• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.842-846
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• 2013

In 2012, the Korean Ministry of Environment (MOE) added 3 new water quality standards for the protection of human health; specifically, regarding 1,4-dioxane, formaldehyde, and hexachlorobenzene. In this study, we assimilated the water quality standards of these 3 substances from other countries, with respect to surface water quality standards for human health protection and drinking water standards. We subsequently investigated how these standard values were derived. 1,4-Dioxane is managed as an environmental standard for human health in Japan, and as a drinking water quality standard in WHO, New Zealand, and Japan with respect to both carcinogenic and non-carcinogenic effects. In New York, the oncogenic effects of formaldehyde in drinking water intake is considered, whereas WHO, Australia, New Zealand, and Japan also assess the non-carcinogenic effects of formaldehyde when setting their standards. USEPA and New York have a water quality standard for human health protection with respect to hexachlorobenzene based on carcinogenic effects. This study focuses on deriving water quality standards for the 3 new substances, or obtaining baseline information to revise the values of existing substances in the future.

• Journal of Information Processing Systems
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• v.16 no.4
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• pp.784-794
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• 2020

In order to effectively evaluate the urban water security, the study investigates a novel system to assess factors that impact urban water security and builds an urban water poverty evaluation index system. Based on the contribution rates of Resource, Access, Capacity, Use, and Environment, the study adopts the Water Poverty Index (WPI) model to evaluate the water poverty levels of 14 cities in Gansu during 2011-2018 and uses the least variance method to evaluate water poverty space drive types. The case study results show that the water poverty space drive types of 14 cites fall into four categories. The first category is the dual factor dominant type driven by environment and resources, which includes Lanzhou, Qingyang, Jiuquan, and Jiayuguan. The second category is the three-factor dominant type driven by Access, Use, and Capability, which includes Longnan, Linxia, and Gannan. The third category is the four-factor dominant type driven by Resource, Access, Capability, and Environment, which includes Jinchang, Pingliang, Wuwei, Baiyin, and Zhangye. The fourth category is the five-factor dominant type, which includes Tianshui and Dingxi. The driven types impacting the urban water security factors reflected by the WPI and its model are clear and accurate. The divisions of the urban water security level supply a reliable theoretical and numerical basis for an urban water security early warning mechanism.

• Journal of Environmental Science International
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• v.31 no.4
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• pp.341-356
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• 2022

Electrical Conductivity (EC) or Total Dissolved Solids (TDS) has been often used to evaluate the water quality in some water education program for children and youth. This study attempted to find out whether EC (or TDS) can be used as a water pollution criteria in water education program. To clarify it, we used the water analysis data of July 2019 and January 2020 from Water Environment Information System. Data from 332 points in Han-river were used to investigate correlation between the parameters, such as BOD, COD, TN, TP vs EC. Correlation(r) for all data of BOD vs. EC was 0.347 for July 2019 and 0.483 for January 2020. No correlation was observed for BOD Ia and BOD Ib for July 2019 (r=-0.041, -0.030, respectively) and BOD Ia for January 2020 (r=0.041). Better correlation for all data of COD vs. EC was obtained (r=0.543 for July 2019 and r=0.610 for January 2020). However, no correlation was observed for COD Ia for January 2020. High vlaue of EC or TDS does not always mean water pollution, especially for clean water environment. Thus, EC (or TDS) alone can not be used as a water pollution criteria.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.580-588
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• 2019

The flow of the middle and downstream of the Yeongsan River is stagnant by two weirs of Seungchon and Juksan and the estuary dam and maintained in freshwater. In this study, the Environmental Fluid Dynamics Code-National Institute of Environment Research(EFDC-NIER) model was applied to the Yeongsan River to simulate water flow, temperature, and salinity stratification. The EFDC-NIER model is an improved model which can simulate multi-functional weirs operation, multiple algal species, and the vertical movement mechanism of algal based on the EFDC model. The simulation results for the water level, water temperature, velocity, and salinity reproduced the observed values well. The mean absolute error(MAE) of the model calibration in the annual variations of the water level was 0.1-0.3 m, water temperature was 0.8-1.7 ℃, velocity was 4.5-7.1 cm/sec, and salinity was 1.5 psu, respectively. In the case of scenario simulation for the full opening of the estuary dam, the water level of the estuary dam was directly impacted by the tide so it was predicted to rise - 1.35 m to 0.2 m on average sea level. The velocity was also predicted to increase from 2.7 cm/sec to 50.8 cm/sec, and the flow rate to increase from 53 ㎥/sec to 5,322 ㎥/sec.

