• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.102-108
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• 1996

연안매립 및 신항만 건설, 해안선 정비사업 등과 같은 대규모 공사는 인근 해역에서의 해수유동의 변화와 해수의 혼탁도 증가 및 퇴적물의 침식과 퇴적에 의한 해저 지형의 변형을 초래하고, 이로 인해 기존 항로의 매몰과 해양생물 생태계 변화 등과 같은 문제점을 유발한다는 것은 잘 알려진 사실이다. 특히 한국의 서해연안 대부분과 남해연안 일부에 분포되어 있는 미세-점착성 퇴적물은 사질성 퇴적물과는 달리 퇴적물에서 부유된 토사 입자의 침강 속도가 아주 작아서, 파랑과 조류 등과 같은 해수유동에서 의해 쉽게 이동되어 현저한 해저 지형의 변형을 초래한다. (중략)

• Journal of Environmental Science International
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• v.3 no.1
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• pp.49-56
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• 1994

Effect of the liquid circulation velocity on the biofilm development was investigated in an inverse fluidized bed biofilm reactor(IFBBR). To observe the effect of the influent COD concentration on biofilm simultaneously, the influent COD value was adjusted to 1000mg/1 f for 1st reactor, and 2500mg/l for 2nd reactor. The liquid circulation velocity was adjusted by controlling the initial liquid height. As the liquid circulation velocity was decreased, the settling amount of biomass was increased and the amount of effluent biomass was decreased. Since the friction of liquid was decreased by the decrease of liquid circulation velocity, the biofilm thickness was increased and the biofilm dry density was decreased. In the 1st reactor the SCOD removal efficiency was constant regardless of the variation of the liquid circulation velocity, but it was increased by the decrease of the liquid circulation velocity because of more biomass population in 2nd reactor.

• Journal of Pharmaceutical Investigation
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• v.15 no.2
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• pp.83-90
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• 1985

The effects and the optimum manufacturing conditions for the preparation of synthetic aluminum silicate which has acid-consuming power and adsorbing capacity were investigated. The results are as follows: 1. The adsorbing capacity was affected by the mixing order of the reactants, that is, the excellent ones were obtained by the method which add the sodium silicate solution to the potassium alum solution. 2. Even though preparing by the bane manufacturing condition, the acid-consuming power is superior to the adsorbing capacity. 3. According to the Box-Wilson Plan, the optimum reaction conditions are concentration of sodium silicate solution; 38% w/w, settling time; 43 hours at room temperature, drying time; 13 hours at $110^{\circ}C$.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.363-369
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• 2009

In order to evaluate primary clarifier performance on TSS(Total Suspended solids) removal, four different sampling sets were collected as part of this study; (1) weekly test, (2) the diurnal sampling, (3) the settling velocity distribution sampling. Primary effluent TSS($TSS_{PE}$) and non settleable TSS($TSS_{NON}$) concentrations were averaged 160 and 75.5 mg/L, respectively. These data suggest approximately 85 mg/L TSS can be removed more. Average $TSS_{NON}$, $TSS_{PE}$, and Dispersed TSS(DTSS) concentrations(75.5, 160, and 104 mg/L, respectively) suggest that 28.5 mg/L of TSS difference attributable to poor flocculation, whereas 56 mg/L of TSS difference attributable to poor hydraulics within primary clarifier. In this study, equations for maximum TSS removal efficiency and effluent TSS concentration were suggested and compared with experimented data.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.465-470
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• 2006

An experimental investigation is carried out to study 2-phase vertically upward hydraulic transport of solid particles by water and non-Newtonian fluids in a slim hole concentric annulus with rotation of the inner cylinder. Rheology of particulate suspensions in viscoelastic fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, etc. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Annular fluid velocities varied from 0.2 m/s to 3.0 m/s. Pressure drops and average flow rate and particle rising velocity are measured. For both water and 0.2% CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become.

