• Korean Institute of Interior Design Journal
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• no.39
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• pp.12-19
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• 2003

M.C Escher was not a mathematician or architect, but a visual graphic woodblock artist. He expresses space in various angles such as illusion and space not represented in reality, repetition, geometric pattern and change in space vision. However, as his works represent the impossible space which is virtually not exist in reality, they were examined numerically by scientists and mathematicians rather than by designers. Because his distinctive approach to view space, his works have been highly evaluated by scholars in various fields. Based on the previous research by mathematicians and scientists, this study will examine the sp- atial logic was represented visually in the works of M.C Escher and find out the possible and adoptable alternatives for new space design and provide the design application direction in the expression of interior space.

• Bulletin of the Korean Mathematical Society
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• v.41 no.4
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• pp.699-708
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• 2004

Niebergall and Ryan posed many open problems on real hypersurfaces in complex space forms. One of them is "Are there any Ricci-parallel real hypersurfaces in complex projective space $P_2C$ or complex hyperbolic space $H_2C$\ulcorner" The purpose of present paper is to prove the nonexistence of such hypersurfaces.

• Communications of the Korean Mathematical Society
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• v.12 no.2
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• pp.355-364
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• 1997

In a Finsler space, we introduce a special $(\alpha,\beta)$-metric L satisfying $L^2(\alpha,\beta) = c_1\alpha^2 + 2c_2\alpha\beta + c_3\beta^2$, which $c_i$ are constants. We investigate the Berwald connection in a Finsler space with this special $\alpha,\beta)$-metric.

• The Pure and Applied Mathematics
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• v.30 no.4
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• pp.407-416
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• 2023

In this paper, we introduce the concept of C^*-algebra-valued quasi b-metric space and prove some existence and uniqueness theorems. Furthermore, we prove the Hyers-Ulam stability results for fixed point problems via C^*-algebra-valued extended quasi b-metric space.

• Honam Mathematical Journal
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• v.46 no.2
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• pp.237-248
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• 2024

In this manuscript, the hypersurfaces of non-flat Riemannian 4-space forms are considered. A hypersurface of a 4-dimensional Riemannian space form defined by an isometric immersion 𝐱 : M³ → 𝕄⁴(c) is said to be biconservative if it satisfies the equation (∆²𝐱 )^⊤ = 0, where ∆ is the Laplace operator on M³ and ⊤ stands for the tangent component of vectors. We study an extended version of biconservativity condition on the hypersurfaces of the Riemannian standard 4-space forms. The C-biconservativity condition is obtained by substituting the Cheng-Yau operator C instead of ∆. We prove that C-biconservative hypersurfaces of Riemannian 4-space forms (with some additional conditions) have constant scalar curvature.

• Bulletin of the Korean Mathematical Society
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• v.50 no.1
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• pp.161-173
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• 2013

This paper is concerned with the space $\mathcal{K}_{w^*}(X^*,Y)$ of $weak^*$ to weak continuous compact operators from the dual space $X^*$ of a Banach space X to a Banach space Y. We show that if $X^*$ or $Y^*$ has the Radon-Nikod$\acute{y}$m property, $\mathcal{C}$ is a convex subset of $\mathcal{K}_{w^*}(X^*,Y)$ with $0{\in}\mathcal{C}$ and T is a bounded linear operator from $X^*$ into Y, then $T{\in}\bar{\mathcal{C}}^{{\tau}_{\mathcal{c}}}$ if and only if $T{\in}\bar{\{S{\in}\mathcal{C}:{\parallel}S{\parallel}{\leq}{\parallel}T{\parallel}\}}^{{\tau}_{\mathcal{c}}}$, where ${\tau}_{\mathcal{c}}$ is the topology of uniform convergence on each compact subset of X, moreover, if $T{\in}\mathcal{K}_{w^*}(X^*, Y)$, here $\mathcal{C}$ need not to contain 0, then $T{\in}\bar{\mathcal{C}}^{{\tau}_{\mathcal{c}}}$ if and only if $T{\in}\bar{\mathcal{C}}$ in the topology of the operator norm. Some properties of $\mathcal{K}_{w^*}(X^*,Y)$ are presented.

• KIEAE Journal
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• v.12 no.3
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• pp.53-60
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• 2012

This research is an illustrative research to verify the thermo environmental change created after introduction of indoor pond through abridged model test and simulation analysis. Especially, temperature and comfort level are analyzed by adjusting factors like size of water space, distance length, and location. Summary of the research is as follows. First, the most effective size of water space is 7% of the indoor size, from southern side. Temperature reduction effect is about $1.6^{\circ}C$(5.5%), and for the comfort level, it is found that pmv index increases 8%. Second, based on the simulation of distance length with the sphere, it is more effective as it is close to the surface. If distance length is more than 0.5m, there is no effect on reduction of temperature and comfort level of indoor environment. Lastly, for the analysis by location of the introduced water space, simulation is undertaken by dividing the water space (14% of the indoor size) with front, side, rear and center types. Temperature reduction effect is found to be : front type ($-1.53^{\circ}C$), side type ($-0.82^{\circ}C$), rear type ($-0.44^{\circ}C$), center type ($-0.28^{\circ}C$), respectively. The indoor environment change data by introduction of water space, found in this research, is at initial phase, but it is deemed to be a basic data to refer when planning actual water space.

• The Bulletin of The Korean Astronomical Society
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• v.30 no.1
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• pp.38.2-38.2
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• 2005

• Carbon letters
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• v.15 no.3
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• pp.180-186
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• 2014

This study highlights a novel method and mechanism for the rapid and effective milling of carbon fibers (CFs) in silicon carbide (SiC) powder, and also the dispersion of CFs in SiC powder. The composite powders were prepared by chopping and exfoliation of CFs, and ball milling of CFs and SiC powder in isopropyl alcohol. A wide range of CFs loading, from 10 to 50 vol%, was studied. The milling of CFs and SiC powder was checked by measuring the average particle size of the composite powders. The dispersivity of CFs in SiC powder was checked through scanning electron microscope. The results show that the usage of exfoliated CF tows resulted in a rapid and effective milling of CFs and SiC powder. The results further show an excellent dispersion of CFs in SiC powder for all CFs loading without any dispersing agent.

• The Korean Journal of Pain
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• v.12 no.1
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• pp.114-118
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• 1999

Backgrouds: Cervical epidural blocks were used as part of a comprehensive multimodal treatment program for patients with chronic pain in the head, neck and upper extremities. The depth of the epidural space beneth the skin surface varies at different levels of the spinal column in the same patient. It also varies from patient to patient at the same vertebral level. We studied the distance the skin to the cervical epidural space in adults patients at different intervertebral spaces. Methods: Date were gathered from 628 patients having cervical epidural block for relief of cervical and upper extrimity pain. All blocks were performed using hanging drop method after loss of resistance with saline at C5-6, C6-7, C7-T1 intervertebral space. Results: Mean distances for skin to cervical epidural space (DSES) were 5.42 cm, 5.06 cm, 4.68 cm in male, 5.00 cm, 4.61 cm, 4.10 cm in female at C7-T1, C6-7, C5-6 intervertebral space. DSES correlated with body weight, neck circumference and body mass index significantly. Conclusion: In the cervical spine, DSES varies from space to space. The longest DSES were noted at C7-T1 level in male, and the shortest DSES were at C5-6 in female. DSES has significant relationships with weight, neck circumference and body mass index.