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상하수도학회지 update

Journal of the Korean Society of Water and Wastewater

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수록정보
34권4호(2020) |수록논문 수 : 7
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35권4호(2021년 08월) 수록논문
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KCI등재

1대한상하수도학회지 목차

저자 : 대한상하수도학회

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 35권 4호 발행 연도 : 2021 페이지 : pp. 1-2 (2 pages)

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2베이지안 최적화를 통한 저서성 대형무척추동물 종분포모델 개발

저자 : 고병건 ( Byeonggeon Go ) , 신지훈 ( Jihoon Shin ) , 차윤경 ( Yoonkyung Cha )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 35권 4호 발행 연도 : 2021 페이지 : pp. 259-275 (17 pages)

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This study explored the usefulness and implications of the Bayesian hyperparameter optimization in developing species distribution models (SDMs). A variety of machine learning (ML) algorithms, namely, support vector machine (SVM), random forest (RF), boosted regression tree (BRT), XGBoost (XGB), and Multilayer perceptron (MLP) were used for predicting the occurrence of four benthic macroinvertebrate species. The Bayesian optimization method successfully tuned model hyperparameters, with all ML models resulting an area under the curve (AUC) > 0.7. Also, hyperparameter search ranges that generally clustered around the optimal values suggest the efficiency of the Bayesian optimization in finding optimal sets of hyperparameters. Tree based ensemble algorithms (BRT, RF, and XGB) tended to show higher performances than SVM and MLP. Important hyperparameters and optimal values differed by species and ML model, indicating the necessity of hyperparameter tuning for improving individual model performances. The optimization results demonstrate that for all macroinvertebrate species SVM and RF required fewer numbers of trials until obtaining optimal hyperparameter sets, leading to reduced computational cost compared to other ML algorithms. The results of this study suggest that the Bayesian optimization is an efficient method for hyperparameter optimization of machine learning algorithms.

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3산화철계 가중응집제가 활성슬러지의 침전성 및 탈수성에 미치는 영향

저자 : 양혜지 ( Hyeji Yang ) , 김용범 ( Yongbum Kim ) , 최영균 ( Younggyun Choi )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 35권 4호 발행 연도 : 2021 페이지 : pp. 277-284 (8 pages)

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The ballasted flocculation effects of the mill scale and magnetite on activated sludge were investigated. Both ballasted flocculants (BF) could remarkably improve the sludge settleability in terms of zone settling velocity (ZSV) and sludge volume index (SVI). With the BF dosage of 0.2 to 2.0 g-BF/g-SS, the magnetite particles showed better efficiency on improving settling behavior of activated sludge than the mill scale due to higher surface area and hydrophobic property. The efficiency of SVI30 with magnetite injection was 2.5 to 11.3% higher than mill scale injection and that of the ZSV appreciated from 23.7% to 44.4% for magnetite injection. Averaged floc size of the BF sludge with magnetite dosage (0.5 g-BF/g-SS) was 2.3 times higher than that of the control sludge. Dewaterability of the sludge was also greatly improved by addition of the BF. The specific resistance to filtration (SRF) was reduced exponentially with increasing the dosage of BF. However, the BF's particle size effect on the SRF looks to be marginal. Consequently, for improving the dewaterability, the BF played a physical role to remove the pore water of the biological flocs by intrusive attachment and a chemical role to induce aggregation of the flocs by charge neutralization.

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4응집-UF 전처리 공정이 압력지연삼투 공정에 미치는 영향

저자 : 고길현 ( Gilhyun Goh ) , 김수현 ( Suhyun Kim ) , 김정선 ( Jungsun Kim ) , 강임석 ( Limseok Kang )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 35권 4호 발행 연도 : 2021 페이지 : pp. 285-292 (8 pages)

