• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.141-147
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• 2015

Objective : This study aimed to understand how increased heart rates at the time of drop landing during a step test would affect biomechanical variables of the lower extremity limbs. Background : Ballet performers do more than 200 landings in a daily training. This training raises the heart rate and the fatigability of the lower extremity limbs. Ballet performance high heart rate can trigger lower extremity limb injury. Method : We instructed eight female ballet dancers with no instability in their ankle joints(mean ${\pm}$ SD: age, $20.7{\pm}0.7yr$; body mass index, $19.5{\pm}1.2kg/m^2$, career duration, $8.7{\pm}2.0yr$) to perform the drop landing under the following conditions: rest, 60% heart rate reserve (HRR) and 80% HRR. Results : First, the study confirmed that the increased heart rates of the female ballet dancers did not affect the working ranges of the knee joints during drop landing but only increased angular speeds, which was considered a negative shock-absorption strategy. Second, 80% HRR, which was increased through the step tests, led to severe fatigue among the female ballet dancers, which made them unable to perform a lower extremity limb-neutral position. Hence, their drop landing was unstable, with increased introversion and extroversion moments. Third, we observed that the increasing 80% HRR failed to help the dancers effectively control ground reaction forces but improved the muscular activities of the rectus femoris and vastus medialis oblique muscles. Fourth, the increasing heart rates were positively related to the muscular activities of the vastus medialis oblique and rectus femoris muscles, and the extroversion and introversion moments. Conclusion/Application : Our results prove that increased HRR during a step test negatively affects the biomechanical variables of the lower extremity limbs at the time of drop landing.

• The Journal of Korean Physical Therapy
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• v.25 no.2
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• pp.103-109
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• 2013

Purpose: This study was conducted in order to suggest an effective method of daily life movement training for stroke patients by comparison and analysis of the biomechanic characteristics of sitting up from a lying posture in stroke patients and healthy elderly participants. Methods: Fifteen stroke patients and 15 age-matched elderly participants were included in the study. The movement of sitting up from a lying posture was divided into three stages, and the differences in muscle activity in the sternocleidomastoid (SCM), rectus abdominis (RA), external oblique (EO), and rectus femoris (RF) during the movement were analyzed. Results: Subjects in the experimental group showed slower speed than those in the control group. In the neck joint, the change of angle in movement showed a larger decrease at all stages in the experimental group than in the control group; the movement also decreased in stages I and II in the upper trunk joint. The movement also showed a statistically significant decrease in stage II in the lower trunk, pelvic, and hip joints. The SCM showed higher activity in the control group than in the experimental group, showing a statistically significant difference; the RA showed high activity in the experimental group. The RF showed higher activity in the control group than in the experimental group, showing a statistically significant difference. Conclusion: From the results obtained above, increasing movements in the neck, pelvic, and hip joints and strengthening of lower body muscles are required in order to improve the ability for getting up from a lying posture in stroke patients.

• Journal of the Korea Safety Management & Science
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• v.11 no.2
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• pp.103-110
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• 2009

The purpose of this study is to suggest a proper tread of stairs using kinematic factors and moments of the lower-limb joints in the stair decent with the 3 different treads with boimechanical method in ergonomics. 9 subjects (body masses; $59.41{\pm}7.49$, $64.03{\pm}6.65$, $67.26:{\pm}7.58$, heights; $160.50{\pm}6.35$ ages; $31.22{\pm}2.99$; parity; $1.67{\pm}0.71$) participated in three experiments that were divided by physiological symptoms (the early (0-15 weeks), middle (16-27 weeks) and last (18-39 weeks). and they walked at self-selected pace on 4 staircases 3 trials. As extending the pregnancy period, cadence was shorter but cycle time were longer more and more. As extending treads of stair decent during pregnancy, speed, stride lengths and cycle time were increased. As extending the treads of stair decent, hip and ankle moments increased but knee moments decreased in sagittal plane. There were increasing or decreasing of moments by means of treads. These changes may account for relation between the treads of stair and moments in pregnant women. The main changes of pregnant women were joint moments and kinematic factors during pregnancy period because pregnancy makes them physical changes. It is possible that joints have connection with compensation each other to maximize stability and to control gait motion. In conclusion, we suggest that the tread of stair is longer than 26cm tread. and exercise programs to improve muscle activity were necessary where joint moments were small.

• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.249-256
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• 2015

Objective : The purposes of this study was to perform a kinematical analysis on age and walkway types in elderly women subjects. Method : Forty subjects participated in the experiment (A1 group - age: $67.30{\pm}1.49yrs$, height: $153.81{\pm}4.47cm$, weight: $61.80{\pm}5.24kg$, A2 group - age: $71.70{\pm}1.10yrs$, height: $152.01{\pm}2.84cm$, weight: $59.69{\pm}7.34kg$, A3 group - age: $76.80{\pm}0.98yrs$, height: $150.16{\pm}6.08cm$, weight: $57.27{\pm}6.42kg$, A4 group - age: $81.80{\pm}0.60yrs$, height: $152.18{\pm}4.77cm$, weight: $55.80{\pm}7.78kg$). The study method adopted was the 3D analysis with six cameras. Ground type were classifed as gait pattern on flat, ascent and descent ramp. For the statistical analysis, the SPSS 21.0 was used to perform Repeated measured Two-way ANOVA. Results : In velocity of CM, there was faster movement on flat ground. When it came to the velocity of right toe, there was no significance in early mid-swing of right foot, but A4 was the slowest in late mid-swing of right foot on flat ground. In joint angle in left foot strike, the left hip joint and knee joint were more flexed in descent ramp, In addition left and right ankle joints were more plantarflexed in descent ramp, and left ankle joint was more plantarflexed in the over 75 yrs age groups. Conclusion : The higher age group were more flexed in lower body joints during descent ramp.

• Tunnel and Underground Space
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• v.24 no.1
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• pp.55-66
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• 2014

In this study, a joint survey system was developed to efficiently analyze geometrical characteristics of joint structures in rock mass using photogrammetric technique. The system includes both hardware and software. The hardware consists of a high resolution image camera for photographing image of a surface of rock body, a direction controlling system for adjusting the attitude of camera, and a digital compass for measuring the rotation angle of camera. The software was also developed in order to analyze the orientation, density, mean length of joints revealed on the images of rock surfaces. The software developed in this study was named as JointeXtractor. As applying this system into several field measurements, the orientation, density, mean length of joints could be quantitatively measured through analyzing the images of rock surfaces, in which the case of a difficult-to-access area was especially included for the test of the system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1213-1219
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• 2012

A remote $CO_2$ laser system can rapidly change both the distance and the direction of the laser beam by moving a lens and rotating mirrors. It is then easy to weld complex patterns of weld lines. A conventional spot weld joint specimen and a remote $CO_2$ laser weld joint specimen with complex weld line patterns were prepared and tested both statically and dynamically. The relationships between the fatigue strength, i. e. the maximum cyclic force, and the fatigue life were obtained. The fatigue strength of the tested welded joints at two million cycles was found to be approximately 10% of the static strength. Furthermore, it was observed that the fatigue fracture mode changed with the level of the applied cyclic force. The fatigue crack origins were confirmed as the highest stress points found in the structural analysis. The maximum cyclic stress for different weld patterns converges as the fatigue life approaches two million cycles.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.3
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• pp.110-118
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• 2000

For reasonable fatigue design and estimation of fatigue durability considered fatigue strength and stiffness of the automotive body structure, many fatigue data must be insured according to the shapes, materials, and welding conditions of the spot welded lap joints. However, because it is actually difficult problem, there is need to establish a new method to be able to predict its fatigue life without any additional fatigue tests. Therefore, In order to improve such problems, in this study, the maximum stress function presenting the $\delta\sigma_{1max}―\delta P$ relation was defined form the relation between $\delta\sigma_{1max}-N_f$ and ${\delta}P-N_f$. By using the fatigue data on the IB type spot-welded lap joints previously obtained from the fatigue test results, fatigue life of the spot-welded lap joint previously obtained from the fatigue test results, fatigue life of the spot-welded lap joint having a certain dimension was tried to predict without any additional fatigue tests. And, its result was verified by ${\delta}P-$N_f$ curves. Obtained conclusion are as follows, 1) a maximum stress function considered the relation of the maximum principal stress, fatigue load, and the effects of geometrical factors of the IB type spot-welded lap joint was suggested. 2) the fatigue life predicted by the maximum principal stress function and the relation of $\delta\sigma_{1max}-N_f$ was well agreed with the fatigue life obtained through the actual fatigue test result. 3) the fatigue life of the IB type spot-welded lap joint having a certain dimension is able to be predicted without any additional fatigue tests from the fatigue life prediction method by the maximum principal stress function.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.15 no.2
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• pp.93-97
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• 2009

