• Journal of the Korean institute of surface engineering
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• v.31 no.1
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• pp.24-33
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• 1998

Effects of pH and supporting salts on the characteristics of electrogalvanzied coating in sulfate bath are investigated. The fine grain size is obtained and the whiteness with the amount of supporting salts or pH increased at more than current density of 100A/$dm^2$<\TEX>, With supporting salts increased, the electro-conductivity of the bulk solution increases and the cell voltage decreases, while the width of the cathode burned edge gets wider because it seems that the increased overpotential the vicinity of cathode causes the decreases, of limiting current density. When the amount of supporting salts or pH of sulfate bath decreases, the zinc crystals have preferred orientation (001) planes. However when the amount of supporting salts or pH increase, the crystal texture has less (001) planes and gets to have random crystal planes.

• Clean Technology
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• v.10 no.2
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• pp.53-59
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• 2004

Direct methanol fuel cells (DMFC) are presently paid attention due to their higher energy density and portability. In order to slove problems such as high anodic overpotential and methanol crossover in DMFC, an analytical analysis for electrochemical model using Tafel equation and limiting current density was performed. Change of operational parameters such as temperature, transfer coefficients and membrane thickness results in helpful informations on voltage-current curves.

• Membrane and Water Treatment
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• v.7 no.4
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• pp.341-353
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• 2016

Papermaking reconstituted tobacco is an important strategy for recycling the waste tobacco residues. To indentify the influences of the inorganic components on harmful components delivery in cigarette smoke, a self-made electrodialysis stack was assembled to desalt the tobacco extract. The influences of the applied current and extract content on the removal rate of the inorganic ions were investigated. Results indicated that the applied current was a dominant impact on the desalination performance. High currents lower than the limiting current density could accelerate the desalting efficiency but cause higher energy consumption. A current of 2 A, or current density of ${\sim}11mA{\cdot}cm^{-2}$, was an optimal choice by considering both the energy consumption and desalting efficiency. A 20% tobacco extract was an appropriate content for the electrodialysis process. More than 90% of inorganic ions could be removed under the optimum condition. The preliminary result indicated that removal of inorganic components was beneficial to decrease the harmful component delivery in cigarette smoke. Naturally, ED is an environmentally friendly and high-effective technology for desalting the tobacco extract.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.334-340
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• 2017

A pilot-scale electrodialysis system was designed and constructed to treat groundwater polluted with arsenic and manganese. Synthetic groundwater, in which some amount of arsenic and manganese was added to make 500 mg/L of Mn and $50{\mu}g/L$ of As, was used as a feed for the ED system. The limiting current density, linear water velocity, applied voltage, and membrane surface area were investigated to obtain efficient and economic operation of the ED system. The linear water velocity was increased 0.74 cm/s to 11 cm/s based on evaluation of limiting current density. The water quality of diluate for 85 minutes of operation was satisfied with water quality criteria for drinking water using the ED system with 14 pairs of ion exchange membranes. The increased membrane pairs to 21 and 42 pairs were very effective to reduce conductivities of the diluate. The operation cost of the ED system was assessed using specific energy consumption, which was $1.065{\sim}1.2kWh/m^3$. Considering low salt concentrations of the groundwater, improvement of the ED system are required to increase current utilization and to apply low voltage while the ED system was applicable to produce drinking water.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.60-65
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• 2003

An effective modeling and simulation scheme of a resistive type Superconducting fault Current Limiter (SFCL) using PSCAD/EMTDC is proposed in this paper. In case of High Temperature Superconducting (HTS) resistive type fault current limiter current limiting is implemented by the ultra-fast transition characteristics from the superconducting (non-resistive) state to the normal (resistive) state by overstepping the critical current density. The states can generally be divided into three sub-states: the superconducting state the quench state and the recovery state respectively. In order to provide alternative application schemes of a resistive type SFCL, an effective modeling and simulation method of the SFCL is necessary. For that purpose, in this study, an actual experiment based component model is developed and applied for the simulation of the real resistive type SFCL using PSCAD/EMTDC. The proposed simulation scheme can be implemented to the grid system readily under various system conditions including sort of faults and the system capacity as well. The simulation results demonstrate the effectiveness of the proposed model and simulation scheme.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.201-210
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• 2017

We investigated the effect of applied voltage and electrolyte concentration on the nitrate removal and its energy/current efficiency during the electrodialysis. The current increased as the applied voltage increased up to 30 V showing the limiting current density around 20 V. The nitrate removal efficiency (31 to 71% in 240 min) and energy consumption (11 to $77W{\cdot}h/L$) gradually increased as the applied voltage increased from 10 to 30 V. The highest current efficiency was obtained at 20 V. The increase in electrolyte concentration from 100 to 500 mM led to the dramatic increase of nitrate removal efficiency with much faster removal kinetics (100 % in 10 min).

• Advances in Energy Research
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• v.1 no.1
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• pp.35-52
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• 2013

A model for DMFC anode performance is developed. The model takes into account potential--independent methanol adsorption on the catalyst surface, finite rate of proton transport through the anode catalyst layer (ACL), and a potential loss due to methanol transport in the anode backing layer. An approximate analytical half--cell polarization curve is derived and equations for the anode limiting current density are obtained. The polarization curve is fitted to the curves measured by Nordlund and Lindbergh and parameters resulted from the fitting are discussed.

• Proceedings of the Membrane Society of Korea Conference
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• 2002.05a
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• pp.134-137
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• 2002

No Abstract, See Full-text

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.271-282
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• 2019

The span record of cable-stayed bridges has exceeded 1,000 m, which makes research on the maximum possible span length of cable-stayed bridges an important topic in the engineering community. In this paper, span limit is discussed from two perspectives: the theoretical span limit determined by the strength-to-density ratio of the cable and girder, and the engineering span limit, which depends not only on the strength-to-density ratio of materials but also on the actual loading conditions. Closed form equations of both theoretical and engineering span limits of cable-stayed bridges determined by the cable and girder are derived and a detailed parametric analysis is conducted to assess the engineering span limit under current technical conditions. The results show that the engineering span limit of cable-stayed bridges is about 2,200 m based on materials used available today. The girder is the critical member restricting further increase in the span length; its compressive stress is the limiting factor. Approaches to increasing the engineering span limit are also presented based on the analysis results.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.927-933
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• 1997

The effects of carbon black on the electrodes performance and on the structure of the catalyst layer in Raney nickel hydrogen electrodes for alkaline fuel cells were investigated by using electrochemical and nitrogen adsorption methods. The optimum content of carbon black in the catalyst layer of Raney nickel hydrogen electrode was 2wt%. The limiting current density was increased by the addition of carbon black due to the enlargement of gas-liquid interface area. The rate determining step at the limiting current density was supposed to be a step where hydrogen dissolves at gas-liquid interfaces.