• Structural Engineering and Mechanics
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• v.15 no.1
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• pp.39-52
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• 2003

A computer program has been developed for the optimum design of prestressed concrete beams under flexure. Optimum values of prestressing force, tendon configuration, and cross-sectional dimensions are determined subject to constraints on the design variables and stresses. 28 constraints have been used including flexural stresses, cover requirement, the aspect ratios for top and bottom flanges and web part of a beam and ultimate moment. The objective function contains cost of concrete, prestressing force and formwork. Using this function, it is possible to obtain minimum cost design, minimum weight or cross-sectional area of concrete design and minimum prestressing force design. Besides the idealized I-shaped cross-section, which is widely used in literature, a general I-shaped cross-section with eight geometrical design variables are used here. Four examples, one of which is available in the literature and the others are modified form of it, have been solved for minimum cost and minimum cross-sectional area designs and the results are compared. The computer program, which employs modified grid search optimization method, can assist a designer in producing efficient designs rapidly and easily. Considerable savings in computational work are thus made possible.

• The Journal of Korean Physical Therapy
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• v.26 no.5
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• pp.324-330
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• 2014

Purpose: The aim of the current study was to compare the muscle architecture of lower extremity using rehabilitative ultrasound imaging (RUSI) in young adults in Seoul and Hanoi. Methods: The study design was a comparative study of muscle cross-sectional area of lower extremity. Sixty healthy young subjects (Seoul group: 30, Hanoi group: 30) participated in this study. Real-time B-mode RUSI with a 7.5MHz linear transducer was used for measurement of cross-sectional area, pennation angle, and muscle thickness of the rectus femoris, tibialis anterior, and medial gastrocnemius muscles. Independent t-test was used for statistical analysis. Results: Significant difference in cross sectional area of rectus femoris was observed between Korean young adults and Hanoi young adults (p<0.01). Muscle thickness and pennation angle of tibialis anterior in Korean young adults were greater than in Hanoi young adults (p<0.01). In addition, the muscle thickness and pennation angle of the medial part of gastrocnemius muscle were greater in Korean young adults than in Hanoi young adults (p<0.01). In addition, in the results for gender, men had larger muscle architectures than women in both groups (p<0.01). Conclusion: This study, using RUSI, showed significant difference in muscle architectures of lower extremity in a diverse group of young adults RUSI.

• Journal of Korean Neurosurgical Society
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• v.59 no.3
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• pp.276-281
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• 2016

Objective : Although trunk muscles in the lumbar spine preserve spinal stability and motility, little is known about the relationship between trunk muscles and spinal fusion rate. The aim of the present study is to evaluate the correlation between trunk muscles cross sectional area (MCSA) and fusion rate after posterior lumbar interbody fusion (PLIF) using stand-alone cages. Methods : A total of 89 adult patients with degenerative lumbar disease who were performed PLIF using stand-alone cages at L4-5 were included in this study. The cross-sectional area of the psoas major (PS), erector spinae (ES), and multifidus (MF) muscles were quantitatively evaluated by preoperative lumbar magnetic resonance imaging at the L3-4, L4-5, and L5-S1 segments, and bone union was evaluated by dynamic lumbar X-rays. Results : Of the 89 patients, 68 had bone union and 21 did not. The MCSAs at all segments in both groups were significantly different (p<0.05) for the PS muscle, those at L3-4 and L4-5 segments between groups were significantly different (p=0.048, 0.021) for the ES and MF muscles. In the multivariate analysis, differences in the PS MCSA at the L4-5 and L5-S1 segments remained significant (p=0.048, 0.043 and odds ratio=1.098, 1.169). In comparison analysis between male and female patients, most MCSAs of male patients were larger than female's. Fusion rates of male patients (80.7%) were higher than female's (68.8%), too. Conclusion : For PLIF surgery, PS muscle function appears to be an important factor for bone union and preventing back muscle injury is essential for better fusion rate.

