• Journal of KSNVE
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• v.9 no.6
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• pp.1137-1144
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• 1999

Most of ANC(active noise control) researches are focused on adaptive algorithms, computer simulations and implementations of single-channel system in experimental environments. In this paper, a multi-channel ANC system based on DSP's was developed to obtain global attenuations over wide region and applied to the active control of the humming noise generated by a transformer. The developed ANC system including 24 microphones and 12 spearkers was applied to the real transformer noise reduction problem. Results showed that the control system could successfully control the humming noise over the region of interest.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.306-314
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• 2003

Engineered barrier test facility is specially designed to demonstrate the performance of engineered barrier system for the near-surface disposal facility under the domestic environmental conditions. Comprehensive measurement systems for the water content, temperature, matric potential are installed within each test cell. In this study, short-term monitoring of the behavior of multi-layered cover system is implemented with artificial rainfall system. The periodic measurement data are collected and analyzed by a dedicated database management system, and provide a basis for performance verification of the disposal cover design.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.3
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• pp.63-70
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• 2013

Many real world optimization problems are discrete and multi-valued. Meta heuristics including Genetic Algorithm and Particle Swarm Optimization have been effectively used to solve these multi-valued optimization problems. However, extensive comparative study on the performance of these algorithms is still required. In this study, performance of these algorithms is evaluated with multi-modal and multi-dimensional test functions. From the experimental results, it is shown that Discrete Particle Swarm Optimization (DPSO) provides better and more reliable solutions among the considered algorithms. Also, additional experiments shows that solution quality of DPSO is not lowered significantly when bit size representing a solution increases. It means that bit representation of multi-valued discrete numbers provides reliable solutions instead of becoming barrier to performance of DPSO.

• Economic and Environmental Geology
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• v.56 no.2
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• pp.167-183
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• 2023

Gases originated from the final SNF (spent nuclear fuel) disposal site are very mobile in the barrier and they may also affect the migration of radioactive nuclides generated from the SNF. Mechanisms of gas-nuclide migration in the multi-barrier and their influences on the safety of the disposal site should be understood before the construction of the final SNF disposal site. However, researches related to gas-nuclide coupled movement in the multi-barrier medium have been very little both at home and abroad. In this study, properties of gas generation and migration in the SNF disposal environment were reviewed through previous researches and their main mechanisms were summarized on the hydrogeological evolution stage of the SNF disposal site. Gas generation in the SNF disposal site was categorized into five origins such as the continuous nuclear fission of the SNS, the Cu-canister corrosion, the oxidation-reduction reaction, the microbial activity, and the inflow from the natural barriers. Migration scenarios of gas in porous medium of the multi-barrier in the SNF repository site were investigated through reviews for previous studies and several gas migration types including ① the free gas phase flow including visco-capillary two-phase flow, ② the advection and diffusion of dissolved gas in pore water, ③ dilatant two-phase flow, and ④ tensile fracture flow, were presented. Reviewed results in this study can support information to design the further research for the gas-nuclide migration in the repository site and to evaluate the safety of the Korean SNF disposal site in view points of gas migration in the multi-barrier.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1081-1085
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• 2002

A modeling is developed to predict the isolation performance of sound barrier systems under the sound pressure radiated from excited by point impact. The predicted results are compared with the measured results obtained by using APAMAT II. This instrument provides a combination of structure-borne noise and air-borne noise, which corresponds to rolling noise, by applying the excitation system projected steel balls against the steel sheet.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.85-89
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• 2004

The wave interactions with fully submerged and floating dual buoy/vertical porous membrane breakwaters has been investigated in experimentally to validate the developed theory and numerical method in the previous study, in which multi-domain hydro-elastic formulation was carried out in the context of linear wave-body interaction theory and Darcy's law. It is found that the experimental results agrees well with the numerical prediction. Transmission and reflection can be quite reduced simultaneously especially in the region of long waves. The properly tuned system to incoming waves can effectively dissipate wave energy and also offset each other between incident and scattered waves using its hydro-elasticity and geometry.

