• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1395-1400
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• 2018

EO TGP(Electro-Optical Targeting Pod) is an optical tracking system which has various functions such as target tracking and image stabilization and LOS(Line of Sight) change. Especially, it is very important to move the LOS into a interest point for joystick command. When pilot move joystick in order to observe different scene, EO TGP gimbals should be operated properly. Generally, most EOTS just operate corresponding gimbal for joystick command. For example, if pilot input horizontal command in order to observe right hand screen, it just drive azimuth gimbal at any position. But in the screen, the image dosen't move in a horizontal direction because gimbal structure is Euler angle. And image rotation is occurred by elevation gimbal angle. So we need to move Pitch gimbal. So in the paper, we designed LOS moving algorithm which convert LOS command to gimbal velocity command to move LOS properly. We modeled a differential kinematic equation and then change the joystick command into velocity command of gimbals. This algorithm generate velocity command of each gimbal for same horizontal direction command. Finally, we verified performance through MATLAB/Simulink.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.687-693
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• 2011

Spring-mass models have been widely accepted to explain the basic dynamics of human gait. Researchers found that the leg stiffness increased with gait speed to increase energy efficiency. However, the difference of leg stiffness change with gait speed between the young and the elderly has not been verified yet. In this study, we calculated the lower limb stiffness of the elderly using walking model with an axial spring. Vertical stiffness was defined as the ratio of the vertical force change to the vertical displacement change. Seven young and eight elderly subjects participated to the test. The subjects walked on a 12 meter long, 1 meter wide walkway at four different gait speeds, ranging from their self-selected speed to maximum speed randomly. Kinetic and kinematic data were collected using three force plates and motion capture cameras, respectively. The vertical stiffness of the two groups increased as a function of walking speed. Maximum walking speed of the elderly was slower than that of the young, yet the walking speed correlated well with the optimal stiffness that maximizes propulsion energy in both groups. The results may imply that human may use apparent limb stiffness to optimize energy based on spring-like leg mechanics.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.339-347
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• 2014

The purpose of this study was to investigate joint torques of lower body segments on professional golfers. Three dimensional swing analysis was conducted on the seven subjects. Each subject was asked to swing with 45 inches of Callaway driver, where two force plates (9286AA, Kistler, Switzerland) were built, with his normal speed and tempo. The resultant joint moments of the lower extremities were computed using the kinematic variables of the segments, anthropometric measures and the ground reaction force data by inverse dynamics method. Based on the results of this study, the following conclusions were drawn; It was found that the left ankle joint torque at 3rd phase was increased toward extension on the X-axis and abduction on the Y-axis. The left knee joint torque was alternated from flexion to extension direction in order to lower down the body weight at the beginning of the downswing. The lumbar joint torque was alternated from flexion to extension in order to speed up the upper body rotation which could increase the club head speed ultimately.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.276-282
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• 2021

Objective: To investigate effects of Fibular Repositioning Taping (FRT) on lower extremity joint stiffness and angle during drop-landing. Method: Twenty-eight participants (14 healthy, 14 with chronic ankle instability [CAI]) performed drop-landings from a 60 cm box; three were performed prior to tape application and three were performed post-FRT. Three-dimensional kinematic and kinetic data were collected using an infrared optical camera system (Vicon Motion Systems Ltd. Oxford, UK) and force-plate (AMTI, Watertown, MA). Joint stiffness and sagittal angle of the ankle, knee, and hip were analyzed. Results: The hip [Healthy: p<.05; M ± SD: 29.43 ± 11.27 (pre), 33.04 ± 12.03 (post); CAI: p<.05; M ± SD: 31.45 ± 9.70 (pre), 32.29 ± 9.85 (post)] and knee [Healthy: p<.05; M ± SD: 53.44 ± 8.09 (pre), 55.13 ± 8.36 (post); CAI: p<.05; M ± SD: 53.12 ± 8.35 (pre), 55.55 ± 9.81 (post)] joints demonstrated significant increases in sagittal angle after FRT. A significant decrease in joint angle was found at the ankle [Healthy: p<.05; M ± SD: 56.10 ± 3.71 (pre), 54.09 ± 4.31 (post); CAI: p<.05; M ± SD: 52.80 ± 6.04 (pre), 49.86 ± 10.08 (post)]. A significant decrease in hip [Healthy: p<.05; M ± SD: 1549.16 ± 517.53 (pre), 1272.48 ± 646.73 (post); CAI: p<.05; M ± SD: 1300.42 ± 595.55 (pre), 1158.27 ± 550.58 (post)] and knee [Healthy: p<.05; M ± SD: 270.12 ± 54.07 (pre), 239.13 ± 64.70 (post); CAI: p<.05; M ± SD: 241.58 ± 93.48 (pre), 214.63 ± 101.00 (post)] joint stiffness was found post-FRT application, while no difference was found at the ankle [Healthy: p>.05; M ± SD: 57.29 ± 17.04 (pre), 59.37 ± 18.30 (post); CAI: p>.05; M ± SD: 69.15 ± 17.63 (pre), 77.24 ± 35.05 (post)]. Conclusion FRT application decreased joint angle at the ankle without altering ankle joint stiffness. In contrast, decreased joint stiffness and increased joint angle was found at the hip and knee following FRT. Thus, participants utilize an altered shock absorption mechanism during drop-landings following FRT. When compared to previous research, the joint kinematics and stiffness of the lower extremity appear to be different following FRT versus traditional ankle taping.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.677-685
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• 2011

