• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.85-95
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• 1995

Radiation measuring system using wireless communication method with single channel has been diveloped and tested. In this system, radiation signals from GM tube are transformed into digital pulses in pulse processing circuit and modulated in FSK (frequency shift keying) circuit for digital communication and then wirelessly transmitted to a receiving unit. The digital pulses received are then demodulated in FSK circuit and converted into radiation dose/dose rate in the data acquisition unit to display on the screen of a personal computer. The performance of this system was evaluated by using both a pulse generator and a standard radiation source(Cs-137). In both cases, digital pulses with 5V were observed in pulse processing circuit without distortion of their shape through wireless communication system. The experimental results of radiation measurement by this system after several test-irradiation of GM detector to a standard radiation source(Cs-137), showed good agreement with irradiation dose rate within 10% difference, and proved that this system could be effectively utillized as radiation measuring instrument. It is expected that this wireless radiation measuring system developed for the first time in Korea, can be used as a radiation monitor as well as a personal dosimeter if we can further improve this system to adopt wireless multichannel communication system.

• Journal of IKEEE
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• v.21 no.1
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• pp.7-12
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• 2017

This paper proposed the ESD protection circuit for the high-voltage applications with latch-up immunity and high area efficiency. The proposed circuit has high holding voltage compared to the conventional SCR by inserting the floating regions and applying the segmentation layout. It has the area efficiency is more higher due to the segmentation layout. The proposed circuit has the higher holding voltage of the 21.67V than the 3.39V of the conventional SCR. The electrical characteristics of the proposed circuit was investigated by TCAD simulator, and was proved through the fabrication by using the 0.18 BCD process.

• Fire Protection Technology
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• s.28
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• pp.48-54
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• 2000

The technique detects radiant energy form a flaming fire of fuels contained carbonaceous material can be applied to fast growing fires. This technique applied detectors are ultimately effective when early detecting fire alarm system is required or the smoke and heat detectors can not applied. In Korea Fire regulation, a flame detector should be install in case that the installation height is higher than 20[m], chemical plant, hangar refinery. Therefore it is really necessary that a flame detector has to be developed as soon as possible. With foundation technique of flame detector, ideal sensing element and stable circuit design, a trial UV flame detector is manufactured. The stable and reliable technique of flame detector is established through the repeateed perfomance test and modification. An early detecting fire alarm device is developed through the modification, supplement of the structure and circuit. Results of the R & D for the manufacture of an excellent flame detecting device is carried out with the establishment of technique for the mass production and the qualified manufacturing process.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.455-459
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• 2004

Electrostatic discharge(ESD) is a serious reliability concern. It causes approximately most of all field failures of integrated circuits. Inevitably, future IC technologies will shrink the dimensions of interconnects, gate oxides, and junction depths, causing ICs to be increasingly susceptible to ESD-induced damage [1][2][3]. This thesis shows the optimization of the ESD protection circuit based on the tested results of MM (Machine Model) and HBM (Human Body Model), regardless of existing Reference in fully silicided 0.18 um CMOS process. His thesis found that, by the formation of silicide in a source and drain contact, the dimensions around the contact had a less influence on the ESD robustness and the channel width had a large influence on the ESD robustness [8].

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.140-142
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• 2005

This paper describes the current- based compact digital motor protective relay for low and high voltage induction motors, which are widely used in industrial and commercial power systems. The existing protective relays for motor protection had only overload, short circuit, reverse phase, open circuit and grounding protective elements, and measurement, start/stop control function. But in present day, for automation system, various functions are required, especially motor management and sequence control function and more. To meet these requirements, we developed an economic current-based compact digital motor protective relay which had various function to control, manage and monitor the induction motor.

• Journal of the Korea Safety Management & Science
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• v.11 no.2
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• pp.87-94
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• 2009

In the fire there are fusion signs and damage by fire, and insulation aging and carbonization of the electric wiring in the ignition spot because of special characteristic of the appliance in the electricity fire. Because of the physical factor applied in the damage of fire, the decision of ignition spot by eye investigation is insufficient. In this paper, the cause of electricity fire is researched. The focus is on the operation state of operated MCCB(Molded Case Circuit Breaker) at the time of electricity fire. Through grasping the operation principle of MCCB and the experiment, the state of MCCB after fire suppression is discriminated. The distinction possibility on the exist of electricity fire is proposed.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1885-1891
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• 2010

Recently metropolitan local governments is actively introducing urban railway's expand and light rail transit as a means of new transport system. DC electricity feeder system operating in the domestic urban railway is typically a feedback circuit consisted of the contact wire and electric railway vehicle via rail. But stray current is to be defined as a current flowing on a structure that is not part of the intended electrical circuit with respect to a given structure. Stray current is generally results from the leakage of return currents from large DC traction systems that are grounded or have a bad earth-insulated return path. At the place where the current leaves the rail and metallic structures, electrolytic corrosion may take place. This paper presents comparison analysis of field test methods based on criteria of electrolytic corrosion protection of buried metallic structures adjacent to DC traction systems.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.234-236
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• 2002

The Co-Gen System which maximize energy efficiency was installed at the industrial plants at the initial stage. However Small Scale Co-Gen System was expanded even to the general end-users such as housing and building owing to ESCO business recently. For this SSC, inter-connected operation to the utility is desirable due to voltage and frequency fluctuation following to unbalance between power output and load. Then voltage unbalance with utility system, frequency, increase of short circuit capacity, reclosing, and ALTS etc. should be fully considered for the inter-connected operation. Voltage variation, protection coordination, Co-Generators single running, and short circuit capacity should also be solved. To research the method and solve the problems through the field test and application, we study individual customers Co-Gen System as a case study.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2089-2091
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• 2000

Pulsed power systems consist of a capacitor bank, an isolated high-voltage charging power-supply, high-current bus-work for charging and discharging and a control system. In such pulsed power systems, the operating-lifetime of the capacitors is closely dependent on the voltage reversal. Hence, most capacitor-discharging systems includes crowbar circuits. The crowbar circuit prevents the capacitor recharging with reverse voltage. Usually it consists of crowbar resistors and high pulse-current diode-stacks connected in series. The requirements for the diode-stacks are fast-recovery time and high-voltage and large-current ratings, which results in the high cost of the pulsed-power system. This paper presents a protection scheme of a charging and discharging system of a 500kJ capacitor bank using a low-cost crowbar circuit and safety-fuses.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.23-24
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• 2007

Most of modern wind turbines employs a doubly-fed induction generator (DFIG) system because it has many advantages due to variable-speed operation, relatively high efficiency and it small converter size. The DFIG system uses a wound rotor induction machine so that the magnetizing current of the generator can be fed from both the stator and the rotor. This paper presents a protection relaying algorism for DFIG using the DQ equivalent circuits. The induced voltages calculated from the stator and rotor sides are nearly the same in the steady state. They become different in the DQ equivalent circuits during an internal fault. The proposed algorithm compares the inducted voltages estimated from the stator and the rotor circuit converted into the stationary reference frame. If the difference between the induced voltages exceeds the threshold, the proposed algorithm detects an turn-to-turn fault.