• Journal of the Korea Computer Graphics Society
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• v.25 no.5
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• pp.11-20
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• 2019

With the development of deep learning technology, research is being actively carried out on user-friendly interfaces that are suitable for use in virtual reality or augmented reality applications. To support the interface using the user's hands, this paper proposes a deep learning-based fingertip detection method to enable the tracking of fingertip coordinates to select virtual objects, or to write or draw in the air. After cutting the approximate part of the corresponding fingertip object from the input image with the Grad-CAM, and perform the convolution neural network with Atrous Convolution for the cut image to detect fingertip location. This method is simpler and easier to implement than existing object detection algorithms without requiring a pre-processing for annotating objects. To verify this method we implemented an air writing application and showed that the recognition rate of 81% and the speed of 76 ms were able to write smoothly without delay in the air, making it possible to utilize the application in real time.

• Journal of Korea Game Society
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• v.9 no.5
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• pp.105-115
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• 2009

This article proposes a design and implementation methodology of a gesture-based interface for augmented reality games. The topic of gesture-based augmented reality games is a promising area in the immersive future games using human body motions. However, due to the instability of the current motion recognition technologies, most previous development processes have introduced many ad hoc methods to handle the shortcomings and, hence, the game architectures have become highly irregular and inefficient This article proposes an efficient development methodology for gesture-based augmented reality games through prototyping a table tennis game with a gesture interface. We also verify the applicability of the prototyping mechanism by implementing and demonstrating the augmented reality table tennis game. In the experiments, the implemented prototype has stably tracked real rackets to allow fast movements and interactions without delay.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.322-332
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• 2011

In this paper, we introduce the 1st performance evaluation of VLBI Correlation Subsystem (VCS) main product, which is core system of Korea-Japan Joint VLBI Correlator (KJJVC). The main goal of the 1st performance evaluation of VCS main product is that the perfection of overall system will be enhanced after checking the unsolved part by performing the experiments towards various test items at the manufacturer before installation of field. The functional test was performed by including the overflow problem occurred in the FFT re-quantization module due to the insufficient of effective bit at the VCS trial product in this performance test of VCS main product. Through the performance test for VCS main product in the factory, the problem such as FFT re-quantization discovered at performance test of VCS trial product in 2008 was clearly solved and the important functions such as delay tracking, daly compensation, and frequency bining were added in this VCS main product. We also confirmed that the predicted correlation results (fringe) was obtained in the correlation test by using real astronomical observed data(wideband/narrow band).

• Journal of Internet Computing and Services
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• v.8 no.1
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• pp.1-14
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• 2007

IF handoff events are occurred during the transmission of multimedia traffic, the efficient resource allocation and handoff procedures are necessary to maintain the same QoS of transmitted multimedia traffic because the QoS may be defected by some delay and information loss, This paper proposes a handoff scheme to accommodate multimedia traffic based on the resource reservation procedure using direction estimation, This scheme uses a novel mobile tracking method based on Fuzzy Multi Criteria Decision Making, in which uncertain parameters such as PSS (Pilot Signal Strength), the distance between the mobile and the base station, the moving direction, and the previous location are used in the decision process using the aggregation function in fuzzy set theory, With the position information, the moving direction is determined, The handoff requests for real time sessions are handled based on the direction prediction and the resource reservation scheme, The resources in the estimated adjacent cells should be reserved and allocated to guarantee the continuity of the real time sessions, Through simulation results, we show that our proposed resource reservation method provides a better performance than that of the conventional method.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.127-138
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• 2008

Vehicles have recently become one of the main factors affecting our quality of life, and the needs of vehicles are still increasing. As a result, the growth of vehicles generate more crashes every year. One main factor for vehicle crashes is uncareful driving behaviors. Especially, drowsy or fatigue driving behaviors explain about 10-20% of the crashes, and they cause serious results because of the delay of response time and the decrease of object-recognition. Therefore, this research conducted real time image processing tests in order to study how cellular phone usages and drowy(or fatigue) drives affect driving behaviors. A vehicle simulator was used for this research, and the faceLAB 4.5 of Seeing Machines for eye image tracking tests using a small camera was installed in the front of the simulator, and normal and drowsy(or fatigue) driving patterns were analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1B
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• pp.86-97
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• 2009

