• Journal of Integrative Natural Science
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• v.11 no.3
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• pp.154-160
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• 2018

Consider the problem of estimating a $p{\times}1$ mean vector ${\theta}(p-r{\geq}3)$, r = rank(K) with a projection matrix K under the quadratic loss, based on a sample $Y_1$, $Y_2$, ${\cdots}$, $Y_n$. In this paper a James-Stein type estimator with shrinkage form is given when it's variance distribution is specified and when the norm ${\parallel}{\theta}-K{\theta}{\parallel}$ is constrain, where K is an idempotent and symmetric matrix and rank(K) = r. It is characterized a minimal complete class of James-Stein type estimators in this case. And the subclass of James-Stein type estimators that dominate the sample mean is derived.

• MALSORI
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• no.40
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• pp.91-104
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• 2000

생성음운론의 입장에서 본 Hyman 가설을 적용할 때 영어와 한국어에 공통으로 나타나는 영어 분절음 $/p^h,{\;}t^h,{\;}k^ h/$는 한국어 화자에게서 그대로 인식되며, 영어에는 있지만 한국어에 없는 /f, v, $\theta$/는 관련 음운 규칙이 적용되어 한국어음과 유사하게 된 $[/p^h]$], [p], [s]로 각각 인식된다고 설명했다. 이와 같은 Hyman 가설의 적용은 /f, v, $\theta$/가 왜 한국어에서 존재하지 않고 관련 음운규칙이 적용된 형태로 나타나는 지에 대한 이유를 제시하지 못하는 한계가 있다. 그러나 최적성 이론에서는 입력형에서 모든 분절음을 받아들이고 언어간 제약등급의 차이로 /f, v, $\theta$/와 같은 분절음이 한국어에서 나타나지 않고 [p, t, k]로 나타난다고 설명하였다. 따라서 최적성 이론은 영어 분절음이 한국어에서 나타나는 다양한 양상을 적절히 설명할 수 있음을 보여 주고 있다.

• Journal of the Korean Data and Information Science Society
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• v.15 no.4
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• pp.993-1002
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• 2004

Imputation procedures such as fully efficient fractional imputation(FEFI) or multiple imputation(MI) can be used to construct complete contingency tables from samples with partially classified responses. Variances of FEFI estimators of population proportions are derived. Simulation results, when data are missing completely at random, reveal that FEFI provides more efficient estimates of population than either multiple imputation(MI) based on data augmentation or complete case analysis, but neither FEFI nor MI provides an improvement over complete-case(CC) analysis with respect to accuracy of estimation of some parameters for association between two variables like $\theta_{i+}\theta_{+i}-\theta_{ij}$ and log odds-ratio.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.5
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• pp.57-65
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• 1996

초고속 정전유도형 정전전동기의 개발의 위한 기초연구로서 회전자 물질의 표면저항률, 비유전율 및 전하완하시정수의 변화에 따른 회전자의 회전속도특성을 조사하였다. 회전자표층물질의 비유전율 및 표면저항률은 클수록 회전자의 회전속도는 증가하였으며, 또한 이 두 요소를 곱한 회전지표면에 유도된 전하의 완화시정수가 클수록 회전속도는 증가하였다. 한편 회전자표층물질로서 도전성물질(Ti)을 폴리프로필렌 위에 불연속적으로, 즉 띠의 모양으로 증착한 시료를 사용하여 띠의 폭 및 경사각의 변화에 따른 회전자의 회전속도특성 및 토크 특성을 조사하였다. 이 경우 띠의 폭이 적어질수록 회전자의 회전수는 지수함수적으로 증가하였으며, 등간격으로 세분화한 것을 회전자의 축에 대해서 회전방향으로 경사각$\theta$만큼 기울였을 때 $\theta$=60。 및 150。일 때 회전자의 회전속도가 가장 큰 것으로 나타났으며, 특히 경사각 $\theta$=0。일때에 비해서 약 125[%]정도 높은 회전속도를 보였다. 최대토크 및 최대출력은 각각 {{{{25$\times$ { 10}^{ -6} [Nm]}}}}및 11.5[mW]이었다.

• Korean Journal of Materials Research
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• v.9 no.2
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• pp.111-116
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• 1999

The microstructure of vitreous bonded abrasives, which are used as the essential materials in the precise grinding, was investigated theoretically using two particle model. In this paper, a general equation applicable for a case in which there is a gap between abrasive grits is suggested. As a result, it was known that both the volume ratio of grit to glassy bond(V\ulcorner/V\ulcorner) and porosity(V\ulcorner) are the function of $\alpha$(the ratio of distance between grit to diameter of grit) and $\theta$(the angle from the center of pore to that of grit). Because the value $\alpha$ and $\theta$ can be get easily by using these suggested equations, the microstructure could be explained quantitatively. Also the raised error with the increasing amount of bond was modified by the simple assumption. As a result, in that case, both V\ulcorner/V\ulcorner and V\ulcorner were known to be the function of $\alpha$ and $\theta$(the ratio diameter of pore to that of grit).

