• Korean Journal of Environment and Ecology
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• v.36 no.2
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• pp.150-164
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• 2022

The objective of this study is to analyze the biodiversity changes and characteristics of the benthic macroinvertebrate community in the Nakdong River with eight weirs, which was constructed as one of the Four Major River Restoration Projects from May to October 2020. The study also includes the analysis of changes in the major groups of benthic macroinvertebrates for about ten years, from 2010 to 2020. The surveys collected 97 species of benthic macroinvertebrates belonging to 83 genera, 52 families, 18 orders, five classes, three phyla, and 128.1 individuals/m². Chironomidae sp. and Tubificidae spp., which are pollutant indicators, dominated throughout the sections. The community analysis result shows the average dominant index and the diversity index of 0.62±0.20 and 1.87±0.63, respectively, and indicated the most stability of the freshwater ecosystem in the upper stream of the Nakdong River. The survey showed dominance by Chironomidae sp. at the center of the Nakdong River weir and the most unstable community in Chilgok and Gangjeong Goryeong weirs. The results of the community stability analysis showed a high distribution of the characteristic group I with high resilience and resistance and small distribution of characteristic group III with low resistance and resilience, indicating a very unstable condition of communities in the Nakdong River weir section. Predators were relatively abundant among the functional feeding groups (FFGs), whereas shredders, gathering-collectors, and filtering-collectors were relatively lower. Among the habitat orientation groups (HOGs), burrowers and climbers were dominant, indicating a wide distribution of groups in ecosystems with low dissolved oxygen. An endangered species level II of Macromia daimoji was found in Sangju and Nakdan weirs. The analysis results for 10 years from 2010 showed that the number of species and populations increased immediately after the dam construction but plummeted in 2016 and are now stabilizing. Chironomidae spp. has been dominant in all sections over the past 10 years, and they are currently maintained at a rate of about 50%. The EPT groups have decreased significantly since 2011, and the Plecoptera and Trichoptera of the group have not yet been restored. The population of Tubificidae spp. showed an increase after construction was completed in 2012 and drastically increased in 2015 and 2020. The species of Cristaria plicata, designated as endangered species level I, has not been observed since 2011 in Hapcheon Changnyeong weir. Moreover, Macromia daimoji was rarely observed in seven weirs until 2015, and it has been confirmed that the current distribution habitat has decreased rapidly.

• Journal of Plant Biotechnology
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• v.35 no.3
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• pp.185-193
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• 2008

We evaluated the response to salt stress of two different ginseng lines, STG3134 and STG3159, which are sensitive and tolerant, respectively, to salt treatment. Plants were exposed to a 5 dS/m salt solution, and chlorophyll fluorescence was measured. STG3134 ginseng was more sensitive than STG3159 to salt stress. To characterize the cellular response to salt stress in the two different lines, changes in protein expression were investigated using a proteomic approach. Total protein was extracted from detached salt-treated leaves of STG3134 and STG3159 ginseng, and then separated by two-dimensional polyacrylamide gel electrophoresis(2-DE). Approximately 468 protein spots were detected by 2-DE and Coommassie brilliant blue staining. Twenty-two proteins were found to be reproducibly up- or down-regulated in response to salt stress. Among these proteins, twelve were identified using MALDI-TOF MS and ESI-Q-TOF and classified into several functional groups: photosynthesis-related proteins(oxygen-evolving enhancer proteins 1 and 2, rubisco and rubisco activase), detoxification proteins(polyphenol oxidase) and defense proteins($\beta$-1,3-glucanase, ribonuclease-like storage protein, and isoflavone reductase-like protein). The protein levels of ribonuclease-like storage protein, which was highly induced in STG3159 ginseng as compared to STG3134, correlated tightly with mRNA transcript levels, as assessed by reverse-transcription(RT)-PCR. Our results indicate that salinity induces changes in the expression levels of specific proteins in the leaves of ginseng plants. These changes may, in turn, playa role in plant adaptation to saline conditions.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.89-95
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• 2015

Carbon felts manufactured by (Co)CNF were subjected to heat treatment under different temperatures to use for the electrode of a redox-flow battery. BET and weight loss were tested to investigate the physical properties of the carbon felt according to the heat treatment conditions. SEM and XPS were also analyzed to characterize their surface area. In addition, electrical resistance, CV (cyclic voltammetry) and RFB charge on the electrode properties were examined in accordance with the heat treatment conditions with the discharge performance. The changes of physical properties on the carbon felt surface was confirmed via SEM and BET analysis, The most addition of oxygen functional groups on the carbon felt surface was obtained when one hour heat treatment at $550^{\circ}C$ and it was confirmed by XPS analysis. After resulting the CV tests, the active area of the electrode was the largest at $550^{\circ}C$ heat treatment. The heat treatment experiment of vanadium redox flow battery using the carbon felts were tested at $400^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$. As a result, the charge-discharge energy efficiency of the heat treatment electrode was 72.9% and 79.8%, at $400^{\circ}C$ and $500^{\circ}C$, respectively. The efficiency of the heat treatment electrode at $550^{\circ}C$ was the best as 79.8% at $550^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.1025-1032
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• 2009

