• Journal of Digital Convergence
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• v.17 no.7
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• pp.131-138
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• 2019

The world's electricity production ratio is 40% for coal, 20% for natural gas, 16% for hydroelectric power, 15% for nuclear power and 6% for petroleum. Fossil fuels also cause serious problems in terms of price and supply because of the high concentration of resources on the earth. Solar energy is attracting attention as a next-generation eco-friendly energy that will replace fossil fuels with these problems. In this study, we test the charge-operation plan and the discharge operation plan for peak-cut operation by applying the maximum power demand reduction simulation. To do this, we selected the electricity usage from November to February, which has the largest amount of power usage, and applied charge / discharge logic. Simulation results show that the contract power decreases as the peak demand power after the ESS Peak-cut service is reduced to 50% of the peak-target power. As a result, the contract power reduction can reduce the basic power value of the customer and not only the economic superiority can be expected, but also contribute to the improvement of the electric quality and stabilization of the power supply system.

• Journal of Marine Bioscience and Biotechnology
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• v.14 no.2
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• pp.133-142
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• 2022

The increased production and consumption of polyethylene terephthalate (PET)-based products over the past several decades has resulted in the discharge of countless tons of PET waste into the marine environment. PET microparticles resulting from the physical erosion of general PET wastes end up in the ocean and pose a threat to the marine biosphere and human health, necessitating the development of new technologies for recycling and upcycling. Notably, enzyme-mediated PET degradation is an appealing option due to its eco-friendly and energy-saving characteristics. PETase, a PET-hydrolyzing enzyme originating from Ideonella sakaiensis, is one of the most thoroughly researched biological catalysts. However, the industrial application of PETase-mediated PET recycling is limited due to the low stability and poor reusability of the enzyme. Here we developed the whole-cell catalyst (WCC) in which functional PETase is attached to the outer membrane of Escherichia coli. Immunoassays are used to identify the surface-expressed PETase, and we demonstrated that the WCC degraded PET microparticles most efficiently at 30℃ and pH 9 without agitation. Furthermore, the WCC increased the PET-degrading activity in a concentration-dependent manner, surpassing the limited activity of soluble PETase above 100 nM. Finally, we demonstrated that the WCC could be recycled up to three times.

• Resources Recycling
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• v.31 no.1
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• pp.37-45
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• 2022

The development of the electrical, electronic, and telecommunication industries has increased the share of electricity in total energy consumption. With the enforcement of the Act on the Promotion of the Development, Use, and Diffusion of New and Renewable Energy in 2021, the mandatory supply ratio of new and renewable energy is expected to expand, and the amount of waste cables generated in the stage of replacing and discarding cables used in the industry is also expected to increase. The purpose of this study was to quantify the environmental burden of waste cable recycling through the life cycle assessment (LCA) method. The results showed that the higher the amount of glue contained in the waste cable, the greater was the amount of fine dust and greenhouse gases generated. In addition, by assigning weights to 10 environmental burden items, it was confirmed that the marine aquatic eco-toxicity potential (MAETP) and human toxicity potential (HTP) had the greatest environmental burden. The main causes were identified as heptane and ethanol, which were the glue contained in the waste cable and the cleaning solutions used to remove them. Therefore, it is necessary to refrain from using glue in the cable production process and reduce the environmental burden by reducing the use of waste cable cleaning solutions used in the recycling process or using alternative materials.

• Clean Technology
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• v.19 no.3
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• pp.257-263
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• 2013

The zinc phosphate-coated mica (ZP/mica) pigments were prepared using phosphoric acid, zinc nitrate and mica as starting materials, and used as anticorrosive pigments. The scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques were used to observe the morphology and crystal structure of prepared pigments. The prepared pigments were incorporated into an epoxy binder to prepare coating and the corrosion inhibition performance of the pigments was evaluated using electrochemical impedance spectroscopy (EIS). It was found that the anticorrosive performance of the ZP/mica pigment prepared at $70^{\circ}C$ was the better than that prepared at $20^{\circ}C$. The formation of ZnO, in addition to $Zn_3(PO_4)_2{\cdot}2H_2O$, was observed on ZP/mica pigment prepared at $70^{\circ}C$. The excellent anticorrosive performance of ZP/mica pigment could be ascribed to the synergistic effect with electrochemical anticorrosive mechanism from zinc compounds on mica and barrier anticorrosive mechanism from lamellar mica.

• Journal of Environmental Science International
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• v.23 no.10
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• pp.1703-1718
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• 2014

An eco-friendly integrated multi-trophic aquaculture (IMTA) farming technique was developed with the goal of resolving eutrophication by excess feed and feces as fish-farming by-products. A variety of seaweed species were tried to remove inorganic nutrients produced by fish farming. However, there have been few trials to use Sargassum fulvellum in an IMTA system, a species with a relatively wide distribution across regions with various habitat conditions, great nutrient removal efficiency and importance for human food source and industrial purposes. In this regard, our study tried to examine feasibility of using S. fulvellum in an IMTA system by analyzing growth characteristics of the species in an IMTA system comprising of rockfish (Sebastes shlegeli), sea cucumber (Stichopus japonocus) and the tried S. fulvellum (October 2011 - November 2012). We also monitored environment conditions around the system including current speed, water temperature and inorganic nutrient level as they may affect growth of S. fulvellum. S. fulvellum in the IMTA system, which were $15.72{\pm}5.67mm$ long at the start of the experiment in October 2011, grew to a maximum of $1093{\pm}271.13mm$ by May 2012. In September, seaweed growth was reduced to a minimum of $280{\pm}70.43mm$ in length. Then, S. fulvellum began to grow again reaching $325{\pm}196.19mm$ by November 2012. Wet weight of the seaweed was $4.01{\pm}1.89g$ at the start of the experiment and reached a maximum of $109.26{\pm}34.23g$ in May. The weight gradually declined to a low of $15.12{\pm}8.40g$ in September 2012. Weight began to increase once more, rising to $39.27{\pm}21.69g$ by November. During the experiment, the average velocity at the surface and the bottom was 6.5 cm/s and 3.4 cm/s, respectively. The water temperature ranged $5.0-23.5^{\circ}C$, which was considered suitable for growing S. fulvellum. Results of the study indicated no significant differences in inorganic nutrients between pre- and post-IMTA installation. It was thus concluded that S. fulvellum can be a suitable seaweed species to be used in an IMTA system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.294-301
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• 2017

