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The purpose of this study was to determine whether combined intervention of treadmill exercise and bone marrow stromal cell (BMSC) transplantation would affect the expression of neurotrophic factors in the sciatic nerve injury (SNI) and neuropathic pain-related cascades in ipsilateral lumbar 4-5 dorsal root ganglion (DRG) during the early or late stage of sciatic nerve regeneration. The rats were randomly divided into the normal control group (CONT, n= 6), sedentary group (SS, n= 24), exercise group (SE, n= 24), BMSC transplantation group (SB, n= 24), BMSC transplantation+exercise group (SBE, n= 24) 1, 2, 3, and 5 weeks after SNI. Single dose of 5× 106 harvested BMSC was injected into the injury area sing by a 30 gauge needle. Treadmill exercise was performed at a speed of 8 m/min for 30 min once a day. Tropomyosin-receptor kinase B, brain-derived neurotrophic factor and ciliary neurotrophic factor were significantly upregulated in the SE and SBE groups at 1- and 2-week postinjury than those in the CONT and SS groups, and SB and SBE groups continuously kept up proinflammatory cytokines until the late stage of regeneration. Nuclear factor kappa-light-chain-enhancer of activated B cells, interleukin and tumor necrosis factor alpha in ipsilateral DRG were progressively decreased by exercise alone application and/or BMSC transplantation at early and late stage of regeneration. Present results provide reliable information that combined intervention of treadmill exercise and BMSC transplantation might be one of the effective treatment strategies for recovering sciatic nerve injury-induced neuropathic pain over time.

The purpose of this study is to investigate the effects of resistance circuit training on health-related physical fitness, plasma lipid and adiponectin in obese college students. Twenty male college students participated in this study and they were randomly divided into the sedentary group (SG, n = 10) and the resistance circuit training group (RCG, n = 10). The exercise group underwent the resistance circuit training program for 60 min 3 times a week for 12 weeks, while the sedentary group continued activities of daily living as usual. The levels of health-related fitness, blood lipid, and adiponectin were measured twice before and after the experiment. To analyze the statistically significance of collected data, Two-way repeated measure analysis of variance was used to determine the changes in the groups over the training period. A paired t-test was used to verify the difference within each group, and an independent t-test was used to verify the difference between the groups. In this study, the body composition including body fat mass, percent body fat and body mass index were significantly decreased in RCG compared to those in SG, and the health-related fitness showed a significant difference between RCG and SG. In addition, RCG positively modulated blood concentration of total cholesterol, triglycerides, high-density and low-density lipoprotein cholesterol. However, plasma adiponectin concentration did not show any significant differences between the two groups. Therefore, the present data suggested that resistance circuit training might be regulator to improve health-related physical fitness and decrease the level of plasma lipid in obese male college students.

The effect of combined approach of exercise training and bone marrow stromal cell (BMSC) engraftment on activation of brain-derived neurotrophic factor (BDNF)-extracellular signal-regulated kinase 1 and 2 (ERK1/2)-cyclic adenosine monophosphate response element-binding protein (CREB) signaling pathway after sciatic nerve injury (SNI) was investigated. Sixty male Sprague-Dawley rats divided into the normal control, nonexercise (NEX), exercise training (EX), BMSC transplantation (TP), and exercise training+BMSC transplantation (EX+TP) groups 4 weeks after SCI. Exercise training was carried out on the treadmill device at 5–10 m/min for 20 min for 4 weeks. Single dose of 5× 106 harvested BMSC was injected into the injury area of the injured sciatic nerve. In order to evaluate induction levels of BDNF-ERK1/2-CREB signaling molecules in the whole cell and nuclear cell lysates of the injured sciatic nerve, we applied Western blot analysis. BDNF was significantly increased only in EX+TP compared to NEX, EX, and TP groups. Phosphoinositide-dependent kinase-1 was more increased in EX, TP, and EX+TP groups than NEX group, but EX+TP group showed the most upregulation of phosphorylated protein kinase B compared to other groups. In addition, in the whole cell lysate, phosphorylated ERK1/2, but not activating transcription factor-3 (ATF-3) and phosphorylated CREB, was significantly increased in TP and EX+TP groups. In the nuclear cell lysate, ATF-3 and phosphorylated CREB were strongly activated in EX+TP group compared to EX group. Regular exercise training combined with BMSC engraftment would seem to be more effective in controlling activation of regeneration-related signaling pathway after SNI.

