• KSBB Journal
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• v.9 no.5
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• pp.457-463
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• 1994

A new method that considers the pellet sedimentation characteristics for fungal cell concentration measurement was developed using optical density. Appropriate mixing of the pellet suspension almost homogeneously was tried to prevent the sedimentation of the pellet by a small magnetic bar in cuvette, giving a stable optical density. The linear relationship between optical density and the dry cell weight was obtained. However, different curved lines were observed according to the pellet size. Optical density couldn't be detectable in the size range of $355{\mu}m$above. It was concluded from the result that the use of optical density for measuring cell concentration in fungal broth became possible by considering the characteristics.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.667-670
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• 2009

수용액에 첨가된 나노다이아몬드는 용매상 내에서 안정된 분산 특성을 나타낸다. 이런 분산 특성은 일정 시간동안 유지되지만, 농도와 시간에 따라 분산특성이 떨어지면서 일부 다이아몬드들의 침강이 나타난다. 이런 분산 및 침강 특성을 정량화하기 위하여 나노다이몬드 수용액의 흡광특성을 비교 분석하였다. 파장에 따른 나노다이아몬드의 흡광도는 농도에 상관없이 350 nm까지 상승하다가 점차적으로 완만하게 감소하고 있다. 또한 300nm 파장에 대한 흡광도는 나노다이아몬드의 농도에 따라 거의 직선적으로 증가하는 것으로 나타났다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.169-169
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• 2015

유사 입자의 크기는 유사의 특성 및 그에 따른 거동 변화에 중요한 영향을 미친다. Stokes 침강 속도 모형에서 유사의 침강 속도에 가장 많은 영향을 주는 인자는 유사의 크기인 것 또한 확인된다. 유사 입자의 크기가 약 $60{\mu}m$보다 작은 유사들은 알갱이 사이의 점착력을 무시할 수 없다. 이로 인해 유사들은 응집 현상을 겪으며 입자 본래의 크기보다 크기가 큰 플럭을 형성하는 점착성 유사로 분류된다. 응집 현상이란, 흐름 내 점착성을 띠는 일차입자(Primary Particle)가 응집과 파괴를 반복하며 플럭을 형성하는 현상을 뜻한다. 입자 간의 충돌을 통해 응집이 진행되며 난류 전단으로 인해 형성된 플럭의 파괴가 발생한다. 많은 연구에서 점착성 유사의 충돌을 야기하는 가장 지배적인 원리는 난류라 알려져 있다. 이러한 응집 현상으로 인하여 플럭의 크기와 밀도는 지속적으로 변화를 겪으며 비점착성 유사와 다른 특징들을 보인다. 흐름에 존재하는 유사의 이동은 이송-확산 방정식을 통해 표현된다. 이송-확산 방정식은 시간 변화에 따른 농도의 변화를 입자의 침강과 난류 및 유사 자체의 특징에 의한 확산으로 해석한다. 침강속도로 대변되는 이송과 달리, 확산은 난류흐름 내에서 유사가 확산되는 정도를 정량화하기 위한 인자가 요구된다. 난류에 의한 유사의 확산은 유사 자체 특성에 따른 물질 확산에 비하여 매우 큰 값을 가지며, 이를 확산 계수로 개념화 한다. 확산계수는 와점성계수와 Schmidt 수(${\sigma}_c$)의 비로 정의된다. ${\sigma}_c$는 난류의 점성과 난류로 인한 부유과정에 의해 유사가 확산되는 정도를 나타낸다. 이에 따라 ${\sigma}_c$의 변화가 유사의 부유 및 침강거동에 많은 영향을 미칠 것이라 판단되나, 국내외에서 수행된 연구 동향에서는 ${\sigma}_c$를 0.5부터 1.0 사이의 상수를 적용하여 수행되었다. 이에 본 연구에서는 ${\sigma}_c$의 크기에 따라 달라지는 유사의 부유 및 침강 변화에 의한 총 부유량을 살펴보고자 한다. 유사의 점착성을 고려할 수 있는 1DV 수치 모형을 이용하여 비점착성 유사와 점착성 유사를 대상으로 수치연구를 수행하며, 유사의 크기 및 ${\sigma}_c$의 변화에 따른 총 부유량 경향을 살펴본다. 그 결과, 점착성 유사는 ${\sigma}_c$의 증가에 따라서 유사의 총 부유량이 증가하는 현상이 나타난 반면 비점착성 유사는 ${\sigma}_c$의 증가에 따라 유사의 총 부유량이 감소하는 경향이 나타났다. 그러나 크기가 아주 작은 비점착성 유사를 대상으로 수치 연구를 수행한 결과, ??에 따른 총 부유량의 경향은 유사의 점착성에서 기인하는 것이 아닌 입자의 크기로부터 야기되는 특성이라는 결론이 도출되었다.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.10a
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• pp.277-284
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• 1996

• Journal of Industrial Technology
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• v.20 no.A
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• pp.113-122
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• 2000

Column tests in the laboratory were preformed to investigate characteristics of settling process of dredged soil sampled from in-situ. Test results were analyzed by using the existing theories on discrete settling and hindered settling. From column tests of monitoring the interface with time, settling was found to be a linear process with time and the settling rate was increased with initial water content of slurry. The settling rate was also observed to decrease with increasing initial height of slurry. Most of settling process were composed of flocculation, hindered settling and self-weight consolidation. On the other hands, flocculation of soil during settling was observed and it was found that the size and density of flocculated particles could be analyzed by using the method proposed by Richardson and Zaki.