• Journal of Korean Academy of Nursing
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• v.37 no.1
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• pp.81-90
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• 2007

Purpose: The purpose of this study was to examine the effects of daily exercise before steroid treatment on mass, the type I and II fiber cross-sectional area, and myofibrillar protein content of hindlimb muscles in a rat model. Method: Adult male Sprague-Dawley rats were randomly assigned to one of three groups: a control group(n=10) that had a normal saline injection for 7days, a steroid group(n=10) that had a steroid injection for 7days, and an exercise-steroid group(n=10) that ran on the treadmill for 7days before a steroid treatment. Body weight and food intake were measured every day. At 15 days all rats were anesthetized and the soleus, plantaris and gastrocnemius muscles were dissected. Result: The exercise-steroid group showed significant increases as compared with the steroid group in body weight, muscle weight of the soleus and gastrocnemius, type II muscle fiber cross-sectional area of plantaris, and myofibrillar protein content of the soleus, plantaris, and gastrocnemius. As compared with the control group, the steroid group showed significant decreases in body weight and diet intake, muscle weight, the type II fiber cross-sectional area and myofibrillar protein content of the soleus, plantaris, and gastrocnemius muscles. Conclusion: Daily exercise before steroid treatment attenuates hindlimb muscle atrophy, with type II muscle changes more apparent than type I muscle changes.

• The Korean Journal of Pain
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• v.33 no.1
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• pp.60-65
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• 2020

Background: Anatomic changes in the acromion have been considered a main cause of shoulder impingement syndrome (SIS). To evaluate the relationship between SIS and the acromion process, we devised a new morphological parameter called the acromion process cross-sectional area (APA). We hypothesized that the APA could be an important morphologic diagnostic parameter in SIS. Methods: We collected APA data from 95 patients with SIS and 126 control subjects who underwent shoulder magnetic resonance imaging (MRI). Then we measured the maximal cross-sectional area of the bone margin of the acromion process on MRI scans. Results: The mean of APAs were 136.50 ± 21.75 ㎟ in the male control group and 202.91 ± 31.78 ㎟ in the male SIS group; SIS patients had significantly greater APAs (P < 0.001). The average of APAs were 105.38 ± 19.07 ㎟ in the female control group and 147.62 ± 22.90 ㎟ in the female SIS group, and the SIS patients had significantly greater APAs (P < 0.001). The optimal APA cut-off in the male group was 165.14 ㎟ with 90.2% sensitivity, 91.4% specificity, and an area under the curve (AUC) of 0.968. In the female group, the optimal cut-off was 122.50 ㎟ with 85.2% sensitivity, 84.9% specificity, and an AUC of 0.928. Conclusions: The newly devised APA is a sensitive parameter for assessing SIS; greater APA is associated with a higher possibility of SIS. We think that this result will be helpful for the diagnosis of SIS.

• Clinics in Shoulder and Elbow
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• v.22 no.2
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• pp.70-78
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• 2019

Background: This study evaluated postoperative changes in the supraspinatus from time-zero to 6 months, using magnetic resonance imaging (MRI). We hypothesized that restoration of the musculotendinous unit of the rotator cuff by tendon repair immediately improves the rotator cuff muscle status, and maintains it months after surgery. Methods: Totally, 76 patients (29 men, 47 women) with rotator cuff tears involving the supraspinatus tendon who underwent arthroscopic rotator cuff repairs were examined. MRI evaluation showed complete repair with intact integrity of the torn tendon at both time-zero and at 6 months follow-up. All patients underwent standardized MRI at our institution preoperatively, at 1 or 2 days postoperative, and at 6 months after surgery. Supraspinatus muscular (SSP) atrophy (Thomazeau grade) and fatty infiltrations (Goutallier stage) were evaluated by MRI. The cross-sectional area of SSP in the fossa was also measured. Results: As determined by MRI, the cross-sectional area of SSP significantly decreased 11.41% from time-zero (immediate repair) to 6 months post-surgery, whereas the Goutallier stage and Thomazeau grade showed no significant changes (p<0.01). Furthermore, compared to the preoperative MRI, the postoperative MRI at 6 months showed a no statistically significant increase of 8.03% in the cross-sectional area. In addition, morphological improvements were observed in patients with high grade Goutallier and Thomazeau at time-zero, whereas morphology of patients with low grade factors were almost similar to before surgery. Conclusions: Our results indicate that cross-sectional area of the initial repair appears to decrease after a few months postoperatively, possibly due to medial retraction or strained muscle.

