• Analytical Science and Technology
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• v.8 no.1
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• pp.69-77
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• 1995

The instrumentation and operating characteristics of a gas-jet assisted radio frequency glow discharge atomic absorption spectrometry(RF-GDAAS) are studied. The roles of discharge power, pressure as well as gas flow rate on the sample loss rate and absorbance are described in this paper. Results show that the optimum discharge conditions depend on pressure and discharge power as well as on the gas flow rate. The gas flow rate plays as an important parameter in RF-GDAAS. Absorbance increases as the gas flow rate increase up to 600ml/min., and the optimum absorbance is obtained at the pressure of 3 mbar. The absorbance increases when the discharge power increases as expected, however, the instability of the system due to the heat might be the trade off factor. The linear calibration curves of Ni and Cr in stainless steel(BAS 461-468) and brass (KSS 1121-1126) are obtained with RF-GDAAS.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.4
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• pp.243-250
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• 2019

This objective of this study was to investigate the degradation characteristics of phenol, a refractory substance, by using a submerged dielectric barrier discharge (DBD) plasma reactor. To indirectly determine the concentration of active species produced in the DBD plasma, the dissolved ozone was measured. To investigate the phenol degradation characteristics, the phenol and chemical oxygen demand (COD) concentrations were evaluated based on pH and the discharge power. The dissolved ozone was measured based on the air flow rate and power discharged. The highest dissolved ozone concentration was recorded when the injected air flow rate was 5 L/min. At a discharge power of 40W as compared to 70W, the dissolved ozone was approximately 2.7 - 6.5 times higher. In regards to phenol degradation, the final degradation rate was highest at about 74.06%, when the initial pH was 10. At a discharged power of 40W, the rate of phenol decomposition was observed to be approximately 1.25 times higher compared to when the discharged power was 70W. It was established that the phenol degradation reaction was a primary reaction, and when the discharge power was 40W as opposed to 70W, the reaction rate constant(k) was approximately 1.72 times higher.

• YAKHAK HOEJI
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• v.37 no.1
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• pp.76-83
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• 1993

The changes in discharge current, emission and/or oscillation frequency of the electric oscillation of a glow discharge are the potential sensitive measure of the concentration of an impurity in the argon plasma supporting gas. A single jet enhanced glow discharge has been interfaced with the gas chromatograph via 1/8" O.D. tube with a heating pad to study the changes in discharge current. To investigate the optimum operating conditions of the glow discharge system as detector for gas chromatography, pressure, gas flow rate, discharge current, distance between the anode and the cathode have been studied.

• The Journal of the Korea Contents Association
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• v.17 no.2
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• pp.535-542
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• 2017

There is a big difference of discharge rate between drought and flood period in Korea since the importance of water resources management has come to the fore. To know a river characteristics, it needs to estimate river discharge accurately. River discharge is calculated using the measured velocity of cross section and the estimated area of watercourse as input parameters into continuity equation. Generally, flow rate over a river is estimated from the relation equation between level and discharge, in this case, there are weakness for only the equal depths and the equal discharge estimated. In the present study, therefore, water surface slope was estimated using measured water level of Seongseo water level observation station and measured water level using ADVM at Gangchang Bridge. And then, we developed the discharge calculation equation using water surface slope. A method to easily calculated flow rate from the measured depth of the two points that are suggested by reflecting water surface slope because natural stream is unsteady flow, not uniform flow or not steady flow.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.807-812
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• 2015

Li-ion batteries are energy sources that are widely used in applications such as notebooks, cellular phones, power tools, and vehicles. They are devices in which stored chemical energy is changed to electrical energy by electrochemical reactions. They have a high energy density, small size, and are lightweight. In particular, power tools and vehicles require high charge/discharge rates. Therefore, in this paper, we perform electrochemical simulations using a commercial finite-element analysis program to determine the high discharge-rate characteristics of Li-ion cells. In addition, by performing high discharge-rate simulations, we found that the limited discharge current was 63 A. Based on the results obtained, we investigate the behavior of Li-ion cells with a high rate of discharge.

