• Smart Structures and Systems
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• v.14 no.4
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• pp.617-641
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• 2014

The energy constraint is still a common issue for the practical application of wireless sensors, since they are usually powered by batteries which limit their lifetime. In this paper, a practical compound energy efficiency strategy is proposed and realized in the implementation of a real time wireless sensor platform. The platform is intended for wireless structural monitoring applications and consists of three parts, wireless sensing unit, base station and data acquisition and configuration software running in a computer within the Matlab environment. The high energy efficiency of the wireless sensor platform is achieved by a proposed adaptive radio transmission power control algorithm, and some straightforward methods, including adopting low power ICs and high efficient power management circuits, low duty cycle radio polling and switching off radio between two adjacent data packets' transmission. The adaptive transmission power control algorithm is based on the statistical average of the path loss estimations using a moving average filter. The algorithm is implemented in the wireless node and relies on the received signal strength feedback piggybacked in the ACK packet from the base station node to estimate the path loss. Therefore, it does not need any control packet overheads. Several experiments are carried out to investigate the link quality of radio channels, validate and evaluate the proposed adaptive transmission power control algorithm, including static and dynamic experiments.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.59-64
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• 2024

In this study, we conducted research on a miniaturized transmission system suitable for ultra-compact electric vehicles, such as electric arts or small electric cars. While conventional electric vehicles eliminate multi-gear transmissions and control motor output or secure initial driving force through reducers, in vehicles like electric karts or compact electric cars, which have relatively small battery capacities, the driving range can be reduced or the motor can be stressed epending on the loading state. Therefore, in this study, we developed a low stage ratio 0.625 and high stage ratio 1.6 a two-stage transmission system that can change gears as needed, considering factors such as slope conditions and loading status, by applying the continuously variable transmission (CVT) mechanism. Based on the selected gear ratios, we designed the transmission and created a test rig to verify the power transmission efficiency of the developed transmission. Using the test rig, we varied the rotational speed and load of the transmission to confirm its power transmission characteristics and also examined the heat generation characteristics during shifting and operation. As a result, developed a two-stage transmission with a CVT structure.

• International Journal of Automotive Technology
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• v.1 no.1
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• pp.42-47
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• 2000

This paper concentrates on the design and construction aspects of a transmission for a mid-class passenger car with internal combustion engine. The transmission, consisting of a Continuously Variable Transmission (CVT) with a Van Doorne V-belt, a planetary gear set and a compact steel flywheel is used to prove the concept of mechanical torque assist. The design goal is to obtain a proof of concept transmission with maximal efficiency, using proven transmission technology. With the developed so called Zero Inertia CVT, the fuel economy of the car is improved by operating the engine at its fuel optimal operating line. To achieve a good vehicle acceleration response, the flywheel assists the powertrain mechanically.

• International Journal of Advanced Culture Technology
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• v.4 no.2
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• pp.27-33
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• 2016

This paper proposes to increase the node energy efficiency, which rapidly drops during the transmission of L-TEEN (Layered Threshold sensitive Energy Efficient sensor Network protocol), using the method of DL-TEEN (Dual-hop Layered TEEN). By introducing dual-hop method in the data transmission, the proposed single-hop method for short-range transmission and multi-hop transmission method between the cluster heads for remote transmission was introduce. By introducing a partial multi-hop method in the data transmission, a single-hop method for short range transmission method between the cluster heads for remote transmission was introduces. In the proposed DL-TEEN, the energy consumption of cluster head for remote transmission reduces and increases the energy efficiency of sensor node by reducing the transmission distance and simplifying the transmission routine for short-range transmission. As compared the general L-TEEN, it was adapted to a wider sensor field.

