• Applied Microscopy
• /
• v.45 no.3
• /
• pp.177-182
• /
• 2015

The boiler tubes of X20CrMoV12.1 used in fossil-fired power plants were obtained and analyzed for the effect of water treatment on the steam corrosion-induced oxide scale in an effort to better understand the oxide formation mechanism, as well as pertinent method of maintenance and lifetime extension. The specimens were analyzed using various microscopy and microanalysis techniques, with focuses on the effect of water treatment on the characters of scale. X-ray diffraction analysis showed that the scales of specimens were composed of hematite ($Fe_2O_3$), magnetite ($Fe_3O_4$), and chromite ($FeCr_2O_4$). Electron backscatter diffraction analysis showed that the oxides were present in the following order on the matrix: outer $Fe_2O_3$, intermediate $Fe_3O_4$, and inner $FeCr_2O_4$. After all volatile treatment or oxygenated treatment, a dense protective $Fe_2O_3$ layer was formed on the $Fe_3O_4$ layer of the specimen, retarding further progression of corrosion.

• Applied Microscopy
• /
• v.45 no.3
• /
• pp.170-176
• /
• 2015

In this work, various electron microscopy and analysis techniques were used to investigate the microstructural evolution of a 9% Cr tempered martensite ferritic (TMF) steel T91 upon ultrasonic nanocrystalline surface modification (UNSM) treatment. The micro-dimpled surface was analyzed by scanning electron microscopy. The characteristics of plastic deformation and gradient microstructure of the UNSM treated specimens were clearly revealed by crystal orientation mapping of electron backscatter diffraction (EBSD), with flexible use of the inverse pole figure, image quality, and grain boundary misorientation images. Transmission electron microscope (TEM) observation of the specimens at different depths showed the formation of dislocations, dense dislocation walls, subgrains, and grains in the lower, middle, upper, and top layers of the treated specimens. Refinement of the $M_{23}C_6$ precipitates was also observed, the size and the number density of which were found to decrease as depth from the top surface decreased. The complex microstructure and microstructural evolution of the TMF steel samples upon the UNSM treatment were well-characterized by combined use of EBSD and TEM techniques.

• Applied Microscopy
• /
• v.48 no.2
• /
• pp.49-53
• /
• 2018

A successful transmission electron microscope (TEM) analysis is closely related to the preparation of the TEM specimen and should be followed by the suitable TEM specimen preparation depending on the purpose of analysis and the subject materials. In the case of the Si-based anode material, lithium atoms of formed Li silicide were removed due to ion beam and electron beam during TEM specimen preparation and TEM observation. To overcome the problem, we proposed a new technique to make a TEM specimen without the ion beam damage. In this study, two types of test specimens from the Si-based anode material of Li-ion battery were prepared by respectively adopting the only focused ion beam (FIB) method and the new FIB-ultramicrotome method. TEM analyses of two samples were conducted to compare the Ga ion damage of the test specimen.

• Journal of Korean society of Dental Hygiene
• /
• v.7 no.2
• /
• pp.105-113
• /
• 2007

It is necessary that current oral health education should be not only focused on grade schoolers, but provided for even junior and senior high schools on regular basis in favor of higher level of knowledge about dental health and the habituation of oral health promotion behaviors. So this study took total 288 respondents as sample from Grade 3 of 'C' high school(Suncheon city, Jeonnam) to examine their experiences in oral health education, their awareness of needs for oral health education and their demands for oral health education in the interest of providing basic materials for effective oral health education. 1. As the result of researching health awareness, 13.9% respondents answered that they didn't have good total body health, while 33.3% respondents felt that they didn't have good oral health. That is, more respondents felt that their oral health is not good, rather than total body health is. 2. For daily toothbrushing frequency, it was found that most respondents(62.6%) brushed their teeth 3 times a day, And for toothbrushing methods, it was found that 35.5% used manual toothbrushing(up-and-down toothbrushing movement) and 30.0% used semi-automatic toothbrushing(rotational movement). On the other hand, majority(89.4%) of respondents conducted tongue brushing, but only 10.8% benefited from dental examination on regular basis. 3. 28.1% respondents had experiences in oral health education. Out of them, 69.3% felt moderate satisfaction at the education. Majority(91.2%) of respondents were instructed once in oral health education, and 82.7% respondents were instructed in the oral health via practices(toothbrushing guidance). 77.8% respondents were instructed in the oral health at dental clinics. 4. As the result of surveying demands related to oral health education, 92.3% respondents answered that they need regular oral health education, and 82.9% respondents answered that they need oral health technicians in school. And 87.8% respondents needed individual oral health education for the benefit of better oral health.

• Applied Microscopy
• /
• v.46 no.1
• /
• pp.37-44
• /
• 2016

In this study $TiO_2$/reduced graphene oxide ($TiO_2/rGO$) bipyramid with tunable nanostructure was fabricated by two-step solvothermal process and subsequent heat-treatment in air. The as-synthesized anatase $TiO_2$ nanocrystals possessed morphological bipyramid with exposed dominantly by (101) facets. Polyethylenimine was utilized during the combination of $TiO_2$ and graphene oxide (GO) to tune the surface charge, hindering the restack of graphene during solvothermal process and resulting in 1 to 5 layers of rGO wrapped on $TiO_2$ surface. After a further calcination, a portion of carbon quantum dots (CQDs) with a diameter about 2 nm were produced owing to the oxidizing and cutting of rGO on $TiO_2$. The as-prepared $TiO_2/rGO$ hybrid showed a highly photocatalytic activity, which is about 3.2 and 7.7 times enhancement for photodegradation of methyl orange with compared to pure $TiO_2$ and P25, respectively. We assume that the improvement of photocatalysis is attributed to the chemical bonding between rGO/CQDs and $TiO_2$ that accelerates photogenerated electron-hole pair separation, as well as enhances light harvest.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.1 no.1
• /
• pp.51-61
• /
• 1995

