• International Journal of Internet, Broadcasting and Communication
• /
• v.14 no.4
• /
• pp.80-87
• /
• 2022

Lack of sufficient battery capacity is one of the most important challenges impeding the development of wireless sensor networks (WSNs). Recent innovations in the areas of wireless energy transfer and rechargeable batteries have made it possible to advance WSNs. Therefore, in this article, we propose an energy-efficient charging of sensors in a WSN scenario. First, we have formulated the problem as an integer linear programming (ILP) problem. Then a utility function-based greedy algorithm named UGreedy/UF1 is proposed for solving the problem. Finally, the performance of UGreedy/UF1 is analyzed along with other baseline algorithms: UGreedy/UF2, 2-opt TSP, and Greedy TSP. The simulation results show that UGreedy/UF1 performs better than others both in terms of the deadline missing ratio of sensors and the total energy consumption of UAVs.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.6
• /
• pp.455-463
• /
• 2022

This study proposes a receiving pad identification coil for wireless charging of electric vehicles. The proposed coil identifies the shape of the receiving pad through magnetic coupling with the receiving pad. Therefore, the shape of the coil is designed to show the different magnetic properties of each receiving pad. The accuracy of this design is verified through finite element method simulation. Furthermore, the operation method of the secondary pad identification circuit is described, and the appropriate magnitude and length of the pulse voltage applied to this circuit for receiving pad identification are derived through simulation. The performance of the proposed identification coil set is verified by the experimental results.

• Ceramist
• /
• v.22 no.4
• /
• pp.402-416
• /
• 2019

The development of next-generation secondary batteries, including lithium-ion batteries (LIB), requires performance enhancements such as high energy/high power density, low cost, long life, and excellent safety. The discovery of new materials with such requirements is a challenging and time-consuming process with great difficulty. To pursue this challenging endeavor, it is pivotal to understand the structure and interface of electrode materials in a multiscale level at the atomic, molecular, macro-scale during charging / discharging. In this regard, various advanced material characterization tools, including the first-principle calculation, high-resolution electron microscopy, and synchrotron-based X-ray techniques, have been actively employed to understand the charge storage- and degradation-mechanisms of various electrode materials. In this article, we introduce and review recent advances in in-situ synchrotron-based x-ray techniques to study electrode materials for LIBs during thermal degradation and charging/discharging. We show that the fundamental understanding of the structure and interface of the battery materials gained through these advanced in-situ investigations provides valuable insight into designing next-generation electrode materials with significantly improved performance in terms of high energy/high power density, low cost, long life, and excellent safety.

• Journal of the Korean Institute of Educational Facilities
• /
• v.15 no.5
• /
• pp.21-32
• /
• 2008

The major issues that higher education has recently faced are the shortage of students of school age, the changing environment of higher education and the evolving technology. These challenges have urged the university facilities and space to be managing more efficient and more effective. This study assures that the strong strategy is to operate more like business while retaining unique higher education values and a sound facilities management system and appropriate budget help to ensure that university facilities are good for student and teacher's demand. With such faith, this study explores the facilities/space maintaining status and the facility management system of national universities and collages. It finds that there are some problems to adapt new managing methodologies in national universities and that there are also some gaps and perceived constraints to effective space management. This study proposes the alternatives for the facilities managing system that involves the improvement of manpower structure, the expansion of budget scale and the establishment of appropriate facility management system. Finally it provides the practical tools for the effective space and facilities management such as space charging, space standards, central timetabling, space utilisation survey and facilities performance indication.

• Journal of the Korean Society for Precision Engineering
• /
• v.33 no.12
• /
• pp.1015-1020
• /
• 2016

An advantage of electric vehicles is that they are environmentally sustainable because they do not emit exhaust gases, such as $CO_2$ or Nox. A disadvantage is the low power performance of the motor and battery source, necessitating a reduction in the weight of the vehicle to increase efficiency. Another disadvantage is that the rechargeable battery enables an electric vehicle to only run for a limited number of miles before requiring electric charging. To solve these problems, the hybrid vehicle has been developed by combining environmental sustainability with the high performance of a conventional internal combustion engine. In this study, an electric UTV (Utility Terrain Vehicle) was transformed into a hybrid vehicle system by outfitting the vehicle with a drive auxiliary power system including a 125 cc internal combustion engine. This modification enabled us to extend the range of the hybrid UTV from 50km to 100km per one electric charging.

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.352-356
• /
• 2006

As a basic study to develop heating panel, the purpose of this study was to know possibility as a floor heating panel. We investigated working conditions and performance of pulsating heat pipe. Tests were conducted under the next conditions; Working fluid were R-22 and R-134a, charging ratio 40% and 50%, temperature of inlet water $60^{\circ}C$ and $70^{\circ}C$, flow rates $1{\sim}3kg/min$. The experimental results indicate that the pulsating heat pipe charged 50% showed better performance than 40%, R-22 is more suited to the working fluid than R-134a, and it has a possibility which can be applied to floor heating panel using a pulsating heat pipe.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.7
• /
• pp.48-55
• /
• 2019

Soldiers have been exposed to the risk of chilblains in cold winters. Recent studies have described sensors and IOT devices that use independent power sources based on piezoelectric energy harvesting. Therefore, the heated shoes with an independent power source have been developed. For the application of energy harvesting to shoes, it is necessary to develop a unique harvester by considering human gait characteristics. Energy harvesters and ceramics were designed and fabricated in this study. The performances of these harvesters and ceramics were evaluated experimentally. Then, the harvesters and ceramics with superior performance were selected and applied to the system. Thereafter, the heating and charging performance of the system was tested under real walking conditions. The results show that the developed system can generate adequate energy to charge the battery and heat the shoes.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.265-266
• /
• 2010

This paper propose the test method for performance of myoelectric hand prosthesis(MHP) according to myoelectric signal generated in the human muscle. The MHP consists of a mechanical hand, a surface myoelectric sensor(SMES) for measuring myoelectric signal, a control system and a charging battery. The propose test method is proved the reliability of MHP.

• 한국전기화학회:학술대회논문집
• /
• 1999.11a
• /
• pp.137-146
• /
• 1999

The rechargeable alkaline manganese dioxide(RAM)battery system has reached a performance level that enables the consumer to utilize RAM for practically all applications where currently single use cells(alkaline manganese, zinc-carbon)are being used. In addition, it can replace nickel-cadmium and nickel-metal hydride cells in low to medium power applications with much improved charge retention at higher operating temperatures and in intermittent use and works well with solar charging. A review is given on RAM cell performance as well as a comparison to competing rechargeable technologies. Potential new possibilities in the field of OEM(original equipment manufacturer) applications are discussed.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.3
• /
• pp.240-248
• /
• 2016

As a new technical approach, the achievement of an eco-environmental leisure boat with a photovoltaic system is attempted by simultaneously actuating nine photovoltaic solar panels, in association with an applied sail control system by use of wind. In this approach, the photovoltaic system consists of a solar module, an inverter, a battery, and relevant components, while the sail control device is equipped with a sail up/down and mast-turning instrument. Furthermore, this research conducts a performance evaluation of the manufactured prototype and acquires the purposed quantity value and the development purpose items. The significant items-sail up/down speed (seconds) and mast turning angle (degrees)-are evaluated during the performance test. In the process of the performance evaluation, a wind direction sensitivity of 90% and a maximum instant charging power of 900 W were also obtained. In addition, the maximum sail time is evaluated in order to acquire the optimum quantity.