• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.626-629
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• 2018

Fuel cell is one of the promising electrochemical technologies enabling power production with various fuel sources such as hydrogen, hydrocarbon and even solid carbon. However, its long-term performance is often unstable and unpredictable. In this work, we observed that gasification-driven hydrocarbons were the culprit of unpredictability. Therefore, we controlled the presence of hydrocarbons with the help of external gas supply, i.e. argon and carbon dioxide, and suggested the optimal amount of carbon dioxide required for predictable fuel cell operations. Our optimization strategy was based upon the following observations; carbon dioxide can work as both an inert gas and a fuel precursor, depending on its amount present in the reactor. When deficient, the carbon dioxide cannot fully promote the reverse Boudouard reaction that produces carbon monoxide fuel. When overly present, the carbon dioxide works as an inert gas that causes fuel loss. In addition, the excessive carbon monoxide may result in coking on the catalyst surface, leading to the decrease in the power performance.

• Membrane Journal
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• v.17 no.2
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• pp.93-98
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• 2007

The reliability of innovative membrane contactors technology (i.e. Gas/Liquid Membrane Contactors, Membrane Distillation/Crystallization) is today increasing for seawater desalination processes, where traditional pressure-driven membrane separation units are routinely operated. Furthermore, conventional membrane operations can be integrated with membrane contactors in order to promote possible improvements in process efficiency, operational stability, environmental impact, water quality and cost. Seawater is the most abundant aqueous solution on the earth: the amount of dissolved salts covers about 3% of its composition, and six elements (Na, Mg, Ca, K, Cl, S) account for more than 90% of ionic species. Recent investigations on Membrane Distillation-Crystallization have shown the possibility to achieve significant overall water recovery factors, to limit the brine disposal problem, and to recover valuable salts (i.e. calcium sulphate, sodium chloride, magnesium sulphate) by combining this technology with conventional RO trains. In this work, the kinetics of $CaSO_4{\cdot}2H_2O,\;NaCl\;and\;MgSO_4{\cdot}7H_2O$ crystallization is experimentally investigated in order to improve the design of the membrane-based crystallization unit.

• Applied Chemistry for Engineering
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• v.33 no.4
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• pp.352-366
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• 2022

Nuclear power plant operations for electricity generation, rare-earth mining, nuclear medical research, and nuclear weapons reprocessing considerably increase radioactive waste, necessitating massive efforts to eradicate radioactive waste from aquatic environments. Cobalt (⁵⁸Co) and strontium (⁹⁰Sr) radioactive elements have been extensively employed in energy generation, nuclear weapon testing, and the manufacture of healthcare products. The erroneous discharge of these elements as pollutants into the aquatic system, radiation emissions, and long-term disposal is extremely detrimental to humans and aquatic biota. Numerous methods for treating radioactive waste-contaminated water have emerged, among which the adsorption process has been promoted for its efficacy in eliminating radioactive waste from aquatic habitats. The current review discusses the adsorptive removal of radioactive waste from aqueous solutions using low-cost adsorbents, such as graphene oxide, metal-organic frameworks, and inorganic metal oxides, as well as their composites. The chemical modification of adsorbents to increase their removal efficiency is also discussed. Finally, the current state of ⁵⁸Co and ⁹⁰Sr removal performances is summarized and the efficiencies of various adsorbents are compared.

• The Journal of Economics, Marketing and Management
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• v.3 no.4
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• pp.21-27
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• 2015

With the recent increasing interest in sustainability management, the latest environmental report tends to be substituted by the expanded sustainability management report. In this work, I would like to introduce the management pattern of a global enterprise that values environmental soundness (environmental friendly) and implements eco-friendly measures. The enterprise chosen in this study is FedEx. In this article, FedEx case is presented how companies can adopt environmental friendly management in their businesses. FedEx has maintained an eco-friendly management since the introduction of the company's eco-friendly transport trucks in 2003, following its development in 2000. In 2005, it installed a solar power plant that can supply up to 80% of the electricity consumed by Oakland Logistics Center in California, USA. FedEx has published the "Global Enterprise Citizenship Report," which contains its business developments in 2009. FedEx has worked hard to minimize the influence caused by packaging of goods to the environment and appealed to customers to use recycled products as much as they can. FedEx also encourages customers to use packaging materials efficiently. A considerable amount of energy has been expended in the eco-friendly programs of FedEx. Although thousands of FedEx vehicles and aircraft operate daily with using large amounts of electricity and fuel, FedEx focuses on energy savings and global environment protection.

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2182-2189
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• 2004

In the recent years, environmentally conscious design and manufacturing technologies have attracted considerable attention. The coolants, lubricants, solvents, metallic chips and discarded tools from manufacturing operations will harm our environment and the earth's ecosystem. In the present work, the Tukey method of multiple comparisons is used to select the minimum level of coolant required in a turning process. The amount of coolant is varied in 270 designed experiments and the parameters cutting temperature, surface roughness, and specific cutting energy are carefully evaluated. The effects of coolant mix ratio as well as the amount of coolant on the turning process are studied in the present work. The cutting temperature and surface roughness for different quantity of coolant are investigated by analysis of variance (ANOVA) - test and a multiple comparison method. ANOVA-test results signify that the average tool temperature and surface roughness depend on the amount of coolant. Based on Tukey's Honestly Significant Difference (HSD) method, one of the multiple comparison methods, the minimum level of coolant is 1.0 L/min with 2% mix ratio in the aspect of controlling tool temperature. F-test concludes that the amount of coolant used does not have any significant effect on specific cutting energy. Finally, Tukey method ascertains that 0.5 L/min with 6% mix ratio is the minimum level of coolant required in turning process without any serious degradation of the surface finish. Considering all aspects of cutting, the minimum coolant required is 1.0 L/min with 6% mix ratio. It is merely half the coolant currently used i.e. 2.0 L/min with 10% mix ratio. Minimal use of coolant not only economically desirable for reducing manufacturing cost but also it imparts fewer hazards to human health. Also, sparing use of coolant will eventually transform the turning process into a more environment-conscious manufacturing process.