The purpose of this study is to investigate relationship between movement dysfunctions and sports injuries according to gender of youth soccer player. Thirty-eight middle school soccer players participated in this study and they were divided into male (n=19) and female (n=19) groups. The Functional Movement Screen (FMS) and the Quadriceps-angle (Q-angle) during single-leg squat were analyzed for identifying imbalance and asymmetry of the body, and sports injury questionnaire was examined for 6 months after FMS test. The number of sports injuries did not show significant difference between youth male and female soccer athletes. In FMS results, the scores of overhead squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, and rotary stability and the total scores were no significant differences between gender, but the score for the trunk stability push-up was significantly higher in male group than female group. There was no significant difference of Q-angle values between the left and right legs, but Q-angle value between youth male and female groups significantly showed interaction. Therefore, the present data suggested that FMS and Q-angle during single-leg squat might be indicators to predict and/or prevent sports injury in youth male and female soccer players.

Based on the earthquakes that occurred recently in Gyeongju and Pohang provinces, the Korea Peninsula needs to be prepared for a strong earthquake that might occur in the future. In this study, a strain tendency model based on the response surface method was used to analyze buried straight pipelines. The strains of the buried pipelines were computed through structural dynamics analysis, considering the section properties and ground types. In the case of the buried straight pipelines, this strain tendency model provided the necessary information for setting the strain-based design and a guideline for predicting post-earthquake damages in the Korea Peninsula.

Maternal separation during early life causes psychiatric and neurologi-cal disorders such as anxiety and depression. Depression or anxiety is closely associated with memory impairment. The purpose of this study was to investigate the effect of treadmill exercise on activity, short-term memory, vascular dysfunction using maternal separation-induced de-pression model. Maternal separation started on 15-day-old rats. The rats in the maternal separation and fluoxetine injection group received intraperitoneal injection of 5 mg/kg of fluoxetine one time daily for 15 days from 21 to 35 days. The rats performed treadmill exercise once a day during 15 days from 21 to 35 days. There was low activity and short-term memory was decreased in the maternal separation rats. Treadmill exercise and fluoxetine injection increased activity and ameliorated memory impairment. The number of rat endothelial cells antigen-1 (RECA-1) of microvessels was decreased in the maternal separation rats. The number of RECA-1was increased by treadmill exercise and fluoxetine injection. Expression of matrix metalloproteinase-9 (MMP-9) was increased and expressions of zonula occludens-2 (ZO-2) and oc-cludin were decreased in the maternal separation rats. Treadmill exer-cise and fluoxetine injection suppressed MMP-9 expression and en-hanced ZO-2 and occludin expressions in the maternal separation rats. The present study shows treadmill exercise and antidepressant treat-ment ameliorates depressive symptom and short-term memory impair-ment by protecting from blood-brain barrier damage.

Long-distance pipelines for the transport of oil and natural gas to onshore facilities are mainly fabricated by girth welding, which has been considered as a weak location for cracking. Pipeline rupture due to crack initiation and propagation in girth welding is one of the main issues of structural integrity for a stable supply of energy resources. The crack assessment should be performed by comparing the crack driving force with fracture toughness to determine the critical point of fracture. For this reason, accurate estimation of the crack driving force for pipelines with a crack in girth weld is highly required. This paper gives the newly developed J-integral and crack-tip opening displacement (CTOD) estimation in a strain-based scheme for pipelines with an internal surface crack in girth weld under axial displacement and internal pressure. For this purpose, parametric finite element analyses have been systematically carried out for a set of pipe thicknesses, crack sizes, strain hardening, overmatch, and internal pressure conditions. Using the proposed solutions, tensile strain capacities (TSCs) were quantified by performing crack assessment based on crack initiation and ductile instability and compared with TSCs from curved wide plate tests to confirm their validity.