• Tunnel and Underground Space
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• v.34 no.5
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• pp.571-598
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• 2024

Nuclear power generation, which belongs to the eco-friendly energy category, has a comparative advantage over other power generation methods in terms of cost and efficiency, and its share of electricity energy has recently shifted to an increasing trend worldwide. In Korea, various empirical studies have been conducted centering on KURT (KEARI Underground Research Tunnel) to secure elemental technology necessary for safe and efficient disposal of high-level radioactive waste inevitably generated during the operation of nuclear power plants. Considering the domestic rock type and geological conditions, the multi-barrier system is evaluated as the most effective among various high-level radioactive waste disposal methods. The objectives of this study were, first, to evaluate the hydraulic characteristics of deep and low-permeable rock masses and second, to secure quantitative information on the hydraulic connectivity between boreholes for establishing a large-scale in-situ test system necessary for the proper design and stability evaluation of the multi-barrier system. In this regard, diverse borehole tests using DHTS (Deep borehole Hydraulic Testing System) were performed in the two research modules in KURT, and in particular, the injection type cross-hole hydraulic connectivity tests were successfully completed for the first time in Korea. In this paper, we briefly introduced MDST (Mini Downhole Shut-in Tool) developed to update the performance of DHTS and mainly discussed the key results obtained from the stepwise in-situ borehole tests.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.477-486
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• 2015

We propose a novel calibration method which can be applied to all kinds of panel-type multi-view displays. We analyze how the angular, the axial, and the lateral misalignment affects the 3D image quality in a panel-type multi-view display. We demonstrate the ray optics simulation with a 3-view slanted parallax barrier system using pentile display for the quantitative calculation. Based on the analysis, we propose a new alignment pattern for all kinds of panel-type multi-view displays. The proposed pattern is sensitive to all of the angular, the axial, and the lateral misalignments. The high spatial frequency images and on and off alignment in the proposed pattern help observers to calibrate the system easily. We theoretically show the generality of the proposed alignment pattern and verify the pattern with image simulations and experiments.

• Journal of Radiation Industry
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• v.17 no.4
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• pp.359-367
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• 2023

In this study, the function and purpose of the disposal cover, which is an engineering barrier installed to isolate the disposal vault of the near-surface disposal facility for radioactive waste from natural/man-made intrusion, and the design details of the demonstration facility for performance verification were described. The Demonstration facility was designed in a partially divided form to secure the efficiency of measurement while being the same as the actual size of the surface disposal facility to be built in the Intermediate & low-level radioactive waste disposal site of the Korea Radioactive Waste Agency (KORAD). The instruments used for measurement consist of a multi-point thermometer, FDR (Frequency Domain Reflectometry) sensor, inclinometer, acoustic sensor, flow meter, and meteorological observer. It is used as input data for the monitoring system. The 3D monitoring system was composed of 5 layers using the e-government standard framework, and was developed based on 4 components: screen, control module, service module, and DBIO(DataBase Input Output) module, and connected them to system operation. The monitoring system can provide real-time information on physical changes in the demonstration facility through the collection, analysis, storage, and visualization processes.

• Journal of the Korean Geotechnical Society
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• v.29 no.9
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• pp.71-80
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• 2013

This work studies the reliability analysis of a slope that considers multiple failure modes. The analysis consists of two parts. First, significant failure modes that contribute most to system reliability are determined. The so-called barrier method proposed by Der Kiureghian and Dakessian to identify significant failure modes successively is employed. Second, the failure probability for the slope is estimated on the basis of the identified significant failure modes and corresponding design points. For reliability problems entailing multiple design points, failure probability can be estimated by the multi-point first-order reliability method (FORM), Ditlevsen's bounds method, and Monte Carlo simulation. In this paper, a comparative study between these methods has been made through example problems. Analysis results showed that while a soil slope may have a large number of potential slip surfaces, its system failure probability is usually governed by a few significant slip surfaces. Therefore, the most important step in the system reliability analysis for a soil slope is to identify all the significant failure modes in an efficient way.