• 한국표면공학회지
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• 제49권5호
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• pp.431-438
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• 2016

This research investigated the relationship between the corrosion damage characteristics of offshore wind steel substructure and the time of current density application by electrochemical accelerated short-term corrosion test. The galvanostatic corrosion was conducted on the steel specimens in natural seawater with a constant current density ranging from $1mA/cm^2$ to $200mA/cm^2$ for 1 ~ 180 min. Macro and micro observation was carried out on the surface of the corrosion damaged area using SEM and 3-dimensional analysis microscope. The weight loss of the specimens before and after was calculated as the difference between the initial weight prior to corrosion and weight after removal of the corrosion product. It was shown that during galvanostaic corrosion process, the corrosion behavior could be characterized by the onset of pitting corrosion in the early stage and the uniform corrosion in the late stage, showing damage development in the depth direction with the time of current application. The result of the 3D analysis revealed that both damage depth and surface roughness increased with increasing time of current application. The weight loss curves with time showed that a coefficient of determination ($R^2$) was relatively high for the relationship between the time of current application and weight loss. As a result, the degree of corrosion can be controlled by simply varying the time of current application.

• 한국표면공학회지
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• 제55권5호
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• pp.292-298
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• 2022

In this study, PEO (plasma electrolytic oxidation) film formation behavior of AZ31 Mg alloy under application of 300 Hz pulse current was studied by the analyses of V-t curve, arc generation behavior, PEO film thickness and morphology of PEO films with treatment time in 0.05 M NaOH + 0.05 M Na₂SiO₃ + 0.1 M NaF solution. PEO films was observed to grow after 10 s of application of pulse current together with generation of micro-arcs. PEO film grew linearly with treatment time at a growth rate of about 5.58 ㎛/min at 200 mA/cm² of pulse current but increasing rate of film formation voltage became lowered largely with increasing treatment time after passing about 250 V, suggesting that resistivity of PEO films during micro-arc generation decreases with increasing film formation voltage at more than 250 V.

• 한국표면공학회지
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• 제49권4호
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• pp.363-367
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• 2016

For the industrial application of electropolishing process, we investigated electropolishing characteristics of stainless steel through increasing the specimen size or electrode gap. In this study, we performed a set of experiment with the specimen size of $10cm{\times}10cm$ and the electrode gap of 1 cm or more. In the view of the electropolishing process, the electrolyte temperature and the polishing time were most important factors compared with the current density and the electrode gap. Especially, the electrolyte temperature most importantly affected surface roughness and current efficiency on electropolishing characteristics. For the industrial application of electropolishing process, it should be considered for important factors such as electrolyte temperature, polishing time, current density and electrode gap, etc.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.215-216
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• 2015

The application of fault current limiter(FCL) reduces power system fault current for circuit breaker to operate properly due to reduced fault current. Also FCL reduces through fault current to the power system equipments. But FCL has changed power system parameters for short time, before application the magnitude of register, triggering current and protective relay coordination have to be studied. In this paper we will examine protective relay coordination with FCL. And propose better solution to assist improving of power system operation through the application of FCL.

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.46-50
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• 1999

The application of pulsed electric field was investigated in the crossflow ultrafiltration of BSA (bovine serum albumn) to economize the application time of electric current as well as to avoid inherent problems of long-term application of electric field. During the application of various cyclic patterns of pulsed electric current, the averaged filtration flowrate and the degree of concentration were maintained higher than those obtained in the absence of electric current application. The temperature increase, pH change, and BSA loss by electrodeposition were all negligible during the operation. The averaged filtration flowrate increased as the ON/OFF duration ratio of electric current was higher and as the period of ON/OFF cycle was shorter. The re-establishment of concentration polarization was dependent to the duration of current OFF state and, therefore, a longer duration of OFF state was not favorable in maintaining higher filtration flow rate. Although the averaged filtration flowrate was enhanced as the magnitude of electric current increased, the flowrate enhancement became smaller as the magnitude of current value above which the degree of electrokinetic depolarization is no further improved.

• 한국안전학회지
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• 제30권4호
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• pp.14-19
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• 2015

The purpose of this paper is to study the correlation application that electrical fire causes occurs for overcurrent and leakage current signals in the indoor wiring. In the order to purpose, the causes data of overcurrent, or leakage current of electrical fire are drawn out referring to past studies, consulting with experts and experimental data. The correlation application was then applied with fuzzy logic of intelligent technique. To check the reliability and performance of the correlation application, modified center of area(CoA) was adopted to calculate the possibility that electrical fire occurs, whose value was then compared to the results. The chance of electrical fire calculated is higher when two causes of fire are put into the CoA of the correlation application of this paper than that of when each cause is separately put into the CoA. The correlation application developed in this study enables better analysis on possible electrical fire due to overcurrent, or leakage current and provides managers with the possibility of electrical fire so that they can better manage at a time of overcurrent, or leakage current.