The finite element method using the damage model has been increasingly used to predict the failure of various structures. Thus, various damage models were presented, and recently, a phenomenological model called the local fracture strain model was presented, making it easy and accurate to predict the damage of the structure. This model has the advantage of defining fracture strain as a function of stress triaxiality with only a few notched tensile tests but has a limitation because it does not consider the damage evolution because of the void growth. This study presents an enhanced damage model that improves the accuracy of the failure simulation of defected structures by adding a parameter that considers stiffness degradation according to void growth to the damage model based on the fracture strain. Therefore, loading–unloading tests were conducted and the damage index of fracture was identified using a three-dimensional digital image correlation system. The failure simulation results using the proposed damage model were compared with experimental, such as notched tensile, single edge notched tension (SENT), and full-scale burst tests.

Purpose The purpose of this study is to compare the maximal strength, isokinetic muscle function and anaerobic capacity according to the position of college and professional rugby players. Methods Subjects for this study were 54 athletes and randomly divided into 4 groups: the forwards group in college rugby players (FCRP, n = 10), backs group in college rugby players (BCRP, n = 16), forwards group in professional rugby players (FPRP, n = 16), and backs group in professional rugby players (BPRP, n = 12). Physical fitness was consisted of squat, bench press, bilateral grip strength. Isokinetic knee and trunk muscle functions were measured by Humac Norm device, and anaerobic pedaling power was analyzed by Wingate test. Significant differences between groups were determined with one-way repeated ANOVA. Results As the result of this study, there was no statistically significant difference between the absolute and relative values of the squat and bilateral grip strengths, but bench press was significantly higher in FPRP and BPRP compared to other groups. Isokinetic knee and trunk extensor and flexor muscle strength showed stronger in FPRP and BPRP than those in FCRP and BCRP. In addition, the anaerobic pedaling power was also the highest in FPRP and BPRP. Conclusions Our findings suggest important information that the college rugby players and forwards in professional rugby team should be given scientific training to improve their maximum strength, isokinetic strength and anaerobic power.

In this study, we designed mobile X-ray equipment that generates high-power X-rays, using an internal power source by means of a super-capacitor, and evaluated its safety. The proposed X-ray equipment uses the charging voltage of a battery to store high density energy, supplementing the electric charge of the super-capacitor, which can instantly release a large amount of energy. Further, pulse frequency modulation was applied to produce high voltage and thereby improve energy efficiency. The developed mobile X-ray equipment enables to generate an output of 30 kW and, therefore, can be applied to many diagnostic fields. In addition, various devices and control circuits were employed to ensure convenience and safety of using the equipment in clinical applications. This study analyzed the error ranges regarding tube voltage, tube current, irradiation time, coefficient variation, half-value layer, and the output characteristics. The results showed that the proposed X-ray equipment was able to generate 800mR X-ray power under the condition of 30 kW. The coefficient variation was less than 0.05 at all measurement points, which indicates that it is possible to generate the equal amount of X-ray when the driving conditions are same. Results also showed 51.25% of transmittance at 3.5mmAL in the case of the wire, which is thicker than a common reference of 2.3mmAL and indicates that this new mobile equipment is possible to generate X-rays with relatively high permeability. In conclusion, the findings in this study suggest that the new equipment can generate consistent high-power X-rays and, therefore, can be used safely by minimizing unnecessary re-taking of images and radiation exposure.

The purpose of this study was to investigate the effect of a stretching program, based on the Janda approach and compared with a static stretching program, on range of motion (ROM), muscle strength and pain. Subjects for this study were 11 middle-aged women with self-reported muscular skeletal symptoms. The subjects were randomly divided into six women as an experimental group (stretching based on Janda approach group, SJAG) and five women as the comparison group (traditional static stretching group, TSSG). Static stretching program in both groups consisted of 14 types of exercise and strength program in SJAG was comprised of five isometric contractions. The stretching program was performed 3 times per week for 6 weeks. The ROM and muscle strength of the neck and shoulder region were measured and a numerical rating scale was used for measuring pain. Significant differences between groups were determined with two-way repeated analysis of variance and paired t-test. As a result of this study, the ROM did not show generally significant changes but was affirmatively improved in both groups. SJAG showed significant improvement in muscle strength and pain reduction compared to the TSSG. Consequently, a stretching program based on the Janda approach would be more effective on self-reported muscular skeletal symptoms caused by posture misalignment than a static stretching program.

