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강석호,장주혜,손호현 대한치과보존학회 2013 Restorative Dentistry & Endodontics Vol.38 No.3
Objectives: There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass), and to observe their crystalline structures. Materials and Methods: Biaxial flexural strength was tested according to ISO 6872with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi) and x-ray diffraction (XRD, Rigaku) analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05. Results: There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05). The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis,they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment. Conclusions: IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition. (Restor Dent Endod 2013;38(3):134-140)
姜錫浩 嶺南大學校 工業技術硏究所 1976 연구보고 Vol.4 No.1
To regenerate the pelletized active carbon used in the waste water treatment, a vertical tubular furnace of 80cm. in length and of 3.5cm. in core diameter was designed to combust propane gas as heat source. Prior to the operation, it is desired to estimate the attainable temperature of the furnace. By means of a simple computer program with the aid of conventional energy-balance method, the temperature of the flue gas was estimated by varying the propane feed rate and the excess air ratio. Compared with the economic velocity of the gas flow, the propane gas feed rate may be limited under the trasition flow rate of the flue gas produced. The estimation was tried on the assumption that the steady-state heat transfer through the funace wall is kept and the temperatures of both sides of the inlet and the exit are nearly uniform throughout.
강석호 嶺南大學校 工業技術硏究所 1988 연구보고 Vol.16 No.1
The commercially available nonwoven fibrous filter mats are used to collect the CaCO₃sample dust from the air stream. The collection efficiency and the grade efficiency in the air filtration are experimentally determined and compared with the analogous results calculated by the theoretical equations proposed by other researchers. The pressure drop measured across the filter mat is also discussed with the theoretically estimated one. The comparison between the two results are in a good agreement with each other. Effects of the fibre diameter and the inlet air velocity on the separation efficiency and on the pressure drop are also discussed.
二次元 畵面解析을 이용한 三次元空間의 固體粒子 濃度 測定範圍
강석호 嶺南大學校 工業技術硏究所 1982 연구보고 Vol.10 No.2
Optical measurements of particle size, its distribution, concentration, and velocity in the particulate handling processes are of great significance in recent years. The 2-dimensional optical images observed provide, with little precision, the particle characteristics in the 3-dimensional space of the volume element, in which the particle concentratioin plays a remarkable role in data acquisition of particle size concerned. Geometrical relationships between the 3-dimensional volume concentration and the 2-dimensional photographic obscuration are mathematically discussed, and the concentration criteria of the possible observation range to be applicable in particle characterization are experimentally determined. Above 5% of particle concentration in volume, the photographic images do not provide any sufficient results in the particle size measurement by the optical method.