Anatomy: Facet joint syndrome most often affects the lower back and neck and refers to pain that occurs in the facet joints, which are the connections between the vertebrae in the spine that enable the spine to bend and twist. Many physicians have believed that the usual lesion of facet syndrome was an anatomical impairments of facet joint itself.. Facet joint injection using local anesthetics is a reliable method for the diagnosis and treatment for facet syndrome. Etiology: One of many possible causes is imbalances that can occur in stress levels, hormone levels, and nutritional levels. These imbalances can adversely affect posture, which can lead to neck and back pain. The common disorder called facet syndrome exhibits lower back pain, with or without, radiating pain to buttock and thigh due to facet joint arthropathy. Pain in the facet joint is supposedly the secondary effect of narrowing of joint space by sustained muscle contracture around joints. Syndrome: Facet joint syndrome tends to produce pain or tenderness in the lower back that increases with twisting or arching the body, as well as pain that moves to the buttocks or the back of the thighs. Other symptoms include stiffness or difficulty standing up straight or getting out of a chair. Pain can be felt in other areas such as the shoulders or mid-back area. Treatment: Non-drug treatments include hot packs, ultrasound, electrical stimulation, and therapeutic exercises. Stimulating blood flow using massage or a hot tub may also help. Alternative treatments include yoga and relaxation therapy. If your pain persists after trying these treatments, a surgical procedure called radiofrequency rhizotomy, which destroys the sensory nerves of the joint, may bring relief. Facet joint injection has been helpful in diagnosis and therapy for this facet syndrome. Radiofrequency thermocoagulation of medial branches is known to be an effective method of relieving pain caused by facet joint problems. We conclude that spasmolytic treatment of muscles connecting the two vertebral articular space would be better for treatment and diagnosis of facet syndrome rather than facet block with local anesthetic and steroid only.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.445-453
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• 2014

The purpose of this study was to analyze the gait characteristics and interaction between lower extremity joints according to shoe's heel heights in young women. Participants were selected as subject consisted of young and healthy women (age: $23.71{\pm}1.49yrs$, height: $165.92{\pm}2.00cm$, body weight: $54.37{\pm}3.46kg$) and walked with 3 types of shoe's high-heel (0, 5, 9 cm). The variables analyzed consisted of the displacement of Y axis in center of mass ([COM]; (position, velocity), front rear(FR) and left right(LR) angle of trunk, lower extremity joint angle (hip, knee, ankle) and asymmetric index (AI%). The displacement of Y axis in COM position showed the greater movement according to increase of shoe's heel heights, but velocity of COM showed the decrease according to increase of shoe's heel heights during gait. The hip and knee angle didn't show significant difference statistically according to increase of shoe's heel height, but left hip and knee showed more extended posture than those of right hip and knee angle. Also ankle angle didn't show significant difference statistically, but 9 cm heel showed more plantarflexion than those of 5 cm and 0 cm. The asymmetric index (AI%) showed more asymmetric 9 cm heel than those of 0 cm and 5 cm. The FR and LR angle in trunk tilting didn't show significant difference statistically according to the increase of shoe's heel height during gait in young women.

• Biomolecules & Therapeutics
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• v.28 no.5
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• pp.414-422
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• 2020

Fangchinoline (FAN) is a bisbenzylisoquinoline alkaloid that is widely known for its anti-tumor properties. The goal of this study is to examine the effects of FAN on arthritis and the possible pathways it acts on. Human fibroblast-like synovial cells (FLS), carrageenan/kaolin arthritis rat model (C/K), and collagen-induced arthritis (CIA) mice model were used to establish the efficiency of FAN in arthritis. Human FLS cells were treated with FAN (1, 2.5, 5, 10 µM) 1 h before IL-1β (10 ng/mL) stimulation. Cell viability, reactive oxygen species measurement, and western blot analysis of inflammatory mediators and the MAPK and NF-κB pathways were performed. In the animal models, after induction of arthritis, the rodents were given 10 and 30 mg/kg of FAN orally 1 h before conducting behavioral experiments such as weight distribution ratio, knee thickness measurement, squeaking score, body weight measurement, paw volume measurement, and arthritis index measurement. Rodent knee joints were also analyzed histologically through H&E staining and safranin staining. FAN decreased the production of inflammatory cytokines and ROS in human FLS cells as well as the phosphorylation of the MAPK pathway and NF-κB pathway in human FLS cells. The behavioral parameters in the C/K rat model and CIA mouse model and inflammatory signs in the histological analysis were found to be ameliorated in FAN-treated groups. Cartilage degradation in CIA mice knee joints were shown to have been suppressed by FAN. These findings suggest that fangchinoline has the potential to be a therapeutic source for the treatment of rheumatoid arthritis.