Crack assessment for pipe components of a nuclear power plant or oil/gas pipeline is one of the essential procedures to ensure safe operation services. To assess cracked pipes, J-integral has been considered as a theoretically robust and useful elastic-plastic fracture parameter, so that the estimations of J-integral for various pipe geometries, material properties and loading conditions are highly needed. For this reason, many engineering predictive solutions for J-estimations based on finite element (FE) analyses have been developed. Generally, many engineering predictive solutions have been suggested as a tabular-form or closed-form. Among them, the closed-form solution is more preferred than a tabular-form solution for its convenience when many lots of interpolation are required to use it. However, the accuracy of the closed-form solution tends to be significantly reduced as the number of design parameters increases. Moreover, since there is no strict rule to define the form of functions as well, the accuracy of the closed-form solution is inevitably dependent on the rule of thumb. Therefore, it is highly required to suggest a new approach for J-estimation of cracked pipes with various geometries, material properties and loading conditions. In this paper, we propose an efficient approach based on a machine learning technique to estimate J-integral for surface cracked pipes with various geometric sizes and material properties under axial displacement loading condition. Firstly, parametric FE analysis studies were systematically performed to produce the coefficients representing the engineering J-estimation for the corresponding cracked pipe. Secondly, artificial neural network (ANN) models based on deep multilayer perceptron technique were trained based on FE results. The five input neurons (pipe geometries and material properties) and the two output neurons (the coefficients representing the engineering J-estimation) were considered. Lastly, the accuracy of the trained ANN model was studied by comparing to that of the closed-form solution from multi-variable regressions.

Engineering solutions for crack-tip opening displacement (CTOD) and J-integral estimations for pipelines with a surface crack are proposed based on parametric finite element (FE) analyses for various geometries, material properties, and internal pressure conditions. Two kinds of CTOD definitions are considered in relation to strain-based estimation solutions for dealing with confusion regarding the definition of CTOD and to extend the applicability of tensile strain capacity (TSC) assessment. Moreover, influence functions of internal pressure are also suggested to take account of the effect of internal pressure on TSC. Using the proposed solutions, TSCs for cracked X65 and X70 pipes were assessed based on initiation and ductile instability. Curved wide plate tests were performed to obtain experimental TSCs, which were compared with those from the proposed solutions. Moreover, TSCs from the proposed solutions were also compared with those from other TSC-predicted models in order to assess their validity.

The purpose of this study was to investigate the effect of group jump rope exercise on health-related fitness, growth hormone (GH), and insulin growth factor-Ⅰ(IGF-Ⅰ) in male middle school students. Twenty students were randomly selected as study subjects. This study is divided into two groups: the jump rope exercise group (n=10) and the control group (n=10). The exercise group performed a 50-minute group jump rope exercise program 3 times a week for 12 weeks. And the jump rope exercise consisted of long 8-figure marathon, long 4-leap, and long hopping in and jump the roping together. The control group only performed their regular daily activities. Repeated measures ANOVA was used to analyze the difference according to the group and the exercise period. The results showed that the right grip strength and back strength in the jump rope exercise group were further increased when compared to the control group. Jump rope exercise not only significantly decreased body mass index (BMI) and body fat percentage(%BF) but also increased left grip strength, muscle endurance, cardiovascular endurance, and flexibility. In the result of the hormone analysis, jump rope exercise increased GH concentration in the blood but there is no significant between two groups. IGF-Ⅰ in the jump rope exercise group showed significant increase compared to the control group. In conclusion, this study indicates that a 12 weeks of group jump rope exercise may has positive effects on health-related fitness, GH and IGF-Ⅰ in male middle school students.

