• Membrane Journal
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• v.31 no.4
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• pp.253-261
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• 2021

Solutions to water pollution, global warming, and climate change have been currently discussed. Pressure retarded osmosis (PRO) using a difference in salt concentration between two fluids is proposed to meet the demand for clean water and produce eco-friendly energy. Although PRO has been researched continuously, it has not been commercialized yet due to limitations such as lack of technology and the high price of membranes. Meanwhile, the membrane is one of the most significant parts of the PRO engine and salinity gradient power (SGP) technology. Research continues to technologically develop graphene oxide membranes and nanocomposite membranes used in salinity gradient power generation. Studies on efficient membranes, solvents, and solutes are active to enable high energy efficiency of the osmotic heat engine even at low temperatures of waste. Studies have been conducted on reducing internal concentration polarization and increasing power density by using membranes with balanced permeability and selectivity. In this review, dealing with these studies, we discuss the types of PRO membranes, theoretical modeling of technologies through efficient membranes, and other technologies to develop the process efficiency.

• Clean Technology
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• v.27 no.1
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• pp.85-92
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• 2021

A solar water battery is a system that generates power using solar energy. It is a combination of photoelectrochemical cells and an energy storage system. It can simultaneously convert and store solar energy without additional external voltage. Solar water batteries consist of photoelectrodes, storage electrodes and counter electrodes, and their properties and combination are important for the performance and the efficiency of the system. In this study, we tried to find the effect that changing the components of solar water batteries has on its system. The effects of the counter electrode during discharge, the kinds of photoelectrode and storage electrode materials, and electrolytes on the solar energy conversion and storage capacitance were studied. The optimized composition (TiO2 : NaFe-PB : Pt foil) exhibited 72.393 mAh g-1 of discharge capacity after 15 h of photocharging. It indicates that the efficiency of solar energy conversion and storage is largely affected by the configuration of the system. Also, the addition of organic pollutants to the chamber of the photoelectrode improved the battery's photo-current and discharge capacity by efficient photoelectron-hole pair separation with simultaneous degradation of organic pollutants. Solar water batteries are a new eco-friendly solar energy conversion and storage system that does not require additional external voltages. It is also expected to be used for water treatment that utilizes solar energy.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.3
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• pp.137-146
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• 2022

Seed disinfection is a necessary process to decrease Bakanae disease in rice and is carried out at 30℃ to increase disinfection efficiency. However, the length of sprout after seed disinfection is not suitable for sowing, so additional processes such as seed soaking is needed. For this reason, this study was conducted to develop the efficient and effective seed disinfection method. When the seed disinfection finished after soaking seeds in cold water for 2 days, length of sprout was about 1.0 mm and sowing can be done without additional processes. In addition, the incidence of Bakanae disease was greatly reduced by 64% compared to conventional method. In order to find out why the newly developed method (disinfection after soaking) is more efficient than conventional method, soaked and not soaked seeds were stained using methylene blue staining. It was found that soaked seeds were more easily stained with about 50% of internal and external endosperm stained. Therefore, pesticide can be absorbed easily into internal endosperm of soaked seeds and efficiently destroy the spore of pathogen. As a results of this study, newly developed method will be useful as it can improve efficiency of agricultural work and also effectively decrease Bakanae disease compared to conventional method.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.891-899
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• 2024

The Fourth Industrial Revolution is centered on a personalized demand fulfillment economy and is all about transformation and flexible processing that can deliver what customers want in real time across space and time. This paper implements the construction and operation of a packaging platform that can instantly procure the required packaging products based on real-time orders and evaluates its performance. The components of customer satisfaction are flexible and dependent on the situation which requires efficient management of enterprise operational processes based on an e-SCM platform. An OMS optimized for these conditions plays an important role in maximizing and differentiating the efficiency of a company's operations and improving its cost advantage. OMS is a system of mass customization that provides efficient MOT(Moment of Truth) logistics services to meet the eco-friendly issues of many individual customers and achieve optimized logistics operation goals to enhance repurchase intentions and sustainable business. OMS precisely analyzes the collected data to support information and decision-making related to efficiency, productivity, cost and provide accurate reports. It uses data visualization tools to express data visually and suggests directions for improvement of the operational process through statistics and prediction analysis.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.503-515
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• 2014

