• PNF and Movement
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• v.19 no.3
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• pp.375-382
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• 2021

Purpose: The objectives of the present study were to investigate the disadvantages of tire pressure asymmetry of a wheelchair tire and recommend the criterion for appropriate tire pressure without generating negative changes in the musculoskeletal system in asymptomatic participants. Methods: Fourteen asymptomatic participants were asked to sit in pressure-controlled wheelchairs and perform desk work for 20 minutes in each tire condition. The asymmetry of the tire conditions was set as 0% difference, 25% difference, and 50% difference from the recommended pressure. The pelvic alignment and muscular recruitment represented as a flexion-relaxation ratio (FRR) were measured at pre-test, and after each condition of desk work. The displacement of the center of pressure (COP) was measured during the desk work. Results: The tire air pressure condition significantly affected the FRR and COP (P < 0.05). Both sides of the FRR values were significantly higher under the symmetrical tire conditions (0% difference) and pre-test, compared with the asymmetrical tire condition of 50% difference (P < 0.05). The mediolateral COP displacement of the asymmetrical tire conditions (25% and 50% difference) was significantly higher than that of the symmetrical tire conditions (0%) (P < 0.05). Conclusion: Asymmetrical tire conditions could cause changes in the muscle recruitment pattern of the erector spine and mediolateral COP displacement. Tire pressure asymmetry higher than 50% could be a risk factor for prevalence of back pain, so this level of asymmetry in tire pressures should be cautioned against for wheelchair users.

• Journal of the Korean Geotechnical Society
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• v.29 no.6
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• pp.63-75
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• 2013

Inclined Earth Retaining Structure Method (IER Method), was developed in order to improve the mechanical properties of the existing earth retaining method. IER consists of two supports, which are front and back supports. In the IER method, back support is very effective for the reduction of the earth pressure acting on the front support. In this study, the effects of back support and fixing conditions of lower ends of supports are analysed by laboratory model tests in clay. The test results show that back support reduces the Leteral displacement of IER effectively, and according to the results the effect of interval and fixing condition of back support was analysed.

• The Journal of Korean Physical Therapy
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• v.17 no.3
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• pp.311-327
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• 2005

The purpose of this study was to investigate the effects of diaphragmatic breathing on activation of trunk muscles of patients with low back pain. Diaphragmatic breathing may affect activation of trunk muscles. The assumptions are as follows: the crural diaphragm attatches to the lumbar vertebrae from L1 to L3, the voluntary downward pressurization of the diaphragm increases intra-abdominal pressure, and this increases the stiffness of the spine. Diaphragmatic breathing increases intra-abdominal pressure and the increased intra-abdominal pressure may contribute to the lumbar stability. Sixty patients with low back pain were randomly divided into two groups. Experimental group performed diaphragmatic breathing exercise with six breathing positions and control group performed only the breathing positions for five times per week during six weeks. % maximal voluntary contraction(% MVC) of trunk muscles on six breathing positions of experimental and control group was measured according to testing period of pre test, three weeks, and six weeks. The repeated measures of one-way ANOVA were used to analyze % MVC on trunk muscles of experimental and control group according to testing period. The results of this study were as follows: First, % MVC of right and left erector spinae in the right leg extension position indicated the statistically significant difference in experimental group which performed diaphragmatic breathing exercise rather than control group (p<0.05). Second, % MVC of right and left erector spinae in all-four positions indicated the statistically significant difference in experimental group which performed diaphragmatic breathing exercise rather than control group (p<0.05). Third, % MVC of right and left erector spinae, external oblique in the sitting position indicated the statistically significant difference in experimental group which performed diaphragmatic breathing exercise rather than control group (p<0.05). Fourth, % MVC of right and left erector spinae, external oblique in the standing position indicated the statistically significant difference in experimental group which performed diaphragmatic breathing exercise rather than control group (p<0.05). Fifth, % MVC of right and left erector spinae, external oblique in the supine position indicated the statistically significant difference in experimental group which performed diaphragmatic breathing exercise rather than control group (p<0.05). Sixth, % MVC of right and left erector spinae, external oblique in the lying on prone position indicated the statistically significant difference in experimental group which performed diaphragmatic breathing exercise rather than control group (p<0.05). In conclusion, as experimental group performed diaphragmatic breathing exercise according to the period of pre-test, post three weeks, and post six weeks, experimental group showed the greater significant effect on the activation of right, left erector spinae, and external oblique muscle. Diaphragmatic breathing exercise which resulted in activation of trunk muscles can be effective for managing the patients with back pain and should be utilized as the new therapeutic intervention.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.45-57
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• 2016