The purpose of this study was to investigate the effect of a 12-week circuit training program on health-related physical fitness and metabolic syndrome risk factors in obese female college students. Twenty subjects with over 30% of accumulated body fat voluntarily participated and were randomly allocated to the control group (n=10) or circuit training group (n=10). The circuit training program consisted of 10 types of resistance and aerobic exercise and was performed 3 times per week for 12 weeks. Health-related physical fitness and metabolic syndrome risk factors were analyzed to elucidate the effect of the circuit training. Significant differences between groups were determined with two-way repeated analysis of variance and paired t-test. As a result of this study, body weight, % body fat, and body mass index in the circuit training group was significantly decreased compared to the control group. All health-related physical fitness indicators such as back strength, sit-up, sit-and-reach, and 1,600 m running time showed relative effects between groups or over time. Among the metabolic syndrome risk factors, waist measurement, triglyceride, and total cholesterol were significantly decreased but blood glucose, high-density lipo-protein cholesterol and low-density lipoprotein cholesterol did not show any significant difference. Therefore, the present data suggested that circuit training for 12 weeks may be effective in improving physical fitness and preventing metabolic diseases.

Diabetes mellitus is associated with the impairment of sexual function including desire and orgasmic dysfunction. Sexual dysfunction in the diabetes mellitus is due to a selective defect of the nitric oxide synthase (NOS) within paraventricular nucleus (PVN). c-Fos is an immediate ear-ly gene and c-Fos expression represents neuronal activity in response to various stimuli. In the present study, we investigated the effects of treadmill exercise on sexual behaviors and the expressions of NOS and c-Fos in the PVN were evaluated using streptozotocin (STZ)-induced diabetic rats. Diabetes mellitus was induced by intraperitoneal injection of STZ. The rats in the treadmill exercise groups were made to run on a treadmill for 30 min once a day during 4 weeks. Male sexual behaviors were evaluated by recording the number of mounting, intromission, and ejaculation frequency. The present results revealed that treadmill exer-cise ameliorated sexual dysfunction in the STZ-induced diabetic rats. Treadmill exercise restored the contents of NOS and c-Fos in the PVN. The improving effect of treadmill exercise on sexual function can be considered as the neuronal activating effect of exercise through in-creasing expressions of NO and c-Fos.

Fatigue test was executed to evaluate the fatigue performance on the fillet and butt weld joint of the natural gas branch pipe. Diameter of the branch pipe, throat thickness, geometrical shape of the fillet weld and welding processes were adopted to assess the fatigue strength of the branch pipe. SMAW and GTAW process were used to compare the welding process and the mechanical performance of the fillet weld joint. API 5 L Gr. B pipe and fitting of ASTM A105 were used for the fillet weld joint. There was no difference in tensile strength with variation of the welding process of the fillet weld joint. All tensile specimens were failed at the base metal of the pipes not weld joint. Fatigue life of the fillet weld joints was improved with larger pipe diameter, the leg length of the branch pipe direction, throat thickness and area of the weld metal. Failure of the fatigue specimens were occurred at the toe or root of the fillet weld joint.

Social isolation is known to induce emotional and behavioral changes in animals and humans. The effect of treadmill exercise on depression was investigated using social isolated rat pups. The rat pups in the social isolation groups were housed individually. The rat pups in the exercise groups were forced to run on treadmill for 30 min once a day from postnatal day 21 to postnatal day 34. In order to evaluate depression state of rat pups, forced swimming test was performed. Newly generated cells in the hippocampal dentate gyrus were determined by 5-bromo-2'-deoxyuridine (BrdU) immunohistochemistry. We examined the expression of 5-hydroxytryptamine (5-HT) and tryptophan hydroxylase (TPH) in the dorsal raphe using immunofluorescence. The expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) was detected by Western blot analysis. The present results demonstrated that social isolation increased resting time and decreased mobility time. Expression of 5-HT and TPH in the dorsal raphe and expression of BDNF and TrkB in the hippocampus were decreased by social isolation. The number of BrdU-positive cells in the hippocampal dentate gyrus was suppressed by social isolation. Treadmill exercise decreased resting time and increased mobility in the social isolated rat pups. Expression of 5-HT, TPH, BDNF, and TrkB was increased by treadmill exercise. The present results suggested that treadmill exercise may ameliorates social isolation-induced depression through increasing neuronal generation.

