• Korean Journal of Mathematics
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• 제22권1호
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• pp.151-167
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• 2014

Let M, N be modules over a ring R and $[M,N]=Hom_R(M,N)$. The concern is study of: (1) Some fundamental properties of [M, N] when [M, N] is regular or semipotent. (2) The substructures of [M, N] such as radical, the singular and co-singular ideals, the total and others has raised new questions for research in this area. New results obtained include necessary and sufficient conditions for [M, N] to be regular or semipotent. New substructures of [M, N] are studied and its relationship with the Tot of [M, N]. In this paper we show that, the endomorphism ring of a module M is regular if and only if the module M is semi-injective (projective) and the kernel (image) of every endomorphism is a direct summand.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.526-544
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• 2021

Based on the potential flow theory, a fully nonlinear numerical procedure is developed with boundary element method to analyze the interaction between a fixed semi-submersible platform and incident waves in open water. The incident wave is separated from the scattered wave under fully nonlinear boundary conditions. The mixed Euler-Lagrangian method is used to capture the position of the disturbed wave surface in local coordinate systems. The wave forces exerted on an inverted conical frustum are used to ensure the accuracy of the present method and good agreements with published results are obtained. The hydrodynamic characteristics of the semi-submersible platform interacting with regular waves are analyzed. Pressure distribution with time and space, tension and compression of the platform under wave action are investigated. 3D behaviors of wave run-ups are predicted. Strong nonlinear phenomena such as wave upwelling and wave interference are observed and analyzed.

• 대한토목학회논문집
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• 제29권2A호
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• pp.131-143
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• 2009

지진하중과 같은 횡하중에 대하여 교량구조물의 아칭작용은 교대 사이의 상부구조에 의해 발생하며 이를 상부구조의 저항능력이라고도 한다. 교량구조물의 아칭작용의 크기는 경간의 수에 영향을 받으며 또한 상부구조, 교대와 교각의 연결조건 및 상부구조와 하부구조의 강성비에도 영향을 받는다. 프리캐스트 콘크리트 상자형 교량의 비탄성 지진응답에 대한 아칭작용의 영향을 분석하기 위하여 경간수에 따른 두 가지 종류의 예제교량(교량 SB와 교량 LB), 교각의 높이의 배열에 따른 세가지 종류(대칭, 비대칭)의 교량, 상부구조와 하부구조의 연결조건에 따른 세가지 교량(형식 A, B, C)등에 대한 구분을 조합하여 18가지 종류의 예제구조물을 작성하였으며, 이 예제구조물들에 대하여 역량스펙트럼해석, 비탄성 시간이력해석을 수행하여 지진응답을 비교하여 아칭작용의 영향을 분석하였다. 아칭작용의 영향(최대변위의 감소와 저항능력의 증가)은 교량 SB(short bridge)의 경우가 교량 LB(long bridge) 보다 크게 나타났으며 대칭교량의 경우가 비대칭교량에 비하여 크게 나타남을 알수 있었다.

• 충청수학회지
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• 제9권1호
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• pp.123-128
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• 1996

This paper is to study the regular $^*$ semigroup, to define the self-involutive semi-group, to introduce the properties of the self-involutive semigroup, and to generalize the maximum idempotent-separating congruence which was found by conditioning self-involutive semigroups.

• Kyungpook Mathematical Journal
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• 제32권1호
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• pp.21-30
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• 1992

• 한국정밀공학회지
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• 제17권6호
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• pp.143-152
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• 2000

The comer filling in shaped drawing process is an important characteristic, unlike the round drawing. It has also influence on the dimensional accuracy of the product. In this study, therefore, the shaped drawing process has been simulated by the three dimensional rigid-plastic finite element method in order to investigate the effect of process variables such as reduction in area and semi-die angle to the corner filling. The artificial neural network has also been introduced to reduce the number of simulations. To verify the results of simulations, experiments have been performed on the real industrial products. According to the results, the main process variable on the corner filling is the combination of semi-die angle in the irregular shaped drawing processes, but in the case of regular shaped drawing processes, reduction in area has great influence on the corner filling.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.81-90
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• 2004

A zonal embedded grid technique has been developed for computation of the two-dimensional Navier-Stokes equations with cylindrical coordinates. The fundamental idea of the zonal embedded grid technique is that the number of azimuthal grids can be made small near the origin of the coordinates so that the grid size is more uniformly distributed over the domain than with the conventional regular-grid system. The code developed using this technique combined with the explicit, finite-volume method was then applied to calculation of the spin-up flows within a semi-circular cylinder. It was shown that the numerical results were in good agreement with the experimental results both qualitatively and quantitatively.

• 천문학회보
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• 제40권2호
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• pp.58.4-59
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• 2015

We have performed single dish and VLBI monitoring observations of $H_2O$ and SiO masers toward the semi-regular variable star R Crateris using the Korean VLBI Network(KVN) 4 band receiving system. In the case of VLBI observations at 3 epochs, successful superposed maps of $H_2O$ and SiO masers were obtained on 2015 May by adopting the Source Frequency Phase Referencing(SFPR) method. These results enable us to investigate the development of outflow and asymmetric motions from SiO maser to $H_2O$ maser regions according to stellar pulsation which are closely related with a mass-loss process. Single dish monitoring observations were carried out from 2009 June to 2015 May. Intensity variations between $H_2O$ and SiO masers were investigated according to stellar phases together with peak velocity variations. We will compare the VLBI results with those of single dish.

• 천문학회보
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• 제41권1호
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• pp.43.1-43.1
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• 2016

With the Korean VLBI Network (KVN), both single dish and VLBI monitoring observations of H2O and SiO masers were performed toward the semi-regular variable star R Crateris. In the case of 11 VLBI monitoring observations from Jan. 5, 2014 to Jan. 7, 2016, successful superposed maps of H2O and SiO masers were obtained at 7 epochs by adopting the Source Frequency Phase Referencing (SFPR) method. These results enable us to investigate the development of outflow and asymmetric motions from SiO maser to H2O maser regions according to stellar pulsation which are closely related with a mass-loss process. Single dish monitoring observations of H2O and SiO masers were also carried out from 2009 June to 2016 Feb. Intensity variations between H2O and SiO masers were investigated according to stellar optical phases together with peak velocity variations with respect to the stellar velocity. We will compare the VLBI results among different maser transitions with those of single dish.

• Journal of applied mathematics & informatics
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• 제41권5호
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• pp.1037-1046
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• 2023

The reason behind to investigate axiom systems with fewer axioms into investigate what types of results still hold, and what results become more general. Seminearrings obtained by the generalisation of nearrings and semirings. Clearly, seminearrings are common abstraction of semirings and nearrings. The aim of this work is to carry out an extensive study on algebraic structure of seminearrings and the major objective is to further enhance the theory of seminearrings in order to study the special structures of seminearrings, this work addresses some special structures of seminearrings such as right duo seminearrings. The right ideal of a seminearring need not be a left ideal. We focused on those seminear-rings which demonstrate this property. A seminearring S is right duo if every right ideal is two sided. Here we have concentrated on the seminearring which are right duo and regular. Main aim of this paper is to deal with properties of regularity in right duo seminearring. We have given some results on right duo seminearring. Followed by that, we have derived some theorems on the relation between the properties of seminearring such as regularity, semi simplicity and intra-regularity in right duo seminearring. We also illustrate this concept with suitable examples.