• Communications of the Korean Mathematical Society
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• v.32 no.3
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• pp.653-659
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• 2017

Let $p{\geq}1$ be a real number. A tuple $T=(T_1,{\ldots},T_n)$ of commuting bounded linear operators on a Banach space X is called an ${\ell}^p$-spherical isometry if ${\sum_{i=1}^{n}}{\parallel}T_ix{\parallel}^p={\parallel}x{\parallel}^p$ for all $x{\in}X$. The tuple T is called a toral isometry if each Ti is an isometry. By a result of Ansari, Hedayatian, Khani-Robati and Moradi, for every $n{\geq}1$, there is a supercyclic ${\ell}^2$-spherical isometric n-tuple on ${\mathbb{C}}^n$ but there is no supercyclic ${\ell}^2$-spherical isometry on an infinite-dimensional Hilbert space. In this article, we investigate the supercyclicity of ${\ell}^p$-spherical isometries and toral isometries on Banach spaces. Also, we introduce the notion of semicommutative tuples and we show that the Banach spaces ${\ell}^p$ ($1{\leq}p$ < ${\infty}$) support supercyclic ${\ell}^p$-spherical isometric semi-commutative tuples. As a result, all separable infinite-dimensional complex Hilbert spaces support supercyclic spherical isometric semi-commutative tuples.

• Bulletin of the Korean Mathematical Society
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• v.60 no.6
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• pp.1555-1566
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• 2023

A Hilbert space operator A ∈ B(H) is a generalised n-projection, denoted A ∈ (G-n-P), if A^*n = A. (G-n-P)-operators A are normal operators with finitely countable spectra σ(A), subsets of the set $\{0\}\,{\cup}\,\{\sqrt[n+1]{1}\}.$ The Aluthge transform à of A ∈ B(H) may be (G - n - P) without A being (G - n - P). For doubly commuting operators A, B ∈ B(H) such that σ(AB) = σ(A)σ(B) and ${\parallel}A{\parallel}\,{\parallel}B{\parallel}\;{\leq}\;{\parallel}{\tilde{AB}}{\parallel},$ ${\tilde{AB}}\;{\in}\;(G\,-\,n\,-\,P)$ if and only if $A\;=\;{\parallel}{\tilde{A}}{\parallel}\,(A_{00}\,{\oplus}\,(A_0\,{\oplus}\,A_u))$ and $B\;=\;{\parallel}{\tilde{B}}{\parallel}\,(B_0\,{\oplus}\,B_u),$ where A₀₀ and B₀, and A₀ ⊕ A_u and B_u, doubly commute, A₀₀B₀ and A₀ are 2 nilpotent, A_u and B_u are unitaries, A^*n_u = A_u and B^*n_u = B_u. Furthermore, a necessary and sufficient condition for the operators αA, βB, αà and ${\beta}{\tilde{B}},\;{\alpha}\,=\,\frac{1}{{\parallel}{\tilde{A}}{\parallel}}$ and ${\beta}\,=\,\frac{1}{{\parallel}{\tilde{B}}{\parallel}},$ to be (G - n - P) is that A and B are spectrally normaloid at 0.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.10
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• pp.1287-1292
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• 2007

The purpose of this study was to compare knowledge on hypertension and blood parameters through blood pressure control of hypertensive patients commuting to a public health center. Hypertensive subjects were classified according to their blood pressures into a well-controlled group (SBP<140 mmHg and DBP<90 mmHg, n=44) and an uncontrolled group ($SBP\geq140mmHg\;or\;DBP\geq90mmHg$, n=41). All subjects were interviewed for clinical characteristics, effort for health maintenance and knowledge on hypertension and nutrition. Biochemical measurement of blood urea nitrogen, creatinine, triglyceride, total cholesterol, HDL-cholesterol and fasting blood glucose (FBG) were obtained from subjects. The knowledge about hypertension and effort for health maintenance were not significantly different between the groups. However, the nutrition knowledge score of the well-controlled group was significantly higher (p<0.05) than that of the uncontrolled group. On the test of nutrition knowledge, 97.7% of the well-controlled group answered correctly to the item, 'Medication is an easy way to control blood pressure'. This result was significantly higher (p<0.05) than that of the uncontrolled group of whom 82.9% answered correctly. Participants in both groups had only a little understanding about the importance of a balanced diet. Blood parameters were in the normal range and there was not a significant difference between the groups. However total cholesterol, triglyceride and fasting blood glucose levels of the uncontrolled group were higher than those of the well-controlled group. Therefore, education programs about the continuous control of hypertension through careful monitoring, medication, and exercise are required. The uncontrolled group was especially in need of strengthening education. Also more effective nutrition education programs about low salt, high fiber, low cholesterol, and balanced diets are required for hypertensive patients commuting to public health center.

