• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.423-428
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• 2016

The last stage blades of a low pressure (LP) turbine get frequently fractured because of stress corrosion cracking. This is because they operate in a severe corrosive environment that is caused by the impurities dissolved in condensed steam and high stress due to high speed rotation. To improve the reliability of the blades under severe conditions, 12% Cr martensitic stainless steel, having excellent corrosion resistance and higher strength, is widely used as the blade material. This paper shows the result of root cause analysis on a blade which got fractured suddenly during normal operation. Testing of mechanical properties and microstructure examination were performed on the fractured blade and on a blade in sound condition. The results of testing of mechanical properties of the fractured blade showed that the hardness were higher but impact energy were lower, and were not meeting the criteria as per the material certificate specification. This result showed that the fractured blade became embrittled. The branch-type crack was found to have propagated through the grain boundary and components of chloride and sulfur were detected on the fractured surface. Based on these results, the root cause of fracture was confirmed to be stress corrosion cracking.

• Journal of Pharmacopuncture
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• v.19 no.4
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• pp.319-328
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• 2016

Objectives: Advancements in nanotechnology have led to nanoparticle (NP) use in various fields of medicine. Although the potential of NPs is promising, the lack of documented evidence on the toxicological effects of NPs is concerning. A few studies have documented that homeopathy uses NPs. Unfortunately, very few sound scientific studies have explored the toxic effects of homeopathic drugs. Citing this lack of high-quality scientific evidence, regulatory agencies have been reluctant to endorse homeopathic treatment as an alternative or adjunct treatment. This study aimed to enhance our insight into the impact of commercially-available homeopathic drugs, to study the presence of NPs in those drugs and any deleterious effects they might have, and to determine the distribution pattern of NPs in zebrafish embryos (Danio rerio). Methods: Homeopathic dilutions were studied using high-resolution transmission electron microscopy with selected area electron diffraction (SAED). For the toxicity assessment on Zebrafish, embryos were exposed to a test solution from 4 - 6 hours post-fertilization, and embryos/larvae were assessed up to 5 days post-fertilization (dpf ) for viability and morphology. Toxicity was recorded in terms of mortality, hatching delay, phenotypic defects and metal accumulation. Around 5 dpf was found to be the optimum developmental stage for evaluation. Results: The present study aimed to conclusively prove the presence of NPs in all high dilutions of homeopathic drugs. Embryonic zebrafish were exposed to three homeopathic drugs with two potencies (30CH, 200CH) during early embryogenesis. The resulting morphological and cellular responses were observed. Exposure to these potencies produced no visibly significant malformations, pericardial edema, and mortality and no necrotic and apoptotic cellular death. Conclusion: Our findings clearly demonstrate that no toxic effects were observed for these three homeopathic drugs at the potencies and exposure times used in this study. The embryonic zebrafish model is recommended as a well-established method for rapidly assessing the toxicity of homeopathic drugs.

• Archives of design research
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• v.15 no.4
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• pp.317-326
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• 2002

The Web has taken a strong post as one of the media for advertisement for long time. The Internet has an advantage of an easy access to each of customers; the fractioning of the potential customers; the transcending of the time and space; and the utilizing of the multimedia. As such, the Web as a communication tool has not only all characteristics of the existing media but also the factors such as the sound, motion, and interaction. Therefore the Web designing should be much more flexible and open than any other medias. Nevertheless, most of the Webs being created currently appear to be simply perfunctory and functional. This is because a methodological aspect has not been rooted firmly as the Web design industry has been developed too rapidly, driven by the explosive demand. Therefore, this study is designed to demonstrate the approaching method to the Web-interface designing as an alternative for such methodological aspect. In other words, it is the very stillness-motion interface designing of the Web, based on the e-advertisement concept. The Web as one of the media for advertisement gives the heaviest weight to the users emotional aspects than any other media do. Therefore, it is very important to get the differentiation and impact in the Web-interface designing through the users emotional aspects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.666-671
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• 2018

