• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2565-2573
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• 2002

A basic research was performed to ensure the usefulness of Small Punch-creep(SP-creep) test for residual life evaluation of heat resistant components effectively. This paper presents analytical results of initial stress and strain distributions in SP specimen caused by constant loading for SP-creep test and its experimental correlations with uniaxial creep(Ten-creep) test on 9Cr1MoVNb steel. It was shown that the initial maximum equivalent stress, ${\sigma}_{eq{\cdot}max}$ from FE analysis was correlated with steady-state equivalent creep strain rate, ${\epsilon}_{qf-ss'}$ rupture time, $t_r$, activation energy, Q and Larson-Miller Parameter, LMP during SP-creep deformation. The simple correlation laws, ${\sigma}_{sp}-{\sigma}_{TEN}$, $P_{sp}-{\sigma}_{TEN}\; and\; Q_{sp}-Q_{TEN}$ adopted to established a quantitative correlation between SP-creep and Ten-creep test data. Especially, the activation energy obtained from SP-creep test is linearly related to that from Ten-creep test at $650^{\circ}C$ as follows : $Q_{SP-P}\;{\risingdotseq}\;1.37 \;Q_{TEN},\; Q_{SP-{\sigma}}{\risingdotseq}1.53\; Q_{TEN}$.

• Journal of Welding and Joining
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• v.16 no.6
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• pp.35-43
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• 1998

In this paper, the fracture toughness evaluation of the various microstructures such as HAZ, F.L and W.M in weldment of TMCP steel which has the softening zone owing to high heat input welding was carried out by using of the small punch(SP) test. In addition, the fracture toughness with the specimen orientation of rolled TMCP steel was investigated by means of SP test and the crack opening displacement (COD) test and then was compared with that of conventional SM50YB steel. From the results of SP test for TMCP steel, it could be seen that the SP energy transition curves of three different orientation were shifted to higher temperature side in order of S, T and L. But the {TEX}$DBTT_{SP}${/TEX} of each orientation specimen did not show a lot of differences and were quite lower than those of conventional SM50YB steel. The mechanical properties of HAZ structure in weldment of TMCP steel such as hardness, SP energy at room temperature and -196$^{\circ}C$ and the upper shelf energy of SP energy transition curve were lower than those of base metal due to softening. The {TEX}$DBTT_{SP}${/TEX} of each microstructure in weldment of TMCP steel increased in order of HAZ, F.L and W.M against base metal, but all microstructures showed a quite lower {TEX}$DBTT_{SP}${/TEX} than those of SM50YB steel.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.1995-2001
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• 2001

In this study, a small punch creep(SP-Creep) test using miniaturized specimen(10${\times}$10${\times}$0.5mm) is described to develop the new creep test method for high temperature structural materials. The SP-Creep test is applied to 2.25Cr-lMo(STBA24) steel which is widely used as boiler tube material. The test temperatures applied for the creep deformation of miniaturized specimens are between 550∼600$^{\circ}C$. The SP-Creep curves depend definitely on applied load and creep temperature, and show the three stages of creep behavior like in conventional uniaxial tensile creep curves. The load exponent of miniaturized specimen decreases with increasing test temperature, and its behavior is similar to stress exponent behavior of uniaxial creep test. The creep activation energy obtained from the relationship between SP-Creep rate and test temperature decreases as the applied load increases. A predicting equation or SP-Creep rate for 2.25Cr-lMo steel is suggested. and a good agreement between experimental and calculated data has been found.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.105-110
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• 2000

The Micromechanics test is new test method which uses comparatively smaller specimen than that required in conventional material tests. There are several methods, such as small-specimen creep test, the continuous indentation test, and small punch(SP) test. Among them, the small punch(SP) test method has been applied to many evaluation fields, such as a ductile-brittle transition temperature, stress corrosion cracking, hydrogen embrittlement, and fracture properties of advanced materials like FGM or MMC. In this study, the small punch(SP) test is performed to evaluate the mechanical properties at high/low temperature from $-196^{\circ}C$ to $650^{\circ}C$ and the material degradation for virgin and aged materials of 9Cr1MoVNb steel which has been recently developed. The ${\Delta}P/{\Delta}{\delta}$ parameter defined a slope in plastic membrane stretching region of SP load-displacement curve decreases according to the increase of specimen temperature, and that of aged materials is higher than the virgin material in all test temperatures. And the material degradation degrees of aged materials with $630^{\circ}C$ -500hrs and $630^{\circ}C$ -1000hrs are $36^{\circ}C$ and $38^{\circ}C$ respectively. These behaviors are good consistent with the results of hardness($H_v$) and maximum displacement(${\delta}_{max}$).

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.21-26
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• 2011

Type-3 cylinder liner has a limitation of machining the standard specimen for fracture toughness test because it has approximately 5 mm in thickness as well as a curvature. Hence, it needs to be employed a miniature specimen test technique to evaluate fracture toughness of the cylinder liner. In this study, small punch (SP) test method was employed to evaluate fracture toughness of the cylinder liner. Load-displacement curve result measured from the SP test showed that the liner material was failed during membrane stretching in the general SP load-displacement curve. Additionally, it was shown that liner material was isotropic although the amount of plastic deformation was different depending on the direction due to manufacturing process characteristics. Fracture toughness, $J_{Ic}$, was evaluated using the SP test data. The value of fracture toughness obtained was $13.0kJ/m^2$. This value was similar to that of the same kind of materials. Therefore, the fracture toughness evaluated using the SP test data was reasonable.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.111-116
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• 2001

Small punch-creep(SP-Creep) test technique has been applied for evaluating the creep characteristics for high temperature materials. However, in order to evaluate the damage and predict the remaining life, it is necessary to establish a quantitative correlation between SP-Creep and uniaxial-creep test results. This paper presents analytical and experimental results of useful correlation between SP-Creep and uniaxial-creep properties for 9Cr1MoVNb steel at $600{\sim}650^{\circ}C$ in terms of stress(load) and activation energy during creep deformation. Especially, the activation energy obtained from SP-Creep test is linearly related to that from uniaxial-creep test at $650^{\circ}C$ as follows: $Q_{sp-p}{\fallingdotseq}1.37\;Q_{TEN},\;Q_{sp-{\sigma}}{\fallingdotseq}1.53\;Q_{TEN}$.

