• ETRI Journal
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• v.34 no.2
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• pp.268-271
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• 2012

The high peak-to-average power is one of the main drawbacks in OFDM systems. This letter proposes a partial shift mapping (PSM) method for peak power reduction in OFDM systems. By utilizing the properties of the discrete Fourier transform, the proposed method generates a set of candidate signals without additional complex multiplication and selects the one with minimum peak power for transmission. Analyses and simulations confirm that the PSM method achieves satisfactory peak power reduction performance and low complexity compared with other kindred methods, for example, selected mapping and partial transmit sequences.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.5
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• pp.1735-1754
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• 2022

The reliability and performance of WiFi need optimization because of the rising number of WiFi users day by day. A highlighted point is saving power while transmitting and receiving packets using WiFi devices. Wake-on-Wlan (WoW) is also implemented to improve energy consumption, but it also needs betterment. This paper will introduce universal ideas to transmit and receive packets using low-power technology like Bluetooth or BLE (Bluetooth low energy). While looking for power-saving ways in this research, WiFi connection and maintenance also take care using lesser power-consuming technology. Identifying different use-cases where low power technology can help save energy and maintain 802.11 connection is part of the research. In addition, the proposed method discuss energy saving with unicast and broadcast/multicast data. Calculation of power-saving and comparison with standalone WiFi usage clearly shows the effectiveness of the proposed method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.213-218
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• 2017

High-voltage power systems operate in order to generate and transmit electric power at power stations. Compared to low-power systems, high-power systems are complex in structure, large-scale, and expensive. When high-power cable accidents occur, most facilities are incapacitated-including low-power systems-causing huge economic losses. Great care must therefore be taken in designing, installing and managing power systems. Although dependent on installation circumstances and usage conditions, in some cases the cross-sectional areas of cables fall short of the critical area due to the expansion of and improper design and installation of power facilities. In this situation, the exceeded ampacity (allowable current) above the critical value caused by the operating current initiates the deterioration processes of power cables. In order to systematically monitor power cables operating at power stations, we have developed the first device of its kind in Korea. In this paper, we present the analyzed characteristics of expected temperatures of cables based on the load current of high-voltage cables operating at Korean Western Power Co. Ltd. We can predict the lifetime of cables by analyzing the temperature obtained from our device.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.253-256
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• 2000

This paper describes a DSP implementation of a real-time 3D sound localization algorithm with the use of a low power embedded DSP. A distinctive feature of this implementation is that the audible frequency band is divided into three, in accordance with the sound reflection and diffraction phenomena through different media from a certain sound source to human ears, and then in each subband a specific implementation procedure of the 3D sound localization is devised so as to operate real-time at a low frequency of 50MHz on a 16bit fixed-point DSP. Thus out DSP implementation can provide a listener with 3D sound effects through a headphone at low cost and low power consumption.

• Journal of Information Processing Systems
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• v.10 no.3
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• pp.412-428
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• 2014

Request oriented sensor networks have stricter requirements than conventional event-driven or periodic report models. Therefore, in this paper we propose a minimum energy data aggregation (MEDA), which meets the requirements for request oriented sensor networks by exploiting a low power real-time scheduler, on-demand time synchronization, variable response frame structure, and adaptive retransmission. In addition we introduce a test bed consisting of a number of MEDA prototypes, which support near real-time bidirectional sensor networks. The experimental results also demonstrate that the MEDA guarantees deterministic aggregation time, enables minimum energy operation, and provides a reliable data aggregation service.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.353-359
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• 2014

Recently, the use of mobile devices has increased, and mobile traffic is growing rapidly. In order to deal with such massive traffic, cognitive radio (CR) is applied to efficiently use limited-spectrum resources. However, there can be multiple communication systems trying to access the white space (unused spectrum), and inevitable interference may occur to cause mutual performance degradation. Therefore, understanding the effects of interference in CR-based systems is crucial to meaningful operations of these systems. In this paper, we consider a long-term evolution (LTE) system using additional spectra by accessing the TV white space, where low-power devices (LPDs) are licensed primary users, in addition to TV broadcasting service providers. We model such a heterogeneous system to analyze the co-existence problem and evaluate the interference effects of LPDs on LTE user equipment (UE) throughput. We then present methods to mitigate the interference effects of LPDs by 'de-selecting' some of the UEs to effectively increase the overall sector throughput of the CR-based LTE system.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.431-437
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• 2012

PV simulators are essential equipment for testing power conditioning systems (PCS) which are one of an important part in PV generator systems, for testing before shipment. High dynamic PV simulator is required since MPPT(Maximum Power Point Tracking) test procedure has been established by EN50530 regulation recently. Most high quality PV simulator prevailed in the market is linear type which however has low efficiency. This paper proposes design guide lines for the power stage and LCL type filter cooperating with a switching mode PV simulator that shows high efficiency and very low power consumption. Proposed theory is verified by experiment.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1982-1985
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• 2003

Future cellular networks will mainly be driven by, high quality channels, high band with utilization, low power consumption and efficient network management. For a given channel allocation, the capacity and quality of communication of cellular radio systems using CDMA(Code Division Multiple Access) can be increased by using a transmitter power control scheme to combat the near-far problem. Centralized power control schemes or distributed ones to maximize the minimum signal-to-interference in each user of CDMA wireless network have been investigated. This paper has proposed a distributed power control algorithm, which employs an adaptive search scheme, in order to solve quickly the linear systems of equations for power update in CDMA cellular radio systems. The simulation results show that the proposed scheme has faster convergence rate than the typical bang-bang type of distributed power control algorithm, which has been much used as a reference algorithm in IS-95A and W-CDMA communication network.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.191-196
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• 2014

For the large scale of electricity consumer, since the price for the electricity consumption depends on the peak power, the issue for peak power reduction have been being studied widely. Electric railway systems, which is one of the most representative large scale of loads, also has assignment to reduce the peak power since they have high peak power and low energy consumption load characteristics. In the aspect of the economic operation through reduction of peak power, this paper proposes a novel algorithm for power management system in electric railway systems using energy storage.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.10
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• pp.213-220
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• 2020

The power consumption and performance of hardware-based mobile and IoT embedded systems that require high specifications are one of the important issues of these systems. In particular, the problem of excessive power consumption is because it causes a problem of increasing heat generation and shortening the life of the device. In addition, in the same environment, software also needs to perform stable operation in limited power and memory, thereby increasing power consumption of the device. In order to solve these issues, we propose a Low level power improvement via identifying performance dissipation. The proposed method identifies complex modules (especially Cyclomatic complexity, Coupling & Cohesion) through code visualization, and helps to simplify low power code patterning and performance code. Therefore, through this method, it is possible to optimize the quality of the code by reducing power consumption and improving performance.