• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.20 no.4
• /
• pp.429-453
• /
• 2022

Numerical modeling and scenario composition are needed to characterize the geological environment of the disposal site and analyze the long-term evolution of natural barriers. In this study, processes and features of the hydro-mechanical behavior of natural barriers were categorized and represented using the interrelation matrix proposed by SKB and Posiva. A hydro-mechanical coupled model was evaluated for analyzing stress field changes and fracture zone re-activation. The processes corresponding to long-term evolution and the hydro-mechanical mechanisms that may accompany critical processes were identified. Consequently, practical numerical methods could be considered for these geological engineering issues. A case study using a numerical method for the stability analysis of an underground disposal system was performed. Critical stress distribution regime problems were analyzed numerically by considering the strata's movement. Another case focused on the equivalent continuum domain composition under the upscaling process in fractured rocks. Numerical methods and case studies were reviewed, confirming that an appropriate and optimized modeling technique is essential for studying the stress state and geological history of the Korean Peninsula. Considering the environments of potential disposal sites in Korea, selecting the optimal application method that effectively simulates fractured rocks should be prioritized.

• Nuclear Engineering and Technology
• /
• v.45 no.1
• /
• pp.41-52
• /
• 2013

Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high-level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

• Journal of the Korean Society for Library and Information Science
• /
• v.46 no.2
• /
• pp.199-217
• /
• 2012

This study analyzes the correlation between the library anxiety and personality traits. The library anxiety (LAS) and personality traits (the Korean BFI) were measured against 49 freshmen in the university. The library anxiety was average 2.57, 'mechanical barriers' score was the highest(2.91), subsequently was 'affective barriers' 2.72, 'barriers with staff' 2.49, 'knowledge of library' 2.42, and 'comfort with the library' score was the lowest(2.38). The personality traits had the tendency that 'agreeableness'f actor(3.65) is higher than other 4 factors, 'neuroticism'(3.48), 'extraversion'(3.27), 'openness'(2.85), and 'conscientiousness' (3.26). It found that 'comfort with the library' and 'neuroticism' were correlated statistically and the personality traits have an effect on library anxiety. Based on the findings, the following recommendations are made: improving the measurement tool of information anxiety, using other personality traits variables in similar researches, and developing personalized library anxiety resolution programs.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.4
• /
• pp.275-281
• /
• 2014

This study has been analyzed the sound performance of the noise barriers with respect to the configuration of the front perforated panel geometries and the filled absorption materials. Noise barriers' acoustic performance should be required to meet 0.7 of NRC value at least. The global absorbing performance of the barriers have been investigated by changing the opening ratio of the front perforated panel and the absorbing characteristics of the absorbing material using two microphone method. Therefore, It it possible to obtain to increase acoustic performance of the specific frequency ranges by designing the perforate rates of the front panel and absorbing characteristics of the absorbing materials inside, as well. This study try to find out the possibilities of applying the absorbing noise barrier to railway usage.

• Geomechanics and Engineering
• /
• v.2 no.3
• /
• pp.213-227
• /
• 2010

Compacted layers of sand-bentonite mixtures have been proposed and used in a variety of geotechnical projects as engineered barriers for the enhancement of impervious landfill liners, cores of zoned earth dams and radioactive waste repository systems. This paper presents a study on the valorization of local materiel such as dune sand from Laghouat region and mine bentonite intended for the realization of liner base layers in the conception of insulation barriers for hazardous waste centers. In the practice we try to get an economical mixture that satisfies the hydraulic and mechanical properties specified by regulation rules. The effect of the bentonite additions on the mixture is reflected by its capability of clogging the matrix pores upon swelling. In order to get an adequate dune sand-bentonite mixture, an investigation on hydraulic and mechanical behaviours is carried out in this study for different mixtures. Using oedometer test, the adequate bentonite addition to the mixture, which satisfies the conditions on permeability, is found to be around 12% to 15%. These results are also confirmed by direct measurement using triaxial cell.

