• 한국환경보건학회지
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• 제35권5호
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• pp.411-416
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• 2009

This study was initiated to improve the cooling water quality by chemical coagulation and sedimentation in steel mills. Due to the inefficient flocculation in the settling tanks of blast furnace cooling water systems, the solid particles in the cooling water overflow accumulate and clog the cooling system. To protect the cooling water system from such fouling, proper flocculants must be continuously used. Laboratory tests were performed for the indirect cooling water system of a plate mill. The batch test in the gas scrubbing cooling water system of a blast furnace showed that the proposed coagulant was more effective for the improvement of coagulation and sedimentation than the existing one. During the tests, cationic flocculants were more effective than use of only an anionic flocculant. The suggested combination of anionic and cationic flocculants can probably improve the turbidity removal efficiency of the cooling water. Proper control of the overflow rate by the designed residence time would help turbidity removal efficiency in the settling tank. In addition, the settling can be enhanced by adopting rapid and slow mixing alternatively. Scale problems in blast furnace cooling water system were reduced to some extent by efficient settling.

• 대한환경공학회지
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• 제28권6호
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• pp.677-686
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• 2006

본 연구의 목적은 기존 정수처리 공정에 하향류식 호기성 생물여과 공정을 설치하였을 때 적정 위치를 선정하고자, 응집/침전 전(Mode A)에 BAF 공정을 설치하였을 때와 응집/침전 후(Mode B)에 BAF 공정을 설치하였을 때의 부유성 입자물질, 유기물, 암모니아성 질소 제거효율을 비교하고자 하였다. 운전결과 입자성물질(turbidity, SS)의 제거효율은 모든 EBCT에 걸쳐 Mode A, B 모두 약 80% 정도의 효율을 보였으며 Mode A에서의 효율이 다소 높은 것으로 조사되었다. 유기물질($BOD_5$) 제거 및 질산화 효율도 90% 이상으로 나타났으며 Mode A에서 의 효율이 더 좋은 것으로 나타났다. 생물막 두께 및 양은 EBCT가 증가할수록 커졌으며, 기질이 유입되는 상부에서 하부에 비해 약 30% 이상 미생물량이 많았다. 비산소소비속도(SOUR)는 기질이 유입되는 반응기 상부, Mode A에서 증가하는 경향을 나타내었으며 약품주입량 비교 시 Mode A가 경제적인 것으로 나타났다. 기존상수처리공정과 Mode A에 대한 경제성 분석결과 연간 응집제를 67%, 염소주입량을 95% 가량 절감할 것으로 조사되었다.

• 한국산림과학회지
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• 제98권6호
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• pp.669-675
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• 2009

본 연구는 산림유역 개발이 하천 출구의 토사 퇴적에 미치는 영향을 규명하기 위해 토사 퇴적물에 함유된 세슘 농도를 분석하여 세슘총량과 토사 퇴적속도를 계산하였다. 세슘은 1954년 핵실험에 의해 최초 방출되었고, 토사의 입자에 흡착되어 퇴적하기 때문에 토사 퇴적물의 연대측정으로 이용되고 있다. 쿠시로습지유역의 대규모 산림은 1950년대 이후 농지로 개발되었고, 1954년 이후 하천 출구에서는 36~148 cm의 부유토사가 퇴적되었다. 세슘을 함유한 토사는 유역으로부터 유출되어 하천 출구에 퇴적하므로 하천 출구에서 세슘총량은 대조구보다 높은 값을 나타내었다. 또한 세슘총량은 토사 퇴적속도가 증가할수록 증가하였지만, 쿠쪼로강과 쿠시로강의 출구에서 세슘총량은 완만하게 증가하였다. 왜냐하면 쿠쪼로강과 쿠시로강에서 유로침식으로 발생한 토사는 세슘을 거의 포함하고 있지 않기 때문에 이들 하천 출구에서 토사퇴적은 증가하고 있었지만 세슘총량은 크게 증가하지 않았다.

• 상하수도학회지
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• 제18권2호
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• pp.222-227
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• 2004

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.