• International journal of advanced smart convergence
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• v.5 no.2
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• pp.24-37
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• 2016

This paper proposes to increase the efficiency of energy in nodes, which rapidly drops during the transmission of the Low Energy Adaptive Clustering Hierarchy (LEACH), through the use of dual-hop layered application in the sensor field. Along with introducing the dual-hop method in the data transmission, the proposed single-hop method for short-range transmission and multi-hop transmission method between the cluster heads for remote transmission were also introduced. Additionally, by introducing a partial multi-hop method in the data transmission, a single-hop method for short range transmission method between the cluster heads for remote transmission was used. In the proposed DL-LEACH, the energy consumption of the cluster head for remote transmission reduced, as well as increased the energy efficiency of the sensor node by reducing the transmission distance and simplifying the transmission route for short-range transmission. As compared the general LEACH, it was adapted to a wider sensor field.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.342-348
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• 2013

It proposes an efficient control algorithm to increase electric power transmission efficiency between photovoltaic power generating system and the grid. The main controller finds a maximum efficiency condition by considering the quantity of power generated from PV arrays, the number of inverters, and efficiency of PV inverter. According to the condition, a relay board arranges a point of contract of PV arrays. By the disposition of PV arrays, it assigns the optimized power on each PV inverter. Operational principle of the proposed maximum efficiency point tracking algorithm is given in detail. To verify the validity of the proposed approach, computer-aided simulation and experiment carried out.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.30-36
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• 2018

Automotive fuel efficiency regulations and air pollution control are hot issues of recent years in the automotive industry. To solve these regulation problems, many studies are continuing to improve the transmission efficiency of transmissions. Tapered roller bearings are useful to improve the transmission efficiency in the recent automobile parts. The frictional losses in the tapered roller bearings are mainly composed of the rolling friction and the sliding friction, and are dependent upon the load, the lubrication, the rotation speed of bearings, and etc. In this paper, the operating conditions of the transmission are defined and then the power losses of each bearing are calculated. In addition, improvement options are suggested after identifying the design factors influenced much by the improvement effect of power loss under the operating conditions of each bearing. We compare the power losses of the entire transmission system due to bearing improvements by comparing the friction losses between the original design and the improved design. Lastly, it is shown that the calculated power losses are valid by comparing the test values and the theoretical values for the frictional torque characteristics of the original and improved bearings.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.4
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• pp.47-53
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• 2015

The electrical safety and efficiency is the most important thing of the electric vehicle charging system. The prior system is contact charging system that is contacted directly by human. So, it has riskiness such as electric shock in the case of poor insulation or contact problems. To solve these safety issues and the convenience problems, a wireless power transmission system has been developed and is currently in trial operation. However, because high frequency is used in wireless power transmission system instead of commercial frequency, we need to apply protection measures concerning electric shock and equipment protection. Also, it should be accompanied by measuring efficiency for the effective operation of the wireless power transmission system. Therefore, we structured monitoring system in trial operation area of wireless power transmission system and applied decision algorithm for protection of human and equipment and economic operation of it.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11C
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• pp.1059-1066
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• 2009

In this paper, we propose the precoder with superimposed pilots for orthogonal frequency-division multiple access (OFDMA) systems in order to enhance the transmission efficiency of the system and reduce peak-to-average power ratio (PAPR) which is the problem in OFDMA uplink. In wireless communication systems, the way to improve transmission efficiency is 1) to reduce bit error rate (BER) or 2) to increase data rate. In the proposed scheme, we design the precoder and superimposed pilots in the transmitter and use them in the receiver for increasing data rate, caused by the saved transmission bandwidth thanks to the superimposed pilots. In addition, we improve BER performance with the help of the frequency diversity gain caused by precoding. Also using superimposed pilots, we enhance the PAPR performance by increasing the average output power of the signal.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_3
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• pp.1223-1231
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• 2023

In the case of internal combustion engine vehicles, transmissions are essential for various reasons, such as vehicle starting and speed control. However, in the case of electric vehicles, unlike internal combustion engine vehicles, a transmission is not necessarily required. Of course, considering the efficiency of electric vehicles, a transmission is necessary, but installing the existing transmission as is has the opposite effect due to increased vehicle weight, so it has not been considered so far. In this paper, a non-contact reducer type using the Arago disc effect is proposed rather than a transmission using a conventional gear train, and the aim is to examine whether this can increase the driving efficiency of electric vehicles while minimizing weight. In addition, the effectiveness of the proposed reducer will be verified by manufacturing and testing it.