• 센서학회지
• /
• 제31권1호
• /
• pp.16-23
• /
• 2022

Cardiac disease is the most common cause of death worldwide. Therefore, detection and classification of electrocardiogram (ECG) signals are crucial to extend life expectancy. In this study, we aimed to implement an artificial intelligence signal recognition system in field programmable gate array (FPGA), which can recognize patterns of bio-signals such as ECG in edge devices that require batteries. Despite the increment in classification accuracy, deep learning models require exorbitant computational resources and power, which makes the mapping of deep neural networks slow and implementation on wearable devices challenging. To overcome these limitations, spiking neural networks (SNNs) have been applied. SNNs are biologically inspired, event-driven neural networks that compute and transfer information using discrete spikes, which require fewer operations and less complex hardware resources. Thus, they are more energy-efficient compared to other artificial neural networks algorithms.

• 한국산학기술학회논문지
• /
• 제21권4호
• /
• pp.356-361
• /
• 2020

소형의 다리형 주행 로봇은 몸체의 크기 대비 바퀴주행보다 높은 장애물을 극복할 수 있다는 장점이 있다. 이러한 이점을 활용하여 다양한 형태의 다리 주행 소형 로봇이 개발되었다. 본 논문에서는 기존의 단면 주행을 넘어 양면 주행이 가능한 12족 생체모사 크롤링 로봇을 제안한다. 주행 로봇은 험지 주행 시에 전복되거나 자세가 흐트러지는 경우가 자주 발생한다. 12족 양면 주행로봇은 전복이 되어도 지체 없이 곧바로 주행이 계속 가능하다. 양면 주행을 위한 핵심 메커니즘은 구동부를 공유하는 것이다. 몸체부의 중간에 위치한 힘 전달 구조가 위와 아래에 위치한 모든 다리로 움직임을 전달한다. 이와 같이, 유사한 기능을 수행하는 구조물을 통합하여 구조의 간소화와 경량화를 달성하였다. 또한, 무게를 줄이기 위하여 종이 기반의 복합재를 사용하여 32g의 경량 설계를 수행하였다. 로봇의 성능을 평가하기 위해, 윗면과 아랫면 모두에 대해 주행 테스트를 실시하였다. 그 결과 윗면으로 주행 시 0.52m/s, 아랫면으로 주행 시 0.42m/s의 속력을 보여주어, 양면 모두 성공적인 주행이 가능함을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제4권6호
• /
• pp.1042-1062
• /
• 2010

Cooperative spectrum sensing (CSS) is an effective technology for alleviating the unreliability of local spectrum sensing due to fading/shadowing effects. Unlike most existing solutions, this paper considers the use of CSS technology in decentralized networks where a fusion center is not available. In such a decentralized network, some attackers may sneak into the ranks of cooperative users. On the basis of recent advances in bio-inspired consensus algorithms, an attack-proof, decentralized CSS scheme is proposed in which all secondary users can maintain cooperative sensing by exchanging information locally instead of requiring centralized control or data fusion. Users no longer need any prior knowledge of the network. To counter three potential categories of spectrum sensing data falsification (SSDF) attacks, some anti-attack strategies are applied to the iterative process of information exchange. This enables most authentic users to exclude potentially malicious users from their neighborhood. As represented by simulation results, the proposed scheme can generally ensure that most authentic users reach a consensus within the given number of iterations, and it also demonstrates much better robustness against different SSDF attacks than several existing schemes.

• ETRI Journal
• /
• 제35권3호
• /
• pp.414-424
• /
• 2013

We consider a new load balancing routing for delay-guaranteed services in the network in which the traffic is dynamic and network topologies frequently change. For such an ever-changing network, we propose a new online load balancing routing called AntLBR, which exploits the ant colony optimization method. Generally, to achieve load balancing, researchers have tried to calculate the traffic split ratio by solving a complicated linear programming (LP) problem under the static network environment. In contrast, the proposed AntLBR does not make any attempt to solve this complicated LP problem. So as to achieve load balancing, AntLBR simply forwards incoming flows by referring to the amount of pheromone trails. Simulation results indicate that the AntLBR algorithm achieves a more load-balanced network under the changing network environment than techniques used in previous research while guaranteeing the requirements of delay-guaranteed services.

• Smart Structures and Systems
• /
• 제8권1호
• /
• pp.107-117
• /
• 2011

Biological sensory systems continuously monitor and analyze changes in real-world environments that are relevant to an animal's specific behavioral needs and goals. Understanding the sensory mechanisms and information processing principles that biological systems utilize for efficient sensory data acquisition may provide useful guidance for the design of smart-sensing systems in engineering applications. Weakly electric fish, which use self-generated electrical energy to actively sense their environment, provide an excellent model system for studying biological principles of sensory data acquisition. The electrosensory system enables these fish to hunt and navigate at night without the use of visual cues. To achieve reliable, real-time task performance, the electrosensory system implements a number of smart sensing strategies, including efficient stimulus encoding, multi-scale virtual sensor arrays, task-dependent filtering and online subtraction of sensory expectation.

