• Bulletin of the Korean Mathematical Society
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• v.23 no.2
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• pp.123-132
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• 1986

Let X be a real Banach space with norm vertical bar . vertical bar and let I denote the identity operator. Then an operator A.contnd.X*X with domain D(A) and range R(A) is said to be accretive if vertical bar x$_{1}$-x$_{2}$ vertical bar.leq.vertical bar x$_{1}$-x$_{2}$+r(y$_{1}$-y$_{2}$) vertical bar for all y$_{i}$.mem.Ax$_{i}$, i=1, 2, and r>0. An accretive operator A.contnd.X*X is m-accretive if R(I+rA)=X for all r>0.r>0.

• Kyungpook Mathematical Journal
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• v.57 no.4
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• pp.667-676
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• 2017

We study the positive $C^1$ function z = f(x, y) defined on the plane ${\mathbb{R}}^2$. For a rectangular domain $[a,b]{\times}[c,d]{\subset}{\mathbb{R}}^2$, we consider the volume V and the surface area S of the graph of z = f(x, y) over the domain. We also denote by (${\bar{x}}_V,\;{\bar{y}}_V,\;{\bar{z}}_V$) and (${\bar{x}}_S,\;{\bar{y}}_S,\;{\bar{z}}_S$) the geometric centroid of the volume under the graph of z = f(x, y) and the centroid of the graph itself defined on the rectangular domain, respectively. In this paper, first we show that among nonconstant $C^2$ functions with isolated singularities, S = kV, $k{\in}{\mathbb{R}}$ characterizes the family of catenary rotation surfaces f(x, y) = k cosh(r/k), $r={\mid}(x,y){\mid}$. Next, we show that one of $({\bar{x}}_S,\;{\bar{y}}_S)=({\bar{x}}_V,\;{\bar{y}}_V)$, $({\bar{x}}_S,\;{\bar{z}}_S)=({\bar{x}}_V,\;2{\bar{z}}_V)$ and $({\bar{y}}_S,\;{\bar{z}}_S)=({\bar{y}}_V,\;2{\bar{z}}_V)$ characterizes the family of catenary rotation surfaces among nonconstant $C^2$ functions with isolated singularities.

• East Asian mathematical journal
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• v.38 no.1
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• pp.1-12
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• 2022

Let R be a ring with an endomorphism σ and a σ-derivation δ. R is called (σ, δ)-Baer (resp. (σ, δ)-quasi-Baer, (σ, δ)-p.q.-Baer, (σ, δ)-p.p.) if the right annihilator of every right (σ, δ)-set (resp., (σ, δ)-ideal, principal (σ, δ)-ideal, (σ, δ)-element) of R is generated by an idempotent of R. In this paper, for a given Ore extension A = R[x; σ, δ] of R, the following properties are investigated: If R is a σ-rigid ring in which σ and δ commute, then (1) R is (σ, δ)-Baer if and only if R is (σ, δ)-quasi-Baer if and only if A is (${\bar{\sigma}},\;{\bar{\delta}}$)-Baer if and only if A is (${\bar{\sigma}},\;{\bar{\delta}}$)-quasi-Baer; (2) R is (σ, δ)-p.p. if and only if R is (σ, δ)-p.q.-Baer if and only if A is (${\bar{\sigma}},\;{\bar{\delta}}$)-p.p. if and only if A is (${\bar{\sigma}},\;{\bar{\delta}}$)-p.q.-Baer.

• Communications of the Korean Mathematical Society
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• v.10 no.2
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• pp.349-355
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• 1995

Let $D \subset C^n$ be a smoothly bounded pseudoconvex domain and let ${\bar{D}_r}_r$ be a family of smooth perturbations of $\bar{D}$ such that $\bar{D} \subset \bar{D}_r$. Let $K_D(z, w)$ be the Bergman kernel function on $D \times D$. Then $lim_{r \to 0} K_{D_r}(z, w) = K_D(z, w)$ locally uniformally on $D \times D$.

• Communications of the Korean Mathematical Society
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• v.35 no.4
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• pp.1045-1056
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• 2020

Let R be a commutative ring with unity. The extension of annihilating-ideal graph of R, $^{\bar{\mathbb{AG}}}$(R), is the graph whose vertices are nonzero annihilating ideals of R and two distinct vertices I and J are adjacent if and only if there exist n, m ∈ ℕ such that IⁿJ^m = (0) with Iⁿ, J^m ≠ (0). First, we differentiate when 𝔸𝔾(R) and $^{\bar{\mathbb{AG}}}$(R) coincide. Then, we have characterized the diameter and the girth of $^{\bar{\mathbb{AG}}}$(R) when R is a finite direct products of rings. Moreover, we show that $^{\bar{\mathbb{AG}}}$(R) contains a cycle, if $^{\bar{\mathbb{AG}}}$(R) ≠ 𝔸𝔾(R).