• Korean Management Science Review
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• v.9 no.1
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• pp.3-15
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• 1992

In this paper, we study a manufacturing system of serial stages with general service times, in which the production of each stage and the coordination of stages are controlled by Kanban discipline. This Kanban discipline is modeled as a Discrete Event Dynamic System and a system of recursive equations is applied to study the dynamics of the system. The recursive relationship enables us to compare this Kanban discipline with the other blocking disciplines such as transfer blocking, service blocking, block-and-hold b, and block-and-hold K, and the Kanban is shown to be superior to the other disciplines in terms of makespan and throughput. As a special case, two stages Kanban system is modeled as $C_2/C_2/1/N$ queueing system, and a recursive algorithm is developed to calculate the system performance. In optimizing the system performance, the stochastic optimization approach of Robbins-Monro is employed via perturbation analysis, the way to estimate the stochastic partial derivative based on only one sample trajectory of the system, and the required commuting condition is verified. Then the stochastic convexity result is established to provide second-order optimality condition for this parametric optimization problem.

• Journal of the Korean Institute of Rural Architecture
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• v.14 no.3
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• pp.33-40
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• 2012

This study is to clarify the actual conditions of small elementary school facilities in depopulation areas. The aim of this thesis is to present the directions for Reorganization of small school facilities. Research area was kumi and uiseong, the number of students decreased rapidly. And small elementary school facilities were surveyed. The results are as the follows; 1)After consider living zone, commuting distance, opinions of residents, it is advisable that the small size school(the number of students under 60) will be combined stronghold school. 2)In the case of relocation, first of all, should consider the characteristic of living zone, exchanging training programs between elementary schools. 3)The closed school facilities will be used consistently as public facilities with priority consideration of environmental characteristic and users' demand.

• Journal of Digital Convergence
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• v.18 no.8
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• pp.21-27
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• 2020

This paper studies the impact of domestic and foreign economic activity on mobility among regions. The shortage of human resources and demand continues in Eastern Europeans. Especially Ukrainians, have entered the Polish labor market to make up for the scarce areas. As a result, Poland's supply and demand in Ukraine is disproportionate. Minimum wage increases are putting continued pressure on employers. Therefore, the regression equation in the form of job-seeker's economic activity ratio, y= AX²+B,(x=settlers) can be used to grasp the relationship between curves. According to the domestic and foreign workers who migrated, economic activities was rather than increasing the local population, the settlers of nearby large cities is more proportional. Empirical analysis has shown that the human resource hub has increased migration to large cities and industrial. The hub 'A'nation has been created for mobility in 4th wave re-industry, and the same re-industrialization (N₂) in other cities has attracted nearby human resources, but not settle. After all, the hub relationship between N₁ and N₂ is a mobile relationship. Due to wage inequality or a positive wellbeing chasm, workers are not settled plant area but a nearby city, or commuting between borders is easy to go into the hub central city. However, this proved on emerging from the relatively temporary settlers in the AI era.

• Journal of Family Resource Management and Policy Review
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• v.25 no.3
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• pp.103-120
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• 2021

Recently, the importance of the fathers role in the care of young children has been emphasized in Korea for the balance of childcare responsibilities between mothers and fathers. This study investigates the trends in paternal childcare in Korea over the last 15 years. Childcare is divided into primary and developmental care and fathers's Childcare time and participation rates are inverstigated for dual- and single-income households. Data are collected from the four waves of the five-yearly Statistics of Korea Life Time Surveys between 2004(t₁) and 2019(t₄) including the workday time diaries of fathers with preschool children(n₁=2,264, n₂=1,242, n₃=959, n₄=952). Three major results are identified. First, paternal childcare time and participation rates have increased with dual-income fathers spending 24 more minutes a day with their young child(ren) in 2019 than in 2004, which is nearly double. Second, in the analysis of fathers' childcare time use and participation rates comparing primary and developmental care, primary care is found to have increased more than developmental care, especially among dual income fathers: this further exhibits a reversed relation between primary and developmental care over time. Third, the determinants of paternal childcare time are fathers' age, market labor time, commuting time, gender equality consciousness, and education. In particular, market labor time was significant in all four waves, while gender equality consciousness is only significant for single-income fathers. Based on these results, a specific agenda is provided for family-friendly policies to improve the balance of childcare roles between fathers and mothers, especially encouraging increased(significant and sufficient) participation of fathers in primary care activities.