• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3046-3051
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• 2011

The third-rail system is an important device supplying power directly to the Maglev train through physical contact with the collecting shoe. It is directly related to safety and reliability for the running of Maglev. However, most the third-rail system used in Korea depend on foreign product or technologies, Korea Urban Maglev in the development of appropriate power feeding is urgent. In particular, the turnout section is the weakness point in the system because bending force by turnout section movement and fatigue caused by repetitive motion as well as the expansion by temperature, the forces by Maglev collecting shoe is added th the third-rail. Therefore, this paper proposes the third-rail system appropriate for Korean Urban Maglev of turnout section. To verify the structural stability of POSCO ICT third-rail system, the finite element analysis and physical testing was performed. The third-rail is fixed on each side of the turn-out section steel structure by epoxy insulation supporter and the integral behaviors are occurred. Therefore, the maximum horizontal displacements of each support are investigated and then, it is applied to finite element model of the third-rail to investigate the moments and stress. Also, the bending test about one million times and Expansion Joint for the third-rail was performed. The third-rail system safety and reliability was identified by test line on Korea Institute of Machinery & Materials in Deajeon for under the actual usage environment such as the Maglev and turn-out operation.

• Physical Therapy Korea
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• v.5 no.4
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• pp.41-51
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• 1998

The right hip abductor musculature has been reported to demonstrate "stretch weakness" attributable to chronic elongation imposed by standing posture common to right-handed healthy persons. Kendall and associates have described the concept of "stretch weakness",. The purpose of this study was to assess isometric hip abduction torque and surface electromyographic activity (using MYOMED 432) in a sample of 40 healthy right-handed persons (20 male, 20 female), all of whom agreed to participate in the study, and compare side difference in the hip abductor musculature. In order to assure the statistical significance of the results, the paired t test was applied at the .05 level of significance. The results were as follows: 1) The difference in apparent leg length of right and left legs was significant at the .05 level. 2) There was a significant difference between right and left pelvic height (standing position) at the 05 level measurements, and scapula height at the .05 level. 3) Power measurements and action potentials of right hip abductor were greater than the left hip abductor regardless of the range of joint motion (inner range, outer range) 4) The difference in muscle power and action potentials according to inner or outer range of both hip abductor were significant at the .05 level. 5) In supine during active left hip abduction, the appearance of action potentials in the right hip abductors is indicative of contra-lateral effect (p<.05) These results suggest: In healthy right-handed persons, the apparent leg length on the right is longer than on the left, and pelvic height is elevated on the right side. Muscle those and muscle action potentials of the right hip abductor are higher than those of the left hip abductor in the lengthened position. Therefore, the results in this study are contrary to Kendall's. This type of study should be carried out in many physical therapy departments.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.6
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• pp.538-546
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• 2015

This paper describes an intelligent ankle assistive robot which provides assistive power to reduce ankle torque based on an analysis of ankle motion and muscle patterns during walking on level and sloped floors. The developed robot can assist ankle muscle power by driving an electric geared motor at the exact timing through the use of an accelerometer that detects gait phase and period, and a potentiometer to measure floor slope angle. A simple muscle assistive link mechanism is proposed to convert the motor torque into the foot assistive force. In particular, this mechanism doesn't restrain the wearer's ankle joint; hence, there is no danger of injury if the motor malfunctions. During walking, the link mechanism pushes down the top of the foot to assist the ankle torque, and it can also lift the foot by inversely driving the linkage, so this robot is useful for foot drop patients. The developed robot and control algorithm are experimentally verified through walking experiments and EMG (Electromyography) measurements.

