• Journal of Digital Convergence
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• v.17 no.3
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• pp.463-471
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• 2019

The purpose of this study was to investigate the effect of muscle imbalance on motion of back squat. The isokinetic muscle strength of the 8 subjects was recorded for the knee flexion/extension by the cybex 770 dynamometer. Each subject performed 3 back squats with the long barbell with an intensity of 25% body weight(BW), 50%BW, 100%BW, 125%BW. During the back squat through the recorded kinematic data the subjects' maximum flexion and extension knee angle, center of mass displacement and V-COP were calculated for evaluation of the stability of the movement. For the statistical analysis independent t-test was used. Knee flexion angle and COM displacement are dominated by the reciprocal muscle ratio. V-COP factor was dominated by bilateral extension deficit. Based on the results we can know that as the intensity of the squat increased to a level control was difficult because the muscles' imbalance influenced the movement.

• The Journal of the Convergence on Culture Technology
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• v.5 no.2
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• pp.337-344
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• 2019

The purpose of this study men and women 20 to 30 of 16 patients wearing thick insoles 5cm before and after squat exercise based on the angle of the knee joint(0-, 60-, 90-degree) was to observe the muscle activities. For this through the analysis of the rectus femoris EMG, vatus medialis vatus lateralis, tibialis anterior, gastrocnemius MVIC were quantified using. The results following results were obtained. After wearing the thick insole standing position(0') had increased EMG activity of vastus lateralis muscle, the knee angle is rectus femoris, vatus medialis, vastus lateralis, tibialis anterior, gastrocnemius muscles were increased muscle activity. thick insole of the ankle joint, causing plantar flexion forward weight distritbution by focusing is normally the body would lead to an array. When an array of everyday life, these abnormalities increases energy consumption, and muscle fatigue, increase will cause an imbalance in the muscles. Therefore, wearing thick insoles by changing the activity of the muscles may cause knee pain.

• International journal of advanced smart convergence
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• v.9 no.4
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• pp.26-33
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• 2020

This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

• Journal of Digital Convergence
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• v.20 no.2
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• pp.407-413
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• 2022

This study conducted empirical analysis through user experience and questionnaire to find out whether the technical and contextual elements of the 'COVID-19 SABER' VR game produced and developed through initial research affect the improvement of the user's visual immersion. As a result first, the hypotheses regarding the resolution, viewing angle, effect, and design quality of the technical elements were accepted, but the hypotheses regarding the frame rate and the brightness of the lighting were rejected. Next, as for the hypothesis of the contextual elements, the hypothesis about background, directing, color and texture, interest and fun was adopted, and the hypothesis about storytelling was rejected. In summary, it was concluded that in order to increase the visual immersion of VR games, technical elements resolution, viewing angle, effect, design quality, contextual elements background, directing, color and texture, interest and fun must be designed and produced. The results of this study are expected to serve as basic data for the production and development of VR games that can induce and improve user's visual immersion in the future.

• Physical Therapy Korea
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• v.30 no.3
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• pp.174-183
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• 2023

Background: Office workers experience neck or back pain due to poor posture, such as flexed head and forward head posture, during long-term sedentary work. Posture correction is used to reduce pain caused by poor posture and ensures proper alignment of the body. Several assistive devices have been developed to assist in maintaining an ideal posture; however, there are limitations in practical use due to vast size, unproven long-term effects or inconsistency of maintaining posture alignment. We developed a headphone and necklace posture correction system (HANPCS) for posture correction using an inertial measurement unit (IMU) sensor that provides visual or auditory feedback. Objects: To demonstrate the test-retest reliability and concurrent validity of neck and upper trunk flexion measurements using a HANPCS, compared with a three-dimensional motion analysis system (3DMAS). Methods: Twenty-nine participants were included in this study. The HANPCS was applied to each participant. The angle for each action was measured simultaneously using the HANPCS and 3DMAS. The data were analyzed using the intraclass correlation coefficient (ICC) = [3,3] with 95% confidence intervals (CIs). Results: The angular measurements of the HANPCS for neck and upper trunk flexions showed high intra- (ICC = 0.954-0.971) and inter-day (ICC = 0.865-0.937) values, standard error of measurement (SEM) values (1.05°-2.04°), and minimal detectable change (MDC) values (2.92°-5.65°). Also, the angular measurements between the HANPCS and 3DMAS had excellent ICC values (> 0.90) for all sessions, which indicates high concurrent validity. Conclusion: Our study demonstrates that the HANPCS is as accurate in measuring angle as the gold standard, 3DMAS. Therefore, the HANPCS is reliable and valid because of its angular measurement reliability and validity.

