• Journal of Ocean Engineering and Technology
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• v.28 no.4
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• pp.306-313
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• 2014

Super duplex stainless steels (sDSS) are excellent for use under severely corrosive conditions such as offshore and marine applications like pipelines and flanges. sDSS has better mechanical properties and corrosion resistance than the standard duplex stainless steel (DSS) but it is easier for a sigma phase to appear, which depresses the mechanical property and corrosion resistance, compared to DSS, because sDSS has a higher alloy element than DSS. In addition, sDSS has a feeble ductile-brittle transition temperature (DBTT) because it has a 50% ferrite microstructure. In the actual operating environment, sDSS would be thermally affected by welding and a sub-zero temperature environment. This study analyzed how precipitated sDSS behaves at a sub-zero temperature through annealing heat treatment and a sub-zero tensile test. Six types of specimens with annealing times of up to 60 min were tested in a sub-zero chamber. According to the experimental results, an increase in the annealing time reduced the elongation of sDSS, and a decrease in the tensile test temperature raises the flow stress and tensile stress. In particular, the elongation of specimens annealed for 15 min and 30 min was clearly lowered with a decrease in the tensile test temperature because of the increasing sigma phase fraction ratio.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.2
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• pp.61-66
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• 2002

This study was carried out to investigate sheet properties of Indian mallow hanji, made by different pulping methods such as alkali and sulfomethylated pulpings, and different stock compositions, various mixing ratios of bast fiber and woody core fibers. Effect of morphological properties of pulp stocks on the sheet formation and their optical properties were also evaluated using an image analyzer and confocal laser scanning microscope(CLSM). In addition, the effect of fiber distribution index(FDI), which was calculated based on the image in a z-direction of a sheet from CLSM, on the sheet properties of Indian mallow hanji was discussed. The proposed FDI had a good correlation with various properties of paper, such as apparent density, opacity, tear index, breaking length and zero-span tensile strength. Especially, sulfomethylated pulp sheets＇FDI was higher than alkali pulp sheets.

• East Asian mathematical journal
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• v.22 no.1
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• pp.53-59
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• 2006

We introduce the resistant length and examine its properties. And consider the applications of resistant length to the boundary behavior of conformal mappings. We obtain the theorems in the connection with the resistant length zero and the fundamental sequences. The method of resistant length leads a simple proofs of theorems.

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.267-277
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• 2011

This paper is concerned with eigenvalues of second-order vector equations on time scales with boundary value conditions. Properties of eigenvalues and matrix-valued solutions are studied. Relationships between eigenvalues of different boundary value problems are discussed.

• Journal of the Chungcheong Mathematical Society
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• v.26 no.1
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• pp.243-248
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• 2013

In this paper, we introduce the mathematical resistance and examine its properties and consider the applications of mathematical resistance to conformal mappings. We obtain the theorems in the connection with "the mathematical resistance zero" and "the fundamental sequences".

• Honam Mathematical Journal
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• v.22 no.1
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• pp.31-36
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• 2000

In this paper, we introduce the extremal length and examine its properties and consider the applications of extremal length to conformal mappings. We obtain the theorems in the connection with "the extremal length zero" and "the fundamental sequences".

• Honam Mathematical Journal
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• v.27 no.1
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• pp.1-8
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• 2005

Let R be a commutative ring with non-zero identity. This paper is devoted to the study some of properties of the product of submodules of a multiplication module. Suppose N is a submodule of a multiplication R-module M. We give a condition which allows us to determine whether N is finitely generated when we assume some power of N is finitely generated.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.121-124
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• 2000

적응 학습 알고리즘으로 가중치를 변화시키는 단층 신경망의 출력부에 Ramp 임계 함수를 적용하여 입력이 zero-mean Gaussian random vector인 경우 가중치의 stationary point를 구하고, 적응 학습 알고리즘을 유도한다.

• Journal of Elementary Mathematics Education in Korea
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• v.22 no.2
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• pp.183-198
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• 2018

In this paper, I theoretically considered joining and separating activities and revisited the textbooks from 7 countries and Korean mathematics textbooks from 5th revised curriculum to 2015 revised curriculum to find implication for the treatment of 0 in the joining and separating activities. The 'joining' has definition and properties similar to addition, but the 'separating'is difficult to define and is not considered to have properties similar to subtraction. In the sense of computation, joining and separating can be seen as' part-part-to-whole' situations, but are just part of the addition and subtraction situations. The analysis of textbooks from 7 counties showed that Singapore and Malaysia textbooks already studied zero and then included it in joining and separating activities, but other countries did not include it as joining and separating activities. The textbooks of South Korea have consistently suggested not to include zero, but teacher's guide has shown that there is a little consistency in the treatment of zero. As a conclusion, I suggested that it was necessary to propose a proper context of the situation in order to introduce joining and separating without including 0 in terms of student level and to propose that a more consistent presentation of zero handling in the teaching in the teacher's guide.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.665-668
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• 2008

Portland cement production-1.5billion tonnes yearly worldwide-contributes substantially to global atmospheric pollution($\sim$7% of total of CO$_2$ emissions). Attempts to increase the utilization of fly ash, a by-products from thermal power plant to partially replace the cement in concrete are gathering momentum. But most of fly ash is currently dumped in landfills, thus creating a threat to the environment. Therefore, In this study, influence of curing temperature(30, 60, 90$^{\circ}$C) on the strength of properties fly ash based cement ZERO mortar was investigate, measured a weight change and pH change according to each care of curing temperature. The test results that a curing at 90$^{\circ}$C is appropriate in case of the high strength concrete is required in the early-age of the curing and 60$^{\circ}$C is efficient for the case of requiring high strength at age 28 days. Furthermore pH variation and value of compressive strength are judged to correlate but change of weight is not the case.