• International journal of advanced smart convergence
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• v.9 no.1
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• pp.19-28
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• 2020

We studied the on-site treatment of soil contaminated by heavy metals and petroleum was tested using relocatable soil washing equipment for greater remediation efficiency. Different combinations of pH and solid/liquid ratio were tested to determine the optimum balance, settling on values of 5 and 1:2, respectively. Next, soils containing Pb, Hg, and petroleum were further tested to assess the optimum number of washing cycles. The remediation efficiency of Pb and Hg in soil contaminated solely by heavy metals was 90.1% and 86.4% after three and two washings, respectively. The remediation efficiency of petroleum in soil contaminated solely by petroleum was 98.8% after one washing. When soil contaminated by both heavy metals and petroleum was cleaned, up to 91.0% of Pb, 86.9% of Hg, and 96.1% of petroleum was removed after two, one, and one washings, respectively. We conducted all remediation efficiencies and concentration reductions satisfied the standard threshold for soil contamination in South Korea.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.3
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• pp.453-459
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• 1996

This study was carried out to determine the changes in quality during the drying process and the optimum drying condition for utilizing soybean curd residue. The quality criteria for soybean curd residue were acid value, peroxide value, fatty acid composition and microbial concentration. The acid values of soybean curd residue were 7.5, 4.5 and 5.9 KOH mg/g upon 12 hour drying with open-air sun, ambient-air blast and warm-air blast, respectively. The numbers of total aerobic bacteria and molds increased remarkably during drying with open-air sunlight, ambient-air blast and warm-air blast except for hot air blast. Among different drying methods, the hot air blast drying(1kg of sample) was the most effective methods, which completed in three hours. Also, the drying method demonstrated a typical drying curve ; settling down, constant rate drying and falling rate drying period were shown within one hour, from one and three hours and after three hours, respectively. Moreover, there was significant variation in the constant drying period for the quality of soybean curd residue.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.10a
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• pp.61-64
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• 1992

Recently, by the lack of fill material, the dredg and fill(hydraulic fill) method is commonly used in reclamation projects. Hydraulic fill method dredges the soil and send it with water through the transportation pipe to the site. The intial state of the hydraulic fill material is accordingly the mixture of water and soil skeleton which settles with time forming a new soil layer. The properties of new soil layer is governed the size of the soil skeleton, the flow velocity of mixing water, salt concentration, the distance from the discharge pipe outlet, and other dredging conditions when settling process occur. In this study, the effects of gradation of derdged soil on the deposition properties (with emphasis on the optimum spacing of the discharge pipes) was investigated by field test. It was found that the soft fine graind soil was forme at 350m from the discharge pipe outlet when the dredged material was classified as CL, while the soft fine grained soil was not formed even at the distance farther than 400m from the diacharge pipe outlet when the dredged material was classified as SM.

• 한국해양학회지
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• v.18 no.1
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• pp.21-28
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• 1983

A series of experiments was performed to increase and make our puantitive understanding of the entrainuent and settling processes of fine-grained sediments, which are of critical importance to construct a predictive model of sediment experiments were performed in an annular flume. A rotating top produced a turbulent flow which in turn exerted and are shown to be dependent on the sediment concentration and the presence of clay minerals. The parameters on which entrainment strongly depends were identified to be the shear stress, water content (time ofter deposition), and the type of sediment (grain size and mineralogy).

• Korean Journal of Ecology and Environment
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• v.44 no.1
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• pp.66-74
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• 2011

This numerical study aims to investigate the effect of cohesive sediment on turbulence structure due to density stratification. The transport model for cohesive sediment incorporated with flocculation model has been selected and calculates the concentration, fluid momentum, and turbulence. From the model results, it is known that suspension of sediment decreases turbulence intensity. It is also found that cohesive sediment has a relatively weak effect on turbulence damping compared to noncohesive sediment. The low settling velocity and more suspension of cohesive sediment are considered to be mechanisms of this behavior. Richardson number determined with results of this study quantitatively shows that cohesive sediment causes less stable density stratification condition and, as a result, the turbulence structure is less damped compared to the case of noncohesive sediment.