• Clean Technology
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• v.10 no.1
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• pp.9-17
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• 2004

Direct methanol fuel cell(DMFC) with proton exchange membrane (PEM) has advantages over the conventional power source (e.g. vehicle). DMFC, however, has a problem to be solved such as methanol crossover, high anodic overpotential and limiting current density, etc. The physicochemical phenomena in DMFC can be described by coupled PDEs (partial differential equations), which can be solved by a PDE solver. In this paper, we utilized a commercial software FEMLAB to solve the PDEs. The FEMLAB is one of the software programs available which are developed as a solver for building physics problems based on PDEs and is designed to simulate systems of coupled PDEs which may be 1D, 2D, 3D, non-liner and time dependent. We performed simulation using the Tafel equation as an electrochemical reaction model to analyze methanol concentration profile in DMFC system. We confirm that the rapid decrease of methanol concentration at anodic catalyst layer with the increase of the current density is a main reason of the low performance in DMFC through simulation results.

• Safety and Health at Work
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• v.7 no.4
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• pp.331-339
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• 2016

Background: Occupational risk management is known as a catalyst in generating superior returns for all stakeholders on a sustainable basis. A number of companies in Ghana implemented health and safety measures adopted from international companies to ensure the safety of their employees. However, there exist great threats to employees' safety in these companies. The purpose of this paper is to investigate the level of compliance of Occupational Health and Safety management systems and standards set by international and local legislation in power producing companies in Ghana. Methods: The methodology is conducted by administering questionnaires and in-depth interviews as measuring instruments. A random sampling technique was applied to 60 respondents; only 50 respondents returned their responses. The questionnaire was developed from a literature review and contained questions and items relevant to the initial research problem. A factor analysis was also carried out to investigate the influence of some variables on safety in general. Results: Results showed that the significant factors that influence the safety of employees at the hydroelectric power plant stations are: lack of training and supervision, non-observance of safe work procedures, lack of management commitment, and lack of periodical check on machine operations. The study pointed out the safety loopholes and therefore helped improve the health and safety measures of employees in the selected company by providing effective recommendations. Conclusion: The implementation of the proposed recommendations in this paper, would lead to the prevention of work-related injuries and illnesses of employees as well as property damage and incidents in hydroelectric power plants. The recommendations may equally be considered as benchmark for the Safety and Health Management System with international standards.

• Preventive Nutrition and Food Science
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• v.15 no.1
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• pp.57-66
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• 2010

Passion fruit fiber pectin gels represent a new alternative pectin source with potential for food and non-food applications on a commercial scale. Pectic polysaccharides were extracted from passion fruit (Passiflora edulis) fiber using citric acid as a clean catalyst and autoclaved for 20 to 60 min at $121^{\circ}C$. The best condition of pectin yield with the highest molecular weight was obtained with 1.0% of citric acid (250 mg/g dry passion fruit fiber pectin) for 20 min of autoclaving. Spectroscopic analyses by Fourier transform infrared, enzymatic degradation reactions, and ion-exchange chromatography assays showed that passion fruit pectin extracted for 20 min was homogeneous high methoxylated pectin (70%). Gel permeation analysis confirmed that the pectin extract obtained by autoclaving by 20 min showed higher molecular weights than those autoclaved for 40 and 60 min. Passion fruit pectin extracted for 20 min was enzymatically modified with fungal pectinmethylesterase to create restructured gels. Short autoclave treatment (20 min) with citric acid as extractant resulted in a significant increase of gel strength, improving pectin extraction in terms of functionality. The treatment of solubilized material (pectic polysaccharides) in the presence of insoluble material (cellulose and hemicellulose) with pectinmethylesterase and calcium led to the creation of a stiffer passion fruit fiber pectin gel, while syneresis was not observed.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.575-580
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• 2017

Chlorinated hydrocarbons (TCE and PCE), petroleum hydrocarbons (BTEX, PAHs, and TPH), and explosive compounds (TNT, RDX, and HMX) have been detected in underground water countrywide. The overall objective of this study is to evaluate sono-catalytic degradation coupled with the use of PUV in order to understand the fate and transport of a representative selection of non-biodegradable contaminants (i.e., TCE, PCE, BTEX, PAHs, TPH, TNT, RDX, and HMX) in groundwater. Both ultraviolet (UV) and ultrasound (US) systems are used in degrading of organic contaminants and they can thus be applicable simultaneously as an UV/US hybrid system in attempts further to increase the degradation efficiency. Results indicate that synergistic effect of UV/US hybrid system is closely correlated to the enhancement of sono-chemical reactivity with the UV-US interaction of increasing the formation rate of OH by providing additional $H_2O_2$ production through the pyrolysis of water molecules during UV/US hybrid irradiation.

