• Journal of Korean Society of Transportation
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• v.35 no.3
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• pp.210-219
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• 2017

Electric vehicles, which are attracting attention as eco-friendly vehicles, have been increasing in number since 2011 in Korea. The purpose of this study is to analyze the efficient operation of existing charging stations and factors to consider when installing additional charging stations based on the case of Jeju Island where the electric vehicle penetration rate is high and the charging infrastructure is relatively well established. The characteristics of using electric car charging stations by region, type of facility, and time of day are analyzed. As a result of analyzing the frequency of using the charger installed in Jeju Island, the utilization of both the fast charger and the slow charger is found to be concentrated in a specific area. The usage rate of charger installed in a business facility and a public parking lot is high in both fast charger and slow charger. However, according to the usage rate by time of day, the fast charger has a high utilization rate throughout the afternoon, while the use of a slow charger is concentrated in the morning. In order to enable users to utilize the electric vehicle charging station efficiently, it is necessary to provide a publicity guide for the charging station having a low utilization rate, a notice for using the charger, and a notification of completion of charging. Considering the charging demand, the area where the charger is not yet installed should be considered as the area to install the charger, and in addition, the additional installation should be considered in the area and the facility where the amount of charge is large. Service improvement is expected to be possible by utilizing actual electric vehicle charging behavior analysis result.

• Journal of Power System Engineering
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• v.19 no.5
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• pp.60-66
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• 2015

Embrittlement of material by hydrogen charging should be cleared for safety of storage vessel of hydrogen and components deal with hydrogen. A stainless steel is generally used as materials for hydrogen transportation and storage, and it has a big advantage of corrosion resistance due to nickel component in material. In this study, microscopic damage behavior of stainless steel according to the hydrogen charging time using nondestructive evaluation was studied. The surface of stainless steel became more brittle as the hydrogen charging time increased. The parameters of nondestructive evaluation were also changed with the embrittlement of stainless steel surface by hydrogen charging. Ultrasonic test, which is the most generalized nondestructive technique, was applied to evaluate the relationship between the ultrasonic wave and mechanical properties of stainless steel by hydrogen charging. The attenuation coefficient of ultrasonic wave was increased with hydrogen charging time because of surface embrittlement of stainless steel. In addition, acoustic emission test was also used to study the dynamic behavior of stainless steel experienced hydrogen charging. AE event at the hydrogen charged specimen was obviously decreased at the plastic zone of stress-strain curves, while the number of event for the specimen of hydrogen free was dramatically generated when compared with the specimens underwent hydrogen charging.

• Macromolecular Research
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• v.8 no.1
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• pp.6-11
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• 2000

In this study, we examined the charging behavior of chopped carbon fibers during electro-flocking process, which is one of the key processes of the novel technique for fabricating conductive polymer composite films. Short carbon fibers (CF) during electroflocking were electrically charged by the combined effect of contact charging, corona charging and tribocharging. The specific charge built on CF surface was measured by using Faraday cup method. Specific charge increased not only with increasing electric field strength and potential impressed to mesh electrode as expected from theoretical considerations in literature, but with decreasing mesh opening size due to the improved contact charging condition. However, CF length was found unexpectedly to influence the amount of CF specific charge due to the agglomerated nature of CF flocks leading to the change in charging conditions.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.581-585
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• 2010

High strength sheet steels for automobile are seriously compromised by hydrogen embrittlement. This issue has been continuously studied, but the field of interest, which lies between microstructural characteristics and hydrogen behavior with hydrogen charging, has not yet been thoroughly investigated. This study was done to investigate the behavior of hydrogen according to the hydrogen volume fraction on 590MPa grade DP steels, which are developed under hydrogen charging conditions as high strength sheet steels for automobiles. The penetration depths and the mechanical properties, according to charging conditions, were investigated through the distribution of micro-hardness and the microstructural observation of the subsurface zone. It was found that the amount of hydrogen trapping in 590MPa DP steels was related to the austenite volume fraction. It was confirmed that the distribution of micro-hardnesses according to the depth of the subsurface zone under the free surface showed the relationship of the depth of the hydrogen saturation between the charging conditions.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.4
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• pp.340-345
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• 2010

For the conversion into hydrogen society, not only studying facilities of hydrogen production, storage, transportation and charging system but also developing technique of ensuring safety are essentially needed. Hence, for the first step of that, evaluated the hydrogen embrittlement of Inconel alloy 617, Ni-based super heat-resisting alloy, by small punch test. Prepared the various specimens through changing electrochemical charging time and measured the toughness degradation of the specimens by small-punch test. The analysis of hydrogen embrittlement behavior were carried out by investigating the fractured surface of specimens. This study has significance on revealing mechanism of hydrogen embrittlement behavior and the factor affecting hydrogen embrittlement in the future study.

