• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.54-59
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• 2003

The discharge energy by electrostatic discharge of the charged human body is calculated under the assumption that the stored charge is dissipated completely. However, it is well-known that the charge is slightly remained after electrostatic discharge. Therefore, The Rompe-Weisel model of the discharge analysis, which has somewhat more of a physical justification than the conventional energy equation, is proposed. It is proposed that the electrical conductivity of the arc should be proportional to the energy density transferred to it by Ohmic dissipation. For the electrostatic discharge energy analysis, the Rompe-Weisel model was compared by quasi static analysis. As a consequence, a study on a reliable energy evaluation based on simulation models during electrostatic discharge is carried out in this paper and is adopted to estimate the explosion hazards of flammable gases.

• Journal of the Korean Society of Safety
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• v.39 no.2
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• pp.1-8
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• 2024

Unwanted effects of electrostatic phenomena occur in various industries. Electrostatic problems originating from the human body in flammable atmospheres in the industry are especially concerning. A substantial volume of experimental data on the electrostatic charging voltages created on the human body owing to the rubbing of apparel were generated and reviewed during this study. The data were reviewed to determine whether the resultant charging levels of the human body are hazardous in flammable atmospheres. This study was conducted under several conditions, such as different fiber types used in apparel, shoe types, and relative humidities (RHs). The following conclusions were drawn in this study. ① The electrostatic charging levels of the human body owing to the rubbing of apparel increase with the increase in the surface resistances of apparel; however, the electrostatic charging levels may be different depending on the condition of the cloth surface. ② The discharging energy of 1.98-18.5 [mJ] from the human body exceeds the minimum ignition energy of most flammable materials, when removing an overcoat made of polyester, cotton and wool under severe conditions such as wearing height-raising shoes for men. ③ When removing antistatic apparel, the maximum discharging energy of 0.128 mJ from the human body is dangerous if the minimum ignition energy of the flammable material is between 10^-5-10^-4 [J] Grade; however, a minimum ignition energy of 10^-3 J Grade of the flammable material is considered safe. ④ While wearing antistatic shoes, the electrostatic charging voltage generated in the human body when removing an overcoat is 30 V; therefore, wearing such shoes is a suitable countermeasure when handling flammable materials. However, the antistatic abilities of shoes reduce when thick socks are worn. ⑤ As RH increases, the electrostatic charging levels of the human body decrease. ⑥ The electrostatic charging levels of the human body from removing a cotton overcoat can ignite the majority of flammable materials when RH is less than 30% under severe conditions such as wearing height-raising shoes for men.

• Journal of the Korean Society of Safety
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• v.25 no.4
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• pp.19-24
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• 2010

A large amount of electrostatic charges is often generated on polymer powders in fluidized bed and thereby may lead to electrostatic problems. In this study, to evaluate electrostatic hazards of powder in fluidized bed, the electric field(E[v/m]) and the charge amount(q[c/g]) during fluidizing were monitored. We also investigated the Minimum Ignition Energy(MIE [J]) of sample powder used in fluidized bed with the Hartman vertical-tube apparatus. The batch-type fluidized bed system and 2kg as Polypropylene(PP) resin powders were used in the experiments. The following results were obtained: (1) Even when a safe margin of several times was considered, the values of E obtained with PP powder in this paper did not exceed 3 to 5kV/cm, at which an incendiary electrostatic discharge could occur. (2) the ave. q was -0.26${\mu}$C/g during fluidizing. This value was high enough to cause electrostatic agglomeration and adhesion. (3) the entrained PP powder in upper column due to fluidizing could be ignited by electrostatic discharges of 71mJ.

• Journal of Photoscience
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• v.8 no.1
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• pp.33-37
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• 2001

Picosecond absorption spectroscopy has been employed in the study of the solvent dynamics of 1, 2, 4, 5-tetracyanobenzene/biphenyl derivative radical ion pairs, and the resulting rates of radical ion pair separation are faster in acetonitrile than in dichloromethane. In an effort to account quantitatively for such solvent effect on the rate of radical ion pair separation, an equation for the rate of radical ion pair separation is introduced, in which the rate depends exponentially on the electrostatic interaction energy in the radical ion pair. In our analysis of the types of electrostatic interaction energy based on the conducting spheres in dielectric continuum was chosen, and the rate equation employing this electrostatic energy provided information on the distance on the distance of radical ion pair separation and solvation energy of the radical ion pair, thereby providing quantitative explanation for the observed solvent effect on the rate of radical ion pair sepaaration.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.6-13
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• 2022

