• 한국물환경학회지
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• 제31권5호
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• pp.556-562
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• 2015

In order to remove the organic substances and the nitrate-nitrogen contained in wastewater, some researchers have studied the simultaneous removal of organics and nitrogen by using different biocathode microbial fuel cells (MFCs). The operating conditions for removing the contaminants in the MFCs are the external resistances, HRTs, the concentration of the influent wastewater, and other factors. This study aimed to determine the effect of the external resistors and organic loading rates, from the changing HRT, on the removal of the organics and nitrogen and on the production of electric power using the Denitrification Biocathode - Microbial Fuel Cell (DNB-MFC). As regards the results of the study, the removal efficiencies of $SCOD_{Cr}$ did not show any difference, but the nitrate-nitrogen removal efficiencies were increased by decreasing the external resistance. The maximum denitrification rate achieved was $129.2{\pm}13.54g\;NO_3{^-}-N/m^3/d$ in the external resistance $1{\Omega}$, and the maximum power density was $3,279mW/m^3$ in $10{\Omega}$. When the DNB-MFC was operated with increasing influent organic and nitrate loading by reducing the HRTs, the $NO_3{^-}-N$ removal efficiencies were increased linearly, and the maximum nitrate removal rate was $1,586g\;NO^3{^-}-N/m^3/d$ at HRT 0.6 h.

• 한국화재소방학회논문지
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• 제34권4호
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• pp.78-86
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• 2020

본 연구에서는 공동주택 화재 시 부속실 가압 시스템의 방연풍속에 관하여 수치해석을 수행하였다. 수치해석을 통해 댐퍼의 급기량과 방화문에서의 방연풍속의 관계식을 선형적으로 나타내었고 국가화재안전기준인 방연풍속 0.7 m/s를 만족하는 댐퍼의 최소유량을 선정할 수 있었다. 댐퍼의 최소유량을 적용하여 댐퍼의 급기 방향과 설치 높이에 따라 방연속도를 분석하였다. 댐퍼의 급기 방향이 상향인 경우와 댐퍼가 높게 설치되었을 때 댐퍼의 급기 방향이 하향인 경우보다 방화문 상부에서 더 큰 방연풍속을 나타내었고 누출된 연기 농도가 더 낮은 것을 확인할 수 있었다. 따라서 방화문 상부에서 큰 방연풍속을 확보하는 것이 제연에 더 효율적일 것으로 판단된다.

• 보존과학회지
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• 제7권1호
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• pp.23-30
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• 1998

고대 유리제품에 대한 과학적 분석 조사는 다양한 정보를 제공한다. 이 중에서 조성 분석을 통하여 사용 원료, 제작 방법, 시대, 그리고 지역으로 그룹화하여 문화 수준과 유입 경로등을 이해하는 자료로 활용할 수 있다. 본 연구에서는 유리나 도자기의 유약 등으로 이루어진 문화재 시료에 대한 SEM-EDS의 정량분석 조건들을 설정하였고, 경남 김해 양동리에서 출토된 유리 구슬 조각 62점을 정량분석하였다. 분석 결과, 이 지역의 유리구슬은 알칼리계 유리로써 칼리계 유리는 AD 1세기, 소다계 유리는 AD 2세기 말~3세기 초부터 나타난 것으로 추정되었다. 유리의 색상은 전이금속 구리, 철, 그리고 망간의 함유량과 밀접한 관계가 있음을 보인다. 이 분석결과는 고대 유리구슬의 성분 함유량이 원료, 색상, 유구편년, 그리고 지역에 따라 그룹이 형성될 수 있음을 확인하였다.

• 한국수산과학회지
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• 제11권3호
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• pp.129-138
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• 1978

