• Journal of the Chungcheong Mathematical Society
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• v.22 no.4
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• pp.777-787
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• 2009

In this paper we investigate the upper bound on the Castelnuovo-Mumford regularity of a graded module with linear free presentation. Let M be a finitely generated graded module over a polynomial ring R with zero dimensional support. We prove that if M is generated by elements of degree $d{\geq}0$ with a linear free presentation $$\bigoplus^p{R}(-d-1)\longrightarrow^{\phi}\bigoplus^q{R}(-d){\longrightarrow}M{\longrightarrow}0$$, then the Castelnuovo-Mumford regularity of M is at most d+q-1. As an important application, we can prove vector bundle technique, which was used in [11], [13], [17] as a tool for obtaining several remarkable results.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.556-561
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• 1988

Shrink-rings (Stress-rings) are used in the fabrication of dies for cold forming and powder compaction processes to increase the allowable pressures for a given die material. Optimum procedures are to minimize a die thickness under the conditions that the stress distributions in the die and stress-rings utilize fully the strength available in each of the die elements. This paper proposes a new approach, where the maximum allowable shrinking pressures are calculated on shrinkage plans in the radial direction and the fractional shrinking pressures below the maximum allowable pressures are used as the design values. Two criteria for the optimal die design are used: Maximum shear stress limit for one-piece dies and zero tensile stress limit for combined dies. A computer program, DIECOM, is developed for illustrating the computer-aided design procedures. Finally, examples for each case are presented in this paper.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.274-279
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• 2000

This paper is concerned with the orthotropic problem of diaphragm-type air springs which consist of rubber linings, nylon reinforced rubber composite and bead ring. The analysis is carried out with a finite element method developed to consider the orthotropic properties, geometric nonlinearity using four-node degenerated shell element with reduced integration. Physical stabilization scheme is used to control the zero-energy modes of the element. An inflation analysis and a lateral deformation analysis of an air spring are carried out. Numerical analysis results demonstrate the variation of the outer diameter, the fold height, the vertical force and the lateral force.

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

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.5
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• pp.622-635
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• 2009

Laser Inertial Navigation System(LINS) consists of Ring Laser Gyroscopes(RLG) and accelerometers. RLG has a lock-in region in which there is zero output for input angular rates less than about 0.1deg/sec. The lock-in region is generated by the imperfect mirrors in RLG. To avoid the lock-in region, a sinusoidal motion called dither motion is applied on RLG. Therefore this dither motion is measured by RLG/accelerometer even if at a stop state. In this situation, the performance on the initial alignment of LINS can be degraded. In this paper, we analyze the performance on the initial alignment of LINS theoretically and experimentally. Analysis results include how dither motion, the pre-filter and the corner frequency in alignment loop affects the performance on the initial alignment of LINS.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.9-12
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• 2005

In this study, to investigate shrinkage and cracking behavior of 120MPa UHSC, free and restrained drying shrinkage test were performed. Three strength levels(50MPa, 80MPa, 120MPa) were used and the effect of mineral admixtures(fly ash, slag) on free and restrained shrinkage was investigated. From comparing the result of pin -penetration test with the result of ring test, Time-Zero was determined as initial set. Shrinkage test results show that autogenous shrinkage of UHSC was much higher than that of HSC, VHSC and fly ash delayed cracking age in UHSC by decreasing autogenous shrinkage. Additional free concrete rings(with restraint removed) were also tested to check the influence of the geometry of the specimens on free shrinkage. And then the relationship between free shrinkage and restrained shrinkage was investigated.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.2
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• pp.149-155
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• 2001

The use of primitive cell volume and zero order Laue (ZOLZ) pattern is proposed to identify phase in a complex microstructure. Single convergent beam electron pattern containing higher order Laue zone ring from a nanosized region is sufficient to calculate the primitive cell volume of the phase, while ZOLZ pattern is used to determine the zone axis of the crystal. A computer program is used to screen out possible phases from the value of measured cell volume from convergent beam electron diffraction (CBED) pattern. Indexing of ZOLZ pattern follows in the program to find the zone axis of the identification from a single CBED pattern. An example of the analysis is given from the rapidly solidified $Al-Al_3Ti$ system.

• Communications of the Korean Mathematical Society
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• v.31 no.4
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• pp.695-701
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• 2016

Let I and J be two ideals of a commutative Noetherian ring R and M, N be two non-zero finitely generated R-modules. Let t be a non-negative integer such that $H^i_{I,J}(N)$ is (I, J)-minimax for all i < t. It is shown that the generalized local cohomology module $H^i_{I,J}(M,N)$ is (I, J)-Cofinite minimax for all i < t. Also, we prove that the R-module $Ext^j_R(R/I,H^i_{I,J}(N))$ is finitely generated for all $i{\leq}t$ and j = 0, 1.

• Bulletin of the Korean Mathematical Society
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• v.56 no.2
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• pp.471-477
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• 2019

Let (R, m) be a commutative Noetherian ring, I an ideal of R and M a non-zero finitely generated R-module. We show that if M and $H_0(I,M)$ are aCM R-modules and $I=(x_1,{\cdots},x_{n+1})$ such that $x_1,{\cdots},x_n$ is an M-regular sequence, then $H_i(I,M)$ is an aCM R-module for all i. Moreover, we prove that if R and $H_i(I,R)$ are aCM for all i, then R/(0 : I) is aCM. In addition, we prove that if R is aCM and $x_1,{\cdots},x_n$ is an aCM d-sequence, then depth $H_i(x_1,{\cdots},x_n;R){\geq}i-1$ for all i.

• Bulletin of the Korean Mathematical Society
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• v.59 no.6
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• pp.1387-1408
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• 2022

Let R be a commutative ring with a non-zero identity, S be a multiplicatively closed subset of R and M be a unital R-module. In this paper, we define a submodule N of M with (N :_R M)∩S = ∅ to be weakly S-prime if there exists s ∈ S such that whenever a ∈ R and m ∈ M with 0 ≠ am ∈ N, then either sa ∈ (N :_R M) or sm ∈ N. Many properties, examples and characterizations of weakly S-prime submodules are introduced, especially in multiplication modules. Moreover, we investigate the behavior of this structure under module homomorphisms, localizations, quotient modules, cartesian product and idealizations. Finally, we define two kinds of submodules of the amalgamation module along an ideal and investigate conditions under which they are weakly S-prime.