• PNF and Movement
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• v.16 no.1
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• pp.151-159
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• 2018

Purpose: The aim of this study was to examine the activation of the contralateral upper and lower extremities and trunk muscle during ipsilateral upper extremity diagonal isokinetic exercise. Methods: Twenty-one healthy male subjects with no history of shoulder injury undertook ipsilateral diagonal isokinetic exercise at 60, 120, and $180^{\circ}/sec$, utilizing a standard Biodex protocol. Muscle activation amplitudes were measured in the upper trapezius, pectoralis major, biceps brachii, rectus abdominis, external oblique, rectus femoris, adductor longus, and biceps femoris muscles using electromyography. A one-way analysis of variance and paired t-tests were conducted, and the data were analyzed using SPSS, version 21.0. Results: The results revealed no statistically significant interaction between motion and angular velocity and no statistically significant contralateral muscle activation according to angular velocity (p>0.05). However, they revealed statistically significant contralateral muscle activation according to motion (p<0.05). Conclusion: These results suggest that the movements involved in contralateral upper extremity diagonal isokinetic exercise can enhance muscle strength in patients affected by stroke, fracture, burns, or arthritis.

• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.63-76
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• 2013

The purpose of this study was to investigate the effects of knee joint muscle fatigue and overweight on the angular displacement and moments of the lower limb joints during landing. Written informed consent forms, which were approved by the human subject research and review committee at Dong-A University, were provided to all subjects. The subjects who participated in this study were divided into 2 groups: a normal weight group and an overweight group, consisting of 15 young women each. The knee joint muscle fatigue during landing was found to increase the dynamic stability by minimizing the movements of the coronal and horizontal planes and maintaining a more neutral position to protect the knee. The effect of body weight during landing was better in the normal weight group than in the overweight group, with the lower limbs performing their shock-absorbing function in an efficient manner through increased sagittal movement. Therefore, accumulated fatigue of knee joint muscles or overweight may be highly correlated with the increase in the incidence of injury during landing after jumping, descending stairs, and downhill walking.

• The Journal of Korean Physical Therapy
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• v.28 no.3
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• pp.212-216
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• 2016

Purpose: The current study seeks to identify the relationship between torque values of the quadriceps and muscle activity during isometric and isokinetic exercises. Methods: The subjects of the study included 29 healthy individuals 17 men and 12 women) who took part in isometric and isokinetic exercises that utilized the quadriceps. The isometric exercises were performed three times each at 4 different angles (0, 30, 60, and 90 degrees). For the isokinetic exercises, concentric contraction and eccentric contraction were undertaken three times each at two angular velocities (30 and 60 degrees). Results: The muscle activity of the quadriceps during the isometric exercises showed significant differences at the 30, 60, and 90 degree angles. During the concentric contractions and eccentric contractions, muscle activity at the peak torque of the quadriceps indicated significant differences in vastus medialis, vastus lateralis, and rectus femoris at angular velocities of 30 and 60 degrees. Conclusion: When applied clinically based on the biomechanical analysis of the current study, it is possible to anticipate and selectively strengthen muscles with isometric and isokinetic exercises for not only healthy adults and professional athletes, but also for those who experience limited knee movement for long periods following knee surgeries.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.22-28
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• 2016

The monitoring and measurement of the motion of a human joint is very important in screening for degenerative brain diseases and tracking the rehabilitation process. Since there are various medical fields to benefit from angular motion measurement, the necessity for monitoring of human joint movement is increasing. In this study, the optical sensor is composed of a light emission unit with a red LED and an optical fiber, and a reception unit with an arrangement of three photodiodes. The angular detection range was widened with the use of multiple photodiodes and the developed algorithm. The result will be useful for designing an effective angular sensor with low cost and small size.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.904-914
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• 2011

