• 제목/요약/키워드: Smart concentrations

검색결과 64건 처리시간 0.026초

해수 환경에서 포말분리기 운전 조건에 따른 고형물 제거 특성 (Suspended Solids Removal Performance of a Foam Fractionator with Different Operating Conditions in Seawater)

  • 서준혁;이재만;김봉재;김병기;김유희;박정환
    • 한국수산과학회지
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    • 제55권3호
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    • pp.328-337
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    • 2022
  • This study investigated the removal performance of a foam fractionator under seawater conditions. The foam fractionator was tested using a 3×3×3 factorial design for operating conditions by combining different solids concentrations (SS; 1, 5, and 10 mg·L-1), surface air velocities (SAV; 1.1, 1.5, and 2.1 cm·sec-1), and hydraulic residence times (HRT; 1, 3, and 6 min) at 16℃. Performance parameters such as daily solids removal rate and efficiency were measured, and a multi-regression model equation was developed accordingly. The daily solids removal rate and removal efficiency varied with the experimental conditions and ranged from 0.14-2.33 g-solids·m-3-air·day-1 and 8.9-96.7 %, respectively. Overall, the daily solids removal rate increased with increasing SS and SAV and decreasing HRT, whereas the removal efficiency increased with increasing SAV and HRT and decreasing SS. The daily solids removal rate (g-solids·m-3-air·day-1) of the foam fractionator for SAV (cm·sec-1), SS (mg·L-1) and HRT (min) were described by the following multi-regression model: Daily solids removal rate [f(z)]=-0.118+0.422SAV+0.094HRT+0.141SS (r2=0.873).

지하수 내 중금속 모니터링을 위한 diffusive gradients in thin films의 적용 가능성 평가 (Feasibility of Diffusive Gradients in Thin Films for Monitoring Heavy Metals in Groundwater)

  • 심규영;박광진;이승우;최종민;최수빈;안진성;남경필
    • 한국지하수토양환경학회지:지하수토양환경
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    • 제29권4호
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    • pp.12-20
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    • 2024
  • Diffusive gradients in thin films (DGT) are passive sampling devices used to determine the time-weighted average concentrations (TWAC) of contaminants. To ensure accurate performance in groundwater, it is crucial to identify environmental characteristics and maintain optimal operational conditions. This study examined the deployment time required to reach effective capacity, the thickness of the diffusive boundary layer (DBL) under stagnant water conditions, and biofilm formation on the DGT surface using groundwater samples. When using DGT with Chelex gel (A=3.14 cm2), the effective capacity was 0.7 ㎍ for Cd and 250 ㎍ for Zn, with a deployment time of 24 h. Lower Cd accumulation was due to the competition effect of coexisting ions. The DBL thickness under stagnant conditions was 0.074 cm, 93% of the diffusion gel's thickness (0.08 cm). Neglecting DBL thickness in TWAC calculations led to a 79% decrease in the determined concentration. No biofouling was observed during the 28-d DGT deployment in groundwater. In conclusion, it is essential to consider the appropriate deployment time, DBL thickness, and biofilm formation to ensure accurate DGT performance in determining contaminant levels in groundwater.

열처리에 따른 MWCNT/ZnO 복합체 필름 가스센서의 NOX 가스 검출 특성 (The Detection Characterization of NOX Gas Using the MWCNT/ZnO Composite Film Gas Sensors by Heat Treatment)

