• Tunnel and Underground Space
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• v.28 no.4
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• pp.343-357
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• 2018

Algorithm which can analyze the slope failure behavior utilizing the comprehensive information of the dense point of joint poles and the joint set orientations, both of which are obtained statistically, and the defect pattern of pole distribution has been developed. This method overcomes the potential incorrectness of the hemispheric projection method utilizing the joint set orientations only and also enhances the reliability of slope failure analysis. To this end a method capable of calculating the joint dispersion index directly from the joint pole distribution, instead of contour map, has been devised. The representative orientations for the slope failure analysis has been determined by considering the number and orientations of cone angle-dependent joint sets as well as the joint dispersion index. By engaging these representative orientations to the hemispheric projection analysis more reliable slope failure examination has been carried out. Sensitivity analysis for the potentially unstable slope of plane failure mode has been performed. Significance of joint strength index and the external seismic loading on the slope stability has been fully analyzed.

• Geomechanics and Engineering
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• v.13 no.4
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• pp.535-570
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• 2017

There are only few cases where cause and location of failure of a rock structure are limited to a single discontinuity. Usually several discontinuities of limited size interact and eventually form a combined shear plane where failure takes place. So, besides the discontinuities, the regions between adjacent discontinuities, which consist of strong rock and are called material or rock bridges, are of utmost importance for the shear strength of the compound failure plane. Shear behaviour of persistent and non-persistent joint are different from each other. Shear strength of rock mass containing non-persistent joints is highly affected by mechanical behavior and geometrical configuration of non-persistent joints located in a rock mass. Therefore investigation is essential to study the fundamental failures occurring in a rock bridge, for assessing anticipated and actual performances of the structures built on or in rock masses. The purpose of this review paper is to present techniques, progresses and the likely future development directions in experimental testing of non-persistent joint failure behaviour. Experimental results showed that the presence of rock bridges in not fully persistent natural discontinuity sets is a significant factor affecting the stability of rock structures. Compared with intact rocks, jointed rock masses are usually weaker, more deformable and highly anisotropic, depending upon the mechanical properties of each joint and the explicit joint positions. The joint spacing, joint persistency, number of rock joint, angle of rock joint, length of rock bridge, angle of rock bridge, normal load, scale effect and material mixture have important effect on the failure mechanism of a rock bridge.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.61-71
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• 2006

The purpose of this study was to compare kinematic characteristics on the limbs at 3 different walking speed during the energy and the normal walking. Eight subjects performed energy walking and normal walking at the slow speed(65 beats/min), the normal speed(115beats/min), the fast speed(160 beats/min). The 3-d angle was calculated by vector projected with least squares solution with three-dimensional cinematography(Motion Analysis corporation). The range of motion was calculated on the trunk, shoulder, elbow, hip, knee joint. The results showed that stride length was no difference of the two walking pattern. The duration of support phase was also no difference of the two walking pattern. The range of motion of shoulder joint significantly increased in the sagittal and frontal planes, and the range of motion of elbow joint significantly increased as the energy walking. The range of motion of hip joint had no significant difference in the any planes in changing of walking speed. But the most remarkable difference of the two walking patterns revealed at the trunk. The range of flexion/extension angle had significant increasing $2.36^{\circ}$ at normal speed, and the range of the right/left flexion angle had significant increasing below $4^{\circ}$ at the 3 walking speed, and The range of rotation angle had significant increasing $7.35^{\circ}$, $9.22^{\circ}$, respectively at the normal and slow speed. But there was no significant difference of range of motion at the hip and knee joints between energy walking and normal walking.

• Journal of Korean Physical Therapy Science
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• v.28 no.3
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• pp.42-52
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• 2021