• Journal of Veterinary Clinics
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• v.39 no.6
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• pp.334-341
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• 2022

A decrease in the paraspinal muscle cross-sectional area (CSA) and functional cross-sectional area (FCSA) are associated with low back pain and disc herniation in humans. This study examined whether chronicity or lateralization of disc herniation affects the CSA and FCSA of the paraspinal muscles. The CSA and FCSA of the paraspinal muscles between the 12th and 13th thoracic vertebrae were measured in 31 dogs with intervertebral disc herniation (IVDH). The muscle CSA and FCSA were evaluated by dividing the values of the body weight, spinal disc CSA, and spinal canal CSA to offset the differences in body type between subjects. In the chronic IVDH group, the ratio of the paraspinal muscle CSA divided by the body weight was significantly lower, and fat infiltration in the paraspinal muscle was significantly higher than in the acute group. The lateralization of the disc herniation was significantly related to the changes in the paraspinal muscle CSA. In the right-sided disc herniation group, right epaxial muscle CSA was significantly reduced compared to the left-sided disc herniation group. The change in the paraspinal muscle might be a helpful indicator to localize less obvious disc pathologies and target the search for the pathology responsible for disc-related symptoms in dogs.

• Journal of radiological science and technology
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• v.46 no.5
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• pp.427-433
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• 2023

This study aimed to quantitatively compare the diameters measured directly from the coronal plane or sagittal plane of 2D digital subtraction angiography (DSA) and the cross-sectional area-converted diameters calculated from contrast-enhanced MR (CE-MR) imaging. A retrospective analysis was conducted on 20 patients who underwent both 2D DSA and CE-MR imaging. Firstly, the venous diameters of the superior sagittal sinus (SSS) and transverse sinus (TS) were directly measured from 2D DSA. Subsequently, the axial planes for SSS diameter and the sagittal plane for TS in CE-MR imaging were utilized to calculate cross-sectional area-based converted diameters. The numerical values obtained from 2D DSA and CE-MR imaging were compared pairwise at each location. For SSS, the diameter measured by 2D DSA was 27% larger than the conversion-based diameter from CE-MR imaging (9.8±1.4 mm vs. 7.1±1.3 mm, P<0.05). Similarly, for the right TS, the difference was 16% (8.8±3.2 mm vs. 7.4±2.0 mm, P<0.05), and for the left TS, the difference was 22% (8.4±2.8 mm vs. 6.6±1.3 mm, P<0.05). In conclusion, the diameter measured directly in conventional 2D DSA may be larger than the diameter converted based on the cross-sectional area. Therefore, when selecting the size of the stent, it is crucial to make precise determinations while keeping this fact in mind.

• Computers and Concrete
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• v.32 no.4
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• pp.351-363
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• 2023

Reducing the self-weight of reinforced concrete structures problem is discussed in this paper by using two types of self-weight reduction, the first is by using lightweight coarse aggregate (crushed brick) and the second is by using styropor block. Experimental and Numerical studies are conducted on (LWAC) lightweight aggregate reinforced concrete slabs, having styropor blocks with various sizes of blocks and the ratio of shear span to the effective depth (a/d). The experimental part included testing eleven lightweight concrete one-way simply supported slabs, comprising three as reference slabs (solid slabs) and eight as styropor block slabs (SBS) with a total reduction in cross-sectional area of (43.3% and 49.7%) were considered. The holes were formed by placing styropor at the ineffective concrete zones in resisting the tensile stresses. The length, width, and thickness of specimen dimensions were 1.1 m, 0.6 m, and 0.12 m respectively, except one specimen had a depth of 85 mm (which has a cross-sectional area equal to styropor block slab with a weight reduction of 49.7%). Two shear spans to effective depth ratios (a/d) of (3.125) for load case (A) and (a/d) of (2) for load case (B), (two-line monotonic loads) are considered. The test results showed under loading cases A and B (using minimum shear reinforcement and the reduction in cross-sectional area of styropor block slab by 29.1%) caused an increase in strength capacity by 60.4% and 54.6 % compared to the lightweight reference slab. Also, the best percentage of reduction in cross-sectional area is found to be 49.7%. Numerically, the computer program named (ANSYS) was used to study the behavior of these reinforced concrete slabs by using the finite element method. The results show acceptable agreement with the experimental test results. The average difference between experimental and numerical results is found to be (11.06%) in ultimate strength and (5.33%) in ultimate deflection.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.382-389
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• 2000

The purpose of present study is to investigate for reducing pressure fluctuations in tile case of installing tile air-shafts on the side wall of the tunnel with small cross-sectional area on conventional line. Experiments were performed with a 1/61-scale moving model rig for the tunnel of 0.764km length in the condition of tunnel cross-section area of 28 ㎡ According to the results, the maximum pressure fluctuation is reduced by 45% for 19 air-shafts. This results have the speed-up effects of about 33.4km/h for the train running in tunnel.