The contents of inorganic conservative constituents in the downstream water were determined in spring tides of every month from May 1977 to April 1978 at eight stations of Nagdong River. Samples were taken at the intervals of one or two hours from 7 a. m. to 7 p. m. at each station. Annual ranges and means of the chemical constituents over all the stations except station one, Kupo, ate as follows: pH 6.4-9.3, 7.7; electrical conductivity $0.085-0.345\times10^3\;\mu\mho/cm,\;0.196\times10^3\;\mu\mho/cm;$ chloride 5.8-50.0ppm, 17.7ppm: fluoride ND-0.19 ppm, 0.06 ppm: sulfate 5.5-41.1 ppm, 20.7 ppm; calcium 6-26 ppm, 17 ppm; magnesium 2.0-12.8 ppm, 5.1 ppm; sodium 7-26 ppm, 13 ppm; potassium 1.4-3.8 pprn, 2.3 ppm respectively. The seasonal variations of contents of the chemical constituents were not large and showed nearly definite values at all the stations except station one, Kupo. At station one, seasonal variations were large and the contents were excessively high due to inflow of seawater compared with other stations. The values over 50 ppm in chloride were not determined during the determination period at Mul Geum where the intake station for Busan city water is located. Most constituents except pH and fluoride were over the criteria for drinking water at Kupo, while at other stations only pH value was exceeded the upper limit of the criterion especially in summer period. The pH values tended to increase in the afternoon when water temperature was high. The chloride concentration was shown the highest value at station one, Kupo, with about 2 hours delay after high water of Busan harbour and 3-3.5 hours at Mul Geum.

• Journal of Plant Biology
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• 제17권2호
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• pp.53-62
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• 1974

A study was made on the primary production of Lake Changjamot during the spring season of 1973 by menas of the oxygen method. The stratification of temperature and dissolved oxygen were formed in May with the stratified structure of phytoplankton. The range of Secchi disc transparency was from 0.8m to 2.3m during the nine months of this investigation, which was begun in January, 1973. The value was lowest in early June when the phytoplankton blooming reached the peak. The concentration of PO4-P, NH3-N, NO3-N and NO3-N was reduced at the beginning of the phytoplankton blooming and increased again after May except PO4-P. It might have been caused by the inflow of the nitogenous fertilizer from the surrounding agricultural area since May when farming was started. The total amount of chlorophyll-a in the entire water column varied from 25mg/$m^2$ to 277mg/$m^2$ from January till September with the maximum value occurring in early June. These values show a considerable eutrophication of the in comparison with the data obtained in 1969. The daily gross production in the lake varied from a low of 655mgC/$m^2$ to a high of 2,859 mgC/$m^2$ during the spring season and this corresponds to the variation of the amount of chlorophyll. The total amount of daily respiration varied from 650mg C/$m^2$ in winter to 2,307 mg C/$m^2$ in late spring and exceeds gross primary production especially in late May showing the negative balance of daily production and consumption of organic material at that time. In conclusion, Lake Changjamot is a fairly productive and a moderately autotrophic lake and has been eutrophicated much during the past four years.

• 한국환경복원기술학회지
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• 제7권4호
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• pp.61-68
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• 2004

The purpose of this study was to develop environmentally friendly constructed wetland system in order to improve the environment. This system was constructed with two constructed wetlands andone pond. The size of the first and second wetland was 2.5m in length, 2.5m in width and 0.7m in depth for the first wetland and 0.6m in depth for the second wetland. Those were filled with pebbles with about 16~32mm in diameter from bottom to 20cm depth and onto the pebbles with about 0.5 mm in diameter sand in depth 40cm. The first constructed Wetland was planted with pragmites communis. The second was planted with Iris pseudoacorus and Acorus calamus var. aneustatus.A vertical flow system was used in the first constructed wetland and a horizontal flow system in the second. The water of outflow from the second wetland flowed into the pond. This system was installed in Yangpyeong, Kyunggi Province. The Quality of inflow and outflow were analyzed at the first time from May 20 to May 30, 2002 and at second time from June 10 to July 18, 2002. At the second period wetland was implanted with microbes in order to improve the efficiency of constructed wetlands. Following standard methods for wastewater, BOD, COD, SS, T-N and T-P were analyzed. This system was effective in reducing COD, BOD, SS, T-N and T-P level. The result shows that wastewater was purified through constructed wetland system with plants and highly purified with microbes especially in T-P. The Average total phosphorous concentration of influent and effluent in constructed wetland with microbes was 2.8mg/${\ell}$ L and 0.21mg/${\ell}$ respectively. This system can be used in rural community because this is not only effective on purification of sewage but also is harmonized with the surrounding nature.

