• Journal of the Semiconductor & Display Technology
• /
• v.20 no.2
• /
• pp.29-33
• /
• 2021

A 5.8-GHz 1W wireless power transmission system was used for charging a smart phone. The voltage of one RF power receiver with antenna was not enough for charging. Several power receivers for charging a smart phone was connected serially. The voltage of several RF power receivers are highly enough for charging a smart phone within 50cm. However, the lack of current from small capacitances of RF-DC converters is not suitable for charging smart phone. It means very long charging time. In this paper, the voltage multiplier circuits for RF-DC converters were analyzed to increase the current and voltage at the same time to reduce the charging time in smartphone RF wireless charging. Through the analysis of multiplier circuits, the 7-stage parallel multiplier circuit with voltage-doubler units are suitable for charging the smartphone, which supplies 5V and 700mA at 3V@5.8GHz.

• Journal of the Semiconductor & Display Technology
• /
• v.20 no.2
• /
• pp.25-28
• /
• 2021

In this paper, we studied smart phone RF wireless charging with 5.8-GHz microwave wireless power receiver. The dc output of the receiver connected to super capacitor and DC-DC converter for charging a smart phone. This configuration stably supplies 5V and current for charging it. Studies show that the more receivers are used at close range, the higher the received voltage values and the larger the capacity of the super capacitor, the longer the charging time. The present 5.8-GHz 1W wireless power transmission system is not enough for charging a smartphone mainly due to the lack of current of the receiver.

• Journal of the Semiconductor & Display Technology
• /
• v.20 no.3
• /
• pp.136-139
• /
• 2021

In this paper, we studied the charging characteristics of high-capacity supercapacitor with high current for RF wireless charging system for smart phone charging. The dc output of the RF-DC receiver is connected to supercapacitor after which is connected to DC-DC converter for charging a smart phone. This configuration stably supplies voltage and current for charging it. Studies show that the higher charging current use, the rapidly shorter the charging time of supercapacitor is. The currents of 2A, 10A and 27A were used for charging supercapacitors. The charging time was measured for 3000F, 6000F, 12000F supercapacitors which is parallelly connected with 3000F supercapacitors.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.4
• /
• pp.607-614
• /
• 2017

In this research, buck converter was designed and manufactured to improve the wireless charging of smartphone through PWM control technology based on micro controller. A feedback control circuit was fabricated using a voltage sensor so that the output voltage follows the reference voltage. The buck converter, 311V is output as 12V, DC voltage 12V is connected wirelessly, and 5V charge voltage is output. We also confirmed the availability of the buck converter for wireless charging of smart phone through experiments.

• Journal of Advanced Navigation Technology
• /
• v.21 no.6
• /
• pp.620-625
• /
• 2017

Recently, the solar module for charging internet devices is installed in crowded areas to offers services so that people can charge their smartphones or tablets. But this charging module can not be linked with the information related to a bus approach so people are subject to let their belongings such as smartphone, tablet pc at the bus stop while they are still charging it. This paper proposes a system to inform the smart phone when the bus is accessed by using the LPWA technology and BLE technology to resolve such under-failures. This experimental result showed that the power usage of LPWA based bus entry systems is an average of X, confirming that the long period usage of low-power can be possible for low power consumption in this results, enabling information on the bus to be transmitted to smart phones using Advertising mode of BLE.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.4
• /
• pp.149-154
• /
• 2020

This paper presented a design and a implementation of prototype model which is the smart diffuser device controlled by using Bluetooth technology in the smart phone. We used the ultrasonic waves oscillator so that the smart diffuser was able to spray oil into a device. The device was developed to find out the high brightness led colors switched during spraying the oil. By using the Li-Po battery of 40mAh capacity, we were able to design this portable device was prolonged available time to use and to solve the charging time problem. We realized the availability of prototype model which is using the Bluetooth Low Energy for operating the low power driving.

• Electronics and Telecommunications Trends
• /
• v.31 no.3
• /
• pp.32-41
• /
• 2016

2008년부터 smart phone과 같은 휴대기기의 무선충전을 목표로 지속적인 발전을 거듭해온 무선충전 기술은 2015년 마침내 smart phone에 기본으로 장착되기에 이르렀으며, 특히 최근 스마트워치 등의 웨어러블 기기의 등장으로 기술발전과 다양화가 한층 더 가속화되고 있다. 최근 무선충전 기술은 기존의 2차원 패드 구조에서 벗어나 더욱 높은 자유도와 안전성을 부여하기 위한 노력을 하고 있고, 유선충전에서 적용되고 있는 고속 충전 기술을 무선충전에 적용하기 위한 기술개발을 병행하고 있다. 본고에서는 이러한 무선충전기술의 발전 동향과 표준화 동향을 소개하고, 향후 무선충전기술의 발전 방향에 대해 논하고자 한다.

• Journal of Advanced Navigation Technology
• /
• v.20 no.1
• /
• pp.86-92
• /
• 2016

Recently, solar module is installed in crowded areas to offers services so that people can charge their smartphones or tablets. However, the burden in terms of cost is high to install in areas where utilization ratio is low and installation is difficult in limited spaces. In this paper, a system for collecting and providing the optical power is proposed from the analysis about the person that receives service in each area using the real-time data provided by the state and collected from the actual environment as well as considering the waiting time and the solar charging time in different environments. As a result, This study shows that charge was not delayed since collecting power exceeds charging power. Smartphone was fully charged in ninety-five minutes. we confirmed that with one smartphone, it can be charged a approximately fifty percent of the battery in between ten to twenty minutes, with multiple units they can be charged a approximately twenty percent of the battery in between ten to twenty minutes.

• Journal of Convergence Society for SMB
• /
• v.5 no.2
• /
• pp.15-20
• /
• 2015

Recently, as smart phone technology is developing, wearable devices is also accelerating. But, the wearable device is necessary to operated for a long time with a small electric power because werable device is made compact. In this paper, we design and implement efficient lithium polymer battery model suitable to miniaturized wearable device in oder to maximize ease of use. The proposed model is characterized by a compact size of the battery by applying a thermal element and a light-weight battery. Also, proposed model gives greatly improve the life of wearable devices because it uses a method using the characteristics of the Peltier device using the temperature difference between the room temperature and body temperature of a person to generate power for charging. In particular, the proposed model can be used for the wearable device, as well as auxiliary charging of the smart phone.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.67 no.3
• /
• pp.160-167
• /
• 2018

In this paper, a black box, which is provided the reliability and user safety of home battery energy storage system connected with solar energy generation, is developed. In the developed scheme, a status and diagnosis data of battery management system, power conditioning system, solar energy generation and grid is measured. This status and diagnosis data is stored and displayed in the developed black box. In addition, this status and diagnosis data is stored and displayed in a monitoring system and a smart phone of user. A performance evaluation of the developed black box is carried out using emulator of home battery energy storage system connected with solar energy generation. Consequently, the developed black box is proved its superiority of the reliability and user safety.