• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.715-731
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• 2021

Uncertainties are calculated for pressurized water reactor (PWR) spent nuclear fuel (SNF) characteristics. The deterministic code STREAM is currently being used as an SNF analysis tool to obtain isotopic inventory, radioactivity, decay heat, neutron and gamma source strengths. The SNF analysis capability of STREAM was recently validated. However, the uncertainty analysis is yet to be conducted. To estimate the uncertainty due to nuclear data, STREAM is used to perturb nuclear cross section (XS) and resonance integral (RI) libraries produced by NJOY99. The perturbation of XS and RI involves the stochastic sampling of ENDF/B-VII.1 covariance data. To estimate the uncertainty due to modeling parameters (fuel design and irradiation history), surrogate models are built based on polynomial chaos expansion (PCE) and variance-based sensitivity indices (i.e., Sobol' indices) are employed to perform global sensitivity analysis (GSA). The calculation results indicate that uncertainty of SNF due to modeling parameters are also very important and as a result can contribute significantly to the difference of uncertainties due to nuclear data and modeling parameters. In addition, the surrogate model offers a computationally efficient approach with significantly reduced computation time, to accurately evaluate uncertainties of SNF integral characteristics.

• Journal of Science Education
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• v.43 no.3
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• pp.363-381
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• 2019

This study aims to suggest an inclusive conceptual framework for the Nature of Technology (NOT) by examining literature and researches regarding NOT and then to analyze the conceptions of the students in Science and Engineering Department of a college based on the NOT framework. Findings are as follows: First, the conceptual framework of the NOT developed from the study has the five domains of NOT, which are Technology as Artifacts, Technology as Knowledge, Technology as Practice, Technology as History, and Technology as a part of Society. Second, the participants' conceptions of the NOT emphasize on three domains of the Technology as Practice (26.4%), Technology as a part of Society (25.8%), and Technology as Knowledge (24.3%) among the five domains of the NOT. Third, according to the microanalysis of the students' conceptions regarding NOT, students in Science and Engineering Department of a college possess concrete and various views of the NOT even though NOT is abstract and complex ideas. Specifically, they seem to recognize the NOT as a product of process and ability to utilize the technology for convenience of life.

• Advances in concrete construction
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• v.7 no.3
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• pp.183-189
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• 2019

In this study, it has been tried to prepare an analytical fragility curves for isolated straight continues highway bridges by considering different spectral intensity measures. A three-span concrete isolated bridge has been selected and the seismic performance of the bridge has been improved by Lead Rubber Bearing (LRB). Incremental Dynamic Analysis (IDA) is applied to the bridge in longitudinal direction. A suite of 14 earthquake ground motions from medium to sever motions are scaled and used for nonlinear time history analysis. Fragility function considers the relationship of earthquake intensity measures (IM) and probability of exceeding certain Damage State (DS). A full three dimensional finite element model of the isolated bridge has been developed and analyzed. A wide range of different intensity measures are selected and the optimal intensity measure which has the less dispersion is proposed.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.1
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• pp.63-68
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• 2003

We investigated the sequence divergence of the geographic samples of the queen bumble bee (Bombus ardens) in Korea. A portion of mitochondrial COI gene sequences (423 bp) was analyzed for 44 individuals collected from seven localities. Sequence analysis resulted in four COI haplotypes with the maximum nucleotide divergence of only 0.5% (two bp). One haplotype (BA1) was dominant in all localities surveyed (86.4%). The finding of low sequence divergence and dominance of one haplotype appear to reflect, although limited, the life history of the B. ardens queens subjected to active dispersal and seasonal fluctuation in queen number.