• Journal of Ocean Engineering and Technology
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• v.12 no.2 s.28
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• pp.111-120
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• 1998

Laboratory settling experiments (column, recirculating flume) were conducted for further understanding of the physical processes of cohesive sediment transport. \In still water experiments, the growth rate of flocculation is dependent upon the initial suspended concentration. Consequently, the settling velocity increases with concentration of flees. In flocculation settling regime, the exponent n in the settling velocity, $w_s=kC^n$, for Nakdong estuary mud was obtained empirically. The exponents were found to be 1.33, and 1.06 for the initial suspended concentrations of 1 g/i and 3 g/t, respectively. In flowing water, experiments for the median settling velocity with Nakdong mud in a recirculating flume were conducted. Settling velocity was found to depend much more strongly on the current velocity than initial concentrations. The temporal variation of suspended concentration increases as current velocity decreases.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.4
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• pp.345-352
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• 1989

The immunochemical property of lectin in soybean and the presence of lectin in seeds of six soybean cultivars were investigated by immunochemical methods. All seeds of six soybean cultivars formed one precipitin line against the soybean lectin antibody and showed immunochemically homologous precipitin pattern among the cultivars in immunodouble diffusion test. Four antigenic components in soybean lectin were detected by the crossed imuno-electrophoresis of a soybean seed antigen against the soybean lectin antibody. Cultivar, Jangyeop-kong contained the highest amount of lectin and the next were Kwangkyo, Hwangkeumkong, Baegunkong, and Jangbaegkong or Paldal-kong in order of lectin content. The lectin purified from the seeds of six soybean cultivars agglutinated rabbit erythrocytes, but did not agglutinate the fungal spores which were Fusarium sp., Alternaria sp., Cuvalaria sp., and Colletotrichum sp. isolated from the infected seeds or leaves of soybean.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.20-26
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• 2008

The primary purpose of this study was to quantitatively examine whether there was a difference in the settling velocities of cohesive sediments in the Saemankeum artificial lake before and after the closure of the Saemankeum seadike. Through in situ sediment sampling and laboratory experiments, the settling velocities were estimated as a function of the suspension concentration and their physico-chemical properties, such as grain size distribution, the percentage of organic contents, mineralogical composition, etc. were also examined. In this study, their inter-relation with settling velocities were also analyzed qualitatively. The result of the settling tests for Saemankeum sediments showed that there was a big difference in the settling velocities before and after the closure of the Saemankeum seadike. Its settling velocities in a flocculated settling region became remarkably larger after the closure compared to those before the closure, while they were similar but relatively smaller in a hindered settling region. This was found to be mainly due to the difference in their grain size.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.3
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• pp.122-130
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• 2013

To examine floc characteristics of cohesive bed sediment of the Yeongsan River estuary, a floc camera system has been developed and utilized to observe flocs under varying conditions. In order to validate the floc camera system, sand particles were passed through 88-125 and $63-88{\mu}m$ sieves and observed within the laboratory. Mean grain size and settling velocities were found to be 102 and $56.2{\mu}m$ and 6.7 and 5.9 mm/s, respectively. Artifacts of particles estimated outside of the sieve range are attributed to being imaged out of the depth of focus. However, as mean grain size and settling velocity of each size class were within the confidence interval, the floc camera system was confidently used to examine cohesive bed sediments of Yeongsan River estuary. The bed sediment sample was prepared with a concentration of 0.1 g/L in 0 psu deionized water. The mean grain size, settling velocity and fractal dimension of flocs were $40.6{\pm}0.66{\mu}m$, 14 mm/s, and 2.86, respectively. Experiments were also conducted using different salinities (10 and 34 psu) and sediment concentrations (0.1 and 0.3 g/L). Despite changing these parameters, the mean observed grain size and settling velocities were found to be the same within the error range of the system. The relatively higher values of settling velocity and fractal dimension are considered a result of the sediment containing relatively small concentrations of organic matter. Moreover, consistent floc size over various grain sizes and concentrations may be the result of insufficient turbulence to aggregate flocs.

• 지반과기술
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• v.8 no.3
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• pp.43-49
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• 2011