• 한국표면공학회지
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• 제52권2호
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• pp.72-77
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• 2019

To study the characteristics of AC driven OLED, we fabricated the fluorescent OLEDs and analyzed the electroluminescence characteristics of OLEDs with AC negative voltage. The luminance and the current density of the OLED decreased, and the number and size of the dark spots increased in proportion to the duration time and level of the applied AC negative voltage. The current efficiency of the OLED was improved when high AC negative voltage was applied within a short time. When the AC negative voltage of 10 V was applied for 1 minute, the efficiency was improved by 12.4%. Also, the degradation of luminance and current efficiency due to the duration of light emission was improved in the case of OLED applied for 1 minute with 10 V AC negative voltage. These are expected as a result of the improvement of the leakage current characteristics by eliminating the short-circuit region formed by the defect of the OLED at the AC negative high voltage. As a result, the continuous application of AC negative voltage reduced the luminance and the current density of OLED, but the temporary application of AC negative voltage with the proper time and voltage could improve the efficiency and lifetime of OLED.

• 한국환경과학회지
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• 제18권11호
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• pp.1225-1234
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• 2009

The aim of this research was to apply experimental design methodology in the optimization condition of electrochemical oxidation of Rhodamine B(RhB). The reactions of electrochemical oxidation were mathematically described as a function of parameters amounts of current, NaCl dosage, pH and time being modeled by the use of the central composite design, which was used for fitting quadratic response surface model. The application of response surface methodology using central composite design(CCD) technique yielded the following regression equation, which is an empirical relationship between the removal efficiency of RhB and test variable in actual variables: RhB removal (%) = 3.977 + 23.279$\cdot$Current + 49.124$\cdot$NaCI - 5.539$\cdot$pH - 8.863$\cdot$time - 22.710$\cdot$Current$\cdot$NaCl + 5.409$\cdot$Current$\cdot$time + 2.390$\cdot$NaCl$\cdot$time + 1.061$\cdot$pH$\cdot$time - $0.570{\cdot}time^2$. The model predicted also agree with the experimentally observed result($R^2$ = 91.9%).

• 전기의세계
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• 제26권6호
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• pp.59-65
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• 1977

A study on the decreasing method of secondary arc current on single phase reclosing. One of the major problem in case of using the single phase reclosing scheme for long distance UHV transmission line is the time required to deionize secondary arc current. This paper descritbes the way of inducing the formular of secondary arc current originated at the times of opening and closing the ground interrupting switch. The result was investigated by the method of numerical analysis and proved that the secondary arc current was decreasing sufficiently. Application of this method proposed by the authod makes it possible to deduce the dead time and to improve success-rate of reclosing.

• 대한인간공학회지
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• 제31권1호
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• pp.93-100
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• 2012

Objective: This study is to review the current state of services offered to pharmacy users, and develop a service design converging a prescription service and a smart phone application service in order to enhance patients' experience at pharmacies and home. Background: Under the new medical system; separation of prescribing and dispensing drugs, a doctor writes a prescription to their patients and patients have their prescription filled at the pharmacy. As the number of flue, allergy and atopy patients has increased, waiting lines have been longer at pharmacies. Besides, the current medical service system lacks of providing proper information on prescribed pills to patients. There are already services offered during waiting times such as offering free drinks, magazines or suggesting general drugs which you can buy without prescription, however they neither cover the current medical service's shorts nor shorten the waiting time. Method: I researched objective and perceived waiting times reduction methods, the current service status at pharmacies, and the government's policy direction in a medical service. Also, I observed a patient's journey from the hospital to pharmacy and then home. I examined the circumstance at pharmacies, patients' behaviors and their thoughts during their journey, and extracted three main goals to design a service in order to help patients have positive perception during the waiting time; (1) to reduce the perceived time by the way of visualizing time and offering readings about what patients consider necessary, (2) to educate patients what they are into and how to get through, (3) to establish trust among patients, doctors and pharmacists. Based on three goals, I designed a structure and a wireframe for a new service application of smart phones. Results: With a new service design for pharmacy users, users can track their medical record and visit the information about their current medical treatments anytime. Also the service helps patients build reliable relationships with doctors and pharmacists. Conclusion: Experience is not just an activity but series of multiple activities. The serving range of a medical service should not be determined by stakeholders but user's holistic experience. By approaching a service design with a holistic vision, it can enrich not only a temporary experience but also a whole life well being. Application: Since there are already many service applications advising patients about their illness and finding right doctors, this service design is focused on the experience from getting a prescription till feeling better. The next move is to combine those two parts medical services and design an integrated service application. As a prescription is going to be coded in numbers, we might consider to design an un-attended pharmacy which can shorten huge amount of time for filling prescriptions.