• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.83-93
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• 1995

A numerical and experimental investigation on the flow characteristics in the rectangular duct of an MHD propulsion system has been carried out. In numerical analysis, three-dimensional, steady-state, viscous, incompressible electrically conducting fluid flow under the influence of uniformly applied magnetic and electric fields was treated using a finite-difference technique. It was found from the numerical study that when the Lorentz force is weak, the typical parabolic velocity profile under a laminar flow condition changes to an M shaped profile near the electrode region and that the pressure increases linearly from the inlet toward the outlet of the MHD duct under constant electro-magnetic field. In experiment, thrust of the MHD propulsion system can be controlled easily by varying electrode current. The measured pressure gradient along the MHD duct is proportional to the Lorentz force, which is in agreement with the numerical results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2029-2037
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• 2015

The purpose of this study was to investigate the effect the interferential current (IFC) stimulation level according to autonomic nerve system (ANS) of healthy adults. IFC measured with adhesive 2-pole electrodes pad on T1~T4 spinal cord segment level that electrode stimulation of 20 min after. A total of 45 healthy adults participated in the study, who were randomly divided into three groups: 15 of sensory level stimulus group (100 bps, 10~12 mA), 15 of exercise level stimulus group (5 bps, 45~50 mA), 15 of noxious level stimulus group (100 bps, 80~90 mA). Measured items were sympathetic activity and parasympathetic activity. In order to identify the changes in measurement variables before electrode stimulation and after and 30 min stimulation. The comparison of sympathetic and parasympathetic activity in each group revealed that they was changes of after vs 30 min in after electrical stimulation time(p<.05).

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.118.3-118
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• 2001

CLED (Contact Light Emitting Device) has three layers consisting of a transparent electrode, a light emitting layer and a substrate. When the substrate of the CLED comes in contact with a fingerprint under AC input voltage, it makes an electric field between the fingerprint and the device. Due to the electric field, the light is emitted along the ridgeline of the fingerprint. The intensity along the ridge on the surface of the CLED increase in proportion to the electric field. To achieve uniform performance of fingerprint verification devices, inspection system of CLED for quality control were required. In this research, we proposed the factors for quality controls such as dimensions of the CLED, uniformity ...

• Macromolecular Research
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• v.16 no.3
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• pp.200-203
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• 2008

A conducting polymer layer was introduced into the pore surface of mesoporous carbon via vapor infiltration of a monomer and subsequent chemical oxidative polymerization. The polypyrrole, conducting polymer has attracted considerable attention due to the high electrical conductivity and stability under ambient conditions. The mesoporous carbon-polypyrrole nanocomposite exhibited the retained porous structure, such as mesoporous carbon with a three-dimensionally connected pore system after intercalation of the polypyrrole layer. In addition, the controllable addition of pyrrole monomer can provide the mesoporous carbon-polypyrrole nanocomposites with a tunable amount of polypyrrole and texture property. The polypyrrole layer improved the electrode performance in the electrochemical double layer capacitor. This improved electrochemical performance was attributed to the high surface area, open pore system with three-dimensionally interconnected mesopores, and reversible redox behavior of the conducting polypyrrole. Furthermore, the correlation between the amount of polypyrrole and capacitance was investigated to check the effect of the polypyrrole layer on the electrochemical performance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.40-45
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• 2015

Electrode systems: a protrusion on conductor (POC), a protrusion on enclosure (POE), a crack in epoxy plate and a free particle (FP) were fabricated to simulate insulation defects in a gas insulated switchgear (GIS). $SF_6$ gas was filled in the electrode systems by 3 bar and/or 5 bar, respectively. Partial discharge (PD) pulses were detected through a $50{\Omega}$ non-inductive resistor. A calibration test was carried out according to IEC 60270, and the sensitivity was 0.25 pC/mV. PD pulses were distributed in the phase of $50^{\circ}{\sim}135^{\circ}$ and over 95% of them existed in the phase of $55^{\circ}{\sim}120^{\circ}$ for the POC. PD pulses were distributed in the phase of $230^{\circ}{\sim}310^{\circ}$ and over 90% of them existed in phase of $220^{\circ}{\sim}300^{\circ}$ for the POE. PD pulses occurred in the phase of $40^{\circ}{\sim}60^{\circ}$ and $220^{\circ}{\sim}300^{\circ}$ for the crack, and pulse counts were 25% higher in negative polarity than in positive polarity. PD pulses were distributed in every phase unlike to other three electrode systems and the peak magnitude was measured at $118^{\circ}$ and $260^{\circ}$ for the FP. As described above, PD pulses were observed in positive polarity for the POC, in negative one for the POE, in both one for the crack and the FP. In conclusion, it is expected that the identification rate of defect type can be improved by considering the polarity ratio of PD pulses on the PRPDA method.