• Journal of the Korean Mathematical Society
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• v.47 no.3
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• pp.455-466
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• 2010

For an endomorphism $\alpha$ of a ring R, we introduce the weak $\alpha$-skew Armendariz rings which are a generalization of the $\alpha$-skew Armendariz rings and the weak Armendariz rings, and investigate their properties. Moreover, we prove that a ring R is weak $\alpha$-skew Armendariz if and only if for any n, the $n\;{\times}\;n$ upper triangular matrix ring $T_n(R)$ is weak $\bar{\alpha}$-skew Armendariz, where $\bar{\alpha}\;:\;T_n(R)\;{\rightarrow}\;T_n(R)$ is an extension of $\alpha$ If R is reversible and $\alpha$ satisfies the condition that ab = 0 implies $a{\alpha}(b)=0$ for any a, b $\in$ R, then the ring R[x]/($x^n$) is weak $\bar{\alpha}$-skew Armendariz, where ($x^n$) is an ideal generated by $x^n$, n is a positive integer and $\bar{\alpha}\;:\;R[x]/(x^n)\;{\rightarrow}\;R[x]/(x^n)$ is an extension of $\alpha$. If $\alpha$ also satisfies the condition that ${\alpha}^t\;=\;1$ for some positive integer t, the ring R[x] (resp, R[x; $\alpha$) is weak $\bar{\alpha}$-skew (resp, weak) Armendariz, where $\bar{\alpha}\;:\;R[x]\;{\rightarrow}\;R[x]$ is an extension of $\alpha$.

• International Journal of Human Ecology
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• v.14 no.2
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• pp.93-103
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• 2013

This study investigated the relationship of clothing microclimate and physiological responses in order to examine the layering effects on the clothing microclimate as an index to predict clothing thermal insulation ($I_{cl}$). Experiments were conducted in a $15^{\circ}C$ environment on six physically active males. Increased clothing layers resulted in higher mean temperature inside the clothing ($\bar{T}_{cl}$) and $I_{cl}$. The $I_{cl}$ had a high correlation with: $\bar{T}_{cl}$ (r = 0.556), the difference between the innermost surface temperature and the outermost surface temperature at the chest (DST) (r = 0.549) and the temperature inside clothing at the abdomen (r = 0.478). $\bar{T}_{cl}$ had the highest correlation with the temperature inside clothing at the abdomen (r = 0.889). $\bar{T}_{cl}$ also had the highest correlation with $\bar{T}_{sk}$ (r = 0.860). The results showed that the relationship between $I_{cl}$ and $\bar{T}_{cl}$ was linear (p < .01). Thermal comfort had a negative correlation with $\bar{T}_{cl-thigh}$ (r=-0.411) and $\bar{T}_{cl}$ (r = -0.323) (p < .01.)

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.409-412
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• 2011

Maximum speed of the train could not exceed over 160km/h with R-bar system in the underground type tunnel structure. By the research to overcome this speed limit, maximum speed has reached up to 200~250km/h recently by new R-bar system. It is under discussion to construct Metro Express Line between Gyonggido and Seoul which requires maximum speed 180km/h~230km/h. New R-bar is an optimal system to achieve the speed improvement in this line. This study shows application of the high speed R-bar system in the underground tunnel section.

• Journal of Korean Medicine Rehabilitation
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• v.24 no.3
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• pp.29-37
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• 2014

Objectives Osteoporosis is an impending problem in the rapidly aging society. The purpose of this study is to identify the effects of Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) on osteoporosis induced by ovariectomy in rats. Methods 24 rats were randomly assigned to a SHAM group, a control group, and a Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group (n=8). Ovaries were extracted and for 8 weeks, the rats were given dry feeds and Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group were given a mixture of dry feeds and Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$). At 8 weeks, their body weight, femur mass, tibia ash per body ratio, overall surface area and thickness of the trabeculae, overall surface area of the osteoblasts, and the number of osteoclasts were measured and levels of albumin, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), total-cholesterol, calcium and estradiol were recorded. Results There was no significant difference in the weight of the femur and the tibia ash per body ratio. The Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group had significantly thicker trabeculae than the control group and showed a minimal increase of overall surface area of the trabeculae. The overall surface area of the osteoblasts and the number of osteoclasts decreased in the Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group. There were no statistically significant differences in AST, ALT, ALP, total cholesterol, phosphorus, and estradiol levels. On the contrary the Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) group had significantly higher levels of Albumin, triglyceride, and calcium. Conclusions It can be concluded that oral intake of Yoohyangheukho-dan ($R{\check{u}}xi{\bar{a}}ngh{\bar{e}}ih{\check{u}}-d{\bar{a}}n$) prevents the thinning process of the trabeculae. Thus, it may have positive effects on the treatment and prevention of osteoporosis in postmenopausal women.

• Journal of Life Science
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• v.14 no.2
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• pp.368-373
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• 2004

We have obtained fertile transgenic rice plants resistant to the broad spectrum herbicide Bast $a^{(R)}$ (active ingredient phosphinothricin, PPT) by PEG-mediated transformation procedure. The plasmid pCaMV35S::Bar was used to deliver the bar gene into embryogenic suspension culture-derived protoplasts of rice (Oryza sativa L.). Transformed plants were regenerated and selected on medium containing 15 mg/l of phosphinothricin. Stable integration and expression of the bar gene in transgenic rice plants was confirmed by Southern and Northern blot analysis. Transgenic $R_1$ plants were also confirmed by assays for phosphinothricin acetyltransferase (PAT) activity. The bar gene was expressed in the primary transgenic rice plants and in the next generation progeny, in which it showed a 3 : 1 Mendelian inheritance pattern. Transgenic $R_1$ and $R_2$ plants were resistant to the herbicide Bast $a^{(R)}$ when sprayed at rates used in field practice.ice.