In this study, we found the optimal manufacturing conditions of livestock manure sludge RDF with the oil-drying method. We performed oil evaporation, oil drying and pelletizing of the sludge to evaluate the value of the product (sludge RDF), and measured the performance of the product using calorimeter and PXRF equipment. Also, we conducted the calorie comparison test between sludge RDF manufactured in this study and wood RDF generally used in the field. Experimental results showed that 30g of the sludge treated by vegetable oil at $130^{\circ}C$ for 25 minutes were the optimal conditions to make the sludge RDF (considering the aspects of eco-friendly and mass production). The caloric value of the sludge RDF manufactured in this study was 5211kcal/kg which is higher than that of wood RDF used widely in the market. Finally, PXRF results showed sludge RDF contains no heavy metals with the exception of sulfur. Therefore, we recommend more study about the sulfur control process for future development of the industrial manufacturing process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5879-5884
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• 2013

With the rapid industrialization and economical development, the electricity demands of the industrial facilities and densely populated large cities are continuing to increase in Korea. The increase in the power consumption requires the extension of power facilities, but it is difficult to secure spaces for equipment installation in the limited space of urban areas. In addition, the 154 kV or 345 kV transmission systems in Korea has a short transmission distance, and are connected to one another in network structures that ensure the high reliability and stability of power supply. This structure reduces the impedance during the fault in power system, and increases the magnitude of in the short circuit fault current. The superconducting fault current limiter (SFCL) was devised to effectively address these existing problems. The SFCL is a new-concept eco-friendly protective device that ensures fast operation and recovery time for the fault current and does not need additional fault detection devices. Therefore, many studies are being conducted around the world. In this paper, based on the wiring method the initial fault current characteristics, current limiting characteristics, according to the incident angle and the change in inductance current limiting characteristics were analyzed in a multifaceted methods.

• Clean Technology
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• v.20 no.4
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• pp.439-448
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• 2014

The potential mitigation of greenhouse gas (GHG) is studied in the Pohang steel industrial complex (PHSIC). The total GHG emission in 2010 is estimated to be in the range from 4,174,000 to 4,574,000 $tCO_2-eq$ in PHSIC. To meet the target proposed by the government, it is needed to reduce 552,000 $tCO_2-eq$ at minium by 2020. To estimate the potential amount of GHG reduction, the technologies used in the voluntary carbon reduction projects are applied to 51 companies which are subject to GHG target management. From the viewpoint of technological availability and payback period, the fuel conversion and waste heat recovery have an advantage in the short term with a possibility to reduce 160,000 $tCO_2-eq$. In the mid term, the thermal technologies in steel and iron industry have the potential to cut 229,000 $tCO_2-eq$, while the electrical technologies have the potential of 125,000 $tCO_2-eq$ reduction. The gap between the target GHG mitigation and potential reduction using the short and mid term technologies is about 38,000 $tCO_2-eq$, which should be compensated by the fundamental process innovation and the implementation of the most cutting-edge technologies including renewable energy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.94-101
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• 2016

With increasing global concerns for environmental impacts, efforts have been made to encourage a modal shift from road freight to an eco-friendly transport system such as rail freight. In Korea, the government has set master plans for a green transport system but has not taken any substantial action to promote rail freight transport. In developing policies and actions to promote rail freight, quantitative studies on environmental impacts among transportation means are essential. This study examined the air pollutant emissions and greenhouse gas (GHG) emissions per unit freight transported by road and rail, respectively. To improve the accuracy, we analyzed emission data and freight transport mileage of rail freight considering diesel locomotives and electric locomotives separately. The results show that unit air pollutant emissions (except SO2) from road freight are about 7~15 times more than those from rail freight. In addition, the GHG emission unit of road freight is about 4 times higher than that of rail freight.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1161-1169
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• 2008

The removals of TCE and PCE vapor with or without a supply of toluene as a primary substrate were compared in a biofiltration process, and the variations of microbial communities associated with the removal were also investigated. As a result of investigations on the removals of TCE/PCE in a biofilter B within which TCE/PCE-acclimated sludge was attached on the surface of media without a supply of primary substrate, and those in another biofilter A where toluene-acclimated sludge was attached with a supply of toluene as a primary substrate, followings were found: (i) parts of microbes responsible to the decomposition of toluene vapor participate in the removal of chlorinated VOCs such as TCE and PCE, and (ii) effective biological removals of TCE and PCE vapor do not necessarily need cometabolism. Sequencing of 16S rDNA obtained from the band profile of DGGE (Denaturating Gradient Gel Electrophoresis), it was confirmed that: (i) uncultured alpha proteobacterium, uncultured Desulfitobacterium, uncultured Rhodobacteraceae bacterium, Cupriavidus necator, and Pseudomonas putida were found to be toluene-decomposing microbes, (ii) alpha proteobacterium HTCC396 is a TCE-removing microbe, (iii) Desulfitobacterium sp. is a PCE-decomposing microbe, and (iv) particularly, uncultured Desulfitobacterium sp. is probably a microbe decomposable not only toluene but also various chlorinated VOC vapor including TCE and PCE.