• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.67-82
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• 2004

The purpose of this study was to evaluate the function and the safety of an additional weight shoe developed for the improvement of aerobic capacity, and to improve some problems found by subject's test for an additional weight shoe. The subjects employed for this study were 10 college students. 4 video cameras, AMTI force platform and Pedar insole pressure distribution measurement device were used to analyze foot motions. The results of the study were as follows: 1 The initial achilles tendon angle and initial rearfoot pronation angle of an additional weight shoe during walking were 183.7 deg and 2.33 deg, respectively, and smaller than a barefoot condition. Maximum achilles tendon angle and the angular displacement of achilles tendon angle were 185.35 deg and 4.21 deg respectively, and smaller than barefoot condition. Thus rearfoot stability variables were within the permission value for safety. 2. Maximal anterior posterior ground reaction force of additional weight shoe was appeared to be 1.01-1.2 B.W., and was bigger than a barefoot condition. The time to MAPGRF of an additional weight shoe was longer than a barefoot condition. Maximal vertical ground reaction force of additional weight shoe was appeared to be 2.3-2.7 B.W., and was bigger than a barefoot condition in propulsive force region. But A barefoot condition was bigger in braking force region. The time to MVGRF of an additional weight shoe was longer than a barefoot condition. 3. Regional peak pressure was bigger in medial region than in lateral region in contrast to conventional running shoes. The instant of regional peak pressure was M1-M2-M7-M4-M6-M5 -M3, and differed form conventional running shoes. Regional Impulse was shown to be abnormal patterns. There were no evidences that an additional weight shoe would have function and safety problems through the analysis of rearfoot control and ground reaction force during walking. However, There appeared to have small problem in pressure distribution. It was considered that it would be possible to redesign the inner geometry. This study could not find out safety on human body and exercise effects because of short term research period. Therefore long term study on subject's test would be necessary in the future study.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.839-847
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• 2020

The purpose of this study was to analyze the effects of ankle flexibility, gender, and Q-angle on the ankle joint injury factors during one leg drop landing. For this study, 16 males(age: 20.19±1.78 years, mass: 69.54±10.12 kg, height: 173.22±4.43 cm) and 16 females(age: 21.05±1.53 years, mass: 61.75±6.97 kg, height: 159.34±4.56 cm) in their 20's majoring in physical education using the right foot as their dominant feet were selected as subjects. First, an independent t-test of joint motion and joint moment according to the experience of ankle injury was conducted to determine the effect of physical characteristics on ankle joint injury during one leg drop landing(α = .05). Second, the variable that showed a significant difference through t-test was set as the dependent variable, and the ankle flexibility, gender difference, and Q-angle were designated as independent variables to use Multiple Linear Regression(α =. 05). As a result of this study, it was found that the group that experienced an ankle joint injury was found to use a landing strategy and technique through adduction of the ankle joint and internal rotation of the knee joint, unlike the group without an injury. It was also confirmed that this movement increases the extension moment of the ankle joint and decreases the extension moment of the hip joint. In particular, it was found that the dorsi flexion flexibility of the ankle affects the ankle and knee landing strategy, and the gender difference affects the ankle extension moment. Therefore, it was confirmed that physical characteristics factors affecting ankle joint injuries during one leg drop landing.

• Physical Therapy Korea
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• v.23 no.3
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• pp.21-28
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• 2016