  • 김현수;장경욱
    • 한국전기전자재료학회논문지
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    • 제31권7호
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    • pp.521-526
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    • 2018
  • In particular, gas sensors require characteristics such as high speed, sensitivity, and selectivity. In this study, we fabricated a $NO_X$ gas sensor by using a multi-walled carbon nanotube (MWCNT)/zinc oxide (ZnO) composite film. The fabricated MWCNT/ZnO gas sensor was then treated by a $450^{\circ}C$ temperature process to increase its detection sensitivity for NOx gas. We compared the detection characteristics of a ZnO film gas sensor, MWCNT film gas sensor, and the MWCNT/ZnO composited film gas sensor with and without the heat-treatment process. The fabricated gas sensors were used to detect $NO_X$ gas at different concentrations. The gas sensor absorbed $NO_X$ gas molecules, exhibiting increased sensitivity. The sensitivity of the gas sensor was increased by increasing the gas concentration. Additionally, while changing the temperature inside the chamber for the MWCNT/ZnO composite film gas sensor, we obtained its sensitivity for detecting $NO_X$ gas. Compared with ZnO, the MWCNT film gas sensor is excellent for detecting $NO_X$ gas. From the experimental results, we confirmed the enhanced gas sensor sensing mechanism. The increased effect by electronic interaction between the MWCNT and ZnO films contributes to the improved sensor performance.

순환여과 양식시스템 내 무지개송어(Oncorhynchus mykiss)의 적정 용존산소 농도평가 (Evaluation of the optimal dissolved oxygen level for rainbow trout (Oncorhynchus mykiss) in the recirculating aquaculture system)

  • 박근홍;최진서;이영훈;박정환
    • 수산해양기술연구
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    • 제59권4호
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    • pp.387-398
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    • 2023
  • Conventional aquaculture faces declining productivity, shifting to recirculating aquaculture system (RAS), known for minimizing water usage and maintaining consistent water temperatures for year-round fish growth. Rainbow trout (Oncorhynchus mykiss), a globally important cold-water species and the third most farmed fish in inland waters of Korea, valued for its fecundity and rapid growth. Dissolved oxygen, an important environmental factor affecting fish production and economics, highlights the need for smart aquaculture practices. Since 2018, the rise of intelligent aquaculture platforms, incorporating information and communications technology (ICT), emphasizes the essential role of RAS implementation. This eight-week study aimed to determine the optimal dissolved oxygen concentration for rainbow trout in RAS, utilizing a device for continuous monitoring, control and record. Dissolved oxygen concentrations were set at 5-6 mg/L, 9-10 mg/L, 14-15 mg/L and 17-18 mg/L. The growth rate significantly decreased at 5-6 mg/L, with no significant differences in other experimental groups. In hematological analysis, growth hormone (GH) was significantly highest at 5-6 mg/L, followed by 9-10 mg/L while Insulin-like growth factor-1 (IGF-1) was significantly lowest at 5-6 mg/L. In conclusion, the optimal dissolved oxygen concentration for rainbow trout in RAS is approximately 9-10 mg/L. Higher concentrations do not contribute to further growth or profitability.

강제환기식 양돈시설의 암모니아 및 미세먼지 배출계수 산정 (Estimation of Particulate Matter and Ammonia Emission Factors for Mechanically-Ventilated Pig Houses)

  • 박진선;정한나;홍세운
    • 한국농공학회논문집
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    • 제62권6호
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    • pp.33-42
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    • 2020
  • Emission factors for ammonia and particulate matters (PMs) from livestock buildings are of increasing importance in view of the environmental protection. While the existing emission factors were determined based on the emission inventory of other countries, in situ measurement of emission factors is required to construct an accurate emission inventory for Korea. This study is to report measurements of ammonia and PMs emissions from mechanically-ventilated pig houses, which are common types of pig barns in Korea. Ventilation rates and concentrations of ammonia and PMs were measured at the ventilation outlets of a weaner unit, a growing pig unit and a fattening pig unit to calculated the emission factors. The PMs emission was characterized with different aerodynamic diameters (PM2.5, PM10, and total suspended particulates (TSP)). The measured ammonia emission factors for weaners, growing pigs and fattening pigs were 0.225, 0.869 and 1.679 kg animal-1 yr-1, respectively, showing linear increase with pigs' age. The PMs emission factors for three growing stages were 0.023, 0.237 and 0.241 kg animal-1 yr-1, respectively for TSP, 0.017, 0.072 and 0.223 kg animal-1 yr-1, respectively for PM10, and 0.011, 0.016 and 0.151 kg animal-1 yr-1, respectively for PM2.5. PMs emissions were increased with pigs' age due to increasing feed supply and animal movement. The measured emission factors were smaller than those of the existing emission inventory indicating that the existing ones overestimate the emissions from pig buildings and also suggesting that long-term in situ monitoring at various livestock buildings is required to construct the accurate emission inventory.

