• Journal of Korean Physical Therapy Science
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• v.28 no.1
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• pp.76-84
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• 2021

Background: In clinical practice, active knee extension (AKE) test has been widely used to measure hamstring flexibility. During the AKE test, the knee extension is repeated six times. The first five repetitions are considered as warm-up, and the sixth is used as baseline. In order to accurately measure the subject's inherent flexibility, warm-up trials have been proposed as mentioned above; but currently, the evidence is insufficient. Design: Cross-sectional study. Methods: Forty-three healthy adults participated in this study. The AKE was performed slowly after flexing the hip and knee joints by 90° in a supine position. The knee was extended as far as could be done without causing discomfort or pain. When reaching the end range, knee flexion was performed without stopping. As per standard protocol, the subjects performed the knee extension six times. Results: There was no significant difference between the AKE value in the first trial with those in the other five trials. During the repetitions, the average value in the group with higher flexibility tended to decrease and the Intraclass correlation coefficient gradually decreased. Conclusion: Successive repetitions of the AKE test can misrepresent an individual's inherent hamstring flexibility. In order to avoid a decrease in hamstring flexibility, it is strongly recommended that individuals with high initial hamstring flexibility avoid unnecessary repetitions of the AKE test.

• Journal of Internet Computing and Services
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• v.24 no.5
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• pp.37-50
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• 2023

In general, PLL or DDS are mainly used as precise and stable frequency synthesis methods. For stable operation, a PWM frequency generation algorithm was designed and implemented using FPGA. This is an algorithm that creates a frequency 8,192 times the target frequency and then performs the D flip-flop 13 times to generate multiple frequencies with a precision of 1 Hz. Using the designed algorithm, it is applied to the Berthing system for stopping trains in station. The applied product was developed and tested against the existing operating system to confirm its superior performance in terms of frequency generation accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2203-2206
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• 2005

A load flow and short circuit fault simulation of AC electrified railway distribution systems is presented with DIgSILENT PowerFactory software. Load flow of electrified railways distribution system with concerning multi train lines and dynamic characteristics of train load is studied for different time laps. The dynamic characteristics of train load in starting and braking conditions with different starting and stopping times and its moving positions makes the load flow complicated so there is a great need in studying the effects of electrified railways on load flow. Short circuit fault transients is also studied and simulated for both power system or traction distribution system and their effects on the operation of the train sets is investigated.

• Journal of the Korean Statistical Society
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• v.25 no.2
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• pp.175-183
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• 1996

Let $S_n,n$ = 1, 2,... denote the partial sums of not necessarily in-dependent random variables. Let N(c) = min${ n ; S_n > c}$, c $\geq$ 0. Theorem 2 states that N (c), (suitably normalized), tends to 0 in p-mean, 1 $\leq$ p < 2, as c longrightarrow $\infty$ under mild conditions, which generalizes earlier result by Gut(1974). The proof follows by applying Theorem 1, which generalizes the known result $E$\mid$S_n$\mid$^p$ = o(n), 0 < p< 2, as n .rarw..inf. to randomly indexed partial sums.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.4
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• pp.363-373
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• 2014

PURPOSE: The purpose of this study was of scale using auditory biofeedback training and kinging training on walking speed and weight bearing ratio in patients hemiplegia with stroke to determine of the effects of such training would be maintained even after stopping the intervention. METHODS: The 30 subject were classified into three groups : 12 times, 3 times a week receiving the control, the experimental group scale using auditory and kicking training for 4 weeks. In addition, all subjects in the control group and experimental groups received the same general exercise treatment 12 times, 3 times a week for 4 weeks, and underwent follow-up tests. The significance of differences between the control group and the experimental groups was analysis by repeated-ANOVA, Interaction time and groups was analysis by repeated-ANOVA. In case where there were differences, post-hot tests were conducted using repeated measure ANOVA. RESULTS: There were significant differences in 10 m walking speed and weight bearing ratio between the control group and experimental group after the performance of the scale using auditory training and kicking training. Scale using auditory biofeedback training 4 weeks was more effective than kicking training. After 8 weeks weight bearing ratio maintained on scale using auditory training. CONCLUSION: These finding suggest that the scale using auditory biofeedback training and kicking training has positive effects on hemiplegia with stroke.

• Journal of Magnetics
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• v.21 no.2
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• pp.183-186
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• 2016

In this study, we report on an investigation of proton radiation resistance of 410 martensitic stainless steels under 3 MeV proton with the doses ranging from $1.0{\times}10^{15}$ to $1.0{\times}10^{17}p/cm^2$ at the temperature 623 K. Vibrating sample magnetometer (VSM) and X-ray diffractometer (XRD) were used to study the variation of magnetic properties and structural damages by virtue of proton irradiation, respectively. VSM and XRD analysis revealed that the 410 martensitic stainless steels showed proton radiation resistance up to $10^{17}p/cm^2$. Proton energy degradation and flux attenuations in 410 stainless steels as a function of penetration depth were calculated by using Stopping and Range of Ions in Matter (SRIM) code. It suggested that the 410 stainless steels have the radiation resistance up to $5.2{\times}10^{-3}$ dpa which corresponds to neutron irradiation of $3.5{\times}10^{18}n/cm^2$. These results could be used to predict the maintenance period of SUS410 stainless steels in fission power plants.