Background: The toe-spread-out (TSO) exercise has been introduced as a strengthening exercise for the abductor hallucis muscle in subjects with hallux valgus. Visual biofeedback using ultrasound imaging during exercise, may increase the ability to selectively contract the abductor hallucis muscle, compared with exercise alone. Objects: The aim of this study was to investigate the effects of ultrasound imaging visual feedback during the TSO exercise with respect to its influence on the angle of the first metatarsophalangeal joint (1st MPJ) and the cross-sectional area (CSA) of the abductor hallucis muscle in subjects with hallux valgus. Methods: Twenty-five healthy young subjects with a mean average age of 22.5 years, and a standard deviation of 2.3 years, were recruited for this study. Hallux valgus was defined as an angles greater than $15^{\circ}$ angle of 1st MPJ. Goniometric measurement was used to determine the angle of 1st MPJ. In addition, an ultrasound system was used to collect the CSA of the abductor hallucis muscle in each foot. The angle of the 1st MPJ and CSA of the abductor hallucis were measured in three positions; the resting position, during TSO exercise, and during TSO exercise in conjunction with real-time ultrasound imaging feedback. All data analyzed using a repeated analysis of variance with Bonferroni correction in order to compare the dependent variables in all three positions. Statistical level of significance was set up as p<.05. Results: The angle of the 1st MPJ was noted to be significantly reduced and the CSA of the abductor hallucis to be significantly greater during TSO exercise used in conjunction with ultrasound imaging visual feedback, compared to when the values were recorded during TSO exercise alone (p<.05). Conclusion: Based on these findings, it can be concluded that the application of ultrasound imaging visual feedback during TSO exercise is more effective in contracting selectively the abductor hallucis than the use of exercise alone.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.265-277
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• 2019

The purpose of this study was to compare the effects of elastic band exercises and lunge on the knee Electromyography and Q-Angle in people with genu varum. The subjects of this study were healthy general people who had genu varum of 18 subjects. The subjects were randomly divided into two groups as a elastic band group (n=9, 6 males and 3 females, age: $22.55{\pm}2.05years$, height: $169.8{\pm}6.07cm$, weight: $66.44{\pm}9.83kg$) and a lunge group (n=9, 7 males and 2 females, age: $23.88{\pm}1.37years$, height: $173.66{\pm}6.72cm$, weight: $67.22{\pm}13.30kg$).The elastic band exercise and the lunge were performed every week, for four weeks. These results suggest that the Q-Angle of both knees showed differences before and after the intervention in elastic band group and lunge group. Also, The MVIC was no changes in both groups before and after the intervention except for the left foot in elastic band group and lunge group. As a result, the space distance of knees in both groups was significantly reduced. These result suggested that the elastic band exercise and lunge were effective ways in alleviating genu varum.

• Journal of Korean Foot and Ankle Society
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• v.9 no.2
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• pp.146-150
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• 2005

Purpose: We made a radiological comparison between $60^{\circ}$ distal Chevron osteotomy with short armed two parts and $40^{\circ}$ distal Chevron osteotomy with long armed one part performing operation in cases of hallux valgus angle of less than $40^{\circ}$, intermetatarsal angle of less than $15^{\circ}$. Materials and Methods: 12 cases with $60^{\circ}$ distal Chevron osteotomy and 12 cases with $40^{\circ}$ distal Chevron osteotomy were selected from October 2000 to March 2005. We have analysed the hallux valgus angle, 1-2 intermetatarsal angle, metatarsal length, distal metartarsal articular angle and angulation at osteotomy site on lateral view in each radiological films taken at preoperative, postoperative and 3 months after operation presuming bone union. All cases were women, both sides were 9 cases and average age was 52.3 years old. Results: Data taken at preoperative, postoperative and 3 months follow up films in $60^{\circ}$ distal Chevron osteotomy were as follows; the hallux valgus angles were $32.1^{\circ}$, $10.9^{\circ}$, $13.8^{\circ}$, the 1-2 intermetatarsal angles were $13.6^{\circ}$, $8.5^{\circ}$, $8.4^{\circ}$, the metatarsal length were 60.6 mm, 58.8 mm, 58 mm, the distal metartarsal articular angles were $13^{\circ}$, $6^{\circ}$, $6.6^{\circ}$ and 3 cases were over $3^{\circ}$ angulation at lateral view. In $40^{\circ}$ distal Chevron osteotomy, the hallux valgus angles were $34.5^{\circ}$, $11.6^{\circ}$, $15.3^{\circ}$, the 1-2 intermetatarsal angles were $12.7^{\circ}$, $8.2^{\circ}$, $7.8^{\circ}$, the metatarsal length were 59.2 mm, 56.9 mm, 55.9 mm, the distal metartarsal articular angles were $12^{\circ}$, $7.3^{\circ}$, $7.3^{\circ}$ and there were no case with angulation over $3^{\circ}$ at lateral view. Conclusion: In comparison between $60^{\circ}$ distal Chevron osteotomy and $40^{\circ}$ distal Chevron osteotomy measuring at postoperative and follow up, most of all data were similar, but 3 cases over $3^{\circ}$ angulation at lateral view happened in $60^{\circ}$ Chevron osteotomy. This result showed that $40^{\circ}$ distal Chevron osteotomy fixing with screws through long armed one part may have benefit than $60^{\circ}$ distal Chevron osteotomy fixing with K-wires through short armed two parts in making rigid fixation, even though there is a personal difference of technigue.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.345-359
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• 2002

