• 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 Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.335-336
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• 2018

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.471-472
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• 2005

After thermal aging treatment at 693 K for 322 hours, any discernable precipitation could not be found in the $13{\sim}22$ Cr ODS steels, but showing an increase in SP-DBTT and reduction in upper shelf energy. The degree of aging embrittlement increases with Cr content such that the increases in SP-DBTT are 10, 50 and 73 K in 13, 16 and 19 Cr ODS steel, respectively. Amount of hardening also increased linearly as a function of Cr content. Based on the TEM observation, the origin of hardening must be related to the invisibly fine size of Cr-rich ${\acute{\alpha}}-phase$ (<1 nm).

• BMB Reports
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• v.40 no.5
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• pp.708-714
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• 2007

The two-component signal transduction, which typically consists of a histidine kinase and a response regulator, is used by bacterial cells to sense changes in their environment. Previously, the SphS-SphR histidine kinase and response regulator pair of phosphate sensing signal transduction has been identified in Synechocystis sp. PCC 6803. In addition, some response regulators in bacteria have been shown to be cross regulated by low molecular weight phosphorylated compounds in the absence of the cognate histidine kinase. The ability of an endogenous acetyl phosphate to phosphorylate the response regulator, SphR in the absence of the cognate histidine kinase, SphS was therefore tested in Synechocystis sp. PCC 6803. The mutant lacking functional SphS and acetate kinase showed no detectable alkaline phosphatase activity under phosphate-limiting growth conditions. The results suggested that the endogenous acetyl phosphate accumulated inside the mutants could not activate the SphR via phosphorylation. On the other hand, exogenous acetyl phosphate could allow the mutant lacking functional acetate kinase and phosphotransacetylase to grow under phosphate-limiting conditions suggesting the role of acetyl phosphate as an energy source. Reverse transcription PCR demonstrated that the transcripts of acetate kinase and phospho-transacetylase genes in Synechocystis sp. PCC 6803 is up-regulated in response to phosphate limitation suggesting the importance of these two enzymes for energy metabolism in Synechocystis cells

• Journal of the Korean institute of surface engineering
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• v.46 no.5
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• pp.229-233
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• 2013

The small punch(SP) tests that can be applied to high strength sheet steel in automobile were carried out to evaluate the behavior of hydrogen embrittlement of DP sheet steels. In order to charge hydrogen at DP sheet steels, DP sheet steels were treated by the electrochemical hydrogen charging method under the charging conditions of current densities of 100, 150 and 200 $mA/cm^2$ for charging times of 5, 10, 25 and 50 hrs. Respectively, After hydrogen charging with experimental conditions, SP tests were performed. From the SP results, the correlations between the variation of bulb diameters and bulb heights with the hydrogen charging conditions were analysed. It was shown that the variation of bulb diameters were not significant with the hydrogen embrittlement due to the amounts of hydrogen charging. On the other hand, the bulb heights were observed to decrease with increasing hydrogen contents. It was thought that these results of the variation of bulb shapes after SP tests would be estimated as the index of evaluation of hydrogen embrittlement.

• The Korean Journal of Mycology
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• v.28 no.2
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• pp.97-102
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• 2000

The mycelial growth of Pleurotus ostreatus in compost is strongly stimulated by solid-state fermentation with thermophilic fungi which were isolated from oyster mushroom compost. The biochemical characteristics of these thermophilic fungi were investigated. Cellulase and ligninase activities were not detected by clear zone effect on CMC and lignin media. All of thermophilic fungi grew well with high mycelial density on xylan media and the growing rate of Sepedonium sp. S-2 observed very high. In results of MUF-test, extracellular enzyme activity of Sepedonium sp. S-2, and S-5 measured very high. On the compost after high temperature fermentation with Sepedonium sp. S-2 and S-5, the mycelial growing rate of Pleurotus ostreatus was increased about 50% and it also showed the inhibiting effect on mycelial growth of Trichoderma sp. SJG-51. Isolated thermophilic fungi, Sepedonium sp. S-2 and S-5 were expected as very useful organism for making oyster mushroom compost.

• Journal of the Korean Electrochemical Society
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• v.25 no.4
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• pp.162-173
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• 2022

The development of new materials is an essential key for unraveling the environmental and energy problems all over the world. Among the various application materials in this area, crystalline and two-dimensional carbon materials have been studied from points of view such as electrical conductivity, chemical stability, and surface engineering due to the assembly of honeycomb and sp/sp² hybridization structure. Novel two-dimensional materials, including graphene and graphyne, have been continuously reported for several decades to develop in renewable energy fields. Also, various pristine/engineered two-dimensional carbon allotropes have been researched to combine metal nanoparticles in the form of a sphere, cubic, and so on. The renewable energy performance to apply for these materials is drastically increased. In this review, we introduce the research points of the 2D carbon allotrope materials, graphene and graphyne, and applications to improve the performance of renewable energy applications.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.239-240
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• 2017

• Geophysics and Geophysical Exploration
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• v.21 no.4
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• pp.231-243
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• 2018

Streaming potential (SP) arises from fluid flow through effectively connected pores. From this potential, formation water information as well as fluid flow properties can be estimated. As micro particles being located in boundary between subsurface porous media and fluid are charged to form electrical double layer, fluid flow caused by several reasons generates SP, one of electrokinetic phenomena. Occurrence mechanism of SP is complex and signal strength is relatively weak compared to noise. However, application of self potential survey using SP to monitoring of formation fluid is expanding because of its' convenience of exploration without artificial source and repetitiveness of signal. This paper accounts for the occurrence mechanism of SP studied before, including governing equations and analyzes previous various case studies of SP according to the change of physical properties of materials. It helps to increase understanding about SP and also lays the foundations of the application of SP to fields.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.299-300
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• 2017