• Proceedings of the KOSOMBE Conference
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• v.1989 no.05
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• pp.45-49
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• 1989

In this paper the feature of background EEG is extracted by LS Prony Method for the analysis of background EEG in the time domain. From the experimential results the alpha band amplitude is the largest among bands and beta band amplitude is larger than that of the delta band and theta band. The sustained time for the alpha band, the beta band, the delta band and the theta band is 2.3461(sec), 1.8980(sec), 0.3120(sec), 0.2930(sec) respectively. Consequently the alpha band and the beta band are maintained in the whole, segment. The delta band, the theta band are existed intermittently in the segment.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.4
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• pp.33-41
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• 1995

This study includes thermal plasticity analyses for a turbine rotor with the simple geometry and the boundary conditions. When centrifugal or thermal stress are applied at the high temperature material of engine blade, stress distributions I material ($\sigma$${\gamma}$${\gamma}$, $\sigma$$\theta$$\theta$, $\tau$${\gamma}$$\theta$, Mises stress) are analyzed by computer simulation(ABQUS) as followings; 1. The maximum stress at the radial direction() is applied at the upper middle part of spline hole. 2. The maximum stress at the tangential direction() is applied at the upper right boundary of spline hole. 3. The maximum shear stress () in () direction is applied at the upper middle part of spline hole. 4. The maximum Mises stress is applied at the upper right boundary of spline hole. This stress is due to the critical stress by which rotor can be fractured according to elapsed time.

• Journal of the Korean Statistical Society
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• v.24 no.2
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• pp.337-347
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• 1995

In the problem of some sequential estimation, the stopping times may be written in the form $N(c) = inf{n \geq n_0; n \geq c^2 S^2_n/\delta^2 (\bar{X}_n)}$ where ${s^2_n}$ and ${\bar{X}_n}$ are the sequences of sample variance and sample mean of the independently and identically distributed (i.i.d.) random variables with distribution $F_{\theta}(x), \theta \in \Theta$, respectively, and $\delta$ is either constant or any given positive real valued function. We obtain some asymptotic normality and asymptotic expectation of the N(c) in various limiting situations. Specially, uniform asymptotic normality and uniform asymptotic expectation of the N(c) are given.

• Communications of Mathematical Education
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• v.18 no.1 s.18
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• pp.257-266
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• 2004

자연의 세계에서 나뭇잎, 돌기물, 구름, 해안선, 곤충의 모습 등에 내재하고 있는 아름다움은 흔히 균형성, 대칭성, 다양성 등으로부터 비롯된다. 자연 현상은 복소수를 활용하여 극좌표 표현으로 묘사되는 경우가 많다. 본 논문에서는 1989년 Temple H. Fay가 Amer. Math. Monthly 96(5)호에서 발표한 나비곡선 r= e$^{cos{\theta}}$-2cos4${\theta}$+sin$^5$($\frac{\theta}{12}$)의 기하학적 성질을 대칭 이동, 회전 이동, 수치적분, 미분, 극좌표계, 삼각함수, 지수함수 및 매개함수의 표현 등 고등학교 및 대학의 미적분학 관점에서 살펴 보고 극좌표 도형에 관한 흥미 유발과 더불어 컴퓨터 활용 방법을 제시하기로 한다. 수학전문 소프트웨어인 매스매티카를 활용하여 나비곡선의 작도 및 기하학적 성질을 분석하고자 한다.

• Korean Journal of Acupuncture
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• v.36 no.4
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• pp.241-251
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• 2019

Objectives : The purpose of this study was to examine the effects of electroacupuncture at GB14, on brain activity assessed on an electroencephalogram(EEG). Methods : (1) Thirty-four healthy participants were randomly divided into two groups, receiving either real acupuncture or non-penetrating sham acupuncture at GB14. (2) EEG measurements were conducted simultaneously before and after a 5-minute electroacupuncture stimulation, and the differences in the resulting EEG parameters were compared between the test and control groups. Results : (1) Absolute power increased significantly in the theta-wave channel of the occipital region and in the entire alpha-wave channel. (2) Relative power decreased significantly in the theta-wave channels of the frontal and occipital regions. (3) Coherence decreased significantly in the theta- and beta-wave channels of the parietal and occipital regions, and increased significantly in the alpha-wave channels of most areas. Conclusions : This study shows that electroacupuncture stimulation at GB14 activates the alpha frequency band in particular.