• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.2
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• pp.85-92
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• 2003

This paper presents an electric power generating system for stand-alone health monitoring sensor unit of bridge structure based on ambient vibration of bridge. In this paper, a novel electric power generator which has minimum effect of armature reaction is proposed. The related mechanical and electrical design equations are obtained, and a pilot generator has been implemented. In addition, the charging system for extremely low generator current is discussed, and some improvements are identified for the system. This investigation reveals that diode characteristics of rectifier is dominant factor in the charging process. Finally, both the simulation, which uses real measurement data of the Namhae bridge as input of the pilot generator, and indoor test are carried out. The results showed the applicability and effectiveness of the stand-alone vibration powered generator.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.747-752
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• 2020

The maintenance of sensor networks, especially sensor networks installed in a wide area for regional monitoring has been an issue for a long time. In this study, a system that supplies energy to the sensor network using a robot is proposed, and the survival conditions of the sensor network are identified using the energy consumption rate of the sensor network, the energy transfer rate, and the moving distance of the robot as variables. Through numerical verification and robot charging simulation, the proposed system survival conditions are shown to be valid, and the feasibility of the maintenance method of the sensor network using the robot is validated through actual charging experiments.

• Journal of the Korean Institute of Gas
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• v.25 no.4
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• pp.57-62
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• 2021

In this study, risk assessment was conducted in case of leakage of storage facilities (tube trailer) using the HyKoRAM program developed through international joint research. The high-pressure gas facilities in the hydrogen filling station are divided into four main categories: storage facilities (tube trailers), processing facilities (compressors), compressed gas facilities, and filling facilities (dispensers). Among them, the design specifications of the tube trailer, which is a storage facility, and the surrounding environmental conditions were reflected to construct an accident scenario with previously occurring accidents and potential accidents. Through this, we identify the risks of storage facilities at hydrogen refueling stations and suggest measures to improve the safety of hydrogen charging stations.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.566-572
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• 2020

In a wireless power transmitter, the characteristics and effects of wireless power transmission between two induction coils are investigated, and a power converter circuit and a battery charger/discharger circuit using wireless power transmission technology are proposed. The advantage of wireless power transmitters and wireless chargers is that, instead of the existing plug-in-mounted wired charger (OBC; on-board charger), the user can wirelessly charge the battery without connecting the power source when charging power to the battery. There is. In addition, the advantage of wireless charging can bring about an energy efficiency improvement effect by using the secondary side rectifier circuit and the receiving coil, but the large-capacity long-distance wireless charging method has a limitation on the transmission distance, so many studies are currently being conducted. The purpose of the study is to study the transmitter circuit and receiver circuit of a wireless power transmission device using a primary coil, a secondary coil, and a half bridge series resonance converter, which can transmit power of a non-contact type power transmitter. As a result, a new topology was applied to improve the power transmission distance of the wireless charging system, and through an experiment according to each distance, the maximum efficiency (95.8%) was confirmed at an output of 3 kW at an 8 cm transmission distance.

• Journal of IKEEE
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• v.13 no.1
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• pp.49-56
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• 2009

In this paper, a simulation for the stability of the catenary voltage through charging and discharging by introducing an energy storage system in the railway system and the efficient usage of restoration energy has been performed. In order for the simulation, a simple railway model with an appropriate control technique has been introduced. The catenary voltage area is divided into two areas with voltage control and an area with normal operation and current control is performed to satisfy current limit of the supercapacitor. We confirmed the energy absorption and emission through the simulation and observed energy efficiency through charging and discharging according to the operation state of the railway.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.67-75
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• 2008

The electrostatic charging/discharging mechanism and its effects, and the system design considerations in the space plasma environment are studied in this paper. The electrostatic discharge (ESD) effects are carefully taken into account for a design of the satellite system at the early stage of the development. Generally, the electrical design requirements are specified to protect the satellite system from the ESD effects in the electromagnetic compatibility specifications. Those requirements are included the grounding, the bonding, the shielding, the conductive coating, the electric interfacing and so on. The space charging is caused by the increasing of the voltage difference between the each locations on the satellite surface. If the space charging is continued up to threshold, it may be occurred the system failure. This phenomenon is depended on the mission of system, electrical and mechanical configuration, system operation, and orbit condition. Therefore the related requirements are properly tailored and concentrated into the safety design.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.12
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• pp.511-517
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• 2006

