• Journal of Electrochemical Science and Technology
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• v.6 no.4
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• pp.131-138
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• 2015

Electrical discharge machining is an unconventional machining process in which successive sparks applied to machine the electrically conductive materials. Any changes in electrical discharge machining parameters lead to the pieces with distinct surface roughness. The electrical discharge machining process is well applied for high hardness materials or when it is difficult to use traditional techniques to do material removing. Furthermore, this method is widely applied in industries such as aerospace, automobile, molding, and tool making. CK45 is one of the important steels in industrial and electrical discharge machining can be considered as a proper way for its machining because of high hardness of CK45 after thermal operation of the electrical discharge machining process. Optimization of surface roughness as an output parameters as well as electrical discharge machining parameters including current, voltage and frequency for electrical discharge machining of CK45 has been studied using copper tools and kerosene as the dielectric. For such a purpose and to achieve the precise statistical analysis of the experiment results design of experiment was applied while non linear regression method was chosen to assess the response of surface roughness. Then, the results were analyzed by means of ANOVA method and machining parameters with more effects on the desired outputs were determined. Finally, mathematical model obtained for surface roughness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.131-136
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• 2016

Currently, an EDM tapping procedure has comprised some parts of the engraving discharge process for the press die. Usually, tapping has been used in cases where we are unable to mechanically machine using steelwork processes due to an increase in the hardness of a material after heat treatment in relation to a design change or missing process. Here, we analyze the influence of discharge tap shape on discharge time, discharge current, and the number of repetition conditions when a cold-work tool steel (STD11) has been treated with a discharge tapped by a screw-shaped cu electrode. The most important influence on processing condition has been determined to be the number of discharge repetitions. As this number increases, the angle reduction of a thread closes to an angle of the electrode via a power generation reduction. The optimal combination of conditions has been determined to be three discharge repetitions, $180{\mu}s$ of discharge time (same as existing regulations), and 25.4A of peak current. A 0.2749db advantage has emerged after comparing between this combination of optimal conditions and the SN rate of existing regulations.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.313-318
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• 2006

This paper introduces a partial discharge (PD) severity metric, S, based on the evaluation of time-sequence PD data capture and resulting Time-Sequence-Analysis Discharge (TSAD) level distributions. Basically based on an IEC60270 measurement technique, each PD event is time stamped and the discharge level noted. By evaluating the time differences between a previous and subsequent discharge, a 3D plot of time-sequence activity and discharge levels can be produced. From these parameters a measurement of severity, which takes into account dynamic or instantaneous variations in both the time of occurrence and the level of discharge, rather than using standard repetition rate techniques, can be formulated. The idea is to provide a measure of the severity of PD activity for potentially measuring the state of insulation within an item of plant. This severity measure is evaluated for a simple point-plane geometry in $SF_{6}$ as a function of gap distance and applied high voltage. The results show that as the partial discharge activity increases, the severity measure also increases. The importance of future investigations, quantifications and evaluations of the robustness, sensitivity and importance of such a severity measurement, as well as comparing it with typical repetition rate assessment techniques, and other monitoring techniques, are also very briefly discussed.

• Journal of Navigation and Port Research
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• v.32 no.8
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• pp.637-643
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• 2008

When planning outfall system, the first target cif design is to maximize initial dilution of discharge effluent. To achieve the target effectively, the characteristics of mixing phenomenon between ambient and discharged water should be analyzed. Especially the analysis at the Near-Field-Region(NFR) as initial dilution zone should be preceded. Usually, the initial behavior of effluent through outfall system is rising toward the surface due to mixing with ambient water for heat discharge and sinking toward the bottom due to the difference of density for brine discharge. After mixed with eddies accompanied by the ambient water, the plumes are showing the same density and internal current pattern by advection and diffusion. Until recently, lots of studies are being carried out for the optimum design of outfall system. but it is difficult to find any studies of heat and brine discharge at the same time. Therefore, this study is hoped to provide some basic data for optimum design of outfall system.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.674-676
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• 2008

An electrostatic discharge (ESD) or a noise supplied from the outside has an effect on communication between the timing controller (TCON) and the memory element (EEPROM) through the interface between the timing controller and the memory element in liquid crystal displays (LCD). Therefore, we must apply ESD protection methods to LCD operating circuits for a normal operation. Our ESD protection circuit is to prevent from bi-directional communication errors between TCON and EEPROM due to an electrostatic discharge (ESD).

