• 대한수학회논문집
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• 제31권3호
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• pp.585-590
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• 2016

Suppose $T_{\varphi}$ is a 2-hyponormal Toeplitz operator whose self-commutator has rank $n{\geq}1$. If $H_{\bar{\varphi}}(ker[T^*_{\varphi},T_{\varphi}])$ contains a vector $e_n$ in a canonical orthonormal basis $\{e_k\}_{k{\in}Z_+}$ of $H^2({\mathbb{T}})$, then ${\varphi}$ should be an analytic function of the form ${\varphi}=qh$, where q is a finite Blaschke product of degree at most n and h is an outer function.

• 대한수학회보
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• 제47권1호
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• pp.179-186
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• 2010

This paper concerns the propagation phenomenon of weighted shifts. We here establish the existence of positive real numbers b and c (1 < b < c) such that the recursive weighted shift $W_{1,(1,\sqrt{b}\sqrt{c})$^ is quadratically but not cubically hyponormal.

• Kyungpook Mathematical Journal
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• 제49권4호
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• pp.683-689
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• 2009

We investigate the gaps among classes of weakly hyponormal composition operators induced by Embry characterization for the subnormality. The relationship between subnormality and weak hyponormality will be discussed in a version of composition operator induced by a non-singular measurable transformation.

• Journal of applied mathematics & informatics
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• 제39권3_4호
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• pp.443-454
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• 2021

In this paper, we discuss the backward extensions of Bergman shifts W_α(m), where $${\alpha}(m)\;:\;\sqrt{\frac{m}{m+1}},\;{\sqrt{\frac{m+1}{m+2}}},\;{\cdots},\;(m{\in}\mathbb{N})$$. We obtained a complete description of the n-hynonormality for backward one, two and three step extensions.

• 한국학교보건학회지
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• 제1권1호
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• pp.103-113
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• 1988

The analysis of the visual impairment and refractive errors among 4,004 school children in Seoul in 1986 with ancilliary questionnaire on various socio-environmental and visual factors was conducted. The number of the student with subnormal vision (0.7 or less) was 1,552 (38,8 %), and the rate of subnormal vision was increased with the higher grading of the school classes. Rate of myopes among the 1,552 students vision 0.7 or less consists of 52 % in primary school, 83.5 % in middle school, and 94 % in high school, and they were increased with the higher grading of the school class. The acutest increase of rates were observed at the stages of 2nd year class of male, and 1st year class of female at the middle school. Among the glasses-wearer of myopic students of vision 0.5 or less, the rate of adequately corrected cases was 42.5 %, whereas the overcorrected in 6.8 %, and undercorrected in 49.3 %. The main reasons of glasses negligence among the non-possessor of glasses with the vision of 0.5 or less were indicated in prominence of numbers of' "no complaints without glasses" (42 %). "unawareness of visual disturbance" (20%), "annoyance with wearing glasses" (13.4%), and "no permission from parents" (11.5 %) rather than the "economical reasons". The amblyopic components were estimated 126 cases (3.2%) in combination of refractive errors. According to the analysis of ancilliary questionnaire, the-conclusion with the statistical significance was that the myopization of the children's eyes appeared susceptible with a number of socio-environmental factors including the eating habits, length of T.V. watching period and distance, reading distance and type of illumination during near work, and school achievement. The possibility of prevention in some extents of progress of the myopia following the improvement of the relevant environmental factors in younger stage of children would be considered as deducible one.

• 보건교육건강증진학회지
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• 제11권2호
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• pp.68-86
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• 1994

In order to provide data of effective health education for practice of preventive health behavior for visual acuity care. The authors investgated the actual acuity and health behavior for visual acuity care. The subjects of this study were 2250 students in high school. The data were collected by questionnaire developed for the purpose of this study which has been made through references and student's health record. The results were as follows, 1) As students move up to grade, the number of students with decreased visual acuity had a tendency to increase. In cases with decreased visual acuity below 0.2 in one or both eye, the number of cases was increased in accordance with moving up to grade, especially visual acuity of right eye was more decreased than that of left eye. 2) As to proportion of the group with decreased visual acuity among the total students, among 2250 students, students with decreased visual acuity was 35.6%(800 students). According to school type, in academic school, frequency of students with decreased visual acuity in day school was higher then that in night school. In commercial school, the frequency of students who had decreased visual acuity in night school were higher than that of students in day school. 3) As to variables influencing the decreased visual activity, there was a significant different between groups with normal visual acuity and groups with subnormal in terms of awareness of visual acuity by themself, parent's visual acuity, unbalanced eating habit, distance from television, or books, posture in watching television, posture in reading, awareness of illumination in classroom. 4) As to practice of protective and preventive health behavior for visual acuity care, In group with normal visual acuity. There was good practice such as proper eating habit, proper studying habit, and health habit in its descending order, but proper illumination and regular eye test were practiced poorly. In group with subnormal visual acuity, one of the vest practice in visual acuity care was an effort to prevent eye strain. Other good practice involve tasking regular eye test, maintaining proper studing habit, in its descending order.

