• 전기학회논문지
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• 제57권10호
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• pp.1790-1795
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• 2008

Energy scavenging is a technique that converts ambient energy, for example, vibration and light, to electrical energy in order to supply power to low power electronic devices such as ubiquitous sensors. In this paper, we propose an optimal operation condition of power delivery circuit and design strategy for energy scavenging system in which the generated power is order of microwatt and, consequently, efficient handling of power is critical. We also propose that high data transmission rate is more realistic optimal design objective rather than high energy efficiency. It is shown that disconnection of load from the storage capacitor right after data transmission reduces energy wasting and that optimal value of storage capacitor can be determined at this condition. The feasibility of our propose is proved by experiments and we believe that the proposed design strategy will promote the application of piezoelectric micropower generator to the ubiquitous sensor networks.

• 한국통신학회논문지
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• 제41권11호
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• pp.1589-1597
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• 2016

본 논문에서는 사막, 해양과 같은 개활지역에서 모바일 센서 네트워크에서 사용하는 전력량을 감소시킬 수 있는 시스템을 제안한다. 무선 센서 네트워크에서 데이터 전송 전력 소모는 거리의 제곱에 비례하다는 특징이 있다. 따라서 배터리로 동작하는 모바일 센서의 위치가 센서 데이터를 수집하는 싱크 노드와 멀리 떨어져 있을 경우, 데이터를 전송하는데 요구되는 전력 사용량이 높아지게 되어 센서의 동작 시간이 짧아지는 문제가 발생한다. 이에 따라 본 논문에서는 기존 모바일 센서의 전송 가능 거리보다 짧은 전송 거리를 설정하여 센서가 해당 거리 이내에 존재할 때만 데이터를 보내게 함으로써 필요한 전력량을 감소시키는 시스템에 대하여 제안하였다. 뿐만 아니라, 싱크노드에서는 압축 센싱을 이용하여 센서로부터 수집한 데이터를 더 적은 전송 횟수로 게이트웨이에 전송함으로써 전체 네트워크의 에너지 효율을 증가시켰다. 본 논문에서 제안한 시스템은 라즈베리 파이와 아두이노를 이용하여 실제로 구현하였으며, 싱크노드로부터 적은 데이터를 수신하여도 게이트웨이에서 원 데이터와 매우 근사적으로 복호가 가능함을 실험을 통하여 확인하였고 실제 실험 환경에서 제안된 시스템의 성능을 이론적으로 검증하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1599-1610
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• 2019

Intelligent services have expanded as Internet of Things (IoT) technology has evolved and new requirements emerge to accommodate various services. One new requirement is transmitting data over long distances with low-power. Researchers have developed low power wide area (LPWA) network technology to satisfy the requirement; this can improve IoT network infrastructure and increase the range of services. However, network coverage expansion causes several problems. The traffic load is concentrated at a specific gateway, which causes network congestion and leads to decreased transmission efficiency. Therefore, the approach proposed in this paper attempts to recognize and then avoid congestion through gateway channel hopping. The LPWA network employs multiple channels, so wireless channel hopping is available in a gateway. Devices that are not delay sensitive wait for the gateway to reappear on their wireless channel; delay sensitive devices change the wireless channel along the hopping gateway. Thus, the traffic load and congestion in each wireless channel can be reduced improving transmission efficiency. The proposed approach's performance is evaluated by computer simulation and verified in terms of transmission efficiency.

• 한국항행학회논문지
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• 제28권2호
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• pp.250-253
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• 2024

This paper proposes a low-power waveform for a long-range air-to-air data link. In the case of an air-to-air data link, data communication is performed in the air and high Doppler shift may occur depending on the flight speed, so a waveform based on the non-coherent method is suitable. In addition, since it is mounted on an aircraft, it must have low power characteristics. This paper proposes a waveform that combines a modulation technique based on frequency modulation and pulse position modulation that can turn on/off the transmission signal. As a result of the performance analysis, it was shown that the performance was suitable for air-to-air operation while showing low power characteristics.

