• Industry Promotion Research
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• v.1 no.1
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• pp.129-135
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• 2016

This study verified the water saving effect in case of raising water rate depends on water rate awareness. The study results showed that the perceived appropriacy of government aid(p<.001), home water rate(p<.01), water rate pricing system, water rate, water rate diffrences depend on use and area(p<.05) significantly affected the degree of agreement of raising water rate. Also, education, residence, member of household, occipation, monthly household income, monthly water rate significantly affected the degree of agreement of raising water rate, consumer behavior for saving water. This study provided implication for water rate pricing policy by analyzing the water saving effect in case of raising water rate depends on water rate awareness and revealing the determinants of the degree of agreement of raising water rate.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.78-84
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• 1998

The fluid system such as, the quantity control of raw water, chemicals control in the purification, the waste water system as well as in the feed water or circulation system of the power plant and the ventilation system is controlled with the valve and moter pump. The system's performance and the energy saving of the fluid systems depend on control of method and delicacy. Until, PI controller use in these system but it cannot control delicately because of the coupling in the system loop. In this paper we configure a single flow system to the multi variable system and suggest the application of 2-DOF PID controller and the tuning methods by the neural network to the electrical power of the flow control system. the 2-DOF controller follows to a setpoint has a robustness against the disturbance in the results of simulation. Keywords Title, Intelligent control, Neuro control, Flow control, 2 - DOF control., 2 - DOF control.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.70-78
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• 2009

Floodplain areas of major South Korean rivers were determined by analyzing topographical maps and hydraulic properties of floodplain soil were measured using disc tension infiltrometer. To assess the possibility of treating secondary effluents of municipal wastewater with floodplain soil, a computer code for the analysis of unsaturated flow in soil was employed along with searches conducted in the literature. Based on the data generated, an estimate of total floodplain filtration capacity in Korea was obtained. The results of our study reveal that Korean floodplains have surface soil that is adequate for treating water. Moreover, the distributions of floodplains are substantial over the entire reaches of the rivers, indicating that the conditions are favorable for floodplain filtration as additional treatment of secondary effluent. The capacity of floodplain filtration in Korea is circa 182,000,000 $m^3$/day and most of the rivers are estimated to have enough capacity of floodplain filtration to meet all the secondary effluent, indicating that this technology may be expected to make further improvements on river water quality. Furthermore, this method may also be applied to better the source-water quality for drinking water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.6-13
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• 2017

This study examines the effect of the type and number of orifices in an in-line mixer to improve the mixing performance and pressure loss. Recently, in-line non-power-consuming mixers have been increasingly used to complement mechanical mixers, which have a long dwell time, noise, excessive energy consumption, and high maintenance costs. An in-line mixer with an orifice for efficient mixing in water treatment was examined by numerical analysis using the commercial code FLUENT. The flow characteristics of pressure loss and velocity distribution within the mixer and the mixing efficiency were compared with and without the orifices. The CFD results show that the mixing efficiency was improved, but the pressure loss was increased by the in-line mixer with an orifice. A sensitivity study was also done on the principal parameters.

• Journal of Technologic Dentistry
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• v.42 no.4
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• pp.313-320
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• 2020

Purpose: The purpose of this study is to compare and analyze the accuracy of single crowns based on the type of occlusal surface. Methods: A single crown wax pattern was fabricated in three types of occlusal surface. The prepared wax pattern was replicated with silicone, and stone was injected to create a stone model. The prepared specimens were scanned using a model scanner. Scans were classified into three groups, and each scan was performed six times to analyze the trueness and precision of a single crown. In addition, only the occlusal surface area was analyzed for trueness and precision. Data were analyzed using the Kruskal-Wallis H test, a nonparametric test (α=0.05). Results: With regard to the trueness value of the occlusal scan area, the no occlusal tooth attrition (NA) group showed the largest error of 3.5 ㎛, and the complete occlusal tooth attrition (CA) group showed the lowest value of 3.1 ㎛. The NA group had the greatest precision, and the medium occlusal tooth attrition (MA) group and CA group showed a low precision value of 3.2 ㎛; the difference between the groups was statistically significant (α=0.05). In the color difference map, the CA group showed a lower error than the NA group. Conclusion: The occlusal surface with severe attrition had excellent accuracy, but the accuracy of the group without attrition was low. There were significant differences between groups, but clinically acceptable values were shown.

• Membrane Journal
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• v.32 no.2
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• pp.126-132
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• 2022

Water purifiers have a quite different characteristic in comparison with general membrane water treatment processes in which the running and resting are repeated dozens of times a day. In the case of water purifiers using reverse osmosis membranes, this characteristic makes a phenomenon that the total dissolved solids (TDS) of permeate in water purifiers at the beginning of running shows a higher value than a normal value (TDS reduction is lower than a normal value). It is called "TDS creep". The effects of resting times and feed concentrations on the TDS creep were investigated. The feed flushing, the volume increase in permeate side and the flushing with purified water were applied to reduce TDS creep and the effectiveness were observed. Among these trials, the minimization of concentration between feed and permeate side of reverse osmosis membrane like the flushing with purified water can be an ultimate solution to reduce the TDS creep.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.115-122
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• 2017

