• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.76-84
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• 2002

On-line conversion estimation of enzymatic esterification reactions in solvent-free media was investigated. In principle, conversion to ester can be determined from the amount of water produced by the reaction, because water is formed as a by-product in a stoichiometric manner. In this study, we estimated the water production rate only from some measurements of relative humidity and water balances without using any analytical methods. In order to test the performance of the on-line conversion estimation, the lipase-catalyzed esterification of n-capric acid and n-decal alcohol in solvent-free media was performed whilst controlling water activity at various values. The reaction conversions estimated on-line were similar to those determined by offline gas chromatographic analysis. However, when the water activity was controlled at higher values, discrepancies between the estimated conversion values and the measured values became significant. The deviation was found to be due to the inaccurate measurement of the water content in the reaction medium during the initial stages of the reaction. Using a digital filter, we were able to improve the accuracy of the on-line conversion estimation method considerably. Despite the simplicity of this method, the on-line estimated conversions were in good agreement with the off-line measured values.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.209-212
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• 2006

Line heating with water cooling is generally adapted process in the shipyards for the forming hull surface. The purpose of this paper is to develop a model of thermal deformation in water cooling process after the line heating. In order to simulate the cooling process, heat transfer analysis was performed by assuming the effects of water cooling as a negative heat-source. Experiment for the line heating with water cooling was performed for 9 models of plates in order to verify the cooling model. By using the suggested model for the water cooling process, it could be observed that the present method predict the plate deformations in the line heating more accurately.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.522-528
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• 2004

Microfiltration with in-line rapid coagulation for drinking water production was examined. The in-line rapid coagulation was conducted using newly developed mixing device instantaneous flash mixer. The flux decline during membrane filtration was monitored with coagulant dosage varied. Flux decline was minimized at 1.1mg/L of coagulant dosage, where streaming potential of coagulated water was near zero. The optimum dosage for the process control was explained by dimensionless distance (${\kappa}{\times}a$) of particle pairs, obtained from electrophoresis parameter describing electrostatic repulsion relative to Van der Waals energy between particle pairs in the pre-coagulated water.

• Environmental Engineering Research
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• v.24 no.1
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• pp.17-23
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• 2019

This study monitored changes in the level of heterotrophic bacteria in the filtrate and investigated the effect of stagnant water on it, using a batch-operated, gravity-driven membrane system for household water treatment. The filtration test was carried out in the presence and absence of stagnant water in the filtrate line. The results showed that stagnant water accelerated the heterotrophic bacteria levels, measured by heterotrophic plate count, even though the heterotrophic plate count of the filtrate finally increased up to $10^5CFU/mL$ regardless of the presence of stagnant water. When the change in heterotrophic plate count of a batch was monitored over filtration time, heterotrophic plate count of the filtrate rapidly decreased within 5 min for each batch filtration. Biofilm formation on the filtrate line was observed in the presence of stagnant water. The biofilm fully covered the filtrate line and contained numerous microorganisms. During storage after filtration, heterotrophic plate count increased exponentially. To improve the filtrate quality of a filtration-based household water treatment system, therefore, the stagnant water in the filtrate line should be minimized, the filtrate produced at the first 5 min is recommended not to be used as potable water, and the storage of filtrate should be avoided.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.12
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• pp.1335-1340
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• 2013

Herein the water film was introduced to the hydrophilic area on the line patterned surface to solve the contradiction caused by surface roughness (high different wettability has advantage to control the droplet but high roughness for that high wettability difference causes obstruction of droplet moving). Thus the droplet on the water film could not be hindered to line direction but restricted to orthogonal direction, effectively. In addition, droplet behaviors according to droplet volume and line thickness were studied. Droplet fell off the line with narrowing the interface between the droplet and the water film on the line. When the droplet fell off the line, the plate angle was designated as a critical plate angle and it used as an indicator of surface capability to control the droplet. As a result critical plate angle increases as droplet volume decreases and line thickness increases.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.1
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• pp.17-23
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• 1982

