• The Korean Journal of Emergency Medical Services
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• v.11 no.3
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• pp.191-204
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• 2007

This study analyzes use and operation of silver ambulance with 110 patients who had used silver ambulance in Gwangju and Jeonnam regions from June of 2006 to June of 2007 and 53 paramedics who are involved directly in ambulance operation and the results of this analysis are as follows. 1. Users' health conditions, 69.1% of users answered as bad and 67.3% suffered from chronic diseases over 3 months and it was found that they used silver ambulance due to their bad health conditions. 2. Cronbach's alpha was 0.630 and family function index was generally reliable and solution was high as 1.60, but total points were low as 7.11 and it was considered that they had family troubles. 3. On the question of ambulance use, 44.5% answered they used it because it is free, 53.6% used it for appointed medical examination and treatment and 18.1% used it for emergency. 4. Degrees of satisfaction with ambulance and paramedics were 95.4% and 76.4% respectively and 80.0% of ambulance users answered ambulance arrived quickly within 15 min. 5. Correlation($x^2 $) between family or relative's residence and frequency of visits was 86.367 and its significance probability was 0.00 and it was found that it was significant in the level of 0.1%, but correlation($x^2 $) between visitors other than family or relatives and frequency of visits was 14.768 and its significance probability was 0.25 and it was found that it was not significant in the level of 5%. 6. Correlation($x^2 $) between transfer operation speed and mobilization time was found that it was not significant in the level of 5%. Correlation($x^2 $) between their own health condition purpose of ambulance use was 13.802 an 5.696 and its significance probability was 0.93 and it was found that it was not significant in the level of 1%, and it was considered because paramedics carried patients with safe operation.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.289-299
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• 2013

Objectives: For the field application of the dielectric barrier discharge plasma reactor, scale-up of the plasma reactor is needed. This study investigated the possibility of inactivation of microorganisms in sewage using pilot multi-plasma reactor. We also considered the possibility of degradation of total organic carbon (TOC) and nonbiodegradable matter ($UV_{254}$) in sewage. Methods: The pilot plasma reactor consists of plasma reactor with three plasma modules (discharge electrode and quartz dielectric tube), liquid-gas mixer, high voltage transformers, gas supply equipment and a liquid circulation system. In order to determine the operating conditions of the pilot plasma reactor, we performed experiments on the operation parameters such as gas and liquid flow rate and electric discharge voltage. Results: The experimental results showed that optimum operation conditions for the pilot plasma reactor in batch experiments were 1 L/min air flow rate), 4 L/min liquid circulation rate, and 13 kV electric discharge voltage, respectively. The main operation factor of the pilot plasma process was the high voltage. In continuous operation of the air plasma process, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal condition of 13 kV were $10^{2.24}$ CFU/mL, 56.5% and 8.6%, respectively, while in oxygen plasma process at 10 kV, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal conditions were $10^{1.0}$ CFU/mL, 73.3% and 24.4%, respectively. Electric power was increased exponentially with the increase in high voltage ($R^2$ = 0.9964). Electric power = $0.0492{\times}\exp^{(0.6027{\times}lectric\;discharge\;voltage)}$ Conclusions: Inactivation of microorganisms in sewage effluent using the pilot plasma process was done. The performance of oxygen plasma process was superior to air plasma process. The power consumption of oxygen plasma process was less than that of air plasma process. However, it was considered that the final evaluation of air and oxygen plasma must be evaluated by considering low power consumption, high process performance, operating costs and facility expenses of an oxygen generator.

• Membrane Journal
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• v.1 no.1
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• pp.34-43
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• 1991

The relationships between affinity of membranes and optimum operation conditions were investigated in the pervaporation of water(1)/ethanol(2) mixture through cellulose acetate(CA) membranes having more affinity to water and silicone rubber(SR) membranes having more affinity to ethanol. CA and SR membranes were prepared and amount of sorption, sorption selectivity, pervaporation separation factor and pervaporation rate in both of membranes were determined and compared. The effects of downstream pressure were analyzed using Thompson diagram and the sorption and pervaporation characteristics with composition of feed and operation temperature were examined in terms of affinity, activity coefficient, plasticizing effect and activation energy of individual species. In the separation of water through CA membranes, high performance of both pervaporation separation factor (water to ethanol, $[\alpha^2_1]_{PV}$) and pervaporation rate was obtained in the conditions of low downstream pressure, middle range of feed concentration and high temperature. In the separation of ethanol through SR membranes, pervaporation separation factor(ethanol to water, $[\alpha^2_1]_{PV}$) increased with downstream pressure and decreased with concentration of ethanol in feed and operation temperature, while pervaporation rate showed opposite trends to those of ($[\alpha^2_1]_{PV}$).