• Asian-Australasian Journal of Animal Sciences
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• 제9권5호
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• pp.525-531
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• 1996

Nutritional status of minerals of beef and dairy cattle and buffalo in central Thailand were investigated by evaluating the mineral concentrations in feedstuff and blood plasma of animals. Three crossbred beef cow herds, a native cow herd, a buffalo female herd and 3 dairy cattle herds which consisted of the herds of lactating cows, dry cows and heifers were studied in both rainy and hot seasons. Low Na concentrations (<0.07% on a dry matter basis) in pasture samples from the fields for a cross bred beef cow were observed. Copper concentrations in all the pasture samples ranged from 3.7 to 13.5 mg/kg. Iron and Se concentration in pasture samples had a wide variety ranging from 185 to 1,345 and 0.033 to 1.127 mg/kg, respectively. The concentrations of K, Ca, Mg, P, Zn and Mn in total diets were higher than the requirements for beef and dairy cattle. Some animals with subnormal plasma Cu concentrations(< $0.65{\mu}g/ml$) existed in each herd. The animals which showed subnormal plasma Se concentrations(< $0.03{\mu}g/ml$) were observed in beef cow herds. The concentrations of Ca, Mg and Zn in plasma of animals were normal. Attention should be paid to the deficiencies in Na, Cu and Se of the animals in central Thailand.

• 한국학교보건학회지
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• 제6권1호
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• pp.58-68
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• 1993

This study was designed to grasp the knowledge and practice the level about visual impairment protective care of the primary school students and also analyse the state of visual impairment. The subjects of this study ware 347 students composed of 456 boys and 391 girls in primary school students. The data were collected by questionaire developed for the purpose of this study which has been made through studying references. These were carried out from the 10th to 30th of June 1992. Analysis of the data was done utilizing SPSS for percentage, mean, S.D., T-test., ANOVA and Pearson's Correlation Coefficient. The major results obtained from this study were as follows: 1. The level of the knowledge about visual impairment protective care was in intermediate range (mean on 20 point scale of 12.34, with O=definitely no), but low in aspects of preventive care for overwork of eye (mean on 5 point scale of 2.67). 2. The level of the practice about visual impairment protective care was intermediate range (mean on 20 point scale of 12.34, with O=definitely no), but low in aspects of preventive care for overwork of eye (mean on 5 point scale of 2.58). 3. Significant variables influencing knowledge of visual impairment protective care were sex (p<0.01) and grade (p<0.001). 4. Significant variables influencing practice of visual impairment protective care was living area (p<0.01). 5. Correlation between knowledge and practice: Those who have more knowledge score have more practice score (p<0.001). 6. vision impairment state 1) Student with subnormal in 0.9 or less were 26.3% in left eye and 28.4% in right eye. 2) Student with subnormal in 0.6 or less were 11.9% in left eye and 10.9% in right eye. 7. Vision impairment programs 1) Males are slightly higher in the degree of visual impairment than females. 2) Visual impairment were increased in accordance with the increase of grade. 3) Urban students are higher in the degree of visual impairment than rural students, but these seem to have no statistical meaning.

• 생물정신의학
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• 제2권2호
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• pp.287-294
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• 1995

A male patient with subnormal intelligence and schizoaffective symptoms was confirmed to have Klinefelter's syndrome with the karyotype of 47,XXY by the chromosomal analysis. He was shown to have a peculiar appearance of tall height, long extremities, gynecomastia and small ears. The hormonal study revealed decreased testosterone and increased FSH concentrations in the serum of the patient. He was also found to have small testes by the ultrasonography, which seemed to be sterile by the semen analysis. We reported this rare case and reviewed related articles.

• 대한수학회보
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• 제52권5호
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• pp.1481-1487
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• 2015

Let H be a separable complex Hilbert space. A commuting tuple $T=(T_1,{\cdots},T_n)$ of bounded linear operators on H is called a spherical isometry if $\sum_{i=1}^{n}T^*_iT_i=I$. The tuple T is called a toral isometry if each $T_i$ is an isometry. In this paper, we show that for each $n{\geq}1$ there is a supercyclic n-tuple of spherical isometries on $\mathbb{C}^n$ and there is no spherical or toral isometric tuple of operators on an infinite-dimensional Hilbert space.