• Journal of applied mathematics & informatics
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• 제38권1_2호
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• pp.175-187
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• 2020

Recently Salkuyeh and Rahimian in (Comput. Math. Appl. 74 (2017) 2940-2949) proposed a modification of the generalized shift-splitting (MGSS) method for solving singular saddle point problems. In this paper, we present the spectral analysis of the MGSS preconditioner when it is applied to precondition the singular saddle point problems with the (1, 1) block being symmetric. Some eigenvalue bounds for the spectrum of the preconditioned matrix are given. We show that all the real eigenvalues of the preconditioned matrix are in a positive interval and all nonzero eigenvalues having nonzero imaginary part are contained in an intersection of two circles.

• Architectural research
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• 제2권1호
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• pp.47-54
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• 2000

The critical load of a continuous compression member was determined by the beam-analogy method. The proposed method utilizes the stress-analysis results of the analogous continuous beam, where imaginary concentrated lateral load changing its direction is applied at each midspan. The proposed method gives a lower bound error of critical load and can predict the span that buckles first. The effective length factors for braced frame columns can be easily determined by the present method, but result in the upper bound errors in all cases, which can lead to a conservative structural design.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제6권1호
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• pp.30-37
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• 2003

This paper describes vibration control of a suspended system using wave absorption method. A moving multiple-pendulum system and a moving wire-and-load system are treated. The wire-and-load system is extended to a model crane system that has a motor system to roll up and down the suspended mass like a real crane. The same program with different parameter values controls these three systems. Both numerical simulation and experiment have been conducted, and the present control method has shown to be quite effective.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권6호
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• pp.272-282
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• 2001

This paper developed improved fast Walsh transform based on dyadic-ordered fast Walsh transform, then regenerated signal flow graph of improved fast Walsh transform, and used it for digital filtering, and then measured fundamental frequency and harmonics for current and voltage signals of power system. Using the improved fast Walsh transform, we present a new algorithm which reduces the computational amount, and it can consequently calculate the real and imaginary components for current and voltage signals of power system in sampling intervals. The calculation amount is reduced to 2(N-1) at N samples to measure full harmonics using developed algorithm. When, in single harmonic measuring, it needs only 2(log2N-1) additions and subtractions.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.463-468
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• 1997

This paper presents a theoretical approach of the instability criterion from stratified to nonstratified flow in horizontal pipe at cocurrent flow conditions. The new theoretical instability criterion for the stratified and nonstratified flow transition in horizontal pipe has been developed by hyperbolic equations in two-phase flow, Critical flow condition criterion and onset of slugging at cocurrent flow condition correspond to zero and imaginary characteristics which occur when the hyperbolicity of a stratified two-phase flow is broken, respectively. Through comparison between results predicted by the present theory and the Kukita et al.[1] experimental data of pipes, it is shown that they are in good agreement with data.

• 아동학회지
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• 제33권1호
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• pp.133-145
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• 2012

The present study systematically analyzed the relationships between children's emotional and behavioral problems, attachment, fears and coping behaviors. The subjects of this study were 63 school-aged children residing in Seoul, Gwangiu and South Jeolla province. The findings indicated that emotional and behavioral problems were negatively correlated to children's attachments to their fathers and peers. The children's attachment to peers had a significant correlation as well as behavioral problems and coping strategies used by children in stressful situations. Emotional problems were explained by fears of realistic objects, the seeking out of social support, mother and father attachment, and fears of imaginary objects. In addition, behavioral problems were explained by aggressive coping behaviors and child-father attachment.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1369-1378
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• 2017

