• Geomechanics and Engineering
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• v.7 no.4
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• pp.375-401
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• 2014

It is generally accepted that material heterogeneity has a great influence on the deformation, strength, damage and failure modes of rock. This paper presents numerical simulation on rock failure process based on the characterization of rock heterogeneity by using a digital image processing (DIP) technique. The actual heterogeneity of rock at mesoscopic scale (characterized as minerals) is retrieved by using a vectorization transformation method based on the digital image of rock surface, and it is imported into a well-established numerical code Rock Failure Process Analysis (RFPA), in order to examine the effect of rock heterogeneity on the rock failure process. In this regard, the numerical model of rock could be built based on the actual characterization of the heterogeneity of rock at the meso-scale. Then, the images of granite are taken as an example to illustrate the implementation of DIP technique in simulating the rock failure process. Three numerical examples are presented to demonstrate the impact of actual rock heterogeneity due to spatial distribution of constituent mineral grains (e.g., feldspar, quartz and mica) on the macro-scale mechanical response, and the associated rock failure mechanism at the meso-scale level is clarified. The numerical results indicate that the shape and distribution of constituent mineral grains have a pronounced impact on stress distribution and concentration, which may further control the failure process of granite. The proposed method provides an efficient tool for studying the mechanical behaviors of heterogeneous rock and rock-like materials whose failure processes are strongly influenced by material heterogeneity.

• Journal of The Korean Association For Science Education
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• v.4 no.2
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• pp.57-63
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• 1984

An inquiry approach in teaching science has been advocated by many science educators for the past few decades, and most elementary and secondary science curricula have incorporated it in varying degrees. It has been proven in recent studies, however, that there exists considerable discrepancy between the expectation of outcomes of the inquiry approach and the actuality. This in part implies that there is a somewhat urgent need for the systematic evaluation of the approach in teaching science. The purpose of this study is to develop a comprehensive instrument for evaluating inquiry teaching approaches embedded in science curricular materials. To develop a more valid and reliable instrument a set of empirical data was used in the developmental procedure, and most of the previous studies regarding inquiry teaching method and inquiry evaluation were consulted. The inquiry evaluation method developed in this study, called the Scientific Inquiry Evaluation Inventory (SIEI), is composed of three parts: (1) analyzing and coding each science process task of inquiry activity; (2) evaluating each inquiry activity as a whole; and (3) evaluating each science laboratory curriculum as a whole. The first part of the instrument consists of twenty science process categories and thirty subcategories grouped into four sections: (1) gathering and organizing data; (2) interpreting and analyzing data; (3) synthesizing results and evaluation; and (4) hypothesizing and designing an experiment. The science process categories are arranged according to the level of difficulty, psychological level of thinking, degree of creativity demand, and the model of the process of scientific inquiry, which is also developed in the study. The second part of the instrument contains four evaluation scales of inquiry activity: (1) competition/cooperation scale; (2) discussion scale; (3) openness scale; and (4) inquiry scope scale. And the last part consists of three methods for evaluating a science laboratory curriculum as a whole: (1) inquiry pyramid; (2) inquiry index; and (3) difficulty index. The instrument is designed to be used by teachers, science curriculum developers and science education evaluators for the purpose of diagnosing the nature and appropriateness of scientific inquiry introduced in secondary science curricular materials, especailly in laboratory work and field work.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2682-2695
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• 2021

This paper aims to evaluate the structural dynamic responses and damage/failure of the nuclear fuel reprocessing plant under the free drop impact of spent fuel cask (SFC) and fuel assembly (FA) during the on-site transportation. At the present Part I of this paper, the large-scale SFC model free drop test and the corresponding numerical simulations are performed. Firstly, a composite target which is composed of the protective structure, i.e., a thin RC plate (representing the inverted U-shaped slab in the loading shaft) and/or an autoclaved aerated concrete (AAC) blocks sacrificial layer, as well as a thick RC plate (representing the bottom slab in the loading shaft) is designed and fabricated. Then, based on the large dropping tower, the free drop test of large-scale SFC model with the mass of 3 t is carried out from the height of 7 m-11 m. It indicates that the bottom slab in the loading shaft could not resist the free drop impact of SFC. The composite protective structure can effectively reduce the damage and vibrations of the bottom slab, and the inverted U-shaped slab could relieve the damage of the AAC blocks layer dramatically. Furthermore, based on the finite element (FE) program LS-DYNA, the corresponding refined numerical simulations are performed. By comparing the experimental and numerical damage and vibration accelerations of the composite structures, the present adopted numerical algorithms, constitutive models and parameters are validated, which will be applied in the further assessment of drop impact effects of full-scale SFC and FA on prototype nuclear fuel reprocessing plant in the next Part II of this paper.

