• Economic and Environmental Geology
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• v.55 no.6
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• pp.737-760
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• 2022

For the geological disposal of high-level radioactive wastes (HLW), an understanding of deep subsurface environment is essential through geological, hydrogeological, geochemical, and geotechnical investigations. Although South Korea plans the geological disposal of HLW, only a few studies have been conducted for characterizing the geochemistry of deep subsurface environment. To guide the hydrogeochemical research for selecting suitable repository sites, this study overviewed the status and trends in hydrogeochemical characterization of deep groundwater for the deep geological disposal of HLW in developed countries. As a result of examining the selection process of geological disposal sites in 8 countries including USA, Canada, Finland, Sweden, France, Japan, Germany, and Switzerland, the following geochemical parameters were needed for the geochemical characterization of deep subsurface environment: major and minor elements and isotopes (e.g., ³⁴S and ¹⁸O of SO₄^2-, ¹³C and ¹⁴C of DIC, ²H and ¹⁸O of water) of both groundwater and pore water (in aquitard), fracture-filling minerals, organic materials, colloids, and oxidation-reduction indicators (e.g., Eh, Fe²⁺/Fe³⁺, H₂S/SO₄^2-, NH₄⁺/NO₃^-). A suitable repository was selected based on the integrated interpretation of these geochemical data from deep subsurface. In South Korea, hydrochemical types and evolutionary patterns of deep groundwater were identified using artificial neural networks (e.g., Self-Organizing Map), and the impact of shallow groundwater mixing was evaluated based on multivariate statistics (e.g., M3 modeling). The relationship between fracture-filling minerals and groundwater chemistry also has been investigated through a reaction-path modeling. However, these previous studies in South Korea had been conducted without some important geochemical data including isotopes, oxidationreduction indicators and DOC, mainly due to the lack of available data. Therefore, a detailed geochemical investigation is required over the country to collect these hydrochemical data to select a geological disposal site based on scientific evidence.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.7
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• pp.523-528
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• 2020

A lateral type MEMS inertial switch was designed on the same principle as spring-mass system. The MEMS switch is used for arming mechanism of the arm-fire device by sensing the applied acceleration. We analyzed the switching capability of the MEMS switch under various acceleration conditions via performance model. Simulation results showed that the MEMS switch works very well at 10 g when the applied acceleration slope does not exceed 10 g/msec. On the other hand, the threshold operating acceleration level simulation exceeded the requirement (10±2 g) due to the width and length of the spring by considering 10% tolerance of the design values. Design modification of doubling the width of the spring, which is difficult to reduce less than 10% tolerance in fabrication process, was proposed after confirming the simulation results comply the requirement.

• Journal of Environmental Science International
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• v.16 no.5
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• pp.533-539
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• 2007

The research was conducted to simulate and interpret the change of $PM_{10}$ profile by Asian dust using the CALPUFF modeling system for the period April 6 through 18, 2001. The results, which are represented a daily variation of $PM_{10}$ concentration before and after Asian dust, was located between a minimum concentration of $50{\mu}g/m^3$ and a maximum concentration of $100{\mu}g/m^3$, Most concentration peaks in the $PM_{10}$ profile were shown within a level below 500 m and had a pattern that rapidly increased up the peak and decreased after the peak to 1000 m. Even though the shapes of the vertical profile during Asian dust days were similar to non-Asian dust days, no rapid change vertically was observed. In particular, the vertical profile on 1200 LST and 1800 LST was noticeably shifted to the higher concentrations, which means $PM_{10}$ in the atmosphere was changed into a vertically and horizontally heterogeneous form under the Asian dust event. Finally, it is con-firmed that the simulation result from CALPUFF might schematically sketched atmospheric $PM_{10}$ profiles and their change by Asian dust throughout the comparison with profiles of aerosol extinction coefficients, which were acquired from Lidar measurement at KGAWO.

• The Journal of Engineering Geology
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• v.33 no.2
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• pp.323-334
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• 2023

The vast volumes of data that are generated during site characterization and associated research for the disposal of high-level radioactive waste require effective data management to properly chronicle and archive this information. The Swedish Nuclear Fuel and Waste Management Company, SKB, established the SICADA database for site selection, evaluation, analysis, and modeling. The German Federal Company for Radioactive Waste Disposal, BGE, established ArbeitsDB, a database and document management system, and the ELO data system to manage data collected according to the Repository Site Selection Act. The U.K. Nuclear Waste Services established the Data Management System to manage any research and survey data pertaining to nuclear waste storage and disposal. The U.S. Department of Energy and Office of Civilian Radioactive Waste Management established the Technical Data Management System for data management and subsequent licensing procedures during site characterization surveys. The presented cases undertaken by these national agencies highlight the importance of data quality management and the scalability of data utilization to ensure effective data management. Korea should also pursue the establishment of both a data management concept for radioactive waste disposal that considers data quality management and scalability from a long-term perspective and an associated data management system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.236-242
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• 2019

Recently, scanning projects have been carried out in various construction and construction fields for maintenance purposes. The point cloud generated by the scan results is composed of a number of points representing the object to be scanned. The process of extracting the necessary information, including dimensions, from such scan data is called paradox. The reverse engineering process of modeling a point cloud as BIM involves considerable manual work. Owing to the time-consuming reverse engineering nature of the work, the costs increase exponentially when rework requests are made, such as design changes. Reverse engineering automation technology can help improve these problems. On the other hand, the reverse design product is variable depending on the use, and the kind and detail level of the product may be different. This paper proposes the G2BM (Geometry-to-BIM mapping) rule definition method that automatically maps a BIM object from a primitive geometry to a BIM object. G2BM proposes a process definition and a customization method for reverse engineering BIM objects that consider the use case variability.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.10
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• pp.1-9
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• 2004

