• 한국체육학회지인문사회과학편
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• v.53 no.2
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• pp.531-540
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• 2014

The purpose of this study was to investigate the differences between two inflatable kayak by recording performance related variables during the kayak forward stroke motion. A total of 5 elite high school kayak players were recruited to participate while their kinematics and muscle activations were recorded while performing inside their high school swimming pool. Boat velocity, boats swaying angle, the average angular velocity and were used to evaluate the boats performance. The player's trunk rotational range of motion, knee flexion-extension angle range of motion, maximum trunk rotation angle, the knee flexion-extension angular velocity, and the upper and lower limb muscle activations were calculated and analyzed for the player's efficiency evaluation. There were no significantly different variables for the player's kinematics and their muscle activations for the two conditions. The B kayak was significantly faster than the A kaya. In addition there were no significant differences between the remaining variables for the two kayaks. In conclusion, the B kayak was faster than the A kayak, but neither of the kayaks had an influence on the player's performance variables.

• Journal of the Korean Orthopaedic Association
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• v.56 no.1
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• pp.68-75
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• 2021

Purpose: The purpose of this study was to analyze the motion of the shoulder joint dynamically through a depth sensor-based motion analysis system for the normal group and patients group with shoulder disease and to report the results along with a review of the relevant literature. Materials and Methods: Seventy subjects participated in the study and were categorized as follows: 30 subjects in the normal group and 40 subjects in the group of patients with shoulder disease. The patients with shoulder disease were subdivided into the following four disease groups: adhesive capsulitis, impingement syndrome, rotator cuff tear, and cuff tear arthropathy. Repeating abduction and adduction three times, the angle over time was measured using a depth sensor-based motion analysis system. The maximum abduction angle (θ_max), the maximum abduction angular velocity (ω_max), the maximum adduction angular velocity (ω_min), and the abduction/adduction time ratio (t_abd/t_add) were calculated. The above parameters in the 30 subjects in the normal group and 40 subjects in the patients group were compared. In addition, the 30 subjects in the normal group and each subgroup (10 patients each) according to the four disease groups, giving a total of five groups, were compared. Results: Compared to the normal group, the maximum abduction angle (θ_max), the maximum abduction angular velocity (ω_max), and the maximum adduction angular velocity (ω_min) were lower, and abduction/adduction time ratio (t_abd/t_add) was higher in the patients with shoulder disease. A comparison of the subdivided disease groups revealed a lower maximum abduction angle (θ_max) and the maximum abduction angular velocity (ω_max) in the adhesive capsulitis and cuff tear arthropathy groups than the normal group. In addition, the abduction/adduction time ratio (t_abd/t_add) was higher in the adhesive capsulitis group, rotator cuff tear group, and cuff tear arthropathy group than in the normal group. Conclusion: Through an evaluation of the shoulder joint using the depth sensor-based motion analysis system, it was possible to measure the range of motion, and the dynamic motion parameter, such as angular velocity. These results show that accurate evaluations of the function of the shoulder joint and an in-depth understanding of shoulder diseases are possible.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.227-234
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• 2008

The purpose of this study was to investigate kinematic factors affecting scores of Olympic Round Game during follow through which was basic and important in archery. For this study, 8 male archers($20{\pm}1\;yrs$, $77{\pm}13kg$, $178{\pm}5\;cm$) of K university participated in the experiment. The seven infrared cameras (Qualisys MCU-240) were used to acquire raw data, and analyzed with Matlab6.5 for variables. The results were as follows: First, angular average velocity of shoulder joint affecting scores was a statistical significance (p=.65, p<.10), and the regression equation was y = - 0.0637 x + 17.074, and determinant coefficient $R^2$ = 0.874 respectively. Second, good records was acquired about $120^{\circ}$/sec. of angular average velocity of shoulder joint. Third, as records was lower and lower, a peak-pulse on angular average velocity of shoulder joint was great during follow through. In conclusion, the record was greater as angular average velocity of shoulder joint was smaller and smaller from $110^{\circ}$/sec. to $160^{\circ}$/sec. It is suggested that a lower angular average velocity of shoulder joint and no peak-pulse may obtain good scores during follow through.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.1
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• pp.70-77
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• 2005

The study was results obtained from the trial make of the hybrid GPS-electromagnetic(EM) compass which overcome shortcoming of GPS compass and EM compass. The results were summarized as follows: GPS compass detected the stable ship's heading at 0.1^{\circ}$ intervals with the turning angular velocity of less than 25^{\circ}$/sec in the experiment for the characteristics of turning angular velocity with stepmotor, but in case of over 25^{\circ}$/sec the compass did not detect it. On the contrary, the EM compass always indicated the ship's heading with no connection of the turning angular velocity, however the compass is low accuracy compared with GPS one owing to a compass error. The ship's headings by the hybrid GPS-EM compass were displayed at fixed point and moving by car; if the GPS compass work the headings were displayed by GPS compass, if not, the heading is provided stably by adding or subtracting of a compass error to the heading of EM compass. Also, each ship's heading was derived from not only the GPS compass but also the EM one by add or subtract of the compass errors, and then was worked covariance for the analogy. The results show that the ship's heading of two compasses has been verified the similarity to 95% confidence level.

