• Membrane and Water Treatment
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• 제2권3호
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• pp.187-205
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• 2011

The electric transport of the mixture of hydrochloric and phosphoric acids through strong base (Neosepta ACM) and weak base (Selemion AAV) anion-exchange membranes was investigated. The instantaneous efficiency of HCl removal from the cathode solution, $CE_{Cl}$, with and without $H_3PO_4$ was determined. It was found that $CE_{Cl}$ was 0.8-0.9 if the number of moles of elementary charge passed through the system, $n_F$, did not exceed ca. 80% of the initial number of HCl moles in the cathode solution, $n_{Cl,ca,0}$. The retention efficiency of $H_3PO_4$ in that range was close to one. The transport of acid mixtures was satisfactorily described by a model based on the extended Nernst-Planck and Donnan equations for $n_F$ not exceeding $n_{Cl,ca,0}$. Among the tested model parameters, most important were: concentration of fixed charges, the porosity-tortuosity coefficient, and the partition coefficient of an undissociated form of $H_3PO_4$. For the both membranes, the obtained optimal values of fixed charge concentration, $\bar{c}_m$, were up to 40% lower than the literature values of $\bar{c}_m$ obtained from the equilibrium measurements. Regarding the $H_3PO_4$ equilibria, it was sufficient to consider $H_3PO_4$ as a monoprotic acid.

• Nuclear Engineering and Technology
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• 제46권3호
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• pp.387-394
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• 2014

A Slowing Down Time Spectrometer (SDTS) system is a highly efficient technique for isotopic nuclear material content analysis. SDTS technology has been used to analyze spent nuclear fuel and the pyro-processing of spent fuel. SDTS requires an external neutron source to induce the isotopic fissile fission. A high intensity neutron source is required to ensure a high for a good fissile fission. The electron linear accelerator system was selected to generate proper source neutrons efficiently. As a first step, the electron generator of an 80-keV electron gun was manufactured. In order to produce the high beam power from electron linear accelerator, a proper beam current is required form the electron generator. In this study, the beam current was measured by evaluating the performance of the electron generator. The beam current was determined by five parameters: high voltage at the electron gun, cathode voltage, pulse width, pulse amplitude, and bias voltage at the grid. From the experimental results under optimal conditions, the high voltage was determined to be 80 kV, the pulse width was 500 ns, and the cathode voltage was from 4.2 V to 4.6 V. The beam current was measured as 1.9 A at maximum. These results satisfy the beam current required for the operation of an electron linear accelerator.

• KSBB Journal
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• 제13권1호
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• pp.52-57
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• 1998

The present work proposes a simple electrochemical method applicable to any immobilization processes of oxidase using a Clark type oxygen electrode as a base transducer. The present work suggests an optimal immobilization technique among three different methods of glucose oxidase(GOD) onto one side of $37[\mu}$mthick blend membranes, composed o 80% of cellulose triacetate and 20% of polycaprolactone, on the basis of the maximum Michaelis-Menten parameter(Vm) determined by either steady state or transient analyses. The electrode system was made of disk type gold cathode(4mm diameter) and Ag/AgCl anode. One side of the blend membrane was in contact with the cathode surface while the other side was immobilized with GOD either in covalent-bond or cross-linked forms, the latter being covered by $25{\mu}$m thick dialysis membrane of cellulose acetate. The resultant current density was on-line monitored by a potentiostat while glucose level was varied from 1 to 20 mM. The present study shows that direct cross-linking of GOD with glutaraldehyde was mostly preferred for fabrication of glucose sensor, on the basis of resultant kinetic parameters from either steady state or transient analyses.

• 한국세라믹학회지
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• 제55권1호
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• pp.21-35
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• 2018

Spinel $LiNi_{0.5}Mn_{1.5}O_4$ has received great attention as one of the most outstanding cathode materials for Li-ion batteries (LIBs) because of its high energy density resulting from the operating voltage of ~ 4.7 V (vs. $Li^+/Li$) based on the $Ni^{2+}/Ni^{4+}$ redox reaction. However, $LiNi_{0.5}Mn_{1.5}O_4$ is known to suffer from undesirable side reactions with the electrolyte at high voltage as well as Mn dissolution from the structure. These issues prevent the realization of the optimal electrochemical performance of $LiNi_{0.5}Mn_{1.5}O_4$. Extensive research has been conducted to overcome these issues. This review presents an overview of the various surface-modification methods available to improve the electrochemical properties of $LiNi_{0.5}Mn_{1.5}O_4$ and provides perspectives on further research aimed at the application of $LiNi_{0.5}Mn_{1.5}O_4$ as a cathode material in commercialized LIBs.