• Archives of Reconstructive Microsurgery
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• v.10 no.2
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• pp.111-117
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• 2001

Introduction : The Functional muscle transfer is used to reconstruct the injuried muscle and paralysis of the shoulder. Especially transfer of the trapezius has been the treatment of choice but it has disadvantages of inadequate function and deformed contour, and instability of humeral head in case of acromion resection. We report an operation for shoulder reconstruction after wide resection of malignant fibrous histiocytoma, using rotational latissimus dorsi flap and review the operation method and clinical outcome. Materials and Methods : A patient, 53 year old, with malignant fibrous histiocytoma in the acromioclavicular joint area had been underwent wide excision, including the deltoid, clavicular head of pectoralis major, part of trapezius, lateral 1/3 of clavicle and acromion including scapular spine. The rotational latissimus dorsi flap with its neurovascular pedicle was dissected and then placed over the resected area and transfer of muscle attached at coracoid process was done to achieve stability of the humeral head. The range of motion of the shoulder and test of muscle power were evaluated for functional outcome. Total follow-up period is 2 years 11 months. Results : At last follow-up, the range of motion of the shoulder is abduction $90^{\circ}$, flexion $90^{\circ}$, internal rotation $40^{\circ}$, external rotation $50^{\circ}$ and the muscle power is 4 grade in all direction and then we obtained good functional results. There are no complications such as instability or subluxation of the humeral head and deformed contour and he is a disease-free survival state. Conclusions : The transfered latissimus dorsi flap provides adequate lever arm and stabilization and covering of the humeral head by sufficient muscle volume and width. This procedure can be useful not only for the paralysed deltoid reconstruction but also for use in reconstructive surgery after wide resection of the shoulder for malignant tumor.

• Laser Solutions
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• v.7 no.2
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• pp.1-10
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• 2004

This work was attempted to join SCP sheet and STS304 sheet by using Nd:YAC laser beam. SCP sheet has good formability and low cost, while STS304 has excellent corrosion resistance and mechanical properties in high temp. In this experiment, butt joint type was used to develop the tailored blank welding for dissimilar steel. Sheets which have different thermal properties. Computer simulation was conducted to obtain the off-set position for efficient welding by considering laser power, scanning speed, focal length and basic properties. The result showed that the optimum thermal distribution was obtained when the laser beam was irradiated at $0.05{\sim}0.1$ mm off-set toward the SCP sheet side. The experiment was conducted based on the result of computer simulation to show the same optimum conditions. Optimum conditions were 3KW in laser beam power, 6m/min in scanning speed, -0.5mm in focal position, 0.1mm off-set toward SCP. Microhardness test, tensile test, bulge test, optical microscopy, EDS, and XRD were performed to observe the microstructure around fusion zone and to evaluate the mechanical properties of optimum conditions, The weld zone had high microhardness values by the formation of the martensitic structure. Tensile test measured the strength of welded region by vertical to strain direction and the elongation of welded region by parallel to strain direction. Bulge test showed $52\%$ formability of the original materials. Bead shape, grain size, and martensitic structure were observed by the optical microscopy in the weld zone. Detailed results of EDS, XRD confirmed that the welded region was connected of martensitic structure.

• New & Renewable Energy
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• v.16 no.1
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• pp.47-57
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• 2020

In Floating PV (Photovoltaic) systems, PV modules are installed on water by utilizing the surface of idle water such as a reservoir and multipurpose dam. A floating PV system, therefore, has the advantage of efficiency in national land use and improved energy yield owing to cooling effect compared to on-land PV systems. Owing to the limitation of installation environment for a floating PV system, the system, however, has the disadvantage of an increase in transmission distance of DC (Direct current) cables. A longer transmission distance of a DC cable results in greater power loss due to a voltage drop. This leads to a decline in economic feasibility for the floating PV system. In this paper, the economic analysis for 10 floating PV systems installed in a reservoir has been conducted in terms of a change in annual power sales according to the variation of transmission losses depending on the factors affecting the voltage drop, such as transmission distance, cross-section area of underwater cable, the presence of joint box, and PV capacity.