A honeycomb panel is a plate made by attaching two surface plateson eitherside of a honeycomb core. The honeycomb plate hasexcellent specific strength and energy absorption and is suitable for use in regions where good impact resistance is required. Recently, with the increasing the need for a lightweight design to facilitate transportation, numerous studies have been conducted using aluminum honeycomb plates as body materials for vehicles such as automobiles and high-speed trains. In addition, honeycomb plates have excellent sound deadening properties, as well as excellent heat insulation and durability. Savings in weight using lightweight materials such as aluminum alloy for honeycomb panel's skin can lead to increase fuel economy and reduction in air pollution. In this study, in order to improve the design technology of the honeycomb plate material, the manufacturing technology of the aluminum honeycomb core and honeycomb plate material and various mechanical properties of the honeycomb plate were evaluated. From the results, it was found that the design of the manufacturing process of the aluminum honeycomb plate, as well as itsproduction and characteristics, were improved. The resulting excellent energy absorption capability of the honeycomb plate was due to the repetitive core buckling, indicating that the higher the compressive strength, the higher the strength per bonded area.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.120-125
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• 2015

With rapid urbanization, the volume of traffic in urban area has been significantly increased. This in turn led to problem which can be described as Road Traffic Noise. Currently, to alleviate the road traffic noise damage, a demand for installation of soundproofing walls is rising. Among different shapes of soundproof walls being installed, the reflection-type acoustical insulation panel is highly drawing attentions of residents due to the fact that it does not obstruct their field of vision in contrast with the opaque acoustical insulation panel. On the other hand, improving the soundproofing wall of the reflection-type acoustical insulation barrier panel needs to be focused on since it has a possibility to cause a secondary damage by reflected sounds. Therefore, in this research, study has been carried out to improve the forms in order to minimize travelling of reflected sounds through changing the frontal surface shape and geometrical shape of the reflection-type soundproofing panel. A result from comparison between the normal reflection-type soundproofing panel and the improved soundproofing panel, with reduction effects in the noise reflection, showed that the curved type of soundproofing panel has an impact on reducing the noise up to 1.5 dB. Furthermore, from the research conducted, it appears that the increase and decrease in the reflected sounds can be changeable depending on various design factors. Thus, it turns out that the study shows a potential possibility to develop a reduction technology of the reflected sounds pertaining to overall condition on the soundproofing walls.

• Korean Journal of Environment and Ecology
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• v.24 no.3
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• pp.302-317
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• 2010

In this study, not only to present the management plan but also to verify the effectiveness for a area of improving the landscape and the area of creating the base of bio-inhabitation in Tancheon stream concrete embankment where were practised the vegetation-mat measures for greening via monitoring i.e. restoration progress. The results of monitoring, there were a total of 41 taxa, 18 families, 38 species, 3 varieties in 2006, moreover in the 2007, there were a total of 59 taxa, 19 families, 56 species, 3 varieties and in the period 2008, 64 taxa, 29 families, 59 species, 8 varieties. Therefore, these site has increased the plant spaces year by year. The distribution of vegetation characteristics shows that Miscanthus sacchariflorus and Pennisetum alopecuroides expands their influence in the area of applying the construction method. Those area appears a diversity of native species by the stream deposition at the flood. Thus, its condition is very soundly ecological health and eco-friend. At present, native species have been dominant, however, disturbed species and invasive species can be expected to increase dramatically in the future. Therefore, it is necessary to a long-range monitoring and management for maintaining an environmentally sound aquatic ecosystem. On this area refer to mix the river vegetation of primary succession and disturbed vegetation. For that reason, the method of constructing the vegetation-mat measures for greening in embankment does not need to remove the concrete and can install a coir-mat on the top. It leads to improve the landscape, moreover, it was analysed the such dramatic changes in the vegetation species richness by providing continuous the plant growth basis have a impact on in bio-diversity.

