• 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.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.812-815
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• 2004

The molecular structure influences the thermal behavior of HTM. For OLED the glass transition temperature and evaporation temperature are critical. We report how changes in structure cause changes on both parameters. The results may be of interest for chemists when they design new molecule structures for OLED.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.3
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• pp.260-270
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• 2011

The electromechanical impedance(E/M)-based method detects local structural damages based on variations of electrical impedance signatures which are obtained from piezoelectric sensors bonded to the structure and excited in high frequency band. In this method, temperature changes may result in significant impedance variations and lead to erroneous diagnostic results of the structure. To tackle this problem, a new technique providing a 2-dimensional damage feature related to the temperature information is proposed to distinguish the structural damage from the undesirable temperature variation. For experimental tests to validate the proposed method, damages are introduced by bolt loosening to a bolt-jointed steel beam, and impedance signals are measured under varying temperature conditions through a piezoelectric sensor attached on the beam. A freely suspended piezoelectric sensor is additionally utilized to obtain temperature information indirectly from resistance signatures. From a relationship between the damage index (from a constrained sensor) and the temperature (from a freely suspended sensor or a temperature sensor), damages can be detected more clearly under varying temperature compared to other conventional approaches.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.345-349
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• 2000

Activated carbons were prepared from Korean coal by steam activation in this study. The variation of pore structure of the activated carbons were investigated according to different carbonization temperatures. Yield, surface area, pore volume and pore structure of this activated carbon were compared with those of activated carbon prepared without carbonization. The investigated carbonization temperature ranged from 700${\circ}C$ to 1,000${\circ}C$. Carbonization was carried out in nitrogen atmosphere for 70 minutes and activation was performed by steam at 950${\circ}C$ for 210 minutes. Surface area and pore volume of the resulting activated carbons increased with carbonization temperature. Also pore volume increased by 20% compared to the activated carbon without carbonization. Especially, in mesopore region, the activated carbon carbonized at 900${\circ}C$ had more pores by 60% than that of activated carbon carbonized at other temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.73-78
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• 2003

The influence of calcination temperature on the pore structure of freeze dried silica gel derived from tetraethyl orthosilicate (TEOS) was investigated using $N_2$adsorption and mercury intrusion techniques. Freeze dried material contained not only 4-6 nm sized mesopores and 6-10 $\mu\textrm{m}$ sized macropores, but minor micropores. The change of pore structure due to the increase of calcination temperature was dependant upon the degree of densification.

• Electrical & Electronic Materials
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• v.7 no.1
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• pp.49-56
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• 1994

Polycrystalline CdS thin films were deposited by using EBE method and its crystal structure, surface morphology, electrical and optical properties as a function of annealing temperature were investigated. It was found that optimum growth conditions were substrate temperature annealing temperature 300[.deg. C]. The films were hexagonal structure preferred(002) plane and maximum grain size was 421[.angs.]. As the results, resistivity and optical transmittance of CdS thin films were $8.3{\times}{10^3}$[.ohm.cm] and 89[%] respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.149-149
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• 2000

Alkali and alkali-earth metal on si(001) surface has been investigated widly for both scientific and technological aspects. In particular, the Ba/Si(001) system has been studied by several groups and they reported many phases such as (2$\times$3), (2$\times$4) and c(6$\times$2) 표 LEED and AES for various temperature and coverages. But there has not been the result of the atomic structure for these phases. Recently some works about the atomic structure of Ba/Si(001) at only room temperature were presented. In this study, we investigated 3-dimensional atomic structure and growth mode of Ba layer on si(001) by coaxial impact collision ion scattering spectroscopy (CAISS) at room temperature and high temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.147-148
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• 2020

In case of high temperature damage such as fire, the durability of concrete is reduced due to the collapse of internal pore tissue. Therefore, in this paper, we are going to analyze the pore structure of cement paste hardening agent using MIP analysis and build up 3D data produced using X-ray CT tomography. The test specimen is made of cement paste from W/C 0.4. As the temperature of heating increased, the amount of air gap and the diameter of air gap in cement paste increased. It is judged that the air gap structure inside cement collapsed due to the evaporation of the hydrate, gel count, capillary water, etc. inside the cement due to the high temperature.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.185-191
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• 2003

This paper presents the thermal problems of steel-concrete composite structure and the basic references in placing concrete into the structure. Based on the analytical investigation, application of the composite structure has the effect of highly decreasing the temperature difference between the center section and the surface section of the structure, though its application has little influence on the decrement of the maximum temperature under the same using material and placing temperature. Meanwhile, its application causes the section decrement of a concrete structure, and in the section which the decrement ratio is relatively large, the restraint action by a old concrete structure takes place highly tensile stresses over a tensile strength. And, the stress is concentrated on sharp edges of the steel-concrete boundary. Both restraint action and stress concentration considerably decrease the reduction effect of the temperature difference. Therefore, the prediction of thermal response and the reasonable steps are required through the simulation considering the factors and the sections related to those problems.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1661-1668
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• 1990

In a turbulent premixed flame stabilized by the streamline step, and dominated by a coherent eddy, a flame micro-structure was investigated with analyzing the signals of temperature, the ion current, and schieren phtographs simultaneously. Generally the contours of large scale coherent eddies of schlieren photographs was considered as the flame front, however, the main reaction can be occurred within the eddy as a structure of fine flamelets scale. The surrounding burned gas of flamelets could not propagate to a unburned mixture, obstructing flamelets from propagating to a unburned mixture. Consequently, it could restrain flashback. The main reaction region was found to be located at higher temperature of the burned gas rather than at maximum rms of fluctuating temperature. The peak probability of higher temperature was 6 times greater than that of lower temperature. As it was difficult to infer a flame structure from PDF distribution of the fluctuating temperature in form of bimodal shape, it should be taken into consideration with other informations related to the sensitive flame front, for instance, ion current.