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Osmotic power is to produce electric power by using the chemical potential of two flows with the difference of salinity. Water permeates through a semipermeable membrane from a low concentration feed solution to a high concentration draw solution due to osmotic pressure. In a pressure retarded osmosis (PRO) process, river water and wastewater are commonly used as low salinity feed solution, whereas seawater and brine from the SWRO plant are employed as draw solution. During the PRO process using wastewater effluent as feed solution, PRO membrane fouling is usually caused by the convective or diffusive transport of PRO which is the most critical step of PRO membrane in order to prevent membrane fouling. The main objective of this study is to assess the PRO membrane fouling reduction by pretreatment to remove organic matter using coagulation-UF membrane process. The experimental results obtained from the pretreatment test showed that the optimum ferric chloride and PAC dosage for removal of organic matter applied for the coagulation and adsorption process was 50 mg/L as FeCl3 (optimum pH 5.5). Coagulation-UF pretreatment process was higher removal efficiency of organic matter, as also resulting in the substantial improvement of water flux of PRO membrane.

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5정수처리 공정 적용을 위한 MCDI (Membrane Capacitive Deionization) Module의 수용액 내 TDS 제거 특성에 관한 연구

저자 : 오창석 ( Changseog Oh ) , 안주석 ( Jusuk An ) , 오현제 ( Hyun-je Oh )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 35권 4호 발행 연도 : 2021 페이지 : pp. 293-300 (8 pages)

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Recently, various researches have been studied, such as water treatment, water reuse, and seawater desalination using CDI (Capacitive deionization) technology. Also, applications like MCDI (Membrane capacitive deionization), FCDI (Flow-capacitive deionization), and hybrid CDI have been actively studied. This study tried to investigate various factors by an experiment on the TDS (Total dissolved solids) removal characteristics using MCDI module in aqueous solution. As a result of the TDS concentration of feed water from 500 to 2,000 mg/L, the MCDI cell broke through faster when the higher TDS concentration. In the case of TDS concentration according to the various flow rate, 100 mL/min was stable. In addition, there was no significant difference in the desorption efficiency according to the TDS concentration and method of backwash water used for desorption. As a result of using concentrated water for desorption, stable adsorption efficiency was shown. In the case of the MCDI module, the ions of the bulk solution which is escaped from the MCDI cell to the spacer during the desorption process are more important than the concentration of ions during desorption. Therefore, the MCDI process can get a larger amount of treated water than the CDI process. Also, prepare a plan that can be operated insensitive to the TDS concentration of backwash water for desorption.

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6키토산 비드의 교차결합(crosslinking)과 건조공정이 흡착속도에 미치는 영향

저자 : 신정우 ( Jeongwoo Shin ) , 김태훈 ( Taehoon Kim ) , 이영민 ( Youngmin Lee ) , 안병렬 ( Byungryul An )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 35권 4호 발행 연도 : 2021 페이지 : pp. 301-309 (9 pages)

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Chitosan, natural organic polymer, has been applied in water treatment as adsorbent due to non-toxic for human being. The amino group as functional group, can interacts with cation and anion at the same time. The prepared chitosan bead (HCB) was crosslinked to increase chemical stability (HCB-G) and both HCB and HCB-G were prepared to increase physical strength by drying referred to DCB and DCB-G, respectively. The adsorption effect for crosslinking and drying for four types of chitosan bead was tested using pseudo fist order (PFO), pseudo second order (PSO), and intraparticle diffusion model (ID). Regardless of PFO and PSO, the order of K, rate constant, is as followed: HCB > HCB-G > DCB > DCB-G for Cu(II) and phosphate. Drying leading to contraction of bead significantly reduced adsorption rate due to reduce the porosity of chitosan. In addition, crosslingking also negatively effect on adsorption rate. When compared with Cu(II) using hydrogel bead, phosphate showed higher value than Cu(II) for PFO and PSO. The application of ID showed that both hydrogel beads (HCB and HCB-G) obtained a very low R2 ranging to 0.37 to 0.81, while R2 can be obtained to over 0.9 for DCB and DCB-G, indicting ID is appropriate for low adsorption rate.

