• 상하수도학회지
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• 제34권6호
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• pp.463-471
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• 2020

A 1,000 ㎥/d DAF(dissolved air flotation) pilot plant was installed to evaluate the performance of the floating process using the Nakdong River. Efficiency of various DAF operations under different conditions, such as hydraulic loading rate, coagulant concentration was evaluated in the current research. The operation conditions were evaluated, based on the removal or turbidity, TOC(total organic carbon), THMFP(trihalomethane formation potential), Mn(manganese), and Al(aluminum). Also, particle size analysis of treated water by DAF was performed to examine the characteristics of particles existing in the treated water. The turbidity removal was higher than 90%, and it could be operated at 0.5 NTU or less, which is suitable for the drinking water quality standard. Turbidity, TOC, and THMFP resulted in stable water quality when replacing the coagulant from alum to PAC(poly aluminum chloride). A 100% removal of Chl-a was recorded during the summer period of the DAF operations. Mn removal was not as effective as where the removal did not satisfy the water quality standards for the majority of the operation period. Hydraulic loading of 10 m/h, and coagulant concentrations of 40 mg/L was determined to be the optimal operating conditions for turbidity and TOC removal. When the coagulant concentration increases, the Al concentration of the DAF treated water also increases, so coagulant injection control is required according to the raw water quality. Particle size distribution results indicated that particles larger than 25 ㎛ showed higher removal rates than smaller particles. The total particel count in the treated water was 2,214.7 counts/ml under the operation conditions of 10 m/h of hydraulic loading rate and coagulant concentrations of 60 mg/L.

• 한국물환경학회지
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• 제22권5호
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• pp.943-951
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• 2006

Spatial distribution of water pollution in the Gap Stream was investigated from October to November, 2005. Sampling was conducted three times including effluents discharged from a wastewater treatment plant (WWTP) and a dam reservoir during the low-flow period. As a typical urban stream, total nitrogen and inorganic nitrogen concentrations increased toward downstream. Ammonia concentration was the highest in the treated water of the wastewater treatment plant and the lowest nitrate concentration was found in the effluent of the dam reservoir. A part of soluble reactive phosphorous (SRP) in total phosphorous was 22~54% in the upstream reach of WWTP in the Gap Stream whereas 68~73% in the downstream reach. Mean chlorophyll-a concentration ranged from 1.6 to $11.0{\mu}g/L$ and it tends to increase toward downstream except for WWTP effluent. As expected, untreated wastewater and WWTP effluent were suggested as the major sources of water pollution in the Gap Stream. In this study, the water pollution of the Gap Stream is a significant undergoing typical eutrophication, caused by excessive phosphorus and nitrogen nutrients from WWTP located in the watershed. As a result, the critical factor for the water pollution was evaluated to dissolved inorganic nitrogen and phosphorus nutrients. Particularly, SRP is a most important for the eutrophication. It suggest that may occur in the most urban streams of Korean peninsula. Therefore, because the necessity of water pollution management in the urban stream, inorganic N and P nutrients should be included as an essential component of water quality criteria in the advanced water quality project of Korean Government by enforcing of water quality assessment and total maximum daily loads (TMDLs).

• 한국습지학회지
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• 제6권1호
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• pp.149-166
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• 2004

한강 하구의 염분 및 생태 환경에 관한 연구를 위하여 기존에 발표된 논문과 국립수산과학원의 국가해양환경측정망 자료를 이용하여 한강 하구의 염분 분포 특성을 구명하였으며, 염분과 연관하여 동식물플랑크톤, 저서생물 및 어류플랑크톤의 분포를 논의하였다. 염분의 시공간적 분포를 고려할 때 인천북항 주변 해역은 계절에 무관하게 연중 한강 유입수의 직접적인 영향을 받고 있으며, 담수 유입량이 많은 하계에는 팔미도 해역까지 담수 영향권이 확대되었다. 반면 해수의 직접적인 영향을 받는 상한선은 한강 본류인 경기도 김포시 고촌면 신곡리의 신곡수중보에 이르며, 해침이 상시적으로 발생하는 수역은 이보다 더 하류인 경기도 김포시 하성면 전류리로 판단된다. 동식물플랑크톤의 분포는 담수 및 해수 지역에서 혼재되어 분포하며, 일반적으로 염분의 분포 범위보다 훨씬 광범위한 분포를 보였다. 그러나 기수성 어류플랑크톤은 매우 제한된 수역에 분포하는 반면, 성어는 그 분포범위가 담수에서 해수에 이르는 광범위한 분포를 보였다. 경험적 분석에 의한 한강하구 환경의 문제점은 1)한강 하구 및 유수지역의 개발 압력에 따른 환경 파괴, 2)갯벌 매립에 의한 조간대 상실, 3)군사용 철책에 의한 육수전이환경(陸水轉移環境)의 생태적 단절이 매우 심각하였다.

