• Journal of National Security and Military Science
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• s.15
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• pp.117-151
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• 2018

The development of local defense parts has played a role a pure function such as maintenance of stable procurement source of military goods, provision of timely supply, establishment of self-defense base, creation of import substitution effect considering the whole life-cycle cost, reduction of foreign currency and protection of domestic defense industry. However, as the development success rate is deteriorating, it is time to analyze the related policies and improve the system. In order to improve the success rate of development of parts for the defense sector, it is necessary to unify the separated policies by the development-related departments and strengthen the policy support for the development companies to actively participate in the development. In addition, it is necessary to improve the paradigm for the selection of development items and change the authority of selecting development items and to delegate authority to create synergies. Parts localization development policy improvement is military support side it will contribute to strengthening defense power management by organically combining with technological development aspect and economical aspect. Development items will be linked to defense exports, which will have a remarkable effect on sales growth and job creation effects. The development of local defense parts is spreading.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.107-113
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• 2021

Plant Configuration Management(CM) is an activity to maintain consistency of design requirements, physical configuration, facility configuration information throughout the life cycle of the plant by systematically managing changes that occur during the plant design and operation process. Conformity between information must be ensured not only in the design stage, but also in the case of design changes in the operation and maintenance stages, and thus a computer system capable of efficiently managing them is required. In particular, in consideration of an application to small and medium-sized domestic plants, a computer system that can support configuration management at a low cost is needed. Accordingly, in this study, a configuration management system has been developed to support the management of plant design information and change procedures in the operation stage of small and medium-sized plants. Here, a case for quantitatively evaluating the effectiveness of the developed system is described.

• Corrosion Science and Technology
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• v.21 no.6
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• pp.445-453
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• 2022

SiO_x was prepared from a mixture of Si and SiO₂ via high-energy ball milling as a negative electrode material for Li-ion batteries. The molar ratio of Si to SiO₂ as precursors and the milling time were varied to identify the synthetic condition that could exhibit desirable anode performances. With an appropriate milling time, the material showed a unique microstructure in which amorphous Si nanoparticles were intimately embedded within the SiO₂ matrix. The interface between the Si and SiO₂ was composed of silicon suboxides with Si oxidation states from 0 to +4 as proven by X-ray photoelectron spectroscopy and electrochemical analysis. With the addition of a conductive carbon (Super P carbon black) as a coating material, the SiO_x/C manifested superior specific capacity to a commercial SiO_x/C composite without compromising its cycle-life performance. The simple mechanochemical method described in this study will shed light on cost-effective synthesis of high-capacity silicon oxides as promising anode materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.719-726
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• 2006

The use of CWR track not only reduces the track maintenance cost, but increase the life cycle of track components. Therefore, the use of the CWR track has increased consistently in the worldwide. As the use of CWR increases in track structures, derailing disasters associating with track buckling also increase in great numbers due to high compressive thermal stress in the summer. Among many CWR parameters, the influence of the sectional properties of the rail was investigated on the stability of CWR track in this study. Also, the sensitivity of the broken fastener and the stiffness of the fastener system such as the translational and rotational stiffness was investigated.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.375-385
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• 2013

As climate change and environmental pollution become one of the biggest global issues today, new renewable energy, especially solar photovoltaic (PV) system, is getting great attention as a sustainable energy source. However, initial investment cost of PV system is considerable, and thus, it is crucial to predict electricity generation accurately before installation of the system. This study analyzes the loss ratio of solar photovoltaic electricity generation from the actual PV system monitoring data to predict electricity generation more accurately in advance. This study is carried out with the following five steps: (i) Data collection of actual electricity generation from PV system and the related information; (ii) Calculation of simulation-based electricity generation; (iii) Comparative analysis between actual electricity generation and simulation-based electricity generation based on the seasonality; (iv) Stochastic approach by defining probability distribution of loss ratio between actual electricity generation and simulation-based electricity generation ; and (v) Case study by conducting Monte-Carlo Simulation (MCS) based on the probability distribution function of loss ratio. The results of this study could be used (i) to estimate electricity generation from PV system more accurately before installation of the system, (ii) to establish the optimal maintenance strategy for the different application fields and the different season, and (iii) to conduct feasibility study on investment at the level of life cycle.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.273-274
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• 2023

Although there are many old school buildings that is more than 40 years in Korea, it is difficult to rebuild all of them due to limitations in budget management. Therefore, objective feasibility evaluation criteria are necessary to determine which school buildings should be rebuilt preferentially among the numerous old school buildings. One of the rebuilding feasibility evaluation items, economic evaluation generally requires documents such as construction statements and facility drawings. However, because most buildings older than 40 years do not have these documents, an economic analysis model that requires only basic building information should be developed. In this study, the economic analysis model that can be used for evaluating the rebuilding feasibility only with the number of years, total floor area, and structural information of school buildings was established. This model can contribute to the objective feasibility evaluation of old school buildings because it can evaluate numerous buildings on the same criteria based on basic building information.

