• Journal of the Korean Statistical Society
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• v.25 no.1
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• pp.153-159
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• 1996

Sums of independent random variables $S_n = X_1 + X_ + cdots + X_n$ are considered, where the X$_{n}$ are chosen according to a stationary process of distributions. Given the time t .geq. O, let N (t) be the number of indices n for which O < $S_n$ $\geq$ t. In this set up we prove that N (t)/t converges almost surely and in $L^1$ as t longrightarrow $\infty$, which generalizes classical renewal theorem.m.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.145-150
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• 2000

The adaptation for a right source on the retina consists of the light-dark adaptation's two curves for a time by the rod-cone receptor. We obtained the adaptation for a time to measure the threshold intensities, it was two decay curves by the center of a rod-cone break. It could be represented the dark adaptation by a exponential decay function consisting of $T_{min}$, $a_r$, $a_c$, $T_{0(r)}$, $T_{0(c)}$, $t_b$, $t_c$'s parameters. The curves of a $t_b$ below and a $t_b$ above showed the adaptation sensitivity of the cone and the rod. The exponential decay function was well applied to the dark adaptation in difference retinal positions, in contrally fixated fields, in luminous, as age etc. It could be used the decay parameter as the index because of representing the properties of the dark adaptation's function.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.36.3-37
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• 2009

This is an attempt to improve a formula to predict variations of geomagnetic storm indices (Dst) from solar wind parameters. A formula which is most widely accepted was given by Burton et al. (1975) over 30 years ago. Their formula is: dDst*/dt = Q(t) - Dst*(t)/$\tau$, where Q(t) is the Dst injection rate given by the convolution of dawn-to-dusk electric field generated by southward solar wind magnetic field and some response function. However, they did not clearly specify the response function. As a result, misunderstanding seems to be prevailing that the injection rate is proportional to the dawn-to-dusk electric field. In this study we tried to determine the response function by examining 12 intense geomagnetic storms with minimum Dst < -200 nT for which solar wind data are available. The method is as follows. First we assume the form of response function that is specified by several time constants, so that we can calculate the injection rate Q1(t) from the solar wind data. On the other hand, Burton et al. expression provide the observed injection rate Q2(t) = dDst*/dt + Dst*(t)/$\tau$. Thus, it is possible to determine the time constants of response function by a least-squares method to minimize the difference between Q1(t) and Q2(t). We have found this simple method successful enough to reproduce the observed Dst variations from the corresponding solar wind data. The present result provides a scheme to predict the development of Dst 30 minutes to 1 hour in advance by using the real time solar wind data from the ACE spacecraft.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.475-484
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• 2005

Let W(t) be a Wiener path, let $\xi\;:\;[0,\;{\infty})\;\to\;\mathbb{R}$ be a continuous and increasing function satisfying $\xi$(0) > 0, let $$T_{/xi}=inf\{t{\geq}0\;:\;W(t){\geq}\xi(t)\}$$ be the first-passage time of W over $\xi$, and let F denote the distribution function of $T_{\xi}$. Then the first passage problem has a unique continuous solution as following $$F(t)=u(t)+{\sum_{n=1}^\infty}\int_0^t\;H_n(t,s)u(s)ds$$, where $$u(t)=2\Psi(\xi(t)/\sqrt{t})\;and\;H_1(t,s)=d\Phi\;(\{\xi(t)-\xi(s)\}/\sqrt{t-s})/ds\;for\;0\;{\leq}\;s.

• The Korean Journal of Rehabilitation Nursing
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• v.14 no.1
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• pp.54-61
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• 2011

Purpose: The purpose of this study was to examine the effects of a day care rehabilitation program managed by nurses on physical and emotional function of patients with job-related injuries. Method: A one group pre-test and post-test quasi-experimental design was used. Thirty patients participated in a day care rehabilitation program and 9% of those were unable to complete the 16 weeks program due to absence. The physiotherapist, occupational therapist, and clinical psychologist offered the day care rehabilitation program, 5 times a week for 16 weeks. Outcome measures included physical and emotional function. Results: The program participants had significantly greater motor function (t=-2.85, p=.008) and activity of daily living (t=-5.34, p<.001), and lower depression (t=5.20, p<.001), state anxiety (t=4.71, p<.001), and trait anxiety (t=4.40, p<.001). Conclusion: The nurse managed day care rehabilitation program significantly improved physical and emotional function in patients with job-related injuries. The program should be further tested in a larger sample to validate the findings.

