• Journal of Institute of Control, Robotics and Systems
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• v.12 no.4
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• pp.389-394
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• 2006

Inaccurate localization exposes a robot to many dangerous conditions. It could make a robot be moved to wrong direction or damaged by collision with surrounding obstacles. There are numerous approaches to self-localization, and there are different modalities as well (vision, laser range finders, ultrasonic sonars). Since sensor information is generally uncertain and contains noise, there are many researches to reduce the noise. But, the correctness is limited because most researches are based on statistical approach. The goal of our research is to measure more exact robot location by matching between built VRML 3D model and real vision image. To determine the position of mobile robot, landmark-localization technique has been applied. Landmarks are any detectable structure in the physical environment. Some use vertical lines, others use specially designed markers, In this paper, specially designed markers are used as landmarks. Given known focal length and a single image of three landmarks it is possible to compute the angular separation between the lines of sight of the landmarks. The image-processing and neural network pattern matching techniques are employed to recognize landmarks placed in a robot working environment. After self-localization, the 2D scene of the vision is overlaid with the VRML scene.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.2
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• pp.105-113
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• 2007

Accurate and low-cost sensor localization is a critical requirement for the deployment of wireless sensor networks in a wide variety of application. Sensor position is used for its data to be meaningful and for energy efficient data routing algorithm especially geographic routing. The previous works for sensor localization utilize global positioning system(GPS) or estimate unknown-location nodes position with help of some small reference nodes which know their position previously. However, the traditional localization techniques are not well suited in the senor network for the cost of sensors is too high. In this paper, we propose the sensor localization method with a mobile robot, which knows its position, moves through the sensing field along pre-scheduled path and gives position information to the unknown-location nodes through wireless channel to estimate their position. We suggest using the sensor position estimation method and an efficient mobility path model. To validate our method, we carried out a computer simulation, and observed that our technique achieved sensor localization more accurately and efficiently than the conventional one.

• Composites Research
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• v.31 no.4
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• pp.145-150
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• 2018

Various structural health monitoring (SHM) systems have been suggested for aerospace industry in order to increase its life-cycle and economic efficiency. In the case of aircraft structure madden with metal, a major concern was hot spots, such as notches, bolts holes, and where corrosion or stress concentration occurs due to moisture or salinity. However, with the increasing use of composites in the aerospace industry, further advanced SHM systems have been being required to be applied to composite structures, which have much complex damage mechanism. In this paper, a method of acoustic emission localization for composite structures using Q-switched laser and multiple Amplifier-integrated PZTs have been proposed. The presented technique aims at localization of the AE with an error in distance of less than 10 mm. Acoustic emission simulation and the localization attempt were conducted in the composite structure to validate the suggested method. Localization results, which are coordinates of detected regions, grid plots and color intensity map have been presented together to show reliability of the method.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.11
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• pp.1092-1098
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• 2007

A mobile robot localization problem can be classified into following three sub-problems as an observation likelihood model, a motion model and a filtering technique. So far, we have developed the range sensor based, integrated localization scheme, which can be used in human-coexisting real environment such as a science museum and office buildings. From those experiences, we found out that there are several significant issues to be solved. In this paper, we focus on three key issues, and then illustrate our solutions to the presented problems. Three issues are listed as follows: (1) Investigation of design requirements of a desirable observation likelihood model, and performance analysis of our design (2) Performance evaluation of the localization result by computing the matching error (3) The semi-global localization scheme to deal with localization failure due to abrupt wheel slippage In this paper, we show the significance of each concept, developed solutions and the experimental results. Experiments were carried out in a typical modern building environment, and the results clearly show that the proposed solutions are useful to develop practical and integrated localization schemes.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.6
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• pp.641-648
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• 2009

Currently several kinds of sensor localization methods have been developed for terrestrial wireless sensor networks. This study, in order to extend the field to underwater environments, a localization technique is studied for UWSNs (Underwater Wireless Sensor Networks). In underwater environments, RF (Radio Frequency) signal is not suitable for underwater usage because of extremely limited propagation. Because of that reason UWSNs should be constituted with acoustic modems. But, to realize underwater application, we can borrow many design principles from ongoing research for terrestrial environments. So, in this paper we introduce the modified localization algorithm using ToA method which is based on the terrestrial research. First of all, we study the localization techniques for terrestrial environments where we investigate possible methods to underwater environment. And then the appropriate algorithm is presented in the underwater usage. Finally the proposed underwater based localization algorithm is evaluated by using computer.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.5
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• pp.490-495
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• 2015

