• Steel and Composite Structures
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• v.50 no.6
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• pp.609-625
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• 2024

This paper presents an in-depth analysis of the nonlinear vibration of microbeams, with a particular emphasis on their application in sports monitoring systems. The research utilizes classical beam theory, modified couple stress theory, and von-Kármán nonlinear parameters to explore the behavior of microbeams. These microbeams are characterized by a non-uniform geometry, with materials that continuously change along the beam radius and a thickness that varies along the beam length. The main contribution lies in its exploration of the stability of smart sensors in sports structures, particularly those with non-uniform geometries. The research findings indicate that these non-uniform microbeams, when used in smart systems made of functionally graded temperature-dependent materials, can operate effectively in thermal environments. The smart system developed in this study demonstrates significant potential for use in sports applications, particularly in monitoring and gathering information. The insights gained from this research contribute to the understanding of the performance and optimization of microbeams in sports applications, particularly in the context of non-uniform geometries. This research, therefore, provides a foundation for the development of advanced, reliable, and efficient monitoring systems in sports applications.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.5
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• pp.305-310
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• 2015

We propose a new concept for a depth of interaction (DOI) positron emission tomography (PET) detector based on dual-ended-scintillator (DES) readout for small animal imaging. The detector consists of lutetium yttrium orthosilicate (LYSO) arrays coupled with orthogonal wavelength-shifting (WLS) fibre placed on the top and bottom of the arrays. On every other line, crystals that are 2 mm shorter are arranged to create grooves. WLS fibre is inserted into these grooves. This paper describes the design and performance evaluation of this PET detector using Monte Carlo simulations. To investigate sensitivity by crystal size, five types of PET detectors were simulated. Because the proposed detector is composed of crystals with three different lengths, degradation in sensitivity across the field of view was also explored by simulation. In addition, the effect of DOI resolution on image quality was demonstrated. The simulation results proved that the devised PET detector with excellent DOI resolution is helpful for reducing the channels of sensors/electronics and minimizing gamma ray attenuation and scattering while maintaining good detector performance.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.5
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• pp.519-524
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• 2009

This paper describes a new sensor system for 3D environment perception using stereo structured infrared light sources and a camera. Environment and obstacle sensing is the key issue for mobile robot localization and navigation. Laser scanners and infrared scanners cover $180^{\circ}$ and are accurate but too expensive. Those sensors use rotating light beams so that the range measurements are constrained on a plane. 3D measurements are much more useful in many ways for obstacle detection, map building and localization. Stereo vision is very common way of getting the depth information of 3D environment. However, it requires that the correspondence should be clearly identified and it also heavily depends on the light condition of the environment. Instead of using stereo camera, monocular camera and two projected infrared light sources are used in order to reduce the effects of the ambient light while getting 3D depth map. Modeling of the projected light pattern enabled precise estimation of the range. Two successive captures of the image with left and right infrared light projection provide several benefits, which include wider area of depth measurement, higher spatial resolution and the visibility perception.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1237-1242
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• 2017

Computer vision is coming more interesting with new imaging sensors' new capabilities which enable it to understand more its surrounding environment by imitating human vision system with artificial intelligence techniques. In this paper, we made experiments with Kinect camera, a new depth sensor for object detection and distance measurement functions, most essential functions in computer vision such as for unmanned or manned vehicles, robots, drones, etc. Therefore, Kinect camera is used here to estimate the position or the location of objects in its field of view and measure the distance from them to its depth sensor in an accuracy way by checking whether that the detected object is real object or not to reduce processing time ignoring pixels which are not part of real object. Tests showed promising results with such low-cost range sensor, Kinect camera which can be used for object detection and distance measurement which are fundamental functions in computer vision applications for further processing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.12
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• pp.1207-1215
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• 2013