• Hwankyungkyoyuk
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• v.21 no.4
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• pp.25-39
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• 2008

The purpose of this study is to realize the teaching material, which develops the Model of Watershed Water Environment Education(EE) Textbook, by seeking for a method of the Inquiry with the Perspective of EE and by questing for the contents of watershed water environment necessary for Water EE with the Perspective of EE. First, the value of watershed EE was reilluminated through the literature analysis on the watershed. And 'Inquiry with the Perspective of EE' methodology was newly presented that quests for the contents necessary and proper for EE from the viewpoint of EE. Also, with suggesting it as concept and methodology of 'Inquiry with the Perspective of Watershed EE' by considering the value of EE in Water EE, it presented the content approach direction in the inquiry and the contents of the specific inquiry. Second, through the Inquiry with the Perspective of EE into water environment of the watershed Musim cheon (stream), which is a case region, it allowed the watershed water environment to be able to be synthetically understood. As for a sphere of the inquiry, 5 spheres were sought by taking into account a relation to a human being, as well as the water environment itself of the watershed Musim cheon (stream). Third, Based on the contents of the Inquiry with the Perspective of EE into the watershed Mlisim cheon (stream), 'the Model of Watershed Water EE Textbook' for middle-school students was developed. This model of textbook was selected largely four parts, and was organized with 10 learning objectives and 11 activities.

• Membrane and Water Treatment
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• v.8 no.5
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• pp.449-462
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• 2017

Direct treatment of municipal wastewater by forward osmosis (FO) process was evaluated in terms of water flux decline, reverse salt diffusion, pollutants rejection and concentration efficiency by using synthetic seawater as the draw solution. It was found that when operating in PRO mode (active layer facing the draw solution), although the FO membrane exhibited higher osmotic water flux, more severe flux decline and reverse salt diffusion was also observed due to the more severe fouling of pollutants in the membrane support layer and accompanied fouling enhanced concentration polarization. In addition, although the water flux decline was shown to be lower for the FO mode (active layer facing the feed solution), irreversible membrane fouling was identified in both PRO and FO modes as the water flux cannot be restored to the initial value by physical flushing, highlighting the necessity of chemical cleaning in long-term operation. During the 7 cycles of filtration conducted in the experiments, the FO membrane exhibited considerably high rejection for TOC, COD, TP and $NH_4{^+}-N$ present in the wastewater. By optimizing the volume ratio of seawater draw solution/wastewater feed solution, a concentration factor of 3.1 and 3.7 was obtained for the FO and PRO modes, respectively. The results demonstrated the validity of the FO process for direct treatment of municipal wastewater by using seawater as the draw solution, while facilitating the subsequent utilization of concentrated wastewater for bioenergy production, which may have special implications for the coastline areas.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.432-436
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• 2004

The principle and methodology of risk assessment was applied to establish the quality standard of potential impurities of drinking water treatment chemicals. The impurities(arsenic, lead, cadmium, chromium, mercury, etc.) are regulated as the contained quantity of chemicals in Korea while they are regulated as the quality standard with the idea of 10% of the national safety drinking water standard in U.S.A(NSF) and Japan(JWWA). According to risk assessment of the current standard implemented in Korea, the excess cancer risk of arsenic and lead were determined in around $10^{-5}$ and the hazard quotient(HQ) of cadmium and chromium were below $10^{-2}$, respectively. And the standard concentration of the impurities are regulated as much as 2%~6% of the national drinking water quality standard. The values are more enforced rather than the standards in U.S.A(NSF) and Japan(JWWA) regulating the concentration of impurities the 10% of the national drinking water quality standard. We conclude that the impurities standard of drinking water treatment chemicals should be reconsidered comprehensively concerning the national safety drinking water quality standard and risk assessment.