As flying robots are becoming popular, there are increased needs to use themforsuch purposes as parcel delivery, serving in restaurants, and stage performances. To control flying robots such as quad copters, localization is essential. In order to properly position flying robots, many techniques are in development, including IR (infra-red)-based systemswhich catch markers on a flying robot in order that it can position itself. However, this technique demonstrates only short coverage. Furthermore, localization from inertial sensors diverges as time passes. For this reason, this paper suggests a TWR (two-way ranging) based positioning technique. Despite the weaknesses in currently available TWR system, this paper suggests a self-positioning and outlier detection technique in order to provide reliable position information with a faster update rate. The self-positioning system sends a shorter message which reduces wireless traffic. By detecting and removing outlier measurements, a positioning result with better accuracy is acquired. Finally, this paper shows that the suggesting system detects outlierssequentially from less than half the number of anchors in localization system according to the degree of outlier in measurement and the noise level. By performing an outlier algorithm, better positioning accuracy is acquired as shown in the experimental result.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3185-3190
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• 2016

Background: This study was designed to compare radioguided versus routine wire localization of nonpalpable non-malignant breast lesions in terms of efficacy for complete excision, ease of use, time saving, and cosmetic outcome. Materials and Methods: Patients with non-palpable breast masses and non-malignant core biopsy results who were candidates for complete surgical lumpectomy were enrolled and randomly assigned to radioguided or wire localization groups. Radiologic, surgical, and pathologic data were collected and analyzed to determine the difficulty and duration of each procedure, ease of use, accuracy, and cosmetic outcomes. Results: This prospective randomized study included 60 patients, randomly divided into wire guided localization (WGL) or radioguided occult lesion localization (ROLL) groups. The mean duration of localization under ultrasound guidance was shorter in the ROLL group (14.4 min) than in the WGL group (16.5 min) (p<0.001). The ROLL method was significantly easier for radiologists (p=0.0001). The mean duration of the surgical procedure was 22.6 min (${\pm}10.3min$) for ROLL and 23.6 min (${\pm}9.6min$) for WGL (p=0.6), a non-significant difference. Radiography of the surgical specimens showed 100% lesion excision with clear margins, as proved by pathologic examination, with both techniques. The surgical specimens were slightly heavier in the ROLL group, but the difference was not significant (p=0.06). Conclusions: The ROLL technique provides effective, fast, and simple localization and excision of non-palpable non-malignant breast lesions.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.111-118
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• 2010

The proposed algorithm to be explained in this paper is the localization technique using directional antenna. Here, it is assumed that anchor node has the ability to transfer the azimuth of each sector using GPS modules, sector antenna, and the digital compass. In the conventional sensor network, the majority of localization algorithms were capable of estimating the position information of the sensor node by knowing at least 3 position values of anchor nodes. However, this paper has proposed localization algorithm that estimates the position of nodes to continuously move with sensor nodes and traveling nodes. The proposed localization mechanisms have been simulated in the Matlab. The simulation results show that our scheme performed better than other mechanisms (e.g. MCL, DV-distance).

• KIEE International Transaction on Systems and Control
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• v.2D no.2
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• pp.53-58
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• 2002

In this paper, various aspects in magnetoencephalography (MEG) source localization are studied. To minimize the errors in experimental data, an approximation technique using a polynomial function is proposed. The simulation shows that the proposed technique yields more accurate results. To improve the convergence characteristics in the optimization algorithm, a hybrid algorithm of evolution strategy and sensitivity analysis is applied to the neuromagnetic inverse problem. The effectiveness of the hybrid algorithm is verified by comparison with conventional algorithms. In addition, an artificial neural network (ANN) is applied to find an initial source location quickly and accurately. The simulation indicates that the proposed technique yields more accurate results effectively.

• The Journal of Korea Robotics Society
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• v.12 no.4
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• pp.402-410
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• 2017

Acoustic based localization is essential to operate autonomous robotic systems in underwater environment where the use of sensorial data is limited. This paper proposes a localization method using artificial underwater acoustic sources. The proposed method acquires directional angles of acoustic sources using time difference of arrivals of two hydrophones. For this purpose, a probabilistic approach is used for accurate estimation of the time delay. Then, Gaussian sum filter based SLAM technique is used to localize both acoustic sources and underwater vehicle. It is performed by using bearing of acoustic sources as measurement and inertial sensors as prediction model. The proposed method can handle directional ambiguity of time difference based source localization by generating Gaussian models corresponding to possible locations of both front and back sides. Through these processes, the proposed method can provide reliable localization method for underwater vehicles without any prior information of source locations. The performance of the proposed method is verified by experimental results conducted in a real sea environment.