• Physical Therapy Rehabilitation Science
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• v.5 no.3
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• pp.132-137
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• 2016

Objective: Eversion of the foot is created with internal rotation of the shank, and inversion of the foot is created with external rotation of the shank. The purpose of the study was to investigate the effect of continuous changes in the angle of the subtalar joint on lower extremity alignments. Design: Cross-sectional study. Methods: Seventeen healthy young adult subjects recruited. The subjects were asked to stand up in a natural standing position on a footplate with eye open and equal weight on each foot for 10s in two different conditions: The right subtalar joint was everted continuously $0^{\circ}-20^{\circ}$ and in separate segments of $0^{\circ}$, $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$. The averages of three trials were used. The observation of the changes in the lower extremity was performed with the use of 3-dimensional motion analysis. For data analysis, the SPSS 18.0 software using paired t-test and repeated measures analysis of variance (ANOVA) was applied. Results: The angle was significantly increased at the horizontal rotation angle of the shank, thigh, and ankle without anterior rotation of the pelvis (p<0.05). The maximum horizontal rotation angle at the thigh on $20^{\circ}$ was $-4.52^{\circ}$ in static, and $-3.10^{\circ}$ in the dynamic conditions compared to $0^{\circ}$. Conclusions: Increased unilateral foot pronation, thigh, shank, ankle horizontal rotation variance was significantly effective. The observation of the changes in foot abduction with the use of a 3-dimensional motion analysis augmented in predicting the angle values of each segment of the lower extremity. In further studies, a comparison of the right and left subtalar joints need to be investigated.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.5
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• pp.219-232
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• 2020

The slip-weakening model developed by Ohnaka and Yamashita is extended over the breakdown zone by equating the scaling relationships for the breakdown zone and the whole rupture area. For the extension, the study uses the relationship between rupture velocity and radiation efficiency, which was derived in the theory of linear elastic fracture mechanics, and the definition of f_max given in the specific barrier model proposed by Papageorgiou and Aki. The results clearly show that the extended scaling relationship is governed by the ratio of rupture velocity to S wave velocity, and the velocity ratio can be determined by the ratio of characteristic frequencies of a Fourier amplitude spectrum, which are corner frequency, f_c, and source-controlled cut-off frequency, f_max, or vice versa. The derived relationship is tested by using the characteristic frequencies extracted from previous studies of more than 130 shallow crustal events (focal depth less than 25 km, M_W 3.0~7.5) that occurred in Japan. Under the assumption of a dynamic similarity, the rupture velocity estimated from f_max/f_c and the modified integral timescale give quite similar scale-dependence of the rupture area to that given by Kanamori and Anderson. Also, the results for large earthquakes show good agreement to the values from a kinematic inversion in previous studies. The test results also indicate the unavailability of the spectral self-similarity proposed by Aki because of the scale-dependent rupture velocity and the rupture velocity-dependent f_max/f_c; however, the results do support the local similarity asserted by Ohnaka. It is also remarkable that the relationship between the rupture velocity and f_max/f_c is quite similar to Kolmogorov's hypothesis on a similarity in the theory of isotropic turbulence.

• Korean Journal of Applied Biomechanics
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• v.15 no.3
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• pp.1-7
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• 2005

Excessive pronation and impact force during running are related to various running injuries. To prevent these injuries, three type of running shoes are used, such as cushioning, stability, and motion control. Although there were may studies about the effect of midsole hardness on impact force, no study to investigate biomechanical effect of motion control running shoes. The purpose of this study was to determine biomechanical difference between cushioning and motion control shoes during treadmill running. Specifically, plantar and rearfoot motion, impact force and loading rate, and insole pressure distribution were quantified and compared. Twenty male healthy runners experienced at treadmill running participated in this study. When they ran on treadmill at 3.83 m/s. Kinematic data were collected using a Motion Analysis eight video camera system at 240 Hz. Impact force and pressure distribution data under the heel of right foot were collected with a Pedar pressure insole system with 26 sensors at 360 Hz. Mean value of ten consecutive steps was calculated for kinematics and kinetics. A dependent paired t-test was used to compare the running shoes effect (p=0.05). For most kinematics, motion control running shoes reduced the range of rearfoot motion compared to cushioning shoes. Runners wearing motion control shoe showed less eversion angle during standing less inversion angle at heel strike, and slower eversion velocity. For kinetics, cushioning shoes has the effect to reduce impact on foot obviously. Runners wearing cushioning shoes showed less impact force and loading rate, and less peak insole pressure. For both shoes, there was greater load on the medial part of heel compared to lateral part. For pressure distribution, runners with cushioning shoes showed lower, especially on the medial heel.

