• Journal of the Korea Computer Graphics Society
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• v.23 no.1
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• pp.25-32
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• 2017

This paper proposes a novel acceleration method for particle based large scale fluid simulation. Traditional particle-based fluid simulation has been implemented by interacting with physical quantities of neighbor particles through the Smoothed Particle Hydrodynamics(SPH) technique[1]. SPH method has the characteristic that there is no visible change compared to the computation amount in a part where the particle movement is small, such as a calm surface or inter-fluid. This becomes more prominent as the number of particles increases. Previous work has attempted to reduce the amount of spare computation by adaptively dividing each part of the fluid. In this paper, we propose a technique to calculate the motion of the entire particles by using the physical quantities of the near sampled particles by sampling the particles inside the fluid at regular intervals and using them as reference points of the fluid motion. We propose a technique to adaptively generate a triangle map based on the position of the sampled particles in order to efficiently search for nearby particles, and we have been able to interpolate the physical quantities of particles using the barycentric coordinate system. The proposed acceleration technique does not perform any additional correction for two classes of fluid particles. Our technique shows a large improvement in speed as the number of particles increases. The proposed technique also does not interfere with the fine movement of the fluid surface particles.

• Journal of Korean Orthopaedic Sports Medicine
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• v.8 no.1
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• pp.13-18
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• 2009

Purpose: To report the clinical results of patients treated for a rupture of the distal tendon of biceps brachii Materials and Methods: Between February 1987 and March 2004, we treated 16 patients with a rupture of the distal tendon of biceps brachii. 9 of 16 patients underwent surgical treatment. All cases were male, median age was 26.3(range, 16-48) years. The mean interval between injury and surgery was 4.7 days (range, 1~36 days). Operative correction was performed anatomically, using the two-incision technique(3 cases) or one-incision technique(6 cases). Clinical outcomes were evaluated one year after operation by assessing the review about the physical examination finding and radiologic findings with surgical findings, range of motion, muscle strength, subjective satisfaction, activity and return to previous occupation. and via telephone interview in cases of conservative treatment. Results: In cases of surgical treatment, 85.8%, 86.3% of flexion-extension and supination-pronation motion than healthy side were measured respectively. 75% of flexion power than healthy side was measured. Eight of nine(89%) were very satisfied. Eightl of nine returned to original job. In cases of conservative treatment, 65% of flexion power than pre-injury state was reported. Four of seven were satisfied, two were dissatisfied, one was very dissatisfied. Three of seven returned to original job. Conclusion: Early anatomic reconstruction can restore more strength and endurance for supination and flexion range and power. Conservative management may be considered for partial injuries, but operative repair must be considered in complete rupture, athletes, patient with high activity.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.77-85
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• 2009

This study is aimed at providing information on injury prevention and skill improvement by inducing the accurate movements in exercise as well as understanding the principles of badminton drive movements. Movement displacement of racket head showed the similar patterns among those surveyed but, it seemed that slight differences resulted from external factors such as height, length of brachial and forearm and individual trend of swing locus. Regarding upper joint angle per phase, the angles of shoulder joint, elbow joint and wrist joint were closely associated in taking drive movements and they supported the segment order theory that power was conveyed from proximal into distal. It was shown that angular velocity of upper joint became larger in follow through movement after impact among all those surveyed, which meant the importance of follow through in racket sports such as badminton. In conclusion, this follow through movement acts as an important factor in racket sports in terms of pose stability maintenance, pose correction of movements and injury prevention of joints. In summary, when swings are made according to segment order theory, efficient movements can be taken.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1089-1097
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• 2002

In this paper, the novel shipboard Active Phased Array Antenna(APAA) system for maritime mobile satellite communications is introduced. The antenna uses novel technologies like wide range hybrid tracking, single antenna elements with both of Rx and Tx, asymmetrical array structure, interference isolation between Rx and Tx, and error correction method from frequency scan effect. The antenna has single aperture for both of Rx and Tx with 32 $\times$ 4 two-dimensional array. The antenna has two beams. Its frequencies are 7.25 ~ 7.75 GHz for Rx and 7.9 ~ 8.4 GHz for Tx. The antenna gains are 35.4 dBi for Rx and 35.7 dBi for Tx, those are 54 % of efficiency. The electrically steering ranges are $\pm$35$^{\circ}$ of elevation direction and $\pm$4$^{\circ}$ of azimuth direction. The mechanical control ranges at hybrid tracking capability are continuous 360$^{\circ}$ of azimuth direction and $\pm$10$^{\circ}$ of elevation direction. The antenna has 2.2$^{\circ}$ of 3 dB beamwidth, -14 dB of sidelobe level, and 21 dB of cross-pol suppression. The antenna performance was measured by near field measurement set. Its system performance was tested on the ship motion simulator and with the satellite transponder simulator. The test result showed that its tracking error was within -3 dB from its peak gain under motion condition. The antenna system was tested by real modulated Direct Broadcasting Satellite(DBS) signals to check its communication processing function.