The Inclined Earth Retaining Structure (IER) is the structure using an integrated system of both front supports and inclined back supports to increase the stability for excavation. The IER is a structurally stable temporary excavation method using the back supports restraining the lateral displacement of the front supports as stabilizing piles. The back supports connected to the front supports significantly reduce the earth pressure acting on both the front wall and the front supports by distributing it to the back supports in order to increase the structural stability. In this study, mechanical behaviors of IER according to the head connection type using fixed- or hinge-connection were found by performing numerical analysis and laboratory model tests in the sandy ground. The maximum lateral displacement of fixed-connection was 88% of that of hinge-connection in the numerical analysis. The lateral displacement of fixed-connection was 7% of that of hinge-connection in the laboratory model test results. Furthermore, the earth pressure of the fixed-connection was 67% of that of the hinge-connection in the shear-strain analysis results of the model ground.

• Fashion & Textile Research Journal
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• v.7 no.3
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• pp.309-314
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• 2005

This study was to determine whether the massage would enhance the physical relaxation in healthy women, and whether the effects of massage on the relaxation would be different by the applied regions of the body. Five healthy young women participated in the two test sessions of back and lower extremities massage in a chamber controlled at an air temperature of $28^{\circ}C$ and a relative humidity of $50{\pm}5%$. The slow stroke massage with lavender aroma oil for 30 minutes was applied to the subjects with a 10-min. and a 20-min rest time before and after the application, respectively. Rectal temperature decreased and the chest and thigh skin temperatures increased with the massage application, and the changes of the temperatures were greater with lower extremities massage than with back massage. Heart rate also decreased during massage period and tended to be lower with lower extremities massage. Systolic and diastolic blood pressure decreased with lower extremities massage. These results show that the slow stroke massage for 30 minutes can induce physiological responses related with the enhanced relaxation in healthy women, and lower extremities massage is more effective on the physical relaxation rather than back massage.

• Fashion & Textile Research Journal
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• v.14 no.6
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• pp.960-967
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• 2012

The study aims to design the corset type long-line bra patterns that compensate part-somatotype of women in their 20s. The corset type long-line research bra patterns consist of 4 sections: cup, front bodice, back bodice, and shoulder strap. The full cup is made up of 2 lower part pieces and 1 upper part piece, and the shoulder strap is 16 millimeters wide. The method to design the patterns is shown in figure 4 and figure 5. The result of wearing test showed that, while the wearing testers recognized some significant differences in 19 out of 26 criteria, the examiners did in 17 out of 23. The criteria more than 1 in an average value between research bras and commercial bras were 'appropriateness of breadth of shoulder strap', 'appropriateness of pressure of armhole circumference'. 'appropriateness of pressure of waist', 'suitability of side line and body curve', 'appropriateness of positional pressure of chest circumference', 'appropriateness of positional pressure of upper part line', 'appropriateness of positional pressure of bottom part line', and 'satisfaction of whole silhouette of side and back'. The research and commercial bras were evaluated 4.23 and 3.44 respectively by the testers, and 4.25 and 3.40 by the examiners. The former ones were scored higher by both parties. They were also appreciated higher in general silhouettes of fitting and appearance.

