• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.10
• /
• pp.895-906
• /
• 2015

This paper presents a methodology and a model that can analyze the high frequency transfer characteristics from socket in the AC power port to the 5 V DC output port in the mobile charging circuit. This is to predict the output signals coming from the IEC(International Electrotechnical Commission) Standard(IEC 61000-4-4), EFT/B(Electric Fast Transient and Burst) immunity test for mobile charging circuit. Since the mobile charging circuit is energized from the AC power socket from the power line, it is necessary to know the high frequency transfer characteristics with activated AC power line. A simple CDN(Coupling-Decoupling Network) is designed and manufactured for measuring S-parameters of mobile charging circuit with and without AC power line activated. The result shows that the S-parameters of the specific mobile charging circuits are almost the same, independent of AC power line activation. Consequently, the S-parameters without AC line could be used to predict the output response to the EFT/B signals, and it was shown that the proposed methodology predicts the output responses quite accurately, which proves the validness of the methodology presented in this paper.

• Journal of Sensor Science and Technology
• /
• v.27 no.2
• /
• pp.86-92
• /
• 2018

In recent times, motion capture technology using inertial measurement unit (IMU) sensors has been actively used in sports. In this study, we developed a canoe paddle, installed with an IMU and a water level sensor, as a system tool for training and calibration purposes in water sports. The hardware was fabricated to control an attitude heading reference system (AHRS) module, a water level sensor, a communication module, and a wireless charging circuit. We also developed an application program for the mobile device that processes paddling motion data from the paddling operation and also visualizes it. An AHRS module with acceleration, gyro, and geomagnetic sensors each having three axes, and a resistive water level sensor that senses the immersion depth in the water of the paddle represented the paddle motion. The motion data transmitted from the paddle device is internally decoded and classified by the application program in the mobile device to perform visualization and to operate functions of the mobile training/correction system. To conclude, we tried to provide mobile knowledge service through paddle sport data using this technique. The developed system works reasonably well to be used as a basic training and posture correction tool for paddle sports; the transmission delay time of the sensor system is measured within 90 ms, and it shows that there is no complication in its practical usage.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.9
• /
• pp.713-722
• /
• 2017

In the future battlefield, the role of the unmanned vehicle is very important. Currently, charging and management systems for unmanned vehicles are all wired. However, for convenience and stability, it is desirable that the charging of the unmanned vehicle uses wireless power transfer system. In this paper, we have studied the application of wireless power transfer system to the charging of unmanned vehicles. Considering the size of the unmanned vehicle and the required power, the transmission coil and the receiving coil are designed through the finite element analysis based magnetic field simulation. The coil was made according to the simulation results and the circuit simulation was performed through the measured parameter values. Finally, we show that wireless power transmission can be applied to unmanned mobile charging through actual experiments.

• Journal of Sensor Science and Technology
• /
• v.18 no.1
• /
• pp.28-32
• /
• 2009

Most portable mobile devices employ rechargeable lithium-ion batteries. This lithium-ion battery usually suffers from the possibility of explosion due to heat generation from surrounding atmosphere or internal deficiency during charging or at overuse. To solve these problems, most rechargeable batteries have a built-in protection circuit module (PCM). The resistance of a properly processed $VO_2$ critical temperature sensor (CTS) is changed dramatically at a critical temperature of around $68^{\circ}C$, which can replace some bi-metal, NTC, or PTC sensors embedded in PCM. Such $VO_2$ CTS consumes a very small current at the level of natural discharge. Experimental results showed that this CTS could be applied to a PCM as the PCM could protect the battery while keeping its power consumption at minimum.

• Journal of Industrial Technology
• /
• v.40 no.1
• /
• pp.13-18
• /
• 2020

Lithium-ion batteries have a small volume, light weight and high energy density, maximizing the utilization of mobile devices. It is widely used for various purposes such as electric bicycles and scooters (e-Mobility), mass energy storage (ESS), and electric and hybrid vehicles. To date, lithium-ion batteries have grown to focus on increasing energy density and reducing production costs in line with the required capacity. However, the research and development level of lithium-ion batteries seems to have reached the limit in terms of energy density. In addition, the charging time is an important factor for using lithium-ion batteries. Therefore, it was urgent to develop a high-speed charger to shorten the charging time. In this thesis, a discharger was fabricated to evaluate the capacity and characteristics of Li-ion battery pack which can be used for e-mobility. To achieve this, a smart discharger is designed with a combination of active load, current sensor, and temperature sensor. To carry out this thesis, an active load switching using sensor control circuit, signal processing circuit, and FET was designed and manufactured as hardware with the characteristics of active discharger. And as software for controlling the hardware of the active discharger, a Raspberry Pi control device and a touch screen program were designed. The developed discharger is designed to change the 600W capacity battery in the form of active load.