• Ceramist
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• v.21 no.4
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• pp.331-348
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• 2018

With the expectation to overcome the problem of increasing energy consumption, polymer electrolyte membrane fuel cells are getting more attention as a promising environmentally friendly and sustainable next-generation energy conversion system. In spite of the rapid improvement of polymer electrolyte membrane fuel cells(PEMFCs), there are several critical issues still need to be resolved for practical commercialization. Out of the many issues, the main hurdle comes from oxygen reduction reaction(ORR), thus development of efficient ORR electrocatalysts is the main key for enhancing PEMFC performance. Among various catalysts, 1D nanostructured catalyst is a promising candidate because it holds many advantages that come from nanostructuring while supplementing the disadvantages of other nanostructures such as nanoparticles(0D) or gyroids(3D). This review focused on diverse 1D nanostructures and talks about their advantages as catalyst for ORR. Different 1D nanostructures will be introduced while applying the structures to different materials system showing the prospects of 1D nanostructures for improving PEMFC.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.577-584
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• 2005

There are many activities involved in promoting renewable energy technologies. These include governments, the renewable energy manufacturing and service industries, energy supply companies, investors, researchers, non-government organizations and customers. For a sustainable renewable energy market, finding a promising industry is essential. The industry has made significant progress in recent years, considering the fact that today's renewable energy market is relatively small. This paper analyses the technology market of renewable energy, focusing on photovoltaic system, fuel cell, wind system. It appears that there has been remarkable progress in renewable energy systems. Besides, developed countries are effectively increasing the share of niche market and promoting renewable energy worldwide.

• Smart Structures and Systems
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• v.16 no.3
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• pp.521-535
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• 2015

Vibration-based monitoring is one approach used to perform structural condition assessment. By measuring structural response, such as displacement, dynamic characteristics of a structure may be estimated. Often, the primary dynamic responses in civil structures are below 5 Hz, making accurate low frequency measurement critical for successful dynamic characterization. In addition, static deflection measurements are useful for structural capacity and load rating assessments. This paper presents a DC coupled continuous wave radar to accurately detect both dynamic and static displacement. This low-cost radar sensor provides displacement measurements within a compact, wireless unit appropriate for a range of structural monitoring applications. The hardware components and operating mechanism of the radar are introduced and a series of laboratory experiments are presented to assess the performance characteristics of the radar. The laboratory and field experiments investigate the effect of factors such as target distance, motion amplitude, and motion frequency on the radar's measurement accuracy. The results demonstrate that the radar is capable of both static and dynamic displacement measurements with sub-millimeter accuracy, making it a promising technology for structural health monitoring.

• Computers and Concrete
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• v.10 no.4
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• pp.391-407
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• 2012

Utilization of supplementary cementing materials (SCM) by the cement industry, as a highly promising solution of sustainable cement development aiming to reduce carbon dioxide emissions, necessitates a more thorough evaluation of these types of materials on concrete durability. In this study a comparative assessment of the effect of SCM on concrete durability, of every cement type as defined in the European Standard EN 197-1 is taking place, using a software tool, based on proven predictive models (according to performance-related methods for assessing durability) developed and wide-validated for the estimation of concrete service life when designing for durability under harsh environments. The effect of Type II additives (fly ash, silica fume) on CEM I type of cement, as well as the effect of every Portland-composite type of cement (and others) are evaluated in terms of their performance in carbonation and chloride exposure, for a service life of 50 years. The main aim is to portray a unified and comprehensive evaluation of the efficiency of SCM in order to create the basis for future consideration of more types of cement to enter the production line in industry.

• Advances in concrete construction
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• v.5 no.4
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• pp.331-343
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• 2017

In this study a polymer concrete, made up of natural aggregates and an orthophthalic polyester binder, reinforced with natural Alfa fibers has been studied. The results of flexural testing of unreinforced polymer concrete with different rates of charges (marble) showed that the concrete with 20% of marble is stronger and more rigid compared to other grades. Hence, a rate of 20% of marble powder is selected as the optimal value in the development of polymer concrete reinforced Alfa fibers. The fracture results of reinforced polymer concrete with 1 and 2 wt% of chopped untreated or treated Alfa fibers showed that treated Alfa (5% NaOH) fiber reinforced polymer concrete has higher fracture properties than other composites. We believe that this type of concrete provides a very promising alternative for the building industry seeking to achieve the objectives of sustainable development.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2081-2101
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• 2016

Successive interference cancellation (SIC) is considered to be a promising technique to mitigate multi-user interference and achieve concurrent uplink transmissions, but the optimal power allocation (PA) issue for SIC users is not well addressed. In this article, we focus on the optimization of the PA ratio of users on an SIC channel and analytically obtain the optimal PA ratio with regard to the signal-to-interference-plus-noise ratio (SINR) threshold for successful demodulation and the sustainable demodulation error rate. Then, we design an efficient resource allocation (RA) scheme using the obtained optimal PA ratio. Finally, we compare the proposal with the near-optimum RA obtained by a simulated annealing search and the RA scheme with random PA. Simulation results show that our proposal achieves a performance close to the near-optimum and much higher performance than the random scheme in terms of total utility and Jain's fairness index. To demonstrate the applicability of our proposal, we also simulate the proposal in various network paradigms, including wireless local area network, body area network, and vehicular ad hoc network.