• 한국정보통신학회논문지
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• 제12권9호
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• pp.1689-1695
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• 2008

저전력 무선 통신의 발전과 다기능, 저가의 스마트 센서는 원격에서 상태정보를 감지할 수 있는 센서네트워크의 실현을 가능하게 하였다. 센서 노드는 소형 배터리를 사용해 에너지를 공급받는데 일반적으로 배터리 교환이 용이하지 않은 위치에 설치되기 때문에 센서 노드의 평균 소모 전력을 최소화할 필요가 있다. 알려진 바에 따르면 센서 노드의 전체 소모 전력의 20-60%를 무선 통신에 사용하는 RF 모듈이 차지하고 있다. 본 논문에서는 센싱된 데이터의 송신에 소비되는 에너지를 개선하기 위해 센싱 데이터의 변동 특성에 실시간 적응하여 확률적 계산값이 임의의 랜덤값보다 클 경우 기지국 노드로 전송하는 확률추론 휴리스틱기반 비주기적 전송 방법을 제안한다. 제안하는 전송 방법에서는 확률추론 휴리스틱 알고리즘에 따라 센싱된 데이터와 직전 센싱된 데이터를 평가하여 전송 여부를 결정하며 알고리즘에 필요한 계수값은 알고리즘 검증 데이터의 재현율을 통하여 결정한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.107.2-107
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• 2001

We propose portable equipment that monitors a current and potential on high-potential power transmission lines. In the equipment, a current and voltage sensor are attached to a hollow insulator that supports a power transmission line: A current on a power line is detected by an air-core solenoidal coil clamped to the line and the detected current signal is transmitted to the ground station by using optical data link, A potential on a power transmission line is detected by a high resistance element, zinc oxide (ZnO) that acts as a potential divider between the power line and the ground. The equipment does not require high potential insulators and magnetic cores which. This leads to the following advantages of the equipment: (a) It is easily installed owing to its small size and its simple structure; (b) It operates in low ...

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1678-1680
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• 1998

The purpose of this study is to obtain optimum arrangement of phase conductors in minimizing magnetic field from overhead transmission lines. Data of the transmission lines rated 345 kV of the KEPCO(Korea Electric Power Company)'s system were used. For a three phase-double circuit transmission line, low-reactance arrangement is optimum in minimizing magnetic fields. For a three phase-four circuit, optimum phase arrangement is a-b-c-b-a-c(lower two circuits, clockwise)/b-c-a-c-a-b(upper two circuits, clockwise).

• Journal of Information Technology Applications and Management
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• 제28권6호
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• pp.87-95
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• 2021

Recently interest for air pollution is gradually increasing. However, according to the environmental assessment of air quality, the level of air pollution in the nation is quite serious, and air pollutants measuring facilities are also not enough. In this paper, a secure air pollutants sensor system based low power wireless communication is designed and implemented. The proposed system is composed of three parts: air pollutants measuring sensors module, LoRa-based data transmission module, and monitoring module. In the air pollutants measuring module, the MSP430 board with six big air pollutants measuring sensors are used. The air pollutants sensing data is transmitted to the control server in the monitoring system using LoRa transmission module. The received sensing data is stored in the database of the monitoring system, and visualized in real-time on the map of the sensor locations. The implemented air pollutant sensor system can be used for measuring the level of air quality conveniently in our daily lives.

• 한국컴퓨터정보학회논문지
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• 제21권1호
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• pp.79-84
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• 2016

In this paper, we propose reliable message transmission scheme based on CoAP, considering the constrained feature of IoT device, such as low power, the limited memory size and low computing capacity. Recently, the various kinds of application protocol has been studied to support IoT environments. In particular, CoAP protocol was developed as application protocol for IoT at the IETF core WG. However, because CoAP protocol is deigned to be used in constrained node, this protocol uses UDP at transport layer. Thus, data loss may occur frequently in network congestion environments. The proposed scheme, in this paper, is to overcome the problem of frequent data loss with low overhead. Also it includes the function which is to minimize the data loss in sleep mode of IoT device.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권2호
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• pp.194-201
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• 2015

A frequency modulated ultra-wideband (FM-UWB) transmitter with a high-robust relaxation oscillator for subcarrier generation and a dual-path Ring VCO for RF FM is proposed, featuring low power and low complexity. A prototype 3.65-4.25 GHz FM-UWB transceiver employing the presented transmitter is fabricated in $0.18{\mu}m$ CMOS for short-range wireless data transmission. Experimental results show a bit error rate (BER) of $10^{-6}$ at a data rate of 12.5 kb/s with a communication distance of 60 cm is achieved and the power dissipation of 4.3 mW for the proposed transmitter is observed from a 1.8 V supply.