• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.783-789
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• 2018

This paper investigates the relationship of voltage and current waveform between normal piezo injector and deterioration abnormal piezo injector. The experimental methods using Pico oscilloscope and GDS scan tool are employed to measure current and voltage waveform and fuel pressure of piezo injector. The experiment is carried out during no-load condition. A summary of the important results are as follows. 1) In case of normal injector, the fluctuation of duration time of piezo injector was linearly and regularly decreased with increasing engine speed, but the that of deterioration piezo injector was irregularly decreased with increasing engine speed. 2) In main injection, the peak value of the current waveform of abnormal injector was larger than that of normal injector, the duration time of deteriorated abnormal injector was less than that of normal injector at 800rpm and 1500rpm, but the duration time of deteriorated abnormal injector was larger than that of normal injector at 2000rpm and 3000rpm. This irregularity appears to be caused by the deterioration of the injector.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.5
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• pp.195-200
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• 2009

CRT-based RSA algorithm, which was implemented on smartcard, microcontroller and so on, leakages secret primes p and q by fault attacks using laser injection, EM radiation, ion beam injection, voltage glitch injection and so on. Among the many fault injection methods, voltage glitch can be injected to target device without any modification, so more practical. In this paper, we made an experiment on the fault injection attack using abnormal source voltage. As a result, CRT-RSA's secret prime p and q are disclosed by fault attack with voltage glitch injection which was introduced by several previous papers, and also succeed the fault attack with source voltage blocking for proper period.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.101-105
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• 2021

Encouragement of DER from Korean government with several policies boosts DER installation in power system. When the penetration of DER in the grid is getting high, loss of generation with break-away of DER by abnormal grid conditions should be considered, because loss of high generation causes abnormal low frequency and additional operations of protection system. Therefore, KEPCO where is Korean power utility is preparing improvement in regulations for DERs connected to the grid to support abnormal grid conditions such as low and high frequencies or voltages. This is called 'Ride Through' because the requirement is for DER to maintain grid connection during required periods when abnormal grid conditions occur. However, it is not easy to have a test for ride through capability in reality because emulation of abnormal grid conditions is not possible in real power system in operation. Also, it is not easy to have a study on grid effect when ride through capability fails with the same reason. PHILs (Power Hardware In the Loop System) makes it possible to analyze power system and hardware performance at once. Therefore, this paper introduces PHILs test methods and presents verification of ride through capability especially for low voltage grid conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1991.10a
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• pp.83-89
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• 1991

The partial discharge properties of interface layer in Mica-Epoxy composite, which has been mainly used for the coil insulating material of high voltage machinery, are different from those of resins due to the abnormal interface layer to be presented between inorganic material and resin. Accordingly, the study on discharge of interface in composite insulting system is strongly requsted for not only an increasing of insulating strength, but also the basical information of diagnosis system for high voltage equipment. As a result, it has been confirmed that the interface is an abnormal resin layer and the contact states at interface is depended upon the density of silane aqueous solution. Pulse frequency at abnormal interface shows a linear increasing with enlargement of discharge quantity. Whereas, in case of normal interface, pulse frequency property represents exponential increasing at the point of saturating. A life model can be diagramed from results of time dependance of skewness, and a survival life time can be quantified from the life model suggested.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.36-37
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• 2013

This paper presents high voltage operation sensing boost converter with high side current. Proposed topology has three functions which are high voltage driving, high side current sensing and low voltage boost controller. High voltage gate driving block provides LED dimming function and switch function such as a load switch of LED driver. To protect abnormal fault and burn out of LED bar, it is applied high side current sensing method with high voltage driver. This proposed configuration of boost converter shows the effectiveness capability to LED driver through measurement results.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.27-37
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• 1997

Internal combustion engine is the main source of environmental pollutants and therefore better technology is required to reduce harmful elements from the exhaust gases all over the world. Especially, harmful elements from the exhaust gases are caused by incomplete combustion of mixture inside the engine cylinder and this abnormal combustion like misfire or partial burning is the direct cause of the air pollution and engine performance degradation. the object of this research is to detect abnormal combustion like misfire and to keep the engine performance in the optimal operating state. Development of a new system therefore could be applied to a real car. To realize this, the spark-plug in a conventional ignition system is used as a misfire detection sensor and breakdown voltage is analyzed. In this research, bias voltage(about 3kV) was applied to the electrodes of spark-plug and breakdown voltage signal is obtained. This breakdown voltage signal is analyzed and found that a combustion phenomena in engine cylinder has close relationship with harmonic coefficient K which was introduced in this research. Newly developed combustion diagnostic method( breakdown voltage signal analysis) from this research can be used for the combustion diagnostic and combustion control system in an real car.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.3
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• pp.199-206
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• 2010

Matrix converter is an energy conversion device of controlled power semiconductor switches that directly connects the three-phase source to the three-phase load. With no dc-link components for energy storage in the matrix converter the input current depends directly upon the load currents and the switch state of the converter. Therefore the unbalanced and distorted input voltages can result in unwanted output harmonic currents. This paper presents a current compensator based on neural network to improving output current quality for matrix converter under abnormal input voltage conditions. The effectiveness and feasibility of the proposed technique has been proven through numerical simulations and experimental tests.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.674-679
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• 2011

In this paper, we experimented and analyzed about electric fire risk assessment methods of LED lightings for outdoor. LED lighting is composed of AC power lines, AC/DC converter, DC power lines and LED lamps. There are some risk factors of electric fire in LED lighting such as short circuit between power lines or power line and ground, dielectric breakdown, leakage current, abnormal voltage inflow, poor contacts(connections), etc. As a result of this study, insulation coverings of wire was ignited due to dielectric breakdown between power lines and molten marks were formed in copper conductor. LED lighting was blown out while short circuit, beside that, electrical disorder did not occur. When abnormal voltage was inflowed, electronic components such as varistor, condenser were damaged. Partial heating was produced and insulation was melted and carbonized by arc and heating while poor contacts were happened. We expect that the results of this study would be helpful for electrical safety of LED lightings for outdoor.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.164-167
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• 2001

In resent years, electric power quality has become an important issue in power system. Voltage variation and compensation countermeasures of KEPCO system in west Gyeongnam have been simulated using PSS/E. In this paper, in the abnormal power system, the adaption of SVC, high speed and continuous control are simulated for voltage compensation. It is shown that the SVC is the optimal voltage compensation method in loop power system or 2 lines radial system.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.83-90
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• 2004

Generally, electronic appliances are used on the basis of normal power source supply. The power source inevitably includes the abnormal condition, such as, sudden voltage sagging, power interrupt, and induced noises. As the electronic appliances which include micro-controller-based circuits are being increased recently, the controller circuit sometimes malfunctions by the abnormal condition of the power source. This situation causes serious problems such as hitch of electric appliance, fire and medical instrument glitch, which produces serious situations. In this paper, development of power interrupt tester which is highly suitable for an endurance test device under abnormal power source to microprocessor-based circuits is proposed 89C2051 microcontroller is performed to make power interrupt signal, and software controls peripheral hardwares and built-in functions. Experimental results of this study will offer a good application to electronic appliance maker as a test device of hardware and software debugging use.