• Kyungpook Mathematical Journal
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• v.57 no.1
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• pp.133-144
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• 2017

In this paper, we study ruled surfaces in 3-dimensional Euclidean and Minkowski space in terms of their Gauss map. We obtain classification theorems for these type of surfaces whose Gauss map G satisfying ${\Box}G=f(G+C)$ for a constant vector $C{\in}{\mathbb{E}}^3$ and a smooth function f, where ${\Box}$ denotes the Cheng-Yau operator.

• Kyungpook Mathematical Journal
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• v.59 no.3
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• pp.445-464
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• 2019

In this paper, we propose a new iterative algorithm generated by a finite family of accretive operators in a q-uniformly smooth Banach space. We prove the strong convergence of the proposed iterative algorithm. The results presented in this paper are interesting extensions and improvements of known results of Qin et al. [Fixed Point Theory Appl. 2014(2014): 166], Kim and Xu [Nonlinear Anal. 61(2005), 51-60] and Benavides et al. [Math. Nachr. 248(2003), 62-71].

• Journal of Medicine and Life Science
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• v.16 no.1
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• pp.27-30
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• 2019

We describe a case of a 48-year-old Korean woman who had a subepithelial mass incidentally discovered by endoscopic examination. Endoscopic mucosal resection revealed a well-circumscribed whitish solid mass within the submucosal space. Microscopically, the tumor was comprised of sparse spindle cells in the dense collagenous stroma with several calcifications and lymphoid aggregates. Immunohistochemical analysis showed that the tumor cells are negative for c-kit, smooth muscle actin, desmin, S-100 and CD34. Based on these findings, the tumor was diagnosed with calcifying fibrous tumor.

• Communications of the Korean Mathematical Society
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• v.38 no.1
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• pp.47-53
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• 2023

The Terracini t-locus of an embedded variety X ⊂ ℙ^r is the set of all cardinality t subsets of the smooth part of X at which a certain differential drops rank, i.e., the union of the associated double points is linearly dependent. We give an easy to check criterion to exclude some sets from the Terracini loci. This criterion applies to tensors and partially symmetric tensors. We discuss the non-existence of codimension 1 Terracini t-loci when t is the generic X-rank.

• Journal of the Chungcheong Mathematical Society
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• v.23 no.4
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• pp.801-812
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• 2010

In this paper, we consider the convergence of the shrinking projection method for quasi-$\phi$-nonexpansive mappings. Strong convergence theorems are established in a uniformly smooth and strictly convex Banach space which enjoys the Kadec-Klee property.

• Journal of the Korean Mathematical Society
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• v.61 no.3
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• pp.515-545
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• 2024

Consider a Noetherian domain R₀ with quotient field K₀. Let K be a finitely generated regular transcendental field extension of K₀. We construct a Noetherian domain R with Quot(R) = K that contains R₀ and embed Spec(R₀) into Spec(R). Then, we prove that key properties of abelian varieties and smooth geometrically integral projective curves over K are preserved under reduction modulo p for "almost all" p ∈ Spec(R₀).

• Bulletin of the Korean Mathematical Society
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• v.61 no.2
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• pp.519-527
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• 2024

For a finite subgroup G of GL_n(ℂ), the moduli space 𝓜_𝜃 of 𝜃-stable G-constellations is rarely smooth. This note shows that for a group G of type ${\frac{1}{r}}(1,a,b)$ with r = abc + a + b, there is a generic stability parameter 𝜃 ∈ Θ such that the birational component Y_𝜃 of 𝜃-stable G-constellations provides a resolution of the quotient singularity X := ℂ³/G.

• Journal of the Korean Institute of Educational Facilities
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• v.19 no.2
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• pp.33-40
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• 2012

The number of foreign residents is expected to increase with the increase of international marriage in rural area and the avoidance of 3D jobs, which is also anticipated to cause various problems more serious. This kind of phenomenon will bring about the increase of the students from the multi-cultural families and a big change in the schools along with the decrease of the students in rural area. Currently, school's interest in and support for those students from multi-cultural families are focused on the promotion of their learning capability. However, I think that not just the support for the students from multi-cultural families but a new space for the two student-groups' smooth communication in schools is to be arranged. Accordingly, this study suggests. The support limited to educational programs for those students from multi-cultural families should be expanded to the school facilities. What kind of preparation should be done by school facilities in the future. There should be five steps of intermediate space with the additional function other than that of communication between Korean native students and those from multi-cultural families along with the utilization of existing rooms and space.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.278-294
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• 2015

Considering the guidance and control problem of the near space interceptor (NSI) during the terminal course, this paper proposes a three-channel independent integrated guidance and control (IGC) scheme based on the backstepping sliding mode and finite time disturbance observer (FTDO). Initially, the three-channel independent IGC model is constructed based on the interceptor-target relative motion and nonlinear dynamic model of the interceptor, in which the channel coupling term and external disturbance are regarded as the total disturbances of the corresponding channel. Then, the FTDO is introduced to estimate the target acceleration and control system loop disturbances, and the feed-forward compensation term based on the estimated values is employed to effectively remove the effect of disturbances in finite time. Subsequently, the IGC algorithm based on the backstepping sliding mode is also given to obtain the virtual control moment. Furthermore, a robust least-squares weighted control allocation (RLSWCA) algorithm is employed to distribute the previous virtual control moment among the corresponding aerodynamic fins and reaction jets, which also takes into account the uncertainty in the control effectiveness matrix. Finally, simulation results show that the proposed IGC method can obtain the small miss distance and smooth interceptor trajectories.

• The Journal of Sustainable Design and Educational Environment Research
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• v.10 no.2
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• pp.61-72
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• 2011

The purpose of this study is to carry out the research of the satisfaction level of consumers (students and teachers) and managerial characteristics for model classes of the subject classroom system and to draw the effective plan of the system. The conclusions are as follows First, the biggest advantage of the system is to fulfill the educational goal according to an individual level and ability of each student while the biggest disadvantage is the inconvenience of students to change their classrooms for each specific class. Second, it is necessary to rearrange the classrooms according to the applied subjects from the aspect of curriculum management since the time frame is not convenient for recess. English and mathematics are required preferentially as applied subjects, however Korean (as a national language) and science are needed to be taught with level-differentiated classes, too. The ideal size of classes is most likely 20-25 students according to the result of research. Lastly, the space of environment is another requirement to secure smooth flow of students' movements and extra space for technical devices used for information research. The above analysis indicates the necessity of supplementation in space planning for further implementation of subject classroom system in secondary school.