• Journal of fish pathology
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• v.31 no.2
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• pp.93-99
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• 2018

Edwardsiella tarda predominantly causes edwardsiellosis in fish at high temperature, but is rarely isolated from water when water temperature is low. However, E. tarda is viable but nonculturable (VBNC) in low water temperature, but it can be revived when water temperature rises and cause disease to fish. Therefore, in order to prevent disease, it is very important to identify pathogens that are in the VBNC state in environmental water. In this study, E. tarda cells in the VBNC state were detected by the ethidium monoazide (EMA)-PCR method using the low-temperature oligotrophic sea water microcosm obtained by inoculation of E. tarda at a concentration of $10^8CFU/ml$. In order to distinguish between live and dead bacteria in E. tarda, each sample was treated with EMA at different concentrations, photoactivated with a 500 W halogen lamp, and PCR was performed with E. tarda specific primer. At the concentration of $10^7CFU/ml$ bacterium, DNA amplification was observed only in the live cells when treated with $60{\mu}g/ml$ of EMA, and smaller amounts of live cells could be distinguished from dead cells by adjusting the EMA concentration. In addition, the VBNC cells of E. tarda in the oligotrophic low temperature seawater microcosm were estimated to be in the range of $10^4{\sim}10^5CFU/ml$ by EMA-PCR. Therefore, it is possible to detect VBNC cells that will act as potential pathogens in environmental water using EMA-PCR method, and quantitative confirmation using concentration change is also possible.

• Membrane Journal
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• v.12 no.3
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• pp.165-170
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• 2002

Membrane process was investigated to recover useful components, such as protein from rice-washing water generated in the production of the washed-rice. The filtration experiments were carried out using not only a dead-end Amicon cell to determine suitable membranes but also a hollow fiber ultrafiltration, spiral wound nanofiltration and reverse osmosis modules for home water purification. Ultrafiltration module(molecular weight cut-off : 10,000 dalton) was not suitable for recovery of useful components or protein in the rice-washing water, but nanofiltration and reverse osmosis modules showed a good performance. in the case of 250% concentration of the rice-washing water contained about 9% protein the proteins in concentrates of nanofiltration and reverse osmosis were 18% and 22%, which were about 2 and 2.4 times higher protein concentrations than those of feed, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.232-237
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• 1991

Digital Variable Structure Controller(DVSC) is proposed to control variable speed recirculating pump for hot-water heating control system. In this study, nonlinear sliding line is used beyond output error boundary layer and PID sliding line is used within the layer. For long dead time compensation, constraint is added to Smith predictor algorithm. Steady state error is eliminated by using the proposed sliding line in spite of heating load change. By decreasing sampling time, good sliding motion is yielded but system output noise bv flow dynamics is amplified.

• International Journal of Control, Automation, and Systems
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• v.5 no.1
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• pp.79-85
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• 2007

In this paper, a real-coded genetic algorithm is proposed for identification of time delay systems from step responses. FOPDT(First-Order Plus Dead-Time) and SOPDT(Second-Order Plus Dead-Time) systems, which are the most useful processes in this field, but are difficult for system identification because of a long dead-time problem and a model mismatch problem. Genetic algorithms have been successfully applied to a variety of complex optimization problems where other techniques have often failed. Thus, the modified crossover operator of a real-code genetic algorithm is proposed to effectively search the system parameters. The proposed method, using a real-coding genetic algorithm, shows better performance characteristics when compared to the usual area-based identification method and the directed identification method that uses step responses.

• 한국생태학회:학술대회논문집
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• 2002.08a
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• pp.127-131
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• 2002

In order to elucidate the characteristics of standing crop biomass, production and nutrient content of dead bole in mature ecosystem, we surveyed the dynamics of decaying bole of old-aged deciduous forest in 1993 and 2002 in Kwangnung Experimental Forest Station. In addition, we and estimated annual bole production, water content, wood density and nutrient content and compared the results with that of temperate ecosystem. Total dead wood biomass was estimated to be 5.6ton/ha in 1993 and 17.6ton/ha in 2002. Standing dead tree accounted for a total of 1.1ton/ha in 1993 and 4.8ton/ha in 2002, which was 20% and 27% of the sum of dead bole mass in 1993 and 2002, respectively. Annual production of bole biomass was 1.3 ton/ha/yr. These values fall into the low range of dead wood biomass for the mature temperate ecosystems. Tree species composing standing bole was mainly Quercus and Carpinus trees. This bole species composition resembles alive species composition of this forest. Water content of bole increased as positive logarithmically, but wood density of bole decreased as negative exponentially along with the progress of decay. N, P, Ca and Mg concentrations in decaying boles generally increased with decay, except for K. Annual nutrient input via dead bole is 1.6kg/ha/yr for N, 0.04 kg/ha/yr for P. 1.0 kg/ha/yr for K, 1.7kg/ha/yr for Ca and 0.3 kg/ha/yr for Mg, respectively.