• Current Optics and Photonics
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• v.1 no.3
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• pp.186-195
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• 2017

Obtaining accurate visibility measurements is a common atmospheric optical problem, and of vital significance to civil aviation. To effectively evaluate and improve the accuracy of visibility measurements, an outdoor atmospheric simulation chamber with dimensions of $1.8{\times}1.6{\times}55.7m^3$ was constructed. The simulation chamber could provide a relatively homogeneous haze environment, in which the visibility varied from 10 km to 0.2 km over 5 hours. A baseline-changing visibility measurement system was constructed in the chamber. A mobile platform (receiver) was moved from 5 m to 45 m, stopping every 5 m, to measure and record the transmittance. The total least-squares method was used to fit the extinction coefficient. During the experiment conducted in the chamber, the unit weight variance was as low as $1.33{\times}10^{-4}$ under high-visibility conditions, and the coefficient of determination ($R^2$) was as high as 0.99 under low-visibility conditions, indicating high stability and accuracy of the system used to measure the extinction coefficients and strong consistency between repeated measurements. A Grimm portable aerosol spectrometer (PAS) was used to record the aerosol distribution, and then Mie theory was used to calculate the extinction coefficients. The theoretical results were found to be consistent with the measurements and exhibited a positive correlation, although they were higher than the measured values.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.533-538
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• 2003

It has been shown that ion implantation produces remarkable improvements in surface-sensitive physical and chemical properties as well as other mechanical properties, in polymers. In this study, ion implantation was performed onto polymer, PC(polycarbonate), in order to investigate surface hydrophilic property through contact angle measurement using distilled water. PC was irradiated with N, Ar, Xe ions at the irradiation energy of $20\;{\sim}\;50keV$ and the dose range of $5{\times}10^{15},\;1{\times}10^{16},\;7{\times}10^{16}\;ions/cm^2$. The contact angle of water has been reduced with increasing fluence and ion mass but increased with increasing implanted energy. The changes of chemical and structural property are discussed in view of infrared spectroscopy and FT-IR, XPS, which shows increasing C-O bonding and C-C bonding. The root mean square of surface roughness examined by means of AFM changed smoothly from 0.387nm to 0.207nm and the change of wettability was discussed with respect to elastic and inelastic collisions obtained as results of TRIM simulation. It was found that wettability of the modified PC surface was affected on change of functional group and nuclear stopping or linear energy transfer(LET, energy deposited per unit track length per ion) that causes chain scission by displacing atom from polymer chains, but was not greatly dependant on surface morphology.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1492-1501
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• 2006

A transportation system of single wafer has been developed to be applied to semiconductor manufacturing process of the next generation. In this study, the experimental apparatus consists of two kinds of track, one is for propelling a wafer, so called control track, the other is for generating an air film to transfer a wafer, so called transfer track. The wafer transportation speed has been evaluated by the numerical and the experimental methods for three types of nozzle position a..ay (i.e., the front-, face- and rear-array) in an air levitation system. Test facility for 300mm wafer has been equipped with two control tracks and one transfer track of 1500mm length from the starting point to the stopping point. From the present results, it is found that the experimental values of the wafer transportation speed are well in agreement with the computed ones. Namely, the computed values of the maximum wafer transportation speed $V_{max}$ are slightly higher than the experimental ones by about $15{\times}20%$. The disparities in $V_{max}$ between the numerical and the experimental results become smaller as the air velocity increases. Also, at the same air flow rate, the order of wafer transportation speeds is : $V_{max}$ for the front-array > $V_{max}$ for the face-array > $V_{max}$ for the rear-array. However, the face-array is rather more stable than any other type of nozzle array to ensure safe transportation of a wafer.

• Journal of the Korean Mathematical Society
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• v.50 no.5
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• pp.1129-1163
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• 2013

Based on finite element discretization, two linearization approaches to the defect-correction method for the steady incompressible Navier-Stokes equations are discussed and investigated. By applying $m$ times of Newton and Picard iterations to solve an artificial viscosity stabilized nonlinear Navier-Stokes problem, respectively, and then correcting the solution by solving a linear problem, two linearized defect-correction algorithms are proposed and analyzed. Error estimates with respect to the mesh size $h$, the kinematic viscosity ${\nu}$, the stability factor ${\alpha}$ and the number of nonlinear iterations $m$ for the discrete solution are derived for the linearized one-step defect-correction algorithms. Efficient stopping criteria for the nonlinear iterations are derived. The influence of the linearizations on the accuracy of the approximate solutions are also investigated. Finally, numerical experiments on a problem with known analytical solution, the lid-driven cavity flow, and the flow over a backward-facing step are performed to verify the theoretical results and demonstrate the effectiveness of the proposed defect-correction algorithms.