• Physical Therapy Korea
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• v.25 no.3
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• pp.19-26
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• 2018

Background: Genu varum is also known as bow leg. It is a deformity wherein there is lateral bowing of the legs at the knee. it does give rise to pain, and persistent bowing can often give rise to discomfort in knees, hips and ankles. Objects: This study investigated the effect of narrow squats on the knee joint during a gait and distance between the knees of person with genu varum. Methods: This study analyzed 23 patient with genu varum that grade III, 12 narrow squat group and 11 genenal squat group in motion analysis laboratory. The subjects of experiment took gait before and after intervention, the range of joint motion, moment of knee joint adduction, power, distance of the knees were measured. And in order to make an analysis between groups, an paiered t-test and independent t-test was carried out. For statistical significance testing, it was decided that significance level ${\alpha}$ be .05. Results: It was shown that the group of narrow squat exercise significantly decreased in distance of knees (p<.05),In moment of adduction of knee joint, it was shown to significantly decrease in two groups (p<.05), was significantly decreased in adduction, abduction, and rotation (p<.05). In relation of peak-knee adduction moment and valgus angle, there was significant decrease in narrow squat group (p<.05). Conclusion: When the above result of study were examined, a narrow squat exercise given to the genu varum patients significantly decreased the distance between the knees, range of knee adduction and abduction, knee adduction moment, knee power. And stability gains through the decrease of excursion of knee medial part be effective for the correction of genu varum deformation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.529-538
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• 2016

The simplified plate theory is presented for static and free vibration analysis of power-law(P) and sigmoid(S) Functionally Graded Materials(FGM) plates. This theory considers the parabolic distribution of the transverse shear stress, and satisfies the condition that requires the transverse shear stress to be zero on the upper and lower surfaces of the plate, without the shear correction factor. The simplified plate theory uses only four unknown variables and shares strong similarities with classical plate theory(CPT) in many aspects such as stress-resultant expressions, equation of motion and boundary conditions. The material properties of the plate are assumed to vary according to the power-law and sigmoid distributions of the volume fractions of the constituents. The Hamilton's principle is used to derive the equations of motion and Winkler-Pasternak elastic foundation model is employed. The results of static and dynamic responses for a simply supported FGM plate are calculated and a comparative analysis is carried out. The results of the comparative analysis with the solutions of references show relevant and accurate results for static and free vibration problems of FGM plates. Analytical solutions for the static and free vibration problems are presented so as to reveal the effects of the power law index, elastic foundation parameter, and side-to-thickness ratio.

• 한국체육학회지인문사회과학편
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• v.55 no.6
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• pp.749-757
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• 2016

The purpose of this study was to investigate the effect of stability on one leg standing posture in yoga practice. Thirteen women college student who have never done yoga participated in this study. In order to collect data before and after yoga practicing for two years, we were used 3D motion capture system and electromyography. The results were as follows. First, ranges of motions for Y axis of left knee joint and X axis of right ankle joint were significantly different in dancer posture(p<.05), and then X axis of right ankle and Y axis of left ankle joint were significantly different in tree posture of pre and post training. Second, the planar alignment angle of trunk-pelvis was not significant difference in dancer and tree posture. Third, CoM-distances of Y, Z directions were significant difference in the tree posture(p<.05). Fourth, Muscle activities of both rectus abdominis, erector spinae and left quadriceps were significant difference in tree posture(p<.05). These findings suggested that yoga training played important roles in stable postures as results of decreasing rotation ankle joint and movement of CoM and enforcing core muscles. This study provides evidence for effectiveness of the stability on standing posture and can get a great effect on posture correction by means of yoga training. Hereafter, study on alignment angle, which is a measurement of postural stabilization will be needed by future yoga training.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.2
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• pp.31-39
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• 2003

The MPEG-2 source coding algorithm is very sensitive to transmission errors due to using of variable-length coding. When the compressed data are transmitted, transmission errors are generated and error correction scheme is not able to be corrected well them. In the decoder error concealment (EC) techniques must be used to conceal errors and it is able to minimize degradation of video quality. The proposed algorithm is method to conceal successive macroblock errors of I-frame and utilize temporal information of B-frame and spatial information of P-frame In the previous GOP which is temporally the nearest location to I-frame. This method can improve motion distortion and blurring by temporal and spatial errors which cause at existing error concealment techniques. In network where the violent transmission errors occur, we can conceal more efficiently severe slice errors. This algorithm is Peformed in MPEG-2 video codec and Prove that we can conceal efficiently slice errors of I-frame compared with other approaches by simulations.

• Journal of the Korean Solar Energy Society
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• v.30 no.3
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• pp.98-107
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• 2010

This paper introduces step by step procedures for the design, fabrication and operation of a solar tracking system. The system presented in this study consists of motion controllers, motor drives, step-motors, feedback devices and other accessories to support its functional stability. CdS sensors are used to constantly generate feedback signals to the controller, which assures a high-precision solar tracking even under adverse conditions. It enables instant correction if the system goes off track by strong winds causing gear backlash. A parabolic dish concentrator is mounted on the tracking system whose diameter was 30cm. The solar position data, in terms of azimuth and elevation, sunrise and sunset times were compared with those of the Astronomical Applications Department of the U.S. Naval Observatory. The results presented here clearly demonstrate the high-accuracy of the present system in solar tracking, which are applicable to many existing solar systems.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.4
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• pp.255-260
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• 1991

A voltage measuring system specified for the voltage fluctuation of the Pusan-Hamada submarine cable is developed by adding circuits of differential amplification and analog-to-digital conversion to a microprocessor-based data logger with a data modem. This system is charaterized by its small size. no power failure. fully unmanned operation. and precise instrumental drift correction. In addition to the cable voltage and current it measures an ambient temperature and a mercury cell voltage in order to calibrate temperature effect and check its long-term stability. The data acquired by this system show that the voltage signal. comprising fast random noises with a constant width of about 0.2V. fluctuates within a range of about 1V and the fluctuation frequency is similar to that of tidal motion. The source voltage of power feeding equipment (PFE) for the cable system seems to be affected when the room temperature changes rapidly.