• Tunnel and Underground Space
• /
• v.33 no.1
• /
• pp.42-56
• /
• 2023

In deep geological disposal of high-level radioactive waste (HLW), the natural barrier must physically support the disposal facility and delay the movement of radionuclides for at least hundreds of thousands of years. To evaluate the long-term geological evolution of the natural barriers, it is essential to analyze the long-term behavior of rock joints, including the frictional healing behavior. This study aimed to experimentally analyze the frictional healing behavior of rock joints under hydro-mechanical (H-M) conditions through the slide-hold-slide (SHS) test. The SHS tests were performed under mechanical and H-M conditions for joint specimens of different roughness. In the H-M conditions, the frictional healing rate tended to increase, which was more evident in the specimens with large roughness. In addition, it was confirmed that the effect of the hydro-mechanical conditions was more significant when the effective normal stress acting on the joint surface was small. These results are expected to be used as fundamental data to understand the frictional healing behavior of rock joints in the natural barriers.

• Nuclear Engineering and Technology
• /
• v.51 no.4
• /
• pp.1047-1059
• /
• 2019

This work describes the development of a numerical module with a multiphysics structure to simulate the thermo-hydro-chemo-mechanical behavior of compacted bentonites. First, the conceptual model, based on the state-of-the-art formulation for clay-based engineered barriers in deep geological repositories, is described. Second, the advantages of multiphysics-based modules are highlighted. Then, the guidelines to develop a code using such tools are outlined, presenting an example of implementation. Finally, the simulation of three tests that illustrate the behavior of compacted bentonites assesses the scope of the developed code. The satisfactory results obtained, and the relative simplicity of implementation, show the opportunity of the modeling strategy proposed.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.2
• /
• pp.137-164
• /
• 2018

The guarantee of the performance of the engineered barriers in a geological repository is very important for the long-term safety of disposal as well as the efficient design of the repository. Therefore, the performance of the engineered barriers under repository condition should be demonstrated by in-situ experiments conducted in an underground research laboratory. This article provides a review of the major in-situ experiments that have been carried out over the past several decades at underground research laboratories around the world to validate the performance of engineered barriers of a repository, as well as their results. In-situ experiments to study the coupled thermal-hydraulic-mechanical behavior of the engineered barrier system used to simulate the post-closure performance of the repository are analyzed as a priority. In addition, in-situ experiments to investigate the performance of the buffer material under a real repository environment have been reviewed. State-of-the art in-situ validations of the buffer-concrete interaction, and the installation of the buffer, backfill and plug, as well as characterization of the near-field rock and the corrosion of the canister materials are, also performed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.2
• /
• pp.131-134
• /
• 2011

We propose a spheroid chip that uses removable cell trapping barriers and that is capable of forming and extracting multicellular spheroids. By using a conventional well plate and flask, it is difficult to form small-sized spheroids, which resemble avascular 3D cell-cell interaction. It was difficult to extract spheroids using conventional microchips and fixed cell trapping barriers. The proposed chip, however, facilitates both formation and extraction of spheroids by using removable cell trapping barriers formed by membrane deflection. The cell trapping barriers, formed at the membrane pressure of 50 kPa, hold the cells in the trapping region at a cell inlet pressure of 145.155 Pa. After incubation for 24 h, the trapped cells form uniform spheroids. We successfully extract the spheroids at a cell inlet pressure of 5 kPa after removing the membrane pressure. The extracted spheroids have a diameter of $197.2{\pm}11.7Bm$ with a viability of $80.3{\pm}7.7%$. Using the proposed chip, uniform spheroids can be formed and these spheroids can be safely extracted for carrying out the post-processing of spheroids.

• KIEAE Journal
• /
• v.9 no.1
• /
• pp.55-60
• /
• 2009

This study was carried out to propose the optimum technologies that can be applicable to noise and fugitive dust controlling in construction sites by comparative analysis in cases. The ninety three environmental management technologies applied to fifty-five construction projects conducted during 2005~2007 in Korea were analyzed by checklist method. The construction companies paid more attention to the noise and fugitive dust controlling technologies than the waste and wastewater. The diverse pollution controlling techniques were applied to the architectural projects than the civil projects to meet the environmental requirements in residential area. The fugitive dust controlling technologies(75.3%) were more widely applied to all construction projects than the noise controlling technologies(24.7%). As the noise controlling techniques, the noise barriers in wall-form which are set up as boundary in construction site were more widely used than the noise barriers in curtain-form, in cabin and silencers. Water spraying systems, wind barriers and mechanical sweepers were the preferred technologies for controlling fugitive dust emission.