• Journal of Powder Materials
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• v.28 no.2
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• pp.150-163
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• 2021

Interest in eco-friendly materials with high efficiencies is increasing significantly as science and technology undergo a paradigm shift toward environment-friendly and sustainable development. MXenes, a class of two-dimensional inorganic compounds, are generally defined as transition metal carbides or nitrides composed of few-atoms-thick layers with functional groups. Recently MXenes, because of their desirable electrical, thermal, and mechanical properties that emerge from conductive layered structures with tunable surface terminations, have garnered significant attention as promising candidates for energy storage applications (e.g., supercapacitors and electrode materials for Li-ion batteries), water purification, and gas sensors. In this review, we introduce MXenes and describe their properties and research trends by classifying them into two main categories: transition metal carbides and nitrides, including Ti-based MXenes, Mo-based MXenes, and Nb-based MXenes.

• Journal of Korean Society of Forest Science
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• v.111 no.2
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• pp.330-344
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• 2022

While deforestation and forest degradation has continued globally, global society has been making efforts to prevent deforestation towards sustainable development. Reforestation in developing countries is linked to Sustainable Development Goals (SDGs) such as climate change mitigation, conservation of biodiversity, eradication of poverty and upholding of human rights. Forest official development assistance (ODA) restores the global forest land, and increases the public benefit. Bilateral forest ODA projects of the Republic of Korea have gradually increased and most of those projects have currently been concentrated in Asian countries. Selecting recipient countries for forest ODA requires more comprehensive approach since the global goals for sustainable development has been widely adapted to ODA strategic plans. We proposed potentially promising countries that are eligible for receiving 'Green ODA' in perspective of economic, social and environment to implement reducing emissions from deforestation and degradation (REDD+), conserving biodiversity, and combating desertification. As a result, the study suggests that forestry cooperation could be expanded from Asian countries more toward South America and African countries. In addition, we emphasized the need to promote convergence and integration with green technology to fundamentally solve the negative impacts of deforestation such as food, energy, water resource shortages, and forest fires. We advocated expanding bilateral ODA in the forestry sector through diversification of project activities, financial sources, and participants. Our study can contribute to the provision of basic information for establishing long-term strategies to expand bilateral cooperation in the forestry sector.

• Analytical Science and Technology
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• v.36 no.5
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• pp.236-249
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• 2023

Carbon dioxide (CO₂) capture and storage is a critical issue for mitigating climate change. Porous aromatic Schiff base complexes have emerged as a promising class of materials for CO₂ capture due to their high surface area, porosity, and stability. In this study, we investigate the potential of Schiff base complexes as an effective media for CO₂ storage. We review the synthesis and characterization of porous aromatic Schiff bases materials complexes and examine their CO₂ sorption properties. We find that Schiff base complexes exhibit high CO₂ adsorption capacity and selectivity, making them a promising candidate for use in carbon capture applications. Moreover, we investigate the effect of various parameters such as temperature, and pressure on the CO₂ adsorption properties of Schiff base complexes. The Schiff bases possessed tiny Brunauer-Emmett-Teller surface areas (4.7-19.4 m²/g), typical pore diameters of 12.8-29.43 nm, and pore volumes ranging from 0.02-0.073 cm³/g. Overall, our results suggest that synthesized complexes have great potential as an effective media for CO₂ storage, which could significantly reduce greenhouse gas emissions and contribute to mitigating climate change. The study provides valuable insights into the design of novel materials for CO₂ capture and storage, which is a critical area of research for achieving a sustainable future.

• Journal of Information Technology Applications and Management
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• v.21 no.4_spc
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• pp.431-447
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• 2014

Demand of spectrum resource is tremendously increasing and this trend will continue as more IT services such as cloud computing, smart devices, Internet of Things are provided through wireless network. Recent development of spectrum sharing technology has drawn attention to spectrum policy makers as a promising way to overcome the expected spectrum shortage problem. However, technology-based solution to spectrum shortage problem may not be sustainable since the solution affect only one aspect of spectrum sharing ecosystem. To understand the whole picture of spectrum shortage problem, policies to vitalize spectrum sharing ecosystem were proposed based on the analysis of System Dynamics causal map in the previous study. This study compares and analyzes the effect of those proposed vitalization policies by using System Dynamics simulation. Among seven alternative policies, combined application of demand acceleration policy and technology development policy was found to be more effective for better utilization of spectrum. The effect of demand acceleration policy was offset when other policies are applied together except supply acceleration policy which shows better spectrum sharing.