• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1520-1522
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• 1994

The clarification of insulation capability of GIS(Gas Insulated Substation) under very fast transient overvoltages such as disconnector/circuit-breaker induced surge is very important for establishing not only a rational insulation testing method, but also insulation design intending to make GIS more reliable and more minimized. One of the absolute prerequisits for this is that more accurate measurement of VFTO. This describes capacitive voltage measuring methods for high voltage steep-footed oscillating waves using capacitive coupling principle and their systems including source and load impedances. Time domain response of unit step and its frequency characteristics are also investigated.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.298-303
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• 2011

A capsular endoscope (CE) for inspection of the large intestine requires a motor for backward navigation against the autonomous travel in the intestine. This study proposes an HF power system for generating a magnetic field and for delivering wireless power to the internal or implanted medical devices. The magnetic field is generated by a wound coil (L) around a wooden frame, and the current is driven to the coil through a resonating capacitor (C). The characteristics of the resonance frequency shifting of the L-C series circuit are analyzed. A stable magnetic field intensity in the field coil is maintained by a specially designed frequency tracking system that automatically follows the L-C resonance frequency. Testing confirmed that the oscillation system tracks well the parameter changes of the electric components caused by the operating conditions or environmental variations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.121-128
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• 1998

A new magnetic ballast was designed and developed to get high luminous efficiency. The core material of new magnetic ballast was G-9 and its shape of core is modified. The diameter of the coil was upgraded to 0.5[mm], and a new power-saving circuit was designed for the semiconductor ignition starter. The experimental results of the ballast showed reduction of the electric loss in the magnetic ballast about 1.7Watt (0.5[%]). The luminous efficiency was increased by 6.2 lm/Watt (7.6[%]) and the ballast efficiency factor(BEF) of 1.09(7.6[%]). The prototype was tested through national standard testing procedure. A high efficient energy-using equipment (the second grade in the efficiency of energy consumption) was certified. The saving power of 1.7[W] was shown by lighting appratus for fluorescent lamps. The result will be used for the high efficient magnetic ballast technology.nology.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.7
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• pp.515-520
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• 2018

A large number of lithium-ion batteries are arranged in series and parallel in battery packs, such as those in electric vehicles or energy storage systems. As battery packs age, their output power and energy density drop because of voltage deviation, constant and non-uniform exposure to abnormal environments, and increased contact resistance between batteries; this reduces application system efficiency. Despite the balancing circuit and logic of the battery management system, the output of the battery pack is concentrated in the most severely aged unit cell and the output is frequently limited by power derating. In this study, we implemented a cell imbalance detection algorithm and selected parameters to detect a sudden decrease in battery pack output. In addition, we propose a method to increase efficiency by applying the measured testing values considering the operating conditions and abnormal conditions of the battery pack.

• Journal of Applied Reliability
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• v.11 no.3
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• pp.251-265
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• 2011

Low-noise amplifier(LNA) is a component that amplifies the signal while lowering the noise figure of high-frequency signal. LNA holds a very important position in RF system so that it is widely used for telecommunication. Electro static discharge(ESD) is the most common cause of malfunction for low-powered components, such as Large Scale Integration and IC type LNA is weak in ESD. This thesis studies static effect of communication LNA. It analyzes ESD effect, which occurs within LNA circuit, and describes testing standard and methods. In order to find out LNA's susceptiblity to electro static, two well-recognized communication IC type LNA models were selected to be tested. Then static-induced malfunction was carefully analyzed and it suggests architectural problem and improvement from the LNA's ESD point of view.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.1
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• pp.61-71
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• 2003

Interconnect test for highly integrated environments like SoC, becomes more important as the complexity of a circuit increases. This importance is from two facts, test time and complete diagnosis. Since the interconnect test between IPs is based on the scan technology such as IEEE1149.1 and IEEE P1500, it takes long test time to apply test vectors serially through a long scan chain. Complete diagnosis is another important issue because a defect on interconnects are shown as a defect on a chip. But generally, interconnect test algorithms that need the short test time can not do complete diagnosis and algorithms that perform complete diagnosis need long test time. A new interconnect test algorithm is developed. The new algorithm can provide a complete diagnosis for all faults with shorter test length compared to the previous algorithms.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.615-622
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• 2015

Recently Digital-TachoGraph(DTG) was mounted mandatorily in commercial vehicles(Taxi, Bus, etc.). DTG records accurate and detailed information of the running state of vehicles related to traffic accident, such as Time, Distance, Velocity, RPM, Brake ON/OFF, GPS, Azimuth, Acceleration. Thus those standardized data can play an important role in traffic accident investigation and reconstruction. To develope the accurate and objective method using the DTG data for the reconstruction of traffic accident, we had conducted several tests such as driving test, high speed circuit test, braking test, slalom test at Korea Automobile Testing & Research Institute(KATRI), and collision test at Korea Automobile insurance repair Research and Training center(KART) with the vehicle equipped with several DTG. Development of the program which enables the reading and analysis of the DTG data was followed. In the experiments, we have found velocity error, RPM error, brake signal error and azimuth error in several products, and also non-continuous event data. The cause of these errors was deduced to be related to the correction factor, the durability of electronic parts and the algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.6
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• pp.1045-1054
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• 2006

In this paper, described a design result of bus interface modulo for multiple level MU-SID-1553 data bus network. In general, MIL-SID-1553 network is used for single level data bus topology. But, according to applied system's structure. multiple level bus architecture is required., And for his, micro processor must be involved for system be, and a additional hardware and software functions are needed. The designed data bus interface module is simply consists of communication transceivers and simple electronic circuit without micro processor. Through the hardware testing and software simulation, the functional performance of the designed interface module was successfully validated.

• Journal of Power Electronics
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• v.8 no.2
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• pp.181-191
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• 2008

The task performed by induction motors grows increasingly complex in modern industry and hence improvements are sought in the field of fault diagnosis. It is essential to diagnose faults at their very inception, as unscheduled machine down time can upset critical dead lines and cause heavy financial losses. Artificial intelligence (AI) techniques have proved their ability in detection of incipient faults in electrical machines. This paper presents an application of AI techniques for the detection of inter-turn insulation and bearing wear faults in single-phase induction motors. The single-phase induction motor is considered a proto type model to create inter-turn insulation and bearing wear faults. The experimental data for motor intake current, rotor speed, stator winding temperature, bearing temperature and noise of the motor under running condition was generated in the laboratory. The different types of fault detectors were developed based upon three different AI techniques. The input parameters for these detectors were varied from two to five sequentially. The comparisons were made and the best fault detector was determined.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.261-263
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• 1994

This paper deals with the on off arc characteristics of electromagnetic relay contacts contaminated by NaCl and $H_2SO_4$. In this paper, I have studied the characteristics of on-off voltage waveform. the contact errosion, contact surface analysis by SEM and EDAX under changed R-L parameter of testing circuit. After considers these result, I have tried to promote the diagnosis method and developed the contacts. As a results, (1) The arc duration and the numbers of arc occurrence characteristics are depended on contamination degree. The contamination degree is high when the arc characteristics is high. (2) Under clean condition, arc occurrence voltage, surge peak voltage, arc duration and the rate of contact errosion is lower than wet condition. (3) Surge peak voltage and arc duration is depended on L parameter. When L is High, the arc characteristics is high.