• Journal of Korean Society of Water and Wastewater
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• v.14 no.3
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• pp.271-280
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• 2000

This study was conducted to determine the applicable loading rate and to evaluate the possibility of using limestones as an alkalinity source for the removal of ${NO_3}^{-}-N$ remaining after denitrification/nitrification process with the down-flow sulfur packed bed reactor(SPBR). The pretreated sewage was fed to SPBR. Three SPBRs were filled with elemental sulfur particles and limestones and the volumetric ratios of sulfur to limestone were 0%, 12.5% and 25% for R-0%, R-12.5% and R-25%, respectively. The applicable loading rate was evaluated increasing flow rate with influent ${NO_3}^{-}-N$ concentration of 20 mg/L. For R-0% with external alkalinity supply, denitrification efficiency was greater than 96% up to loading rate of $354.8g\;{NO_3}^{-}-N/m^3{\cdot}day$, and corresponding EBCT was 1.4hr. For R-12.5% and R-25%, where alkalinity was supplied by the limestone filled in the reactor, denitrification efficiency was greater than 94% up to loading rate of $283.8g\;{NO_3}^{-}-N/m^3{\cdot}day$, and corresponding EBCT was 1.7hr. The slightly better performance of R-12.5 compared to R-25 suggests that the volumetric sulfur to limestone ratio of 12.5% was enough for the supply of alkalinity required for sulfur-utilizing denitrification. DO was appeared not showing inhibitory effect on sulfur-utilizing denitrification. The clogging of SPBR caused by the produced gas can effectively be eliminated by regular introduction of treated water in up-flow mode.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.27-37
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• 2017

Enrollment rate of childcare centers is an important indicator that regulates supply and demand of childcare services in South Korea, but monthly enrollment rate difference of childcare centers has not been studied. This study examines monthly enrollment rate difference from March 2015 to February 2016. Data for this study is drawn from the Korean Childcare Centers database and includes information about 39,775 childcare centers. Enrollment rate had increased steadily from 71.8% in March 2015 to 84.4% in January 2016, whereas it decreased by 50.3% in February 2016. The result showed that enrollment rate difference between March 2015 and January 2016 is about 13%p, and even those of between January and February 2016 is 32%p. Taken together, these findings suggest that the supply and demand of childcare services need to be regulated based on monthly enrollment information.

• Journal of Bio-Environment Control
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• v.17 no.3
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• pp.210-214
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• 2008

This experiment was carried out investigation of optimum concentration of supply nutrient solution in hydroponics of sweet pepper using coir substrates (coconut dust fiber=70% : 30%, v/v). During the growing period, it was found out that the electric conductivity (EC) would increase in proportion to the supply nutrient concentration but it was in inverse proportion to the moisture content. The pH of drainage was stable, while EC was high showing EC $7.3\;dS{\cdot}m^{-1}$ in EC $4.0\;dS{\cdot}m^{-1}$ of supply nutrient concentration. Also, standard deviation and coefficient of variation were high. Plant length was no difference by the supply nutrient concentration. Photosynthesis rate was generally high in supply nutrient concentration EC$4.0\;dS{\cdot}m^{-1}$. Fruit weight was heavy in supply nutrient concentration EC $4.0\;dS{\cdot}m^{-1}$, fruit shape was close to a regular square in supply nutrient concentration EC $3.5dS{\cdot}m^{-1}$.

• Fire Science and Engineering
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• v.33 no.5
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• pp.28-36
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• 2019

In the present study, the effects of supply gas and water mist on the heptane pool fire extinguishing performance were investigated using the full cone and hollow cone twin-fluid atomizers. Air or nitrogen of 30 lpm (Liter per minute; L/min) was used as the supply gas, and the experiments were conducted under the water flow rate conditions of 0 lpm (i.e., discharge of air or nitrogen only) and 0.085 lpm (i.e., discharge of water mist with supply gas). Experimental results confirmed that the use of water mist discharge with the supply gas and full cone spray pattern reduced the fire extinguishing time as compared to that of only supply gas discharge and hollow cone spray pattern. In addition, for the discharge of water mist using the full cone twin-fluid atomizer, water mist significantly affected fire extinguishing performance, whereas the effect of the supply gas was less pronounced. On the other hand, for the discharge of water mist using the hollow cone twin-fluid atomizer, the fire extinguishing time was remarkably reduced by the supply of nitrogen, as compared with that of air, indicating that the supply gas as well as water mist can significantly affect fire extinguishing performance.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.125-128
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• 2000

In this paper, we report a new damping circuit with a constant damping rate for RFID applications. The proposed damping circuit is used along with a over-voltage limiter and exhibits almost constant damping rates when the distance between the reader and the transponder varies. This results in keeping the power supply voltage of the transponder constant and in improved reading distances.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.859-866
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• 1993

With the object of doing mechanical grafting of cucurbitaceous vegetables, the grafting robot was developed in 1989. This robot consists of the following components : feeding wheels, grippers, conveying wheels, cutters , fixing clipper, discharger , controller and power supply. One cycle time to produce a grafted plant is about 3 seconds, Results of some cucumber grafting tests : successful grafting rate of 98 percent and after acclimation, a successful agglutination rate of 95 percent. These techniques are now transferring to the private company. The commercial robot will come into the market in this year.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.856-859
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• 2003

Currently, the domestic recycle rate of ELV parts is about 3%. The reason of the row rate of it is due to that consumer can not obtain the needed ELV parts. In order to supply the good parts to consumer. the equipment of the ELV disassembly is required. This research is to developed the lifter for ELV disassembly by considering the references such as the disassembly tool and equipment of the domestic and foreign ELV disassembly company.

• Proceedings of the Safety Management and Science Conference
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• 2002.11a
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• pp.125-131
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• 2002

In Currently, the domestic reuse rate of ELV parts is about 3%. The reason of the row rate of it is due to that consumer can not obtain the information of the needed ELV parts. In order to supply the needed information to consumer, the standard of the part classification of the ELV parts is required. This research is to develop the part classification system of the three digits and web site of ELV parts.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.1-7
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• 1998

To investigate the water balance in a paddy rice field with the pumping station for irrigation water supply, flow measurements and analysis on various components of water balance were carried out. The investigated area is 103.7 ha, and the irrigation water was supplied for 102 days during the total irrigation period starting from June 1. It was found that the consumption rate was increased as the growing stage was progressed. The variation of evapotranspiration rate was shown same tendency as the consumption rate, while no apparent tendency was found in infiltration rate upon different growing stages. And the ground water input to the area was predominant during the early stage of growing period, while ground water output from the study area was predominant at the end of the growing stage. The range of return flow rate, the ratio of total outflow to total inflow in every decad, was 57.6 to 85.7%. These values are slightly higher than reported values from the other investigation projects.

• The Korean Journal of Pharmacology
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• v.4 no.1 s.5
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• pp.37-39
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• 1968

A method for presenting the heart rate of intact animals as a kymographic record is described. A transistorized impulse generator with a dry battery power supply is used to produce pulses. The pulses are integrated and make a pen motor drived. The ability of the instrument to follow a wide range of heart rate change is demonstrated. The instrument is especially usefull to observe an acute and transitory heart rate change. A method for changing the heart beat to sound and a method for counting the heart rate of intact animal and isolated preparations by employing post office counter were also described.