User-Perceived application-level performance is a key to the adoption and success of CDMA 2000. To predict this performance in advance, a detailed end-to-end simulation model of a CDMA network was built to include application traffic characteristics, network architecture, network element details, and protocol features. We assess the user application performance when a Radio Access Network (RAN) and a Core Network (CN) adopt different transport architectures such as ATM and If. For voice Performance, we found that the vocoder bypass scenario shows 8% performance improvement over the others. For data packet performance, we found that HTTP v.1.1 shows better performance than that of HTTP v.1.0 due to the pipelining and TCP persistent connection. We also found that If transport technology is better solution for higher FER environment since the IP packet overhead is smaller than that of ATM for web browsing data traffic, while it shows opposite effect to small size voice packet in RAN architecture. Though simulation results we showed that the 3G-lX EV system gives much better packet delay performance than 3G-lX RTT, the main conclusion is that end-to-end application-level performance is affected by various elements and layers of the network and thus it must be considered in all phases of the technology evolution process.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.4
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• pp.1282-1301
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• 2015

Traditional infrastructure has been superseded by cloud computing, due to its cost-effective and ubiquitous computing model. Cloud computing not only brings multitude of opportunities, but it also bears some challenges. One of the key challenges it faces is recovery of computing nodes, when an Information Technology (IT) failure occurs. Since cloud computing mainly depends upon its nodes, physical servers, that makes it very crucial to recover a failed node in time and seamlessly, so that the customer gets an expected level of service. Work has already been done in this regard, but it has still proved to be trivial. In this study, we present a Cost-Time aware Genetic scheduling algorithm, referred to as CTaG, not only to globally optimize the performance of the cloud system, but also perform recovery of failed nodes efficiently. While modeling our work, we have particularly taken into account the factors of network bandwidth and customer's monetary cost. We have implemented our algorithm and justify it through extensive simulations and comparison with similar existing studies. The results show performance gain of our work over the others, in some particular scenarios.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.30-35
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• 2022

In a nuclear reactor, gamma radiation is the dominant energy deposition in non-fuel regions. Heat is generated upon gamma deposition and consequently affects the mechanical and thermal structure of the material. Therefore, the safety of samples should be carefully considered so that their integrity and quality can be retained. To evaluate relevant parameters, an in-core gamma thermometer (GT) was used to measure gamma heating (GH) throughout the operation of the McMaster nuclear reactor (MNR) at four irradiation sites. Additionally, a Monte Carlo reactor physics code (Serpent-2) was utilized to model the MNR with the GT located in the same irradiation sites used in the measurement to verify its predictions against measured GH. This research aids in the development of modeling, calculation, and prediction of the GH utilizing Serpent-2 as well as implementing a new GH measurement at the MNR core. After all uncertainties were quantified for both approaches, comparable GH profiles were observed between the measurements and calculations. In addition, the GH values found in the four sites represent a strong level of radiation based on the distance of the sample from the core. In this study, the maximum and minimum GH values were found at 0.32 ± 0.05 W/g and 0.15 ± 0.02 W/g, respectively, corresponding to 320 Sv/s and 150 Sv/s. These values are crucial to be considered whenever sample is planned to be irradiated inside the MNR core.

• Journal of the Korean Electrochemical Society
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• v.23 no.2
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• pp.39-46
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• 2020

Composite electrodes for rechargeable batteries generally consist of active material, electric conductor, and polymeric binder. And their composition and distribution within the composite electrode determine the electrochemical activity in the electrochemical systems. However, it is not easy to quantify the physical properties of composite electrodes themselves using conventional experimental analysis tools. So, 3D structural modeling and simulation can be an efficient design tool by looking into the contact areas between particles and electric conductivity within the composite electrode. In this study, while maintaining the composition (LiCoO₂ : Super P Li^® : Polyvinylidene Fluoride (PVdF) = 93 : 3 : 4 by wt%) and loading level (13 mg cm^-2) of the composite electrode, the effects of LiCoO₂ size (10 ㎛ and 20 ㎛) and electrode density (2.8 g cm^-3, 3.0 g cm^-3, 3.2 g cm^-3, 3.5 g cm^-3, 4.0 g cm^-3) on the physical properties are investigated using a GeoDict software. With this tool, the composite electrode can be efficiently designed to optimize the contact area and electric conductivity.

• Geomechanics and Engineering
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• v.18 no.4
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• pp.339-352
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• 2019

Rockmass parameters are used in the design of engineering structures built in rock and soil. One of the most important of these parameters is the rockmass Emass (Emass). Determination of the Emass of rockmass is a long, hard and expensive job. Therefore, empirical formulas developed by different researchers are used. These formulas use the elastic modulus of the material as a parameter. This value is a constant value in the design. However, engineering structures remain under different loads depending on many factors, such as topography, geometry of the structure, rock / soil properties. Time is other important parameter for rock/soil structure. With the start of the excavation, the loads that the structure is exposed to will change and remain constant at one level. In the new proposed method, the use of different Emass calculated from empirical formulas using the different material elastic modulus, which has different values under different loads as time dependent, was investigated in rock/soil structures during design. The performance of the stability analysis using different deformation modules was questioned by numerical modeling method. For this query, a sub-routine which can be integrated into the numerical modeling software has been developed. The integrated sub-routine contains the formula for the Emass, which is calculated from the material elasticity modules under time dependent and different constant loads in the laboratory. As a result of investigations conducted in 12 different field studies, the new proposed method is very sensitive.