• Quality Improvement in Health Care
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• v.8 no.2
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• pp.208-217
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• 2001

Background : The objective of this study is proving the basic data for developing a management system for the discharges against medical advice(AMA) by identifying the characteristics of the AMA patients of an university hospital for 10 years. Methods : By using discharge abstract data base, we divided the total discharges(435,254) into two groups, discharge against medical advice and discharge with discharge order. We confirmed the characteristics of AMA group by analyzing discharge abstract data of the both groups by SAS software V6.12 and $x^2$ test. Medical records of AMA patients in the year 2000 were reviewed to identify the reasons for AMA which we couldn't extract from discharge abstract DB. Result : The total number of AMA for 10 years were 9,358(2.15%) and the AMA rate has been continuously decreased for 10 years. Male, admission through emergency room, discharges admission via other hospital, patients without operation during hospitalization, discharges in hopeless or not improved condition showed higher AMA rate. The AMA rate was higher as the age of the patients was higher, and the average length of stay was longer in AMA patients than in those with discharge order. The AMA rate in psychiatry was highest(14.3%) and it was higher in surgery departments than those of medical or other sections. The AMA rate varied by attending physicians even in the same department and it was statistically significant. Patients with the principal diagnosis of "medical observation and evaluation for suspected diseases" showed the highest AMA rate(15.5%), and that of schizophrenia or psychosis was the nest. One hundred twenty-one patients(19.5%) out of 622 AMA in 2000 discharged against medical advice for transfer to order health care facilities. Among them 71 patients(58.7%) discharged with their medical care information, such as copies of medical record, medical certificates, summaries, etc. Written oath of the patients discharged AMA was filed in their medical records in 466 cases(74.9%) although some of them were incomplete. Conclusion : Characteristics of AMA discharge could be used as the basic data in developing a system to manage the patients who have risk factors to leave the hospital against medical advice. By reducing number of patients leaving the hospital against medical advice we can increase satisfaction of medical providers and consumers.

• Korean Journal of Materials Research
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• v.26 no.12
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• pp.696-703
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• 2016

In this study, we intensively investigated the effect of conductive additive amount on electrochemical performance of organic supercapacitors. For this purpose, we assembled coin-type organic supercapacitor cells with a variation of conductive additive(carbon black) amount; carbon aerogel and polyvinylidene fluoride were employed as active material and binder, respectively. Carbon aerogel, which is a highly mesoporous and ultralight material, was prepared via pyrolysis of resorcinol-formaldehyde gels synthesized from polycondensation of two starting materials using sodium carbonate as the base catalyst. Successful formation of carbon aerogel was well confirmed by Fourier-transform infrared spectroscopy and $N_2$ adsorption-desorption analysis. Electrochemical performances of the assembled organic supercapacitor cells were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements. Amount of conductive additive was found to strongly affect the charge transfer resistance of the supercapacitor electrodes, leading to a different optimal amount of conductive additive in organic supercapacitor electrodes depending on the applied charge-discharge rate. A high-rate charge-discharge process required a relatively high amount of conductive additive. Through this work, we came to conclude that determining the optimal amount of conductive additive in developing an efficient organic supercapacitor should include a significant consideration of supercapacitor end use, especially the rate employed for the charge-discharge process.

• Analytical Science and Technology
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• v.8 no.4
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• pp.443-448
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• 1995

Three anode configurations of six-jet, cone-jet and cylindrical-jet are tested for their analytical performance under power mode operation. The effect of pressure, power and gas flow rate on atomic absorption signals have been studied. The increase of atomic absorption signal of sample element is observed at a fixed pressure in all configurations as the gas flow rate increase up to 300-600 seem, and as the power dissipated in the glow discharge cell increase. The lower the pressure is in the glow discharge cell at a fixed discharge power and argon flow rate, the greater the absorbance of sample element is. The optimum conditions are taken from these data and a calibration curve of Cu in low-alloy steel sample is obtained. In this calibration curve, six-jet configuration shows the best analytical results varies as the sample element.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1624-1626
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• 1999

PD in defect of solid insulation system is very harmful since It often leads to deterioration of insulation by the combined action of the discharge ions bombarding the surface and the action of chemical compounds that are formed by the discharge. PD can indicate incipient failure, so it has been used to determine degradation of insulation. In this paper. we investigated PD in defects of solid insulation by using statical method and classified PD patterns with surface discharge, electrical tree and void discharge by using Kohonen network. we used peak charge, average discharge power, average discharge current, repetition rate, skewness, kurtosis, QN of the max pulse height vs. repetition rate $H_q(n)$ for analysis and classification.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.92-96
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• 2000

In this experiment, we studied about concentration characteristics of $NO_x$ and generation of ozone in the reactor of corona discharge type by using mixed gas of $NO/N_2$ and $N_2/O_2$. In the case of the initial NO concentration increased, decrease rate of NO concentration was weakened and discharge input power of minimum NO concentration became high. When NO concentration was high, NO decomposition limit was appeared. And NO reduction rate was decreased, when initial NO concentration and discharge input power increased. When discharge input power was 5W, we could know the most proper energy value for treatment of NO. When the concentration of initial NO increased, generation of ozone decreased and in the case of same concentration of NO, according to discharge input power increase, generation of ozone increased.