• Korean Journal of Environment and Ecology
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• v.26 no.2
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• pp.233-246
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• 2012

We need to analyze the ecological characteristics in the basin of agricultural reservoir that include urbanized area, agricultural area and fringe area, etc. The purpose of this study is not only that presenting the methods of basin ecosystem management but also suggesting ecosystem management plan proposals for the water quality based on analysis of ecological characteristics. As the results of analysis, the urbanized area(the ratio of area(ROA): 14.0%) is most likely to possibility of water pollution, then followed by paddy fields(ROA: 65.5%) where a wide spread up-basin(or up-stream), farmlands(ROA: 11.3%), farm buildings(ROA: 5.7%) and orchard(ROA: 3.9%). According to those, we investigated the impact degree of water pollutants. Thus, we were able to classify 5 types through considering the biotope assessment and the hydrosphere basin assessment, i.e. the level of priority control for source pollution. As a result, the source pollution intensive management area(11.3%) where are adjacent waterfront has caused water pollution, however, most importantly, it is necessary to control in source pollution management area(0.6%) that are away from waterfront. In conclusion, according to the these results, the plan of basin ecosystem management for the water quality should be included the plan of ecosystem conservation and restoration such as improving inhabitants function, controling environmentally sound basin management, promoting biodiversity.

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.235-242
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• 2010

Emotion science is one of the rapidly expanding engineering/scientific disciplines which has a major impact on human society. Such growing interests in emotion science and engineering owe the recent trend that various academic fields are being merged. In this paper we review the recent techniques in the measuring the emotion related elements and applications which include animal model system to investigate the neural network and behaviour, artificial nose/neuronal chip for in-depth understanding of sensing the outer stimuli, metabolic controlling using emotional stimulant such as sounds. In particular, microfabrication techniques made it possible to construct nano/micron scale sensing parts/chips to accommodate the olfactory cells and neuron cells and gave us a new opportunities to investigate the emotion precisely. Recent developments in the measurement techniques will be able to help combine the social sciences and natural sciences, and consequently expand the scope of studies.

• Journal of The Korean Association For Science Education
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• v.26 no.2
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• pp.239-245
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• 2006

The purposes of this study were to develop and implement a teaching strategy that reinforced teacher-student interaction for middle school first grade science and investigate the impact of the teaching strategy on student comprehension of scientific concepts, logical thinking ability, and science-related attitudes. 200 students attending a co-ed middle school located in Gyeonggi province were selected for the study and divided into an experiment and control group each consisting of 100 pupils. The teaching strategy reinforcing teacher-student interaction was applied to the experiment group, while conventional teaching, teacher-led lecturing, was carried out on the control group. To accomplish reinforced teacher-student interaction teacher asked students diversified questions and gave delayed feedbacks that deliberately focused on thought provocation. Results showed that the developed teaching strategy was effective in improving the students' logical thinking ability(p<.01). However, no significant differences were found in student comprehension of scientific concepts and science-related attitudes between the experimental and control group(p<.05). It was determined that more sound research is needed to develop and apply a lesson plan based on the teaching strategy used in this study.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.93-99
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• 2000

Treatment of shaving scrap, a chrome containing solid scrap generated by leather manufacturing process, has been so far depended on mainly incineration, soil landfill and ocean dumping, which give bad impact on environment and cause pollution. Shaving scrap generates from the mechanical work for controlling the final thickness of leather and its main components are collagen protein and pan of chromium compound. For the purpose of reusing this leather waste as resources, researches in connection with collagen fiber recovery, gelable protein recovery and liquid fertilizer is being speedily progressed. In the experiment, shaving scrap went through wet pulverizing treatment by physical and chemical methods. Then, making the leather sheet evenly, it is mixed with natural latex and every kind of binding materials in the container, and the mixtures were passed through experimental hydraulic press machine and applied to Fourdrinier machine respectively. Lastly, a test for fading out physical strength and properties of multiple-purpose of leather-like material was performed on a continuous leather sheet prepared by the experiment. In result, the physical strength and properties of leather-like material showed noticeable differences according to mixing ratio of binding materials, beating methods and the Ends of binding materials selected, and generally tear strength was the weakest property among others. Also, by the pilot scale experiment in sequence, it was possible to manufacture recycled goods made of soft and hard types of leather-like material with various performances.