• Radiation Oncology Journal
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• v.9 no.1
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• pp.27-35
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• 1991

An interstitial radiofrequency needle electrode system was constructed for interstitial heating of brain tissue. Radiofrequency electrodes with Thermotron RF 8 were tested in an agar phantom and in a normal canine brain to determine how variations in physical factors affected temperature distributions. Temperature distributions were checked after heating with 1 mm diameter needle electrode implants on the corners of 1 and 2 cm squares in a phantom and plot isotherms for various electrodes arrangement. We observed that the 1 cm square array would heat a volume with a 1.25 cm radius circular field cross section to therapeutic temperatures ($90\%$ relative SAR using Tm) and the 2 cm square array with a 1.75 cm radius rectangular field with central inhomogeneity. With 2 cm long electrode implants, we observed that the 1 cm square array would heat a 3 cm long sagittal section to therapeutic temperature ($90\%$ relative SAR using Tm). We found that radiofrequency electrodes could be selected to match the length of the heating area without affecting its performance. The histopathological changes associated with RF heating of normal canine brains have been correlated with thermal distributions. RF needle electrode heating was applied for 50min to generate tissue temperatures of $43^{\circ}C$. We obtained a quarter of the heated tissue material immediately after heating and sacrificed at intervals from $7\sim30$days. The acute stage (immediately after heating) was demonstrated by liquefactive necrosis, pyknosis of neuronal element in the gray matter and by some polymer-phonuclear leukocytes infiltration. The appearance of lipid-laden macrophages surrounding the area of liquefaction necrosis was demonstrated in all three sacrificed dogs. Mild gliosis occurring around the necrosis was demonstrated in the last sacrificed (Days 30) canine brain.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.154-157
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• 2000

Distributed piezoelectric sensor and actuator system has been designed for the active vibration control of shell structure. PVDF is used for the materials of sensor/actuator. To prevent the adverse effect of spillover, distributed modal sensor/actuator system is established. Although shell structure is three-dimensional structure, the PVDF sensor/actuator system can be treated as two-dimensional Finite element programs are developed to consider curved structures having PVDF modal sensor/actuator. The nine-node Mindlin shell element with five nodal degree of freedoms is used for finite element discretization. The electrode patterns and lamination angle of PVDF sensor/actuator are optimized to design the modal sensor/actuator system Genetic algorithm is used for optimization. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator for the first and second modes of singly curved cantilevered shell structure are designed using mentioned methods. Discrete LQG method is used as a control law. Experimental demonstrations of the active vibration control with designed sensor/actuator system have been performed successfully.

• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.91-97
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• 2012

In this study, cost analysis of electrokinetic (EK) restoration process for desalination of saline agricultural land was performed for field application based on a pilot scale field application. For reasonable cost analysis, EK process was classified into three major parts: system design, installation and operation. Cost of system installation consists of materials and installation for electrode/electric wire, power supply and data monitoring, drainage system, etc. Operation cost was calculated based on electrical consumption and water charges for EK process. Total cost for EK process was 2,943,013 won for $1000m^2$ in greenhouse area. Cost for system installation was 2,553,786 won, that is, 87% of total cost, while cost for system operation was 389,229 won, that is, 13% of total cost.

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.75-84
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• 2023

The accumulation of spent carbide (YG8), not only pollutes the environment but also causes waste of tungsten, cobalt and other rare metal resources. To better address this issue, we proposed a combined electrochemical separation process of low-temperature aqueous solution and high-temperature molten salt for tungsten and cobalt. H₂WO₄ was obtained from spent carbide in an aqueous solution, and we calcined it to obtain WO₃, which was used as a raw material to obtain tungsten by using molten salt electrodeposition. The influence of the current efficiency and the electrochemical behavior of the discharge precipitation of W(VI) were also studied. The calcination results showed that the morphology of WO₃ was regular and there were no other impurities. The maximum current efficiency of 82.91% was achieved in a series of electrodeposition experiments. According to XRD and SEM analysis, the recovered product was high purity tungsten, which belongs to the simple cubic crystal system. In the W(VI) reduction mechanism experiments, the electrochemical process of W(VI) in NaCl-Na₂WO₄-WO₃ molten salt was investigated using linear scanning voltammetry (LSV) and chronoamperometry in a three-electrode system. The LSV showed that W(VI) was reduced at the cathode in two steps and the electrode reaction was controlled by diffusion. The fitting results of chronoamperometry showed that the nucleation mechanism of W(VI) was an instantaneous nucleation mode, and the diffusion coefficient was 7.379×10^-10 cm²·s^-1.

• Korean Journal of Acupuncture
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• v.24 no.4
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• pp.55-67
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• 2007

Objectives : The repeatability and reproducibility of MIR-2, a newly developed impedance measurement device (four electrode method) on skin are of the meridian system, is evaluated and a method to improve the reliability is discussed. Methods : Multiple gage R&R studies were conducted for the impedance measurements over bilateral KI3 acupoint in ten participants by three assessors using MIR-2 device. Gage R&R studies were repeated after controlling the acupoint locating method or one value correction by replacing one assessor's outlying value with an average of the other assessors' values to explore any feasibility of improvement of measurement reliability. Results : Controlling acupoint locating method and replacing one value with an average of other assessors' value led to improved variation metrics in a gage R&R study. Conclusions : Measurement reliability can be improved by controlling measurement procedures or by using repeated measurement method, which will facilitate development of clinically applicable measurement device with reliability.