• Proceedings of the KSME Conference
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• 2008.11a
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• pp.368-371
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• 2008

An extensometer system to measure strain and displacement of cylindrical fatigue specimen in a autoclave of high temperature and high pressure environment has been developed by KEPRI. The extensometer reads the displacement caused by fatigue loads at the target length of the specimen installed inside the autoclave. The performance of the extensometer were tested at 15MPa, $315^{\circ}C$ of a operating pressurized water reactor. Two LVDT's of magnet type were connected to the extensometer and used for converting the fatigue displacement to electronic signal. The device is being used for developing environmental fatigue curve of CF8M cast austenitic stainless steel (CASS) in the test condition of low cycle and low strain. This paper introduces the background and results of the development.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.19-21
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• 2005

The ball shea. tests for ball grid array (BGA) and flip chip packages were carried out with different displacement rates to find out the optimum condition of the displacement rate for this test. The BGA packages consisted of two different kinds of solder balls (eutectic Sn-37wt.%Pb and Sn-3.5wt.%Ag) and electroplated Au/Ni/Cu substrate, whereas the flip chip package consisted of electroplated Sn-37Pb solder and Cu UBM. The packages were reflowed up to 10 times, or aged at 443 K up to 21 days. The variation of the displacement rate resulted in the variations of the shear properties such as shear force, displacement rate at break, fracture mode and strain rate sensitivity. The increase in the displacement rate led to the increase of the shear force and brittleness of solder joints.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10a
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• pp.293-298
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• 2001

N-value is usually used to assume the displacement depth of embankment on the soft marine clay. But N-value of the soft marine clay tend to underestimate unlike overestimating of general cases. In general case, if the length of rod is more long then N-value is more large because it is under the influence of energy loss of hammer blow. So it is reasonable to correct N-value down. But in the case of soft marine clay, N-value must not be correct down. Especially to assume the displacement depth of embankment on the soft marine clay, it must be used laboratory test results or CPT, Vane Test than N-value. In this study, it is compared with two field cases that design displacement method of embankment.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.13-20
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• 2023

Purpose : The purpose of this study is to compare the balance ability between subjects with chronic ankle instability and normal people and the center of pressure displacement during the sit to stand and stand to sit. Methods : The subjects of this study were 63 who met the inclusion criteria and were classified into normal group (n=33) and chronic ankle instability group (n=30). The displacement of the center of pressure during sit to stand and stand to sit was measured. And the limit of stability and Y-balance tests were performed to measure the balance ability. Independent t-test was conducted to compare center of pressure displacement and balance ability between groups, and pearson correlation was conducted to analyze the correlation between the center of pressure displacement and balance ability. Results : In the case of the center of pressure displacement, there was a significant difference between the two groups during sit to stand and stand to sit. In the case of balance, both limit of stability and Y-balance test showed significant differences between the two groups. At the time of sit to stand, the center of pressure displacement showed a significant correlation with balance abilities, and at the time of stand to sit, the center of pressure displacement showed a significant correlation with Y-balance test. Conclusion : Chronic ankle instability shows that there is a lot of sway in the body due to compensation to replace the decrease in ankle joint range of motion when performing sit to stand and stand to sit due to sensory input damage such as decrease in ankle range of motion and decrease in ankle proprioception. Chronic ankle instability is expected to have a negative effect on our daily lives in life. The results of this study will serve as the basis for the dynamic approach to objective evaluation, treatment, and prevention of chronic ankle instability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.10
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• pp.813-820
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• 2021

In this study, a low-velocity impact test was performed to obtain the dynamic properties of solid propellants. The dynamic behavior of the solid propellant was examined by measuring the force and displacement of the impactor during the low-velocity impact test. The bending displacement was calculated by compensating for the local displacement caused by the low-velocity impact test in the form of three point bending and the shear displacement caused by using a short and thick solid propellant specimen. Stress and strain were calculated using compensated displacements and measured force, and dynamic properties of solid propellants were obtained from the stress-strain curve and compared with static bending test. The dynamic properties of solid propellant under the low-velocity impact loading at various operating temperature conditions such as room temperature(20 ℃), high temperature(63 ℃), and low temperature(-32 ℃) were compared and investigated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.184-185
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• 2014

The purpose of this study is to experimentally evaluate the variation characteristics of stiffness and impact resistance under the construction height of gypsum board wall at the actual construction site. The method suggested in previous study was applied on the test method of horizontal load resistance and impact resistance. As a result of horizontal load resistance test, when the wall height is 2,400 mm, the maximum displacement is 13.6 mm and residual deformation is 0.5 mm, and when the wall height is 3,000 mm, the maximum displacement is 31.3 mm and the residual displacement is 6.8 mm. As a result of impact resistance test, the residual deformation of each specimen at 20 cm of fall height were 1.02 mm and 0.08 mm, respectively, the residual deformation at 40 cm of fall height were 1.58 mm and 0.35 mm, respectively, and the residual deformation at 60 cm of fall height were 2.23 mm and 2.48 mm, respectively.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.221-228
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• 2003

The stress corrosion index of Kumamoto andesite are evaluated by two types of testing method. One is the uniaxial compression test under various water vapor pressures, and the other is the double torsion (DT) test under a constant water vapor pressure. For the uniaxial compression tests, the uniaxial compressive strength increases linearly with decreasing water vapor pressure on the double logarithmic coordinates. As the results, the stress corrosion index obtained is estimated 44. On the other hand, in the DT test, the relaxation (RLX) test and the constant displacement rate (CDR) test were conducted. For the CDR test, as the displacement rate of loading point increases, the crack velocity increases. However, the fracture toughness is constant regardless of the change in displacement rate and the average fracture toughness is evaluated $2.07MN/m^{3/2}$. For the RLX test, the crack velocity-stress intensity factor curves are smooth and linear. The stress corrosion index estimated from the curves is 37. Comparing stress corrosion indexes in the uniaxial compression test and the DT test, there is no significant difference in these values, and they are considered to be in coincident each other regardless of testing methods. Therefore, it is concluded that stress corrosion is one of material constants of rock.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.72-78
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• 2009

We have developed a current range extension method to obtain the ratio error and phase displacement of a current transformer (CT) by using absolute evaluation method and two different CTs. The method was applied to CTs under test with the current ratios in the range of 5,000 A / 1 A - 20,000 A / 1 A. The ratio error and phase displacement of the CT under test obtained in this study are consistent with those measured at the national institute in Germany using the same CT under test within an expanded uncertainty (k = 2) in the overall current ratios.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.555-562
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• 2005

In this study, we tried to establish the method of evaluating the tensile properties of the ring specimen of Arsene which have gauge length. In this result, we verified the availability of central piece. We made ring specimens and devices such as central piece, pins, and clevises. A proper tensile speed was determined by pre-test. The result of main test was calibrated and compared with the result of FEM. To obtain the tensile properties from the ring test result, we observed two relationships: one is strain-displacement and the other is load ratio-displacement. The tensile properties could be evaluated by using these relationships.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.754-759
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• 2008

Recently, the construction of buildings and large bridges has been increasing rapidly causing foundation structure growing larger then before, especially in the use of large size cast-in-place piles. Barrette Pile will usually be used at the site where diaphragm wall is the retaining wall to save time and cost in mobilization of equipments. This study uses bi-directional loading test data obtained from two different sites to observe the bearing capacity and displacement characteristics of barrette pile. Numerical analysis of the test is done by using commercial 3D computer program and the interface effect and capacity of the pile as well as displacement characteristics of the pile is verified.