• The Korean Journal of Rehabilitation Nursing
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• v.13 no.2
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• pp.161-170
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• 2010

Purpose: This study was to confirm the influence of memory intensive training program on the elderly people's cognitive function, memory performance, and self-esteem. Method: Using a quasi-experimental or experimental design, 60 elderly aged over 60 years randomly assigned the experimental and control groups completed pretest-post evaluation. The experimental group participated in the memory intensive training program was offered to the participants in the experimental group for three weeks (2times/week). The t-test and $X^2$-test using SAS program. Results: 1) The cognitive function was significantly higher in the experimental group compared to that in the control group (t=3.26, p=.002). 2) The memory performance that included immediate word recall tasks, word recognition tasks and delayed word recall tasks was significantly higher in the experimental group than in the control group (t=5.30, p<.001). The experimental group showed significantly higher scores for memory performance than the control group (t=5.30, p<.001). 3) The self-esteem was higher in the experimental group than in the control group, but there was no significant difference between the two groups (t=1.94, p=.058). Conclusion: The Memory Intensive Training Program could be an effective intervention for improving cognitive function, and memory performance of the elderly people.

• Communications of the Korean Mathematical Society
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• v.31 no.4
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• pp.683-693
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• 2016

In [1], the authors proved that the finite union of linear star-configurations in $\mathbb{P}^2$ has a generic Hilbert function. In this paper, we find the minimal graded free resolution of the union of two linear star-configurations in $\mathbb{P}^2$ of type $s{\times}t$ with $\(^t_2\){\leq}s$ and $3{\leq}t$.

• Bulletin of the Korean Mathematical Society
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• v.58 no.2
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• pp.515-526
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• 2021

Denote by ��+ the set of probability measures supported on ℝ+. Suppose V�� is the variance function of the Cauchy-Stieltjes Kernel (CSK) family ��-(��) generated by a non degenerate probability measure �� ∈ ��+. We determine the formula for variance function under boolean multiplicative convolution power. This formula is used to identify the relation between variance functions under the map ${\nu}{\mapsto}{\mathbb{M}}_t({\nu})=({\nu}^{{\boxtimes}(t+1)})^{{\uplus}{\frac{1}{t+1}}}$ from ��+ onto itself.

• Journal of applied mathematics & informatics
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• v.27 no.1_2
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• pp.183-194
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• 2009

In this paper, we considered the following four-point boundary value problem $\{{x"(t)+h(t)f(t,x(t),x'(t))=0,\;0<t<1\atop%20x'(0)=ax(\xi),\;x'(1)=bx(\eta)}\$. where $0\;<\;{\xi}\;<\;{\eta}\;<\;1,\;{\delta}\;=\;ab{\xi}\;-\;ab{\eta}\;+\;a\;-\;b\;<\;0,\;0\;<\;a\;<\;\frac{1}{\xi},\;0\;<\;b\;<\;\frac{1}{\eta}$. After the discussion of the Green function of the corresponding homogeneous system, we establish some criteria for the existence of positive solutions by using the generalized Leggett-William's fixed point theorem. The interesting point is the expression of the Green function, which is a difficulty for multi-point BVP.

• East Asian mathematical journal
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• v.35 no.1
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• pp.67-75
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• 2019

We investigate the averaging value of a random sampling of a Dirichlet series with some condition using Poisson distribution. Our result is the following: Let $L(s)={\sum}^{\infty}_{n=1}{\frac{a_n}{n^s}}$ be a Dirichlet series that converges absolutely for Re(s) > 1. If $X_t$ is an increasing random sampling with Poisson distribution and there exists a number $0<{\alpha}<{\frac{1}{2}}$ such that ${\sum}_{n{\leq}u}a_n{\ll}u^{\alpha}$, then we have $${\mathbb{E}}L(1/2+iX_t)=O(t^{\alpha}{\sqrt{{\log}t}})$$, for all sufficiently large t in ${\mathbb{R}}$. As a result, we get the behaviour of $L({\frac{1}{2}}+it)$ such that L is a Dirichlet L-function or a modular L-function, when t is sampled by the Poisson distribution.