• Journal of the Korean Society of Visualization
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• v.14 no.3
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• pp.3-10
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• 2016

• Proceedings of the Korean Vacuum Society Conference
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• 2001.02a
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• pp.26-27
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• 2001

• Applied Biological Chemistry
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• v.37 no.4
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• pp.303-309
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• 1994

To develop the treatment process of swine wastewater using Rhodopseudomonas palustris KK14 with high utilizable ability of organic acids, some operating conditions were investigated and optimized in flask-scale and laboratory-scale reactors. The optimal operating conditions in photosynthetic bacteria (PSB) reactor of semi-continuous type were obtained at HRT 6 day, 5% (v/v/day) seeding rate of PSB sludge and 10% (v/v/day) returning rate of PSB return sludge. Under the above operating condition, COD level of the wastewater (initial COD: 10 g/l) was reduced to about 1.7 g/l after 4 days treatment and MLSS was held constant at $4{\sim}5\;g$ per liter. In laboratory-scale process consisted of 5.2 l anaearobic digestion reactor and 15 l PSB reactor, the total removal rates of COD and BOD were increased to 95% and 96% by the continuous operation for 5.36 days, respectively, showing $3kg\;COD/m^3/day$ COD loading rate and 1.1 Kg COD/Kg MLSS/day sludge loading rate in PSB reactor. The offensive odor was considerably removed through the treatment process of swine wastewater.

• Structural Engineering and Mechanics
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• v.69 no.6
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• pp.637-649
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• 2019

In the current research paper, a quasi-3D beam theory is developed for free vibration analysis of functionally graded microbeams. The volume fractions of metal and ceramic are assumed to be distributed through a beam thickness by three functions, power function, symmetric power function and sigmoid law distribution. The modified coupled stress theory is used to incorporate size dependency of micobeam. The equation of motion is derived by using Hamilton's principle, however, Navier type solution method is used to obtain frequencies. Numerical results show the effects of the function distribution, power index and material scale parameter on fundamental frequencies of microbeams. This model provides designers with guidance to select the proper distributions and functions.

• Korean Journal of Clinical Laboratory Science
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• v.37 no.2
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• pp.111-117
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• 2005

The purpose of this study is to provide the basic guidelines of spatial and physical environment for the planning and design of clinical laboratory by analysing the extent of satisfaction of clinical laboratory scientists. The data for this analysis was gathered from March to May 2005 by the questionnaires of 208 clinical laboratory scientists who work in the 13 hospitals. All the collected data was analyzed by the SPSSWIN program. In this study, the satisfaction measurement tool was composed with 8 items and 5 score scale. The mean score of satisfaction for spatial and physical environment was 2.89 out of 5.0, "noise" was the lowest 2.40, "temperature and moisture of the lab." was 2.72, "lab. area, service area and administration area" was 2.77, "passageway space" was 2.94, circulation of workers was 2.94, "color of finish" was 3.19, "lighting of lab." was the highest 3.39. In conclusion, various factors, noise, temperature and moisture, clinical lab area, were evaluated to moderate dissatisfaction. Noise was especially the first serious problem in clinical lab. Considering the high growth of the number of tests, the planning of the clinical laboratory size should be considered not only to provide the optimal size but how it will correspond to the growth of the number of tests. Therefore the arrangement of each section need to be flexible in arrangement which is inevitable in expansion and reconstruction in the future.

• Journal of Microbiology and Biotechnology
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• v.26 no.7
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• pp.1320-1332
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• 2016

Light hydrocarbons accumulated in subsurface soil by long-term microseepage could favor the anomalous growth of indigenous hydrocarbon-oxidizing microorganisms, which could be crucial indicators of underlying petroleum reservoirs. Here, Illumina MiSeq sequencing of the 16S rRNA gene was conducted to determine the bacterial community structures in soil samples collected from three typical oil and gas fields at different locations in China. Incubation with n-butane at the laboratory scale was performed to confirm the presence of "universal microbes" in light-hydrocarbon microseepage ecosystems. The results indicated significantly higher bacterial diversity in next-to-well samples compared with background samples at two of the three sites, which were notably different to oil-contaminated environments. Variation partitioning analysis showed that the bacterial community structures above the oil and gas fields at the scale of the present study were shaped mainly by environmental parameters, and geographic location was able to explain only 7.05% of the variation independently. The linear discriminant analysis effect size method revealed that the oil and gas fields significantly favored the growth of Mycobacterium, Flavobacterium, and Pseudomonas, as well as other related bacteria. The relative abundance of Mycobacterium and Pseudomonas increased notably after n-butane cultivation, which highlighted their potential as biomarkers of underlying oil deposits. This work contributes to a broader perspective on the bacterial community structures shaped by long-term light-hydrocarbon microseepage and proposes relatively universal indicators, providing an additional resource for the improvement of microbial prospecting of oil and gas.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.71-79
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• 2023

Air ingress incidents are major safety accidents in very-high-temperature reactors (VHTRs). Air containing a high volume fraction of oxygen may cause severe oxidation of core components at the VHTR, especially for the significantly thin alloy tube wall in the intermediate heat exchanger (IHE). The research objects of this study are Inconel 617 and Incoloy 800H, two candidate alloys for IHE in VHTR. The air ingress accident scenario is simulated with high-temperature air flow at 950 ℃. A continuous oxide scale was formed on the surfaces of both the alloys after the experiment. Because the oxide scale of Inconel 617 has a loose structure, whereas that of Incoloy 800H is denser, Inconel 617 exhibited significantly more severe internal oxidation than Incoloy 800H. Further, Inconel 617 showed a significant decrease in ultimate tensile strength and plasticity after aging for 200 h, whereas Incoloy 800H maintained its tensile properties satisfactorily. Through control experiment under vacuum, we preliminarily concluded that serious internal oxidation is the primary reason for the decline in the tensile properties of Inconel 617.