• Membrane and Water Treatment
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• v.10 no.3
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• pp.239-244
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• 2019

Plating wastewater containing various heavy metals can be produced by several industries. Specifically, we focused on the removal of copper (Cu2+) and nickel (Ni+) ions from the plating wastewater because all these ions are strictly regulated when discharged into watershed in Korea. The application of both nanofiltration (NF) and reverse osmosis (RO) technologies for the treatment of wastewater containing copper and nickel ions to reduce fresh water consumption and environmental degradation was investigated. In this work, the removal of copper (Cu2+) and nickel (Ni+) ions from synthetic water was studied on pilot scale remove by before using two commercial nanofiltration (NF) and reverse osmosis(RO) spiral-wound membrane modules (NE2521-90 and RE2521-FEN by Toray Chemical). The influence of main operating parameters such as feed concentration on the heavy metals rejection and permeate flux of both membranes, was investigated. Synthetic plating wastewater samples containing copper ($Cu^{2+}$) and nickel ($Ni^{2+}$) ions at various concentrations(1, 20, 100, 400 mg/L) were prepared and subjected to treatment by NF and RO in the pilot plant. The results showed that NF, RO process, with 98% and 99% removal for copper and nickel, respectively, could achieve high removal efficiency of the heavy metals.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.369-379
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• 2010

Zooplankton community structure and copepod production in Seomjin River estuary were investigated at 10 stations along the salinity gradients from May 2009 to February 2010. Total zooplankton taxa were identified to be 31 in the study area and seasonal average abundance of zooplankton was $4,151\;ind.{\cdot}m^{-3}$ during the study period. Zooplankton community was mainly composed of coastal species in dry season. However, brackish species dominated in upper or middle part of this estuary in flood season. This study showed that the growth rates of Acartia spp. and Paracalanus parvus s.l. measured from field experiments were regulated by the variations of Hater temperature and salinity; The annual copepod production estimated by dominant copepod species was $3.49\;g\;C{\cdot}m^{-2}yr^{-1}$, and the relatively high production value could be explained by the high phytoplankton standing stocks and the mass occurrence of coastal and brackish species with relation to various salinity gradients in Seomjin River estuary.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5B
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• pp.475-481
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• 2011

The TMDL standard flow as applying watershed management regime uses the average low flow of past 10 years. Moreover, the TMDL implementation assessment has been enforced through management of pollutant load satisfied objective water quality. Even though the present allocation and management through averaged low flow are still convenient, they are not enough to solve ultimate goals of watershed management to keep up recovery of water body. To maintain the same water quality concentration, the standard flow is required to consider total discharge in management plan which helps to keep healthy ecosystem. In view of this, it would be possible to approach reasonable assessment by reflecting variably changeable discharge from precipitation-streamflow relation and the TMDL standard establishment considering artificial regulated flow. Therefore, this study attempts to develop the TMDL method using Load Duration Curve (LDC) and Streamflow-Load Rating Curve (QLRC) considering total discharge and finds drawbacks with solutions as applying on Nakdong river TMDL unit watershed. Finally, this research evaluates possibility of application on pollutant load allocating and implementation assessment in Korea.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.1
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• pp.12-18
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• 2023

Objectives: Personal protective equipment (PPE) is an essential means for protecting workers against hazardous agents or risks that threaten their safety and health. Governmental organizations related to safety and health in the workplace regulate the PPE rules to protect workers and to minimize damage from hazardous agents. This study discussed current PPE rules overseen by the Korea Ministry of Environment and explores future perspectives on the matter. Methods: This study was based on a review of PPE regulations with which every stakeholder should comply in the workplace. Both South Korean regulations enforced by the Ministry of Employment and Labor and the Ministry of Environment and cases from other countries were reviewed. Results: Regulations related to the PPE required for handling chemical substances in the workplace are enforced by the Occupational Safety and Health Act, Enforcement Decree, Enforcement Rules, and Notification of Protective Equipment Certification under the Ministry of Employment and Labor. The Ministry of Environment also regulates the PPE standards for 97 substances requiring preparation for accidents and adjustment of work conditions, but a recent amendment (partially amended on September 30, 2022) loosened some unreasonable or excessive provisions. It requires workers simply to carry or otherwise keep PPE handy instead of wearing it for some tasks in which hazardous chemicals are not handled directly. Conclusions: It is important to regularly review provisions that need to be improved or supplemented to help all stakeholders. Considerations should be also made to build a reasonable regulatory system that can induce more mature safety management in each workplace.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.551-560
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• 2013