• Advanced Composite Materials
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• v.18 no.3
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• pp.233-249
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• 2009

Safe installation and operation of high-pressure composite cylinders for hydrogen storage are of primary concern. It is unavoidable for the cylinders to experience temperature variation and significant thermal input during service. The maximum failure pressure that the cylinder can sustain is affected due to the dependence of composite material properties on temperature and complexity of cylinder design. Most of the analysis reported for high-pressure composite cylinders is based on simplifying assumptions and does not account for complexities like thermo-mechanical behavior and temperature dependent material properties. In the present work, a comprehensive finite element simulation tool for the design of hydrogen storage cylinder system is developed. The structural response of the cylinder is analyzed using laminated shell theory accounting for transverse shear deformation and geometric nonlinearity. A composite failure model is used to evaluate the failure pressure under various thermo-mechanical loadings. A back-propagation neural network (NNk) model is developed to predict the maximum failure pressure using the analysis results. The failure pressures predicted from NNk model are compared with those from test cases. The developed NNk model is capable of predicting the failure pressure for any given loading condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.888-895
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• 2006

In this study, anisotropically consolidated undrained shear(CAU) test was performed to examine the variation of the shear strength according to the stress history. The specimen having 30% relative density was homogeniously prepared, and 200KPa of back pressure was applied to increase the B value more than 0.95. To make NC specimens, the vertical stress was applied on the specimen by 100KPa, 200KPa and 400KPa, and to make OC specimens, the vertical stress was applied upto 400KPa and was reduced to 200KPa and 100KPa resulting in OCR 2 and 4 respectively. The test result indicates the shear strength for the OC specimens are slightly higher then that of the NC specimens at the same confining pressure. The elastic modulus varies according to the confining stress and considerably affected by preconsolidation stress.

• Journal of the Korean Geotechnical Society
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• v.21 no.1
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• pp.123-131
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• 2005

In this research, shaking table tests for three types of gravity quay wall system were performed to analyze the influence of excess pore pressure in backfill soils on the natural frequency of gravity quay wall systems. The elastic modulus of backfill soils was also estimated from the back analyses using the results of the shaking table tests. From the test results, it was observed that as the magnitude of excess pore pressures increased, the natural frequency of the gravity quay wall system decreased and vice versa. The natural frequency was about 44Hz when no excess pore pressure was generated in backfill soils, and decreased to about 16Hz at the pore pressure ratio of 0.55. The elastic modulus of backfill soils reached the constant maximum value when the pore pressure ratio was less than 0.2, and abruptly decreased as the pore pressure ratio became larger than that. The elastic modulus of backfill soils decreased to $10\%$ of the maximum value when the pore pressure ratio was 0.55.

• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.83-96
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• 2016

The surface settlement of the back ground of a braced wall due to the ground excavation has the great influence on the safety of the surrounding area. But it is not easy to predict the settlement of the surrounding area due to proud excavation. Estimation of the settlement of the surface ground induced by the deformation of the braced wall is performed by FEM and empirical method (Peck, Clough etc). In this research, surface settlement of the back ground braced wall depending on the joint dips in rocks during excavating the composit ground was measured at the large scale model test (standard: $0.3m{\times}0.3m{\times}0.5m$). The scale of model test was 1/14.5 and the ground was excavated in ten steps. Earth pressure on the braced wall and ground surface settlement on the back ground of a braced wall were investigated. The surface settlement during the excavation depended on the joint dips in rocks on of the ratio of rock layer. Maximum earth pressure and maximum surface settlement were masured at the same excavation step. In accordance with the increase of the rock layer dips and rock layer ratio, the ground surface settlement increased. The maximum ground surface settlement was 17 times larger at 60 degree joint dips in rocks than that of the horizontal ground conditions. And the position of the maximum surface settlement by empirical method was calculated at the point, which was 17%~33% of excavation depth. In accordance with the increase of the rock layer dips and rock layer ratio, the ground maximum surface settlement increased. The ground surface settlement of composite ground is smaller than that of the empirical.