• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• Construction Engineering and Management
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• v.12 no.5
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• pp.43-54
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• 2011

LCC(Life Cycle Cost) analysis on design process has to be performed for a selection of reasonable and economical design alternatives in highway construction projects. To be performed of LCC analysis, the maintenance data such that are maintenance periods, rate of repair, maintenance cost, and so on are required. Therefore the Hi-Portal System had been developed and the maintenance data has been accumulating in the Korean Expressway Corporation. However, the data are not effectively used because the system have no consideration for LCC concept, and currently, th data are acquired by survey with experts. In the study, it is proposed that the concept of Generally Annual Maintenance are practically and easily used to perform LCC analysis. Some of generally annual maintenance data are suggested through Hi-portal data analysis due to the proposed concept and LCC analysis of a real highway construction project is preformed by comparison with a current approach. From the results, it make sure that the proposed concept are effectively used to preform LCC analysis until during exactly practical data from Hi-Portal system are obtained.

• The Korean Journal of Community Living Science
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• v.27 no.2
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• pp.281-294
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• 2016

This study was conducted to promote consumer interest in Geothermal Heat Pump (Ground Source Heat Pump, GSHP) and district heating and cooling (District Heating & Cooling, DHC) systems, which are competing with each other in the heating and cooling field. Considering not only the required cost data of energy itself, but also external influence factors, the optimal mix ratio of these two energy systems was studied as follows. The quantitative data of the two energy systems was entered into a database and the non-quantitative factors of external influence were applied in the form of coefficients. Considering both of these factors, the optimal mix ratio of GSHP and DHC systems and minimum Life Cycle Cost (LCC) were obtained using an algorithm model design. The Optimal Energy Mix of GSHP & DHC (OEMGD) algorithm was developed using a software program (Octave 4.0). The numerical result was able to reflect the variety of external influence factors through the OEMGD algorithm. The OEMGD model found that the DHC system is more economical than the GSHP system and was able to represent the optimal energy mix ratio and LCC of mixed energy systems according to changes in the external influences. The OEMGD algorithm could be of help to improve the consumers' experience and rationalize their energy usage.

• Journal of Korea Multimedia Society
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• v.8 no.10
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• pp.1391-1402
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• 2005

All industrial Products of today are various demand of customers and are switchovered the manufacturing system of a small quantity batch production. Its life cycle was very shortened. An enterprise is improved to satisfaction with external customers and internal customers of infinity competition time. They can exist on achieving customer satisfaction management. In this paper, a new implementation of service information system (SIS) with real time using RFID and X-Internet in Ubiquitous environments is proposed. The proposed SIS system has Web architecture based on XML and has a new X-Internet environment overcoming limitation of Client/server architecture. The service information system analyze its material data and suppress the same CLAIM creation. The implementation method of real time SIS system using RFID and X-Internet is proposed for contribution of business market reducing F-Cost.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.1-13
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• 2010

This paper proposes an optimal design method for the nonlinear seismic isolated bridge. The probabilities of failure at the pier and the seismic isolator are considered as objective functions for optimal design, and a multi-objective optimization technique is employed to efficiently explore a set of multiple solutions optimizing mutually-conflicting objective functions at the same time. In addition, a stochastic linearization method is incorporated into the multi-objective optimization framework in order to effectively estimate the stochastic responses of the bridge without performing numerous nonlinear time history analyses during the optimization process. As a numerical example to demonstrate the efficiency of the proposed method, the Nam-Han river bridge is taken into account, and the proposed method and the existing life-cycle-cost based design method are both applied for the purpose of comparing their seismic performances. The comparative results demonstrate that the proposed method not only shows better seismic performance but also is more economical than the existing cost-based design method. The proposed method is also proven to guarantee improved performance under variations in seismic intensity, in bandwidth and in the predominant frequency of the seismic event.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.3
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• pp.223-230
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• 2017

BIM(building information modeling) has been actively applied to construction industries and to maximize its application through the life cycle of structure, various relevant technologies have been proposed. In particular, 4D sequencing management and 5D cost-related management were introduced as an improved version of the design review and interface control by 3D information design. On the other hand, the virtual construction using virtual construction equipment can sophisticatedly handle capacity, dynamic movement, collision boundaries of actual construction machines but it still stays at a low level in a technical sense. In this study, simulation systems based on BIM involving virtual construction equipment have been developed; then it is applied to the actual construction project to evaluate the safety and efficiency of construction equipments. It was confirmed that the simulation systems can be utilized to construct virtual construction site by using an effective 3D library of construction equipment and can plays a key role to secure construction safety and economic feasibility. Specifically, the simulation system are very useful for decision making by construction managers to select the optimum equipment and construction method with a better understanding for safety and cost-saving.

• The KIPS Transactions:PartD
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• v.9D no.2
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• pp.259-266
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• 2002

The main issue in software development is the ability of software project effort and cost estimation in the early phase of software life cycle. The regression models for project effort and cost estimation are presented by function point that is a software sire. The data sets used to conduct previous studies are of ten small and not too recent. Applying these models to 789 project data developed from 1990 ; the models only explain fewer than 0.53 $R^2$(Coefficient of determination) of the data variation. Homogeneous group in accordance with project delivery rate (PDR) divides the data sets. Then this paper presents general effort estimation models using project delivery rate. The presented model has a random distribution of residuals and explains more than 0.93 $R^2$ of data variation in most of PDR ranges.