• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.401-405
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• 2012

Current research about voltage leakage involves investigation of the effects of leaked voltage and current on humans through simulated environments and dummies. Electrocution results from leaked current when electricity flows through the body as a result of potential difference. Research that analyzes actual electrocution is insufficient because of the danger from leaked voltage present in the leakage area. This thesis analyzes magnetic flux density from current around a leak to investigate the distribution of current. The authors used a simulated environment to investigate electrocution accidents that frequently occur during floods through leakage along metal surfaces, and evaluated the distribution of leaked magnetic flux.

• 전기의세계
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• 제22권5호
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• pp.19-32
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• 1973

This paper treats with some of plasma jet behaviors under magnetic field for the purpose of controlling important characteristics of plasma jet in the practices of material manufacturings. Under the existence and non-existence of magnetic field, the pressure distribution, flame length, stability and noise of plasma jet are comparatively evaluated in respect of such parameters as are current, gap of electrode, quantity of argon flow, magnetic flux density, diameter and length of nozzle. The results are as follows: 1) the pressure, the length and the noise of plasma jet rise gradually with the increase of are current, and have high values under identical arc current as the diameter of nozzle increases, but reverse phenomenon tends to appear in the noise. 2) The pressure, the flame length and the noise increase with the increased quantity of argon flow, and the rising slope of noise is particularly steep. Under magnetic field, the quantity of argon flow in respect of flame length has the critical value of 80(cfh). 3) The pressure and length of flame decrease with small gradient value as the length of gap increases, but the noise tends to grow according to the increase of nozzle diameter. 4) The pressure and the length of jet flame decrease inversly with the increase of magnetic flux density, which have one critical value in the 100 amps of arc current and two values in 50 amps. The pressure of jet flame can be below atomospher pressure in strong magnetic field. 5) "The constriction length of nozzle has respectively the critical value of 6(mm) for pressure and 23(mm) for the length of flame. 6) Fluctuations in the wave form of voltage become greater with the increase of argon flow and magnetic flux density, but tends to decrease as arc current increases, having the frequency range of 3-8KHz. The wave form of noise changes almost in parallel with that of voltage and its changing value increases with argon flow, arc current and magnetic flux density, having the freuqency range of 6-8KHz. The fluctuation of jet presurre is reduced with the increase of argon flow and magnetic flux density and grows with arc current.rent.

• 대한의용생체공학회:의공학회지
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• 제30권6호
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• pp.461-468
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• 2009

Magnetic resonance electrical impedance tomography (MREIT) enables us to perform high-resolution conductivity imaging of an electrically conducting object. Injecting low-frequency current through a pair of surface electrodes, we measure an induced magnetic flux density using an MRI scanner and this requires a sophisticated MR phase imaging method. Applying a conductivity image reconstruction algorithm to measured magnetic flux density data subject to multiple injection currents, we can produce multi-slice cross-sectional conductivity images. When there exists a local region of fat, the well-known chemical shift phenomenon produces misalignments of pixels in MR images. This may result in artifacts in magnetic flux density image and consequently in conductivity image. In this paper, we investigate chemical shift artifact correction in MREIT based on the well-known three-point Dixon technique. The major difference is in the fact that we must focus on the phase image in MREIT. Using three Dixon data sets, we explain how to calculate a magnetic flux density image without chemical shift artifact. We test the correction method through imaging experiments of a cheese phantom and postmortem canine head. Experimental results clearly show that the method effectively eliminates artifacts related with the chemical shift phenomenon in a reconstructed conductivity image.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.179-188
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• 2003

The spray characteristics of dual orifice injector were investigated under two different fuels through measurement of SMD, number density and volume flux by using PDPA system. In this experiment, we found out that the droplet size and spray structure are strongly depend on fuel density and viscosity.

• Journal of Pharmaceutical Investigation
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• 제34권6호
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• pp.491-497
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• 2004

We investigated some important factors which affect the transdermal flux of ketoprofen, a nonsteroidal anti-inflammatory agent, as a first step to provide some basic knowledge for the development of a iontophoretic transdermal patch system. Factors such as current density, polarity, buffer (HEPES) and electrolyte concentration and pH were studied using hairless mouse skin. The effect of poly(L-lysin), which is known to affect the electro-osmotic flow through skin, on flux was also studied. Passive flux was about $20\;{\mu}g/cm^2hr$ at pH 4.0, but was negligible at pH 7.4 where all ketoprofen molecules dissolved are ionized (ketoprofen pKa=5.94). At pH 4.0, application of anodal current increased the flux further above the passive level, however anodal flux at pH 7.4 was much smaller than passive flux at pH 4.0. The application of cathodal current at pH 4.0 increased the average flux to $30-40\;{\mu}g/cm^2hr$, depending on the current density applied. At pH 7.4, cathodal flux was only about $5\;{\mu}g/cm^2hr$. Decrease in buffer and electrolyte concentration increased this cathodal flux about 10 fold. However decrease in HEPES buffer concentration 100 fold did not affect the flux. Anodal flux of acetaminophen was much larger than cathodal flux, indicating that electroosmotic flow can be playing an important role in the flux. Poly(L-lysin) increased the cathodal flux at pH 7.4. These results provide some important insights into the mechanism of transdermal flux of ketoprofen and the role of electroosmotic flow.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제20회 KOSCO SYMPOSIUM 논문집
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• pp.122-132
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• 2000