The electrostatic phenomenon seriously issued in extreme ultraviolet semiconductor cleaning was studied in junction with molecular dynamic aspect. It was understood that two lone pairs of electrons in water molecule were subtly different each other in molecular orbital symmetry, existed as two states of large energy difference, and became basis for water clustering through hydron bonds. It was deduced that when hydrogen bond formed by lone pair of higher energy state was broken, two types of [H₂O]⁺ and [H₂O]^- ions would be instantaneously generated, or that lone pair of higher energy state experiencing reactions such as friction with Teflon surface could cause electrostatic generation. It was specifically observed that, in case of electrolyzed cathode water, negative electrostatic charges by electrons were overlapped with negative oxidation reduction potentials without mutual reaction. Therefore, it seemed that negative electrostatic development could be minimized in cathode water by mutual repulsion of electrons and [OH]^- ions, which would be providing excellences on extreme ultraviolet cleaning and electrostatic control as well.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.563-564
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• 2010

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.15-22
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• 2011

Explosion and fire cause about 30 reported industrial major accidents a year by ignition source which discharge of electrostatic generated to flammable gas, vapor, dust and mixtures. It brings economically and humanly very large loss that accident was caused by fire and explosion from electrostatic discharge. Thus, it is very important that electrostatic discharge energy is to be control below not to be igniting flammable mixtures. There are two kinds of analysis model for electrostatic discharge, human body model and machine model. Human body model is available the parameter of human's electrical equivalent that capacitance is 100 pF, resistance is $1.5k{\Omega}$. To simulate and visualize the electrostatic discharge from human body need a very expensive and high voltage simulator. In this paper, we measured the value of capacitance and resistance concerned with test materials and sizing of specimen and the value of charged voltage concerned with test specimen and distance to develop an electrostatic charge/discharge simulating tool for teaching with which concerned industrial employee and students. The result of experiments, we conformed that the minimum ignition energy of methane-oxygen mixtures meets well the equation $W=1/2CV^2$, and found out that the insulating material and sizing of equivalent value having human body mode are the poly ethylene of 200 mm and 300 mm of diameter. Developed electrostatic charge/discharge simulating tool has many merits; simple mechanism, low cost, no need of electric power and so on.

• Plant Journal
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• v.16 no.1
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• pp.34-37
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• 2020

The need to improve the performance of the dust collector by increasing the fine dust pollution in Korea is eminent. In this study, electrostatic spray wet electrostatic precipitator is used to remove Particulate Matter (PM). In order to enter the Cone-jet mode, which is the most stable spray mode among the various modes of electrostatic spraying, an appropriate voltage-flow condition must be satisfied, and a voltage-flow interval enabling this can be expressed as Stability Island. The voltage at which the conduit mode starts in the Stability Island section is referred to as the electrostatic spray minimum voltage (Onset Voltage). However, the conventional electrostatic spray is uses a very low flowrate, at most few millilitres per minute. The use of much higher flowrates has introduced different patterns of electrospray modes. In this study, the different spray modes will be studied in detail.

• Journal of Energy Engineering
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• v.12 no.3
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• pp.207-215
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• 2003

An experimental study on the characteristics of collection efficiency for electrostatic precipitator under the action of acoustic energy in the gas stream was performed. In the experiment, the acoustic energy which has 2 kHz and 141 dB was applied to electrostatic precipitator inlet, and the test parameters were used in terms of the magnitude of gas velocity. From the results of experiment, the collection efficiency of ESP was increased due to acoustic energy, and this effect was much clearer at high velocity. This means that the acoustic energy can play an important role in the enlargement of specific collection area of the electrostatic precipitator.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.29-34
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• 2013

When flammable gases are mixed with air or oxygen in the explosion concentration range and are ignited by sufficiently large electrostatic discharge energy, they may explode causing severe disaster in workplace. The minimum ignition energy(MIE) of single gas-air mixtures has been already investigated by many research, but the MIE of mixtures of more than ternary gas mixture is not examined yet. The purpose of this study is to investigate the MIE of a ternary gas(methane, ethylene, hydrogen, propane) mixtures experimentally. The results of our experiment show that the ignition of a methane-ethylene-air, methane-hydrogen-air, methane-propane-air, ethylene-hydrogen-air, ethylene-propane-air and hydrogen-propane-air mixture due to electrostatic discharge energy primarily depends on that the mixture: the MIE decreases gradually with the increase of having the lower MIE than other mixture ratio in the normal atmospheric pressure.