• Carbon letters
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• v.10 no.3
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• pp.181-189
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• 2009

Activated carbon spheres (ACS) were prepared at different heating rates by carbonization of the resole-type phenolic beads (PB) at $950^{\circ}C$ in $N_2$ atmosphere followed by activation of the resultant char at different temperatures for 5 h in $CO_2$ atmosphere. Influence of heating rate on porosity and temperature on carbon structure and porosity of ACS were investigated. Effect of heating rate and temperature on porosity of ACS was also studied from adsorption isotherms of nitrogen at 77 K using BET method. The results revealed that ACS have exhibited a BET surface area and pore volume greater than $2260\;m^2/g$ and $1.63\;cm^3/g$ respectively. The structural characteristics variation of ACS with different temperature was studied using Raman spectroscopy. The results exhibited that amount of disorganized carbon affects both the pore structure and adsorption properties of ACS. ACS were also evaluated for structural information using Fourier Transform Infrared (FTIR) Spectroscopy. ACS were evaluated for chemical composition using CHNS analysis. The ACS prepared different temperatures became more carbonaceous material compared to carbonized material. ACS have possessed well-developed pores structure which were verified by Scanning Electron Microscopy (SEM). SEM micrographs also exhibited that ACS have possessed well-developed micro- and meso-pores structure and the pore size of ACS increased with increasing activation temperature.

• Food Science and Biotechnology
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• v.18 no.3
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• pp.717-723
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• 2009

Thermal degradation characteristics of sucrose was investigated. A 20% sucrose solution was heated to temperatures of $110-150^{\circ}C$ for 1-5 hr. Chromaticity, pH, organic acids, 5-hydroxymethylfurfural (HMF), free sugars, electron donating ability (EDA), and ascorbic acid equivalent antioxidant capacity (AEAC) of the heated sucrose solutions were evaluated. With increasing temperatures and times, the L-, a-, and b-values decreased; however, total color difference (${\Delta}E_{ab}$) increased. The pH and sucrose contents decreased, and fructose and glucose contents increased with increasing heating temperature and time. Organic acids, such as formic acid, lactic acid, and levulinic acid, and HMF contents increased with increasing heating temperatures and times. EDA (%) and the AEAC of the heated sucrose solutions increased with increasing heating temperature and time. The heated sucrose solution was more effective than unheated sucrose solution, having higher EDA (90 fold), and AEAC (13 fold).

• Korean Journal of Metals and Materials
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• v.48 no.2
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• pp.141-147
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• 2010

An Ni-Al intermetallic coating has been produced by induction heating on mild steel. The effect of the induction heating conditions on the microstructure of the coating has been investigated. The reaction synthesis of the intermetallic compounds was promoted while increasing the heating rate and the holding time at reaction temperature. Especially, an NiAl phase corresponding to the initial composition of mixed powder was predominantly formed. However, the synthesis at low reaction temperatures occurred by solid state diffusion during the holding time and an Fe-Al reaction layer was formed at the interface with the substrate, regardless of the heating rate. The combustion synthesis of the intermetallic compound occurred at a temperature higher than 1023 K and resulted in an almost single phase NiAl structure.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.746-751
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• 2002

In order to make clear the physical relation among the arc plasma, the anode heat transfer and the weld penetration, the results of experimental measurements of temperatures of arc plasma, the distributions of heat input and current on the anode and the weld penetration were presented The experimental results showed that the electron temperature above the anode and current and heat input density on the anode was dominated by the position of the cathode. Furthermore, it was showed that electron temperature of arc plasma was dominated by the cathode shape. These results were related with the results of the welded penetration measurements. As a result, it was showed that the electron temperature above the anode and current density distribution on the anode decided the heat input density distribution on the anode and that the heat input density on the anode remarkably dominated the size of the weld penetration in argon GTA welding process. Furthermore, it was suggested that the cathode played the important role in the determination of the weld penetration in argon GTA welding process.

• Applied Microscopy
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• v.45 no.4
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• pp.199-202
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• 2015

A simple and novel transmission electron microscopy (TEM) sample preparation method for phase change nanowire is investigated. A $Ge_2Sb_2Te_5$ (GST) nanowire TEM sample was meticulously prepared using nanomanipulator and gas injection system in a field emission scanning electron microscopy for efficient and accurate TEM analysis. The process can minimize the damage during the TEM sample preparation of the nanowires, thus enabling the crystallographic analysis of as-grown GST nanowires without unexpected phase transition caused by e-beam heating.

