• Physical Therapy Korea
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• v.6 no.1
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• pp.23-34
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• 1999

The purposes of this study were to investigate biomechanical variables of the lumbar spine for women who enjoy recreational exercises regularly, and to determine the factors that influence these variables. These variables were determined by the X-ray pictures of the lumbar area of 80 housewives who visited the department of rehabilitation at the Y Hospital from October 1997 to March 1998. The sacral inclination angle, the sacrohorizontal angle, the lumbosacral joint angle, and the lumbar lordotic angle were analysed. The t-test, correlation analysis, and multiple regression analysis were used to determine the significant differences and relationships among variables. The result were as follows: 1) There was a significant difference in the sacral inclination angle (p<0.01), the sacrohorizontal angle (p<0.05) and the lumbar lordotic angle (p<0.05) between the bilateral and the unilateral exercise group. 2) With the sacral inclination angle, the sacrohorizontal angle, the lumbosacral joint angle and the lumbar lordotic angle, correlation was found between the sacral inclination angle and the sacrohorizontal angle (p<0.01), the sacral inclination angle and the lumbosacral joint angle (p<0.05), the sacral inclination angle and the lumbar lordotic angle (p<0.05), and the sacrohorizontal angle and the lumbosacral joint angle (p<0.01). 3) In the bilateral exercise group, the sacral inclination angle correlated with age (p<0.01). The sacrohorizontal angle correlated with age (p<0.01) and exercise time (p<0.01). The lumbar lordotic angle correlated with age (p<0.05) and exercise duration (p<0.05). In the unilateral exercise group, the sacral inclination angle correlated with age (p<0.01), while the sacrohorizontal angle correlated with age (p<0.01) and exercise duration (p<0.05). The lumbar lordotic angle correlated with age (p<0.05).

• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.205-213
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• 2021

Objective: The aim of this study was to analyze body stability Joint coordination pattern though as bending stiffness of shoes during stance phase of running. Method: 47 male subjects (Age: 26.33 ± 2.11 years, Height: 177.32 ± 4.31 cm, Weight: 65.8 ± 3.87 kg) participated in this study. All subjects tested wearing the same type of running shoes by classifying bending stiffness (A shoes: 3.2~4.1 N, B shoes: 9.25~10.53 N, C shoes: 20.22~21.59 N). They ran 10 m at 3.3 m/s (SD ±3%) speed, and the speed was monitored by installing a speedometer at 3 m intervals between force plate, and the measured data were analyzed five times. During running, ankle joint, MTP joint, coupling angle, inclination angle (anterior-posterior, medial-lateral) was collected and analyzed. Vector coding methods were used to calculate vector angle of 2 joint couples during running: MTP-Ankle joint frontal plane. All analyses were performed with SPSS 21.0 and for repeated measured ANOVA and Post-hoc was Bonferroni. Results: Results indicated that there was an interaction between three shoes and phases for MTP (Metatarsalphalangeal) joint angle (p = .045), the phases in the three shoes showed difference with heel strike~impact peak (p1) (p = .000), impact peak~active peak (p2) (p = .002), from active peak to half the distance to take-off until take-off (p4) (p = .032) except for active peak~from active peak to half the distance to take-off (p3) (p = .155). ML IA (medial-lateral inclination angle) for C shoes was increased than other shoes. The coupling angle of ankle angle and MTP joint showed that there was significantly difference of p2 (p = .005), p4 (p = .045), and the characteristics of C shoes were that single-joint pattern (ankle-phase, MTP-phase) was shown in each phase. Conclusion: In conclusion, by wearing high bending stiffness shoes, their body instability was increased during running.

• Korean Journal of Applied Biomechanics
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• v.24 no.1
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• pp.67-74
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• 2014

This study researched into the left-right inclination of the rear foot at the lower limb joints, knee joint angle, angular velocity of the knee joint, angular acceleration and the max. Based on the analysis of kinematics according to the changes in the height of step box (6, 8, 10 inches) during step aerobics of female college students majoring in physical education. The findings of this study are as follows: Then angle of the knee joint decreased as the height of the step box increased the min. Angle was measured right before the right foot was on the step box, and the angle tended to decrease as the step box get heightened. The left-right inclination of the rearfoot angle according to the height of step box increased as the height increased. In the 'pull-up' stage during which the weight was loaded on the right foot the angle increased, while in the right foot stepping stage during which the right foot was on the ground, the left-right inclination of the rearfoot angle increased as the height of the step box increased. The angular velocity of the knee joint according to the height of step box started increasing when the right foot initially stepped on the step box and during the initial stepping section, the angular velocity decreased as the height of step box increased. The changes in angular acceleration of the knee joint according to the height of step box increased as the height of step box increased.