• Journal of Korean Critical Care Nursing
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• v.7 no.1
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• pp.24-32
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• 2014

Purpose: The purpose of this study was to examine the effects of discharge planning on patient satisfaction, the readmission rate and preparedness for discharge in the elderly admitted to the emergency room (ER) for pulmonary disease. Methods: A quasi-experimental intervention study design was used. Older adults with pulmonary health problems in the ER in one general hospital were randomly allocated to either an experimental (n=21, 74.2 years) or control group (n=19, 70.7 years). The experimental group participated in a discharge planning program by a geriatric nurse practitioner. Data were collected from medical records, physical measurements and structured questionnaires including information on demographics, patient satisfaction, readmission, and preparedness for discharge. Results: Participants in the experimental group had significantly better outcomes with regard to patient satisfaction with nursing services (p=.003) and preparedness for discharge (p=.034). However, there was no significant effect on the readmission rate (p=.392) Conclusion: The results suggested that a discharge planning program could bolster nursing service satisfaction and preparedness for discharge in older patients admitted to the ER for pulmonary health problems. To clarify the effects of discharge planning on older patients admitted to the ER, a larger sample population, better instruments for various measures, a new manual on discharge planning and frequent follow-up will be necessary.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2286-2292
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• 2011

In this paper we present the design of Low Noise Amplifier(LNA), mixer and filter for RF front-end part of partial discharge monitoring system. The monitoring system of partial discharge in high voltage power machinery is used to prevent many kinds of industrial accidents, and is usually composed of three parts - sensor, RF front-end and digital microcontroller unit. In our study, LNA, mixer and filter are key components of the RF front-end. The LNA consists of common gate and common source-cascaded structure and uses the resistive feedback for broad band matching. A coupled line structure is utilized to implement the filter, of which size is reduced by the meander structure. The mixer is designed using dual gate structure for high isolation between RF and local oscillator signal.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.243-247
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• 2014

In this paper, we design two types of the sensor module to measure the partial discharge causing failures and electric fires for power incoming/distributer. And evaluate the performance thereof. Analyze the correlation of the phase current and the partial discharge and overheating. Proposes to apply the stability index by utilizing the analyzed information and use in order to prevent the failure or electrical fire of the power incoming/distributer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.626-629
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• 1997

In this study, position optimization of insulation rods and suspension rods in discharge electrode frame of electrostatic precipitator(EP) is performed using finite element analysis(FEA). The object of the optimization is to minimize the difference of altitudes in unevenly sagged horizontal structure and to regulate the size of materials within the allowable stress bounds. Uppermost horizontal channel of discharge electrode frame is highly stressed and uniformity of lowest horizontal angle depends on the position of rods. Ten types of frame are analyzed and one recommended model is presented.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.206-215
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• 1994

A method for simulating general characteristics and temperature characteristics of discharging SCR of the capacitor discharge impulse magnetizer-magnetizing fixture system using SPICE is presented. This method has been developed which can aid the design, understanding and inexpensive, time-saving of magnetizing circuit. As the detailed characteristic of magnetizing circuit can be obtained, the efficient design of the magntizing circuit which produce desired magnet will be possible using our SPICE modeling. Especially, computation of the temperature rise of discharging SCR is very important since it gives some indication of thermal characteristic of discharging circuit. It is implemented on a 486 personal computer, and the modeling results are checked against experimental measures. The experimental results have been achived using 305[V] and 607[V] charging voltage, low-energy capacitor discharge impulse magnetizer-magnetizing fixture of air cleaner DC motor.