• Communications of the Korean Mathematical Society
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• v.34 no.1
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• pp.105-111
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• 2019

Let $Y{\subset}{\mathbb{P}}^3$ be a degree d reduced curve with only planar singularities. We prove that $h^i({\mathcal{I}}_Y(t))=0$, i = 1, 2, for all $t{\geq}d-2$. We use this result and linkage to construct some triples (d, g, s), $d>s^2$, with very large g for which there is a smooth and connected curve of degree d and genus g, $h^0({\mathcal{I}}_C(s))=1$ and describe the Hartshorne-Rao module of C.

• Journal of the Korean Mathematical Society
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• v.34 no.1
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• pp.43-55
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• 1997

Suppose that D is a domain in the extended complex plane $\overline{C} = C \cup {\infty}$. For each $z_0 \in C$ and $C < r < \infty$, we let $B(z_0, r) = {z \in C : $\mid$z - z_0$\mid$ < r}$ and $S(z_0, r) = \partial B(z_0, r)$. For non-empty sets A, $B \subset \overling{C}$, diam (A) is the diameter of A and d(A, B) is the distance of A and B.

• East Asian mathematical journal
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• v.40 no.1
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• pp.75-83
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• 2024

For a reduced, irreducible and nondegenerate curve C ⊂ ℙ^r of degree d, it was shown that the arithmetic genus g of C has an upper bound π₀(d, r) by G. Castelnuovo. And he also classified the curves that attain the extremal value. These curves are arithmetically Cohen-Macaulay and contained in a surface of minimal degree. In this paper, we investigate the arithmetic genus of curves lie on a surface of minimal degree - the Veronese surface, smooth rational normal surface scrolls and singular rational normal surface scrolls. We also provide a construction of curves on singular rational normal surface scroll S(0, 2) ⊂ ℙ³ which attain the maximal arithmetic genus.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1707-1714
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• 2016

Let $C{\subset}{\mathbb{P}}^r$ be a nondegenerate projective curve of degree d > r + 1 and of maximal regularity. Such curves are always contained in the threefold scroll S(0, 0, r - 2). Also some of such curves are even contained in a rational normal surface scroll. In this paper we study the minimal free resolution of the homogeneous coordinate ring of C in the case where $d{\leq}2r-2$ and C is contained in a rational normal surface scroll. Our main result provides all the graded Betti numbers of C explicitly.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.222-227
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• 2004

Under cyclic loading, the fatigue failures of welded joints occur at weld toes which induce stress concentration by weld shape. So we need to obtain the peak stress and the S-N curve to assess the fatigue strength of welded joints. However the measurement of peak stress is of high uncertainty and low reproducibility, so we use nominal stress instead in fatigue tests of welded joints. In this study, fatigue tests to obtain S-N curves and FE analyses to obtain stress concentration factors were conducted for the two types of cruciform fillet welded joints, that is, load-carrying and non load-carrying types. Then we changed the obtained S-N curves to that based on peak stress using the hot-spot stress concept. From the analyses of the S-N curves obtained, we have concluded that there is a need to develop a new method to evaluate the fatigue life.

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1387-1395
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• 2016

To investigate the dynamic strain aging (DSA) behavior of Alloy 617, high-temperature tensile tests were carried out with strain rates variations of $10^{-3}/s$, $10^{-4}/s$, and $10^{-5}/s$ from $24^{\circ}C$ to $950^{\circ}C$. Five flow relationships, Hollomon, Ludwik, Swift, Ludwigson, and Voce, were applied to describe the tensile true stress-strain curves, and the DSA region was defined. In describing the tensile curves, Ludwigson's equation was superior to the other equations, and the DSA region was adequately defined by this equation as plateaus at intermediate temperatures from $200^{\circ}C$ to $700^{\circ}C$. It was identified that Alloy 617 is dominated by three types of serrations, known as Types D, A+B, and C. The activation energy values for each serration type were obtained by the Arrhenius equation. By using the obtained activation energy values, the serrated yielding map and the DSA mechanism were drawn and manifested. In addition, the relationship between the tensile strength and strain rate at higher temperatures above $700^{\circ}C$ was found to be closely related to the amounts of slip lines. In the scanning electron microscope (SEM) fractographs, there was a significant difference at the low, intermediate, and high temperatures, but almost the same to the three strain rates.