Background: The purpose of this study was to investigate the effects of the severity and direction of lumbar disc herniation (LDH) on the facet joints and paraspinal muscles. Design: Cross-sectional design. Methods: The subjects were divided according to the diagnosis for severity of unilateral herniation of L4-L5 disc. The groups consisted of disc protrusion group (n=15), disc extrusion group (n=15), and no disc herniation group (n=15). The asymmetry and angle of facet joints and the cross-sectional area of paraspinal muscles were analyzed and compared using magnetic resonance imaging (MRI). Results: The results showed that the angle of facet tropism was larger in disc extrusion group than the disc protrusion group and the difference was found to be significant difference (p<0.01). In addition, when both left and right angles of patients with unilateral disc herniation were measured, the results showed larger facet joint angle in the herniated area of the disc extrusion group than in the disc protrusion group. When paraspinal muscles were measured according to the severity of disc herniation and the degree of facet joint asymmetry, there was no difference in paraspinal muscles between the disc protrusion and disc extrusion groups. Meanwhile, the multifidus muscle was smaller in the group with facet tropism than the group without facet tropism (p<0.03), while there were no significant differences in the erector spinae and psoas muscles. Conclusion: Progression of disc herniation resulted in increased facet joint tropism, increased angle of the facet joints in the direction of disc herniation, and decreased size of the multifidus muscle.

• The Journal of Korean Physical Therapy
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• v.24 no.4
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• pp.276-281
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• 2012

Purpose: The purpose of this study is to compare the kinematic motion of the first metatarsophalangeal (MTP) joint during an electrical stimulation of abductor hallucis (AbdH) muscle, between the normal group and the hallux valgus (HV) group. Methods: A total of twenty subjects (normal group=10 and HV group=10) participated in this study. The kinematic motions of first MTP joint was measured by using 3-dimensional motion analysis during an electrical stimulation in the sitting position. The intensity of an electrical stimulation was set to be tolerated in each subject, and the data of kinematic motions were collected in three trials of 5 seconds. An independent t-test was used to compare the angle of flexion and abduction of the first MTP joint and proximal phalanx in frontal plane, between the normal and HV groups. Results: Participants showed that the angle of flexion was significantly greater in the HV group ($13.12{\pm}10.61^{\circ}$), compared to that of the normal group ($10.17{\pm}2.31^{\circ}$); and the angle of abduction was significantly smaller in the HV group ($10.61{\pm}4.99^{\circ}$) than that of the normal group. Also, the angle of the proximal phalanx in frontal plane was significantly smaller, compared to the normal group ($53.42{\pm}10.70^{\circ}$) (p<0.05). Conclusion: These findings suggest that dysfunction of AbdH muscle is apparent in HV deformity and provide insight into potential risk factors for the development of HV deformity.

• Physical Therapy Korea
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• v.21 no.4
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• pp.49-55
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• 2014

Excessive lumbar flexion during sit-to-stand (STS) is a risk factor for lower back pain. Postural taping can prevent unwanted flexion of the lumbar spine. This study aimed to demonstrate the effect of taping the lower back on the lumbopelvic region and hip joint kinematics during STS. Sixteen healthy subjects participated. All subjects performed the STS with and without taping of the lower back. A three-dimensional motion analysis system was used to measure the kinematics of the lumbar spine, pelvis, and hip joint during STS. The angle of the peak lumbar flexion, pelvic anterior tilting, and hip flexion and angular displacement of the lumbar spine between starting position and maximal lumbar flexion were collected. Paired t-tests, or Wilcoxon's rank-sum test for non-parametric distribution, were used to assess differences in the measurements with and without taping. A p-value <.05 was taken to indicate a significant difference. Significant differences were observed in the angle of the peak lumbar flexion, pelvic anterior tilting, hip flexion and angular displacement of the lumbar spine (p<.05). Taping was associated with a significant decrease in the angle of peak lumbar flexion and angular displacement of the lumbar spine between the starting position and maximal lumbar spine flexion. In addition, the peak angle of pelvic anterior tilting and hip flexion were significantly increased with taping. The findings of this study suggest that taping the lower back can decrease excessive lumbar flexion, and increase the pelvic anterior tilting and hip flexion motion during STS.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.4
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• pp.619-625
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• 2013

PURPOSE: The purpose of this study was to determine the effects of muscle fatigue on knee joint position sense in the young, elderly adults, and stroke patients. METHODS: The subjects were recruited into three groups; young group(YG)(N=15), elderly group(EG)(N=15), and stroke group(SG)(N=15). Exercise-induced fatigue was achieved by repeated active exercise 60 times on an angle at 10 to 100 degrees of the knee joint with an angle speed of $120^{\circ}/s$, with three sets for 15 minutes. Evaluation was performed for determination of repositioning error using passive angle repositioning (PAR) and active angle repositioning (AAR). RESULT: Regarding the error score for the knee joint position sense in both the baseline and muscle fatigue, significant increases were observed between the YG and EG (p<.05), and between the EG and SG (p<.01), and between YG and SG (p<.05) in the PAR, YG and SG (p<.05) in the AAR. CONCLUSION: In particular, the results of this study indicate that management and intervention for elderly adults and stroke patients can result in improvement of proprioception.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.2
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• pp.109-114
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• 2018