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.355-361
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• 2018

Mold grows more easily when humidity is higher in indoor spaces, and as such is found more often on wetted areas in housing such as walls, toilets, kitchens, and poorly managed spaces. However, there have been few studies that have specifically assessed the level of mold in the indoor spaces of water-damaged housing in the Republic of Korea. We investigated the levels of airborne mold according to the characteristics of water damage types and explored the correlation between the distribution of mold genera and the characteristics of households. Samplings were performed from January 2016 to June 2018 in 97 housing units with water leakage or condensation, or a history of flooding, and in 61 general housing units in the metropolitan and Busan area, respectively. Airborne mold was collected on MEA (Malt extract agar) at flow rate of 100 L/min for 1 min. After collection, the samples were incubated at $25^{\circ}C$ for 120 hours. The cultured samples were counted and corrected using a positive hole conversion table. The samples were then analyzed by single colony culture, DNA extraction, gene amplification, and sequencing. By type of housing, concentrations of airborne mold were highest in flooded housing, followed by water-leaked or highly condensed housings, and then general housing. In more than 50% of water-damaged housing, the level of airborne mold exceeded the guideline of Korea's Ministry of Environment ($500CFU/m^3$). Of particular concern was the fact that the I/O ratio of water-damaged housing was greater than 1, which could indicate that mold damage may occur indoors. The distribution patterns of the fungal species were as follows: Penicillium spp., Cladosporium spp. (14%), Aspergillus spp. (13%) and Alternaria spp. (3%), but significant differences of their levels in indoor spaces were not found. Our findings indicate that high levels of mold damage were found in housing with water damage, and Aspergillus flavus and Penicillium brevicompactum were more dominant in housing with high water activity. Comprehensive management of flooded or water-damaged housing is necessary to reduce fungal exposure.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.2
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• pp.81-95
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• 2022

The present study was performed to investigate the effects of NH₃-N and nitrifying microorganisms on the increased BOD of downstream of the Yeongsan river in Gwangju. Water samples were collected periodically from the 13 sampling sites of rivers from April to October 2021 to monitor water qualities. In addition, the trends of nitrogenous biochemical oxygen demand (NBOD) and microbial clusters were analyzed by adding different NH₃-N concentrations to the water samples. The monitoring results showed that NH₃-N concentration in the Yeongsan river was 22 times increased after the inflow of discharged water from the Gwangju 1st public sewage treatment plant (G-1-PSTP). Increased NH₃-N elevated NBOD levels through the nitrification process in the river, consequently, it would attribute to the increase of BOD in the Yeongsan river. Meanwhile, there was no proportional relation between NBOD and NH₃-N concentrations. However, there was a significant difference in NBOD occurrence by sampling sites. Specifically, when 5 mg/L NH₃-N was added, NBOD of the river sample showed 2-4 times higher values after the inflow of discharged water from G-1-PSTP. Therefore, it could be thought other factors such as microorganisms influence the elevated NBOD levels. Through next-generation sequencing analysis, nitrifying microorganisms such as Nitrosomonas, Nitroga, and Nitrospira (Genus) were detected in rivers samples, especially, the proportion of them was the highest in river samples after the inflow of discharged water from G-1-PSTP. These results indicated the effects of nitrifying microorganisms and NH₃-N concentrations as important limiting factors on the increased NBOD levels in the rivers. Taken together, comprehensive strategies are needed not only to reduce the NH₃-N concentration of discharged water but also to control discharged nitrifying microorganisms to effectively reduce the NBOD levels in the downstream of the Yeongsan river where discharged water from G-1-PSTP flows.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2230-2231
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• 2008

최근에 국제유가의 급상승과 코토의정서 발의에 따른 대외적인 환경여건 변화로 인해 국내에서는 재생에너지 보급사업 및 에너지절감기술 관련 정책과 신기술이 활발히 추진되고 있다. 본 논문에서는 전기설비간의 주 동맥인 케이블 선정에 있어 케이블 굵기를 달리 하는 조건에 따라 전력손실량 변화의 실험값을 모의시험장치를 이용하여 취득하였고 이를 비교분석함으로 써 케이블 부문에서 에너지절감의 이론적 근거를 실증하였다. 또한, 수자원공사 수도사업장 중 취수장 전력시스템을 모델로 전력계통해석프로그램(PTW)을 이용하여 케이블 굵기 변화에 따른 전력손실량 변화를 모의하고 경제성분석을 통해 기존 케이블의 굵기 선정 방법을 재 고찰하고자 한다.