Environmental factors and epilithic diatom communities in the lower streams near the harbor region of South Korean peninsula were examined during no monsoon period in May 2013. The sampling of water and epilithic diatoms was conducted at both streams, 19 regulated streams (RS) that there are one or several dams constructed in the river system, and 19 un-regulated streams (US) that there are no dams within the river. A cluster analysis based on the number of species and abundance of epilithic diatoms through the stations, divided into three groups such as groups I (mainly US), II (mixed with US and RS) and III (mainly RS), respectively. Group I showed that water quality is good and high diversity of diatom, while Group II and III was water quality is relatively poor, but not differed in biomass of diatom from Group I. In addition, Group II that had high conductivity, nitrogen and phosphorus, was the lowest in diatom diversity among them. Dominant species were Nitzschia palea (17%) and Navicula seminuloides (11%) in Group I, Nitzschia inconspicua (19%) and Navicula perminuta (9%) in Group II, and Nitzschia inconspicua (15%) and Nitzschia palea (14%) in Group III, respectively. These taxa were widely distributed in brackish water, and not closely related with specific water quality, like eutrophic water. However, the groups II and III belonged to RS, had not only little biomass, but bad water quality such as high concentrations of nutrient and chlorophyll-a. Therefore, to determine the effect of dam construction on the lower water ecosystem, the planktonic algae, which can occur algal bloom in the estuary, also was considered to be a parallel investigation.

• Economic and Environmental Geology
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• v.41 no.6
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• pp.673-683
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• 2008

As-rich alluvial groundwaters occurring in the agricultural area of Mankyeong River watershed were geochemically studied. 15 out of 29 investigated wells (52%) showed As levels exceeding the WHO drinking water standard ($10{\mu}g/L$). Their chemistry is characterized by low Eh levels, low $NO_3$ and $SO_4$ concentrations, and high pH, alkalinity, Fe, $NH_4$, and $PO_4$ levels. This suggests that arsenic is enriched by the reductive dissolution of As-bearing Fe-/Mn-(hydro)oxides, the commonest process in Bangladesh and West Bengal of India, of which groundwaters are severely contaminated by As. It was also revealed that As concentrations in the area are strongly regulated by the presence of agrochemicals such as $NO_3$ and $SO_4$.

• Journal of Microbiology and Biotechnology
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• v.19 no.5
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• pp.431-438
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• 2009

The alkaline serine protease asp, which was shown to be a virulence factor of Vibrio alginolyticus as a purified protein, was cloned from V. alginolyticus EPGS, a strain recently isolated from moribund Epinephelus coioides in an outbreak of vibriosis in a mariculture farm of Shenzhen. The asp null mutant was constructed by homologous recombination with suicide plasmid pNQ705-1. Compared with the wild-type strain, the asp null mutant exhibited a significant decrease of total extracellular protease activity, and caused a IS-fold decrease in virulence of V. alginolyticus. In our previous study, the luxO and $luxR_{val}$ genes from V. alginolyticus MVP01 were cloned and identified, and the luxO-$luxR_{val}$ regulatory couple was shown to regulate various genes expression, suggesting that it played a central role in the quorum sensing system of V. alginolyticus. In this study, the regulation of the asp gene was analyzed by using RT-PCR and quantitative real-time PCR methods; we proved that its transcription was greatly induced at the late stage of growth and was regulated by a luxO-$luxR_{val}$ regulatory system.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1107-1108
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• 2006