• Corrosion Science and Technology
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• v.2 no.2
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• pp.75-81
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• 2003

Chromium, molybdenum. and nitrogen are very important alloying elements in stainless steels and its effect was approved in pitting resistance equivalent (PRE) equations and many experimental results. However, Cr can improve the corrosion resistance, but facilitate the formation of sigma phase. Also. Mo has the same effect in stainless steels. If Cr and Mo are added at high amount to increase the corrosion resistance of stainless steel, corrosion resistance in annealed alloys can be improved, but in case of welding or aging heat treatment. its resistance will be drastically decreased. In this work, increasing Cr and N contents but decreasing Mo than the commercial alloys made the experimental alloys. Typical alloys are 25Cr-4.5Mo-0.43N alloy, 27Cr-4.7Mo-0.4N alloy, 27Cr-5.3Mo-0.25N alloy, 32Cr-2.6Mo-0.36N alloy. After annealing and aging heat treatment, microstructures, anodic polarization test, and pitting corrosion test were performed. Annealed alloys showed $100^{\circ}C$ of CPT and aged alloys showed the different tendency depending upon Cr and Mo contents(SFI)

• Ceramist
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• v.23 no.1
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• pp.4-15
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• 2020

The recent advances and popularity of 3D printing technology have centered around building polymerbased 'plastic' materials, due to their low cost, simple and efficient processing, and mechanical toughness. For this reason, printable polymers are actively recruited to create 'ceramic resins' that allow more facile fabrication of ceramic materials that are difficult to print directly. Herein, a brief history and the current state of ceramic 3D printing technology aided by polymer is summarized. In addition, a new ceramic 3D printing technology using polymer-derived ceramics (PDC) is also introduced.

• International Journal of Advanced Culture Technology
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• v.6 no.2
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• pp.80-85
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• 2018

In the 1990s, South Korea recently launched Space Development and is pushing for a step toward Space. In the Space Launch Vehicle field, the development of Practical satellite type Launch Vehicle (Korea Space Launch Vehicle II) has progressed to the stage of proprietary development, and in the field of Satellite development, they also have a great deal of competitiveness. This study will be a shortcut to rediscovering our potential and looking for breakthroughs by reviewing and re-examining the effects of past Space development.

• Structural Engineering and Mechanics
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• v.42 no.3
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• pp.363-381
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• 2012

This study is aimed at providing an efficient analytical model to obtain pressure- impulse diagram of one-way reinforced concrete slabs subjected to different shapes of air blast loading using single degree of freedom method (SDOF). A tri-linear elastic perfectly plastic SDOF model has been used to obtain the pressure-impulse diagram to correlate the blast pressure and the corresponding concrete flexural damage. In order to capture the response history for the slab, a new approximately SDOF method based on the conventional SDOF method is proposed and validated using published test data. The influences of pulse loading shape on the pressure-impulse diagram are studied. Based on the results, a pressure-impulse diagram generation method using SDOF and an analytical equation for the pressure-impulse diagram is proposed to different damage levels and different blast loading shapes.

• Journal of the Korea Furniture Society
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• v.17 no.4
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• pp.15-26
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• 2006

This article is composed of three parts in this article. The first part reviews, in the general, condition on Chinese forest resource history and analyzes the change in different historical times. The present condition and existing problems are discussed in the second part, where analyzes the existing problems in different distribution areas. In the third part, the solutions are raised to solve the problems mentioned in the second part. Finally the objective and strategy for sustainable development of Chinese forest resources are put forward.

• STI Policy Review
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• v.5 no.1
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• pp.131-144
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• 2014

The entrepreneurial university concept is a new challenge and opportunity for science and technology universities in Korea. The traditional university functions of education, research, and community service are still highly relevant, but increasingly so are new types of collaboration for research outcomes and funding resources. Strategic university management is needed to handle socioeconomic contribution, involving the creation and maintenance of proactive relationships with firms, national and regional governments, and other regional entities. The emergence of the entrepreneurial university in Korea is similar to the socioeconomic changes observable in the history of university development in America and in many other developed countries. In this paper, we examine the emerging paradigm of entrepreneurial universities in Korea and discuss the interactions among universities, firms, and government strategy and policy by investigating and comparing two universities, POSTECH and KAIST, in their leadership, adaptation to changes in the environment, business strategies, organization, and cooperative network. We conclude with policy points that emphasize the fact that while entrepreneurial universities are an emerging concept, they can expand innovation and creativity in education and research in Korean universities in the mid-to-long term if university administration, policymakers and public administrators, and regional innovation actors take an interest in the need for a new organization and system where university research can contribute socioeconomically.