The key issues in high power, high energy applications such as electromagnetic launchers include safety, reliability, flexibility, efficiency, compactness, and cost. To explore some of the issues, a control scheme for a large current wave-forming was designed, built and experimentally verified using a 2.4MJ pulse power system (PPS). The PPS was made up of eight capacitors bank unit, each containing six capacitors connected in parallel. Therefore there were 48 capacitors in total, with ratings of 22kV and 50kJ each. Each unit is charged through a charging switch that is operated by air pressure. For discharging each unit has a triggered vacuum switch (TVS) with ratings of 200kA and 250kV. Hence, flexibility of a large current wave-forming can be obtained by controlling the charging voltage and the discharging times. The whole control system includes a personal computer(PC), RS232 and RS485 pseudo converter, electric/optical signal converters and eight 80C196KC micro-controller based capacitor-bank module(CBM) controllers. Hence, the PC based controller can set the capacitor charging voltages and the TVS trigger timings of each CBM controller for the current wave-forming. It also monitors and records the system status data. We illustrated that our control scheme was able to generate the large current pulse flexibly and safely by experiments. The our control scheme minimize the use of optical cables without reducing EMI noise immunity and reliability, this is resulting in cost reduction. Also, the reliability was increased by isolating ground doubly, it reduced drastically the interference of the large voltage pulse induced by the large current pulse. This paper contains the complete control scheme and details of each subsystem unit.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.275-275
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• 2007

Two sorts of electrode composed of Sulpur/CNT/PVDF and Silver/CNT/PVDF were prepared by in situ chemical method and their electrochemical performance were evaluated by using cyclic voltammetry, impedance measurement and constant-current charge/discharge cycling technique. Also, composite electrodes were characterized by FE-SEM and BET. Raw materials such as CNT/Silver and CNT/Sulfur were mixed in ethanol, dried. These mixed materials were heated at 900 and $320^{\circ}C$ for 2hr, respectively in order to enhance contact among CNT electrodes. Electric double layer capacitor cells were fabricated using these mixed powder with polymer of PVDF. For the charging and discharging characteristics measured at scan rate of 1 mA/s, Supercapacitor of Sulphur-CNT-PVDF electrode showed a better performance than that of Ag-CNT-PVDF, which seems to be related with lower contact resistance of Sulphur-CNT-PVDF electrode.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.1071-1081
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• 2022

As the demand for high-rise buildings increases, the demand for high-speed elevators is also increasing. In order to make a high-speed elevator, a method is needed to reduce the weight of the elevator's components, which is a constraint on the increase in speed. As a measure to reduce the weight, it is possible to remove the traveling cable for power and signal supply. Since the weight of the traveling cable varies depending on the position of the carriage, it is difficult to compensate the weight using the counter weight. The power supply is a structure in which a brush-rail type power input terminal is installed in the elevator hoistway to receive power in a contact-type manner while the carriage is moving. If a small-capacity ESS is installed in a passenger car, power can be supplied uninterruptedly inside the passenger car. A small-capacity ESS charging system to be applied to such an elevator system is required to perform several functions. First, the passenger Car must be able to charge as much as possible even during high-speed operation. A control algorithm with high responsiveness is required because charging starts and ends repeatedly by the partially installed input power stage. In addition, if the input-side line impedance is large due to the structure of the system and the response characteristic is increased, the stability of the system may be lowered. Accordingly, in this paper, we propose a control algorithm that has a stable steady-state output while having a fast response in a transient state. To verify the proposed control algorithm, simulation was conducted using PSIM, and the performance of the controller was verified by manufacturing a prototype buck conveter charger.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.212-215
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• 1995

The thermally stimulated currents (TSC) are measured to know the behaviour of charging particles of epoxy composites at the temperatures range -160~200[$^{\circ}C$] and to prove the various aspects due to hardening time in this study. It is composites at the narrower the magnititude of peak is and hardening time is a degradation from this.