• Structural Engineering and Mechanics
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• v.91 no.5
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• pp.503-516
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• 2024

The present research examines the primary resonance (PR) behaviors of oblique stiffened multilayer functionally graded (OSMFG) shallow shells featuring an FG porous (FGP) core under an external excitation. The research considers two distinct types of FGP cores: one characterized by uniform porosity distribution (UPD) and the other by non-uniform porosity distribution (NPD) along the thickness direction. Furthermore, the study explores two types of shallow shells: one with external oblique stiffeners and one with internal oblique stiffeners, which might have angles that are similar or different from each other. Using the stress function alongside the first-order shear deformation theory (FSDT), the research establishes a nonlinear model for OSMFG shallow shells. The strain-displacement relationships are obtained utilizing FSDT and von-Kármán's geometric assumptions. The Galerkin approach is utilized to discretize the nonlinear governing equations, allowing for the analysis of stiffeners at varied angles. To validate the obtained results, a comparison is made not only with the findings of previous research but also with the response of PR obtained theoretically with the method of multiple scales, using the P-T method. Renowned for its superior accuracy and reliability, the P-T method is deemed an apt selection within this framework. Additionally, the study investigates how differences in material characteristics and stiffener angles affect the system's PR behaviors. The results of this study can be used as standards by engineers and researchers working in this area, and they can offer important information for the design and evaluation of the shell systems under consideration.

• Physical Therapy Korea
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• v.11 no.4
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• pp.19-29
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• 2004

Many muscles of the trunk and hip are capable of contributing to the stabilization and protection of the lumbar spine. To have optimal effectiveness, a training program should include dynamic back/stomach/hip exercises. This study was designed to assess the L5 level paraspinal, external abdominal oblique, and gluteus maximus muscle activities during various low back stabilization exercises. Participants were 26 healthy adults (13 males, 13 Females), aged 21 to 28 years. The surface electromyography (EMG) was recorded from the L5 level paraspinal, external abdominal oblique, and gluteus maximus muscles. The recorded signal was averaged and normalized to the maximal electromyographic amplitude obtained during the maximal voluntary contraction. The measurements were taken during 3 low back stabilization exercises. One-way analysis of variance with repeated measures was used to examine the difference, and a post hoc test was performed with least significant difference. A level of significance was set at p<.05. The significance of difference between men and women, and between the electromyographic recording sites was evaluated by an independent t-test. The EMG activity for the externus oblique and gluteus maximus muscles had significant differences among 3 exercises (p<.05). In males, the EMG activity for the external abdominal oblique muscle had significantly increased differences during exercises 1 and exercise 2 (p<.05). The gluteus maximus muscle had significantly increased differences during exercise 2 and exercise 3 (p<.05). In females, the multifidus muscle had significantly increased difference during exercise 3 (p<.05), the external abdominal oblique muscle had significantly increased difference during exercise 1 (p<.05). and the gluteus maximus muscle had significantly decreased difference during exercise 3 (p<.05). The results were that the external abdominal oblique muscle was apparently activated during the curl-up exercise in females and males, and the multifidus muscle was apparently activated during the bridging exercise in females and during the sling exercise in males and females.1)In comparison of the %MVC between males and females, exercise 2 and exercise 3 apparently activated of the multifidus and gluteus maximus muscles in both males and females (p<.05). The EMG activity of the gluteus maximus muscle of the males significantly increased during exercise 2 and exercise 3 (p<.05). The EMG activity the multifidus muscle of the females was significantly increased during exercise 2 and exercise 3 (p<.05). More research is needed to understand the nature of motor control problems in the deep muscles in patients with low back pain.

• The Journal of Korean Physical Therapy
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• v.19 no.5
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• pp.1-10
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• 2007

Purpose: Leg-crossing sitting is very common for men and woman. No solid evidence exists for either a beneficial or a detrimental effect of this posture. This study investigated the change of activities of trunk muscles between the normal group and the low back pain group during various leg-crossing positions. Methods: The subjects were consisted of 10 subjects who don't have low back pain and 10 subjects who have low back pain. In this study, we used electromyography(EMG) to evaluate the activities of both the trunk muscles (rectus abdominis, external oblique, internal oblique, and multifidus) during various leg-crossing positions (up-right, leg-crossing, tailor-crossing, and ankle-crossing). We analyzed the data by using repeated one way ANOVA. Results: In normal group, there were increased in EMG activities of trunk muscles, but no significant differences during leg-crossing positions. In back pain group, there were increased in EMG activities of right external oblique, left. internal oblique, and both multifidus muscles in leg-crossing and tailor-crossing position, but no significant differences during leg-crossing positions. There was no significant difference of muscle activity of trunk muscles between the back pain group and the normal group. Conclusion: We suggest that low back pain people who have weak muscles of rectus abdominis, external and internal oblique are often experienced in leg-crossing posture than normal. To compensate this unstability of trunk, leg-crossing posture is substituted passive structure for activities of active muscle.