Objective of this research was to investigate the influence of lowered substrate pH on the reduction of bicarbonate injury in the vegetative growth of 'Ssanta' strawberry. The acid substrate was formulated by mixing sphagnum peat moss with pine bark (5:5, v/v) and the pH, EC, and CEC of the substrate were 4.07, $0.46dS{\cdot}m^{-1}$, and $91.3cmol^+{\cdot}kg^{-1}$, respectively. To adjust the pH of acid substrate, various amount of dolomitic lime [$CaMg(CO_3)_2$] were incorporated with the rate of 0 (untreated), 1, 2, 3, and $4g{\cdot}L^{-1}$. Then, mother plants were transplanted and grown with fertilizer solution containing $240mg{\cdot}L^{-1}$ of the $HCO_3{^-}$ and equal concentrations of essential nutrients to Hoagland solution. In growth of 'Ssanta' strawberry, fresh weight of mother plants were the highest in the treatment of $2g{\cdot}L^{-1}$ dolomitic lime such as 102.1 g followed by 94.7 g in $1g{\cdot}L^{-1}$, 91.2 g in $3g{\cdot}L^{-1}$, 75.7 g in $0g{\cdot}L^{-1}$ and 72.3 g in $4g{\cdot}L^{-1}$ treatments. The dry weight showed a similar tendency to fresh weight. At 140 days after transplanting, 5.8, 9.8, 11.8, 8.8, and 5.0 daughter plants were derived from each of the mother plants in the treatments of 0, 1, 2, 3, and $4g{\cdot}L^{-1}$ dolomitic lime, respectively. The highest occurrence of daughter plants were observed in the treatments $2g{\cdot}L^{-1}$ dolomitic lime. The substrate pH and bicarbonate concentration of 'Ssanta' strawberry seedlings in the 1 and $2g{\cdot}L^{-1}$ dolomitic lime treatments were maintained at a proper range such as 5.6 to 6.2. The micro-nutrient contents of above ground tissue in mother plants were the highest in $2g{\cdot}L^{-1}$ and the lowest in $4g{\cdot}L^{-1}$ dolomitic lime treatment. The above results indicate that incorporation rate of dolomitic lime in acid substrate with the pH of around 4 is $2g{\cdot}L^{-1}$ to raise the 'Ssanta' strawberry in propagation.

• Knowledge Management Research
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• v.24 no.1
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• pp.245-271
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• 2023

The change to the data economy requires a new analysis beyond ordinary research in the management field. Data matching refers to a technique or processing method that combines data sets collected from different samples with the same population. In this study, statistical matching was performed using random hotdeck and Mahalanobis distance functions using 2020 Survey of Korea Venture Firms and 2020 Korea Innovation Survey datas. Among the variables used for statistical matching simulation, the industry and the number of workers were set to be completely consistent, and region, business power, listed market, and sales were set as common variables. Simulation verification was confirmed by mean test and kernel density. As a result of the analysis, it was confirmed that statistical matching was appropriate because there was a difference in the average test, but a similar pattern was shown in the kernel density. This result attempted to expand the spectrum of the research method by experimenting with a data matching research methodology that has not been sufficiently attempted in the management field, and suggests implications in terms of data utilization and diversity.

• Korean Journal of Microbiology
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• v.51 no.3
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• pp.271-279
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• 2015

Lactoferrin (LF) is a multifunctional, iron-binding glycoprotein found in physiological secretions of mammals. LF shows antibacterial, antiviral and antifungal activities. In the present study, a gene encoding the N-terminal lobe of human lactoferrin (hLF) was isolated, cloned and expressed in methylotrophic yeast, Pichia pastoris. The recombinant hLF-N (rhLF-N) protein was secreted into the culture medium at the level of $458{\mu}g/ml$ in 3 L fermentor. The size of purified hLF-N was estimated as 35 kDa when analyzed by SDS-PAGE and western blotting. The rhLF-N was further confirmed by immunodiffusion using the anti-hLF polyclonal antibody. The expression profile analysis by qRT-PCR showed that the relative mRNA expression of rhLF-N was maximal after 2-3 days of methanol induction and reduced gradually at 4 days. The purified rhLF-N showed broad antibacterial activities against the pathogens such as Staphylococcus aureus, E. coli, Pseudomonas aeruginosa, Burkholderia cepacia, and Salmonella typhimurium. However, rhLF-N showed relatively lower activity when compared to peptides derived from LF. In spite of this weak activity, the rhLF-N expressed in P. pastoris might be more advantageous for the industrial application, because rhLF-N is secreted into the culture medium and the production can also be increased by optimization of culture conditions.

• Membrane Journal
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• v.28 no.2
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• pp.83-89
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• 2018

Hydrophobic porous PVDF hollow fiber membranes for Membrane Distillation (MD) were fabricated by a combination of thermally induced phase separation (TIPS) and stretching. The purpose of this study is to investigate the shape and operating conditions of the module and the effect of piping size on parallel connection. In the optimization experiment of the vacuum membrane distillation module, the flux decreased as the packing density and length of the membrane in the module increased. When the module was connected vertically, it was confirmed that the nearest to the inlet of the vacuum port was the highest flux. In selecting the size of the header pipe of the module, it was confirmed that the maximum flux is shown when the inner diameter area of the hollow fiber membrane and the inner diameter area of the header pipe are the same. Also, it is necessary to find the optimal linear velocity because the higher the linear velocity in the module, the higher the flux, but the pressure acting on the module also increases proportionally.