• Journal of Intelligence and Information Systems
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• v.18 no.1
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• pp.1-21
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• 2012

In recent years, mobile phone has experienced an extremely fast evolution. It is equipped with high-quality color displays, high resolution cameras, and real-time accelerated 3D graphics. In addition, some other features are includes GPS sensor and Digital Compass, etc. This evolution advent significantly helps the application developers to use the power of smart-phones, to create a rich environment that offers a wide range of services and exciting possibilities. To date mobile AR in outdoor research there are many popular location-based AR services, such Layar and Wikitude. These systems have big limitation the AR contents hardly overlaid on the real target. Another research is context-based AR services using image recognition and tracking. The AR contents are precisely overlaid on the real target. But the real-time performance is restricted by the retrieval time and hardly implement in large scale area. In our work, we exploit to combine advantages of location-based AR with context-based AR. The system can easily find out surrounding landmarks first and then do the recognition and tracking with them. The proposed system mainly consists of two major parts-landmark browsing module and annotation module. In landmark browsing module, user can view an augmented virtual information (information media), such as text, picture and video on their smart-phone viewfinder, when they pointing out their smart-phone to a certain building or landmark. For this, landmark recognition technique is applied in this work. SURF point-based features are used in the matching process due to their robustness. To ensure the image retrieval and matching processes is fast enough for real time tracking, we exploit the contextual device (GPS and digital compass) information. This is necessary to select the nearest and pointed orientation landmarks from the database. The queried image is only matched with this selected data. Therefore, the speed for matching will be significantly increased. Secondly is the annotation module. Instead of viewing only the augmented information media, user can create virtual annotation based on linked data. Having to know a full knowledge about the landmark, are not necessary required. They can simply look for the appropriate topic by searching it with a keyword in linked data. With this, it helps the system to find out target URI in order to generate correct AR contents. On the other hand, in order to recognize target landmarks, images of selected building or landmark are captured from different angle and distance. This procedure looks like a similar processing of building a connection between the real building and the virtual information existed in the Linked Open Data. In our experiments, search range in the database is reduced by clustering images into groups according to their coordinates. A Grid-base clustering method and user location information are used to restrict the retrieval range. Comparing the existed research using cluster and GPS information the retrieval time is around 70~80ms. Experiment results show our approach the retrieval time reduces to around 18~20ms in average. Therefore the totally processing time is reduced from 490~540ms to 438~480ms. The performance improvement will be more obvious when the database growing. It demonstrates the proposed system is efficient and robust in many cases.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1103-1109
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• 2014

The motion recognition system has been broadly studied in digital image and video processing fields. Recently, method using th depth image is used very useful. However, recognition accuracy of depth image based method will be loss caused by size and shape of object distorted for angle of the depth sensor. Therefore, distortion correction of depth sensor is positively necessary for distinguished performance of the recognition system. In this paper, we propose a pre-processing algorithm to improve the motion recognition system. Depth data from depth sensor converted to real world, performed the corrected angle, and then inverse converted to projective world. The proposed system make progress using the OpenCV and the window program, and we test a system using the Kinect in real time. In addition, designed using Verilog-HDL and verified through the Zynq-7000 FPGA Board of Xilinx.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.157-166
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• 2007

This study was to compare the major kinematic factors between the success and failure group on performing the back somersault motion in floor exercise. Three gymnasts(height : $167.3{\pm}2.88cm$, age : $22.0{\pm}1.0years$, body weight : $64.4{\pm}2.3kg$) were participated in this study. The kinematic data was recorded at 60Hz with four digital video camera. Two successful motions and failure motions for each subject were selected for three dimensional analysis. 1. Success Trail It was appear that success trail was larger than failure group in projection velocity, but success trail was smaller than failure trail in projection angle. Also it was appear that success trail was longer than failure group in the time required. Hand segment velocity and maximum velocity in success trail were larger than those in failure trail, and this result was increasing the projection velocity and finally increasing the vertical height of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle was contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle was maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of success trail extended more than those of failure trail. in this base, success trail in upward phase(p3) 2. Failure Trail It was appear that failure trail was smaller than success trail in projection velocity, but failure trail was larger than success trail in projection angle. Also it was appear that failure trail was more short than success trail in the time required. Hand segment velocity and maximum velocity in failure trail were smaller than those in success trail, and this result was reducing the projection velocity and finally reducing the vertical high of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle wasn't contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle wasn't maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of failure trail didn't extended more than those of success trail.

• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.345-354
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• 2005

Since motion estimation and motion compensation methods remove the redundant data to employ the temporal redundancy in images, it plays an important role in digital video compression. Because of its high computational complexity, however, it is difficult to apply to high-resolution applications in real time environments. If we have a priori knowledge about the motion of an image block before the motion estimation, the location of a better starting point for the search of an exact motion vector can be determined to expedite the searching process. In this paper presents the motion detection algorithm that can run robustly about recusive motion. The motion detection compares and analyzes two frames each other, motion of whether happened judge. Through experiments, we show significant improvements in the reduction of the computational time in terms of the number of search steps without much quality degradation in the predicted image.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.127-142
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• 2005