The volumetric errors of CNC machining centers are determined by 21 errors, including 3 linear errors, 6 straightness errors, 3 perpendicular errors, 9 angular errors and non-rigid body errors of the machine tool. It is very time consuming and hard to measure all of these errors in which laser interferometer and other parts are used directly. Hence, as many as 21 separate setups and measurements are needed for the linear, straightness, angular and perpendicular errors. In case of the 5-axis machining centers, two more rotary tables are used. It can make 35 error sources of the movement. Therefore, the measured errors of multi movements of the 5-axis tables are very complicated, even if the relative measured errors are measured. This paper describes the methods, those analyze the error sources of the machining centers. Those are based on shifted diagonal measurements method (SDM), R-test and Double ball bar. In case, the angular errors of machine are small enough comparing with others, twelve errors including three linear position errors, six straightness errors and three perpendicular errors can be calculated by using SDM. To confirm the proposed method, SDM was applied to measuring 3 axes of machine tools and compared with directly measurement of each errors. In addition, the methods for measuring relative errors of multi-axis analysis methods using R-test and Double Ball Bar are introduced in this paper.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.47-55
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• 2011

The purpose of this study was to perform a kinematic analysis of Harai-goshi(hip throw) in superior female judo players. From our analysis, it appeared desirable for the player to shorten the duration of the technique for maximum results. It was also desirable for the player to draw the opponent backward while simultaneously maneuvering her close to her own body. A turning movement of the body toward the left side was found to be required for the technique, during which the player must lower the position of the center of gravity. During the subsequent angular change of the elbow, the player winds the elbow and, by moving the left shoulder, pulls the opponent toward her. The player lowers the body center by bending the left knee and letting the right knee extend, while turning the upper body and bending the hip joint. The player then draws the opponent in, contacts the opponent closely, turns, and stretches the right knee and hip joint rapidly and concisely, completing the move; it was also found to be desirable for the angular velocity to be increased for maximum efficacy.

• The korean journal of orthodontics
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• v.46 no.5
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• pp.280-289
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• 2016

Objective: The aim of this study was to analyze tooth movement and arch width changes in maxillary dentition following nonextraction treatment with orthodontic mini-implant (OMI) anchorage in Class II division 1 malocclusions. Methods: Seventeen adult patients diagnosed with Angle's Class II division 1 malocclusion were treated by nonextraction with OMIs as anchorage for distalization of whole maxillary dentition. Three-dimensional virtual maxillary models were superimposed with the best-fit method at the pretreatment and post-treatment stages. Linear, angular, and arch width variables were measured using Rapidform 2006 software, and analyzed by the paired t -test. Results: All maxillary teeth showed statistically significant movement posteriorly (p < 0.05). There were no significant changes in the vertical position of the maxillary teeth, except that the second molars were extruded (0.86 mm, p < 0.01). The maxillary first and second molars were rotated distal-in ($4.5^{\circ}$, p < 0.001; $3.0^{\circ}$, p < 0.05, respectively). The intersecond molar width increased slightly (0.1 mm, p > 0.05) and the intercanine, interfirst premolar, intersecond premolar, and interfirst molar widths increased significantly (2.2 mm, p < 0.01; 2.2 mm, p < 0.05; 1.9 mm, p < 0.01; 2.0 mm, p < 0.01; respectively). Conclusions: Nonextraction treatment with OMI anchorage for Class II division 1 malocclusions could retract the whole maxillary dentition to achieve a Class I canine and molar relationship without a change in the vertical position of the teeth; however, the second molars were significantly extruded. Simultaneously, the maxillary arch was shown to be expanded with distal-in rotation of the molars.