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KCI등재

1대한상하수도학회지 목차

저자 : 대한상하수도학회

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 34권 4호 발행 연도 : 2020 페이지 : pp. 1-2 (2 pages)

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2상수원수 수질저하가 정수처리 비용에 미치는 영향

저자 : 김진근 ( Jinkeun Kim )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 34권 4호 발행 연도 : 2020 페이지 : pp. 239-250 (12 pages)

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In this study, effects of five raw water quality parameters (turbidity, odor compounds caused by algae, filter clogging caused by algae, pH increase caused by algae, and organic matter) on improvements and operations costs of typical water treatment plant (WTP) were estimated. The raw water quality parameters were assumed the worst possible conditions based on the past data and costs were subsequently estimated. Results showed that new water treatment facilities were needed, such as a selective intake system, an advanced water treatment processes, a dual media filter, a carbonation facility, and a re-chlorination facility depending on water quality. Furthermore, changes needed to be made in WTP operations, such as adding powered activated carbon, increasing the injection of chlorine, adding coagulation aid, increasing the discharge of backwashed water, and increasing the operation time of dewatering facilities. Such findings showed that to reliably produce high-quality tap water and reduce water treatment costs, continuous improvements to the quality of water sources are needed.

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3와이블 분포함수를 이용한 하수관로 노후도 추정

저자 : 강병준 ( Byongjun Kang ) , 유순유 ( Soonyu Yoo ) , 박규홍 ( Kyoohong Park )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 34권 4호 발행 연도 : 2020 페이지 : pp. 251-258 (8 pages)

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Sewer deterioration models are needed to forecast the remaining life expectancy of sewer networks by assessing their conditions. In this study, the serious defect (or condition state 3) occurrence probability, at which sewer rehabilitation program should be implemented, was evaluated using four probability distribution functions such as normal, lognormal, exponential, and Weibull distribution. A sample of 252 km of CCTV-inspected sewer pipe data in city Z was collected in the first place. Then the effective data (284 sewer sections of 8.15 km) with reliable information were extracted and classified into 3 groups considering the sub-catchment area, sewer material, and sewer pipe size. Anderson-Darling test was conducted to select the most fitted probability distribution of sewer defect occurrence as Weibull distribution. The shape parameters (β) and scale parameters (η) of Weibull distribution were estimated from the data set of 3 classified groups, including standard errors, 95% confidence intervals, and log-likelihood values. The plot of probability density function and cumulative distribution function were obtained using the estimated parameter values, which could be used to indicate the quantitative level of risk on occurrence of CS3. It was estimated that sewer data group 1, group 2, and group 3 has CS3 occurrence probability exceeding 50% at 13th-year, 11th-year, and 16th-year after the installation, respectively. For every data groups, the time exceeding the CS3 occurrence probability of 90% was also predicted to be 27th- to 30th-year after the installation.

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4가축분뇨 혐기 소화액 처리를 위한 막 증발과 역삼투 공정 성능 비교

저자 : 김승환 ( Seunghwan Kim ) , 조진우 ( Jinwoo Cho )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 34권 4호 발행 연도 : 2020 페이지 : pp. 259-266 (8 pages)

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In this study, a pilot-scale (3 m3/day) membrane distillation (MD) process was operated to treat digestate produced from anaerobic digestion of livestock wastewater. In order to evaluate the performance and energy cost of MD process, it was compared with the pilot scale (10 m3/day) reverse osmosis (RO) process, expected competitive process, under same feed condition. As results, MD process shows stable permeate flux (average 10.1 L/m2/hr) until 150 hours, whereas permeate flux of RO process was decreased from 5.3 to 1.5 L/m2/hr within 24 hours. In the case of removal of COD, TN, and TP, MD process shows a high removal rate (98.7, 93.7, and 99% respectively) stably until 150 hours. However, in the case of RO process, removal rate was decreased from 91.6 to 69.5% in COD and from 93.7 to 76.0% in TP during 100 hours of operation. Removal rate of TN in RO process was fluctuated in the range of 34.5-62.9% (average 44.6%) during the operation. As a result of energy cost analysis, MD process using waste heat for heating the feed shows 18% lower cost compare with RO process. Thus, overall efficiency of the MD process is higher then that of the RO process in terms of permeate flux, removal rate of salts, and operating cost (in the case of using waste heat) in treating the anaerobic digestate of livestock wastewater.