Computational fluid dynamic simulation is performed for the floating turbulent premixed flames stabilized in stagnation flows of Cho et al. [1] and Cheng and Shepherd [2]. They are both in the wrinkled flamelet regime far from the extinction limit with $u'/S^{0}_{L}$ less than unity. The turbulent flux is given in the first moment closure as a sum of the classical gradient flux due to turbulent motions and the countergradient flux due to thermal expansion. The parameter $N_{B}'s$ are greater than unity with the countergradient flux dominant over the gradient flux. The countergradient flux is assumed to be zero in $\bar{c}<0.05$. The flame surface density is modeled as a symmetric parabolic function with respect to $\bar{c}$. The product of the maximum flame surface density and the mean stretch factor is considered as a tuning constant to match the flame location. Good agreement is achieved with the measured $\tilde{w}$ and $\bar{c}$ profiles along the axis in both flames.

• Journal of Pharmaceutical Investigation
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• 제31권4호
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• pp.273-279
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• 2001

The purpose of this study is to characterize the iontophoretic transport of growth hormone releasing peptides (GHRP-6) through hairless mouse skin from aqueous solution. The effect of various factors, such as pH, poloarity, current profile, current density, current duration, ionic strength, drug concentration, and enhancer application was studied to obtain basic knowledge on the transport. We have also studied the stability of GHRP-6 in solution with/without current. The donor chamber was filled with phosphate buffer solution containing GHRP-6 and the receptor chamber was filled with phosphate buffer solution (pH 7.4). Ag/AgCl electrode was used for their stability and reversibility. At a predetermined time interval, sampling was made and the concentration of drug was analysed using HPLC system. The results showed that, compared to passive flux, the total amount of drug transported increased markedly by the application of anodal current. Cathodal flux was similar to passive flux. Flux increased with the current density, the duration of current application and drug concentration. The effect of enhancers on the flux was studied using hydrophilic (5% N-methyl pyrrolidone) and hydrophobic (5% propylene glycol monolaurate, 5% oleic acid) enhancers. Application of enhancer also increased the flux.

• Carbon letters
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• 제2권3_4호
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• pp.192-201
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• 2001

The Carbon/Carbon composite was prepared from 3D carbon fiber preform and coal tar pitch as matrix precursor. In order to evaluate of ablative characteristics of the composite, liquid rocket system was employed Kerosene and liquid oxygen was used as propellants, operating at a nominal chamber pressure of 330 psi and a nominal mixture ratio (O/F) of 2.0. The results of an experimental evaluation were that high density composite exhibited high, while low density composites showed low erosion resistance. The erosion rate against heat flux was highly depended on the density of the materials. The morphology of eroded fiber showed differently according to collision angle with heat flux on the composite. The granular matrix which derived from carbonization pressure of 900 bar was more resistance to heat flux than well-developed flow type matrix.

• 전기학회논문지
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• 제56권3호
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• pp.506-513
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• 2007

This paper proposes a rotary magnetic position sensor which has a sinusoidally magnetized permanent magnet with a small number of poles. To make the sinusoidal magnetic flux density distribution from the permanent magnet, a magnetizing future is optimized by the DOE(Design of Experiments) method. The magnetization process is analyzed using the Preisach model and 2 dimensional finite element method. The magnetic flux density distribution from the magnetized permanent magnet is very similar to ideal sine wave. The simulation result of the magnetic flux density distribution is compared with the experimental one. Also the availability of the proposed rotary type magnetic position sensor is confirmed by position calculation technique.

• 한국분무공학회지
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• 제18권3호
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• pp.140-145
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• 2013

Sub/supercritical spray experiments were conducted, and cryogenic nitrogen and gaseous argon were selected for simulants. liquid nitrogen and gaseous argon were injected in subcritical case, and supercritical nitrogen and near-critical gaseous argon were injected in near-critical/supercritical cases. shadowgraph method was used to visualize spray, and analyzed about the breakup length. The breakup length was measured from numbers of Instantaneous shadowgraph Images from each case, and they were compared with momentum flux ratios and density ratios. It was observed that the relation between breakup length and momentum flux ratio was fitted into former experiment results. and the reasonable constant was suggested about the relation between breakup length and density ratio.