• Geomechanics and Engineering
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• v.28 no.2
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• pp.181-195
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• 2022

Roughness and joint inclination angle are the important factors that affect the strength and deformation characteristics of jointed rock mass. In this paper, 3D printer has been employed to make molds firstly, and casting the jointed specimens with different joint roughness coefficient (JRC), and different joint inclination angle (α). Conventional triaxial compression tests were carried out on the jointed specimens, and the influence of JRC on the strength and deformation parameters was analyzed. At the same time, acoustic emission (AE) testing system has been adopted to reveal the AE characteristic of the jointed specimens in the process of triaxial compression. Finally, the morphological of the joint surface was observed by digital three-dimensional video microscopy system, and the relationship between the peak strength and JRC under different confining pressures has been discussed. The results indicate that the existence of joint results in a significant reduction in the strength of the joint specimen, JRC also has great influence on the morphology, quantity and spatial distribution characteristics of cracks. With the increase of JRC, the triaxial compressive strength increase, and the specimen will change from brittle failure to ductile failure.

• Journal of Oral Medicine and Pain
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• v.44 no.2
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• pp.59-64
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• 2019

Purpose: The aim of this study was to analyse and evaluate the morphology of the articular eminence of temporomandibular joint in young Korean adults using cone-beam computed tomography (CBCT). Methods: One hundred seventy-one subjects (59 males, 112 females) in the 20s were examined using CBCT. Width and height of articular eminence, top-roof line angle, best-fit line angle, joint space were measured. For the group comparisons, independent t-test was used with the level of significance established at $p{\leq}0.05$. Results: In asymptomatic young Korean adults, average eminence width was $9.49{\pm}1.62mm$ in males and $9.33{\pm}1.36mm$ in females. Average eminence height was $7.23{\pm}1.81mm$ in males and $6.82{\pm}1.31mm$ in females. Average eminence inclination of measured by top-roof line angle was $37.09^{\circ}{\pm}7.74^{\circ}$ in males and $36.12^{\circ}{\pm}5.65^{\circ}$ in females. Average eminence inclination measured by best-fit line angle was $50.79^{\circ}{\pm}11.49^{\circ}$ in males and $48.43^{\circ}{\pm}9.05^{\circ}$ in females. Average joint space was $3.03{\pm}0.67mm$ in males and $2.63{\pm}0.68mm$ in females. Conclusions: Increasing age did not affect the morphology of the articular eminence in asymptomatic young Korean adults. Males had slightly larger eminence width, height, top-roof line angle, best-fit line angle and joint space, but no statistical significance (p>0.05) was observed only in the joint space (p=0.001). There was no side-to-side difference in morphology (p>0.05).

• Geomechanics and Engineering
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• v.14 no.1
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• pp.29-42
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• 2018

This paper presents the results of an empirical study in which square rock-like blocks containing two parallel pre-existing rough non-persistent joints were subjected to uniaxial compression load. The main purpose of this study was to investigate uniaxial compressive strength and deformation modulus of jointed specimens. Response Surface Method (RSM) was utilized to design experiments and investigate the effect of four joint parameters, namely joint roughness coefficient (JRC), bridge length (L), bridge angle (${\gamma}$), and joint inclination (${\theta}$). The interaction of these parameters on the uniaxial compressive strength (UCS) and deformation modulus of the blocks was investigated as well. The results indicated that an increase in joint roughness coefficient, bridge length and bridge angle increased compressive strength and deformation modulus. Moreover, increasing joint inclination decreased the two mechanical properties. The concept of 'interlocking cracks' which are mixed mode (shear-tensile cracks) was introduced. This type of cracks can happen in higher level of JRC. Initiation and propagation of this type of cracks reduces mechanical properties of sample before reaching its peak strength. The results of the Response Surface Methodology showed that the mutual interaction of the joint parameters had a significant influence on the compressive strength and deformation modulus.

• Journal of the Korean GEO-environmental Society
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• v.16 no.2
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• pp.33-43
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• 2015

This paper investigated the magnitude and distribution of earth pressure on the support system in jointed rock mass by considering different earth pressure coefficients, rock types and joint inclination angles. The study mainly focused on the effect of the earth pressure coefficients on the earth pressure. Based on a physical model test (Son & Park, 2014), extended studies were conducted considering rock-structure interactions based on the discrete element method, which can consider the joints characteristics of rock mass. The results showed that the earth pressure was highly influenced by the earth pressure coefficients as well as the rock type and joint inclination angles. The effects of the earth pressure coefficients increased when the rock suffered more weathering and has no joint slide. The test results were also compared with Peck's earth pressure for soil ground, and clearly showed that the earth pressure in jointed rock mass can be greatly different from that in soil ground. This study indicated the earth pressure coefficients considering the rock types and joint inclination angles are important parameters influencing the magnitude and distribution of earth pressure, which should be considered when designing the support systems in jointed rock mass.