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5관 세척에 따른 색도성 물질의 제거 효과

저자 : 이호민 ( Ho-min Lee ) , 최태호 ( Tae-ho Choi ) , 윤현우 ( Hyun-woo Yun ) , 김동홍 ( Dong-hong Kim ) , 배철호 ( Cheol-ho Bae )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 34권 4호 발행 연도 : 2020 페이지 : pp. 267-276 (10 pages)

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In this study, air scouring cleaning was selected and applied among 5 small blocks (S1~S5) in domestic S cities to analyze the cleaning effect of particles causing discoloration. In order to identify the cleaning effect, 10 locations were selected as water quality investigation point, such as the stagnant or water mains ends. Removal of solids, variation of particle components, weight and concentration were analyzed. And the level of the cleanness of the surface inside water mains using endoscope was investigated. As a result of analysis, the solids discharged after cleaning were mainly sand and gravel, pieces related to pipe materials, and corrosion products. As a result of analyzing the concentrated particles of the filter before and after cleaning, it was found that the change in discoloration on the filter was large. In addition, as a result of comparing the weight and the concentration of the particles, it was found that the particles causing discoloration were significantly removed after cleaning. From the results of the endoscopy, it was confirmed that most of the precipitated and accumulated dark yellow discoloration matters inside water mains were removed through cleaning. Therefore, it seems that the particles causing discoloration in water decreased after cleaning. Therefore, it is expected that, if properly cleaning was applied, matters that cause discoloration can be removed from the water mains, and customer's complaints can also be reduced through water quality improvement.

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6머신러닝 기법을 활용한 낙동강 중류 지역의 Chl-a 예측 알고리즘 비교 연구(수질인자 및 수량 중심으로)

저자 : 이상민 ( Sang-min Lee ) , 박경덕 ( Kyeong-deok Park ) , 김일규 ( Il-kyu Kim )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 34권 4호 발행 연도 : 2020 페이지 : pp. 277-288 (12 pages)

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In this study, we performed algorithms to predict algae of Chlorophyll-a (Chl-a). Water quality and quantity data of the middle Nakdong River area were used. At first, the correlation analysis between Chl-a and water quality and quantity data was studied. We extracted ten factors of high importance for water quality and quantity data about the two weirs. Algorithms predicted how ten factors affected Chl-a occurrence. We performed algorithms about decision tree, random forest, elastic net, gradient boosting with Python. The root mean square error (RMSE) value was used to evaluate excellent algorithms. The gradient boosting showed 10.55 of RMSE value for the Gangjeonggoryeong (GG) site and 11.43 of RMSE value for the Dalsung (DS) site. The gradient boosting algorithm showed excellent results for GG and DS sites. Prediction value for the four algorithms was also evaluated through the Receiver operating characteristic (ROC) curve and Area under curve (AUC). As a result of the evaluation, the AUC value was 0.877 at GG site and the AUC value was 0.951 at DS site. So the algorithm's ability to interpret seemed to be excellent.

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7하수관로의 면단위 및 선단위 정비 우선순위 결정을 위한 AHP-PROMETHEE기법의 적용

저자 : 안호성 ( Hosung Ahn ) , 유순유 ( Soonyu Yoo ) , 이태훈 ( Taehoon Lee ) , 박규홍 ( Kyoohong Park )

발행기관 : 대한상하수도학회 간행물 : 상하수도학회지 34권 4호 발행 연도 : 2020 페이지 : pp. 289-301 (13 pages)

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Since sewer rehabilitation program requires long construction period and enormous capital investment, determination of rehabilitation priorities is important with systematic planning considering appropriate evaluation parameters. In this research, we applied PROMETHEE(Preference Ranking Organization METHod for Evaluations) known as very objective and scientific multi-criteria decision-making analysis, using the weights determined by AHP(Analytic Hierarchy Process) for the selected sewer evaluation items to calculate the rehabilitation priorities for each sewer sub-catchment in basin Gusan 1 of Seoul. Preference functions and preference thresholds were estimated for each criterion of ratio of lack of hydraulic capacity of sewers, defect ratio, ratio of sewers with velocity less than its minimum criteria, and density of sewers in the sub-catchment. As a result, it was found that region d had the first priority among four sub-catchments. For each and every sewer located in region d, we could also rank sewers to be rehabilitated urgently.

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