• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.623-628
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• 2008

We present a new method of extracting foreground object from background image for vision-based game interface. Background Subtraction is an important preprocessing step for extracting the features of tracking objects. The image is divided into the cells where the Local Histogram with Gaussian kernel is computed and compared with the corresponding one using Bhattacharyya distance measure. The histogram-based method is partially robust against illumination change, noise and small moving objects in background. We propose a Multi-Scaled Integral Histogram approach for noise suppression and fast computation.

• Journal of Electrical Engineering and information Science
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• v.3 no.2
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• pp.230-238
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• 1998

When size and shape of moving object have been changed, a correlator often accumulates walk-off error. A success of correlation-based tracking largely depends on choosing suitable window size and position and thus transferring the proper reference image to the next frame. For this, we propose the Adaptive Window Algorithm with Four-Direction Sizing Factors (AWA-FSF) for fast adjusting a reference region to enhance reliability of correlation-based image tracking in complex cluttered environments. Since the AWA-FSF is capable of adjusting a reference image size more rapidly and properly, we can minimize the influence of complex background and clutter. In addition, we can finely tune the center point of the reference image repeatedly after main tracking process. Thus we have increased stability and reliability of correlation-based image tracking. We tested performance of the AWA-FSF using 45 real image sequences made of over 3400 images and had the satisfied results for most of them.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.443-446
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• 2002

Wake downstream of an object in the stratified flow has been of long-standing interest in fluid dynamics because of its similarity to geophysical flow over topographical terrains and more recently, concerns about the wake left behind a body moving through the ocean thermocline. Decades of studies of geophysical flow have unveiled that the flow downstream of obstacles in stratified flow consists of attached wake and strong internal waves, or separated, fluctuating wake and persistent late wakes, all of which depend on the flow conditions. Among unique and interesting characteristics of the stratified flow past obstacles is the generation of coherent vortex structure in the late wake far downstream of the object. Without the density stratification, the flow field downstream becomes undisturbed after relatively fast diminishing of the near wake. However, no matter how small the stratification is, the flow field downstream self-develops coherent vortex structures even after diminishing of the near wake. This paper present a computational approach to simulate the generation mechanism of the coherent vortex and analysis of the vortical structure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.406-412
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• 2003

A fast multiple object motion detection method using periodogram has been proposed. Each frame is projected to vertical and horizontal directions, and then temporal FFT is applied. A line in two dimensional frequency domain indicates velocity. To estimate the velocity of an object, we intergrate along a line which passes through the origin in frequency domain. If a frame contains multiple moving objects, multiple peaks are detected corresponding to the velocity of each object. After pairing these peaks, we can determine the velocities of an object. In the proposal method we can easily pair horizontal and vertical velocity components efficiently with simple computation by combining projections in 45$^{\circ}$ and 135 $^{\circ}$ directions in addition to the vertical and horizontal direction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.5
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• pp.271-280
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• 2014

In wireless sensor networks, there have been two methods for sensing continuously moving object tracking: user-query based method and periodic report based method. Although the former method requires overhead for user query rather than the latter method, the former one is known as an energy-efficient method without transferring unnecessary information. In the former method, a virtual tree, consisting of sensor nodes, is exploited for the user querying and sensor reporting. The tree stores the information about mobile objects; the stored information is triggered to report by the user query. However, in case of fast moving object, the tracking accuracy reduces due to the time delay of end-to-end repeated query. To solve the problem, we propose a query relaying method reducing the time delay for mobile object tracking. In the proposed method, the nodes in the tree relay the query to the adjacent node according to the movement of mobile object tracking. Relaying the query message reduces the end-to-end querying time delay. Simulation results show that our method is superior to the existing ones in terms of tracking accuracy.

• Journal of Broadcast Engineering
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• v.21 no.1
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• pp.11-23
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• 2016

Recent days, touch interaction interface is the most widely used interaction interface to communicate with digital devices. Because of its usability, touch technology is applied almost everywhere from watch to advertising boards and it is growing much bigger. However, this technology has a critical weakness. Normally, touch input device needs a contact surface with touch sensors embedded in it. Thus, touch interaction through general objects like books or documents are still unavailable. In this paper, a human-object interaction framework based on RGB-D camera is proposed to overcome those limitation. The proposed framework can deal with occluded situations like hovering the hand on top of the object and also moving objects by hand. In such situations object recognition algorithm and hand gesture algorithm may fail to recognize. However, our framework makes it possible to handle complicated circumstances without performance loss. The framework calculates the status of the object with fast and robust object recognition algorithm to determine whether it is an object or a human hand. Then, the hand gesture recognition algorithm controls the context of each object by gestures almost simultaneously.

