• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.104-110
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• 2010

Eutrophication is a well-known phenomenon in lentic habitats, however it is receiving increasing attention in shallow streams of Korea due to the increase of periphyton to a nuisance level. In this study temporal and spatial variation in periphyton standing crop and nutrient concentrations were surveyed in the upper reach of the Han River (the Inbuk Stream) that used to be a pristine rural stream until 1980s. Chlorophyll-a concentration per unit surface area of bottom substrate was examined monthly for one year period at nine sites along the Inbuk Stream together with environmental factors such as phosphorus, nitrogen, and water velocity. The standing crop of periphytic algae ranged from $4{\sim}242mgChl.a/m^2$ with a median of $55mgChl.a/m^2$, often exceeding the nuisance level criterion. Along the stream periphyton increased significantly from $39{\pm}48mgChl.a/m^2$ to $94{\pm}49mgChl.a/m^2$ after merging of a tributary in an intensive agricultural basin with high phosphorus concentrations. Seasonally periphyton biomass was highest in autumn (median $171{\pm}76mgChl.a/m^2$) from October through December when water flow velocity was low (median $0.4{\pm}0.3m/s$), while it was higher in flood season (median $1.2{\pm}0.4m/s$) and freezing season (median $0.2{\pm}0.3m/s$) was lower. The result shows that this rural stream often shows characteristics of eutrophication according to periphyton standing crop and it may be regulated by phosphorus and water velocity.

• Plant Biotechnology Reports
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• v.5 no.4
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• pp.323-329
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• 2011

MuSI, a gene that corresponds to a domain that contains the rubber elongation factor (REF), is highly homologous to many stress-related proteins in plants. Since MuSI is up-regulated in the roots of plants treated with cadmium or copper, the involvement of MuSI in cadmium tolerance was investigated in this study. Escherichia coli cells overexpressing MuSI were more resistant to Cd than wild-type cells transfected with vector alone. MuSI transgenic plants were also more resistant to Cd. MuSI transgenic tobacco plants absorbed less Cd than wild-type plants. Cd translocation from roots to shoots was reduced in the transgenic plants, thereby avoiding Cd toxicity. The number of short trichomes in the leaves of wild-type tobacco plants was increased by Cd treatment, while this was unchanged in MuSI transgenic tobacco. These results suggest that MuSI transgenic tobacco plants have enhanced tolerance to Cd via reduced Cd uptake and/or increased Cd immobilization in the roots, resulting in less Cd translocation to the shoots.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.1
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• pp.60-69
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• 2023

Objectives: Business operators handling hazardous chemicals regulated under the Chemical Substances Control Act (CSCA) must receive permits to operate their business from the Ministry of Environment. This study analyzed the status of recent legal violation in chemical handling workplaces in Ulsan where a large volume of chemicals is handled for industrial use. Methods: A total of 557 corporations have been granted legal status as business operators in Ulsan. For all business operators, legal violations in regard to the CSCA that were discovered by the environmental office in the last five years (2018~2022) were thoroughly analyzed. Results: A total of 225 violations of the CSCA have been discovered at 165 corporations, with the violation rate accounting for approximately 27% of all business operators. In particular, 22% of the 165 violators (36 corporations) were discovered to have violated twice or more, and some business operators (6%) even violated in consecutive years. Non-compliance of facility inspection was the most frequent violation (45 cases, 20.1%), followed by non-reporting of important changes in the permitted matters (23 cases, 10.3%), non-completion of legal safety education (19 cases, 8.5%), failure to secure permission for modification in the permitted matters (18 cases, 8.0%), and failure to submit chemical transport plans (16 cases, 7.1%). Conclusions: Most of the violations could have been prevented if the field personnel had paid sufficient attention. Thus, it is fundamentally necessary to create an environment for spontaneous safety management for themselves and to strengthen individual capabilities.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.225-237
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• 1990

