• Nuclear Engineering and Technology
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• 제35권3호
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• pp.226-233
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• 2003

The discharge characteristics of a prototype ion source was investigated, which was developed and upgraded for the NBI (Neutral Beam Injection) heating system of KSTAR (Korea Superconducting Tokamak Advanced Research). The ion source was designed for the arc discharge of magnetic bucket chamber with multi-pole cusp fields. The ion source was discharged by the emission-limited mode with the control of filament heating voltage. The maximum ion density was 4 times larger than the previous discharge controlled by a space-charge-limited mode with fully heated filament. The plasma (ion) density and arc current were proportional to the filament voltage, but the discharge efficiency was inversely proportional to the operating pressure of hydrogen gas. The maximum ion density and arc current were obtained with constant arc voltage ($80{\sim}100V$), as $8{\times}10^{11}cm^{-3}$ and 1200 A, respectively. The estimated maximum beam current was about 35 A, extracted by the accelerating voltage of 80kV.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권5호
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• pp.231-238
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• 2006

This paper analysed the induced current density inside human body of hot-line worker for 765kV double circuit transmission line according to locations of human body. Human model was composed of several organs and other parts, whose shapes were expressed by spheroids or cylinders. Organs such as the brain, heart, lungs, liver and intestines were taken into account. Applying the 3 dimensional boundary element method, we calculated induced current density in case a worker was located inside and outside a lowest phase of 765 kV transmission line in which a 60% current of maximum load flowed. As results of study, we found a maximum induced current density in all organs was less than $10mA/m^2$ when a wonder was outside. As one in brain and heart was higher than $10mA/m^2$ when a worker was inside, we propose a method for lowering current density.

• 대한기계학회논문집B
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• 제40권12호
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• pp.777-784
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• 2016

바나듐 전해질 산화-환원 흐름전지(vanadium redox flow batteries, VRFBs)는 간헐적 에너지 저장 시스템의 에너지 저장장치로 사용된다. VRFBs는 재료 및 동작조건에 따라 성능의 차이를 보이며, 각 성능특성에 따른 VRFBs개발이 요구된다. 본 연구에 사용된 단위셀은 반응면적 $25cm^2$이며, 전해액은 0.6의 충전상태를 나타낸다. 방전전류밀도를 0에서 $520mA/cm^2$ 까지 변화시키면서 동시에 전해질 유량도 5mL/min에서 60mL/min까지 변화시켰다. 동일한 입구 전해액 상태에 따른 방전 성능 평가를 위해 4개의 탱크를 사용한 비순환 시스템을 구축하였다. 본 논문은 유량 및 전류밀도의 변화에 대한 단자전압을 측정하였으며, $25cm^2$ 반응면적을 가지는 바나듐계 산화-환원 유동전지 시스템의 최대전류밀도에 대한 실험식을 도출하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제1권1호
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• pp.22-27
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• 1999

Recently, small-sized superconducting magnetic storage($\mu$SMES) coils become commercially as an energy storage device for a power conditioner. In design and fabrication of the $\mu$SMES coils, to determine optimum current capacity of the superconducting(SC) conductors is one of the important things. We thus investigated the effect of conductor's current capacity, current density, and stability on the coil's maximum stored energy density in consideration of AC losses and switching device's capacities in a power converter. The results show that the smaller current capacity of the SC conductors is preferred for the $\mu$SMES coils but can increase their induced voltage excessively.

• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.38-57
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• 2021

The different weight ratios of Pd to Pt, i.e., 16:4, 10:10, 4:16 in Pd-Pt/C and Pd (20 wt. %) /C electrocatalysts with low metal loading were synthesized for glycerol electrooxidation in an air breathing microfluidic fuel cell (MFC). The cell performance on Pd-Pt (16:4)/C anode electrocatalyst was found best among all the electrocatalysts tested. The single cell when tested at a temperature of 35℃ using Pd-Pt (16:4)/C, showed maximum open circuit voltage (OCV) of 0.70 V and maximum power density of 2.77 mW/㎠ at a current density of 7.71 mA/㎠. The power density increased 1.45 times when cell temperature was raised from 35℃ to 75℃. The maximum OCV of 0.78 V and the maximum power density of 4.03 mW/㎠ at a current density of 10.47 mA/㎠ were observed at the temperature of 75℃. The results of CV substantiate the single cell performance for various operating parameters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1055-1056
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• 2011

This paper deals with optimum design criteria for maximum torque density & minimum current density of a single phase line-start permanent-magnet motor (LSPMM) using RSM (Response Surface Methodology) & FEM (Finite Element Method). The focus of this paper is to find a design solution through the comparison of torque density and minimum current density resulting from rotor shape variations. And then, a central composite design (CCD) mixed resolution is introduced, and analysis of variance (ANOVA) is conducted to determine the significance of the fitted regression model.

