• Journal of the Korean Mathematical Society
• /
• v.51 no.4
• /
• pp.721-734
• /
• 2014

Let M be a module over a commutative ring R, and let T(M) be its set of torsion elements. The total torsion element graph of M over R is the graph $T({\Gamma}(M))$ with vertices all elements of M, and two distinct vertices m and n are adjacent if and only if $m+n{\in}T(M)$. In this paper, we study the basic properties and possible structures of two (induced) subgraphs $Tor_0({\Gamma}(M))$ and $T_0({\Gamma}(M))$ of $T({\Gamma}(M))$, with vertices $T(M){\backslash}\{0\}$ and $M{\backslash}\{0\}$, respectively. The main purpose of this paper is to extend the definitions and some results given in [6] to a more general total torsion element graph case.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.813-817
• /
• 2002

This paper presents the reliability analysis technique on the dynamic characteristics of the torsion beam consisting the suspension system of passenger car. We utilize response surface method (RSM) and Monte Carlo simulation to obtain the response surface model that describes the limit state function for the natural frequencies of the torsion beam. Using the response surface model and the design optimization technique, we have obtained the optimized section considering the reliability of the torsion beam structure.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.14 no.1
• /
• pp.25-30
• /
• 2006

This study is about an optimum design to improve the kinematic and compliance characteristics of a torsion-beam suspension system. The kinematic and compliance characteristics of an initial design of the suspension was obtained through a roll-mode analysis. The objective function was set to minimize within design constraints. The coordinates of the connecting point between the torsion-beam and the trailing arm were treated as design parameters. Since the torsion-beam suspension has large nonlinear effects due to kinematic and elastic motion, Genetic Algorithms were employed for the optimal design. The optimized results were verified through a double-lane change simulation using the full vehicle model.

• Structural Engineering and Mechanics
• /
• v.59 no.3
• /
• pp.527-537
• /
• 2016

We describe a stress analysis of a single leaf flexure under torsion in which the warping effect is considered. The theoretical equations for the warping normal stress (${\sigma}_{xx}$) and shear stresses (${\tau}_{xz}$ and ${\tau}_{xy}$) are derived by applying the warping function of a rectangular cross-sectional beam and the twist angle equation that includes the warping torsion. The results are compared with those of the non-warping case and are verified using finite element analysis (FEA). A sensitivity analysis over the length, width, and thickness is performed and verified via FEA. The results show that the errors between the theory of warping stress results and the FEA results are lower than 4%. This indicates that the proposed theoretical stress analysis with warping is accurate in the torsion analysis of a single leaf flexure.

• Advances in pediatric surgery
• /
• v.9 no.1
• /
• pp.57-60
• /
• 2003

A 4 year old female with acute lower abdominal pain was admitted with the diagnosis of periappendiceal abscess made by ultrasonography. At laparotomy, the appendix was normal, but the left ovary was twisted and necrotic. Appendectomy and left salpingo-oophorectomy were performed. The pathology of the appendix was normal, and the left tube and ovary were ischemic and had hemorrhagic necrosis. Pediatric adnexal torsion may be difficult to diagnosis clinically. Sonography is the preferred imaging study. It usually confirms a pelvic mass but may not establish the diagnosis. The correct diagnosis of adnexal torsion is often made at exploration. The most common erroneous diagnosis is acute appendicitis or periappendiceal abscess. Therapy for adnexal torsion remains controversial. While extirpation has been the standard of treatment in the past, there are current proponents of conservative therapy with adnexal sparing. Early diagnosis may lead to more frequent salvage of affected adnexa.

• Structural Engineering and Mechanics
• /
• v.22 no.2
• /
• pp.241-262
• /
• 2006

NiTi-wire shape memory alloy (SMA) dampers, that utilize NiTi SMA wires to simultaneously damp tension, compression and torsion, was developed for structural control implementation in this study. First, eight reduced-scale NiTi-wire SMA dampers were constructed. Then tension, compression and torsion experiments using the eight reduced-scale NiTi-wire SMA dampers of different specification were done. The experimental results revealed all of the eight reduced-scale NiTi-wire SMA dampers had the ability to simultaneously supply tension-compression damping and torsion damping. Finally, mechanics analysis of the NiTi-wire SMA dampers was done based on a model of the SMA-wire restoring force and on tension-compression and torsion damping analysis. The damping analytical results were found to be similar to the damping experimental results.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1469-1471
• /
• 2003

The effect of heat treatment on torsion characteristics of high nitrogen steel wire has been studied by using torsion test, micro vickers hardness and scanning electron microscopy. After heat treatment at $600{\sim}700^{\circ}C$, torsion cycle was increased with increasing temperature. Especially, in case of high nitrogen steel wire heat treated at $650^{\circ}C$, torsion cycle was sharply increased. It is estimated that the cold-worked high nitrogen steel wire started to recrystallize around at $640^{\circ}C$ in air atmosphere.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.147-150
• /
• 2005

The torsion beam axle type is widely used in the rear suspension for small passenger car because of low cost, good performance and etc. The FE and dynamic analysis using the computer are very helpful for the efficiency of the torsion beam design. First of all, the reliability on the computational model must be verified for the analysis. In this study, The FE model of the torsion beam was verified according to comparison with he test data. And after making the flexible body using the FE model, the dynamic characteristic of the tubular type torsion beam axles was compared with that of the V-beam type.

• Coupled systems mechanics
• /
• v.12 no.1
• /
• pp.69-81
• /
• 2023

This paper considers a delamination analysis of a statically undetermined inhomogeneous beam structure of rectangular section with viscoelastic behavior under torsion. The beam is built in at its two ends. The beam has two longitudinal inhomogeneous layers with a delamination crack between them. A notch is made in the upper crack arm. The external torsion moment applied on the beam is a function of time. Under these conditions, the beam has one degree of indeterminacy. In order to derive the strain energy release rate, first, the static indeterminacy is resolved. Then the strain energy release rate is obtained by analyzing the balance of the energy with considering the viscoelastic behavior. The strain energy release rate is found also by analyzing the compliance of the beam for checkup. Solution of the strain energy release rate in a beam without a notch in the upper crack arm is derived too. In this case, the beam has two degrees of static indeterminacy (the torsion moment in the upper crack arm is treated as an additional internal redundant unknown). A parametric investigation of the strain energy release rate is carried-out.

• Journal of the Korean Mathematical Society
• /
• v.50 no.5
• /
• pp.1051-1066
• /
• 2013

By utilizing known characterizations of ${\omega}$-Noetherian rings in terms of injective modules, we give more characterizations of ${\omega}$-Noetherian rings. More precisely, we show that a commutative ring R is ${\omega}$-Noetherian if and only if the direct limit of GV -torsion-free injective R-modules is injective; if and only if every R-module has a GV -torsion-free injective (pre)cover; if and only if the direct sum of injective envelopes of ${\omega}$-simple R-modules is injective; if and only if the essential extension of the direct sum of GV -torsion-free injective R-modules is the direct sum of GV -torsion-free injective R-modules; if and only if every $\mathfrak{F}_{w,f}(R)$-injective ${\omega}$-module is injective; if and only if every GV-torsion-free R-module admits an $i$-decomposition.