• Korea Trade Review
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• v.46 no.2
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• pp.121-140
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• 2021

The ship recycling or scrap is a phenomenon in the process of vessels life cycle has ended in the shipping industry. Scrap are greatly affected by freight rates due to ship demands. Not only that, environmental regulation and economic scale vessel demand are processes that must exist in the shipping industry as they obtain management for existing vessels. In the past, shipbreaking yard had tried to work without protection for poverty, without poor working conditions and facilities to prevent the emission of harmful substances. However, the issue of environmental pollution has been raised the Basel and Hong Kong Convention have been adopted, and a new replacement of the ship scrap that induces serious pollution is required. In this study, 165 countries were analyzed to confirm the importance of determining the ship solution. As a result of the analysis, it was found that the Environmental Performance Index, which is a measure of environmental regulation, is the most influential factor of ship scrapped volume. The determinant of whether lower labor cost can be secured is more correlated with population than GDP per capita. The implications of the results of the regression analysis mean that if environmental regulations for ship scrap of the future are strengthened, the status of Bangladesh and Pakistan, which currently account for half of the world's ship recycling, may change.

• Journal of the Korean institute of surface engineering
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• v.57 no.2
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• pp.57-70
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• 2024

Nickel-cobalt-manganese (NCM) lithium-ion batteries(LIBs) are increasingly prominent in the energy storage system due to their high energy density and cost-effectiveness. However, they face significant challenges, such as rapid capacity fading and structural instability during high-voltage operation cycles. Addressing these issues, numerous researchers have studied the enhancement of electrochemical performance through the coating of NCM cathode materials with substances like metal oxides, lithium composites, and polymers. Coating these cathode materials serves several critical functions: it acts as a protection barrier against electrolyte decomposition, mitigates the dissolution of transition metals, enhances the structural integrity of the electrode, and can even improve the ionic conductivity of the cathode. Ultimately, these improvements lead to better cycle stability, increased efficiency, and enhanced overall battery life, which are crucial for the advancement of NCM-based lithium-ion batteries in high-demand applications. So, this paper will review various cathode coating materials and examine the roles each plays in improving battery performance.

• Korean Journal of Construction Engineering and Management
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• v.17 no.5
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• pp.120-129
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• 2016

The user cost is an important analysis item which should be considered together with life-cycle of facility, administrator cost and discount rate in LCCA for efficient asset management of SOC facilities. Especially, a significant delay cost occurs often for users in the road field due to a work zone for cleaning and maintenance, and in such case, the administrator should consider the administrator cost as well as the user cost for more rational decision making. However, the user cost has not been considered in most decision making steps until recently and relevant studies also have not been carried out actively. In this study, the methodology to estimate the user cost and delay cost required in the decision making step using the traffic flow model and the direct benefit estimation model in the traffic facility investment evaluation guideline is suggested. And, the traffic flow model was estimated on 4 national highway sections where maintenance was actually carried out in 2014 using VISSIM and, the user cost and the delay cost were estimated based on the suggested methodology. The analysis result showed that the average user cost of $17,569,000KRW/km{\times}day$ occurred on Section A with approximately 30,000 AADT before a work zone occurred, and in case the first lane was blocked for maintenance, the delay cost of $10,193,000KRW/km{\times}day$ (158%) on average occurred additionally. The delay cost of $1,507,000KRW/km{\times}day$ (115%) and $1,985,000KRW/km{\times}day$ (119%) occurred on Sections B and D with approximately 20,000 AADT respectively and the delay cost of $262,000KRW/km{\times}day$ (105%) occurred on Section C with approximately 10,000 AADT. This result of this study was estimated based on the simulation of traffic flow model so that there is a limitation in its actual application. A study ot develop a highly appropriate model using actual observation data and improve the possibility to apply it through the verification using the simulation will be necessary in future.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.392.1-392.1
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• 2016

Nowadays, research interest in developing the wearable devices are growing remarkably. Portable consumer electronic systems are becoming lightweight, flexible and even wearable. In fact, wearable electronics require energy storage device with thin, foldable, stretchable and conformable properties. Accordingly, developing the flexible energy storage devices with desirable abilities has become the main focus of research area. Among various energy storage devices, supercapacitors have been considered as an attractive next generation energy storage device owing to their advantageous properties of high power density, rapid charge-discharge rate, long-cycle life and high safety. The energy being stored in pseudocapacitors is relatively higher compared to the electrochemical double-layer capacitors, which is due to the continuous redox reactions generated in the electrode materials of pseudocapacitors. Generally, transition metal oxides/hydroxide (such as $Co_3O_4$, $Ni(OH)_2$, $NiFe_2O_4$, $MnO_2$, $CoWO_4$, $NiWO_4$, etc.) with controlled nanostructures (NSs) are used as electrode materials to improve energy storage properties in pseudocapacitors. Therefore, different growth methods have been used to synthesize these NSs. Of various growth methods, electrochemical deposition is considered to be a simple and low-cost method to facilely integrate the various NSs on conductive electrodes. Herein, we synthesized amorphous $NiWO_4$ NSs on cost-effective conductive textiles by a facile electrochemical deposition. The as-grown amorphous $NiWO_4$ NSs served as a flexible and efficient electrode for energy storage applications.