• Journal of Korean Physical Therapy Science
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• v.29 no.1
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• pp.64-72
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• 2022

Background: The purpose of this study is to investigate the effect of wall squat exercise according to the difference in the support surface on the thickness change of external oblique, internal oblique and transverse abdominalis of the trunk muscles and the change in distance of center of pressure when the eyes are opened and closed. Design: Randomized controlled trial. Methods: The subjects were 26 healthy adults, 18 males and 8 females. The composition of each group using the single-blind method was 13 people in the unstable side wall squat exercise group and 13 people in the stable side wall squat exercise group. Experimental measurements were divided into before, 3 weeks, and 6 weeks after the experiment, and changes in muscle thickness and balance were confirmed. Muscle thickness was measured using ultrasinic, and static balance change was measured using Bio-rescue. Results: There were significant differences in the thickness changes of external oblique, internal oblique and transverse abdominalis according to the wall squat exercise method by period and in the interaction between the period and the group (p<0.05). As a result of the post-hoc analysis, there was a significant difference in the change between the two groups in external oblique muscle after 6 weeks. And there was a significant difference in the distance of the pressure center between eyes open and closed eyes (p<0.05). Conclusion: In terms of instability, wall squat exercise was positive for changes in trunk muscle thickness. It suggests the possibility of using it for trunk muscle strengthening training in the future.

• Archives of Plastic Surgery
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• v.37 no.3
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• pp.277-280
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• 2010

Purpose: The resection of locally advanced or recurred breast cancers frequently result in large chest wall defects and it leads to a great challenges to cover. Generally simple skin grafts are not a practical option for patients because of their poor cosmetic appearance and prognosis. The latissimus dorsi and rectus abdominis musculocutaneous flap have traditionally been recommended for closure of these large defects. Though the cosmetic result of reconstruction using these flaps is often excellent, but has significant drawbacks. Therefore, we thought that chest wall reconstruction using the external oblique musculocutaneous flap can be an alternative method for extensive chest wall defect related to large, locally advanced breast carcinoma. Methods & Results: We present a case of a 50-year-old Korean female, refered to our department with a left breast tumor for 10 months. CT demonstrate a large tumor on the left anterior chest wall and multiple nodules of varying size in the cervical areas and liver. FDG-PET showed areas of hot uptake throughout the left chest wall, mediastinum and liver. Biopsy was consistent with invasive ductal carcinoma (Grade III). The initial tumor was considered inoperable, so a series of chemotherapy was initiated. Though the size of the breast mass was slightly decreased, the patient continued to suffer from purulent discharge, unpleasant odor and contact bleeding of the mass, the salvage mastectomy was performed. Conclusion: We could reconstruct $23{\times}16\;cm$ sized large chest wall defect, resulting from the resection of a locally advanced breast carcinoma, using an external oblique musculocutaneous flap successfully. Immediate postoperatively checked flap was healthy. Overall result was good without any significant complications and discharged 3 weeks after operation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.79-84
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• 2008

We are developing a small-sized high temperature superconducting magnetic energy storage (HTS-SMES) magnet with the nominal storage capacity of 600 kJ, which provides electric power with high quality to sensitive electric loads. Critical current and N-value of a high temperature superconductor with large current, which was selected for the development of the 600 kJ HTS-SMES magnet, were investigated in various oblique external magnetic fields. Based on the critical current and N-value measured for the short sample conductor, we discussed the DC V - I characteristic of a model coil fabricated with the same conductor of 500 m. The results show that the measured critical current and N-value of the conductor for parallel field are constant in external magnetic fields less than about 0.2 T. However, for oblique fields, its critical current and N -value abruptly decrease in all external magnetic fields. Moreover, the measured critical current of the model coil well agrees with the numerically calculated one based on the DC V - I characteristic measured for the short sample conductor. This suggest that losses and critical currents for an HTS-SMES magnet made up of a high temperature superconductor with anisotropic characteristic are predictable from the data of a short sample conductor.

