• 대한전자공학회논문지SD
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• 제38권9호
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• pp.634-642
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• 2001

Buried channel 도파로와 ridge 도파로에 대하여 variational method (VM)과 유효굴절율 방법을 사용하여 2차원의 필드 분포를 구한 뒤 angular spectrum 방법을 적용하여 여러 개의 도파로 두께에 대하여 도파로 폭에 따른 단면 반사율을 계산하고 이를 비교 검토하였다. 도파로 폭에 따른 단면 반사율 변화량은 buried channel 도파로의 경우는 매우 크게 나타났으나 ridge 도파로의 경우는 buried channel 도파로의 변화량에 비해 매우 작게 나타났다. Angular spectrum 방법을 사용하여 채널 도파로 소자의 단면 반사율을 계산할 때 사용되는 2차원의 필드 분포의 정확성은 반사율 값에 큰 영향을 미침을 알 수 있었다. 유효굴절율 방법의 경우 도파로 폭과 도파로 두께가 감소할수록 필드 분포의 부정확성으로 인해 정확한 반사율 값과의 오차가 심하게 나타났다. 반면에 VM을 사용하여 구한 필드 분포는 도파로 폭과 두께에 관계없이 정확한 필드 분포와 오차가 적어 유효굴절율 방법보다 정확한 반사율 값을 구할 수 있었다. 유효굴절율 방법이 잘 적용되는 영역에서는 두 방법을 사용하여 구한 반사율의 차이가 매우 작음을 알 수 있었다.

• 한국간호교육학회지
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• 제11권2호
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• pp.214-221
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• 2005

Purpose: This study was to investigate the perception of the myopia in early school-aged children's mother and develope myopia preventive education program. Method: Data was collected from June 1th to 24th, 2003. The sample group(two elementary schools in A city)consisted of 105students mother with normal vision(naked vision 1.0 or more), 105 students mother with subnormal vision(0.7 or less). The data was analyzed using S.A.S. For the test of homogeneity and significance of variable, Fisher's Exact test and Student's t-test were used. Results: 1. There was significant difference in perception of being changed the children's eyesight between normal and myopia group(t=7.86, p=.0492). 2. High scores of cause of myopia were distance from TV or computer to viewer and time of watching TV or using computer in both groups. 3. There was significant difference in perception score of cause of myopia in the myopia group was 13.26, and 18.04 in the normal group(t=3.01, p=0.003). Especially in the unbalanced and regulated diet, regulated exercise, distance of eyes reading books and illumination, normal group had more perception score than myopia group. Conclusion: A myopia education program for children and parents should be planed and the effect be verified.

• 기본간호학회지
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• 제19권2호
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• pp.168-178
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• 2012

Purpose: The purpose of this study was to compare self-care behavior, diabetes-related stress and stress coping style among 3 blood glucose control groups (good, inadequate, and poor blood glucose control groups). Methods: Participants were 102 type 2 diabetic patients (good group: 41, inadequate group: 31, poor group: 30). Data were collected from Feb 19 to Mar 24, 2010 and were analyzed using Chi-square, Fisher's exact test and ANCOVA with SPSS/WIN 12.0. Results: Using ANCOVA with frequency of admission, and illness duration as covariates, significant differences were found among the 3 groups in self-care behavior (total score) and the exercise subscale. Using ANCOVA significant differences were found among 3 groups in diabetes-related stress (total score), emotional burden subscale and regimen distress subscale. Using ANCOVA no difference in stress coping was found among the 3 groups, but there was a significant difference in the problem-oriented coping subscale. Conclusions: Self-care behavior, diabetes-related stress, and stress coping style are factors influencing blood glucose control. The results of this study suggest that for improving blood glucose control, self care education program focused on diet and exercise in addition to stress management program for promoting problem oriented coping capability are recommended.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제22권2호
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• pp.159-168
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• 2015

Abstract. We propose a fast and robust finite difference method for Merton's jump diffusion model, which is a partial integro-differential equation. To speed up a computational time, we compute a matrix so that we can calculate the non-local integral term fast by a simple matrix-vector operation. Also, we use non-uniform grids to increase efficiency. We present numerical experiments such as evaluation of the option prices and Greeks to demonstrate a performance of the proposed numerical method. The computational results are in good agreements with the exact solutions of the jump-diffusion model.

• 응용통계연구
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• 제24권6호
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• pp.1161-1168
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• 2011

The approximation for the distribution functions of nonparametric test statistics is a significant step in statistical inference. A rank sum test for dispersions proposed by Ansari and Bradley (1960), which is widely used to distinguish the variation between two populations, has been considered as one of the most popular nonparametric statistics. In this paper, the statistical tables for the distribution of the nonparametric Ansari-Bradley statistic is produced by use of polynomially adjusted normal approximation as a semi parametric density approximation technique. Polynomial adjustment can significantly improve approximation precision from normal approximation. The normal-polynomial density approximation for Ansari-Bradley statistic under finite sample sizes is utilized to provide the statistical table for various combination of its sample sizes. In order to find the optimal degree of polynomial adjustment of the proposed technique, the sum of squared probability mass function(PMF) difference between the exact distribution and its approximant is measured. It was observed that the approximation utilizing only two more moments of Ansari-Bradley statistic (in addition to the first two moments for normal approximation provide) more accurate approximations for various combinations of parameters. For instance, four degree polynomially adjusted normal approximant is about 117 times more accurate than normal approximation with respect to the sum of the squared PMF difference.