• Korean Journal of Agricultural Science
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• v.46 no.3
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• pp.613-627
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• 2019

The purpose of this study was to design a powertrain for a 78 kW AWD (all wheel drive) electric tractor by analyzing the combination of various reduction gear ratios on a commercial motor using data from actual agricultural work and driving conditions. A load measurement system was constructed to collect data using wheel torque meters, proximity sensors, and a data acquisition system. Field experiments for measuring load data were performed for two environmental driving conditions (on asphalt and soil) and four agricultural operations (plow tillage, rotary tillage, loader operation, and baler operation). The attached implements and gear stages were selected through farmer surveys. The range of the reduction ratio was determined by selecting the minimum reduction ratio needed to satisfy the torque condition required for agricultural operations and the maximum reduction gear ratio to satisfy the maximum travel speed. The minimum reduction gear ratio selected was 57 in consideration of the working load condition and the maximum reduction gear ratio selected was 62 considering the maximum running speed. In the range of the reduction gear ratio 57 - 62, the selected motor satisfied all working torque conditions. As a result, the combination of the selected motor and reduction gear ratio was applicable for satisfying the loads required during agricultural operation and driving operation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.398-402
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• 2008

Recently, the development of superconducting fault current limiters (SFCLs) has been required as power demands increase in the power system. A distribution-level prototype resistive SFCL using coated conductor (CC) has been developed by Hyundai Heavy Industries Co., Ltd. and Yonsei University for the first time in the world. The ratings of the SFCL are 13.2kV/630A at normal operating condition. A novel non-inductive winding method is used in fabricating coils so there is almost zero impedance during normal operation. The distribution SFCL is cooled by sub-cooled liquid nitrogen $(LN_2)$ of 65K and 3 bar to enhance cryo-dielectric performance, critical current density, and thermal conductivity. In order to make reliable operation of an SFCL in real power systems, we monitored and controled its operation conditions by using supervisory control and data acquisition (SCADA) method. Thus, a monitoring system for the SFCL employing information technology (IT) is proposed and developed to be on the lookout for the operation conditions such as inside temperature, inside pressure, $LN_2$ level, voltage and current. Since operation temperature should be kept constant, bang-bang control for temperature feedback with a heater attached to the cold head of cryo-cooler is applied to the system. Short-circuit tests with prospective fault current of 10kA and AC dielectric withstand voltage tests up to 143kV for 1 minute were successfully performed at Korea Electrotechnology Research Institute. This paper deals with the development of a distribution level SFCL and its monitoring system for reliable operation.

• Journal of Korea Water Resources Association
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• v.57 no.4
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• pp.249-261
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• 2024

Climate change has intensified the severity of extreme floods, presenting substantial challenges to dam management and operation. Traditionally, flood control strategies for dam operations have been based on theoretical scenarios, such as designed floods, without taking into account downstream conditions. However, in practice, managing floods involves operating dams based on climate forecasts. This strategy encounters challenges due to the limited predictability of climate forecasts, which in turn leads to uncertainty in decisionmaking among dam managers. This study proposes a flood control approach for dam operations that involves gradually increasing the outflow, considering the operational constraints and potential downstream damage, based on inflow data. The effectiveness of this method was assessed through simulation, employing both a designed flood and data from the most significant historical flood. The dam operation strategy for flood control presented in this study provides a framework for dam operators, facilitating consistent decisionmaking in flood management by integrating realistic dam operational conditions.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.352-359
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• 2009

KEPRI is developing a Korean type coal-gasification system and the scale is 20 ton/day. Prior to this pilot plant, a 1 ton/day class gasification system will be used for pre-testing of several coal types. This paper introduces the configuration and design conditions of this 1 ton/day class system, presenting the gas/coal ratio, oxygen/coal ratio, cold gas efficiency, CFD analysis of gasifier, and others. The existing combustion furnace for residual oil was retrofitted as a coal gasifier and a vertical and down-flow type burner was manufactured. Ash removal is carried out through a water quencher and a scrubber following the quencher, and the sulfur is removed by adsorption in the activated carbon tower. The gas produced from the gasifier is burned at the flare stack. In this paper, the results of design conditions and initial operation conditions of I ton/day gasification system are compared together.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.307-310
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• 2016

The operational cost for maintaining the superconductivity of high-temperature superconducting (HTS) cables needs to be reduced for feasible operation. It depends on factors such as AC loss and heat transfer from the outside. Effective operation requires design optimization and suitable operational conditions. Generally, it is known that critical currents increase and AC losses decrease as the operational temperature of liquid nitrogen ($LN_2$) is lowered. However, the cryo-cooler consumes more power to lower the temperature. To determine the effective operational temperature of the HTS cable while considering the critical current and AC loss, critical currents of the HTS cable conductor were measured under various temperature conditions using sub-cooled $LN_2$ by Stirling cryo-cooler. Next, AC losses were measured under the same conditions and their variations were analyzed. We used the results to select suitable operating conditions while considering the cryo-cooler's power consumption. We then recommended the effective operating temperature for the HTS cable system installed in an actual power grid in KEPCO's 154/22.9 kV transformer substation.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.1081-1090
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• 2024

The liquid Lead-bismuth eutectic is used as the coolant for Gen-IV reactor concepts. However, due to its strong corrosive and high operating temperature, it is difficult to accurately measure the flow rate in long-term operating conditions. Venturi flowmeter is a simple structured flowmeter, which plays a very important role in the flow measurement of high-temperature liquid metals, especially since the existing flowmeters are difficult to be competent. It has the advantages of easy maintenance and stable operation. Therefore, it is necessary to study the operating conditions of the venturi flowmeter under high-temperature conditions. This work performs a series of simulations of the fluid-solid interaction between the flow liquid metal and venturi flowmeter with COMSOL software, including the dimensional sensitivity analysis of the venturi flowmeter to explore the most suitable structure and parameters for liquid heavy metal, the sensitivity analysis of the geometric parameters of the venturi tube on the varying conditions. It shows that when the contraction angle of the venturi flowmeter is 33°, the diffusion angle is 13°, the diameter of the throat is 8 mm, and the temperature of the lead-bismuth eutectic is 733.15 K, it is most suitable for the measurement in the lead-bismuth circuit.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.11a
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• pp.253-258
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• 2003