A lot of existing wastewater treatment plants (WWTPs) are rebuilt or retrofitted for advanced wastewater treatment processes to cope with reinforced effluent criteria of nitrogen and phosphorous. Moreover, how to treat the wasted sludge from WWTPs has been also issued since the discharge of the wasted sludge into ocean is impossible from 2011 due to the London Convention 97 protocol. These trend changes of WWTPs get a motivation to assess environmental and economic impacts from the construction stage to the waste stage in WWTPs. Therefore, this study focuses on evaluation of environmental and economic impacts of the advanced wastewater treatment processes and waste sludge treatment process by using life cycle assessment. Four advanced wastewater treatment processes of Anaerobic/Anoxic/Oxic ($A_2O$), 5 stages-Bamard Denitrification Phosphate (Bardenpho), Virginia Initiative Plant (VIP), and Modified University of Cape Town (MUCT) are chosen to compare the conventional activated sludge (CAS) and three waste sludge treatment methods of land fill, incineration, and composting are used. To evaluate environmental and economic impacts of each advanced wastewater treatment processes, life cycle assessment (LCA) and life cycle cost (LCC) are conducted based on International organization for standardization (ISO) guidelines. The results clearly represent that the $A_2O$ process with composting shows 52% reduction in the environmental impact than the CAS process with landfill. On the other hand, the MUCT process with composting is able to save 62% of the life cycle cost comparing with the CAS process with landfill. This result suggested the qualitative and quantitative criteria for evaluating eco-environmental and economic technologies of advanced treatment processes and also sludge treatment method, where their main influence factors on environmental and economic impacts are analyzed, respectively. The proposed method could be useful for selecting the most efficient and eco-friendly wastewater treatment process and sludge treatment method when retrofitting the existing WWTPs to advanced treatments.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.71-85
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• 2018

A recent topic of interest within ecology is ecosystem services that are importantly connected with biodiversity. Biodiversity is a fundamental component of ecological studies and has been the subject of many studies worldwide. However, studies on the diversity and distribution of freshwater fish were not undertaken in earnest until 2000, and the number of internationally available studies is therefore still limited. In this study, we used data from "The Survey and Evaluation of Aquatic Ecosystem Health (hereafter SEAEH)" within the framework of which whole water systems on the Korean peninsula are annually monitored to investigate and determine the current status of the diversity and distribution of freshwater fish, as well as to elucidate major factors impacting freshwater fish. A total of 130 species from 28 families were identified at around 953 sites in the SEAEH investigation of 2014. The species Zacco platypus (relative abundance: 28.2%) and Z. koreanus (19.3%) were identified as the most abundant species on the Korean peninsula, and besides these 20 endangered species, 51 endemic species and 4 exotic species were also collected. Highest (96 species) and lowest (72 species) diversity were identified in the Han River Watershed and the Yeongsan/Seomjin River Watershed, respectively. The mean endemic rate was 32.7%, which is higher than the previous rate determined in 1995. The exotic species Micropterus salmoides, Lepomis macrochirus and Carassius cuvieri were found in the whole river system except north Yeongdong, whereas Oreochromis niloticus occurred only at three sites due to the cold water temperatures in winter. Totally, 28 species were found to be translocated to different water systems not connected with known original habitats, most translocations occurring in the Nakdong River and the Yeongdong region. Among the translocated species, Opsariichthys uncirostris amurensis, and Erythroculter erythropterus were dominantly distributed in the mid- to lower reaches of Nakdong River where they may be harmful to the native fish assemblages due to their strong predation. The construction of weirs in connection with the "4 River Project" generated changes in fish assemblages before, during and after the project, resulting in altered habitat condition. Especially, a decrease in the number of endemic species and an increase in the abundance of lentic species were seen. Human-induced global warming will allow exotic species requiring high water temperatures to adapt to the environmental conditions of the Korean peninsula, which may enhance the diversity of native fishes and create changes in distribution. For the establishment of realistic and efficient management and protection strategies for Korean freshwater fish, SEAEH, which produces fundamental and quantitative data for Korean streams, is an important and necessary tool.

• Korean Journal of Ecology and Environment
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• v.45 no.2
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• pp.218-231
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• 2012

The objectives of this study were to evaluate the physico-chemical water quality, trophic and tolerance guilds in the control ($C_o$) and impacted streams of the abandoned mine, along with the ecological health, using a multimetric health model and physical habitat conditions of Qualitative Habitat Evaluation Index (QHEI), during the period of three years, 2005~2007. Also, eco-toxicity ($EE_t$) enclosure tests were conducted to examine the toxic effects on the outflows from the mine wastewater, using the sentinel species of Rhynchocypris oxycephalus, and we compared the biological responses of the control ($C_o$) and treatment (T) to the effluents through a Necropybased Health Assessment Index ($N_b$-HAI). Tissue impact analysis of the spleen, kidney, gill, liver, eyes, and fins were conducted in the controlled enclosure experiments (10 individuals). According to the comparisons of the control ($C_o$) vs. the treatment (T) in physicochemical water quality, outflows from the abandoned mine resulted in low pH of 3.2, strong acid wastewater, high ionic concentrations, based on an electrical conductivity, and high total dissolved solid (TDS). Physical habitat assessments, based on Qualitative Habitat Evaluation Index (QHEI) did not show any statistical differences (p>0.05) in the sampling sites, whereas, the $M_m$-EH model values in a multimetric ecological health ($M_m$-EH) model of the Index of Biological Integrity (IBI), using fish assemblages, were 16~20 (fair condition) in the control and all zero (0, poor condition) in the impacted sites of mine wastewater. In addition, in enclosure eco-toxicity ($EE_t$) tests, the model values of $N_b$-HAI ranged between 0 and 3 in the controls during the three years, indicating an excellent~good condition (Ex~G), and were >100 (range: 100~137) in the impacted sites, which indicates a poor condition (P). Under the circumstances, organ tissues, such as the liver, kidney, and gills were largely impaired, so that efficient water quality managements are required in the outflow area of the abandoned mine watershed.