• Environmental Engineering Research
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• 제22권2호
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• pp.141-148
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• 2017

Globalization, industrialization, mining, and uncontrolled population growth have fostered a shortage of potable water. Therefore, it has become imperative to understand an effective and reasonable water purification technique. A renewed interest in electrocoagulation (EC) has been spurred by the search for reliable, cost-effective, water-treatment processes. This paper has elucidated a technical approach for getting rid of heavy metals and total suspended solids (TSS) from synthetic water using an aluminum electrode. The effect of operational parameters, such as current density, inter-electrode distance, operating time, and pH, were studied and evaluated for maximum efficiency. This study corroborates the correlation between current density and removal efficiency. Neutral pH and a low electrode gap have been found to aid the efficacy of the EC setup. The outcome indicates that a maximum TSS removal efficiency of 76.6% occurred at a current density of $5.3mA/cm^2$ during a contact time of 30 min. In the case of heavy metals remediation, 40 min of process time exhibited extremely reduced rates of 99%, 59.2%, and 82.1%, for Cu, Cr, and Zn, respectively. Moreover, kinetic study has also demonstrated that pollutants removal follows first-and second-order model with current density and EC time being dependent.

• Journal of Electrochemical Science and Technology
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• 제13권2호
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• pp.292-307
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• 2022

The study presents kinetics of degradation and mineralization of an anti-epileptic drug Lamotrigine (LAM) in the aqueous matrix by electrochemical advanced oxidation process (EAOP) on Ti/DSA (Ta₂O₅-Ir₂O₅) and Stainless Steel (SS) anodes using sodium sulphate as supporting electrolyte. On both the anodes, kinetic behaviour was pseudo-first-order for degradation as well as mineralization of LAM. On Ti/DSA anode, maximum LAM degradation of 75.42% was observed at an associated specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm² and 100 ppm Na₂SO₄ concentration. Maximum mineralization attained was 44.83% at an associated specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm² and 50 ppm concentration of Na₂SO₄ with energy consumption of 2942.71 kWh/kgTOC. Under identical conditions on SS anode, a maximum of 98.92% LAM degradation was marked after a specific charge (Q) of 3.1 (Ah/litre) at a current density of 1.38 mA/cm² and 100 ppm concentration of Na₂SO₄. Maximum LAM mineralization on SS anode was 98.53%, marked at a specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm² and 75 ppm concentration of Na₂SO₄, with energy consumption of 1312.17 kWh/kgTOC. Higher Mineralization Current Efficiency (MCE) values were attained for EAOP on SS anode for both degradation and mineralization due to occurrence of combined electro-oxidation and electro-coagulation process in comparison to EAOP on Ti/DSA anode due to occurrence of lone electro-oxidation process.

• Computers and Concrete
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• 제32권3호
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• pp.287-302
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• 2023

Corrosion of reinforcing bars in reinforced concrete structures due to chloride attack in environments containing chloride ions is one of the most important factors in the destruction of concrete structures. According to the abundant reports that the corrosion rate around the repair area has increased due to the macro-cell current known as the incipient anode, it is necessary to understand the effective parameters. The main objective of this paper is to investigate the effect of the kinetic parameters of corrosion including the cathodic Tafel slope, exchange current density, and equilibrium potential in repair materials on the total corrosion rate and maximum corrosion rate in the patch repair system. With the numerical simulation of the patch repair system and concerning the effect of parameters such as electromotive force (substrate concrete activity level), length of repair area, and resistivity of substrate and repair concrete, and with constant other parameters, the sensitivity of the macro-cell current caused by changes in the kinetic parameters of corrosion of the repairing materials has been investigated. The results show that the maximum effect on the macro-cell current values occurred with the change of cathodic Tafel slope, and the effect change of exchange current density and the equilibrium potential is almost the same. In the low repair extant and low resistivity of the repairing materials, with the increase in the electromotive force (degree of substrate concrete activity) of the patch repair system, the sensitivity of the total corrosion current reduces with the reduction in the cathode Tafel slope. The overall corrosion current will be very sensitive to changes in the kinetic parameters of corrosion. The change in the cathodic Tafel slope from 0.16 to 0.12 V/dec and in 300 mV the electromotive force will translate into an increase of 200% of the total corrosion current. While the percentage of this change in currency density and equilibrium potential is 53 and 43 percent, respectively. Moreover, by increasing the electro-motive force, the sensitivity of the total corrosion current decreases or becomes constant. The maximum corrosion does not change significantly based on the modification of the corrosion kinetic parameters and the modification will not affect the maximum corrosion in the repair system. Given that the macro-cell current in addition to the repair geometry is influenced by the sections of reactions of cathodic, anodic, and ohmic drop in repair and base concrete materials, in different parameters depending on the dominance of each section, the sensitivity of the total current and maximum corrosion in each scenario will be different.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1243-1244
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• 2006

Five kinds of double stacked 385 (55 x7) filamentary Bi2212/Ag round wires and 55 filamentary tapes with different Ag ratios (silver area/superconductor area) have been fabricated via PIT method, and the effects of Ag ratio and processing factors on critical current density were studied. The effects of the maximum temperature and average filament diameter on critical current density were also studied. The wire of 0.74 mm diameter having Ag ratio 3.7 showed critical current density of $2,218\;A/mm^2$ at 4.2 K, 0 T.