• Membrane Journal
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• v.6 no.2
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• pp.86-95
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• 1996

Rotary disc ultrafiltration module(RDM) was developed for the separation of oil e$$\mu$sions. This module was devised to reduce the gel polarization phenomenon by decoupling the operation pressure and the surface velocity of solution in ultrafiltration(UF) processes. The rotary disc membrane consists of 3mm-thick ABS plate covered with UF membrane (UOP, U.S.A.). When the angular velocity($\omega$) was increased, the pure water flux was slightly decreased due to pressure drop caused by centrifugal force and slip flow at the surface of membrane. The pressure drop was proportional to the square of linear velocity(${\omega}r$). When the angular velocity was changed from 52.36rad/s to 2.62rad/s, the flux decline for 5% cutting oil in one-shaft RDM at $25^{\circ}C$ and 0.1MPa was 30.16%. In the lower concentrations, angular velocity tends to give less effect on the flux. Flux(J; $kg/m^{2} \cdot s$) in a rotating disc module is mainly a function of the bulk concentration($C_{B}$; %), the linear velocity(${\omega}r$; m/s) and the effective transmembrane pressure($\Delta P_{T}$ ; Pa). Using a modified resistance-in-series model, the flux data of cutting oil experiments were fitted to give the following equation.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.722-728
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• 2015

The demand for shipboard energy management is expected to gradually increase based on ship energy efficiency management plans (SEEMPs), which have been in use since January 1, 2013. Therefore, the fuel consumption of the main engine, which occupies the greatest portion of the energy used, along with elements related to the engine power, should be strictly monitored. There are many different methods for indicating the engine power. However, this study performed an experiment to monitor the status of a ship's engine power in real time using an encoder and a proximate switch, which are economical to purchase and easy to install. In the experiment, the angular velocity during one cycle of a two-stroke low-speed engine was measured, and the measured data were converted to the torque fluctuation. The angular velocity during an abnormal firing condition in the cylinder was also measured, and the torque fluctuation as a result of a misfire was considered. The results were compared with sea trial data to determine the reliability. In this study, the status of the engine power was determined using the torque fluctuation of the main engine in an operating ship.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.139-148
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• 2009

D. W. HAN. Y. R. AHN., N. J. LEE and E. J. LEE. Effects of Combined Restistance Training Program of Concentric and Eccentric Contraction Using Theraband on Shoulder Rotation Torque Max and Peak Power. Korean Joumal of Sport Biomechanics, Vol. 19, No. 1, pp. 139-148, 2009. The purpose of this study was to find out that combined concentric with eccentric resistance training program using Thera-Band was more effective than only concentric resistance training program on shoulder rotation torque max and peak power. 30 female students were randomly assigned to 3 equal group; concentric and eccentric, concentric, non training group. Subjects were tested in concentric and eccentric torque max and peak power of internal and external rotation using a CON-TERX isokinetic dynamometer. Subjects in training group participated in their regular five times a week for 4 weeks. After exercise, in concentric and eccentric training group, concentric and eccentric torque max, and peak power of internal rotator at 60 deg/sec were increased significantly. concentric peak power at 120 deg/sec were increased significantly. In concentric training group, only concentric peak power of internal rotator at 60 and 120 deg/sec was increased. In conclusion, we found out that combined concentric with eccentric resistance training program using Thera-Band was more effective than only concentric resistance training program on shoulder rotation torque max and peak power.

• Journal of the Korea Convergence Society
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• v.13 no.5
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• pp.287-294
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• 2022

This study was conducted to verify the effect of elastic-taping on the strength, power, and endurance of muscles. Elastic-taping is widely used in sports for preventing injuries due to flexion and extension of the knee joints. The participants of this study were 10 male college students with no abnormalities in knee flexion and extension movements. The function of flexors and extensors of the knee joint were assessed using the isokinetic muscle function measurement equipment at angular velocities of 60°/sec, 5 times; 180°/sec, 5 times; 240°/sec, 25 times before and after applying Kinesio taping. It was observed that the average power of muscles after application of Kinesio taping during knee extension on the right side was significantly increased at angular velocity of 180°/sec (p=.010). During knee flexion, the average power was significantly increased at the right angular velocity of 180° /sec after Kinesio taping was applied (p=.016). In addition, at an angular velocity of 240°/sec, both left (p=.002) and right (p=.002) sides showed significant increase in total work done. The application of Kinesio taping to the rectus femoris and biceps femoris showed a positive effect on improving muscle power and endurance during knee joint exercise.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.194.1-194.1
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• 2005

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.48-53
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• 1996

The role of the torquer in dynamically tuned gyroscope (DTG) is to erect the slanted rotor straight. This IBper presents the design method of the torquer. The torquer must satisfy the desired maximum angular velocity condition. The performance of magnet-residual flux density, maximum energy product, and so on-is limited by the material characteristics. So we should design the torquer with the limited condition that magnet performance is given. If the mechanical size of DTG is deter-mined, the dimension of the torquer is calculated and the space of the torquer becomes constant. Therefore, if we determine the diameter of the torquer coil, the number of coil turns is calculated automatically. Using these dimensions, we can calculate the torque and the scale factor. The maximum angular velocity is computed if we know the maximum current density. The analysis of the torquer was carried out by the 3-dimensional finite element method. The proposed algorithm of the torquer design was valid in comparison with the experimental data obtained from fabricated DTG.