• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.47-54
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• 2019

The purpose of this study was to investigate the effect of visual conditions on the static balance of stable and unstable surfaces. Thirty healthy adults participated in this study (13 men, 17 women). Visual conditions were set as vertical, horizontal, and diagonal. It was performed on the pad to measure the balance on the unstable support surface. Using the balance measuring instrument, the General Stability Index, Weight Distribution Index, and Weight Distribution was measured. Paired t-tests were used for ground-based comparisons and one-way ANOVAs were used for comparisons within the same ground. The general stability index showed a significant difference according to the horizontal and vertical line directions on the stable support surface(p<.05). According to the comparison between the grounds, the weight distribution index on the unstable support surface showed a significant difference(p<.05). Weight distribution showed significant differences between the left and right eyes on the support surface with the stable and the unstable horizontal visual condition(p<.05). In static balance training, vertical and diagonal visual direction conditions are predicted to be helpful for training.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.6
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• pp.654-661
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• 2005

Copper is a well known alloying element that is used to improve the resistance to general corrosion of stainless steel And also Cu cation have the anti-fouling effect to inhibit adhesion of the marine algae and shellfish to the surface of heat exchanger cooling pipe or outside wall of the ship, Therefore there are some anti-fouling methods such as anti-fouling Paint mixed with copper oxide or MGPS(Marine Growth Preventing System) by using Cu cation dissolved to the sea wather solution. Cu cation can be dissolved spontaneously by galvanic current due to Potential difference between Cu and cooling pipe of heat exchanger with Ti material, which may be one of the anti-fouling designs. In this study the effect of annealing heat treatment to galvanic current and Polarization behavior was investigated with a electrochemical points of view such as measurement of corrosion Potential, anodic polarization curve. cyclic voltammetric curve, galvanic current etc The grain size of the surface in annealed at $700^{\circ}C$ was the smallest than that of other annealing temperatures. and also the corrosion Potential showed more positive potential than other annealing temperatures. The galvanic current between Ti and Cu with annealed at $700^{\circ}C$ was the largest value in the case of static condition. However its value in the case of flow condition was the smallest than the other temperatures. Therefore in order to increase anti-fouling effect by Cu cation, the optimum annealing temperature in static condition of sea water is $700^{\circ}C$, however non- heat treated specimen in the case of flow condition may be desirable.

• The Journal of Korean Physical Therapy
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• v.31 no.4
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• pp.176-183
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• 2019

Purpose: The purpose of this study was to investigate the short term effects of ASEJ (ankle strengthening with emphasis on jumping) for 3weeks on strength, mechanical properties, and balance and to compare the balance with and without HH(high-heel) condition. Methods: ASEJ (a combined exercise of squat, heel raise up, and jumping) were performed for the subjects in 11 female ankle instability young females ($21.7{\pm}2.0yrs$ Cumberland ankle instability score $19{\pm}6.5$). To investigate the effect of ASEJ, investigator used dynamometer for measuring strength, MyotonPRO for measuring mechanical properties(tone, stiffness, and elasticity of the muscles), I-Balance test for static balance, and Y-balance test for dynamic balance between the condition with and without HH condition. All data were normally distributed and analyzed using the SPSS 22.0 statistical program. Comparing pre- and post-intervention and the condition with and without HH conditions data were examined using the paired t-test. The level of significance was chosen as 0.05 for all the analyses. Results: 3wks of ASEJ would strengthen leg muscles and increasing muscle tone and stiffness in most muscles however there was decreasing muscle elasticity of gastrocnemious. In addition, the ASEJ improves the static balance for ankle instability young females and increases the dynamic balance when wearing the heels especially. Conclusions: the ASEJ could recommend to improve the strength and balance for ankle instability young females. Also, measuring the balance with HH conditions well represents the risk of ankle damage in female.

• Nuclear Engineering and Technology
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• v.39 no.2
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• pp.123-128
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• 2007

In order to apply a static fault-tree (FT) method to a system or a plant whose configuration changes dynamically, condition gates and a post processing method are used to effectively accommodate these changes. An operator's performance change, which can be caused by these configuration changes, should also be considered to assess the risk to a plant in a more realistic manner. This study aims to develop an integrated framework to accommodate various configuration changes and their effect on an operator’s performance by using the FT model. We applied a condition-based human reliability assessment (CBHRA) method to consider various conditions endured by an operator. That is, we integrated the CBHRA method with the conventional post processing method for modeling the system configuration changes. The effect of the condition monitoring systems installed in a plant is also considered. In this study, we show an example application of the integrated framework to a probabilistic safety assessment for the shutdown phase of a nuclear power plant.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.11
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• pp.895-900
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• 2005

We derive a linear matrix inequality(LMI) condition guaranteeing that any invariant zeros of a triple (A, B, C) lie in the open left half plane of the complex plane, i.e. $C(sI-A)^{-1}B$ is minimum phase. The LMI condition is equivalent to a certain constrained Lyapunov matrix equation which can be found in many results relating to stability analysis or control design. We show that the LMI condition can be used to simplify various control engineering problems such as a dynamic output feedback control problem, a variable structure static output feedback control problem, and a nonlinear system observer design problem. Finally, we give some numerical examples.

