• Journal of IKEEE
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• v.25 no.4
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• pp.584-590
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• 2021

This paper proposes a removal method of signal interference between ultrasound sensors where ghost signals due to interference are excluded and correct signal is recognized in distance mensurement using ultrasound sensors. The proposed method detects and excludes ghost signals when previous measured distance is compared to current measured distance and the distance difference exceeds a threshold. The threshold is fixed in conventional methods, so ghost signals cannot be correctly excluded when ultrasound sensor or target object move rapidly. On the contrary, to improve accuracy, the threshold is not fixed in the proposed method, and the threshold is adpatively determined based on the relative velocity when ultrasound sensor or target object move. Experiments of distance measurement with ultrasound signal interference are carried out where multiple ultrasound sensors of same type are exploited with maximum interference, and the results show that the proposed method efficiently exclude ghost signals.

• Journal of Intelligence and Information Systems
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• v.15 no.1
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• pp.51-64
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• 2009

A location tracking sensor such as GPS, INS, Radar, and optical equipments is used in tracking Maneuvering Targets with a multi-sensor, and such systems are used to track, detect, and control UAV, guided missile, and spaceship. Until now, Most of the studies related to tracking Maneuvering Targets are on fusing multiple Radars, or adding a supplementary sensor to INS and GPS. However, A study is required to change the degree of application in fusions since the system property and error property are different from sensors. In this paper, we perform the error analysis of the sensor properties by adding a ground radar to GPS and INS for improving the tracking performance by multi-sensor fusion, and suggest the tracking algorithm that improves the precision and stability by changing the sensor probability of each sensor according to the error. For evaluation, we extract the altitude values in a simulation for the trajectory of UAV and apply the suggested algorithm to carry out the performance analysis. In this study, we change the weight of the evaluated values according to the degree of error between the navigation information of each sensor to improve the precision of navigation information, and made it possible to have a strong tracking which is not affected by external purposed environmental change and disturbance.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.351-359
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• 2004

Velocity-type repisratory air flow transducer measures dynamic pressure converted from air velocity based on the we1l-known Bernoulli's principle. It requires multiple velocity sampling holes on the flow plane. Measurement error theoretica1ly estimated by computer simulation was demonstrated to significantly reduce by unequally locating the velocity sampling holes. The flow plane was divided into multiple equi-area rings and the sampling holes were located on the circles also equally dividing each ring's area, which decreased measurement error down to 1/5 of the simple equi-radius ring division method. Also, less than 1 ％ relative error was estimated with 4 or more sampling holes. The present technique was less sensitive by <1/2 to the velocity profile change compared to the euqi-radius sampling. Therefore, the present unequal distance velocity sampling technique should be of great use to design the structure of the velocity-type respiratory air flow transducer.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.397-399
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• 2005

무선 센서노드를 활용한 다양한 네트워크 설계 기술은 실생활의 각종 정보 수집에서부터 환경 모니터링까지 폭넓은 활용범위를 바탕으로 저전력 노드 설계 기술, 노드간 라우팅 프로토콜, 초소형 운영체제 및 미들웨어기술 등 관련 연구가 활발히 수행되고 있으며, 실내 센서네트워크에 분포된 노드의 절대위치를 측정하는 위치인식 시스템은 노드의 이동성, 다수성 그리고 환경의 제약성으로 인해 이를 보완할 시스템이 요구되고 있다. 이에 본 논문에서는 고정 센서노드의 배치밀도에 따라 위치정보를 선별적으로 처리하는 위치데이터 처리기와 다중 위치데이터의 발생을 원천적으로 차단하는 노드간 라우팅 기법을 통해, 센서노드의 이동성과 다중성을 효과적으로 보완하는 실내 이동객체 위치인식 시스템을 설계하고 서비스 구현을 위한 센서네트워크 플랫폼을 제안한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.8
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• pp.671-677
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• 2017

A new INS/Vision integrated navigation system by using multi-vision sensors is addressed in this paper. When the total number of landmark measured by the vision sensor is smaller than the allowable number, there is possibility that the navigation filter can diverge. To prevent this problem, multi-vision concept is applied to expend the field of view so that reliable number of landmarks are always guaranteed. In this work, the orientation of camera installed are 0, 120, and -120degree with respect to the body frame to improve the observability. Finally, the proposed technique is verified by using numerical simulation.