• Physical Therapy Korea
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• v.30 no.4
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• pp.261-267
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• 2023

Forward head posture (FHP) is a musculoskeletal disorder that causes neck pain. Several exercise interventions have been used in South Korea to improve craniovertebral angle (CVA) and relieve neck pain. There has been no domestic literature review study over the past 5 years that has investigated trends and effects of exercise intervention methods for CVA with neck pain. This domestic literature review aimed to evaluate the trends and effects of exercise interventions on CVA and neck pain in persons with FHP. A review of domestic literature published in Korean or English language between 2018 and 2022 was performed. Literature search was conducted on Google Scholar and Korea Citation Index by using the following keywords: "exercise," "exercise therapy," "exercise program," "forward head posture," and "neck pain." Ten studies were included in this review. All of the studies showed positive improvements after intervention programs that included exercises. Notably, four of these studies demonstrated significant differences in results between the experimental and control groups. Among the 10 studies, nine measured visual analogue scale or numerical rating scale scores and reported significant reductions in pain following interventions, including exercise programs. Five of these studies showed significant differences in results between the experimental and control groups. Furthermore, six studies that used neck disability index exhibited a significant decrease in symptoms after implementing intervention programs that included exercise, and significant differences in results were found between the experimental and control groups. This domestic literature review provides consistent evidence to support the application of various exercise intervention programs to improve CVA and relieve neck pain from FHP. Further studies are warranted to review the effects of various exercise interventions on FHP reported not only in domestic but also in international literature.

• Journal of Adhesion and Interface
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• v.16 no.2
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• pp.69-75
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• 2015

Stone board for the rock bed was needed to reduce weight using thin thickness and reinforced materials. In this work, stone/wood board for rock bed was studied. Stone and wood were attached to reduce total weight of stone for rock bed. For reinforcing wood heat treatment method was used to change surface and mechanical properties. Mechanical strength of heat treated wood increased more than neat condition. The optimum heat treatment condition was set on $100^{\circ}C$ under tensile, flexural loads whereas surface energy was also obtained by contact angle measurement. Optimum adhesive condition was to get the maximum adhesion between stone and wood. Lap shear test was performed for stone/wood board with different adhesives such as amine type epoxy, polyurethane, chloro-rubber and vinyl chloride acetate type. Fracture surface of lap shear test was shown at wood fracture part on stone using amine type epoxy adhesive. It was found that for high adhesion between stone and wood the optimum adhesive was epoxy type for the rock bed.

• Journal of Adhesion and Interface
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• v.17 no.1
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• pp.15-20
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• 2016

Fiber arrangement was important for fiber reinforced thermoplastic composites using injection fabrication. In this work, fiber arrangement in CF/PP was investigated to use electrical resistance (ER) method during injection times. There were 3 types of injection products of CF/PP with different ER change ratio by fiber arrangement. High ER change ratio case of injection CF/PP products had better increased tensile strength. This reason was due to the fiber arrangement of CF/PP by injection. Fractured surface and contact angle of CF/PP products were used to evaluate for injection product quality. Uniform fiber arrangement of CF/PP by injection type exhibited the uniform heat condition of melted CF/PP. Steady thermal transfer effect occurred from melted CF/PP to steel injection mold. Steady thermal transfer effect of CF/PP was transmitted to high ER change ratio of mold. Ultimately, good condition CF/PP product by injection molding method could be predicted by using ER method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.541-547
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• 2017

Climate change has become the main cause of the exacerbation in natural disasters. Social Overhead Capital(SOC) structure needs to be checked for displacement and crack periodically to prevent damage and the collapse caused by natural disaster and ensure the safety. For efficient structure maintenance, the optical image technology is applied to the Structure Health Monitoring(SHM). However, optical image is sensitive to environmental factors. So it is necessary to verify its validity. In this paper, the accuracy of estimating the vertical displacement was verified with respect to environmental condition such as natural light, measurement distance, and the number of image sheets. The result of experiments showed that the effect of natural light on accuracy of estimating vertical displacement was the greatest of all. The measurement angle which was affected by the change in measurement distance was also important to check the vertical displacement. These findings will be taken into account by applying appropriate environmental condition to minimize errors when the bridge was measured by camera. It will also enable the application of optical images to the SHM.

• Journal of the Korea Convergence Society
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• v.12 no.3
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• pp.165-176
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• 2021

Recently, interest in home training and changes in lifestyle are expanding the market in the healthcare field, and high value-added fashion products reflecting the dumbbell economy phenomenon are being released. This study had the following objectives: to investigate the possibility of developing a fashion item that can be applied to the dumbbell economy phenomenon; to develop the UI/UX of a smartphone application for beginners who wish to work out their upper and lower bodies regardless of time and space; and to create a wearable customized smart athleisure fashion device. First, the study identified factors related to exercise methods, breathing techniques, and range of exercises for beginners by investigating the postures of workouts of the upper and lower bodies by angles. Based on the results, the study collected empirical data through a user needs analysis from muscle strengthening exercise experts to verify the significance of the study and use as fundamental data. Second, the study developed the UI/UX of a smartphone application with three different contents: counting, suggesting exercise postures, and providing exercise calendars. Further, the study analyzed necessary user-centered concepts and characteristics in terms of design and technology and developed a wearable customized smart athleisure fashion device based on the results.