• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.5-6
• /
• 2014

According to 2013 fire statistical yearbook in the National Emergency Management Agency, the main cause of an electrical fire are classified to short circuit fault, overload fault, electric leakage, partial disconnection, and joint/contact badness. The occurrence factor of fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Devices(RCDs) of high sensitivity type used at single phase (220V) cut off earth leakage and overload but the RCDs can not cut off electric arc or spark to be a main cause of electrical fire. To be improved on such problem, this thesis is proposed to a auxiliary control device for RCD cut off electric arc or spark.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1368-1370
• /
• 2005

Satellite is operated only with internal battery when separated from rocket. Internal battery is charged only from SAR(solar Array Regulator), solar cell. So battery will be exhausted and purpose of satellite will be failed if load module is out of order or short. This paper proposed real time current limiter which operated by telemetry of outer processor. This current limiter operates by control signal simultaneously cuts off over current by self over current sensing circuit. So it can reduce waste of battery energy and over load of outer processor.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.8
• /
• pp.869-874
• /
• 1999

In this paper, electrochemical techniques are used to investigate hydrothermal-electrochemically formation of barium titanate (BT) ceramic films. For comparison, the electrochemical behaviors of anodic titanium oxide films formed in alkaline solution were also investigated both at room temperature and in hydrothermal condition at 150.0 ℃. Film structure and morphology were identified by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Titanium oxide films produced at different potentials exhibit different film morphology. The breakdown of titanium oxide films anodic growth on Ti electrode plays an important roles in the formation of BT films. BT films can grow on anodic oxide/metal substrate interface by short-circuit path, and the dissolution-precipitation processes on the ceramic film/solution interface control the film structure and morphology. Based upon the current experimental results and our previous work, extensively schematic proce-dures are proposed to model the mechanism of ceramic film formation by hydrothermal-electrochemical method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.1
• /
• pp.58-63
• /
• 2019

Lithium-ion batteries used for IT, automobiles, and industrial energy-storage devices have battery management systems (BMS) to protect the battery from abnormal voltage, current, and temperature environments, as well as safety devices like, current interruption device (CID), fuse, and vent to obtain positive temperature coefficient (PTC). Nonetheless, there are harmful to human health and property and damage the brand image of the manufacturer because of smoke, fire, and explosion of lithium battery packs. In this paper, we propose a systematic protection algorithm combining battery temperature, over-current, and interconnection between protection elements to prevent copper deposition, internal short circuit, and separator shrinkage due to frequent and instantaneous over-current discharges. The parameters of the proposed algorithm are suggested to utilize the experimental data in consideration of battery pack operating conditions and malicious conditions.

• Journal of the Semiconductor & Display Technology
• /
• v.17 no.3
• /
• pp.104-107
• /
• 2018

In this paper, we developed a sensor for monitoring the leakage current through the chassis of the robot. The leakage current sensor needs to be developed because it is a necessary part to prevent electric shock accidents that may occur through the chassis of a robot or an electric vehicle. This leakage monitoring sensor was developed to be mounted directly on the chassis of the robot. This sensor protects the control system from noise by discharging static and high-frequency noise that may occur in the chassis of the robot and monitors the leakage current by measuring the amount of current discharged through the ground. In this paper, a leakage monitoring sensor was developed with a simple structure using resistors, capacitors and OP-AMP, and the performance was evaluated.

• Proceedings of the KIPE Conference
• /
• 2018.11a
• /
• pp.9-11
• /
• 2018

This paper studies on the development of an electric fire prevention system with the detection and alarm in case of parallel arc fault occurrence in low voltage distribution lines. The proposed detector has the characteristics of high speed operation responsibility and superior system reliability from composition using a large number of semiconductor devices. The line voltage is always feedback, and when an arc or a spark occurs, these are detected by the microcomputer. In addition, we design and develop algorithms using high speed and high precision microcomputer. A new conceptual control technique is adopted that RCD cuts-off by forming a forced short circuit between the phase voltage and ground in the event of an electrical accident. Some experimental tests of the proposed system also confirm practicality and the validity of the analytical results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.24 no.2
• /
• pp.127-133
• /
• 2019

This paper proposes a restarting method for extended electromotive force (EEMF)-based sensorless permanent magnet synchronous motor (PMSM) drive systems. The sensorless PMSM drive systems generally estimate the rotor speed and angle based on EEMF. However, if the inverter is stopped while the PMSM is rotating, the initial rotor speed and angle are required for restart. Therefore, the proposed restarting method estimates the initial rotor speed and angle using the short-circuit current generated by applying zero voltage vector from the inverter. The validity of the proposed method is verified by simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.6
• /
• pp.411-420
• /
• 2021

In this paper, bidirectional LLC-LC resonant DC-DC converter with notch filters in the primary side of resonant circuits is proposed. Even if resonant capacitors are used on the primary and secondary sides, the proposed converter can operate with the high gain characteristics of the LLC resonant converter without mutual coupling of resonant capacitors, regardless of the direction of power flow. In addition, by applying notch filters, the proposed converter can operate with a wider gain control range and can cope with overload and short circuit. The analysis and operating characteristics of the proposed bidirectional LLC-LC resonant converter are investigated. A 3.3 kW prototyped bidirectional LLC-LC resonant converter connected to 750 V_DC buses is designed and tested to verify the validity and applicability of this proposed converter.

• Current Photovoltaic Research
• /
• v.10 no.1
• /
• pp.23-27
• /
• 2022

In this study, we investigate organic-inorganic halide perovskite solar cells with a vacuum thermal evaporated hole transporting layer (NPB/MoO_3-x). By replacing solution process based Spiro-MeOTAD with vacuum thermal evaporation based NPB/MoO_3-x, a thin hole transporting layer was implemented. In addition, parasitic absorption that may occur during the doping process was eliminated by excluding solution process doping. In a solar cell with a thin vacuum thermal evaporated hole transporting layer, the short-circuit current density (Jsc) increased to 23.93 mA/cm², resulting in the highest power converstion efficiency (PCE) at 18.76%. Considering these results, it is essential to control the thickness of hole transporting layer located at the top in solar cell configuration.

• Journal of Information Technology Applications and Management
• /
• v.26 no.6
• /
• pp.103-117
• /
• 2019

Demand for high power motors is rapidly increasing as the 4th industry and convergence technology has recently emerged. In order to produce high-strength permanent magnets, the magnets used for magnetization have been increased from DC 300V in the 1970s to DC 2.5kV in the 2010s, Up to DC 10kV in the 2030s, It is expected that higher voltage will be used to magnetize. However, in the case of a magnetizer using an existing electric signal control device, it is necessary to use a control device with a high-voltage insulation function in case a high voltage used for magnetization is leaked to the control device. If a short circuit accident occurs, the controller must be shut down and serious problems such as excessive repair costs arise. In this study, a control system adopting optical communication method instead of electric signal control method is proposed to prevent leakage currents in high-voltage magnetizer. We design a transmitter(Tx) and a receiver(Rx) device for the optical communication control device and implemented a prototype connecting the optical cable. In order to demonstrate the utility of high-voltage magnetizer using the optical communication control device, we analyzed the initial cost and the yearly cost for the years to analyze the net present value. As a result, In the case of the low-voltage magnetizer, the electric signal control method cost less, As the operating voltage of the magnetizer becomes higher. It is confirmed that it takes less cost when the optical communication control device is used.