This study investigated a possibility to develop an adsorption process for volatile organic compounds (VOCs) of the solvent emitted during dry cleaning. Pitch activated carbon fiber (ACF) was chosen as an adsorbent of VOCs, and an electric swing adsorption process was utilized for the reproduction of the adsorbent after the completion of VOCs adsorption. Effects of ACF types and several solvents such as trichloroethylene (TCE) and toluene were examined on breakthrough curves and amounts of adsorbed VOCs. ACF was pretreated under various conditions in order to enhance the amounts of the adsorbed VOCs. Temperatures and voltages were measured for the reproduction of the ACF after full adsorption. ACF having micropores exhibited high adsorption of TCE, and high surface area of ACF could increase the adsorption property of toluene. In general, ACF could adsorb 41~54% TCE of the adsorbent weight. The increase of inlet VOCs concentration significantly decreased the breakthrough time and slightly lowered the amounts of adsorbed VOCs. Thus, ACF could effectively adsorb VOCs in low concentration in the feed stream. ACF pretreated by heat under vacuum showed excellent toluene adsorption with controlling oxygen functional groups on the ACF surface, which revealed that vacant carbon site could be the adsorption point of toluene. Most adsorbed toluene was desorbed at $150^{\circ}C$.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.124-139
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• 2007

In order to obtain the maximum flame retardancy with the minimal deterioration of physical properties of PU flame-retardant coatings, chlorine and phosphorous functional groups were introduced into the pre-polymer of modified polyesters. In the first step, the tetramethylene bis(orthophosphate) (TBOP) and neohexanediol dichloroacetate (DCA-adduct) intermediates were synthesized. In the second step, 1,4-butanediol and adipic acid monomers were polymerized with the two kind of intermediates to obtain copolymer. The modified polyesters containing chlorine and phosphorous (ATBA-10C, -20C, and -30C) were synthesized by adjusting the contents of chlorine compound (dichloroacetic acid, 10, 20, 30 wt%) with fixed the content of phosphorous compound (2 wt%). The PU flame-retardant coatings (TTBAH -10C, -20C, and -30C) were prepared using the synthesized ATBAs and HDI-trimer as curing agent at room temperature. The physical properties of PU flame-retardant coatings with chlorine and phosphorous were inferior to those with phosphorous only and the properties were getting worse with increasing chlorine content. Flame retardancy was tested with three methods. With the vertical method, Complete combustion time of ATBAHs were $259^{\sim}347$ seconds, which means that the prepared coatings are good flame-retardant. With the $45^{\circ}$ Meckel burner method, char lengths of the three prepared coatings were less than 2.9 cm, which indicates that the prepared coatings are 1st grade flame retardancy. With the limiting oxygen index (LOI) method, the LOI values of the three prepared coatings were in the range of $30^{\sim}35%$, which proves good flame retardancy of the prepared coatings. From the results of flame retardancy tests of the specimens that contain the same amounts of flame retarding compounds, it was found that the coatings containing both phosphorous and chlorine show higher flame retardancy than the coatings containing phosphorous alone. This indicates that some synergy effect of flame retardancy exists between phosphorous and chlorine.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1407-1421
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• 2010

This study was carried out to elucidate the relation between water quality and structure of the aquatic ecosystem in the agriculture reservoir Otae-ji from January to December in 2009. The proportion of forest was 46.98%, which means that non-point sources are major contributor of water pollution in this area. The annual mean COD(Chemical Oxygen Demand) in Otae-ji was $3.6mgL^{-1}$, indicating, level II of environmental standards and the trophic state was mesotrophic. Although total phosporus concentration in the reservoir was high in August due to large inflow of nutrients from outside the reservoir during monsoon season, there was no break out of significant algal bloom in the summer. The seasonal succession of phytoplankton showed that the dinophyta dominated in the the spring, chlorophyta in the summer, chrysophyta and chlorophyta in the autumn and chrysophyta in the winter. In case of zooplankton, rotifers dominated in the most seasons, but cladoceran(Bosmina longirostris) dominated in June and copepod(Nauplii) in August. The macrophyte plants showed diverse species compositon consisted of 3 varieties, 24 species, 23 genera, 15 families and 14 orders. The macroinvertebrates also showed various FFG(Functional Feeding Groups) such as GC(Gathering-Collector), P(Predator), SH(Shedder), FC(Filter-Collector) and PP(Plant-Piercer). Ecosystem stability analysis using aquatic insects was classified as Group I, which has high resilience and resistance indices. A total of 14 species of fish was collected but exotic species such as Lepomis macrochirus and Micropterus salmoides were not found in Otae-ji. In conclusion, the preservation of healthy food wed in the reservoir ecosystem is closely related to water quality management as well as effective prevention of algal bloom by helping good material circulation in aquatic ecosystems.

