• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1702-1707
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• 2007

The reduction of pipe-thickness induced by flow accelerated corrosion (FAC) is one of the most serious problems on the maintenance of piping system in nuclear power plants (NNP). If the thickness of a pipe component is reduced below the critical level, it cannot sustain pressure and consequently results in leakage or rupture. For this reason, wall thinning by FAC has been inspected in secondary side piping systems in NPPs. In this research Round Robin Test (RRT) was conducted to verify confidence of wall thinning measurement system in NPP. 12 inspectors from 3 companies participated and 23 specimens were used according to standard practice in RRT. The gage R&R analysis was introduced in regard to repeatability and reproducibility that are affected to measurement system errors. Confidence intervals of thickness measurement system were obtained.

• Journal of Welding and Joining
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• v.31 no.1
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• pp.21-25
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• 2013

Aluminum alloy, Al5083-O, is one of candidate materials for the LNG storage tank, because of its excellent weldability, cryogenic characteristics, and corrosion resistance. The good weldability of Al5083-O is very important in LNG storage tank manufacturing. In this study, high current metal inert gas(MIG) welding process was used to get one pass welding of thick plate aluminum alloy. Bead on plate(BOP) welding was performed to evaluate the effect of welding conditions on the height of bead and depth of penetration. The optimum welding conditions were derived to get one pass welding of the thickness of 14.5mm. The mechanical properties of the welded joint were evaluated. The cross-sectional macro test, tensile test, and bending test satisfied the class rule.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.181-184
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• 2003

The Four-Ball Tester has been widely used as a tool to charaterize lubricity for long time. In order to understand more acurate properties of lubricants, more test methods have been developed. Among the test methods, SRV test method was compared to Four-Ball Tester in this paper.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.180-186
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• 2001

The condensation heat transfer coefficients of pure refrigerants R-22, R-134a, and a binary refrigerant mixture R-410A flowing in a small diameter tube were investigated. The experiment apparatus consists of a refrigerant loop and a water loop. The main components of the refrigerant loop consist of a variable-speed pump, a mass flowmeter, an evaporator, and a condenser(test section). The water loop consists of a variable-speed pump, an isothermal tank, and a flowmeter. The condenser is a counterflow heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus. The test section consists of smooth, horizontal copper tube of 3.38mm outer diameter and 1.77mm inner diameter. The length of test section is 1220mm. The refrigerant mass fluxes varied from 450 to 1050kg/(㎡$.$s) and the average inlet and outlet qualities were 0.05 and 0.95, respectively. The main results were summarized as follows ; in the case of single-phase flow, the heat transfer coefficients increase with increasing mass flux. The heat transfer coefficient of R-410A was higher than that of R-22 and R-134a, and the heat transfer for small diameter tubes were about 20% to 27% higher than those predicted by Gnielinski. In the case of two-phase flow, the heat transfer coefficients also increase with increasing mass flux and quality. The condensation heat transfer coefficient of R-410A was slightly higher than that of R-22 and R-134a. Most of correlations proposed in the large diameter tube showed significant deviations with experimental data except for the ranges of low quality and low mass flux.

• Journal of Magnetics
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• v.19 no.2
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• pp.192-196
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• 2014

The aim of the present study was to examine the effects of high and low frequency repetitive transcranial magnetic stimulation on motor cortical excitability and the balance function in subacute stroke patients. Twenty-four subjects were randomly assigned to either the high frequency (HF) rTMS group, or the low frequency (LF) rTMS group, with 12 subjects each. All subjects received routine physical therapy. In addition, both groups performed a total of 20 sessions of rTMS for 20 minutes, once a day, 5 times per week, for a 4-week period. In the HF rTMS group, 10 Hz rTMS was applied daily to the hotspot of the lesional hemisphere; and in the LF rTMS group, 1 Hz rTMS was applied daily to the hotspot of the nonlesional hemisphere. Motor cortex excitability was determined by motor evoked potentials, and the balance function was evaluated by use of the Balance Index (BI) and the Berg Balance Scale (BBS), before and after the intervention. The change rate in the value of each variable differed significantly between the two groups (p<0.05). Furthermore, significant differences were observed between all post-test variables of the two groups (p<0.05). In the HF rTMS, significant differences were found in all the pre- and post-test variables (p<0.05). On the other hand, in the LF rTMS, significant difference was observed only between the pre- and post-test results of BI and BBS (p<0.05). The findings demonstrate that HF rTMS can be more helpful in improving the motor cortical excitability and balance function of patients with subacute stroke treatment than LF rTMS, and that it may be used as a practical adjunct to routine rehabilitation.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.5
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• pp.835-842
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• 2020