This paper proposes the location estimation techniques of distributed targets with the multi-sensor data perceived through IR sensors of the military robots in consideration of obstacles. In order to match up targets with measured azimuths, to add to the depth-first search (DFS) algorithms in free-obstacle environment, we suggest the expanded DFS (EDS) algorithm including bypass path search, partial path search, middle level ending, and the supplementation of decision metric. After matching up targets with azimuths, we estimate the coordinate of each target by obtaining the intersection point of the azimuths with the least square error (LSE) algorithm. The experimental results show the error rate of estimated location, mean number of calculating nodes, and mean distance between real coordinates and estimated coordinates of the proposed algorithms.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.192-196
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• 2005

In this paper, we investigated the possibility of replicating patterned media by nano-injection molding process with a metallic nano-stamper. The original nano-master was fabricated by E-beam lithography and ICP etching process. The metallic nano-stamper was fabricated using a nanoimprint lithography and nano-electroforming process. The nano-patterned substrate was replicated using a nano-injection molding process without additional etching process. In nano-injection molding process, since the solidified layer, generated during the polymer filling, deteriorates transcribability of nano patterns by preventing the polymer melt from filling the nano cavities, an injection-mold system was constructed to actively control the stamper surface temperature using MEMS heater and sensors. The replicated polymeric patterns using nano-injection molding process were as small as 50 nm in diameter, 150 nm in pitch, and 50 nm in depth. The replicated polymeric patterns can be applied to high density patterned media.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.130-135
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• 2004

This paper presents a 3-D localization of an autonomous underwater vehicle(AUV). Conventional methods of localization, such as LBL or SBL, require additional beacon systems, which reduces the flexibility and availability of the AUV We use a digital compass, a pressure sensor, a clinometer and ultrasonic sensors for localization. From the orientation and velocity information, a priori position of the AUV is estimated based on the dead reckoning. With the aid of extended Kalman filter algorithm, a posteriori position of the AUV is estimated by using the distance between the AUV and a mother ship on the surface of the water together with the water depth information from the pressure sensor. Simulation results show the possibility of practical application of the method to autonomous navigation of the AUV.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.1
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• pp.24-29
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• 2005

Silicon nitride cantilevers integrated with silicon heaters and piezoelectric sensors were developed for the scanning probe microscope (SPM) based data storage application. These nitride cantilevers are expected to have better mechanical stability and uniformity of initial bending than the previously developed silicon cantilevers. Data bits of 40 nm in diameter were recorded on PMMA film and the sensitivity of the piezoelectric sensor was 0.615 fC/nm, meaning that indentations less than 20 nm in depth can be detected. For high speed operation, $128{\times}128$ cantilever array was developed.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.5
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• pp.434-443
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• 2007

Presently, the exploration of an unknown environment is an important task for thee new generation of mobile service robots and mobile robots are navigated by means of a number of methods, using navigating systems such as the sonar-sensing system or the visual-sensing system. To fully utilize the strengths of both the sonar and visual sensing systems. This paper presents a technique for localization of a mobile robot using fusion data of multi-ultrasonic sensors and vision system. The mobile robot is designed for operating in a well-structured environment that can be represented by planes, edges, comers and cylinders in the view of structural features. In the case of ultrasonic sensors, these features have the range information in the form of the arc of a circle that is generally named as RCD(Region of Constant Depth). Localization is the continual provision of a knowledge of position which is deduced from it's a priori position estimation. The environment of a robot is modeled into a two dimensional grid map. we defines a vision-based environment recognition, phisically-based sonar sensor model and employs an extended Kalman filter to estimate position of the robot. The performance and simplicity of the approach is demonstrated with the results produced by sets of experiments using a mobile robot.

• Journal of Sensor Science and Technology
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• v.3 no.3
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• pp.45-53
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• 1994

A new type of Si diaphragm was fabricated using Si-wafer direct bonding and two-step electrochemical etch-stopping methods. Using the new diaphragm structure in mechanical sensors, more precise control of cavity depth and diaphragm thickness was achievable. Also, the propagation of the stress, which was generated near the bonding interface, to the surface can be avoided. Finally, a piezoresistive-type Si pressure sensor was fabricated utilizing the diaphragm and a digital pressure gauge, which can display units of pressure, was realized.