The purpose of this study was to analysis biomechanics of the lower extremities injury the heights(40cm, 60cm, 80cm) of jump box as performed depth jump motion by 6 females aerobic athletes and 6 non-experience females students. The event of depth jump were set to be drop, landing and jump. The depth jump motions on the force plate were filmed using a digital video cameras, and data were collected through the cinematography and force plate. On the basis of the results analyzed, the conclusions were drawn as follows: 1. The landing time of skill group was shorter than unskill group at 40cm, 60cm drop height during drop-landing-jump phase especially. The landing time of 60cm drop height was significant between two group(p<.05). 2. The peak GRF of sagittal and frontaI direction following drop height improve was variety pattern and the peak vertical force of 40cm drop height was significantly(p<.05). 3. The magnitude of peak passive force was not increase to change the drop height. 4. The peak passive forces was significant at 40cm drop height between two groups(p<.05)

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.265-276
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• 2003

The objective of this research is to provide basic data for improving athletic performances, suggesting methods that can be utilized at games and coaching movements in the snatch, by analyzing the level of contribution of muscles to the movements of the snatch lift through three-dimensional imaging and EMG analysis between skilled and unskilled lifters. To this end, three high school students (the skilled group), three middle school student (the unskilled group) were selected; two digital video cameras and electromyography were used. The muscles measured by an EMG include gastrocnemius muscle, biceps femoris muscle, erector spinae, latissimus dorsi muscle, trapezius muscle, and brachioradialis. Based on the Ariel Performance Analysis System (APAS) program, the results of the analysis are summarized as follows. 1. In performing snatch pulls, the skilled lifters were found to simultaneously move the weight centers of the body and the barbell close to vertical, close to the shoulders in the pulling portion; in snatching and grabbing the barbell from a sited position, it was observed that the shorter the time for adjusting to change in the height of the barbell by using rotational inertia, the better it is to perform the movements. 2. The skilled lifters were observed to perform stable and efficient movements in grabbing the bar in a sited position, by moving the barbell and weight center of the body close to vertical and moving the shoulder joint under the bar fast. 3. The results of the EMG analysis of the entire movements from the snatching portion to the portion of grabbing the bar in a sited position show that when the skilled lifters lifted the barbell vertically during the pulling portion, their shoulder joints were extended to put more weight on biceps femoris muscle and brachioradialis; and in snatching and grabbing the bar from a sited position, it was found desirable to increase the myoelectrical activity of erector spinae in order to achieve a balance in the movements of the hip joint between font and rear, as the weight centers of the body and the barbell move higher. On the other hand, the unskilled lifters were found that in response to change in posture, they increase their muscular strength inefficiently in performing the movements throughout the entire lifting process.

• Journal of the Korean School Mathematics Society
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• v.15 no.3
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• pp.565-584
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• 2012

This study investigates how the GSP helps gifted and talented students understand geometric principles and concepts during the inquiry process in the generalization of the internal triangle, and how the students logically proceeded to visualize the content during the process of generalization. Four mathematically gifted students were chosen for the study. They investigated the pattern between the area of the original triangle and the area of the internal triangle with the ratio of each sides on m:n respectively. Digital audio, video and written data were collected and analyzed. From the analysis the researcher found four results. First, the visualization used the GSP helps the students to understand the geometric principles and concepts intuitively. Second, the GSP helps the students to develop their inductive reasoning skills by proving the various cases. Third, the lessons used GSP increases interest in apathetic students and improves their mathematical communication and self-efficiency.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.6
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• pp.43-50
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• 2007

In this paper we propose a method that identifies users at H.264 streaming using watermarking with fingerprints. The watermark can efficiently reduce the potential danger of forgery or alteration. Especially a biometric watermark has various advantages. Among entire biometric characteristics, the fingerprint is the most convenient and economical. In this paper we propose a novel fingerprint-based watermarking technique that can survive under very low bit-rate compression. The proposed algorithm consists of enhancement of a fingerprint image, the watermark generation using the extracted feature coordinates, watermark insertion using discrete wavelet transform, and authentication. The proposed algorithm can achieve robust watermark extraction against 0.264 compressed videos.

• The Journal of Korean Association of Computer Education
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• v.10 no.1
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• pp.77-88
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• 2007

More flexible learning models are needed, and learning environments that operate through mobile technologies such as portable multimedia players(PMP) provide useful tools in implementing these learning models. The main attractant of PMP is often their versatility: being able to load and play different formats of video, audio, digital images, and interactive media. In this paper, we investigate the factors influencing the usage and acceptance of the PMP for study, based on the extended version of the Technology Acceptance Model (TAM). Based on data collected from online survey, we show that perceived usefulness, perceived ease of use, flow and perceived enjoyment are the major determinants for users to play PMP for study purpose. Factors, including ease of use, contents-credibility are shown to determine the level of perceived usefulness; additionally, perceived usefulness, ease of use and perceived enjoyment are shown to directly affect the level of flow. Based upon the statistical results, some useful guidelines for developing learning contents are also provided.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.7
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• pp.380-388
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• 2014

Transmission methods for terrestrial UHDTV broadcasting have been actively studied in order to provide enhanced broadcasting service in many countries. Most of the countries are considering multi-carrier transmission methods based on OFDM and some of them have performed UHDTV experimental broadcasting by using the DVB-T2 standard with the adoption of an improved data compression technique. However, since single carrier transmission methods, which are known to be susceptible to multi-path fading, could remedy this defect by using the SC-FDE method where a frequency domain equalizer is utilized in the receiver, they may achieve a similar transmission performance with multi-carrier transmission methods. In consideration of these circumstances, we compare the transmission performances of two-type methods to provide a decision criterion on a suitable transmission method for UHDTV broadcasting.