• Korean Journal of Applied Biomechanics
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• v.23 no.3
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• pp.209-218
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• 2013

This study was to perform the kinetic analysis of forward $1\frac{1}{2}$ somersault on the platform diving. Six men's diving players of the Korea national reserve athletes participated in this study. The variables were analyzed response time, velocity, center of mass (COM), angle, center of pressure (COP) and ground reaction force (GRF) of motion. For measure and analysis of this study, used to synchronized to 4 camcorder and 1 force plate, used to the Kwon3D XP (Ver. 4.0, Visol, Korea) and Kwon GRF (Ver. 2.0, Visol, Korea) for analyzed of variables. The results were as follows; Time factor were observed in maximum knee flexion depending on the extent of use at phase 1 of take-off to execute the somersault. This enabled the subject to secure the highest possible body position in space at the moment of jumping to execute the somersault and prepare for the entry into the water with more ease. Regarding the displacement of COM, all subjects showed rightward movement in the lateral displacement during technical execution. Changes in forward and downward movements were observed in the horizontal and vertical displacements, respectively. In terms of angular shift, the shoulder joint angle tended to decrease on average, and the elbow joints showed gradually increasing angles. This finding can be explained by the shift of the coordinate points of body segments around the rotational axis in order to execute the half-bending movement that can be implemented by pulling the lower limb segments toward the trunk using the upper limb segments. The hip joint angles gradually decreased; this accelerated the rotational movement by narrowing the distance to the trunk. Movement-specific shifts in the COP occurred in the front of and vertical directions. Regarding the changes in GRF, which is influenced by the strong compressive load exerted by the supporting feet, efficient aerial movements were executed through a vertical jump, with no energy lost to the lateral GRF.

• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.183-188
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• 2021

Objective: The purpose of this study was to develop a stretchable joint motion sensor that is based on silver nano-particle. Through this sensor, it can be utilized as an equipment for rehabilitation and analyze joint movement. Method: In this study, precursor solution was created, after that, nozel printer (Musashi, Image master 350PC) was used to print on a circuit board. Sourcemeter (Keithley, Keithley-2450) was used in order to evaluate changes of electric resistance as the sensor stretches. In addition, the sensor was attached on center of a knee joint to 2 male adults, and performed knee flexion-extension in order to evaluate accurate analysis; 3 infrared cameras (100 Hz, Motion Master 100, Visol Inc., Korea) were also used to analyze three dimensional movement. Descriptive statistics were suggested for comparing each accuracy of measurement variables of joint motions with the sensor and 3D motions. Results: The change of electric resistance of the sensor indicated multiple of 30 times from initial value in 50% of elongation and the value of electric resistance were distinctively classified by following 10%, 20%, 30%, 40% of elongation respectively. Through using the sensor and 3D camera to analyze movement variable, it showed a resistance of 99% in a knee joint extension, whereas, it indicated about 80% in flexion phase. Conclusion: In this research, the stretchable joint motion sensor was created based on silver nanoparticle that has high conductivity. If the sensor stretches, the distance between nanoparticles recede which lead gradual disconnection of an electric circuit and to have increment of electric resistance. Through evaluating angle of knee joints with observation of sensor's electric resistance, it showed similar a result and propensity from 3D motion analysis. However, unstable electric resistance of the stretchable sensor was observed when it stretches to maximum length, or went through numerous joint movements. Therefore, the sensor need complement that requires stability when it comes to measuring motions in any condition.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.448-455
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• 2019

This study aims to discover whether there are other factors, such as the ball position and address that will increase the percentage of holed putts from different angles of surface. In this study, we selected five male tour professional golfers that has been of 15 years or longer on the Korea Golf Association. As a research tool, after installing a video camera at an artificial site that's similar with the real green, and with the player's own putter, motion analysis was carried out using a Titleist V1x, which is commonly used by golfers. We use SPSS programs, significance level a=.05. According to the ball movement during the ball movement during the ball position putt by section, it is confirmed that the ball speed and angular velocity increase as the ball position changes from left to right. If the uphill putt, ball movement was found to be increased same change flat putt and There is no significance deviation. In this study, we investigate how the clubface and ball move during impact by varying the position of the address ball according to the slope during the ascent putt, which should increase the success rate among the various slopes. This study was conducted to present scientific data.