• Korean Journal of Materials Research
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• v.31 no.2
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• pp.84-91
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• 2021

To cope with automobile exhaust gas regulations, ISG and charging control systems are applied to HEV vehicles for the purpose of improving fuel economy. These systems require quick charge-discharge performance of high current. Therefore, a Module of the AGM battery with high energy density and EDLC(Electric Double Layer Capacitor) with high power density are constructed to study the charging and discharging behavior. In CCA, which evaluates the starting performance at -18 ℃ & 30 ℃ with high current, EDLC contributed for about 8 sec at the beginning. At 0 ℃ CA (Charge Acceptance), the initial Charging current of the AGM/EDLC Module, is twice that of the AGM lead acid battery. To play the role of EDLC during high-current rapid charging and discharging, the condition of the AGM lead-acid battery is optimally maintained. As a result of a Standard of Battery Association of Japan (SBA) S0101 test, the service life of the Module of the AGM Lead Acid Battery/EDLC is found to improve by 2 times compared to that of the AGM Lead Acid Battery.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.3
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• pp.323-332
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• 1997

It was reported by some researchers that two-stage parallel-plate ESPs, commonly called electronic air cleaners, show decreasing behavior of collection efficiency as particle size decreases below about $0.03{\mu}m$. This phenomenon is attributed to partial particle charging characteristics, where some of incoming particles are not charged in the charging cell of 2-stage parallel-plate ESP. One way to improve the decreasing collection efficieny in that particle size range is to enforce particle charging quantity in the charging cell. In the present study, in order to do this a 2-wire series-type charging cell modified from a 1-wire normal-type one was suggested and investigated theoretically and experimentally concerning improvement of the collection efficiency. It was confirmed from the experimental and theoretical works that the collection efficiency was apparently improved.

• Journal of the Korean institute of surface engineering
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• v.46 no.5
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• pp.229-233
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• 2013

The small punch(SP) tests that can be applied to high strength sheet steel in automobile were carried out to evaluate the behavior of hydrogen embrittlement of DP sheet steels. In order to charge hydrogen at DP sheet steels, DP sheet steels were treated by the electrochemical hydrogen charging method under the charging conditions of current densities of 100, 150 and 200 $mA/cm^2$ for charging times of 5, 10, 25 and 50 hrs. Respectively, After hydrogen charging with experimental conditions, SP tests were performed. From the SP results, the correlations between the variation of bulb diameters and bulb heights with the hydrogen charging conditions were analysed. It was shown that the variation of bulb diameters were not significant with the hydrogen embrittlement due to the amounts of hydrogen charging. On the other hand, the bulb heights were observed to decrease with increasing hydrogen contents. It was thought that these results of the variation of bulb shapes after SP tests would be estimated as the index of evaluation of hydrogen embrittlement.

• Progress in Superconductivity and Cryogenics
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• v.20 no.4
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• pp.16-19
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• 2018

This paper presents analytical and numerical simulation approaches on charging characteristics of no-insulation (NI) REBCO pancake coil by using the equivalent circuit model to estimate magnetic performance response in the coil. The analytical methods provide closed form or definite solution in the form of complete mathematical expressions but they are hard to solve the complex problems. Numerical methods have become popular with the development of the computing capabilities to solve the problems which are impossible or very hard to solve analytically. First of all, the equivalent circuit model are proposed to develop the simulation code for both analytical and numerical method. The charging test was performed under critical current to obtain magnetic field induced and terminal voltage through the radial as well as spiral current paths within the coil. To verify the validity of both proposed methods, the simulation results were compared and discussed with the experimental results.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.4
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• pp.229-239
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• 2018

In this paper, we propose a strategy of charging by analyzing the difference of path coefficient according to whether consumers are free or not, rather than presenting strategies for charging. Mobile devices have become so popular that they are called necessities. Companies have to adapt to the mobile environment and respond to the situation, and have to expand market opportunities strategically. In this study, we extend the technology acceptance model to analyze the incentives of consumers' behavior by analyzing the difference in the effect consumers perceive as a moderating variable, whether paid or free. Efforts to maximize company's inherent profit continue, and in particular, charging is a strategy that all companies should pursue in the mobile environments. It is necessary to grasp the degree of the consumer's response to free and charge. The model of satisfaction with the continuous use and the word-of-mouth intention, which is the behavior intention, is presented by adding parameters of satisfaction to the technology acceptance model. In addition, we try to derive implications by analyzing the influence of moderating effects of whether free or not.