• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.13-24
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• 1988

This paper is concentrated on the development of oxygen transfer system by U-tube deep shaft in biological fluidised bed process. The depth of the shaft is 32 m, it is composed of downcomer and riser. Not only flow pattern and oxygen transfer in the deep shaft but also oxygen limitation in biofilm and oxygen utilization in biological fluidised bed are investigated. In this investigation, driving force for liquid circulation in the deep shaft is affected by air injection depth and gas hold-up in downcomer. Flow pattern of the deep shaft is revealed to plug flow. When flow velocity in the deep shaft is maintained to 0.52 m/sec, $K_La$ value is peak at 25~30 m depth in riser. The efficiency of dissolved oxygen supply which passed from the deep shaft to biological fluidised bed is estimated to 56~81 % in the organic wastewater treatment using the deep shaft and when dissolved oxygen concentration is 9.2 mg/l and over, limiting factors of flux and substrate within biofilm are organic materials. Terefore, organic loadings could be increase without decreasing of BOD removal efficiency.

• Journal of the Korean association of regional geographers
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• v.16 no.2
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• pp.100-109
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• 2010

The study examines two different sites to analyze the difference of stream channel profile between two different landuse areas on Neponset River, Boston, MA. Landuse represents the current status of land in terms of human, agricultural or forest, industry and environmental activity types. According to the previous research, forest and urban area are significantly distinguished in chemical characteristic, shape and bed load of the stream. On the chosen sites, I look at the cross-section profile, the slope, velocity, and roughness of the channels. With the data collected at the site I determined the value for the channel bed material using Manning's equation, and compared with the result of HEC-RAS model with the cross-section profile data I measured. In the forest area, water surface elevation and bed material obtained through Manning's equation are very close to HEC-RAS model result. However, in the resident area the Manning's 'n' value calculated much higher than assumption which was considered as cobble whose 'n' value is 0.03-0.06. The difference could be caused by unusual steep elevation on the site and the dam present down further. With the steep elevation upside of dam, there is critical-depth condition occurs. The difference of Manning's 'n' value reflects the difference of depth. HEC-RAS model was run to analyze the difference and the result shows that depth is 0.36 much less than 0.688 what I computed when the Manning's n value is 0.03(cobble) instead of the result of the study (0.13292). Beside, dam is a major source of fragmentation and degradation of stream, and it's possibly inferred upstream water levels are increased and stream velocity is decreased. This study is meaningful for introduction of HEC-RAS in geography field to analyze different sites with channel bed material, and it is going to be used more actively to manage river and river side.

• Journal of Animal Environmental Science
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• v.1 no.2
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• pp.117-124
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• 1995

This study was carried out to investigate the effect of depth of sawdust bedding and ground material in dairy cattle barn. Treatment included the concrete floor with a 10cm or 30cm sawdust and the earth floor with a 30cm sawdust. Eighteen cows were assigned to 3 pens with 16.5㎥/head bedding area. The results obtained were as follows : 1. The temperature of sawdust bed was highest in the earth floor with 30cm sawdust, and the moisture content of sawdust bed was highest in the concrete floor with 10cm sawdust bed. 2. Cows defecate feces 9.2, 8.7 and 9.3 times a day in 10cm sawdust on concrete floor(10S+C), 30cm sawdust on concrete floor(30S+C) and 30cm sawdust on non concrete floor(30S+ NC) respectively. In average, they excreta 9.1 times/day(85.8%) in the sawdust beds and 1.5 times/day(14.2%) in the feeding alley. 3. The ratio of daily water amount deposited vapor to total water amount deposited in sawdust beds was 74.0%, 61.5% and 47.1% in 10S+C, 30S+C and 30S+NC respectively. 4. N.P.K contents in the sawdust beds were higher for 10S+C compared with other treatments. 5. When 30cm of sawdust was applied on the earth ground NO$_3$-N contents in the sawdust bed was 37.7, 14.1 and 15.0ppm in depth of 30, 60 and 90cm under the ground, respectively, indicating some possibility of water pollution.

• Korean Journal of Remote Sensing
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• v.36 no.2_1
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• pp.103-119
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• 2020

Recently, the rapid redeposition and erosion of rivers artificially created by climate change and the Four Rivers Restoration Project is questionable. According to the revised law in Korea, the river management agency will periodically carry out bed changes surveys. However, there are technical limitations in contrast to the trend of increasing spatial coverage, density and narrowing of intervals. National organizations are interest in developing innovative bed changessurvey techniquesfor efficiency. Core of bathymetry survey is to measure the depth of rivers under a variety of river conditions, but that is relatively more risky, time-consuming and expensive compared to conventional ground surveys. To overcome the limitations of traditional technology, echo sounder, which has been mainly used for ocean depth surveying, has been applied to rivers. However, due to various technical limitations, it is still difficult to periodically investigate a wide range of areas. Therefore, technique using the remote sensing has been spotlighted as an alternative, especially showing the possibility of depth measurement using spectral characteristics. In this study, we develop and examine a technique that can measure depth of water using reflectance from spectral characteristics. As a result of applying the technique proposed in thisstudy, it was confirmed that the measured depth and the correlation and error corresponding to 0.986 and 0.053 m were measured in the depth range within 0.95 m. In the future, this study could be applied to the measurement of spatial depth if it is applied to the hyperspectral sensor mounted on the drone.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.1
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• pp.26-33
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• 1992

Physical experiments were conducted to investigate the suspension properties of silty mud in combined wave-current flow. Suspension mass when there was opposing current was much higher than that when there was following current. It is due to the fact which strong turbulent flow in the bottom is developed in the opposing current but oscillatory flow effect decreases in the following current. Critical bed shear stress for suspension of silty mud in combined wave-current flow was deduced to be $\tau$$_{c}$～0.045 N/$m^2$. Formulas expressing the relation with initial suspension rate with bed shear stress, and the relation between the former and measured significant wave height were deduced. The relationship of initial suspension rate with bed shear stress was significantly scattered, but the relationship with measured significant wave height was reasonably good. When there is wave only, vertical diffusion coefficients of sediment were calculated from the vertical concentration gradients of suspended sediment when the concentration of suspended sediment approached to nearly equilibrium state. The diffusion coefficient increased exponentially with height from the bottom in the lower half of the flow depth but were nearly constant in the upper half of the flow depth.h.