• 한국물환경학회지
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• 제29권6호
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• pp.762-776
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• 2013

Load duration curve was applied to determine important water quality parameter control term for improvement of Paldang lake water quality. Load duration curve was analyzed with long term data from 1985 to 2012 including water quality, flow rate and climate state of Paldang water environment. From the result of flow rate patterns of paldang lake, differences between high and low flow rate of each year showed tendency of increase because rainfall characteristics of paldang lake watershed were changed by climate exchange. Both of land use state of upper Paldang lake watershed and number of limit excess from load duration curve indicated that seasonal action related with land use such as agricultural fertilizer distribution in upper watershed affected Paldang lake water quality. So focused BOD (biological oxygen demand) management during spring season from march to June is required to control organic materials in Paldand lake. The main affecting factor of TOC (total organic carbon) increase in Paldang lake was initial rainfall after march. T-N (total nitrogen) kept increasing during research period, so enhancement of T-N standard is needed to T-N control. Initial rainfall and increase of temperature during spring season from March to June showed a positive correlation with TP (total phosphorus) and Chl-a, respectively.

• 대한환경공학회지
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• 제37권8호
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• pp.472-479
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• 2015

낙동강 수계에서의 자외선 차단제류 검출현황을 조사한 결과, 본류 및 지류 20지점 중 5지점에서 EHS, BP-3, 4-MBC, BZC 및 EHMC 5종이 검출되었으며, 본류에서는 검출되지 않았다. 지류의 경우는 금호강 상류, 신천, 금호강 하류, 진천천 및 양산천에서 EHS가 ND~60.8 ng/L, BP-3가 ND~72.1 ng/L, 4-MBC가 ND~57.2 ng/L, BZC가 ND~60.1 ng/L 및 EHMC가 ND~85.2 ng/L의 농도로 검출되었다. 낙동강 주변에 위치한 11개 하수처리장 방류수들에서는 EHS, BP-3, 4-MBC, BZC 및 EHMC 5종이 각각 ND~89.3 ng/L, ND~90.8 ng/L, ND~88.1 ng/L, ND~118.5 ng/L 및 ND~104.4 ng/L의 농도로 검출되었다. 낙동강 수계 및 낙동강 주변에 위치한 11개 하수처리장 방류수들에서의 계절별 자외선 차단제류의 분포비율은, 6월과 9월에는 대체적으로 유사한 분포 특성을 나타내었으나, 4월과 11월에는 검출농도 뿐만 아니라 구성종 비율의 변화폭도 매우 크게 나타났다.

• 한국물환경학회지
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• 제30권2호
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• pp.148-158
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• 2014

In order to assess the effect of TMDLs management and improve that in the future, it is necessary to analyze long-term changes in water quality during management period. Therefore, long term trend analysis of BOD was performed on thirty monitoring stations in Geum River TMDL unit watersheds. Nonparametric trend analysis method was used for analysis as the water quality data are generally not in normal distribution. The monthly median values of BOD during 2004~2010 were analyzed by Seasonal Mann-Kendall test and LOWESS(LOcally WEighted Scatter plot Smoother). And the effect of Total Maximum Daily Loads(TMDLs) management on water quality changes at each unit watershed was analyzed with the result of trend analysis. The Seasonal Mann-Kendall test results showed that BOD concentrations had the downward trend at 10 unit watersheds, upward trend at 4 unit watersheds and no significant trend at 16 unit watersheds. And the LOWESS analysis showed that BOD concentration began to decrease after mid-2009 at almost all of unit watersheds having no trend in implementation plan watershed. It was estimated that TMDLs improved water quality in Geum River water system and the improvement of water quality was made mainly in implementation plan unit watershed and tributaries.