• The Korean Journal of Ecology
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• v.25 no.4
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• pp.261-265
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• 2002

In order to elucidate the characteristics of standing crop biomass, production and nutrient content of dead bole in mature ecosystem, we surveyed the dynamics of decaying bole of old-aged deciduous forest in 1993 and 2002 in Kwangnung Experimetal Forest Station. In addition, we and estimated annual bole production, water content, wood density and nutrient content and compared the results with that of temperate ecosystem. Total dead wood biomass was estimated to be 5.6ton/ha in 1993 and 17.6 ton/ha in 2002. Standing dead tree accounted for a total of 1.1 ton/ha in 1993 and 4.8 ton/ha in 2002, which was 20% and 27$\%$ of the sum of dead bole mass in 1993 and 2002, respectively. Annual production of bole biomass was 1.3 ton/ha/yr. These values fall into the low range of dead wood biomass for the mature temperate ecosystems. Tree species composing standing bole was mainly Quercus and Carpinus trees. This bole species composition resembles alive species composition of this forest. Water content of bole increased as positive logarithmically, but wood density of bole decreased as negative exponentially along with the progress of decay. N, P, Ca and Mg concentrations in decaying boles generally increased with decay, except for K. Annual nutrient input via dead bole is 1.6 kg/ha/yr for N, 0.04 kg/ha/yr for P, 1.0 kg/ha/yr for K, 1.7 kg/ha/yr for Ca and 0.3 kg/ha/yr for Mg, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.336-340
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• 2009

This paper presents experimental results carried out on the purge characteristic of the anodic dead-end mode fuelcell and how to improve the cell performance by pulsation effects. The dead-end mode fuelcell has some merits that a fuel supplying device is not needed and the cell power is higher than that in the open mode fuelcell. However, the purge is necessary for preventing the porous media from being flooded by liquid water formed in the channel. At this time, the un-reacted fuel is discharged with the liquid water together in purge process. The discharged fuel can make the fuel efficiency lower. Therefore, the number of purge times should be decreased for the better fuel efficiency. In this study, the outlet of the anode channel was equipped with a purge solenoid valve and a pulsation generator. The purge times was decreased when the current density decreased and operation pressure increased without the pulsation effects. In addition, when the pulsation effects such as various frequencies or amplitudes were applied, purge times was alleviated up to 40%.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.495-502
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• 2013

Hydraulic dead-zone and particle removal efficiency in the base frame of a constructed wetland was evaluated with computational fluid dynamics (CFD). The fraction of hydraulic dead-zone was estimated to be 1.2-2.1 % (v/v) and it was attributed to the artificial islands developed in the constructed wetland. Solids deposition rate could be increased with higher hydraulic retention time (HRT, ranged from 2.2 to 4.2 hr) of the wetland and larger particle size (ranged from 10 to $50{\mu}m$) in the influent. Experimental results showed that the volume concentration of the particles smaller than $10{\mu}m$ in diameter was varied from $1.99{\times}10^3{\mu}m^3/ml$ (HRT 12.8 hr) to $3.92{\times}10^3{\mu}m^3/ml$(HRT 2.2 hr) in the influent of the constructed wetland. With the effluent volume concentration data, removal efficiency of those particles was calculated to be 71.2 and 24.7 % when the HRT was 12.8 and 2.2 hr, respectively. Similar trend with the HRT variation could be identified with CFD analysis.

• Membrane and Water Treatment
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• v.7 no.4
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• pp.313-325
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• 2016

South Africa recognises piped water as the main source of safe drinking water supply. Remote areas do not have access to this resource and they rely solely on surface water for survival, which exposes them to waterborne diseases. Interim point of use solutions are not practiced due to their laboriousness and alteration of the taste. Bio-ultra low pressure driven membrane system has been noted to be able to produce stable fluxes after one week of operation; however, there is limited literature on South African waters. This study was conducted on three rivers namely; Umgeni, Umbilo and Tugela. Three laboratory systems were setup to evaluate the performance of the technology in terms of producing stable fluxes and water that is compliant with the WHO 2008 drinking water guideline with regards to turbidity, total coliforms and E.coli. The obtained flux rate trends were similar to those noted in literature where they are referred to as stable fluxes. However, when further comparing the obtained fluxes to the normal dead-end filtration curve, it was noted that both the Umbilo and Tugela Rivers responded similarly to a normal dead-end filtration curve. The Umgeni River was noted to produce flux rates which were higher than those obtainable under normal dead-end. It can be concluded that there was no stabilisation of flux noted. However, feed water with low E.coli and turbidity concentrations enhances the flux rates. The technology was noted to produce water of less than 1 NTU and 100% removal efficiency for E.coli and total coliforms.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1303-1308
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• 2008

Keeping cooling water temperature higher within the allowable range helps marine engines to run in more efficient condition especially when the engine load is low. Temperature control of jacket cooling water in outlet side of main engine has been more widely adopted to ships these days for the purpose to reduce fuel consumption rate. But If the temperature sensor for the control loop is placed at the outlet of engine, it brings more difficulties in attaining stable and desirable properties due to dead times included in pipe length and engine itself comparing to the case where the measuring point is at the inlet side of main engine. In relation with this problem, Feed-forward control could be one of realistic solutions as it reveals good properties and requires less cost for system configuration. This study suggests a forward control system which leads to improved temperature control performances to disturbance signals which could arise from variation of engine load or weather condition. Two dead times in the modelling were described, considering pipe length between the actuator and the engine as well as the thermal process inside the engine. The results of analysis were shown by simulations to confirm responses under different conditions.