• 펄프종이기술
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• 제44권5호
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• pp.8-13
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• 2012

The flexography ink has disadvantage in a deinking process because it tends to form too fine particles in alkali condition to be removed in flotation deinking. The influence of pH conditions on the particle size of phthalocyanine cyan ink used for flexo-printing was investigated to see the effect of pH conditions on flexography ink dispersion. Flexography ink particles prepared by grinding dried ink films were used in this experiment. Greater reduction of the ink particle size was noticed under alkaline pH condition, which was attributed to dissolution of resin component of the ink. Adsorption behavior of flexography ink onto pigment particles was examined using clay and talc as substrate pigments. Pretreatment of inorganic pigments with a cationic poly-DADMAC increased the surface adsorption of flexography ink particles, which improved the removal of the inks by centrifugal sedimentation of inorganic pigments. Most efficient removal of the ink particles was achieved when an optimal addition level of the cationic polymer was used for pretreatment of inorganic pigments, and this optimal addition level corresponds to the surface saturation point of the polyelectrolyte. Adsorption of flexography ink particles onto inorganic pigments improved the ink removal in flotation deinking since the pigment particles has the optimal particle size for flotation deinking.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2006년도 춘계학술발표대회 및 제10회 신소재 심포지엄 논문개요집
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• pp.16.2-16.2
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• 2006

• 한국정보통신학회논문지
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• 제8권8호
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• pp.1732-1739
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• 2004

본 논문은 다량의 가변적인 정보를 보유하고 있는 수중에서 유동하는 입자의 움직임을 추적하고 유체의 흐름에 따라 분산되는 입자의 분산정도 그리고 입자의 침전패턴을 정확하게 예측해내기 위해 인공신경망 알고리즘을 도입한 가시화 시스템을 제안한다. 이러한 시스템은 물과 같은 공간에서 움직이는 다양한 입자들을 고려하고 있는데, 물의 흐름을 위해서 운동량방정식과 연속방정식을 일반화하여 흐름을 제어하고 있다. 또한 입자간에 작용하는 부력, 침강력 등의 물리적인 힘과 침전패턴에 주요한 영향을 주고 있는 입자간의 충돌은 인공신경망 ART2를 이용하여 충돌을 감지하도록 하고 있다. 본 논문에서 제안한 시스템을 통해 다양한 외부적인 요인에 따라 움직임을 달리하는 유동 입자들을 실제 물에서와 같이 유사하게 가시화되도록 한다. 또한 가시화된 유동 입자의 움직임을 효율적으로 추적하고, 침전하는 입자들의 패턴까지도 미리 예측해 낼 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.715-718
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• 2001

This study uses traditional alum coagulation and sedimentation process to treat CMP wastewater from cleaning after polishing. The primary goal is to successfully recycle both solid fines and water for semiconductor manufacturing. Results indicated that CMP wastewater may be successfully treated to recover clean water and fine particles by alum coagulation. The optimum operating conditions for coagulation are as fellowing: alum dosage of 10 ppm, pH at 5, rapid mixing speed at 800 rpm, 5 min rapid mixing time, and long slow mixing time. The treated water with low turbidity and an average residual aluminum ion concentration of 0.23 ppm may be considered for reuse. The settled sludge after alum coagulation contains mainly SiO$_2$particle with a minor content of aluminum (1.7 wt%) may be considered as raw materials for glass and ceramic industry.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1992년도 가을학술발표회 논문집
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• pp.65-68
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• 1992

In characterizing a suspension, heterogenety is included onto the previous characterization using solids concentrations and flocculent characteristics, because of its importance in hydrodynamics. The mechanism of interface formation during the sedimentation of concentrated suspension (thickening) is investigated from a microcosm consisting of four particles in a same plane and a smaller particle below. The critical distances after shich interface forms are calculated as a function of particle size ratio when the small particle is located in the middle of the squre datermined by the large particles. The results shows that the critical separation distance increase as the size ratio approaches to one (homogeneous suspension). This conforms to the trend of existing observations that homogeneous suspensions create the solid-liquid interface at much lower concentration (at al larger separation distance) that the heterogeneous suspensions.

• Journal of Korean Society for Atmospheric Environment
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• 제20권E2호
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• pp.61-68
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• 2004

Aerosol losses in a 100L Tedlar$^{(R)}$ bag were investigated for the aerosols with number median diameter of 0.05 ${\mu}{\textrm}{m}$ and number concentration of 6.4 ${\times}$ 10$^4$ cm$^{-3}$ . Over a 1 hr period, loss of particles in the bag is apparent, and the volume decrease with time is significant. The number concentration, surface area, and volume concentration of the aerosols decreased to 34, 50, and 52% of the initial value in 30 min, respectively. This indicates that deposition to the walls was the main loss process for aerosols in the Tedlar$^{(R)}$ bag. Theoretical calculations showed that coagulations and deposition by diffusion and gravitational sedimentation would not change aerosol characteristics significantly, and the electrical force was the dominant loss process for particles in the Tedlar$^{(R)}$ bag over a 1 hr period.eriod.