This paper considers a method of reproducing abnormal and fault operation for smart monitoring of thrust bearing used in wave power generation system. In order to develop smart monitoring technology, abnormal and failure data of actual equipment are required. However, it is impossible to artificially break down the actual equipment in operation due to safety and cost. To tackle this problem, a test bed that can secure data through reproduction of a faulty operating environment should be developed. Therefore, in this study, test bed that can reproduce each situation was developed and the operation result was analysis after identifying the situation to be reproduced through the failure factor analysis of the thrust bearing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1371-1375
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• 2005

The paper has analyzed the influence of tire design variable on the tire Force and Moment (F&M) characteristics, especially by the belt angle, the Plysteer Residual Aligning Torque (PRAT) which is considered as one of the causing factors for the vehicle pull. To validate the tire FE model, the tire stiffness and the PRAT which can be derived from the simulation data have been compared with the experimental data of test machine. In addition to PRAT characteristic, the tire stiffness and cornering characteristics due to the belt angle have been investigated. The effects of drum's curvature on the PRAT have been also investigated using the tire FE model and the usefulness of the current drum type F&M test machine can be confirmed.

• Geomechanics and Engineering
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• v.29 no.5
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• pp.487-496
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• 2022

Most of the pile's vertical static load tests in construction sites are the proof load tests, which is difficult to accurately estimate the ultimate bearing capacity and analyze the reliability of piles. Therefore, a reliability analysis method based on the proof load-settlement (Q-s) data is proposed in this study. In this proposed method, a simple ultimate limit state function based on the hyperbolic model is established, where the random variables of reliability analysis include the model factor of the ultimate bearing capacity and the fitting parameters of the hyperbolic model. The model factor M = R_uR / R_uP is calculated based on the available destructive Q-s data, where the real value of the ultimate bearing capacity (R_uR) is obtained by the complete destructive Q-s data; the predicted value of the ultimate bearing capacity (R_uP) is obtained by the proof Q-s data, a part of the available destructive Q-s data, that before the predetermined load determined by the pile test report. The results demonstrate that the proposed method can easy and effectively perform the reliability analysis based on the proof Q-s data.

• Natural Product Sciences
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• v.15 no.3
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• pp.115-120
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• 2009

Woohwangcheongsimwon (WHCSW) is a traditional oriental medicinal fomula which has been clinically used for treating strokes, palpitation, loss of consciousness and anxiety. The purpose of this study was to characterize the putative anxiolytic properties of WHCSW using an elevated plus-maze (EPM) and hole-board test. Control mice were orally treated with an equal volume of vehicle (10% Tween 80 solution), and positive control mice were treated with diazepam (1 mg/kg, i.p.). In the EPM test, WHCSW significantly increased the percentage of time-spent in the open arms (200 mg/kg, P < 0.05) and the percentage of open arm entries (200 and 400 mg/kg, P < 0.05). WHCSW also significantly increased the number of head-dips in the hole-board test (200 mg/kg, P < 0.05). In addition, the anxiolytic properties of WHCSW examined in the EPM test were inhibited by flumazenil (10 mg/kg, i.p.), a GABA$_A$ antagonist. However, no changes in spontaneous locomotor activity or myorelaxant effects were observed versus 10% Tween 80 controls. These results suggested that WHCSW is an effective anxiolytic agent, and that its anxiolytic effects are mediated via GABA$_A$ receptors.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.183-191
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• 2008

This study evaluated influence of the loading head dimension on characteristics of deformation strength ($S_D$) of asphalt mixtures. Kim test and Wheel tracking (WT) test were conducted to evaluate $S_D$ characteristics with relation to WT results for various mixtures. The $S_D$ values and coefficient of variation of $S_D$ values of r=10mm were smaller than those of r=10.5mm. It was also found that $S_D$ values obtained using r=10mm loading head showed high correlations with rut parameters of WT test. It was indicated that the aggregate size and radius (r) of round cut were statistically significant variables on $S_D$ at = 0.05 level in the analysis of variance. However, in interaction of r and aggregate size showed no significance within $10{\sim}19mm$ aggregate size at the same level. Therefore, it was concluded that the diameter (D) of 40mm and the bottom edge radius (r) of 10mm was suitable dimension of loading head for deformation strength test.