• Environmental Analysis Health and Toxicology
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• 제25권3호
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• pp.215-222
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• 2010

The market size of engineered nanoparticles is rapidly increasing due to the fast application of nanotechnologies into different industries and consumer products. The development of new technology and materials has improved human's quality of life, but it also entails the possibility of exposure to new materials. In this study, we compared the distribution in the body by the inflow of silver nanoparticles having another diameter and shape at 1 h or 24 h after injection via the tail vein. And, we compared the cell composition and cytokine concentration in BAL fluid, and histopathological changes. As results, discharge of silver nanoparticles having small diameter and sphere shape was more rapid than that of big diameter or plate shape. It is estimated that the toxicity in liver and lung was proportional to accumulation level. The persistence of inflammation was also longer in mice treated with plate shape. Consequently, we suggest that the first choice of silver nanoparticles having small diameter and sphere shape in applying is desirable.

• 상하수도학회지
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• 제33권2호
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• pp.141-150
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• 2019

Total organic carbon(TOC) was introduced as the water quality index of the rivers and lakes in 2013. This paper evaluated factors affecting effluent TOC concentrations and treated and discharged loads of existing publicly owned treatment works(POTWs). For selected POTWs with greater treatment capacity than $500m^3/day$, factorial analysis was used to consider effects of kinds of biological treatment processes, inflow of other types of wastewater(industrial, livestock, landfill leachate wastewater, etc.) with domestic wastewater, sewer separation rate, and effluent discharging zones in which different effluent criteria applied. As a result, those factors did not show significant effect on effluent TOC concentration of POTWs in effluent discharging zone I and II. However, In effluent discharging zone III and IV, kinds of biological treatment processes, the inclusion of other waste in influent of domestic wastewater, and the sewer separation rate were significant factors. The treated TOC load in POTWs was also not affected significantly by the variables set in this study. On the other hand, those three factors influenced significantly on the TOC load discharged to water bodies. The sum of factorial effects and the contribution rate of three factors to the discharged TOC load was 60.23 and 41%, 59.57 and 41%, and 42.04 and 18%, respectively.

• 한국물환경학회지
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• 제34권6호
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• pp.678-687
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• 2018

The purpose of this study was to understand the unique and complicated feature of urban stream receiving various inflows. The Yangjae stream, the second tier of the Han River, runs through the southern parts of Seoul, Korea and its middle part flows on the boundary of Seoul where land use is actively changing. Stream flow was greatly influenced by rainfall. Other than rainfall events, effluent discharge from wastewater treatment plant (WWTP) comprised 51 % of stream flux. As a result, majority ions water chemistry was changed at the receiving zone of the discharged effluent (Zone A). Its contribution increased to 69.9 % at the second sampling period with low stream flow. In the middle zone, inflows from the northern area, recently developed to a residential district showed low $NO_3-N$ and high $HCO_3$, Ca, $SO_4$, and $SiO_2$ indicating the effects of groundwater and concrete. One inflow (T-8), with extremely high Na and Cl, median $SiO_2$, was assessed to have anthropogenic influence, however its contribution to main stream was under 1 %. Road construction near Y-13 also affected water chemistry leading to the highest Na and Cl concentration. These hydro chemical changes can be critically used to evaluate the changes in water budget and fate of chemicals in a peri-urban watershed occasioned by human activities on the Yangjae.

• 한국물환경학회지
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• 제35권1호
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• pp.19-27
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• 2019

The purpose of this study is to evaluate the water quality and phytoplankton community in Bukhan River which account for 44.4 % of the total inflow into Lake Paldang, using multivariate statistical techniques (i.e., correlation analysis, principal component analysis (PCA)/factor analysis (FA)). Water samples were collected from March to November 2015 and the following parameters measured; water temperature, pH, DO, EC, SS, BOD, Chl-a, COD, TN, $NO_3-N$, $NH_3-N$, TP, DTP, $PO_4-P$, and phytoplankton community. The water quality of the main stream and the tributaries were not significantly different apart from the relatively high concentration of BOD, COD and nutrients recorded in MH. The highest cell density of Stephanodiscus hantzschii and Merismopedia glauca dominated phytoplankton was observed in PD. Based on the correlation analysis, total phytoplankton and cyanophyceae were highly correlated with BOD, COD and nutrients. PCA/FA resulted in four main factors accounting for 82.240 % of the total variance in the water quality dataset. The group of component 1 (TN, DTN, DO, $NO_3-N$, water temperature) and component 2 ($PO_4-P$, T-P, DTP, SS) were classified as nutrient element factor whereas component 3 (Chl-a, COD, BOD, $NH_3-N$, pH) was related to organic substances. Hence, the identification of the main potential environmental pollution factors in Bukhan River will help policy makers make better and more informed decisions on how to improve the water quality.