In order to enhance public transportation and to maintain information credibility, improvement of accuracy regarding route and positional information of public transport is very significant. There have been a variety of methods using GPS to measure accuracy of location-based services. However, the researches of evaluation regarding kinematic position of linear objects measured by vehicle/kinematic GPS are still insufficient. That's why our paper aims to suggest method of evaluation accuracy on a real-time bus route surveyed by GPS by SBM(Single Buffering Method). To make it come true, we compared the findings on the static and dynamic positioning by using PP(Point Positioning), DGPS and GPS/INS integrated systems and analyzed the accuracy and error effects among them, focusing on Anyang city. Consequently, we can find out that in case of P.P. comparing positioning accuracy between RTK DGPS and GPS/INS, both of them have survey result within a margin of error of 5m. More importantly, we can evaluate positional accuracy of each GPS system based on the work provision of a public survey such as error for P.P.(14.5m, 18.1m), DGPS(16.9m, 18.5m), and GPS/INS(18.4m, 18.5m). We are expecting that proposed method in our paper can be utilized in a wide range of categories such as feasibility testing of GPS field survey and high accuracy of positioning for Bus Information System.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.171-179
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• 2017

Objective: The purpose of this study was to perform a kinematic and kinetic analysis of double-under jump rope technique according to skill level and sex. Method: Participants comprised a skilled group of 16 (9 males, 7 females), and an unskilled group of 16 with 6 months or less of experience (9 males, 7 females). Five consecutive double-under successes were regarded as 1 trial, and all participants were asked to complete 3 successful trials. The data for these 3 trials were averaged and analyzed after collecting the stable third jump in each trial. The variables used in the analysis included phase duration, total duration, flight time, vertical toe height, stance width, vertical center of mass displacement, and right lower limb ankle, knee, and hip joint angles in the sagittal plane during all events. Results: The skilled group had a shorter phase and total duration and a shorter flight time than the unskilled group. The vertical center of mass displacement and ankle dorsiflexion angle were significantly smaller in the skilled group. The male group had a shorter phase duration than the female group. The vertical toe height was greater, the stance width was smaller, and the ankle and hip flexion angles were smaller in the male group. Conclusion: Variables that can be used to distinguish between skill levels are phase and total duration, flight time, vertical center of mass displacement, and ankle dorsiflexion angle. Differences between sexes in double-under jump rope technique may be related to lower limb flexion angle control.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.269-279
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• 2011

This study was analyzed the characteristics on the stability of posture while conducting a through two and half rotation technic of pench$\acute{e}$ in rhythmic gymnastics. Two rhythmical gymnastics player(LKH and SSJ) who is a member of the national team were selected, and for obtain the kinematic and kinetic variables were used a ProReflex MCU 240 infrared camera(Qualisys, Sweden) and a Type9286A force platform(Kistler, Switzerland). The mechanical factors were computed by using Visual3D program and Matlab R2009a. During the landing and rotation phase the results showed following characteristics; 1) In medial-lateral and horizontal displacement of the support foot, LKH showed smaller movement than SSJ, but SSJ showed smaller movement than LKH in swing foot. LKH showed bigger movement in medial-lateral axis of COP and vertical axis of COG, but SSJ showed bigger movement in horizontal axis of COP and medial-lateral axis of COG. 2) SSJ showed bigger maximum horizontal and vertical velocity at P1 and P2 than LKH. 3) In the inclination angle of COP and COG, SSJ showed smaller change than LKH, but within medial-lateral tilt of the shoulder, LKH performed rotation motion in horizontal position than SSJ. There was no differences in each force components during rotation, but on landing phase, the results showed a characteristic that SSJ exerted bigger breaking force and vertical force than LKH.