As expanding municipal and industrial areas since started the economic development plan in earnest in 1970's, the water resource, mainly river surface water has been seriously polluted. Nevertheless, being upgraded in their treatment technologies for the drinking water, the safety has been issued one of crucially social problem in Korea. The water authorities has tried to improve the quality such as amending the drinking water quality standard to be monitored; hazardous chemicals and microorganis have been added and now 55 items, before 47 items, since in 2002. The Water Authorities of Seoul, the capital city of Korea, planned to assess the safty of drinking water quality after amended the standard. This study was conducted to assess the risk due to polluted chemicals including 21 heavy metals, VOCs, pesticides, PAHs, DBPs and organic chemicals among the regulated items. The risk assessment were undertaken hazard identification, exposure assessment, dose-response assessment and risk characterization. For the exposoure assessment, tap water, bottled water and purified water were sampled and analyzed in February, 2004. Risk characterization of detected chemicals was categorized into carcinogenecity and noncarcinogenecity, and estimated the excess of carcinogens and compapared with the reference dose (RfD) of noncarcinogenns. The excess risk of carcinogens from samples were considered comparatively in the acceptable levels; $10^{-6}$ for cancer risk and hazard quotient (HQ) 1.0 for noncancer risk. The deteced levels were estimated in $10^{-5}{\sim}10^{-6}$ of cancer risk and below 1.0 of HQ of noncancer risk. While three kinds of water were determined within the acceptal levels, DBPs were detected in tap water and purified were and some undesireable chemicals such as more fluoride detected rather than the quality stanadard. For the drinking water safety, it shoud be continuously monitored, assessed and managed as well risk communiction between the authoritis and public.

• Architectural research
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• v.21 no.4
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• pp.91-98
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• 2019

In modern times, numerous cities are competing to create the unique skyline adjacent to the water. Tall buildings located across the river have a great contribution to the skyline of a riverfront city and can be a precious asset for the city. Moreover, in several cities, tall buildings and their impact on the urban skyline are a matter that should be considered and regulated in urban design. Therefore, as a prominent element in a larger visual setting of the city, tall buildings should improve the visual quality of the skyline rather than diminish that quality. This research attempts to provide an objective method to analyze the visual quality of the skyline made by a group of tall buildings through their feature of heights and spatial arrangement from riverfront views. The analysis is determined by the design variables of building heights variation, heights transition, density, and spacing of a group of tall buildings. A comparative case study of tall buildings in Yeouido and Lujiazui was conducted to prove the effectiveness of the analysis. The proposed method can be used in a simple way in the quantitative approach to quantify the visual quality of the skyline. In conclusion, Yeuido's skyline is not quite interesting from the riverfront view in terms of height variation and continuity of the skyline view because they are dispersed. Conversely, Lujiazui's skyline from the riverfront vantage points has a good quality in all aspects of the feature of height and spatial arrangements of tall buildings cluster. These factors can be used for the urban designer on how proposed tall buildings within the cluster should appropriately respond to adding image on the skyline.

• Journal of Korea Water Resources Association
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• v.49 no.7
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• pp.599-606
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• 2016

The objective of this study is to estimate the unregulated flood frequency from Chungju dam to Yangpyung gauging station for the region affected by dams based on the peak discharges simulated by storage function routing model. From the flood frequency analyses, the quantiles for the unregulated flood frequency at 6 sites have similar pattern to each other, and their averaged quantile almost matched to the result from the regional flood frequency analysis. The quantile and annual mean discharge for the unregulated flood frequency for the downstream of Chungju dam show the similar behaviour to those for the upstream area. While the quantile and the annual mean discharge for the regulated flood frequency are significantly different from those for the unregulated flood frequency. In particular, the qunatile shows severe difference as the return period increases, and the annual mean discharge has a tendency to approach to the natural flood as the distance from dam increases.