• 응용통계연구
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• 제21권1호
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• pp.177-182
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• 2008

공통분산을 갖는 두 모집단에서 얻은 두 독립표본 자료로부터 공통분산을 추정하거나, 한 모집단에서 얻는 두 자료의 혼합자료로부터 모분산을 추정할때 각 표본분산의 가중평균값인 합동추정량(pooled estimator)을 주로 사용한다. 본 논문에서는 동일한 모집단에서 얻은 혼합자료의 표본분산 식을 각 자료의 평균과 분산만 이용하여 구한 후 합동추정량과 비교한다.

• 대한간호학회지
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• 제41권2호
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• pp.175-181
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• 2011

Purpose: This study was conducted to identify endotracheal colonization and the incidence of ventilator-associated pneumonia related to the type of endotracheal suction system. Methods: The participants in this study were ICU patients hospitalized between October 2009 to March 2010 who used ventilators for over 48 hr with closed (CSS, n=30) or open (OSS, n=32) suction systems. To standardize the pre-intervention suction system, a suctioning protocol was taught to the ICU nurses. Collected data were analyzed using ${\chi}^2$-test, Fisher's exact test, Wilcoxon rank sums test, Wilcoxon test, Log-rank test and Poisson regression. Results: Endotracheal colonization was higher in OSS than CSS from day 1 to day 8 while using a ventilator and there was a significant difference between the two groups. The CSS reached 50% of endotracheal colonization by the 4th day, whereas for the OSS, it was the 2nd day (p=.04). The incidence of ventilator-associated pneumonia showed no significant difference. Conclusion: For patients with a high risk of pneumonia, CSS must be used to lower endotracheal colonization.

• 치과방사선
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• 제21권1호
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• pp.127-135
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• 1991

This study purports to make in consideration of the recent xeroradiographic development an exact analysis, by comparison, of conventional cephalometry and xeroradiographic cephalometry that are indispensably utilized in the field of orthodontics as a means of cephalometric measuring For that purpose attached to ten landmarks on a dry skull was a lead ball, a radio-opaque substance, and projected X-ray beam one time each by means of the two methods, and then ten times each without change of locations of the skull, in the state in which the lead ball was removed. These data were committed to ten dentists for tracing to determine a difference between the same kind of cephalometries. A computerized statistic analysis of the data shows findings, as follows: 1. Conventional cephalometry shows higher accuracy in Nasion, as compared with xeroradiographic cephalometry. 2. Xeroradiographic cephalometry is found more accurate in Anterior Nasal Spine, 'A' Point, Pogonion, Gonion, Porion, Prosthion and Orbitale than conventional cephalometry. 3. There is no difference between both methods in Basion. 4. At test between the two methods by all the dentists reveals that xeroradiographic cephalometry is more accurate than conventional cephalometry.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.249-257
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• 2007

A high resolution numerical method aimed at solving gas-liquid two-phase flow is proposed and applied to gas-liquid two-phase shock tube problem. The present method employs a finite-difference 4th-order Runge-Kutta method and Roe's flux difference splitting approximation with the MUSCL TVD scheme. By applying the homogeneous equilibrium cavitation model, the present density-based numerical method permits simple treatment of the whole gas-liquid two-phase flow field, including wave propagation and large density changes. The speed of sound for gas-liquid two-phase media is derived on the basis of thermodynamic relations and compared with that by eigenvalues. By this method, a Riemann problem for Euler equations of one dimensional shock tube was computed. Numerical results such as detailed observations of shock and expansion wave propagations through the gas-liquid two-phase media and some data related to computational efficiency are made. Comparisons of predicted results and exact solutions are provided and discussed.

• 한국전산유체공학회지
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• 제12권2호
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• pp.53-62
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• 2007

A high resolution numerical method aimed at solving cavitating flow is proposed and applied to gas-liquid two-phase shock tube problem. The present method employs a finite-difference 4th-order Runge-Kutta method and Roe's flux difference splitting approximation with the MUSCL TVD scheme. By applying the homogeneous equilibrium cavitation model, the present density-based numerical method permits simple treatment of the whole gas-liquid two-phase flow field, including wave propagation and large density changes. The speed of sound for gas-liquid two-phase media is derived on the basis of thermodynamic relations and compared with that by eigenvalues. By this method, a Riemann problem for Euler equations of one dimensional shock tube was computed. Numerical results such as detailed observations of shock and expansion wave propagations through the gas-liquid two-phase media at isothermal condition and some data related to computational efficiency are made. Comparisons of predicted results and exact solutions are provided and discussed.