• Journal of Welding and Joining
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• v.7 no.4
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• pp.56-67
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• 1989

In this study, the possibility of evaluating the peculiar fracture strength of weldment in high strength steels was investigated by means of a small punch(SP) test. In order to obtain the ductile-brittle transition temperature(DBTT) of SP energy by which the fracture strength of weldment in structural steels such as SS41 and SM53B steels had been evaluated in our preceding publication, the effects of notches and loading rates on SP energy were discussed. It was found that the correspondence of SP energy to critical COD at test temperature -196.deg. C showed a linear relation with some deviation. The empirical correlation with scatter band, Esp/(Esp)p = 1.67[.delta./(.delta./sub c//(.delta./sub c/)/sub p/]-0.55, was developed between the SP energy ratio and critical COD ratio of each weld structure compared with parent material at test temperature -196.deg. C. In addition, there did not appear to be a significant effect of test materials and specimen size etc. on the correlation.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.43-48
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• 2000

In this study, a small punch creep(SP-Creep) test using miniaturized specimen$(10{\times}10{\times}0.5mm)$ has been described for the development of the newly semi-destructive creep test method for high temperature structural components such as headers and tubes of boiler turbine casino and rotor and reactor vessel. The SP-Creep testing technique has been applied to 2.25Cr-1Mo(STBA24) steel used widely as boiler tube material and the creep test temperature are varied at $550^{\circ}C{\sim}600^{\circ}C$. The overall deformations of SP-Creep curves are definitely depended with applied load and creep test temperature and show the creep behaviors of three steps like conventional uniaxial creep curves. The steady state creep rate${\delta}_{ss}$ of SP-Creep curve for miniaturized specimen increases with increasing creep temperature, but the exponential value with creep loading is decreased. The activation energy$(Q_{spc})$ during SP-Creep deformation with various test temperatures shows 605.7kJ/mol that is g.eater than 467.4kJ/mol reported in uniaxial creep test. This may be caused by the difference of stress states during creep deformation In two creep test. But from the experimental results, e.g. SP-Creep curve behaviors, the steady state creep rate${\delta}_{ss}$ with creep temperature, and the exponential value(n) with creep loading, it can be summarized that the SP-Creep test may be a useful test method to evaluate the creep properties of the heat resisting material.

• Journal of Korean Academy of Nursing
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• v.34 no.2
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• pp.324-332
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• 2004

Purpose: The purpose of this study was to explain differences of cesarean section rates according to San- Yin-Jiao(SP6) acupressure for women in labor. Method: A noneqivalent control group pre test - post test design was used to explain differences of cesarean section rates according to SP6 acupressure. The participants were 209 women who were assigned to one of three groups SP6 acupressure(n=86), SP6 touch(n=47), and control group(n=76). For 30 minutes, the SP6 acupressure group received SP6 acupressure, and the SP6 touch group received SP6 touch for the duration of each uterine contraction. The Control group was encouraged to deep breath and relax for the duration of each uterine contraction for 30 minutes. Result: The rates of cesarean section were 12.8%, 29.8%, and 22.4% for the SP6 acupressure group, SP6 touch group, and control group respectively. There was a significant difference among groups (p=0.049). Cesarean section rateswere significantly different between the SP6 acupressure and non-SP6 acupressure group(p=0.035). Conclusion: This finding shows that 30 minutes of SP6 acupressure was effective in decreasing the cesarean section rate. Therefore, SP6 acupressure during labor could be applied as an effective nursing intervention.

• Journal of The Korean Dental Society of Anesthesiology
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• v.12 no.1
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• pp.17-23
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• 2012

Background: This study evaluated pulp vitality of anterior permanent teeth using pulse oximetry (PO), which is already used for monitoring of patient's $SpO_2$ and pulse rates (PR). Also we compared with ice tests and electric pulp test (EPT). Methods: 9 teeth, endodontic treated, were selected as non-vital teeth group. 17 vital teeth were selected as control group. Our aim is to compare sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of ice test, electric pulp test and pulse oximetry, respectively. Pulse oximetry has two test results, $SpO_2$ and pulse rates. Also we calculated correlation and statistical significances by Pearson's test between EPT and pulse oximetry. Results: Sensitivity, specificity, PPV, NPV were calculated on each tests. Ice test has results of 1.00, 0.89, 0.94 and 1.00, respectively. EPT has results of 0.94, 0.78, 0.89 and 0.88 respectively. $SpO_2$ has results of 0.94, 1.00, 1.00 and 0.90, respectively. PR has results of all 1.00. Conclusions: PO showed relatively accurate, stable and objective results on both $SpO_2$ and PR. Percentage of ability of accurate diagnosis for vital teeth is 94% for ice test, 89% for EPT, 100% for $SpO_2$ and PR. Percentage of ability of accurate diagnosis for non-vital teeth is 100% for ice test, 88% for EPT, 90% for $SpO_2$ and 100% for PR. In additions, PR could be more accurate and significant tests than $SpO_2$.