• The Journal of Korean Physical Therapy
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• v.15 no.2
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• pp.168-181
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• 2003

The purpose of this study was to investigate the effects of circuit weight training(CWT) on isokinetic muscle strength and body composition in elderly. The subjects who engaged in this experiment exercised at 40$\%$ of 1-RM, 12 repetitions, followed by 15 sec as the subject moved to the each break training program which was consist of the circuit of 10 stations performed on 3 set a day, circuits 3 days a week during 10 weeks. The assessment of isokinetic factor was in concentric flexors and extensors of right and left knee joint. Tests were performed on the Cybex 770 Isokinetic Dynamometer and body composition were estimated the three parts of chest, abdomen and anterior thigh by using skinfold caliper, calculated the average and followed by Seri and Brozek way. Statistical analysis were performed using analysis of variance paired t-test, accepting level for all significant was above $\alpha$=.05 and $\alpha$=.01. Following is as a result of 10 weeks circuit weight training. 1. At the $60_{\circ}$ /sec, the right and left knee isokinetic concentric flexors and extensors peak torque increased significantly (p < .01). 2. At the $180_{\circ}$ /sec, the right and left knee isokinetic concentric flexors and extensors peak torque increased significantly (p < .01). 3. At the $60_{\circ}$ /sec, the right and left knee isokenetic concentric flexors and extensors average power increased significantly(p < 0.5, p < .01) and at the $180_{\circ}$ /sec, the right extensors didn't show any statistical significant. 4. At the $60_{\circ}$ /sec, the right and left knee Isokinetic concentric flexors and extensors total work increased significantly(p < .05, p < .01) but at the $180_{\circ}$ /su right concentric flexors didn't show any statistical significant. 5. The body composition changed significantly(p < .01). These results suggest that 10 weeks circuit weight training increases the peak torque, average power, total work significantly and decreases the $\%$body fat significantly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1125-1134
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• 2013

Small cells such as pico or femto cells are promising as a solution to cope with higher traffic explosion and the large number of users. However, the users within small cells are likely to suffer severe inter-cell interference (ICI) from neighboring base stations (BSs). To tackle this, several papers suggest BS transmit power on/off control algorithms which increase edge user throughput. However, these algorithms require centralized coordinator and have high computational complexity. This paper makes a contribution towards presenting fully distributed and low complex joint BS on/off control and user scheduling algorithm (FDA) by selecting on/off pattern of BSs. Throughput the extensive simulations, we verify the performance of our algorithm as follows: (i) Our FDA provides better throughput performance of cell edge users by 170% than the algorithm without the ICI management. (ii) Our FDA catches up with the performance of optimal algorithm by 88-96% in geometric average throughput and sufficiently small gap in edge user throughput.

• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.778-791
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• 2005

A novel pneumatic artificial muscle actuator (PAM actuator), which has achieved increased popularity to provide the advantages such as high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks, has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. However, some limitations still exist, such as the air compressibility and the lack of damping ability of the actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. Then it is not easy to realize the performance of transient response of pneumatic artificial muscle manipulator (PAM manipulator) due to the changes in the external inertia load with high speed. In order to realize satisfactory control performance, a variable damper-Magneto­Rheological Brake (MRB), is equipped to the joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control method brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity, uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control method and without regard for the changes of external inertia loads.

• Geomechanics and Engineering
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• v.16 no.1
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• pp.21-34
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• 2018

Discontinuities considerably affect the mechanical and hydraulic properties of rock mass. These properties of the rock mass are influenced by the geometry of the discontinuities to a great extent. This paper aims to render an account of the geometrical parameters of several discontinuity sets related to the surrounding rock mass of Rudbar Lorestan Pumped Storage Power Plant powerhouse cavern making use of the linear and areal (circular and rectangular) sampling methods. Taking into consideration quite a large quantity of scanline and the window samplings used in this research, it was realized that the areal sampling methods are more time consuming and cost-effective than the linear methods. Having corrected the biases of the geometrical properties of the discontinuities, density (areal and volumetric) as well as the linear, areal and volumetric intensity accompanied by the other properties related to four sets of discontinuities were computed. There is an acceptable difference among the mean trace lengths measured using two linear and areal methods for the two joint sets. A 3D discrete fracture network generation code (3DFAM) has been developed to model the fracture network based on the mapped data. The code has been validated on the basis of numerous geometrical characteristics computed by use of the linear, areal sampling methods and volumetric method. Results of the linear sampling method have significant variations. So, the areal and volumetric methods are more efficient than the linear method and they are more appropriate for validation of 3D DFN (Discrete Fracture Network) codes.