Hydrogen usually penetrates metals through defects such as dislocations, vacancies, and crystalline imperfections and causes embrittlement, leading to cleavage fracture and intergranular fracture. Synthetic natural gas produced by coal gasification, biogas, and landfill gas inevitably contain hydrogen. Therefore, hydrogen embrittlement of pipeline materials should be considered when they are mixed with conventional natural gas and supplied to customers. To analyze hydrogen embrittlement of base metals and girth weld metals of API 5L X70 and X65 gas pipelines, a specimen was treated in 100 % hydrogen environment at 10 MPa to determine the hydrogen concentration in it. Small punch (SP) tests were performed under various gaseous components and pressures. When SP tests were performed at very low speed, hydrogen embrittlement could be observed. Specimens became very susceptible to hydrogen embrittlement with increasing hydrogen partial pressure in the hydrogen/methane gas mixture, and the SP energy also decreased dramatically.

The olfactory bulbectomy (OBX) is a well-known method inducing animal model of depression. Depression is associated with dysfunction of serotonin (5-hydroxytryptamine, 5-HT) system. In the present study, antidepressive effect of treadmill exercise was investigated using olfactory bulbectomized rats. After bilateral bulbectomy, the rats in the treadmill exercise groups were subjected to run on a treadmill for 30 min once a day during 28 days. Increased immobility time and decreased fast time in the forced swim test were observed in the olfactory bulbectomized rats. Sucrose preference in the sucrose preference test was decreased and activity in the open field test was also increased in the olfactory bulbectomized rats. Treadmill exercise decreased immobility time and activity and increased fast time and sucrose preference in the olfactory bulbectomized rats. Expressions of 5-HT and tryptophan hydroxylase (TPH) in the dorsal raphe of rats were suppressed by OBX and treadmill exercise increased the expressions of 5-HT and TPH in the olfactory bulbectomized rats. Serotonin receptor type 1A (5-HT1A) expression in the dorsal raphe was reduced by OBX and treadmill exercise increased 5-HT1A expression in the olfactory bulbectomized rats. In the present study, treadmill exercise ameliorated OBX-induced depressive symptoms. The antidepressive effect of treadmill exercise might be ascribed to the enhancement of serotonergic function through upregulation of 5-HT1A expression in the dorsal raphe.

Strain-based design assessment (SBDA) has been known for suitable assessment concept for pipelines subjected to displacement-controlled load and high plastic deformation rather than conventional stress-based design assessment. Tensile strain capacity (TSC) has been used for one of important factors to indicate limit state in strain-based design, so that it is main concern to predict accurate TSC to ensure the structural safety and integrity of pipelines. For the pipeline containing a flaw, especially a girth weld flaw, TSC based on fracture mechanics can be determined. Crack-tip opening displacement (CTOD) has been widely used for typical elastic-plastic fracture parameter, representing crack-driving force and crack-resistance curve, which are required to assess unstable crack propagation. The one of the main principles of crack assessment is that the definitions of crack-driving force and crack resistance curve should be coincident. However, there exist two kinds of the definitions of CTOD, which are based on 90° and original crack-tip concept, and these have been not unified in practical regions until now. Moreover, it is reported that the deviations of crack-resistance curve can occur in the same specimen and experiment, caused by the different definitions of CTOD. Therefore, CTOD solutions based on each of different definitions of CTOD should be highly required since inaccurate TSC would be assessed when using not the identical definition of that. In the present study, CTOD solutions of pipelines with a circumferential and internal surface flaw are suggested by using two kinds of definitions of CTOD based on 90° and original crack-tip concept. For this purpose, FE analyses were systematically carried out considering various pipe geometries and material properties. And single-edge notched tension (SENT) specimen was used for representing resistance curve of API X70/X65 material. Moreover, the effect of the choice of each CTOD definitions on TSC was investigated through crack-driving force diagram (CDFD) assessment.