• The KIPS Transactions:PartD
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• v.16D no.3
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• pp.317-326
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• 2009

Recently, there have been many research efforts proposed on trajectory information. Most of them mainly focus their attention on those objects moving in Euclidean space. Many real-world applications such as telematics, however, deal with objects that move only over road networks, which are highly restricted for movement. Thus, the existing methods targeting Euclidean space cannot be directly applied to the road network space. This paper proposes a new clustering scheme for a large volume of trajectory information of objects moving over road networks. To the end, we first define a trajectory on a road network as a sequence of road segments a moving object has passed by. Next, we propose a similarity measurement scheme that judges the degree of similarity by considering the total length of matched road segments. Based on such similarity measurement, we propose a new clustering algorithm for trajectories by modifying and adjusting the FastMap and hierarchical clustering schemes. To evaluate the performance of the proposed clustering scheme, we also develop a trajectory generator considering the observation that most objects tend to move from the starting point to the destination point along their shortest path, and perform a variety of experiments using the trajectories thus generated. The performance result shows that our scheme has the accuracy of over 95% in comparison with that judged by human beings.

• Journal of KIISE:Databases
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• v.31 no.1
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• pp.39-47
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• 2004

Spatio-temporal databases have been mostly studied in the area of access methods. However, without considering an extraordinary update maintenance overhead after building up a spatio-temporal index, most indexing techniques have focused on fast query processing only. In this paper, we propose an efficient update management method that reduces the number of disk accesses required in order to apply the updates of moving objects to a spatio-temporal index. We consider realistic update patterns that can represent the movements of objects properly. We present a memory based structure that can efficiently maintain a small number of very frequently updating objects. For an experimental environment with realistic update patterns, the number of disk accesses of our method is about 40% lower than that of a general update method of existing spatio-temporal indexes.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1824-1827
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• 1998

A Laser Doppler Vibrometer(LDV) was developed using He-Ne laser as a light source. The heterodyne method was employed and its output signal was digitally processed with a $\mu$-processor and the result was displayed with LCD. The frequency shifted object beam(40 MHz) by a Bragg cell was focused on the surface of the moving target and the Doppler shifted reflected beam was recombined with reference beam at the fast photodetector to produce frequency modulated signal centered at 40 MHz. The signal from the detector was amplified and downconverted to intermediate frequency centered at 1 MHz after mixing process. The voltage output that was proportional to the velocity of the moving surface was obtained using PLL. With the same method, the fringe pattern signal of the moving surface is obtained. This fringe pattern signal is converted to TTL signal with ZCD(zero-crossing detector) and then counted to calculate the displacement due to the vibration, which is displayed with LCD. This LDV can be used to measure the resonant frequency of the electric equipments such as circuit breakers and transformers, of which resonant frequencies are changed when they are damaged.

• Journal of KIISE:Databases
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• v.35 no.5
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• pp.447-458
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• 2008

In this paper, we address an efficient processing scheme for k-nearest neighbor queries to retrieve k static objects in road network databases. Existing methods cannot expect a query processing speed-up by index structures in road network databases, since it is impossible to build an index by the network distance, which cannot meet the triangular inequality requirement, essential for index creation, but only possible in a totally ordered set. Thus, these previous methods suffer from a serious performance degradation in query processing. Another method using pre-computed network distances also suffers from a serious storage overhead to maintain a huge amount of pre-computed network distances. To solve these performance and storage problems at the same time, this paper proposes a novel approach that creates an index for moving objects by approximating their network distances and efficiently processes k-nearest neighbor queries by means of the approximate index. For this approach, we proposed a systematic way of mapping each moving object on a road network into the corresponding absolute position in the m-dimensional space. To meet the triangular inequality this paper proposes a new notion of average network distance, and uses FastMap to map moving objects to their corresponding points in the m-dimensional space. After then, we present an approximate indexing algorithm to build an R*-tree, a multidimensional index, on the m-dimensional points of moving objects. The proposed scheme presents a query processing algorithm capable of efficiently evaluating k-nearest neighbor queries by finding k-nearest points (i.e., k-nearest moving objects) from the m-dimensional index. Finally, a variety of extensive experiments verifies the performance enhancement of the proposed approach by performing especially for the real-life road network databases.