• Journal of Ubiquitous Convergence Technology
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• 제2권2호
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• pp.78-87
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• 2008

Received signal strength indicator (RSSI) is used as one of the ranging techniques to locate dynamic sensor nodes in wireless sensor network. Before it can be used for position estimation, RSSI values must be converted to distances using path loss model. These distances among sensor nodes are combined using trilateration method to find position. This paper presents an idea which attempts to integrate both path loss model and trilateration as one algorithm without going through RSSI-distance conversion. This means it is not simply formulas combination but a whole new model was developed. Several advantages were found after integration: it is able to reduce processing load, and ensure that all values do not exceed the maximum range of 16-bit signed or unsigned numbers due to antilog operation in path loss model. The results also show that this method is able to reduce estimation error while inaccurate environmental parameters are used for RSSI-distance conversion.

• 제어로봇시스템학회논문지
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• 제18권6호
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• pp.571-578
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• 2012

In the paper, we proposed a ring type structured light image based embedded ranging sensor for a mobile robot. Since the proposed ranging sensor obtains omnidirectional object distance, it is useful for autonomous navigation of a mobile robot. By matching the local omnidirectional distance map with a given global object map, it is possible to get position and heading angle of mobile robot in the global coordinates. Experiments for matching and navigation were carried out to verify the performance of the proposed ranging sensor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.433-435
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• 2007

Geographic wireless sensor networks use position information for Greedy routing. Greedy routing works well in dense network where as in sparse network it may fail and require the use of recovery algorithms. Recovery algorithms help the packet to get out of the communication void. However, these algorithms are generally costlier for resource constrained position based wireless sensor type networks. In the present work, we propose a Void Avoidance Algorithm (VAA); a novel idea based on virtual distance upgrading that allows wireless sensor nodes to remove all stuck nodes by transforming the routing graph and forward packet using greedy routing only without recovery algorithm. In VAA, the stuck node upgrades distance unless it finds next hop node which is closer to the destination than itself. VAA guarantees the packet delivery if there is a topologically valid path exists. NS-2 is used to evaluate the performance and correctness of VAA and compared the performance with GPSR. Simulation results show that our proposed algorithm achieves higher delivery ratio, lower energy consumption and efficient path.

• 센서학회지
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• 제23권3호
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• pp.158-164
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• 2014

In indoor sensor networks equalization algorithms based on the minimization of Euclidean distance (MED) for the distributions of constant modulus error (CME) have yielded superior performance in compensating for signal distortions induced from optical fiber links, wireless-links and for impulsive noise problems. One main drawback of MED-CME algorithms is a heavy computational burden hindering its implementation. In this paper, a recursive gradient estimation for weight updates of the MED-CME algorithm is proposed for reducing the operations $O(N^2)$ of the conventional MED-CME to O(N) at each iteration time for N data-block size. From the simulation results of the proposed recursive method producing exactly the same results as the conventional method, the proposed estimation method can be considered to be a reliable candidate for implementation of efficient receivers in indoor sensor networks.

• 한국컴퓨터정보학회논문지
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• 제20권11호
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• pp.63-68
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• 2015

In this paper, we propose a new energy efficient scheme which can prolong the life of sensor networks, it should be able to reduce the number of sensing. We use the concept of safe zone for manage the appropriate range of properties. We measure the distance between the sensed temperature value and the center of the zone, and calculate the next sensing interval based on this distance. We name our proposed scheme "VIS". To assess the performance of the proposed scheme the actual temperature data was collected using the sensor node. The algorithm was implemented through the programming and was evaluated in a variety of settings. Experimental results show that the proposed algorithm is to significantly reduce the number of sensing in terms of energy efficiency while having the ability to know the state of the sensor nodes periodically. Our VIS algorithm can be useful in applications which will require the ability of control to the temperature within a proper range.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.387-390
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• 1993

The most important technique for an indoor robot navigation is to find out the direction and the distance from the current location to the destination through the information achieved from the sensor. For this purpose, we suggest sensor-based local homing method which compares the destination sensory data with the current location. As for the sensors, we use the CCD camera and the ultrasonic sensor, and recorded entire 360 degree panoramic data. We match the features of the image data, and the distance and the direction of the matched point will be considered as fuzzy numbers. Through a simple fuzzy arithmetic, we infer the geometric relations between the current location and the destination location.

• 한국자동차공학회논문집
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• 제25권3호
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• pp.309-316
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• 2017

In shuttle vans designed to transport children, the recognition of a child's approach and departure is very important. Ultrasonic sensors are generally used for a short distance around a vehicle. Although ultrasonic sensors are cheaper than other ADAS sensors, the number of sensors installed in a van should be optimized. In order to recognize the presence of a child around a shuttle van, this paper proposes the placement of ultrasonic sensors in the van. Considering the turning radius of the van and the distance from each sensor to a child, collision risk is classified as 'safe', 'warning', and 'danger'. The sensor placement and the recognition algorithm are verified in a virtual driving environment.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1993년도 추계학술대회
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• pp.44-47
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• 1993

In this paper, the wall follwing method of a motorized wheelchair is discussed. The wall fellowing problem is characterized by maintaining a constant distance to the wall, which should be possible using a distance measuring sensor only. Ultrasonic sensors are cheap are fairly simple to use in this case. The main problem is the calculation of the distance and orientation of the wheelchair with respect the wall from the sensor data. This is solved by the method that sensor data is obtained from 3 ultrasonic sensors arranged at a same perpendicular pivot. The results show that a new method is very effiecient for a motorized wheelchair.

• 비파괴검사학회지
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• 제10권1호
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• pp.10-17
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• 1990

Recently, object recognition ultrasonic sensor is being used with automatization of industrial machine. Points which characterize the object can be deleted by measuring the propagation time of ultrasonic impulse and azimuth which gives its maximum amplitude, and from these points shape, position and orientation of the object are deduced. A new measuring method is adopted, where the distance to the object is calculated by sound reflection time which is measured from O-cross point of sound wave, and azimuth is measured by angle indicating maximum amplitude. The measuring accuracy of 1.0mm for distance and $0.5-2^{\circ}$ for azimuth have been accomplished. By rotational scanning of sensor the characteristic point of an object can be known and it gives the information of its shape, position and orientation. Experimental results showed that the object of some complicated shape can be recognized, which suggest its applicability to robot.

• 디지털융복합연구
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• 제20권4호
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• pp.513-518
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• 2022

지난 2년간 코로나 19로 인한 사회의 모든 분야가 저발전을 이루고, 많은 피해를 입었다. 특히 사람간의 모임제안, 간격유지로 연구 분야에서 일하고 있는 많은 사람들은 특히 더 아무것도 할 수 없는 상황이었다. UX Design을 통한 코로나 19 사회에서 사람들의 사회적거리두기 방법 분석을 통해 정부거리 지침에 맞는 간격을 유지 할 수 있는 거리유지 장치를 개발하는 것이 본 연구의 목적이다. 거리유지 장치 개발을 위해 초음파거리감지센서와 배터리, 충전방식, 거리표시방식, 등의 UI 디자인에 관한 연구를 통해 LED의 색상의 변화로 거리를 표현한다. 본 연구의 방법은 거리유지 장치의 외형을 3D로 디자인하고 3D 프린터를 통해 프로토타입을 출력하여 초음파거리감지 센서, 네오픽셀모듈, 그리고 아두이노 설치를 통해 장치를 개발하고, 이것을 테스트 하여 코로나 19로부터 사회적거리두기의 실천을 돕는 실제 제품을 개발하는 것이다.