• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.723-743
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• 2016

Indoor positioning is considered an enabler for a variety of applications, the demand for an indoor positioning service has also been accelerated. That is because that people spend most of their time indoor environment. Meanwhile, the smartphone integrated powerful camera is an efficient platform for navigation and positioning. However, for high accuracy indoor positioning by using a smartphone, there are two constraints that includes: (1) limited computational and memory resources of smartphone; (2) users' moving in large buildings. To address those issues, this paper uses the TC-OFDM for calculating the coarse positioning information includes horizontal and altitude information for assisting smartphone camera-based positioning. Moreover, a unified representation model of image features under variety of scenarios whose name is FAST-SURF is established for computing the fine location. Finally, an optimization marginalized particle filter is proposed for fusing the positioning information from TC-OFDM and images. The experimental result shows that the wide location detection accuracy is 0.823 m (1σ) at horizontal and 0.5 m at vertical. Comparing to the WiFi-based and ibeacon-based positioning methods, our method is powerful while being easy to be deployed and optimized.

• ETRI Journal
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• v.37 no.4
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• pp.766-771
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• 2015

Robust motion estimation for human-computer interactions played an important role in a novel method of interaction with electronic devices. Existing pose estimation using a monocular camera employs either ego-motion or exo-motion, both of which are not sufficiently accurate for estimating fine motion due to the motion ambiguity of rotation and translation. This paper presents a hybrid vision-based pose estimation method for fine-motion estimation that is specifically capable of extracting human body motion accurately. The method uses an ego-camera attached to a point of interest and exo-cameras located in the immediate surroundings of the point of interest. The exo-cameras can easily track the exact position of the point of interest by triangulation. Once the position is given, the ego-camera can accurately obtain the point of interest's orientation. In this way, any ambiguity between rotation and translation is eliminated and the exact motion of a target point (that is, ego-camera) can then be obtained. The proposed method is expected to provide a practical solution for robustly estimating fine motion in a non-contact manner, such as in interactive games that are designed for special purposes (for example, remote rehabilitation care systems).

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.57-61
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• 2021

A formation process of indium bump arrays on micro-pillar structures is proposed. The space to form indium bump on the narrow structures can be secured applying the benzocyclobutene (BCB) planarization and its etch-back process. We exhibit a detailed overview of the process steps involved in the fabrication of 320×256 hybrid camera sensor for short-wavelength infrared (SWIR) detection. The shear strength of the BCB, which has undergone the different processes, is extracted by quartz crystal microbalance measurement. The shear strength of the BCB is three orders of magnitude higher than that of the indium bump itself. The measured dark current distribution of the fabricated SWIR camera sensor indicates the suggested process of indium bumps can be useful for embodying highly sensitive infared camera sensors.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.9
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• pp.81-92
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• 1998

A new hybrid technique using several sub-populations having completely different evolutionary behaviors is proposed to increase the possibility to quickly find the global optimum of continuous optimization problem. It has three sub-populations. Two NPOSA algorithms showing good performance in the problem having a rugged fitness function are applied to two sub-populations and a self-adaptive evolutionary algorithm to the other sub-population. Sub-populations evolve in different manners and the interaction among these sub-populations lead to the global optimum quickly. The efficiency of this technique is verified through benchmark test functions. Finally, the algorithm with three sub-populations has been applied to seek for the optimal camera calibration parameters. After an error function has been defined using measured feature points of a calibration block, it has been shown that the algorithm searches for the camera parameters that minimize the error function.

• Smart Structures and Systems
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• v.20 no.4
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• pp.397-413
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• 2017

Precast concrete (PC) members are currently being employed for general construction or partial replacement to reduce construction period. As assembly work in PC construction requires connecting PC members accurately, measuring the 6-DOF (degree of freedom) relative displacement is essential. Multiple planar markers and camera-based displacement measurement systems can monitor the 6-DOF relative displacement of PC members. Conventional methods, such as direct linear transformation (DLT) for homography estimation, which are applied to calculate the 6-DOF relative displacement between the camera and marker, have several major problems. One of the problems is that when the marker is partially hidden, the DLT method cannot be applied to calculate the 6-DOF relative displacement. In addition, when the images of markers are blurred, error increases with the DLT method which is employed for its estimation. To solve these problems, a hybrid method, which combines the advantages of the DLT and MCL (Monte Carlo localization) methods, is proposed. The method evaluates the 6-DOF relative displacement more accurately compared to when either the DLT or MCL is used alone. Each subsystem captures an image of a marker and extracts its subpixel coordinates, and then the data are transferred to a main system via a wireless communication network. In the main system, the data from each subsystem are used for 3D visualization. Thereafter, the real-time movements of the PC members are displayed on a tablet PC. To prove the feasibility, the hybrid method is compared with the DLT method and MCL in real experiments.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.239-245
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• 2000