• Archives of Plastic Surgery
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• v.45 no.6
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• pp.564-571
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• 2018

Background Chronic wounds occur due to failure of the normal healing process, associated with a lack of deposition of cellular components and a suitable microenvironment such as the extracellular matrix (ECM). Acellular dermal matrix (ADM) is viewed as an ECM substitute, and a paste-type ADM has recently been introduced. We hypothesized that CGPaste, an injectable paste-type ADM, could serve as a scaffold and promote wound healing. Methods We retrospectively studied seven patients in whom CGPaste was applied between 2017 and 2018, who had pressure ulcers, necrotizing fasciitis, diabetic foot ulcers, traumatic defects, and osteomyelitis. The goal of applying CGPaste was to achieve complete wound healing with re-epithelialization or growth of granulation tissue, depending upon the wound bed status. CGPaste was injected based on the wound size along with the application of a dressing. Results Four of the seven patients showed granulation tissue on their wound bed, while the other three patients had a bony wound bed. The mean wound area was $453.57mm^2$ and the depth was 10.71 mm. Wound healing occurred in five of the seven patients (71.43%). The mean duration of complete healing was 2.4 weeks. Two patients showed failure due to paste absorption (29.57%); these patients had wound beds comprising bone with relatively large and deep wounds ($40{\times}30$ and $30{\times}20mm^2$ in area and 15 and 10 mm in depth). Conclusions CGPaste is an effective option for coverage of small and deep chronic wounds for which a flap operation or skin grafting is unfeasible.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.3
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• pp.179-188
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• 2006

The purpose of this study is to quantitatively estimate the settling and erosional properties for cohesive sediments in Shihwa lake. Settling tests are conducted by multi-depth method using a specially designed 1.8 m tall settling column, and erosion tests are conducted with annular flume under the uniform bed condition. As result of settling tests, it is confirmed that the settling velocity of the cohesive sediments has the range of $0.002 for suspended sediments concentration of 0.1$0.19{\sim}0.55N/m^{2}$ for bed shear stress of $1.14{\sim}1.32g/cm^{3}$, and the erosion rate coefficient decreases with logarithmic function in a range of $18.4{\sim}3.9mg/cm^{2}{\cdot}hr$ with increase of bed shear stress.

• Journal of Korea Water Resources Association
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• v.46 no.1
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• pp.25-34
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• 2013

In this study, the development processes of multiple bars in the channels with erodible banks were investigated by double Fourier analysis. The initially straight channels in the experiment flume were widened with eroding the side banks, and the multiple bars were generated and grew due to stalling of the sediment on the bed. The bars migrated downstream and the size of the bars increased with time. The flow was separated around the bars, and the bed and banks near the bars were scoured due to the impinged secondary flow. The morphologic changes were accelerated by the bank erosion, which affected the fluctuations of sediment discharge downstream. The double Fourier analysis of the bed waves showed that 1-1 mode (alternate bar) was dominant at the initial stage of the channel development. As time increased, 2-3 mode (central or multiple bars) was dominant due to the increased width to depth ratio. Moreover, the number of bars in a cross section of the channel were increased due to the non linearity of alternate bars. The width to depth ratio was increased by the bank erosion, which affected the bar migration and the bar wavelength. However, the dimensionless tractive force was decreased by it.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.385-395
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• 2011

The adjustment processes and responses of a series of mining pits by sand or gravel mining were investigated by laboratory experiments. The filling processes of the two pits were affected by the bars developed in the upstream of the channel. However, the bars were not developed and the bed was degradated in the downstream of the pits due to little sediment flow, which was trapped in the pits. The submerged angle of repose in the pits was nearly constant when the pits were being filled. After the filling processes of the pits were finished, the pit was speedily filled with sediment, and the bed was aggradated and migrated with speed. However, the angle of repose decreased. As the distance between the upstream pit and the downstream pit increased, the bed of the pit downstream was tailcutted and degradated. The migration speed of the pit decreased. However, the dimensionless pit depth increased as the distance between the pits increased. The dimensionless pit depth increased with time.

• Horticultural Science & Technology
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• v.18 no.6
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• pp.787-791
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• 2000

Lettuce seedlings used in this investigation of planting distance and labor-saving efficiency were first grown in 100-hole paper trays for 30 days. Seedling height for transplanting ranged from 3 cm to 6 cm and plants had 3 to 5 leaves. The beds prepared for transplanting were of the arched type and were 35-40 cm in width, 15-20 cm in bed height, and between-bed furrow width was 20 30 cm. Typical seedling planting depth with the transplanter was 4-5 cm, although depth was quite variable because of the irregularities of the ground. Total transplanting time with the transplanter varied from 2.6 to 2.7 hours per 10a, while it took 38.1 hours per 10a with conventional planting. It was critical that the condition of both the seedlings and the bed be adjusted to the transplanter before planting. Considering yield and inter-plant distance, optimal transplanter performance resulted with $60{\times}20cm$ or $60{\times}25cm$spacing, and the labor-saving efficiency using the transplanter was improved by over 93% of that of conventional planting by hand.