Various chemical constituents were measured from April to August 1988 at the down-ward 20 stations of Keum River, which is located in the Midwest of Korea, to understand the characteristics of water quality with respect to spatio-temporal variations of each constituent. The 24-hrs continuous measurements with 2-hrs interval were made simultaneously at station 2 near the estuary weir and station 9(Ganggyeong) of 35 km upstream from the weir in April. By the results observed for one day in April at station 2, salinity has a range of $7.88\~22.14\%_{\circ}$ and its temporal variability is identical to the pattern of tidal cycle in the neigh-bouring Kunsan Harbor. However, turbidity shows relatively high values only at an interval of 4~5 hours after the lowest salinity time, though hourly fluctuation of pH is very small. Silicate and dissolved inorganic nitrogen have inversively linear correlationships with salinity, implying the concentration of the two nutrients strongly regulated by estuarine mixing of sea and river waters. In contrast, phosphate sustains roughly a constant level over a wide salinity range and distinctly lower values than those corresponding to nitrate in the oceans. Such distributions of phosphate have been observed in some estuaries, and interpreted as driven by removal of dissolved phosphate into bottom sediments and the bufforing of phosphate by particulate matter. COD values at station 2 are relatively high in day-time(particularly afternoon) and in high-salinity periods. At station 9, saltwater intrusion was never found but water level changed to the extent of 2.5 m for one day. Although each parameter at this station exhibits very slight variations in their abundance for 24 hours compared with station 2, the contents of COD, silicate and ammonia are significantly higher than at station 2. Concentration of suspended matter is relatively high in the brackish water region up to $\~20$ km above the river mouth, probably due to strong tidal stirring of the bottom de-posits. Also, relatively high pH, COD and $O_2$ saturation at the upward stations of $40\~50$ km from the weir are presumably attributable to active photosynthesis of plants in the region. In general, COD and nutrients except phosphate are higher values at the upper stations than in the estuary zone, and show the highest abundances in July nearly at all stations. Finally, in the estuarine region tidal mixing of sea-river waters seems to be an important factor controlling the distributions of turbidity, COD, silicate and nitrate as well as salinity. However, water quality in the upward fresh-water zone is remarkably variable according to months or seasons.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.2
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• pp.61-71
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• 2014

A river fishway is a hydraulic structure enabling fish to overcome stream obstructions such as dams and weirs. The main aim of this paper is to investigate the collectibility of upstream-migrating fishes and hydraulic problems in pool-and-weir type fishway which has been established for upstream-migration at Namgang weir in the downstream of Namgang dam, and to grope for improvement measures which pool-and-weir type fishway can be switched to pool-and-partial weir type fishway through hydraulic field experiment. Exsisting fishway had problems which upstream-migrating fishes can not take a rest due to the seiche and vortex phenomena in pools and migrate to upstream because of height difference in entrance pool. In order to prevent hydraulically the seiche and vortex phenomena and establish rest area for fishes in each pool, we carried out hydraulic field experiments. In the fishway, it was to improve pool-and-weir into pool-and-partil weir, to decrease the height difference in entrance pool, and to reduce oriffice velocity of each pool. Also, we investigated fishes collectibility of after improving fishway for 6 days in September 2013. To resolve chronic problems(seiche-vortex phenomena and rest area for fishes), as weirs were remodeled into partial weir only which central part of weirs was part of non-overflow weir, we confirmed results that pool-and-weir type fishway could be switched to efficient pool-and-partial weir type fishway with relatively simple construction and low cost. Type-B which has the closed oriffices and the parts of non-overflow has the ideal conditions, but this conditions are limited to fishway of Namgang weir used in this study. Representative Ice-habor type fishway is pool-and-partial weir type fishway which has together parts of overflow and oriffices, and has excellent ability of upstream-migration. To switch from pool-and-weir type fishway to pool-and-partial weir type fishway, the size of oriffice has to be regulated by the discharge of fishway and the dimension on parts of non-overflow and overflow in weirs. Entrance pool is important facility which upstream-migrating fishes have to not only be collect but also charge with energy. In this study, entrance-pool is temporary and roughly-built, but fishes gather together more than the case of no entrance-pool. In the case of fishway which was protruded to downstream, as entrance of fishway turns toward or parallels to weir, the collectibility of fishway was excellent by attraction water.