복합토지이용 유역의 수질 관리를 위한 미측정 용존유기탄소 농도 추정 (Development of Regression Models for Estimation of Unmeasured Dissolved Organic Carbon Concentrations in Mixed Land-use Watersheds)

  • 박민경;범진아;정민혁;정지연;윤광식
    • 한국물환경학회지
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    • 제39권2호
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    • pp.162-174
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    • 2023
  • In order to prevent water pollution caused by organic matter, Total Organic Carbon(TOC) has been adopted indicator and monitored. TOC can be divided into Dissolved Organic Carbon(DOC) and Particulate Organic Carbon(POC). POC is largely precipitated and removed during stream flow, which making DOC environmentally significant. However, there are lack of studies to define spatio-temporal distributions of DOC in stream affected by various land use. Therefore, it is necessary to estimate the past DOC concentration using other water quality indicators to evaluate status of watershed management. In this study, DOC was estimated by correlation and regression analysis using three different organic matter indicators monitored in mixed land-use watersheds. The results of correlation analysis showed that DOC has the highest correlation with TOC. Based on the results of the correlation analysis, the single- and multiple-regression models were developed using Biochemical Oxygen Demand(BOD), Chemical Oxygen Demand(COD), and TOC. The results of the prediction accuracy for three different regression models showed that the single-regression model with TOC was better than those of the other multiple-regression models. The trend analysis using extended average concentration DOC data shows that DOC tends to decrease reflecting watershed management. This study could contribute to assessment and management of organic water pollution in mixed land-use watershed by suggesting methods for assessment of unmeasured DOC concentration.

기계학습을 통한 토양오염물질 농도 예측 및 분포 매핑 (Predicting Concentrations of Soil Pollutants and Mapping Using Machine Learning Algorithms)

  • 강혜원;박상진;이동근
    • 환경영향평가
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    • 제31권4호
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    • pp.214-225
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    • 2022
  • 본 연구는 사업시행이 환경에 미치는 부정적 영향을 최소화할 수 있는 방안을 강구하기 위해 환경영향평가 토양 부문을 강조하였다. 영향평가 절차에 대한 일련의 노력으로서 도시개발사업을 대상으로 하는 국가 인벤토리 기반 데이터베이스를 구축하였으며, 세 가지 기계학습 모델 성능 평가 및 토양오염물질 농도분포 매핑을 진행하였다. 여기에서, 가장 우수한 성능을 보여준 Random Forest 모델을 사용하여 대한 민국 수도권 지역을 대상 9가지 토양오염물질을 매핑하였다. 본 연구의 결과는 도시화가 가장 활발한 서울지역에서 아연(Zn), 불소(F) 및 카드뮴(Cd) 농도가 상대적으로 우려되는 것을 발견하였다. 또한, 수은(Hg)과 크롬(Cr6+)의 경우 농도가 기준 이하로 검출되었는데, 이는 중금속 농도에 영향을 미치는 산업 및 공업단지와 같은 오염원 부족이 원인으로 도출되었다. 토양오염물질 공간분포 매핑을 통해 토양특성 및 토지이용 유형과 오염물질 간의 유의한 상관관계를 유추하였다. 이를 통해 사업 현장 위치에 관한 토양오염 최소화 및 계획 결정에 대한 효율적인 토양관리 방안을 구축할 수 있을 것으로 기대한다.