• Journal of Biomedical Engineering Research
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• v.34 no.4
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• pp.212-217
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• 2013

Falling is one of the major public problems to the elderly, resulting in limitations of daily living activities. It can be induced by the functional loss of the balance ability and muscle strength in the elderly. It has been, however, not well investigated to suggest an effective methodology improving the balance ability and muscle strength for the prevention of the falling due to lack of information about the characteristics of the balance and muscle activations responded to the dynamic motions. The aim of the current study is, therefore, to identify the characteristics of the balance and muscle activations responded to the dynamic motions in Anterior-Posterior(AP) and Medial Lateral(ML) directions. For that, a motion capture system with eight infrared cameras, surface electromyogram system and Wii Fit system with a customized variable unstable base were used and kinematic and kinetic data obtained from the systems were analyzed for five healthy male($24.8{\pm}3.3years$, $177.4{\pm}2.0cm$, $73.9{\pm}12.9kg$, $23.5{\pm}4.0kg/m$). The results showed that the characteristics of the balance and muscle activations were differently responded to between the dynamic motions in Anterior-Posterior(AP) and Medial Lateral(ML) directions. These findings may indicate that customized dynamic motions should be applied to the training of the balance ability and muscle strength for the effective prevention of the falling. This study may be meaningful to providing basic information to establish a guideline improving effectively the balance ability and muscle strength.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.1-7
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• 2011

The purpose of this study was to investigate changes in kinetic and kinematic variables associated with an increase in upper body weight. Eighteen healthy male university students($175.96{\pm}4.19\;cm$, $70.79{\pm}8.26\;kg$) participated. Eight motion analysis cameras(Qualysis Oqus 500) and 2 force AMTI platforms(Advanced Mechanical Technologies Inc. OR6-7, US) were used to record motion and forces during the drop landing at a frequency of 120 Hz and 1200 Hz, respectively. QTM software(Qualisys Track Manager) was used to record the data, and the variables were analyzed with Visual 3D and Matlab 2009. For the drop landing, a box of $4{\times}2{\times}0.46\;m$ was constructed from wood. Knee and ankle maximum flexion angle, knee flexion angle, knee and ankle angle at landing, time for maximum ankle flexion after landing, and time for maximum knee flexion after landing were calculated. There was a significant change in the time for maximum and minimum ground force reaction and the time for maximum dorsal flexion after landing(p<.05) with increasing weight. There was no significant change for the hip, knee, and ankle ROM, whereas there was an increase in the angle ROM as the weight increased, in the order of ankle, knee, and hip ROM. This result shows that the ankle joint ROM increased with increasing weight for shock attenuation during the drop landing. There was a trend for greater ankle ROM than knee ROM, but there was no clear change in the ROM of the hip joint with increasing weight. In conclusion, this study shows the importance of ankle joint flexibility and strength for safe drop landing.

• Korean Journal of Agricultural Science
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• v.47 no.3
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• pp.657-665
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• 2020

The objective of this study was to investigate whether supplementation of pentoxifylline (PTX; phosphodiesterase inhibitor) to thawed boar semen improves the post-thaw motility of sperm and affects the efficiency of artificial insemination (AI) and further development. To determine the concentration of PTX for AI, frozen-thawed semen was incubated with 0, 5, 10, and 20 mM PTX in an extender freezing medium, respectively, after thawing. Kinematic properties of sperm were examined with a computer-assisted semen analysis (CASA) system. In addition, viability and mitochondrial activity were also tested by LIVE/DEAD and a MitoTracker kit. There were no significant differences in the kinetic parameters of thawed sperm between control and treatment groups, but overall assessment parameters such as motility and rapid progressive were higher in the 10 mM PTX group. In the viability and mitochondrial assay, there were no significant differences observed in the PTX treatment, compared to the control. For further analysis, artificial inseminations were performed using frozen semen and 10 mM PTX treated cryopreserved semen, respectively. There were no differences in pregnancy rates and fetus weights among the groups until 30 and 40 days, but litter size was reduced and relatively low-birth weight was observed in the PTX group. In summary, our findings suggest that enhancement of in vitro sperm quality or non-toxicity supplemented by PTX may have detrimental effects on fetus development.