• Resources Recycling
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• v.18 no.5
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• pp.12-18
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• 2009

The 20% Pt/C catalysts were synthesized using the chemical reduction method for polymer electrolyte fuel cell cathode and were heat-treated in the temperature range from 300 to $600^{\circ}C$. The oxygen reduction reaction of the catalysts was evaluated using the electrochemical measurement. The oxygen reduction reaction of the heat-treated Pt/C at $300^{\circ}C$ had high catalytic activity and the oxygen reduction reaction current of that was 2 times than that of non-heat treatment catalyst. It is considered that the change of the crystallinity and particle size by heat treatment could increase the catalytic activity.

• Polymer(Korea)
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• v.37 no.3
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• pp.379-386
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• 2013

SAPO-11 was applied for the first time to the catalytic pyrolysis of miscanthus and random polypropylene (random PP). Thermogravimetric analysis confirmed that SAPO-11 promoted the dehydration of miscanthus while suppressing the formation of char. In the pyrolysis of random PP, the decomposition temperature and activation energy were reduced by using a catalyst. A large fraction of levoglucosan, which was the main oxygenate product from the non-catalytic pyrolysis of miscanthus, was converted to high value-added products, such as furans, phenolics and aromatics using SAPO-34. The catalytic pyrolysis of random PP produced gasoline- and diesel-range hydrocarbons.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.117-121
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• 2018

A stainless steel mesh was applied to the cathode of an electro-Fenton system. Methylene blue (MB) solution was chosen as the model waste water with non-biodegradable pollutants. For the model waste water, the degradation efficiency was compared among various SUS mesh cathodes with different surface treatments and magnetite coatings on them. With increasing amount of the magnetite coating on SUS mesh, the degradation efficiency also increased. The improved electro-catalytic characteristic was explained by the increased amount of in situ generated hydrogen peroxide near the cathode surface. Cyclic voltammetry data also showed improved electro-catalytic performance for SUS mesh with more magnetite coatings on them.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.245-251
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• 2017

In this study, ZnO, which is widely known as a non $TiO_2$ photocatalyst, was synthesized using coprecipitation method and Ag was added in order to improve the catalytic performance. The physicochemical characteristics of the synthesized ZnO and Ag/ZnO particles were checked using X-ray diffraction (XRD), UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL), and photocurrent measurements. The performance of catalysts was tested by $H_2$ production using the photolysis of $H_2O$ with MeOH. By adding Ag which plays a role as an electron capture on the ZnO catalyst, the performance increased due to the recombination of excited electrons and holes. In particular, $8.60{\mu}mol\;g^{-1}$ $H_2$ was produced after 10 h reaction over the 0.50 mol% Ag/ZnO.

• Korean Institute of Interior Design Journal
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• no.22
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• pp.61-68
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• 2000

This paper illustrates what the reality of architectural concepts, materials, notions and phenomena are as central questions of contemporay space design. These issues form the goal of modern space design which should attain to the reality of an era when non-real values prevail. Despite the trends of an everchanging and ephemeral dominating quality in architecture for the last ten years, architects still aim to contruct everlasting space on earth. The trends of dematerialization in today's space design can be substantiated in spatial-temporal dimensions as follows. First of all, ephemeral architecture with concepts of hypothetical temporality, everchanging architecture in fluidity, and the transparent architecture with the floating and overlapping image can be analyzed in the dimension of 'time'. In terms of 'space', void quality for the expression of emptiness, neutral space by the simplified and summarized forms, expanded space through ambiguous boundaries and spatial repetition can becharacterized and also be intended strategies for lightness, state of flux, ambiguity, paradox etc., lead modern space design along that path. As this point, we need to pay attention to the so-called 'hypersurface' concept proposed by Stephen Perella. Hypersurface is a sort of cladding sheathing existence independent from the primary structure. With it, the integration between form and image can be achieved. Sometimes hypersurface can be a strategical screen for image projection, a cognitive receptor for surroundings as well as a catalyst for information and communication systems. When the situation dematerializes more and more as the years go on, the concept of hypersurface can be an inclusive method between the phenomenological form in architecture and its self recipient image. Permissive atmospheres created between them in contemporary space design and new paradigms emerged with digital technology will further reinforce the human space's dynamism.

• Polymer(Korea)
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• v.29 no.4
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• pp.338-343
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• 2005

The thermal degradation of ABS/PC/triphenyl phosphate compounds in the presence of transition metal chloride catalysts has been studied by thermogravimetric analysis (TGA). The reaction of transition metal chloride catalysts (cobalt chloride, ferric chloride, nickel chloride and zinc chloride) and ABS/PC/triphenyl phosphate compounds has been found to occur during the thermal degradation of the compounds. In a nitrogen atmosphere, char formation is observed, and $3\~13\%$of the reaction product is non-volatile at $600^{circ}$. The resulting enhancement of char formation in a nitrogen atmosphere has been explained as a catalytic crosslinking effect of transition metal chloride catalysts. On the other hand, transition metal chloride catalyzed char formation of ABS/PC/triphenyl phosphate compounds in air was unsuccessful due to the oxidative degradation of the char at a higher temperature.