• 한국가시화정보학회지
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• 제20권2호
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• pp.13-20
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• 2022

An effective capacitive deionization process termed membrane capacitive deionization (MCDI) is newly designed and experimentally tested for seawater desalination. By preventing co-ions to be expelled, MCDI can improve the ion removal performance, but there is a trade-off between blocking co-ion transfer and increasing contact resistance. The conventional MCDI uses 2D-shaped films which increase contact resistance and reduce desalination performance in the trade-off. In this paper, with the 3-D shape of Nafion coated activated carbon cloth, the mentioned problems are expected to be solved making the desalination performance better. We visualized ion concentration and fluid flows with half-MCDI cell that can measure only efficiency of cathode. We found the optimal number of coatings which have the better efficiency than CMX, commercial cation exchange membrane in fixed current conditions of 100uA.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.292-300
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• 2024

Kinetic simulations have been performed on an Inertial Electrostatic Confinement Fusion (IECF) device. These simulations were performed using the particle-in-cell (PIC) method to analyze the behavior of ions in an IEC device and the effects of some parameters on the Confinement Time (CT). CT is an essential factor that significantly contributes to the IEC's performance as a nuclear fusion device. Using the PIC method, the geometry of a two-grided device with variable grid radius, the number of cathode grid rings, variable pressure and different dielectric thickness for the feed stalk was simulated. In this research, with the development of previous works, the interaction of particles was simulated and compared with previous results. The simulation results are in good agreement with the previous results. In these simulations, it was found that with the increase of the dielectric thickness of the feed stalk, the electric field was weakened and as a result, the confinement time was reduced. On the other hand, with the increase of the cathode radius, the confinement time increased. Using the results, an IEC device can be designed with higher efficiency and more optimal CT for ions.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1471-1480
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• 2020

This research presents a case study on the remediation of a radioactive waste (uranium: U) utilizing a multi-objective fuzzy optimization in an electrocoagulation process for the iron-stainless steel and aluminum-stainless steel anode/cathode systems. The incorporation of the cumulative uncertainty of result, operational cost and energy consumption are essential key elements in determining the feasibility of the developed model equations in satisfying specific maximum contaminant level (MCL) required by stringent environmental regulations worldwide. Pareto-optimal solutions showed that the iron system (0 ㎍/L U: 492 USD/g-U) outperformed the aluminum system (96 ㎍/L U: 747 USD/g-U) in terms of the retained uranium concentration and energy consumption. Thus, the iron system was further carried out in a multi-objective analysis due to its feasibility in satisfying various uranium standard regulatory limits. Based on the 30 ㎍/L MCL, the decision-making process via fuzzy logic showed an overall satisfaction of 6.1% at a treatment time and current density of 101.6 min and 59.9 mA/㎠, respectively. The fuzzy optimal solution reveals the following: uranium concentration - 5 ㎍/L, cumulative uncertainty - 25 ㎍/L, energy consumption - 461.7 kWh/g-U and operational cost based on electricity cost in the United States - 60.0 USD/g-U, South Korea - 55.4 USD/g-U and Finland - 78.5 USD/g-U.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.122-122
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• 2010

A Static Induction Thyristor (SI-Thyristor) has a great potential as power semiconductor switch for pulsed power or high voltage applications with fast turn-on switching time and high switching stress endurance (di/dt, dV/dt). However, due to direct commutation between gate driver and SI-Thyristor, it is difficult to design optimal gate driver at the aspect of impedance matching for fast gate current driving into internal SI-Thyristor. Thus, to penetrate fast positive gate current into steady off state of the SI-Thyristor, it is proposed and proceeded the internal impedance calculation of the SI-Thyristor at steady off state with the gate driver while switching conditions that are indicated applied gate voltage, $V_{GK}$ and applied high voltage across anode and cathode, $V_{AK}$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1061-1065
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• 1995

To improve dielectric and mechanical properties of insulating composite by plasma surface treatment, new plasma surface treatment process is designed with concentric and hemi-circle electrodes system, the plasma, which is generated between anode and cathode, is induced to the upper side of the electrode system and treats the surface of the insulators. The optimal surface treatment condition is that pressure : 0.5[torr], flux density 100[gauss], discharge current : 500[mA] and treatment time : 3 minutes. The composite filled with glass cloth surface-treated by plasma shows the improvement in electric and mechanical properties, comparing non- and coupling agent-treated samples.

• 한국생산제조학회지
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• 제21권4호
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• pp.547-555
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• 2012

This paper focuses on the research of the anode and cathode in the Ni-MH secondary battery. In this paper, the proposed method employs a continuous wave Nd : YAG laser based on the pure Ni instead of the low carbon steel to improve the conductivity although the conventional secondary battery is based on the resistance spot welded with low carbon steel SS41. It welds a sandwich panel using the pure Ni and the porous thin plate, and the tested optimal conditions for the laser power and irradiation speed were 300 and 350 Watt, and 1.0~1.6m/min, respectively. Finally, we observed a ratio, heat input and cross-section and measured the conductivity of the welding section to test the weldability.