• 로봇학회논문지
• /
• 제13권2호
• /
• pp.97-102
• /
• 2018

A small and lightweight crawling robots have been actively studied thanks to their outstanding mobility and maneuverability. Those robots can navigate into more confined spaces that larger robots are unable to reach or enter such as debris and caves. In this paper, we propose a milli-scale hexapedal robot based on planar linkage design. To make this possible, two necessary conditions for successful crawling are satisfied: thrust force from the ground and aerial phase while running. These conditions are achieved through a newly developed leg design. The robot has a pair of legs and each leg has three feet. Those feet alternatively moves based on 1DOF planar linkage. This linkage is installed at each side of the robot and finally the robot shows the alternating gait and aerial phase during running. As a result, the robot runs with the crawling speed of 0.9 m/s.

• 한국정밀공학회지
• /
• 제30권10호
• /
• pp.1023-1029
• /
• 2013

Water running animals such as basilisk lizards have an advantage of high-speed movement and high power efficiency on water; so researchers in robotic fields have been interested in the water running locomotion. This paper presents prototype-design and experimental study on the fourand six-legged water running robot. Based on the previously proposed quadruped water running robot, we assemble a hexapedal water running robot. The legs of the water running robot are designed based on four-bar parallel link for repeated motion along to pre-defined path. Stability performance of the quadruped and hexapedal water running robot are investigated by experiments on rolling criterion. As a result, hexapedal robot performs better stability than quadruped robot. Based on the hexapedal robot design, we are planning to optimize the position of legs and operating frequency.

• Journal of information and communication convergence engineering
• /
• 제9권5호
• /
• pp.615-618
• /
• 2011

Living cells generate the cell cycle or apoptosis, depending on the course will be repeated. If an error occurs during this period of life in order to maintain the cells in the peripheral cells find the error portion. These cellular functions were applied to the system to simulate the circuit. Circuit implementation of the present study was constructed the redundant structure in order to found the error quickly. Self-repairing of digital systems as an advanced form of fault-tolerance has been increasingly receiving attention according as digital systems have been more and more complex and speed-up especially for urgent systems or those working on extreme environments such as deep sea and outer space. Simulating the process of cell differentiation algorithm was confirmed by the FPGA on the counter circuit. If an error occurs on the circuit where the error was quickly locate and repair. In this paper, we propose a novel self-repair architecture for fast and robust fault-recovery that can easily apply to real, complex digital systems. These Self-Repairing Algorithms make it possible for the application digital systems to be alive even though in very noisy and extreme environments.

• Smart Structures and Systems
• /
• 제17권3호
• /
• pp.523-539
• /
• 2016

The ambient vibration measurement is an output-data-only dynamic testing where natural excitations are represented, for instance, by winds and typhoons. The modal identification involving output-only measurements requires the use of specific modal identification techniques. This paper presents the application of a reliable method (the Stochastic Subspace Identification - SSI) implemented in a general purpose software. As a criterion toward the robustness of identified modes, a bio-inspired optimization algorithm, with a highly nonlinear objective function, is introduced in order to find the optimal deployment of a reduced number of sensors across a large civil engineering structure for the validation of its modal identification. The Ting Kau Bridge (TKB), one of the longest cable-stayed bridges situated in Hong Kong, is chosen as a case study. The results show that the proposed method catches eigenvalues and eigenvectors even for a reduced number of sensors, without any significant loss of accuracy.

• Smart Structures and Systems
• /
• 제8권1호
• /
• pp.93-105
• /
• 2011

This paper presents a flexible low-profile antenna sensor for fatigue crack detection and monitoring. The sensor was inspired by the sense of pain in bio-systems as a protection mechanism. Because the antenna sensor does not need wiring for power supply or data transmission, it is an ideal candidate as sensing elements for the implementation of engineering sensor skins with a dense sensor distribution. Based on the principle of microstrip patch antenna, the antenna sensor is essentially an electromagnetic cavity that radiates at certain resonant frequencies. By implementing a metallic structure as the ground plane of the antenna sensor, crack development in the metallic structure due to fatigue loading can be detected from the resonant frequency shift of the antenna sensor. A monostatic microwave radar system was developed to interrogate the antenna sensor remotely. Fabrication and characterization of the antenna sensor for crack monitoring as well as the implementation of the remote interrogation system are presented.