• Korean Journal of Construction Engineering and Management
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• v.8 no.3
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• pp.97-105
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• 2007

In many construction projects, such as dams, highways, airports, buildings, industrial plants, and sewerage and drainage systems earthmoving operation is defined the movements of a certain quantity of earth to alter the surface configuration or conditions so that projects requirement can be met. Accurate calculation of travel time is essential for determining productivity of earthmoving operations, and for ultimately selecting the most cost-effective fleet configuration for executing the work. Also transportation work that utilizes dump truck consists average So in the whole expenses earthmoving operation, and is an important cost factor for cost management. Therefore this study proposes a methodology for optimum transfer speen based on the analysis of factors affecting earthmoving operation in different road types by collecting the sources of dump truck running speeds and considering the main factors affecting the earthmoving operation.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.495-499
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• 2003

As an alternative to overcome the limitations of current popular schedule system such as Bar Chart, PERT, CPM in proving the feasibility of a given project schedule and duration, this research applies simulation to the 'Shiwha Techno-Valley project, and then reviews its usability in time management. Shiwha-Techno-Valley is a gigantic project requiring large number of equipment and resulting in traffic congestion. In particular, project site is located near the Shiwha industrial complex and Daeboo-Do tourist place. Therefore, current traffic needs should not be ignored. This research evaluates whether the project can be finished in a given time even if construction equipment increase in addition to the current traffic. Through the analysis of the simulation output, the research identifies the optimal resource input and the needs on alternative schedule for the project.

• Explosives and Blasting
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• v.22 no.3
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• pp.35-41
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• 2004

Many buildings have been bolt in Korea. Because blasting operations and more efficient to make excavate rock than other methods, it's more extensively used for new construction, enlargement of buildings, subway work, etc. However, blasting vibrations and sound often create pollution. A study, 'The place of gathering earth and sand to construct a building site in Yangsan', has been done in Gyo-dong, in Yangsan. There are two high-rise apartment and buildings, beside a construction site. The blasting vibrations and sound were monitored on the 1st, 4th floors in building(4th floor), and the results of the analysis are as follows: The blasting vibrations decreased being transmited from 1st floor to 4th floor.

• Advances in aircraft and spacecraft science
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• v.9 no.5
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• pp.449-462
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• 2022

Space-telescopes placed in the Sun-Earth second Lagrange point (L2) observe the sky following a scan strategy that is usually based on a spin-precession motion. Knowing which regions of the sky will be more observed by the instrument is important for the science operations and the instrument calibration. Computing sky observation parameters numerically (discretizing time and the sky) can consume large amounts of time and computational resources, especially when high resolution isrequired.This problem becomesmore critical if quantities are evaluated at detector level instead of considering the instrument entire Field of View (FoV). In previous studies, the authors have derived analytic solutions for quantities that characterize the observation of each point in the sky in terms of observation time according to the scan strategy parameters and the instrument FoV. Analytic solutions allow to obtain results faster than using numerical methods as well as capture detailed characteristics which can be overseen due to discretization limitations. The original approach is based on the analytic expression of the instrument trace over the sky. Such equations are implicit and thusrequiresthe use of numeric solversto compute the quantities.In this work, a new and simpler approach for computing one ofsuch quantities(mean observation time) is presented.The quantity is first computed for pure spin motion and then the effect of the spin axis precession is incorporated under the assumption that the precession motion is slow compared to the spin motion.In this sense, this new approach further simplifies the analytic approach, sparing the use of numeric solvers, which reduces the complexity of the implementation and the computing time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.1063-1076
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• 2017

To improve the productivity of the earthwork, a fleet management system for construction equipment was suggested in previous studies. But there were some gaps between theory and practice. To overcome this problem, some opinions are gathered form experts and field engineers and four improvements have been proposed and reflected in the system. First, the previous system consists of one hardware module, so it is hard to install it at a control office and construction equipment at the same time. The server module for the office and the mobile module for construction equipment are separately developed. Second, the transportation algorithm that is used in the previous system can generate shortest paths for the earthwork distribution, but embankment areas are not gathered. This situation leads to a decrease in compaction productivity. A modified algorithm for earthwork distribution is suggested. Third, the automated coordinate transformation is performed to show the position of construction equipment on the 3D terrain in real-time. Fourth, construction equipment groups should be formed in the initial stage of earthwork and the number of equipment of each groups should be changed by operation status and site environment. But this functions did not work properly in the previous system. This problem is corrected in the proposed system. The improvements can make the proposed system much more realistic one and can leads to an increase in the productivity of earthwork operations.