The corrosion loss of the shell plates and the bulkead plates of the oil tankers, nationalities of which belong to korea are determined and analyzed. The thickness of the plates are determined by use of the ultrasonic thickness meters at the check points set along the fore and aft line and the perpendicular to it. Difference between the original thickness and the determined one are given as the corrosion loss at the present age. 1. On the shell plates (1) The total mean of the corrosion loss shows the greatest value on the load water line in every age classes of the vessels. (2) The total mean of the corrosion loss on the fore and aft line shows little difference, even though it is slightly greater at the fore part, in every age classes of the vessels. (3) The corrosion loss along the perpendicular grows greater in the order of upper bilge line, light water line, freeboard line and load water line at 16 ages of the vessels, and the loss changes in the order of light water line, upper bilge line, freeboard line and load water line at 20 ages of the vessels. (4) The total mean of the corrosion loss along the light water line and upper and lower water line shows the greatest value on the fore part. That along the freeboard line and the load water line shows the greatest value on the midship part and on the after part, respectively. 2. On the bulkhead plates (1) The total mean of the corrosion loss shows the greatest value on the top part at the every age classes of the vessels. (2)The corrosion loss along the perpendicular grows greater in the order of the lower, center and upper part at every age classes of the vessels. (3) The total mean of the corrosion loss at the top part grows greater in the order of the transverse bulkhead of the side oil tank, that of center oil tank, longitudinal bulkhead of center oil tank, and transverse bulkhead of side water tank at the 20 ages of the vessels.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.3
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• pp.57-69
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• 2011

This study examined the relationship between Phragmites australis' growth and sediment properties at mud tidal flat of Donggum-ri, Gilsang-myeon, Gangwha-gun, Incheon city. Field survey was carried out from May, 2010 to October, 2010. Water content, soil texture, electric conductivity and water table depth for sediment, density, height, dry weight and flowering for P. australis were examined at several plots from the starting point (the coastal embankment) to the end point of the two populations. The result was as follows. Firstly, the water table increased along distance from the embankment at one line (N-line) but was similar at the other line (S-line) in a P. asustralis population. Water tables were higher out of than within a P. australis population at two populations. Secondary, in N-line, the height and dry weight of P. australis decreased along the distance from embankment but, in S-line, those were similar in its population. P. australis' growth was dependent on electric conductivity at lower layer (water table level) rather than upper one (the surface). Thirdly, density of P. australis changed during growing season and was similar in a population, except for the end point of patch. In summary, the growth and distribution of P. australis were dependent on salt content of tidal flat's sediment (water table level) and this was affected by fresh water of the inland.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.119-124
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• 2004

A water hammer mostly comes out when a valve fixed at the downstream end of the pipe-line system is rapidly closed or opened. A simple phenomenon of water hammer is often caused around us, and this phenomenon imperils the pipe systems occasionally. In this paper, we confirmed the phenomenon of water hammer by an experiment and forecasted a change of pressure in the pipe-line system by a numerical method. Also a vibration response, which is caused by water hammer, of the pipe-line system confirmed by an experiment and analyzed by a numerical method.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.3
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• pp.1742-1748
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• 1969

This is a method to determine the boundary line of reservoir flooding area which will be purchased. Until now, flood water level was used as the boundary line. By lowering this line from flood water level, purchasing cost of reservoir flooding area can be cut down. Sometimes, temporary flooding of arable land outside the boundary occurs. During the life of reservoir, flood damage to crop product on of this land must be indemified with net berefit from arable land between the bovndary line and normal water level. Following is the basic formula to determine the line. (Estimated flood damage to crop production of land outside the boundary line $\leqq$ Estimated net beneift from land between the boundary line and normal water level.) Minimum difference between both sides is needed to minimize the purchasing area. Flood damage and net benefit are estimated by hydrologic estimation with rainfall data and crop production estimation.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.2
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• pp.75-83
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• 2013

We applied a sensitive method based on on-line solid-phase extraction (SPE) and liquid chromatography/mass spectrometry (LC/MSD) using an electrospray interface for the determination of eleven perfluorinated compounds (PFCs) in water. The on-line connection suppressed the target loss by keeping the cartridge from drying, which resulted in improvement of the recovery and saving of the analytical time. For the on-line solid-phase extraction of 10 mL water samples, recoveries were between $80.4{\pm}5.2%{\sim}109.5{\pm}1.4%$ and limit of quantification (LOQ) were 3.6~15.9 ng/L for the PFCs. The total PFCs concentrations of the tributaries and main stream of Nakdong River water samples were in the range of $8.0{\sim}678.6{\mu}g/L$.