The purpose of the study was to provide the fundamental data to instruct athletes through the analysis athletes' movement in javelin. Three athletes in the level of national representative were participated in this study. The study analyzed kinematic variables(lead foot and releasing javelin) through 3-D analysis and obtained the following results. 1. During withdrawal, it is important to maintain of running horizontal velocity. 2. It was showed that throng average height was $84{\pm}3.3%$ and javelin adequative degree, Among the athletes, $S_2$ who had the best record was released the javelin with the fast velocity, but throw the javelin with the less releasing velocity. 3. $S_2$ released after lead foot were completely landed and therefore it is no problem in a kinematic aspect. However, $S_1$ angle was too small. it caused increase of release velocity to be prevented. 4. $S_2$ showing the best result indicated shorter in duration time. Generally, the shorter duration time in release phase showed the longer release distance. Especially $S_1$ and $S_3$ showing the worse result indicated the longer duration time in preparatory phase, causing the breakup of force. Therefore to improve the record, it should be decreased the duration time in preparatory phase. 5. Compared with $S_1$ and $S_3$, $S_2$ showing the best record indicated the higher velocity in center of mass, trunk, upper arm, lower arm and hand That is the higher velocity of upper arm at release leaded the better velocity transfer from upper arm to following lower arm and hand, these action should be considered to be helpful of better record. According to the above conclusion, when the athletic leaders cauch athletes, they should focus on maintaining knee angle, upper body and hip angle in a previous stage of release and throwing angle, throwing height, throwing velocity in a release stage.

• Journal of Korean Foot and Ankle Society
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• v.8 no.1
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• pp.39-45
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• 2004

Purpose: The author modified the technique of Grice-Green, for managing flexible flat foot, with severe hindfoot valgus and possible dorsiflexion more than $15^{\circ}$. The purpose of this study was to evaluate the efficacy and results of this modified technique. Material and Methods: Total of 6 patients, 11 cases of pes planovalgus were operatively managed with Modified Grice-Green procedure from Nov. 1996 to April 2002. Total 11 cases in 6 patients were managed; 9 cases in 5 males, 2 cases in one female. The average age of the patients were 7.3 years (5.1-13.3 years). Average follow up period was 3.9 years (1.2-6.7 years). Patients were evaluated preoperatively and at last follow up radiologically and clinically. Radiologic evaluation were done by measuring the talocalcaneal and talo-$1^{st}$ metatarsal angles with the anteroposterior view; and by measuring the talo-$1^{st}$ metatarsal angles with the lateral view. The clinical outcome were rated by subjective and objective improvement level. Results: On follow up, 9 cases were complete satisfied, 2 cases were satisfied with minor reservation and no case had major reservations or dissatisfaction. Objective results were rated as excellent in 9 cases, good in 2 cases. Average preoperative talo-calcaneal and talo-$1^{st}$ metatarsal angles on anteroposterior radiograms were $34.4^{\circ}$ ($16-40^{\circ}$) and $32^{\circ}$ ($8-48^{\circ}$) respectively; which postoperatively on last follow up were $20^{\circ}$ ($3-37^{\circ}$) and $15.6^{\circ}$ ($3-34^{\circ}$) respectively. Average Preoperative talo-$1^{st}$ metatarsal angle on lateral radiogram was $18.4^{\circ}$ ($6-30^{\circ}$); which postoperatively on last follow up was $6.7^{\circ}$ ($-6-17^{\circ}$). Conclusion: Modified Grice-Green operative procedure is effective and satisfactory procedure for planovalgus deformity in children. but for more accurate results, more patients and further follow up period are needed.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.1-10
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• 2015