• The Journal of Korean Physical Therapy
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• v.29 no.2
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• pp.80-84
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• 2017

Purpose: This study was conducted to examine the effects of different sizes of blood flow restriction areas on the thickness of the external oblique and biceps brachii. Methods: The study subjects were 52 adults who were divided into four groups that performed plank exercises over a six-week period after blood flow restriction. Changes in the thickness of the external oblique and biceps brachii were measured using ultrasonography before the experiment, then three and six weeks after the experiment. The changes in each variable over time were evaluated by repeated-measures analysis of variance (ANOVA). Results: The external oblique and biceps brachii showed significant differences in muscle thickness with regard to time and the interaction between time and each group (p<0.01), but no significant differences with regards to changes between groups (p>0.05). Conclusion: A larger blood flow restriction area resulted in a statistically significant increase in muscle thickness. The results of this study may be used as the basis for future studies and for rehabilitation in clinical practice.

• Physical Therapy Korea
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• v.16 no.3
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• pp.16-23
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• 2009

The purpose of this study was to investigate the effects of a repetitive lifting task on the level of activation and median frequency of the paraspinal muscles, and to provide basic data of the maximal acceptable duration of the lifting task to avoid muscle fatigue. Ten healthy male subjects were recruited as participants and they repetitively (12 lifts/min) lifted a box ($46cm{\times}30cm{\times}30cm$, 15 kg) for 10 minutes. Electromyographic data (muscle activation and median frequency), heart rate, and Borg CR10 score were recorded at 1, 3, 5, 7, and 9 minutes after the lifting task. Electromyographic data was recorded from the elector spinalis, mutifidus, external oblique abdominis, and rectus abdominis for 1 minute. The results showed that as the repetitive lifting task progressed, the heart rate and Borg CR10 score significantly increased. In addition, activation of the muscles increased. The median frequency significantly decreased over time in the elector spinalis, mutifidus, and external oblique abdominis (right side), except for the external oblique abdominis (left side) and rectus abdominis. It is suggested that the median frequency recorded from a dynamic task is used to monitor muscle fatigue. Furthermore, the repetitive lifting task (15 kg, 12 lifts/min) should not continue for more than 3 minutes in order to avoid muscle fatigue.

• PNF and Movement
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• v.16 no.3
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• pp.397-404
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• 2018

Purpose: The purpose of this study was to investigate the effect of climbing training combined with coordinative locomotor training on muscle thickness in normal adults and to provide basic data regarding its applicability to clinical practice. Methods: Coordinative locomotor and climbing training was conducted three times per week for six weeks. Each exercise session consisted of ten minutes of warm-up and 40 minutes of the main exercise. A post-test was conducted six weeks after the training began, and a follow-up test was done two weeks after the training ended. Results: There were significant differences in the participants' external and internal oblique abdominis muscles over time (p<0.05). There were also significant interactions in the external and internal oblique abdominis muscles over time and according to group (p<0.05). Conclusion: The findings indicate that coordinative locomotor training with climbing had positive effects in normal adults, including increased thickness of the external and internal oblique abdominis muscles. The findings hold value for patient rehabilitation and clinical applications and interventions using coordinative locomotor training in combination with climbing.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.91-99
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• 2019

PURPOSE: This study was conducted to evaluate the activity of trunk muscles according to width of the foot and posture of the arm during sit to stand (STS). METHODS: Thirty subjects were recruited and examined for variation in muscle activity of the erector spine, gluteus maximus, gluteus medius and external oblique during different STS conditions; namely, the cross arm basic sit to stand (CBSTS), overhead basic sit to stand (OBSTS), cross arm wide sit to stand (CWSTS), and overhead wide sit to stand (OWSTS). Repeated measures ANOVA (Analysis of Variance) was used for analysis. RESULTS: Erector spinae muscle activity showed a significant increase in the OBSTS condition (p<.05) and external oblique muscle activity showed a significant increase in the OWSTS condition ((p<.05). There was no significant difference in the activity of the gluteus maximus and gluteus medius under any conditions (p>.05). CONCLUSION: During evaluation of the performance of the STS, the CWSTS condition will be useful to decrease the muscle activity of the erector spinae and the OWSTS condition will be useful to increase the muscle activity of the external oblique. The results of this study can be used as an index to find a suitable exercise method for subjects who have back pain or to strengthen the abdomen.