energy (about 1.45eV) for solar energy absorption, high light absorption capability and low cost requirements for producing solar cells. Although the prior studies obtained the high light absorption, CdTe thin film solar cell has not been come up to the sufficient efficiency yet. So, doping method was selected for the improvement of the electrical characteristics in CdTe solar cells. Some elements including Cu, Ag, Cd and Te were generally used for the p-dopant as substitutional acceptors in CdTe thin film. In this study, the sputtering-deposited CdTe thin film was immersed in $AgNO_3$ solution for ion exchange method to dope Ag ions. The effects of immersion temperature and Ag-concentration were investigated on the optical properties and electrical characteristics of CdTe thin film by using Auger electron spectroscopy depth-profile, UV-visible spectrophotometer, and a Hall effect measurement system. The best optical and electrical characteristics were sucessfully obtained by Ag doping at high temperature and concentration. The larger and more uniform diffusion of Ag ions made increase of the Ag ion density in CdTe thin film to decrease the series resistance as well as mede the faster diffusion of light by the metal ions to enhance the light absorption.