• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.113-119
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• 1985

The fatigue strength and reliability of concrete subjected to ftexural loading is investigate. The concrete beam specimens are prepared and tested in four-point flexural loading in which the bottom fiber stress varies from zero to a predetermined maximum stress. The S-N curves are generated from these test results and an equation is obtained by regression analysis to predict the flexural fatigue strength of concrete. A method is presented to perform the probabilistic analysis on the flexural fatigue of concrete. It is shown that the Weibull distribution has physically more convincing features and may be appropriate to describe the fatigue behavior of concrete.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.3
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• pp.112-124
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• 2017

As an LNG carrier preserves and transports liquefied natural gas under minus $163^{\circ}C$, the cargo tank has to have sufficient hull strength against not only the wave loads but also against loads caused by loading and unloading and thermal expansion to keep the LNG safely. The main insulation types for a CCS are No.96 and Mark III from GTT for the membrane LNG carrier. Particularly, the invar membrane plate in No.96 is very thin and its connections could experience high local stresses owing to such dynamic loads. Therefore, it should be verified whether those connections have sufficient fatigue lives for the purpose of operation and maintenance. This research aims at performing fatigue analysis with 0.1 fatigue damage criteria for 40 years of design life to support new membrane CCS development using proper S-N curves and the associated finite element modeling technique for each connection and then propose a reasonable design methodology.

• Structural Engineering and Mechanics
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• v.24 no.5
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• pp.585-599
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• 2006

This paper describes a series of laboratory tests carried out to evaluate the influence of bed joint orientation on interlocking grouted stabilised mud-flyash brick masonry under uniaxial cyclic compressive loading. Five cases of loading at $0^{\circ}$, $22.5^{\circ}$, $45^{\circ}$, $67.5^{\circ}$ and $90^{\circ}$ with the bed joints were considered. The brick units and masonry system developed by Prof. S.N. Sinha were used in present investigation. Eighteen specimens of size $500mm{\times}100mm{\times}700mm$ and twenty seven specimens of size $500mm{\times}100mm{\times}500mm$ were tested. The envelope stress-strain curve, common point curve and stability point curve were established for all five cases of loading with respect to bed joints. A general analytical expression is proposed for these curves which fit reasonably well with the experimental data. Also, the stability point curve has been used to define the permissible stress level in the brick masonry.

• Journal of the Korean Mathematical Society
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• v.48 no.1
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• pp.159-167
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• 2011

We consider a curve $\alpha$= $\alpha$(s) in Minkowski 3-space $E_1^3$ and denote by {T, N, B} the Frenet frame of $\alpha$. We say that $\alpha$ is a slant helix if there exists a fixed direction U of $E_1^3$ such that the function is constant. In this work we give characterizations of slant helices in terms of the curvature and torsion of $\alpha$. Finally, we discuss the tangent and binormal indicatrices of slant curves, proving that they are helices in $E_1^3$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2353-2360
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• 2000

Statistical fatigue properties of metallic materials are increasingly required for reliability design purpose. In this study, static and fatigue tests were conducted and the normal, log-normal, two -parameter Weibull distributions at the 5% significance level are compared using the Kolmogorov-Smirnov goodness-of-fit test. Parameter estimation were compared with experimental results using the maximum likelihood method and least square method. It is found that two-parameter Weibull distribution and maximum likelihood method provide a good fit for static and fatigue life data. Therefore, it is applicable to the static and fatigue life analysis of the spheroidal graphite cast iron. The P-S-N curves were evaluated using log-normal distribution, which showed fatigue life behavior very well.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.83-83
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• 2009

The automotive chassis components are structural assemblies that support the engine, suspension, and steering components of the vehicle. For the development of AHSS components, the durability analysis is important. In this paper, the low cycle fatigue property of AHSS was evaluated for the geometry complex and local plasticity in the base material. The GMAW optimization was implemented for the weld soundness using the moving least square method. And the weld S-N curves of AHSS were evaluated to access durability analysis for the weld region. For the verification, the durability analysis of the couple torsion beam axle (CTBA) was performed and compared to the rig test result. The durability analysis using the low cycle fatigue property and the evaluated weld S-N curve of AHSS met the good agreement with the test result.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.12
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• pp.60-68
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• 1993

Thw VLSI device of submicron level trends to have a low level of reliability because of hot carriers which are caused by short channel effects and which do not appear in a long-channel MOSFET operated in 5V. In order to minimize the generation of hot carrier, much research has been made into various types of drain structures. This study has suggested CG MOSFET (Concaved Gate MOSFET) as new drain structure and compared its electrical characteristics with those of the conventional MOSFET and LDD-structured MOSFET by making use of a simulation method. These three device were assumed to be produced by the LOCOS process and a computer-based analysis(PISCES-2B simulator) was carried out to verify the hot electron-resistant behaviours of the devices. In the present simulation, the channel length of these devises was 1.0$\mu$m and their DC characteristics, such as VS1DT-IS1DT curves, gate and substrate current, potential contours, breakdown voltage and electric field were compared with one another.

• Journal of the Korean Chemical Society
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• v.18 no.1
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• pp.8-11
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• 1974

The solvolysis of p-substituted benzenesulfonyl chlorides $(substituents:p-H, p-Br, p-NO_2, p-OCH_3)$ in acetonitrile-water mixtures below 50 % of water content has been studied kinetically. Results show that Hammett plots give concaved curves but the mechanism is predominantly $S_N2$ and water acts both as nucleophile and general-base.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.679-682
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• 1995

The observed high-field magnetization curves of $Sm_{2}Fe_{17}N_{3.0}$ at 4.2 K and 296 K are well reproduced by the calculation using the Sm-Fe exchange field $2\mu\textrm{B}H_{ex}\;=\;320\;K$ and two crystalline electric field parameters ${A_{0}}^{2}=\;-910\;K$ and ${A_{1}}^{0}=\;200\;K$. The calculation shows that during the magnetization process along the hard axis at 4.2 K, the Sm moment rotates toward the direction antiparallel to H when H < 110 kOe and then returns to the field direction with further increase of the field. At 296 K, the Sm moment rotates toward the direction antiparallel to H monotonously with increasing field and finally becomes antiparallel to H when $H{\geq}H_{A}=210\;kOe$. The particular magnetization process of the Sm moment can be explained by the field-induced noncollinear coupling between the spin and orbital moments of the Sm ion.

• Steel and Composite Structures
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• v.39 no.3
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• pp.229-241
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• 2021

This work focused on aluminum foam sandwich (AFS) with different foam core densities and different face-sheet thicknesses subjected to constant amplitude three-point bending cyclic loading to study its fatigue performance. The experiments were conducted out by a high frequency fatigue test machine named GPS-100. The experimental results showed that the fatigue life of AFS decreased with the increasing loading level and the structure was sensitive to cyclic loading, especially when the loading level was under 20%. S-N curves of nine groups of AFS specimens were obtained and the fatigue life of AFS followed three-parameter lognormal distribution well. AFS under low cyclic loading showed pronounced cyclic hardening and the static strength after fatigue test increased. For the same loading level, effects of foam core density and face-sheet thickness on the fatigue life of AFS structure were trade-off and for the same loading value, the fatigue life of AFS increased with aluminum foam core density or face-sheet thickness monotonously. Core shear was the main failure mode in the present study.