• Journal of Korean Port Research
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• v.6 no.1
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• pp.93-110
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• 1992

The most change in this century is supposed to be declination of ideology, and block of world economy. Addition to down full of cold war atmosphere around Northeast Asia, not only economic and social mood in this region is dramatically changed, but also it gave birth to the block of Northeast economy that accerlated new hub of world economy. According to dramatic change of economic surroundings the dynamic potential of growth in this region will be guided to enlarge inter-regional trade and increase volume of trade, thus suggests to grow steadily transportation. cargos in this region will have to arrange the system of delivery and inner transportation, accessary facilities, inter-regional harbors if North America and EC has connected easily. As have accerlated GATT and UR represented multilateralism and regionalism, it has regulated to increase trades of region due to relief of the trade barrier through specific areas has agreed with separately. The flow of regionalism of world economy has appeared to realize EC and NAFTA centered U.S.A, and also has presented to free trade region or one-size market agreement in Asia as APEC, EAEG in Malaysia, and etc. In defense to this block and internationalism of world economy, Pusan has to come forward to the hub of Northeast others has proposed a project to dominate the Northeast, Economy Association Agreement as Far East comprehensive development project in USSR, Hunchun development project in NK, and East Sea development project in PRC, Niigate regional development in Japan, Duman River development project in NK, and East Sea development project in Korea. As this exercise has proceed, Pusan also have arranged development strategy definitely and prepared provisions systematically. Engaging to participate center of delivery system is meant to be completed complex functions, namely the transfer storage processing & assembly function of international commodity. Pusan has ability to be terminal point of TSR. it had been connected to EC as the biggest economy block and TKR as complex transportation root to Far East, it would be the center of inground and seabase delivery terminal to Rotterdom as the biggest container pier and major piers to North-East and South East Asia. In order to provide a Role of 21 century's internationalization, Pusan has appealed to participate in management information research and development connected to Pohang-Ulsan-Changwon-Masan, and has utilized efficiently the resources such as man, material, money and information.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.9-19
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• 2001

contrasting monsoon between 1993 and 1994 produced an interannual difference in hydrology. Theoretical water residence time (TWRT) in monsoon 1993 averaged 27 d, which was>3 months shorter compared to the TWRT in monsoon 1994. A dominant physical process influencing thermal stratification, water movement, and mixing regime was an interflow current in 1993. During summer 1993, river water plunged to mid-lake (location 27 km) and passed through the 10${\sim}$20m stratum of the reservoir, resulting in an isolation of epilimnetic lake water from advected river water. The interflow disrupted thermal stratification and produced a meta-hypolimnetic warming of >4$^{\circ}C$ downlake, thereby increased a mixing depth (>13 m). In contrast, during monsoon 1994 density currents were not observed and strong thermal stratification occurred in the entire reservoir, resulting in > 2 fold greater thermal resistance (8.2${\times}10^{5}$ erg)compared to 1993 (4.0${\times}10^{5}$ erg). This reservoir was identified as a typical warm monomictic reservoir which showed one mixis during early winter. The timing of overturn, however, differed between the two years as a result of distinct contrast in TWRT and thermal regime; overturn in 1993 occured about one month earlier relative to that in 1994. Hypolimnetic warming was predictable in this system; the variation in discharge accounted (Y = 4.35-0.06X+0.10X$^{2}$, p<0.0001)for 98% of the interannual variation in hypolimnetic temperature. Overall data suggest that thermal stability, the timing of fall overturn, and water residence time in this system are primarily regulated by the intensity of monsoon.