• Journal of Life Science
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• v.27 no.6
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• pp.726-737
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• 2017

Carotenoids are isoprenoids with a long polyene chain containing 3 to 15 conjugated double bonds, which determines their absorption spectrum. They typically consist of a $C_{40}$ hydrocarbon backbone often modified by different oxygen-containing functional groups, to yield cyclic or acyclic xanthophylls. Much work has also been focused on the identification, production, and utilization of natural sources of carotenoid (plants, microorganisms and crustacean by-products) as an alternative to the synthetic pigment which currently covers most of the world markets. Nevertheless, only a few carotenoids (${\beta}-carotene$, lycopene, astaxanthin, canthaxanthin, and lutein) can be produced commercially by fermentation or isolation from the small number of abundant natural sources. The market and demand for carotenoids is anticipated to increase dramatically with the discovery that carotenoids exhibit significant anti-carcinogenic activities and play an important role in the prevention of chronic diseases. The increasing importance of carotenoids in the feed, nutraceutical food and pharmaceutical markets has renewed by efforts to find ways of producing additional carotenoid structures in useful quantities. Because microorganisms and plants synthesize hundreds of different complex chemical carotenoid structures and a number of carotenoid biosynthetic pathways have been elucidated on a molecular level, metabolic and genetic engineering of microorganisms can provide a means towards economic production of carotenoid structures that are otherwise inaccessible. The aim of this article is to review our current understanding of carotenoid formation, to explain the perceived benefits of carotenoid in the diet and review the efforts that have been made to increase carotenoid in certain microorganisms.

• Clean Technology
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• v.20 no.3
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• pp.218-225
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• 2014

Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. In this work, the gasification behavior of ash-free coal (AFC) was compared with that of the parent raw coal. In order to modify the gasification conditions, the raw coal gasified with fixed variables (water supply, space velocity, temperature, catalysts) in a fixed bed reactor. When catalysts are added by physical mixing method with coal, $K_2CO_3$ was the most effective additives for steam gasification of coal. However, the activity of ash-free coal (AFC) was much less reactive than raw coal due to high temperature extraction in a 1-methylnaphthalene under 30bar at $370^{\circ}C$ for 1 h, almost removed oxygen functional groups, and increased carbonization. The addition of $K_2CO_3$ in AFC achieved higher conversion rate at low temperature ($700^{\circ}C$). At that time, the molar ratio of gases ($H_2/CO$ and $CO_2/CO$) was increased because of water-gas shift reaction (WGSR) by addition of catalysts. This shows that catalytic steam gasification of AFCs is achievable for economic improvement of gasification process at mild temperature.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.395-405
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• 1994

The various functional groups, such as hydroxyl(-OH), carboxyl(-COOH) and quinonic oxygen(OC<) on the carbon black(abbreviated to CB) surface were activated with n-butyl lithium solution in n-hexane and then acrylate and methacrylate monomers were graft polymerized onto these activated anionic sites and CB-grafted polymers were obtained. To separate homopolymers from reaction mixture, non-solvent precipitation method or centrifugal separating method were applied. Subsequently, conversion, grafting ratio and efficiency were determined at various reaction temperatures and times. In case of acrylates, the grafting ratio showed 20~30% but methacrylates showed 150~200%. Also the anion polymerizations between CB and monomers were nearly reached to equilibrium state within one or two hours under each reaction temperatures but conversion and grafting ratio were increased a little with reaction temperature increase. In colloidal dispersion stability test, before heat-drying, the all CB-grafted polymers showed good dispersed stability in good solvents for acrylic and methacrylic homopolymers. Futhermore, CB-polymethacrylates were found to show excellent collidal properties for good solvents of methacrylic homopolymer even after heat-drying. Identification of the grafted polyacrylates and polymethacrylates onto the CB surface was performed by FT-IR spectroscopy. In addition, electric resistance values of CB-grafted polymers were measured by Four-probe method, and the increase of the grafting ratio showed the increase of the surface resistance.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.181-188
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• 2009

Pt catalyst was adsorbed on Carbon nanofiber (CNF) by modified polyol method after acid treatment of the carbon support with $HNO_3$ and $H_{2}SO_{4}$. As the time for acid treatment increases, more oxygen functional groups on carbon surface were produced which improve the loading amount and dispersion of Pt catalyst on carbon supports. In order to inspect the effect of CNF acid treatment time on electrochemical corrosion, constant potential of 1.4 V was applied to a single cell for 30 min and the amount of $CO_2$ emitted was monitored with on-line mass spectrometry. According to the results of our experiment, more $CO_2$ was produced with Pt/ oxidized-CNF catalyst in compared to that with unoxidized-CNF. Increasing acid treatment time also induces the more $CO_2$ emission. Besides, performance degradation after corrosion test expanded with severer carbon corrosion. From the observed results, it can be concluded that the acid treatment of CNF is beneficial to catalyst loading, but it also is a significant factor declining the fuel cell durability by accelerating electrochemical oxidation of carbon support.