• Korean Journal of Microbiology
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• v.53 no.2
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• pp.83-96
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• 2017

A constructed sea stream in Yeongdo, Busan, Republic of Korea is mostly static due to the lifted stream bed and tidal characters, and receives domestic wastewater nearby, causing a consistent odor production and water quality degradation. Bioaugmentation of a microbial consortium was proposed as an effective and economical restoration technology to restore the polluted stream. The microbial consortium activated on site was augmented on a periodic basis (7~10 days) into the most polluted site (Site 2) which was chosen considering the pollution level and tidal movement. Physicochemical parameters of water qualities were monitored including pH, temperature, DO, ORP, SS, COD, T-N, and T-P. COD and microbial community analyses of the sediments were also performed. A significant reduction in SS, COD, T-N, and COD (sediment) at Site 2 occurred showing their removal rates 51%, 58% and 27% and 35%, respectively, in 13 months while T-P increased by 47%. In most of the test sites, population densities of sulfate reducing bacterial (SRB) groups (Desulfobacteraceae_uc_s, Desulfobacterales_uc_s, Desulfuromonadaceae_uc_s, Desulfuromonas_g1_uc, and Desulfobacter postgatei) and Anaerolinaeles was observed to generally decrease after the bioaugmentation while those of Gamma-proteobacteria (NOR5-6B_s and NOR5-6A_s), Bacteroidales_uc_s, and Flavobacteriales_uc_s appeared to generally increase. Aerobic microbial communities (Flavobacteriaceae_uc_s) were dominant in St. 4 that showed the highest level of DO and least level of COD. These microbial communities could be used as an indicator organism to monitor the restoration process. The alpha diversity indices (OTUs, Chao1, and Shannon) of microbial communities generally decreased after the augmentation. Fast uniFrac analysis of all the samples of different sites and dates showed that there was a similarity in the microbial community structures regardless of samples as the augmentation advanced in comparison with before- and early bioaugmentation event, indicating occurrence of changing of the indigenous microbial community structures. It was concluded that the bioaugmentation could improve the polluted water quality and simultaneously change the microbial community structures via their niche changes. This in situ remediation technology will contribute to an eco-friendly and economically cleaning up of polluted streams of brine water and freshwater.

• Korean Journal of Construction Engineering and Management
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• v.13 no.6
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• pp.3-12
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• 2012

The slowdown of private building industry resulted in growth of remodeling market as a way to improve energy performance. Remodeling is considered more cost-effective and eco-friendly approach for energy efficient building than new construction. Since 2008, Seoul has promoted Building Retrofit Project (BRP) preponderantly to attract energy-saving renovation by supporting building owners to switch building system into energy-saving system when they remodel their old buildings. According to 2012 press release, 254 Private sectors participated in this green building project and annually reduced 41000ton of greenhouse gas emission, 14000TOE, which also result in 7.5 billion won energy cost savings per year. The paper focuses on the building envelope remodeling as a way to improve energy efficiency. Different components of the building envelope such as wall insulation, window, and shading, were applied to the baseline model and the comparison was analyzed to come up with the ideal solution. This study only assesses the building envelope as to suggest the way to redesign the better energy performing building. Offering solution focusing on the architectural feature is essential because it will provide basic information and standard when remodeling a building for energy efficiency, especially, for the nonresidential buildings used as rental offices.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.855-862
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• 2017

Due to the weight reduction and miniaturization of satellites, there is a growing interest in low-cost launch vehicles, which are cheaper to launch than larger launch vehicles. One of the most cost-effective ways to reduce the cost of launch vehicles is the reuse of vehicles. Most companies that are developing low cost launch vehicles are also adopting a vehicles reuse approach. Along with this reuse purpose, the demand for environmentally friendly space launch vehicles has increased, so the choice of fuel used for low cost launch vehicles has also become very important. Methane and hydrogen-enriched compressed natural gas (HCNG), which makes more energy-efficient by adding hydrogen to methane, are considered to be the most suitable when considering other factors such as energy density among the fuels that are eco-friendly and capable of reusing the launch vehicles. This study investigated the trends of low-cost launch vehicle and rocket fuel in the world as a reference for setting up domestic space development after the development of Korea Space Launch Vehicle-II.