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1284-1289
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• 2007

The Biological Activated Carbon (BAC) process in the water treatments represents a kind of biofiltration process which capabilities of bacteria to remove organic matters are maximized. It enables to eliminate organic matters and effectively reduce microbial regrowth potentials. As attached bacteria employ natural organic matter as a substrate, they are significantly dependent on indigenous microorganisms. In this study, characteristics of bacterial community by culturable and unculturable Methods have been conducted in a pilot plant using SAC in water treatment process at the downstream of the Nakdong River. Based on the results, HPC and bacterial- production for coal-based activated carbon material were $1.20{\sim}56.2{\times}l0^7$ cfu/g and $1.2{\sim}3.7\;mgC/m^{3}h$, respectively, in the SAC process. The highest level of attached bacteria biomass and organic carbon removal efficiency was found in the coal-based activated carbon. The genera Pseudomonas, Flavobacterium, Alcaligenes, Acilzetobacter, and Spingomonas were identified for each activated carbon material. Pseudomonas vesicularis was the dominant species in the coconut- and coal-based materials, where as Pseudomonas cepacia was the dominant species in the wood-based material. The Scanning Electron Microscope (SEM) observation of the activated carbon surface also found the widespread distribution of rod form and coccus. The community of attached bacteria was investigated by performing Fluorescent in situ hybridization (FISH) analysis. a group was dominant in coal, wood and coccunt-based materials, ${\alpha},\;{\beta}\;and\;{\gamma}$ group ranged from 27.0 ${\sim}$ 43.0%, 7.1 ${\sim}$ 22.0%, 11.3 ${\sim}$ 28.6%, respectively. These results suggest that a group bacterial community appears to be regulated removal efficiency of organic material in water treatment process.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.260-269
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• 2009

Hwabuk Dam has been under construction to reduce flood damage in Nakdong River watershed and to supply stable water for middle area of Gyeongbuk Province. Therefore, fish investigation in up and downstream of the dam was conducted from 2004 to 2008 in order to determine any negative effect on fish community due to dam construction and to use as fundamental data for conserving species diversity and maintaining stream health. According to data analysis on water quality, temperature, dissolved oxygen, pH, suspended solids, and total E-coli had seasonal variation, but they did not significantly differ in sites. However, biological and chemical oxygen demand, chlorophyll-a, nitrogen, and phosphorus representing organic matter and nutrient concentration were higher in upper site and decreased to lower site so that they differed by site. Concentration of arsenic among the heavy metals was less than 0.05 mg $L^{-1}$, which is regulated for protection of human health in water quality standard, except for 0.092 mg $L^{-1}$ in June 2005. During the study period, the total number of fish caught from the 6 sites was 10,263 representing 7 families 19 species. Among them, dominant and subdominant species were Korean chub (Zacco koreanus, 62.5%) and Chinese minnow (Rhynchocypris oxycephalus, 10.6%) which inhabit mostly in mid and upper streams, Korea. Among the 19 species, Korean endemic species were 9 species (47.4%) including Korean slender gudgeon (Squalidus gracilis majimae), Korean dark sleeper (Odontobutis platycephala), and Korean shiner (Coreoleuciscus splendidus). There was several individuals of the $1^{st}$-class endangered species, Naktong nose loach (Koreocobitis nahtongensis), caught in 2005${\sim}$2007, and no introduced species of fish was found in entire sampling period. According to result of community analysis, dominance index decreased toward lower site, but diversity and richness indices increased toward lower site. The equation of length-weight relationship on the dominant species was TW=0.000003$(TL)^{3.2603}$. The parameter b in the equation was greater than 3.0 indicating good nutritional condition in the populations. Compared to populations of Korean chub in other streams, the population in Hwabuk Dam watershed had higher mean of condition factor by size indicating better growth rate. With fish fauna and multi-metric health assessment model in each sampling attempt, index of biotic integrity (IBI) was evaluated and it resulted mostly in good (26${\sim}$35) and excellent (36${\sim}$40) condition in all sites, and the mean of IBI was the highest in site 5. The results indicate that it is very important to study not only environmental impact assessment with fish composition but also stream health assessment in order to conserve healthy aquatic ecosystem.