This paper is discussed on the prospects of packaging industry and technologies of Japan for comming 21th century. It is clear that packaging industry depends on living style and social mechanizms. A trends of numerical consumption, amounts of money and composisition of packaging materials are one of a measure of development of packaging industry. Total consumption of packaging materials in Japan of 1965, 1980 and 1993 were $6,344.5{\times}10^3,\;15,898.7{\times}10^3\;and\;21,603.3{\times}10^3$ tons respectively and also, shipping money of packaging materials were $7,073{\times}10^{11},\;45,421{\times}10^{11}\;and\;63,902{\times}10^{11}$ yen, respectively. It is estimated from these data that the packaging industry is also increasing in future according of GNP of country. Compositions of packaging materials from 1965 to 1993, however, are somewhat changing according to development of new materials or social conditions such as platics packaging or wooden packaging materials. Technical forcasts of packaging industry are shown from view point of national living style, energy and resorces as well as environment of world based on forcasting committee of pulp & paper in Japan, report of research committee for the 21th packaging in JPI and materials of symposium in Kanagawa University in this paper. As a my conclusion, many functional packaging materials shall be developed in the future and accordingly Life Cycle Assesment plays a important role of packaging fields. Furthermore, I am estimating in future the new cellulosic materials such as nonwood fiber resources instead of paper, board, wooden containers and a part of plastic packaging materials shall be developed. This paper is constructed by three items as follow:

• Journal of Powder Materials
• /
• v.25 no.6
• /
• pp.475-481
• /
• 2018

Selective laser melting (SLM), a type of additive manufacturing (AM) technology, leads a global manufacturing trend by enabling the design of geometrically complex products with topology optimization for optimized performance. Using this method, three-dimensional (3D) computer-aided design (CAD) data components can be built up directly in a layer-by-layer fashion using a high-energy laser beam for the selective melting and rapid solidification of thin layers of metallic powders. Although there are considerable expectations that this novel process will overcome many traditional manufacturing process limits, some issues still exist in applying the SLM process to diverse metallic materials, particularly regarding the formation of porosity. This is a major processing-induced phenomenon, and frequently observed in almost all SLM-processed metallic components. In this study, we investigate the mechanical anisotropy of SLM-produced 316L stainless steel based on microstructural factors and highly-oriented porosity. Tensile tests are performed to investigate the microstructure and porosity effects on mechanical anisotropy in terms of both strength and ductility.

• Applied Microscopy
• /
• v.45 no.2
• /
• pp.37-43
• /
• 2015

In present work, work-hardening behavior of TiCu-based bulk metallic glass composite with B2 particles has been studied by systemic structural and mechanical investigations. After yield, pronounced work-hardening of the alloy was clearly exhibited, which was mainly related to the martensitic transformation as well as the deformation twinning in B2 particles during deformation. At the early plastic deformation stage (work-hardening stage), the stress-induced martensitic transformation from B2 phase to B19' phase and deformation-induced twinning of B19' phase was preferentially occurred in the around interface areas between B2 phase and amorphous matrix by stress concentration. The higher hardness value was observed in vicinity of interface within the B2 particles which are probably connected with martensitic transformation and deformation twinning. This reveals that the work-hardening phenomenon of this bulk metallic glass composite is a result of the hardening of B2 particles embedded in amorphous matrix.

• Journal of the Korean Society of Earth Science Education
• /
• v.8 no.1
• /
• pp.66-75
• /
• 2015

This study is to investigate an argumentation level for elementary school students after analysing an argumentation structure about a socio scientific issue(SSI), and inquire a change of the decision-making according to the refutation materials and empathic situation. This data was collected from the semi-structured interview with the 14 students, grade 6th. For this, the first stage is to present the reading materials about the SSI to the students, let them decision-making and make them argue pro and con about the SSI during the interview. After that, facing with the refutation materials against the existing contention and the empathic situation, the change of the decision-making of the students was conducted. After the research, the level of the argumentation of the students was low, and the students who didn't have the background knowledge about the theme made the decisions according to the values, emotions or intuitions of their own. And the decision-making of the students changed more when presented with the refutation materials and the empathic situation, they were difficult to make the decision because of new information and various stances. Besides, they lacked in the ability that recognize the situation related with their own life, just used the fragmentary knowledge associated with value of life respect. Through these result, it is necessary to produce the refutation materials and empathic materials about the SSI to the students for improving the level of argumentation.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.8
• /
• pp.1495-1498
• /
• 2008

$TiO_2$ nanopowders were synthesized by new sol-gel combustion hybrid method using acetylene black as a fuel. The dried gels exhibited autocatalytic combustion behaviour. $TiO_2$ nanopowders with an anatase structure and a narrow size distribution were obtained at 400-600 ${^{\circ}C}$. Their crystal structures were examined by powder Xray diffraction (XRD) and their morphology and crystal size were investigated by scanning electron microscopy (SEM). The crystal size of the nanopowders was found to be in the range of 15-20 nm. $TiO_2$ powders synthesized at 500 ${^{\circ}C}$ and 600 ${^{\circ}C}$ were applied to a dye solar cell. An efficiency of 5.2% for the conversion of solar energy to electricity ($J_{sc}$ = 11.79 mA/$cm^2$, $V_{oc}$ = 0.73 V, and FF = 0.58) was obtained for an AM 1.5 irradiation (100 mW/$cm^2$) using the $TiO_2$ nanopowder synthesized by the sol-gel combustion hybrid method at 500 ${^{\circ}C}$.