• The Journal of Korean Physical Therapy
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• v.27 no.5
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• pp.292-298
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• 2015

Purpose: The purpose of this study was to examine the effects of dual tasks on balance and postural control during standing in patients with cerebellar ataxia (CA). It was hypothesized that CA patients would exhibit different sway characteristics of the center of mass (COM) depending on the complexity of the secondary cognitive tasks compared with normal control subjects. Methods: A total of 8 patients with CA and age-matched healthy control subjects participated in this study. They were instructed to perform two balance tasks (non-dual and dual movement) with 3 different complexity of dual tasks. Range, variability, and velocity of COMs were measured. Results: According to the results CA patients showed deficits in balance and postural control with increased dual-task complexity during the static balance task in saggital sway movements. However, there was no significant difference in static balance in frontal sway. With higher difficulty in the cognitive task, CA patients took longer to stabilize their body center, while normal control subjects showed no change between conditions. In addition, CA patients had a greater COM resultant velocity during recovery in the dual-task condition compared with the single-task condition. These findings indicate that CA patients had defendable compensatory strategies in performing dual tasks. Conclusion: In conclusion, CA patients appeared to manage the priority to balance and postural control. Particularly in a situation with a postural threat such as when potential consequences of the loss of stability increase, they appeared to prioritize the control of balance and posture over the performance of the secondary task.

• Journal of Energy Engineering
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• v.20 no.2
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• pp.154-162
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• 2011

PMT(Preventive Maintenance Template) is a standardized maintenance program that describes maintenance items & period as operation condition to increase component reliability at the component level. The existing maintenance programs are focused on time based maintenance to inspect and repair component depend on fixed period. But recently, we have developed advanced maintenance program(named PMT) to increase reliability and optimize maintenance program of the plant significant component. This paper presents how to develop the PMT for nuclear power plant's static exciter.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.1
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• pp.84-91
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• 2011

A finite element analysis for the wing and landing gear of a composite target-drone air vehicle was performed. For the wing analysis, two load cases were considered: a 5g symmetric pull-up and a -1.5g symmetric push-over. For the landing gear analysis, a sinking velocity of 1.4 m/s at a 2g level landing condition was taken into account. MSC/NASTRAN and LS-DYNA were utilized for the static and dynamic analyses, respectively. Finite element results were verified by the static test of a prototype wing under a 6g symmetric pull-up condition. The test showed a 17% larger wing tip deflection than the finite element analysis. This difference is believed to come from the material and geometrical imperfections incurred during the manufacturing process.

• KIEAE Journal
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• v.7 no.4
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• pp.141-146
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• 2007

It is necessary to guarantee the safety, serviceability and durability of reinforced concrete structures over their service life. However, concrete structures represent a decrease in their durability due to the effects of external environments according to the passage of time, and such degradation in durability can cause structural degradation in materials. In concrete structures, some degradations in durability increase the corrosion of embedded rebars and also decrease the structural performance of materials. Thus, the structural condition assessment of RC materials damaged by corrosion of rebars becomes an important factor that judges needs to apply restoration. In order to detect the damage of reinforced concrete structures, a visual inspection, a nondestructive evaluation method(NDE) and a specific loading test have been employed. However, obscurities for visual inspection and inaccessible members raise difficulty in evaluating structure condition. For these reasons, detection of location and quantification of the damage in structures via structural response have been one of the very important topics in system identification research. The main objective of this project is to develope a methodologies for the damage identification via static responses of the members damaged by durability. Six reinforced concrete beams with variables of corrosion position and corrosion width were fabricated and the damage detections of corroded RC beams were performed by the optimization and the conjugate beam methods using static deflection. In results it is proved that the conjugate beam method could predict the damage of RC members practically.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.4
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• pp.361-369
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• 2002

In order to extract motion features from an input image acquired by a static CCD-camera in a restricted area, we need a robust algorithm to cope with noise sensitivity and condition change. In this paper, we proposed an efficient algorithm to extract and track motion features in a noisy environment or with sudden condition changes. We extract motion features by considering a change of neighborhood pixels when moving objects exist in a current frame with an initial background. To remove noise in moving regions, we used a morphological filter and extracted a motion of each object using 8-connected component labeling. Finally, we provide experimental results and statistical analysis with various conditions and models.