• Journal of Convergence Society for SMB
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• v.4 no.4
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• pp.1-6
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• 2014

A wireless sensor network is being actively researched around the world that are connected to the mesh are a plurality of sensor nodes in a wireless manner that span different regions of the techniques. However, wireless communications use the limitation of resources, so it is very weak due to the properties of the network itself secure in comparison to the normal network. Wireless sensor network is divided into tapped-based attacks, forgery based attacks, denial of service attacks based largely by securities laws must defend against various attacks such as insertion of the wrong information being sent eavesdropping or modification of information, which is usually sensor network applications need to do. The countermeasure of sensor network attack is described in this research, and it will contribute to establish a secure sensor network communication.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.91-96
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• 2014

Since the sensors of Internet of Things (IOT) collect various data, the lifetime of sensor network is very important and the data should be aggregated efficiently. The contiguous collection by the certain sensors occurs an excessive battery consumption and successive transmission of same value of data should be avoided. To solve these things, we propose an weight-based cluster head replacement method that divides whole network into several grids and cluster head is selected by remaining energy, density of alive sensors and location of sensor. The aim of algorithm maximizes the lifetime of network. Our simulation results shows that the proposed method is very simple as well as balances energy consumption.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.1116-1119
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• 2008

무선 센서 네트워크는 주변 정보를 감지할 수 있는 다수의 센서들로 구성된 네트워크로 다양한 분야에서 활용되고 있다. 과거에는 무선 센서 네트워크 환경에서 각 센서들 간의 비밀통신이 중요한 이슈였으며, 특히 이를 위한 키 관리 기법들이 주요 연구방향이었다. 하지만 잘 분배되고 관리된 키라 할지라도, 공격자에 의해 특정한 센서 노드(node)가 수집되면, 노출된 노드(compromised node)가 가지고 있는 키가 공격자에게 들어나게 된다. 노출된 공유키(shared key)를 통해 노출되지 않은 정상 노드(non-compromised node) 사이의 대칭키(pairwise key)를 얻을 수 있으며 결국 공격자는 네트워크에 심각한 영향을 줄 수 있는 메시지 삽입 및 수정 공격을 감행할 수 있다. 본 논문에서는 이와 같은 공격을 탐지하고 오용된 키(misused key)를 폐기하기 위한 방법으로 DAC(detection at cluster header) 기법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.777-785
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• 2009

In recent wireless sensor networks, stationary nodes and mobile nodes co-exist to provide a diverse service. However, because there are multiple mobile nodes located in the wireless sensor network, there is a potential for the instability due to the frequent network reconfiguration and the traffic caused by densely concentration of mobile nodes while mobile nodes are switching locations. In order to solve this problem, we propose the pumping node architecture to solve this traffic congestion problem due to the crowds of mobile nodes. The pumping node can be reduced heavy traffic by pumping through the backbone network caused by the densely concentration of the mobile nodes. As a result, the architecture reduces the traffic in the sensor network with high reliability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1921-1927
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• 2009

In this paper, a point-to-multipoint wireless communication system based on Bluetooth specifications, which is possibly applied to very large vessels, is implemented and analyzed. Here, a communication network is composed of a slave Bluetooth module connected to the task computer and multiple master Bluetooth modules equipped with a sensor. And exploiting the point-to-multipoint data communication among the Bluetooth modules, a surveillance system that recognizes and controls a variety of emergency situations happened on a large vessel is implemented. It is, therefore, considered that the wireless communication system implemented in this paper is possibly exploited a basic technology for the digital shipbuilding of the next generation.