Objective : The purpose of this study was to find some kinetic variable's relationships between personal records and low records in female high jump. Methods : Collected data of the subjects(N=8, ages: $25.5{\pm}1.85$, height: $173{\pm}5.83$, mass: $54.75{\pm}6.36$ personal record: $1.71{\pm}0.04$, low record: $1.62{\pm}0.03$) were used for the last three strides and take-off phase. Five video cameras set in 30frames/s were used for recording. After digitizing motion, the Direct Linear Transformation(DLT) technique was employed to obtain 3-D position coordinates. The kinematic and kinetic factors of distance, velocity, angle, impulse, jerk variables were calculated. A paired t-test was applied for the difference of variables between personal records and lower records and for correlation with performances and variables. The significance level was accepted at p<.05. Results : There was no relationship between pattern of stride and performance. However, rate of change of velocity was related with cental of mass height(CMH) at peak point(PP). Knee, hip, backward lean, foot plant, approach and take off angle showed no difference between best record and low record. Vertical impulse momentum also showed no difference between performances. Conclusion : According to a t-test result, there were significant differences in CMH at PP and jerk at touch down between best record and low record.

• Physical Therapy Korea
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• v.11 no.4
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• pp.31-41
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• 2004

The purpose of this study was to examine the effect of the angle of a wedged insole on knee varus torque during walking. Fifteen healthy subjects were recruited. Knee varus torque was measured using three-dimensional motion analysis (Elite). Knee varus torque was normalized to gait cycle (0%: initial contact; 100%: ipsilateral initial contact) and stance phase (0%: initial contact; 100%: ipsilateral toe off). The average peaks of knee varus torque during the stance phase of the gait cycle according to the different insole angles (10 or 15 degrees) were compared using one-way ANOVA with repeated measures. The results showed that in the early stance phase, the average peak knee varus torque increased significantly for both the medial 10 and 15 degree wedged insole conditions and decreased significantly for both the lateral 10 and 15 degree wedged insole conditions as compared with no insole (p<.05). However, there were no significant differences between the 10 and 15 degree wedged insole conditions with either the medial or lateral wedged insole (p>.05). In the late stance phase, the average peak knee varus torque increased significantly for the medial 10 and 15 degree wedged insole conditions (p<.05), but not for the lateral 10 and 15 degree wedged insole conditions as compared with no insole (p>.05). We suggest that these results may be beneficial for manufacturing foot orthotic devices, such as wedged insoles, to control medial and lateral compartment forces in the knee varus-valgus deformity. Further studies of the effects of wedged insole angle on knee varus torque in patients with medial-lateral knee osteoarthritis are needed.

• Geomechanics and Engineering
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• v.15 no.2
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• pp.721-728
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• 2018

The surrounding rock mass contains cracks and joints which are distributed randomly around tunnels, and in the process of tunnel blasting excavation, radial cracks could also be induced in the surrounding rock mass. In order to clearly understand the impact of radial cracks on tunnel stability, tunnel model tests and finite element numerical analysis were implemented in this paper. Two kinds of materials: cement mortar and sandstone, were used to make tunnel models, which were loaded vertically and confined horizontally. The tunnel failure pattern was simulated by using RFPA2D code, and the Tresca stresses and the stress intensity factors were calculated by using ABAQUS code, which were applied to the analysis of tunnel model test results. The numerical results generally agree with the model test results, and the mode II stress intensity factors calculated by ABAQUS code can well explain the model test results. It can be seen that for tunnels with a radial crack emanating from three points on tunnel edge, i.e., the middle point between tunnel spandrel and its top with a dip angle $45^{\circ}$, the tunnel foot with a dip angle $127^{\circ}$, and the tunnel spandrel with $135^{\circ}$ with tunnel wall, the tunnel model strength is about a half of the regular tunnel model strength, and the corresponding tunnel stability decreases largely.