• IEMEK Journal of Embedded Systems and Applications
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• v.16 no.1
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• pp.29-34
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• 2021

We developed a pet care robot that can be controlled outdoors. Through the smartphone application, the pet owners can watch the situation in the house and manipulate the robot to make their pet happy. The video data in the house is transmitted to the application through the webcam installed at the house. The robot can not only perform user's command but also do six basic macro action. The obstacle avoidance function using the current sensor can be activated if the user want to use. When the robot hits to something, it moves back and rotates by arbitrary angle, and then moves forward.

• Fire Science and Engineering
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• v.26 no.1
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• pp.74-79
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• 2012

This study is described for development of the stand-alone smoke and heat detector (SASHD) according to the revised in 2011 type approval and performance inspection code for detector. The main improvement of the revised regulation is source. CMOS microcontroller with nano watt technology is use for development of the workable SASHD over 10 years. The low-power SASHD is developed by using the power-saving sleep mode of microcontroller, by making the low-power source voltage checker, heat detector and smoke detector. The stand-alone detector is developed by smoke and heat detector type for reduce false fire alarm. User can choose type of work between the heat detection mode and smoke & heat detection mode. The SASHD can communicate with each them using RS-485 communication supported from microcontroller. So, this study can develop the SASHD that is able to alarm more wide area when fire occurs and reduce a flash fire alarm.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.8
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• pp.10-15
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• 2012

This letter proposes a low-leakage SRAM using power-gating and voltage-level control. The power-gating scheme significantly reduces leakage power by shutting off the power supply to blank memory cell blocks. The voltage-level control scheme saves leakage power by raising the ground line voltage of SRAM cells and word line decoders in data-stored memory cell blocks. A $4K{\times}8bit$ SRAM chip was fabricated using a 1.2V $0.13{\mu}m$ CMOS process. The leakage powers are $1.23{\sim}9.87{\mu}W$ and $1.23{\sim}3.01{\mu}W$ for 0~100% memory usage in active and sleep modes, respectively. During the sleep mode, the proposed SRAM consumes 12.5~30.5% leakage power compared to the conventional SRAM.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.177-182
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• 2014

In this paper, we propose an energy efficient sink node based MAC protocol for Wireless Sensor Networks (WSNs). The proposed sink node-based MAC (SB-MAC) protocol uses a RB(rapid beacon) frame to save sender's energy consumption and to reduce transmission delay. The RB frame is a modified IEEE 802.15.4 beacon frame. The RB frame contains the length of the sender nodes data. Using this information other nodes except sender and receiver nodes can be stay sleep mode long time to reduce energy consumption. Results have shown that the SB-MAC protocol outperformed other protocols like X-MAC and RI-MAC in terms of packet delivery delay and energy consumption. The SB-MAC protocol is especially energy efficient for the networks with one sink node and many senders.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.1-8
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• 2008

Recently, there is developing various ubiquitous application services using sensor networks based on TinyOS represented the operating system of sensor node. These sensor networks perform the collection and the transmission of sensing data from sensor node to get the context information. In this paper, we proposes the sensor node control algorithm which converts a sensor node to sleep, active, power off mode according to monitoring result of the voltage state of sensor node. Also, we designs and implement the sensor control module on server, sink, sensor node of sensor networks using this algorithm. It designs a sensor voltage control module of sensor node, data receive and display module of USN server using a java language and TinyOS. And, it checks the voltage state of sensor node, and it changes one of the sleep or power off modes in case of high voltage loss. Accordingly, we effectively use the power of sensor nodes as changing control modes of sensor nodes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.6
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• pp.89-95
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• 2008

In this paper, we designed a low power face detection hardware and analysed its power consumption. The face detection hardware was fabricated using Samsung 0.18um CMOS technology and it can detect multiple face locations from a 2-D image. The hardware is composed of 6 functional modules and 11 internal memories. We introduced two operating modes(SLEEP and ACTIVE) to save power and a clock gating technique was used at two different levels: modules and registers. In additional, we divided an internal memory into several pieces to reduce the energy consumed when accessing memories, and fully utilized low power design option provided in Synopsis Design Compiler. As a result, we could obtain 68% power reduction in ACTIVE mode compared to the original design in which none of the above low power techniques were used.

• Journal of the Korea Society of Computer and Information
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• v.16 no.4
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• pp.119-126
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• 2011

When ZigBee network supports beacon transmission mechanism, ZigBee devices have the restriction of the transmission range from the coordinator. On the contrary, when it does not support beacon transmission, it is not easy to save the energy through turning into sleep mode. This paper proposes active slot allocation method that allocates a transmission time and does not use the beacon transmission mechanism. It is based on the ZigBee's distributed address assignment mechanism and supports the scalability. This paper explains the active slot structure and the allocation order and describes the operation of ZigBee devices. We verify the proposed mechanism through the simulation and show the performance evaluation. It can be useful on the industrial automation and the environmental surveillance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1569-1580
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• 2016

For the 2.4 GHz active RFID to be successful in the market, one of the requirements is the increased battery life. However, currently we do not have any accurate power consumption estimation method. In this study we develop a simulation model, which can be used to estimate power consumption of tag accurately. Six different simulation models are proposed depending on collision algorithm and query command method. To improve estimation accuracy, we classify tag operating modes as the wake-up receive, UHF receive, sleep timer, tag response, and sleep modes. Power consumption and operating time are identified according to the tag operating mode. Query command for simplifying collection and ack command procedure and newly developed collision control algorithm are used in the simulation. Other performance measures such as throughput, recognition time for multi-tags, tag recognition rate including power consumption are compared with those from the current standard ISO/IEC 18000-7.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.153-164
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• 2010

In this paper, we propose a multi-channel MAC protocol to improve the channel efficiency and network performance in wireless ad hoc networks. There are two main problems encountered in designing multi-channel MAC protocols. The first problem is the rendezvous problem and the second is multi-channel hidden node problem. In order to solve these problems, most of previous researches that have considered multi-channel MAC protocols use a common control channel to exchange control packets. However, they have a bottleneck problem at common control channel as increasing the number of data channels. The proposed MAC protocol solves the multi-channel hidden node problem using a TDMA scheme and increases the network throughput because transmitting and receiving data at the same time is possible. Also, since there is no common control channel, the network does not suffer from the common control channel saturation problem. Moreover, it achieves energy savings by allowing nodes that are not involved in communication to go into sleep mode. Simulation results show that the proposed MAC protocol improves the network throughput and channel efficiency and provides energy savings.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.99-103
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• 2006

In this paper, we focus on the problem of designing an energy efficient MAC protocol for wireless sensor networks and analyze S(Sensor)-MAC and T(Time-out)-MAC. S-MAC is based on the concept of the 'listen/sleep mode cycle'. This applies message passing to reduce contention latency for sensor-network applications that require store-and-forward processing as data moves through the network. However unlike the S-MAC, where the duration of the cycle is fixed, T-MAC introduces an adaptive duty cycle in a novel way: by dynamical ending the active part of it. This reduces the amount of energy wasted on idle listening, in which nodes wait for potentially incoming messages while still maintaining a reasonable throughput. In this paper we discuss the design of these two Protocols. We analyze them from the aspect of latency, throughput, and power savings when using the OMNeT++ simulator in various environments.