The purpose of this study was to investigate differences of maximum muscle strength and isokinetic knee and core muscle functions according to pedaling power of racing cyclist candidate. Subjects for this study were 200 racing cyclist candidates and divided into four groups: top 10% peak power group (TPP, n=20), low 10% peak power group (LPP, n=20), top 10% average power group (TAP, n=20), and low 10% average power group (LAP, n=20). The maximum muscle strength was consisted of grip strength, bench press and squat measured by Ariel device, and isokinetic knee and core muscle functions were analyzed by Humac Norm device. Significant differences between groups were determined with one-way repeated analysis of variance. As the result of this study, TPP and TAP groups showed significantly decreased body-fat mass and increased free fat mass when compared to LPP and LAP groups. The maximum strength of grip and squat was significantly higher in TPP and TAP than in other groups. Isokinetic knee extension and flexion strength was higher in TPP and TAP groups as well as isokinetic trunk extension and flexion functions were highest in TPP group. Thus, our findings suggest new evidence that muscle mass, maximal muscle strength, and isokinetic muscle functions might be important predictors of racing cyclist performance.

Objective: The purpose of this study was to investigate the effect of fatigue induction on ground reactionforce (GRF) components, postural stability, and vertical jump performance in Taekwondo athletes.Method: Ten Taekwondo athletes (5 men, 5 women; mean age, 22.30 ± 2.62 years; mean height, 174.21 ±9.20 cm; mean body weight, 67.28 ± 12.56 kg) participated in this study. Fatigue was induced by a shortperiod of strenuous exercise performed on a motorized treadmill. The analyzed variables included verticaljump performance, static stability (mediolateral [ML], center of pressure [COP], anteroposterior [AP] COP,ΔCOPx, ΔCOPy, and COP area), postural stability index values (ML stability index [MLSI], AP stability index[APSI], vertical stability index [VSI], dynamic postural stability index [DPSI]), and GRF components (MLforce, AP force, peak vertical force [PVF], and loading rate). To analyze the variables measured in this study,PASW version 22.0 was used to calculate the mean and standard deviation, while a paired t-test was usedto evaluate the pre- versus post-fatigue results. Pearson``s correlation coefficients among variables were alsoanalyzed. The statistical significance level was set at α = .05.Results: Vertical jump performance decreased significantly after the induction of fatigue, while AP COP,ΔCOPx, COP area, APSI, VSI, and DPSI increased significantly. PVF and loading rate increased significantlyafter the induction of fatigue, while the postural stability variables (AP COP, ΔCOPy, COP area, APSI, VSI,DPSI) were similarly correlated with GRF components (PVF, loading rate) after fatigue was achieved (r= .600, R2 = 37%).Conclusion: These results suggest that the induction of fatigue can decrease postural stability and exerciseperformance of Taekwondo athletes during training and competition sessions.

Mobile X-ray device is widely employed because it is useful for diagnosis in patients having mobility difficulties and in medical emergencies. As various devices for X-ray generation have continued to be developed, X-ray devices can now be used more safely and effectively. However, mobile X-ray devices generate relatively low X-ray doses due to the limitation of the power input. Therefore, the use of mobile X-ray devices is limited to thin parts of body. In this study, a new device was designed in order to increase the usefulness of mobile X-ray devices by offsetting the weaknesses of the existing mobile X-ray devices, rendering them useable independently. A supercapacitor and battery were used as the internal power source for the X-ray generation in the manufactured device. The pulse width modulation (PWM) method is applied to control the tube voltage and current required for generating the X-ray, and the pulse frequency modulation (PFM) method is applied to the control to generate the high voltage in order to enhance the precision and efficiency. The manufactured X-ray device was used to evaluate the control signal, frequency, and output characteristics according to changes in tube voltage and current. Based on the results of X-ray generation, it is confirmed that precise control was achieved by X-ray generation increases linearly with increasing tube voltage and tube current. This means that precise control of the manufactured mobile X-ray device is passible. In addition, the study confirmed that stable output was achieved by checking the tube voltage, tube current and exposure rate during the exposure times by high power condition.