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        DAF에서 압력에 따른 미세기포의 크기특성

        한무영,박용효,이준,심재수 대한상하수도학회 2002 상하수도학회지 Vol.16 No.2

        Although DAF (Dissolved Air Rotation) has been successfully accepted for water and wastewater treatment, the fundamental characteristics of the process have not been fully investigated. According to recent theoretical work on DAF, bubble size is one of the most important factors that affect the DAF efficiency. It is well known that the size of bubbles in DAF is mostly affected by applied pressure. In this study, a newly developed Particle Counter Method (PCM) is introduced and compared with image analysis and verified. Using this PCM, the size of bubbles in DAF is measured under various pressure conditions from 2-6atm. Through a set of experiments, it was found that bubble size decreases as the pressure increases up to 3.5atm. This is a critical pressure after which bubble size does not decrease. According to the experimental results, it is not only costly but also unnecessary to maintain pressure more than 3.5atm if the goal is only to generate smaller bubbles for better removal efficiency in DAF operational practice.

      • 응집공정 개선을 위한 Streaming Current Detector(SCD)의 적용

        한무영,유재오,한정철 경희대학교 산학협력기술연구원 1996 산학협력기술연구논문집 Vol.2 No.-

        The determination of an optimal and economical coagulant dosage is a crucial problem in water treatment plants: low dosage generally yields a poor removal of raw water turbidity, whereas high dosage leads to sludges which are difficult to dewater. Existing dosage control methods such as jar test, computer controlled equation, zeta potential measurement have shown some limitations in the control of coagulation process. Recent trend of dosage control technology in the developed country is the use of SCD(Streaming Current Detector). SCD is an equipment which continuosely detects the surface charge of particles which are subject to vary with the addition of coagulant. In this study, a technique using SCD is tested and evaluated for the possible control of coagulation process in a water treatment plant. In a bench scale test, the method using jar test is compared with SCD method. Some advantages and disadvantages of SCD are discussed and sensitivity of SCD reading to several water quality parameters is examined. In a pilot scale test using a rapid mixing unit, both SCD and zeta meter reading are measured and compared. Both readings gave similar trends as the coagulant dosage, however, SCD is proven to be more useful because it can be measured on-line. Finally, in a full scale test, SCD is measured at an operating water treatment plant. SCD has the capability of detecting the variation of water quality as well as some problems resulting from clogging of sensors. Overall, SCD technique is proven to be useful and to give some scientifically sound basis for optimum coagulant control in a water treatment plant.

      • KCI등재

        Particle Counter를 이용한 정수장 응집공정의 진단 및 개선

        한무영 한국수처리기술연구회 2002 한국수처리학회지 Vol.10 No.3

        The goal of the flocculation process is to change the particle size distribution to best suit the subsequent processes. Although several methods exist to evaluate the flocculation process, no single universally accepted method has yet to be developed. The purpose of this paper is to present experiences whereby particle counting was used in the diagnosis and optimization of the flocculation process. The evaluation is based on particle dynamics, i.e., the change of the number of small and large particles. Some design deficiencies in the distribution channel and flocculation process have been identified from this method, and thus some operational parameters are suggested for optimum performance. The effects of changed design and equipment in flocculation process have been evaluated by comparing the particle counts at the existing design with particle counts after modification. Because the optimum condition may be site-specific, the method presented in this paper will be beneficial in the evaluation olf the flocculation process at other water treatment plants.

      • KCI등재

        屋上綠化가 빗물流出量 및 水質에 미치는 影響

        한무영,김준규,박상철 대한건축학회 2003 대한건축학회논문집 Vol.19 No.11

        Greening roof is gaining much interest as means for reduction of heat island effect and prevention of urban flooding. However, the effect of Greening roof on the quantity and quality of runoff has not been addressed simultaneously. In this study, the characteristics of rainfall runoff is investigated by a set of pilot plants with different depths of soil in order to investigate the effect of greening roof on the runoff characteristics and runoff water quality. Greening roof had reduction of rainfall runoff about 23~95 % at the 10 cm of depth of soil and about 24~100% at the 20 cm of depth of soil. Also, greening roof could decrease runoff of rainfall about 84~91 % of total quantity of rainfall during experimental period. However, greening roof gives much impact to the water quality. Filtrate of greening roof has been neutralized (pH 7~7.5) from acidic (pH 4~5). However, electro conductivity and turbidity of greening roof slightly increased. Overall, the greening roof has a good potential to reduce and delay the runoff peak flow. The quality of runoff from greening roof is good enough to be used for non drinking purpose.

      • KCI등재

        부상공정에서 금속이온의 기포 표면 전위 특성 및 반응효율

        한무영,독고석,김영환 대한상하수도학회 2004 상하수도학회지 Vol.18 No.2

        Flotation processes involve the use of very small bubbles(micro-bubbles) to separate particles from water. The process has become a good alternative to sedimentation, especially where the particles are small or of low density. Although the flotation process commences with a collision between particles and bubbles, most research has been focused only on the characteristics of the particles. In this paper, recent theoretical and experimental research on the characteristics of bubbles is summarized. The effect on the collision efficiency of the size and charge of bubbles is calculated through trajectory analysis. The size and charge of bubbles are measured under different conditions and the ramifications of the results are discussed. The results may lead to a better understanding and optimization of the existing process. In particular, we discuss an idea that a new advanced flotation process might be possible by the modification of the characteristics of the bubble alone or of both bubble and particle.

      • KCI등재

        건물의 지붕 집수면이 유출빗물의 수질에 미치는 영향

        한무영,이일용,박상철 대한상하수도학회 2003 상하수도학회지 Vol.17 No.3

        In order to investigate the effect of rooftop on the catchment of runoff and the possibility of using rainwater for non-drinking purpose, the water quality of rainfall and runoff were measured at a building in Seoul. This study shows the main contaminant source of roof runoff was rooftop when water quality of precipitation and roof runoff from the building were compared. The pH, turbidity, EC, metal ions and ions (anions and cations) of roof runoff increase through concrete rooftop during rainfall. However, the water quality of runoff in general is so good that they are acceptable to be used for toilet flushing, gardening, and car-washing without particular water treatments. This investigation concludes that rooftop is the essential part of rainwater systems as catchment area as well as the main contaminant source. And the water quality of rooftop runoff is suitable for non-drinking purpose. This study recommends the materials of catchment area should carefully selected and maintenance of rooftop be essential for rainwater harvesting.

      • KCI등재
      • KCI등재
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