• The Journal of Engineering Geology
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• v.30 no.1
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• pp.59-69
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• 2020

Pull-out load tests were performed on a CPR (Compaction grouting compound Pile with Reinforce) test pile, with skin friction being evaluated by the yield load and allowable bearing capacity after analyzing load-displacement curves and load-settlement curves. Results of the CPR test piles analyzed from the load-displacement curves show that the yield load and allowable bearing capacity of the large-diameter CPR test pile were about 1.4 times larger than that of the small-diameter pile. Results of the load-settlement curves reveal that the allowable bearing capacity of the CPR test pile with diameter of D500 was 1.2~2.1 times greater than that of the pile with diameter of D400. However, the allowable bearing capacity calculated using Fuller's analysis differed substantially from that determined using the P (Pull-out load) - S (Settlement) and log P - log S curves. Therefore, calculation of the allowable bearing capacity using Fuller's analysis is shown to be inappropriate.

• Computers and Concrete
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• v.4 no.3
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• pp.221-241
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• 2007

Based on the experiment results, the damage and fracture behavior of concrete at the ages of 1d, 2d, 7d and 28d, in three-point bending and uniaxial tensile tests, were simulated with a finite element program, ABAQUS. The critical stress intensity factor $K_{IC}^s$ and the critical crack tip opening displacement ($CTOD_C$) of concrete were calculated with effective-elastic crack approach for the three-point bending test of grade C30 concrete. Based on the crack band model, a bilinear strain-softening curve was derived to simulate the LOAD-CMOD curves and LOAD-Displacement curves. In numerical analysis of the uniaxial tension test of concrete of grade C40, the damage and fracture mechanics were combined. The smeared cracking model coupling with damaged variable was adopted to evaluate the onset and development of microcracking of uniaxial tensile specimen. The uniaxial tension test was simulated by invoking the damage plastic model which took both damage and plasticity as inner variables with user subroutines. All the numerical simulated results show good agreement with the experimental results.

• Earthquakes and Structures
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• v.25 no.3
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• pp.199-208
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• 2023

Seismic performance analysis is one of the fundamental steps in the design of new or retrofitting buildings. In the seismic performance analysis, the adapted spectral acceleration curve for a given site mainly governs the seismic behavior of buildings. Since every soil site (class) has a different impact on the spectral accelerations of input motions, different spectral acceleration curves have to be involved for every soil class that the building is located on top of. Modern seismic design codes (e.g., Eurocode 8, EC8, or Turkish Building Earthquake Code, TBEC) provide design response spectra for all the soil classes to be used in the building design or retrofitting. This research aims to evaluate the EC8 and TBEC based design response spectra using the spectra of real earthquake input motions that occurred (and were recorded at only soil classes A, B and C, no recording is available at soil class D) in a specific area in Turkey. It also conducts response spectrum analyses of 5, 10 and 13 floor reinforced concrete building models under EC8, TBEC and actual spectral response curves. The results indicate that the EC8 and especially TBEC given design response spectra cannot be able to represent the mean actual spectral acceleration curves at soil classes A, B and C. This is particularly observed at periods higher than 0.3 s, 0.42 s and 0.55 s for the TBEC design response spectra, 0.54 s, 0.65 s and 0.84 s for the EC8 design response spectra at soil classes A, B and C, respectively. This is also reflected to the shear forces of three building models, as actual spectral acceleration curves lead to the highest shear forces, followed by the shear forces obtained from EC8 and, then, the TBEC design response spectra.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.242-249
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• 2002

This research suggests the assessment method of the additional lateral force caused bending moment of CWR when a freight car loading it is passing over turnout system or curves. The characteristics of lateral lone are analyzed by calculating the lateral pressure acting on the rails of conventional railway.