• Journal of the Korean earth science society
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• v.44 no.2
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• pp.119-134
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• 2023

The synoptic, thermodynamic, and dynamic characteristics of a snowfall event that occurred in the Yeongdong region on March 1-2, 2021, were investigated. Surface weather charts, ERA5 reanalysis data, rawinsonde data, GK-2A satellite data, and WISSDOM data were used for analysis. The snow depth, exceeding 10 cm, was observed at four weather stations during the analysis period. The maximum snow depth (37.4 cm) occurred at Bukgangneung. According to the analysis of the weather charts, old and dry air was trapped within relatively warm, humid air in the upper atmosphere over the East Sea and adjacent Yeongdong region. This caused unstable atmospheric conditions that led to developing convective clouds and snowfall over Bukgangneung. In particular, based on the thermodynamic and kinematic vertical analysis, we suggest that strong winds attributable to the vertical gradient of potential temperature in the low layer and the development of convective instability due to cold advection played a significant role in the occurrence of snowfall in the Yeongdong region. These results were confirmed from the vertical analysis of the rawinsonde data.

• Journal of the Korean earth science society
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• v.42 no.5
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• pp.479-495
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• 2021

This study investigates the synoptic (patterns of southern highs, northern lows, and lows rapidly developed by tropopause folding), thermodynamic, and kinematic characteristics of a strong wind that occurred in the Yeongdong region of South Korea on March 18-20, 2020. To do so, we analyzed data from an automatic weather station (AWS), weather charts, the European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis, rawinsonde, and windprofiler radars. The daily maximum instantaneous wind speed, exceeding 20 m s^-1, was observed at five weather stations during the analysis period. The strongest instantaneous wind speed (27.7 m s^-1) appeared in the Daegwallyeong area. According to the analysis of weather charts, along with the arrangement of the north-south low-pressure line, the isobars were moved to the Yeongdong area. It showed a sine wave shape, and a strong wind developed owing to the strong pressure gradient. On March 19, in the northern part of the Korean Peninsula, with a drop in atmospheric pressure of 19 hPa or more within one day, a continuous strong wind was developed by the synoptic structure of the developing polar low. In the adiabatic chart observed in Bukgangneung, the altitude of the inversion layer was located at an altitude of approximately 1-3 km above the mountaintop, along with the maximum wind speed. We confirmed that this is consistent with the results of the vertical wind field analysis of the rawinsonde and windprofiler data. In particular, based on the thermodynamic and kinematic vertical analyses, we suggest that strong winds due to the vertical gradient of potential temperature in the lower layer and the development of potential vorticity due to tropopause folding play a significant role in the occurrence of strong winds in the Yeongdong region.

• 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 Engineering Geology
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• v.32 no.4
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• pp.467-482
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• 2022

The Yeonghae basin is located at the northeastern part of the Yangsan fault (YSF; a potentially active fault). The study of the architecture of the Yeonghae basin is important to understand the activity of the Yangsan fault system (YSFS) as well as the basin formation mechanism and the activity of the YSFS. For this study, Digital Elevation Model (DEM) was used to highlight the marginal faults, and structural fieldwork was performed to understand the geometry of the intra-basinal structures and the nature of the bounding faults. DEM analysis reveals that the eastern margin is bounded by the northern extension of the YSF whereas the western margin is bounded by two curvilinear sub-parallel faults; Baekseokri fault (BSF) and Gakri fault (GF). The field data indicate that the YSF is striking in the N-S direction, steeply dipping to the east, and experienced both sinistral and dextral strike-slip movements. Both the BSF and GF are characterized dominantly by an oblique right-lateral strike-slip movement. The stress indicators show that the maximum horizontal compressional stress was in NNE to NE and NNW-SSE, which is consistent with right-lateral and left-lateral movements of the YSFS, respectively. The plotted structural data show that the NE-SW is the predominant direction of the structural elements. This indicates that the basin and marginal faults are mainly controlled by the right-lateral strike-slip movements of the YSFS. Based on the structural architecture of the Yeonghae basin, the study area represents a contractional zone rather than an extensional zone in the present time. We proposed two models to explain the opening and developing mechanism of the Yeonghae basin. The first model is that the basin developed as an extensional pull-apart basin during the left-lateral movement of the YSF, which has been reactivated by tectonic inversion. In the second model, the basin was developed as an extensional zone at a dilational quadrant of an old tip zone of the northern segment of the YSF during the right-lateral movement stage. Later on, the basin has undergone a shortening stage due to the closing of the East Sea. The second model is supported by the major trend of the collected structural data, indicating predominant right-lateral movement. This study enables us to classify the Yeonghae basin as an inverted strike-slip basin. Moreover, two opposite strike-slip movement senses along the eastern marginal fault indicate multiple deformation stages along the Yangsan fault system developed along the eastern margin of the Korean peninsula.