RTLS is a system for automatically locating and tracking people and objects. The TDOA-based RTLS determines the location of the tag by calculating the time differences of a signal received from the tag. In TDOA-based RTLS, time synchronization is essential to calculate the time difference between readers. This paper presents a precision time synchronization method for TDOA-based RTLS over IEEE 802.15.4. In order to achieve precision time synchronization in IEEE 802.15.4 radio, we analyzed the error factors of delay and jitter. We also deal with the implementation of hardware assisted time stamping and the Kalman filtering method to minimize the error factors. In addition, this paper described the experiments and performance evaluation of the proposed precision time synchronization method in IEEE 802.15.4 radio. The results show that the nodes in a network can maintain their clocks to within 10 nanoseconds offset from the reference clock.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1110-1121
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• 2016

The mathematical model of a three phase PWM converter under the stationary αβ reference frame is deduced and constructed based on a Proportional-Resonant (PR) regulator, which can replace trigonometric function calculation, Park transformation, real-time detection of a Phase Locked Loop and feed-forward decoupling with the proposed accurate calculation of the inductance voltage vector. To avoid the parallel resonance of the LCL topology, the active damping method of the proportional capacitor-current feedback is employed. As to current vector error elimination, an optimized PR controller of the inner current loop is proposed with the zero-pole matching (ZPM) and cancellation method to configure the regulator. The impacts on system's characteristics and stability margin caused by the PR controller and control parameter variations in the inner-current loop are analyzed, and the correlations among active damping feedback coefficient, sampling and transport delay, and system robustness have been established. An equivalent model of the inner current loop is studied via the pole-zero locus along with the pole placement method and frequency response characteristics. Then, the parameter values of the control system are chosen according to their decisive roles and performance indicators. Finally, simulation and experimental results obtained while adopting the proposed method illustrated its feasibility and effectiveness, and the inner current loop achieved zero static error tracking with a good dynamic response and steady-state performance.

• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.29-35
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• 2013

In this paper, we investigate the type and detection methode of spoofing attack, and then analyze the performance of spoofing detection algorithm in GPS L1 signal through the simulation. Generally spoofer is different from the jammer, because the receiver can be operated and not. In case of spoofing the GPS receiver is hard to recognize the spoofing attack and can be operated normally without stopping because the spoofing signal is the mimic GPS signal. To evaluate the performance of spoofing detection algorithm, both the software based spoofing and GPS signal generator and the software based GPS receiver are implemented. In paper, we can check that spoofing signal can affect to the DLL and PLL tracking loop because code delay and doppler frequency of spoofing. The spoofing detection algorithm has been implemented using the pseudorange, signal strength and navigation solution of GPS receiver and proposed algorithm can effectively detect the spoofing signal.

• Journal of Practical Engineering Education
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• v.14 no.2
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• pp.341-350
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• 2022

In this paper, we propseded the Youngwoo keyboard to help the communication disorders experienced by patients with dysarthria. Existing methods for communication by patients with dysarthria include a letter board with consonants and vowels, a mouse using eye tracking, and communication assistance applications. However, there was a delay of more than 5 minutes per sentence, so there were many difficulties in communication. However, unlike the existing method, the proposed method has been improved so that the patient with dysarthria can communicate by completing the sentences with eye movements. In the conclusion and future work of this paper, the educational use value for Yeongwoo keyboard was analyzed, and it was shown that this training can be of great help to families with ALS patients. The proposed keyboard will be able to improve the difficulties of families by facilitating communication of patients with dysarthria.

• Journal of Ginseng Research
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• v.47 no.2
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• pp.210-217
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• 2023

Background: Effects of the major ginsenoside Rg1 on mammalian longevity and physical vitality are rarely reported. Purpose: To examine longevity, tumor, and spontaneous locomotor activity in rats consuming Rg1. Methods: A total of 138 Wistar rats were randomized into 2 groups: control (N = 69) and Rg1 (N = 69). Rg1 (0.1 mg/kg per day) were orally supplemented from 6 months of age until natural death. Spontaneous mobility was measured by video-tracking together with body composition (dual energy x-ray absorptiometry) and inflammation markers at 5, 14, 21, and 28 months of age. Results: No significant differences in longevity (control: 706 days; Rg1: 651 days, p = 0.77) and tumor incidence (control: 19%; Rg1: 12%, p = 0.24) were observed between the two groups. Movement distance in the control group declined significantly by ~60% at 21 months of age, together with decreased TNF-α (p = 0.01) and increased IL-10 (p = 0.02). However, the movement distance in the Rg1 group was maintained ~50% above the control groups (p = 0.01) at 21 months of age with greater magnitudes of TNF-α decreases and IL-10 increases. Glucose, insulin, and body composition (bone, muscle and fat percentages) were similar for both groups during the entire observation period. Conclusion: The results of the study suggest a delay age-dependent decline in physical vitality during late life by lifelong Rg1 consumption. This improvement is associated with inflammatory modulation. Significant effects of Rg1 on longevity and tumorigenesis were not observed.