PURPOSE: The purpose of this study conducted the experiment to check change of ability to grip depending on normal male adult's elbow flexion angle and the effect of kinesiology tape application. METHODS: Normal male adults who studies in H university where located in Kyoungbook state and did not have any factors like fracture, osteoarthritis, deformities and non-neurologic issue which might influence the result of this study were selected as subjects. Elbow of subjects were applied by 5cm wideness kinesiology tape and elbow's angle was selected by $0^{\circ}$, $45^{\circ}$, $90^{\circ}$, $135^{\circ}$ using Goniometer. The change of ability to grip depending on flexion was measured by an electronic dynamometer before and after taping. RESULTS: Before and after taping elbow joint, both ability to grip decrease in more flexion angle and $135^{\circ}$ of elbow flexion was lowest value, 299.84N. Using kinesiology tape, neutral position $0^{\circ}$ was the highest value, 352.26N. The lowest was 331.68N on $135^{\circ}$. According to verifying the change of ability to grip depending on elbow flexion and the change of ability to grip after taping with paired t-test, the result was p<.05, there was significant difference. CONCLUSION: Using electronic dynamometer and estimating the ability to grip after and before kinesiology tape, the ability to grip decrease in more elbow flexion. The ability to grip after using kinesiology tape was relatively higher than before taping.

• Korean Journal of Applied Biomechanics
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• v.34 no.2
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• pp.53-62
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• 2024

Objective: The purpose of this study was to analyze the differences in kinematic factors according to stretching treatment, myofascial release treatment, and static stretching treatment conditions during squat. Method: Twelve males with resistance training experience participated in this study. Participants performed squats without treatment (Pre-Test), and performed squats after treatment with the myofascial release technique (MRT) and static stretching (SS) on different days (post-test). Squat movements were captured using eight motion capture cameras (sampling rate: 250 Hz), and the peak joint angles of the ankle, knee, hip, and pelvis were calculated for each direction. One-way repeated ANOVA and Bonferroni post hoc analyses using SPSS 27 (IBM Corp. Armonk NY, USA) were used to compare the peak joint angle of the lower extremity joints and pelvis among the normal condition (squat without treatment), MRT condition (squat after MRT treatment) and SS condition (squat after static stretching). The statistical significance level was set at .05. Results: It was observed that the maximum ankle joint flexion angle during squats was statistically reduced under conditions of myofascial release and static stretching (p<.05), in comparison to the scenario where no stretching was performed. Furthermore, static stretching was found to enhance the maximum hip flexion angle during squat (p<.05), whereas the myofascial release stretching technique resulted in the minimal posterior pelvic tilt angle (p<.05). Conclusion: Employing myofascial release stretching as a preparatory exercise proved to be more efficacious in maintaining body stability throughout the execution of high-intensity squat movements by effectively managing the posterior tilt of the pelvis, as opposed to foregoing stretching or engaging in static stretching.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.361-367
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• 2016

Objective: The aim of this study was to compare three-dimensional kinematic changes of the lower extremity between the two different braking distances during snowplow in alpine skiing. Method: Six alpine ski instructors (age: $25.3{\pm}1.5yr$, height: $169.3{\pm}2.9cm$, weight: $66.2{\pm}5.9kg$, career: $4.2{\pm}2.9yr$) participated in this study. Each skier was asked to perform snowplow on the two different braking distances (2 and 4 m). Results: Snowplow and edging angles (p = .006 and p = .005), ankle adduction and inversion (p = .033 and p = .002), knee extension (p = .003), and hip abduction and internal rotation (p = .043 and p = .006) were significantly greater in the 2 m than in the 4 m braking distance. Conclusion: Based on our results, we suggest that skiers should make greater snowplow and edging angles on the shorter braking distance. In this situation, ankle joint adduction/inversion angle and hip joint internal-rotation make greater snowplow angle, and hip joint abduction make greater edging angle. In addition, greater knee joint extension angle may lead to more posteriorly positioned center of mass.