• International Journal of Concrete Structures and Materials
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• v.10 no.1
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• pp.47-60
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• 2016

The objective of this study was to evaluate the capability of different strength-maturity models to account for the effect of the hydration heat on the in-place strength development of high-strength concrete specifically developed for nuclear facility structures under various ambient curing temperatures. To simulate the primary containment-vessel of a nuclear reactor, three 1200-mm-thick wall specimens were prepared and stored under isothermal conditions of approximately $5^{\circ}C$ (cold temperature), $20^{\circ}C$ (reference temperature), and $35^{\circ}C$ (hot temperature). The in situ compressive strengths of the mock-up walls were measured using cores drilled from the walls and compared with strengths estimated from various strength-maturity models considering the internal temperature rise owing to the hydration heat. The test results showed the initial apparent activation energies at the hardening phase were approximately 2 times higher than the apparent activation energies until the final setting. The differences between core strengths and field-cured cylinder strengths became more notable at early ages and with the decrease in the ambient curing temperature. The strength-maturity model proposed by Yang provides better reliability in estimating in situ strength of concrete than that of Kim et al. and Pinto and Schindler.

• The Journal of Industrial Distribution & Business
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• v.9 no.5
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• pp.83-91
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• 2018

Purpose - The purpose of this study is to explore the introduction and activation of smart training for the effective training of vocational ability development of companies in the 4th industrial revolution era, we analyze the present status of smart training introduction and related difficulties and propose concrete activation plan. Research design, data, and methodology - Through the online survey, we tried to confirm the recognition of corporate about smart training. Questionnaires include what are the benefits, expectations, and difficulties of smart training, etc. The survey was conducted from August 21, 2017 to September 4, 2017. A total of 69 companies participated in the questionnaire. The questionnaire results were analyzed through frequency analysis and contents analysis. Based on the results of the questionnaire, we found out the cause of inhibition of smart training activation and suggested activation strategies. Results - The main reason for the provision of smart training is the expectation of the training performance and the recognition that it is possible to provide training in a flexible manner. The effectiveness of smart training operation was evaluated as a high level of contribution to the development of creative training course and the capacity of training institute. As a result of checking factors that hinders the activation of smart training, the most important reason is that the time and cost burden of the training institutes is excessive. The lack of expertise in the design of smart training courses and the burden of employers and trainees. Conclusions - In order to activate smart training, it is necessary to find solutions to the obstacles at the internal or external level of training institutions. The internal barriers to the training organization are lack of internal competence for preparation and course management. In this regard, we need to consider providing consulting, best practices or guidance in the process of designing and operating smart training. On the other hand, as an external obstacle factor, it is necessary to provide incentives to participate in smart training. In addition, further research is needed on strategies that can lead to participation in smart training from the viewpoint of employers and learners.

• Journal of radiological science and technology
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• v.47 no.3
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• pp.183-195
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• 2024

Additional functional upgrades to the large-area compton camera (LACC) measurement device that can provide characteristics evaluation information (nuclear species and radioactivity) and two-dimensional or three-dimensional distribution imaging information of radioactive materials existing in surface or internal of concrete structures are required in terms of work stability and efficiency in order to apply to actual decommissioning sites such as nuclear power plants or medical cyclotron facilities by using this measurement device. To this purpose, the technology that allows radiation workers to intuitively and visually check the distribution of radioactive materials in advance by matching the two-dimensional distribution imaging information of radioactive materials obtained through the LACC measurement device and visual imaging of the measurement zone (10 m × 5 m) was developed. In addition, the separate system that can automatically adjust the position (height) in units of the measurement area size (0.7 m × 0.3 m × 0.8 m) of the LACC measurement device was developed and the integrated management system for characteristics evaluation information and two-dimensional or three-dimensional distribution imaging information obtained per unit of measurement for radioactive materials was developed. These functional upgrades related to LACC measurement device can improve work efficiency and safety when measuring radioactivity of concrete structures and enable the establishment of appropriate decommissioning strategies using radioactivity measurement information for decommissioning nuclear power plants or medical cyclotron facilities.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.903-906
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• 2008

To analyze the growth of SOB (Thiobacillus novellus) and biochemical corrosion of concrete, simulation test method and device were developed. And two types of simulation tests were conducted according to a transplant method and a concentration of H2SO4. As a result, the SOB growth in distinct manners and antibiosis of specimen were observed. In the case of the specimens indirectly transplanted with SOB through culture solution submersion at a hydrogen sulfide level of 120ppm, the rapid activation of SOB and the resulting sulfuric acid production were observed. However, SOB were shown to grow rapidly and then die out in a relative short period of time. Meanwhile, in the case of the specimens directly transplanted with SOB at a hydrogen sulfide level of 50ppm, the long-term growth of SOB was possible, but the production of sulfuric acid by SOB did not progress. In the case of the antibiotic metal-mixed specimens, SOB with destroyed cell membranes and internal organizations were observed.

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.495-502
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• 2008

To analyze the growth of SOB(Thiobacillus novellus) and biochemical corrosion of concrete, simulation test method and device were developed, and basic conditions for SOB growth were established. Two types of simulation tests were conducted according to a transplant method and a concentration of $H_2SO_4$. As a result, the SOB growth in distinct manners and antibiosis of specimen were observed. In the case of the specimens indirectly transplanted with SOB through culture solution submersion at a hydrogen sulfide level of 120 ppm, the rapid activation of SOB and the resulting sulfuric acid production were observed. However, SOB were shown to grow rapidly and then die out in a relative short period of time. Meanwhile, in the case of the specimens directly transplanted with SOB at a hydrogen sulfide level of 50 ppm, the long-term growth of SOB was possible, but the production of sulfuric acid by SOB did not progress. In the case of the antibiotic metal-mixed specimens, SOB with destroyed cell membranes and internal organizations were observed.