In this paper, the fundamental properties of diffractive optical element were investigated. Also, this work deals with theoretical approaches for achromatization in DOE's optical system based on thin lens theory. It is found that achromatization could be satisfied by one hybrid lens only, which is composed of a diffractive and a refractive element. In order to have compact optical system, we used the tele-photo type lens composed of a positive and a negative power elements instead of retro-focus lens. From the Gaussian brackets and Seidel aberration theory, the initial design was numerically obtained. The aberration properties of an initial design was aplanat and flat field. In order to correct the chromatic aberrations, refractive and diffractive elements were used on front element. This hybrid lens is also useful for correction of higher order aberrations. Compared to conventional design composed of refractive lenses only, this approach dramatically improved the compactness of the optical system. Finally, residual aberration balancing results in a lens with focal length of 3.89 mm and overall length of 5.19 mm, which has enough performance over an f-number of 4.0. Also, it is expected to fulfill all the requirements of a digital still camera lens. This optical system is superior to the current refractive lens system in the number of elements, weight, and aberration properties. rties.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.157-163
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• 2011

This paper proposes a hybrid image stabilizing system which uses both optical image stabilizing system based on EKF (Extended Kalman Filter) and digital image stabilization based on SURF (Speeded Up Robust Feature). Though image information is one of the most efficient data for object recognition, it is susceptible to noise which results from internal vibration as well as external factors. The blurred image obtained by the camera mounted on a robot makes it difficult for the robot to recognize its environment. The proposed system estimates shaking angle through EKF based on the information from inclinometer and gyro sensor to stabilize the image. In addition, extracting the feature points around rotation axis using SURF which is robust to change in scale or rotation enhances processing speed by removing unnecessary operations using Hessian matrix. The experimental results using the proposed hybrid system shows its effectiveness in extended frequency range.

• Journal of Welding and Joining
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• v.24 no.4
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• pp.22-26
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• 2006

In lap welding of zinc-coated steel, porosity formation is one of most significant weld defects, which is caused by zinc vapor generated between the steel sheets. Various solutions have been proposed in the past years but development of more effective method is a worthwhile subject to be investigated. In this study, autogenous laser welding and laser-TIG hybrid welding was applied to the lap welding of zinc-coated steel without gap, and weld pool behaviors were observed by using high speed camera and the porosity generation mechanism was analyzed. The weld defects were successfully eliminated by laser-TIG hybrid welding. This is because the leading TIG arc partially melted the upper sheet and vaporized/oxidized the coated zinc on the lapped surfaces prior to the trailing laser illuminating the specimen.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.304-309
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• 2014

In this paper, we design a hybrid wheeled and legged mobile robot with a waist joint. The proposed hybrid mobile robot is designed to have a hybrid structure with leg and wheel for the efficient movement in flat and uneven surfaces. The proposed robot have a waist joint that is used to stably transform from wheeled driving to legged walking of the robot and to overcome non-flat surface. In order to recognize various environments we use LRF sensor, PSD sensor, CCD camera. Also, a motion planning method for hybrid mobile robot with a waist joint is proposed to select wheeled driving motion and legged walking motion of the robot based the environment types. We verify the efficient mobility of the developed hybrid mobile robot through navigation experiments using the proposed motion planning method in various environments.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.807-812
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• 2016

Transparent film heaters (TFHs) based on Joule heating are currently an active research area. However, TFHs based on an indium tin oxide (ITO) monolayer have a number of problems. For example, heating is concentrated in only part of the device. Also, heating efficiency is low because it has high sheet resistance ($R_s$). To address these problems, this study introduced hybrid layers of ITO/Ag/ITO deposited by magnetron sputtering, and the electrical, optical, and thermal properties were estimated for various thicknesses of the metal interlayer. The $R_s$ of ITO(40)/Ag/ITO(40 nm) hybrid TFHs were 5.33, 3.29 and $2.15{\Omega}/{\Box}$ for Ag thicknesses of 10, 15, and 20 nm, respectively, while the $R_s$ of an ITO monolayer (95 nm) was $59.58{\Omega}/{\Box}$. The maximum temperatures of these hybrid TFHs were 92, 131, and $145^{\circ}C$, respectively, under a voltage of 3 V. And that of the ITO monolayer was only $32^{\circ}C$. For the same total thickness of 95 nm, the heat generation rate (HGR) of the hybrid produced a temperature approximately $100^{\circ}C$ higher than the ITO monolayer. It was confirmed that the film with the lowest $R_s$ of the samples had the highest HGR for the same applied voltage. Overall, hybrid layers of ITO/Ag/ITO showed excellent performance for HGR, uniformity of heat distribution, and thermal response time.