• Applied Microscopy
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• v.34 no.1
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• pp.23-29
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• 2004

In this study, we introduce the structural analysis of amorphous silica nanoparticles by EF-TEM electron diffraction and in-situ heating experiments. Three diffused rings were observed on the electron diffraction patterns of initial silica nanoparticles, while crystalline spot patterns were gradually appeared during the insitu heating process at $900^{\circ}C$. These patterns indicate the basic unit of $SiO_4$ tetrahedra consisting amorphous silica and gradual crystallization into the ideal layer structure of tridymite by heating. Under high vacuum condition in TEM, SiO nanoparticles were redeposited on the carbon grid after evaporation of SiO gas from $SiO_2$ above $850^{\circ}C$ and the remaining $SiO_2$ were crystallized into orthorhombic tridymite, consistent with ex-situ heating results in furnace at $900^{\circ}C$.

• Applied Microscopy
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• v.47 no.3
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• pp.208-213
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• 2017

The microstructural changes in Co nanoparticles and an Au-10at.%Pd thin film have been investigated using an in situ heating holder with a micro-electro-mechanical system (MEMS). In Co nanoparticles, two phases (face-centered cubic and hexagonal close-packed crystal structures) were found to coexist at room temperature and microstructures at temperatures, higher than $1,000^{\circ}C$, were observed with a quick response time and significant stability. The actual temperature of each specimen was directly estimated from the changes in the lattice spacing (Bragg-peak separation). For the Au-10at.%Pd thin film, at a set temperature of $680^{\circ}C$, the actual temperature of the sample was estimated to be $1,020^{\circ}C{\pm}123^{\circ}C$. Note that the specimen temperature should be carefully evaluated because of the undesired effects, i.e., the temperature non-uniformity due to the sample design of the MEMS chip, and distortion due to thermal expansion.

• Korean Journal of Digital Imaging in Medicine
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• v.12 no.2
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• pp.145-150
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• 2010

Thick films of carbon fiber were prepared by a heating element of plan shape made in Darin co., We have investigated surface morphology of the specimen depending on heat-treatment temperatures. Scanning electron microscope(SEM) image of carbon fiber thick films of the specimen heat treated shows a grain growth at $1200^{\circ}C$ and becomes a poly-crystallization at $1350^{\circ}C$. The variation of resistivity at the thermally annealed specimen above $600^{\circ}C$ depends on type of the substrates. It may be due to a variation of film thickness and a difference of interfacial phenomena. A heating element of features was affected significantly by skin blood and quantity of heat of the body physiological function. After radiation of farinfrared for plate heating element, the function of biometric physiological is considered of skin blood flow and calorie which greatly affects on individuals. Electromagnetic wave was not influence on the body.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.239.2-239.2
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• 2015

Graphene is a most interesting material due to its unique and outstanding properties. However, semi-metallic properties of graphene along with zero bandgap energy structure limit further application to optoelectronic devices. Recently, many researchers have shown that band gap can be induced in the Bernal stacked bilayer graphene. Several methods have been used for the controlled growth of the Bernal staked bilayer graphene, but it is still challenging to control the growth process. In this paper, we synthesize the large area Bernal stacked bilayer graphene using multi heating zone low pressure chemical vapor deposition (LPCVD). The synthesized bilayer graphenes are characterized by Raman spectroscopy, optical microscope (OM), scanning electron microscopy (SEM). High resolution transmission electron microscopy (HRTEM) is used for the observation of atomic resolution image of the graphene layers.

• Journal of Astronomy and Space Sciences
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• v.5 no.1
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• pp.1-8
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• 1988

Electron beam propagation in a fully ionized plasma has been studied using a one-dimensional particle simulation model. We compare the results of electrostatic simulations to those of electromagnetic simulations. The electrostatic results show the essential features of beam-plasma interactions. It is found that the return currents are enhanced by the beam-plasma instability which accelerates ambinet plasmas. The results also show the heating of ambient plasmas and the trapping of plasmas due to the locally generated electric field. The electromagnetic simulations show much the same results as the electrostatic simulations do. The level of the radiation generated by the same non-relativistic beam is slightly higher than the noise level. We discuss the results in context in context of the heating of coronal plasma during solar flares.