• Physical Therapy Korea
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• v.13 no.2
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• pp.16-25
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• 2006

The aim of this study was to investigate the kinematics of young adults during descent ramp climbing at different inclinations. Twenty-three subjects descended four steps at four different inclinations (level, $-8^{\circ}$, $-16^{\circ}$, $-24^{\circ}$). The 3-D kinematics were measured by a camera-based Falcon System. The data were analyzed using one-way ANOVA and the Student-Newman-Keuls test. The kinematics of descent ramp walking could be clearly distinguished from the kinematics of level walking. On a sagittal plane, the ankle joint was more plantar flexed at initial contact with $-16^{\circ}/-24^{\circ}$ inclination, was decreased in the toe off position with all inclinations (p<.001),and was decreased at maximum plantar flexion during the swing phase (p<.001). The knee joint was more flexed at initial contact with the $-24^{\circ}$ inclination (p<.001), was more flexed in the toe off position with all inclinations (p<.001), and was more flexed at minimum flexion during stance phase and at maximum flexion during swing phase with $-16^{\circ}$, $-24^{\circ}$ inclination (p<.001). The hip joint was more flexed in the toe off position with $-16^{\circ}$, $-24^{\circ}$ inclination and was deceased at maximum extension during stance phase with $-16^{\circ}$, $-24^{\circ}$ inclination (p<.05). In the frontal plane, the ankle joint was more everted at maximum eversion during stance phase with $-16^{\circ}/-24^{\circ}$ inclination (p<.01) and was decreased at maximum inversion during swing phase with $-16^{\circ}$, $-24^{\circ}$ inclination (p<.01). The knee joint was more increased at maximum varus during stance phase with $-16^{\circ}/-24^{\circ}$ inclination (p<.001). The hip joint was deceased at maximum adduction during stance phase with $-24^{\circ}$ inclination (p<.05). In a horizontal plane, only the knee joint was increased at maximum internal rotation during stance phase with $-24^{\circ}$ inclination (p<.05). In descent ramp walking, the different gait patterns occurred at an inclination of over $16^{\circ}$ on the descending ramp in the sagittal and frontal planes. These results suggest that there is a certain inclination angle or angular range where subjects do switch between level walking and descent ramp walking gait patterns.

• The Journal of Korean Physical Therapy
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• v.13 no.1
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• pp.127-137
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• 2001

Low back pain is significant problem in today's society, with lifetime incidence rate reported between 50% and 90%. Many factors associated with LBP are reported. The purpose of this studies were to be evaluated static standing posture aberrations in chronic LBP in comparison with healthy individuals. The samples including 80 subjects recruited to the following two groups:patients and control(normal) Questionnaires were completed by 40 LBP patients and 40 controls at the department of Physical Therapy, Saejong neurosurgical clinic in Taegu city from October 1, 1999 to March 30, 2000. The angle of lumbar lordosis was measured on lateral x-ray films with standing position. In LBP groups. the mean degree of lumbar lordosis, sacral inclination, and lumbosacral joint angle were 29.9 ${\pm}$ 9.3, 34.8 ${\pm}$ 8.2, and 12.7 ${\pm}$ 5.7 respectively. Control groups, the mean degree of lumbar lordosis, sacral inclination and lumbosacral joint angle were 35.3 ${\pm}$ 7.8, 34.9 ${\pm}$ 6.4 and 12.5 ${\pm}$ 4.3 respectively. there were significantly decreaseds in lumbar lordosis in Low back pain group. lumbar lordosis on the working posture had significant differences among groups(sitting position patients 31.4 ${\pm}$ 9.3, standing position patients 29.4 ${\pm}$ 9.3, sitting position control 35.0 ${\pm}$ 6.4, standing position control 35.5 ${\pm}$ 8.8, respectively) (p=0.034). sacral inclination on the working posture had differences among groups(sitting position patients 35.9 ${\pm}$ 8.7.standing position patients 33.6 ${\pm}$ 7.6, sitting position control 33.9 ${\pm}$ 5.9. standing position control 35.6 ${\pm}$ 6.8, respectively). lumbersacral joint angle on the working Posture had differences among groups(sitting position patients 12.0 ${\pm}$ 5.6, standing position patients 13.4 ${\pm}$ 5.9, sitting position control 11.2 ${\pm}$ 3.0. standing position control 13.4$^{\circ}$, respectively).

• Journal of the Korean Geotechnical Society
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• v.30 no.7
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• pp.41-53
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• 2014

This study examined the magnitude and distribution of the earth pressure on the support system in a jointed rock mass by considering different joint shear strength, rock type, and joint inclination angle. The study particularly focused on the effect of joint cohesive strength for a certain condition. Based on a physical model test (Son and Park, 2014), extended parametric studies were conducted considering rock-structure interactions based on the discrete element method, which can consider the rock and joint characteristics of rock mass. The results showed the earth pressure was strongly affected by the joint cohesive strength as well as the rock type and joint inclination angle. The study indicated that the effect of joint cohesive strength was particularly significant when a rock mass was under the condition of joint sliding. This paper investigates the magnitude of joint cohesive strength to prevent a joint sliding for each different condition. The test results were also compared with Peck's earth pressure, which has been frequently used for soil ground. The comparison indicated that the earth pressure in a jointed rock mass can be significantly different from that in soil ground. This study is expected to provide a better understanding of the earth pressure on the support system in a jointed rock mass.