In situ reduction of gold nanoparticles in PDMS matrices and applications for large strain sensing

  • Ryu, Donghyeon;Loh, Kenneth J.;Ireland, Robert;Karimzada, Mohammad;Yaghmaie, Frank;Gusman, Andrea M.
    • Smart Structures and Systems
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    • 제8권5호
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    • pp.471-486
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    • 2011
  • Various types of strain sensors have been developed and widely used in the field for monitoring the mechanical deformation of structures. However, conventional strain sensors are not suited for measuring large strains associated with impact damage and local crack propagation. In addition, strain sensors are resistive-type transducers, which mean that the sensors require an external electrical or power source. In this study, a gold nanoparticle (GNP)-based polymer composite is proposed for large strain sensing. Fabrication of the composites relies on a novel and simple in situ GNP reduction technique that is performed directly within the elastomeric poly(dimethyl siloxane) (PDMS) matrix. First, the reducing and stabilizing capacities of PDMS constituents and mixtures are evaluated via visual observation, ultraviolet-visible (UV-Vis) spectroscopy, and transmission electron microscopy. The large strain sensing capacity of the GNP-PDMS thin film is then validated by correlating changes in thin film optical properties (e.g., maximum UV-Vis light absorption) with applied tensile strains. Also, the composite's strain sensing performance (e.g., sensitivity and sensing range) is also characterized with respect to gold chloride concentrations within the PDMS mixture.

Design of Optical Biological Sensor for Phycocyanin Parameters Measurement using Fluorescence Technique

  • Lee, Sung Hwa;Mariappan, Vinayagam;Won, Dong Chan;Ann, Myungsuk;Yang, Seungyoun
    • International journal of advanced smart convergence
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    • 제5권2호
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    • pp.73-79
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    • 2016
  • Remote sensing and measurement are of paramount importance of providing information on the state of water quality in water bodies. The formation and growth of cyanobacteria is of serious concern to in land aquatic life forms and human life. The main cause of water quality deterioration stems from anthropogenic induced eutrophication. The goal of this research to quantify and determine the spatial distribution of cyanobacteria concentration in the water using remote sensing technique. The standard approach to measure water quality based on the direct measurement of the fluorescence of the chlorophyll a in the living algal cells and the same approach used to detect the phycobilin pigments found in blue-green algae (a.k.a. cyanobacteria), phycocyanin and phycoerythrin. This paper propose the emerging sensor design to measure the water quality based on the optical analysis by fluorescence of the phycocyanin pigment. In this research, we developed an method to sense and quantify to derive phycocyanin intensity index for estimating cyanobacteria concentrations. The development of the index was based on the reflectance difference between visible light band 620nm and 665nm. As a result of research this paper presents, an optical biological sensor design information to measure the Phycocyanin parameters in water content.

Study on Solution-Processed Flexible Electrochromic Devices with Improved Coloration Efficiency and Stability

  • Gihwan Song;Haekyoung Kim
    • 한국전기전자재료학회논문지
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    • 제36권1호
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    • pp.1-9
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    • 2023
  • According to the recent global warming, it is necessary to use energy efficiently together with eco-friendly energy. The development of alternative technologies is requisite for managing the current energy and climate crises. In this regard, "smart windows," which can control solar radiation, can be used to mitigate energy demands. Electrochromic devices (ECDs) effectively control the amount of solar energy reaching commercial and other living areas and maintain climate conditions via color modulation in response to small external stimuli, such as temperature and light irradiation. However, the performance and the stability of ECDs depend on the state of the electrolyte and sealing of the device. To resolve the aforementioned issues, an ECD was manufactured by using a poly (methyl methacrylate) (PMMA)-based gel polymer electrolyte (GPE), and a laminating method was used to adequately seal the ECD. The concentrations of PMMA, acetonitrile (ACN), and ferrocene (Fc) were controlled to optimize the composition of the GPE to achieve an enhanced electrochromic performance. The fabricated GPE-based ECD afforded high optical contrast (~81.92%), with high electrochromic stability up to 10,000 cycles. Moreover, the lamination method employing the GPE could be used to fabricate large-area ECDs.