• 지질공학
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• 제30권3호
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• pp.379-397
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• 2020

본 연구에서는 1922년부터 2019년까지 동래온천수의 장기적인 온천수 수질 변화 특성을 살펴보았다. Mann-Kendall 분석과 Sen의 기울기에 의해서 동래온천수의 장기적인 수질 특성 변화를 분석하면, 온도, Ca, SiO₂, HCO₃는 증가 추세를 보이는 반면에 EC, Na, K, Mg, Cl, SO₄은 감소 추세를 보이거나 또는 거의 추세 변화를 보이지 않는다. 동래온천수의 수질유형은 시간경과에도 변하지 않고 Na-Cl형에 안정적으로 속하고 있다. 2004년, 2009년, 2014년, 2019년의 수질 자료를 이용한 공간 분포도에 의하면, 시기별로 변동을 보이며, 시료 채취 지점에 따라 값의 변화를 보인다. 이는 장기적인 온천수 개발에도 불구하고 동래온천수의 공간적인 수질 특성은 거의 일정하다는 것을 지시한다.

• International Journal of Air-Conditioning and Refrigeration
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• 제16권2호
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• pp.37-43
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• 2008

The air and water flow distributions are experimentally studied for a round header - ten flat tube configuration. Three different inlet orientation modes (parallel, normal, vertical) were investigated. Tests were conducted with downward flow configuration for the mass flux from 70 to $130kg/m^2s$, quality from 0.2 to 0.6, non-dimensional protrusion depth (h/D) from 0,0 to 0.5. It is shown that, for almost all the test conditions, vertical inlet yielded the best flow distribution, followed by normal and parallel inlet. Possible explanation is provided using flow visualization results.

• 한국식품저장유통학회지
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• 제30권2호
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• pp.224-234
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• 2023

We analyzed the major quality characteristics of red pepper powders from various regions and predicted these characteristics nondestructively using shortwave infrared hyperspectral imaging (HSI) technology. We conducted partial least squares regression analysis on 70% (n=71) of the acquired hyperspectral data of the red pepper powders to examine the major quality characteristics. R_c² values of ≥0.8 were obtained for the ASTA color value (0.9263) and capsaicinoid content (0.8310). The developed quality prediction model was validated using the remaining 30% (n=35) of the hyperspectral data; the highest accuracy was achieved for the ASTA color value (R_p²=0.8488), and similar validity levels were achieved for the capsaicinoid and moisture contents. To increase the accuracy of the quality prediction model, we conducted spectrum preprocessing using SNV, MSC, SG-1, and SG-2, and the model's accuracy was verified. The results indicated that the accuracy of the model was most significantly improved by the MSC method, and the prediction accuracy for the ASTA color value was the highest for all the spectrum preprocessing methods. Our findings suggest that the quality characteristics of red pepper powders, even powders that do not conform to specific variables such as particle size and moisture content, can be predicted via HSI.

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.717-727
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• 2006

The present study experimentally investigated the effect of flow direction and other flow parameters on two-phase flow distribution of refrigerants at a T-junction, and also suggested a prediction model for refrigerant in a T-junction by modifying previous model for air-water flow. R-22, R-134a, and R-410A were used as test refrigerants. As geometric parameters, the direction of the inlet or branch tube and the tube diameter ratio of branch to inlet tube were chosen. The measured data were compared with the values predicted by the models developed for air-water or steam-water mixture in the literature. We propose a modified model for application to the reduced T-junction and vertical tube orientation. Among the geometric parameters, the branch tube direction showed the biggest sensitivity to the mass flow rate ratio for the gas phase, while the inlet quality showed the biggest sensitivity to the mass flow rate ratio among the inlet flow parameters.