The present paper reports the development of a computational code based on the Adaptive Group of Ink Drop Spread (AGIDS) for reconstruction of the neutron noise sources in reactor cores. AGIDS algorithm was developed as a fuzzy inference system based on the active learning method. The main idea of the active learning method is to break a multiple input-single output system into a single input-single output system. This leads to the ability to simulate a large system with high accuracy. In the present study, vibrating absorber-type neutron noise source in an International Atomic Energy Agency-two dimensional reactor core is considered in neutron noise calculation. The neutron noise distribution in the detectors was calculated using the Galerkin finite element method. Linear approximation of the shape function in each triangle element was used in the Galerkin finite element method. Both the real and imaginary parts of the calculated neutron distribution of the detectors were considered input data in the developed computational code based on AGIDS. The output of the computational code is the strength, frequency, and position (X and Y coordinates) of the neutron noise sources. The calculated fraction of variance unexplained error for output parameters including strength, frequency, and X and Y coordinates of the considered neutron noise sources were $0.002682{\sharp}/cm^3s$, 0.002682 Hz, and 0.004254 cm and 0.006140 cm, respectively.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.275-280
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• 2008

Shock tube flow measurement has been often troubled with a finite opening time of diaphragm, but there is no systematic work to investigate its effect on the shock tube flow. In the present study, both the experimental and computational works have been performed on the shock tube flows at low pressure ratios. The computational analysis has been performed using the two-dimensional, unsteady, compressible Navier-Stokes equations, based upon a TVD MUSCL finite difference scheme. It is known that the present computational results reproduce the experimental data with good accuracy and simulate successfully the process of diaphragm opening as a function of time. The concept of an imaginary center is introduced to specify the non-centered expansion wave due to a finite opening time of diaphragm. The results obtained show that the diaphragm opening time is reduced as the initial pressure ratio of shock tube increases, leading to the effect of a finite opening time of diaphragm to be more remarkable at low pressure ratios.

• Advances in materials Research
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• 제1권4호
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• pp.285-297
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• 2012

The present study addresses the problem of quantitative prediction of effective complex relative permittivity of Barium Titanate/Polyvenylidene Fluoride (PVDF) and $(Bi_{0.5}Na_{0.5})_{0.94}Ba_{0.06}TiO_3$/Poly(VDF-TrFE) biphasic ceramic-polymer composites. Theoretical results for effective relative permittivity derived from several dielectric mixture equations were fitted to the experimental data taken from the works of Prasad et al. (2010), Wang et al. (2004), Takenaka et al. (1991) and Yamada et al. (1982). The study revealed that out of the different test equations, only a few equations like modified Rother-Lichtenecker equation, Dias-Dasgupta equation or Rao equation for the real part and Bruggeman equation for the imaginary part of complex permittivity well fitted the corresponding experimental results. In the present study, some of the equations were used in their original forms, while some others were modified by choosing suitable shape-dependent parameters in order to get reasonably good agreement with experimental results. Besides, the experimental results have been proposed in the form of a mathematical model using first order exponential growth, which provided excellent fits.

• 영재교육연구
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• 제13권3호
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• pp.87-120
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• 2003

영재교육은 개인이 가진 능력을 최대한 계발하여 자아를 실현하고, 국가 사회가 필요로 하는 인재 육성의 육성이라는 점에서 그 중요성이 강조되어 왔다. 영재교육이 활성화되기 위해서는 제도적인 측면과 함께 그들의 능력수준과 학습욕구에 적합한 영재교육 프로그램이 개발되어야 한다. 이 연구에 참여한 언어 영재 학생은 총 60명인데, 이 중에서 예비 연구에 참여한 30명은 연구자가 개발한 심화학습 프로그램과 언어 문제해결력 검사의 양호도를 평가하기 위한 대상이었고, 실험집단 30명은 10명씩 세 집단으로 나누어 각 집단에 한국교육 개발원 교재, 연구자가 개발한 심화학습 프로그램, 국어 교과서 심화학습 프로그램에 배정하여 프로그램간의 유의도를 비교 검증하였다. 결과를 종합하면, 언어 영재학생에게 연구자가 개발한 체계화된 개별화 심화학습 프로그램을 제공하면 언어 창의적 문제해결력이 향상됨을 알 수 있었다. 한국교육개발원 언어 영재 교재나 국어 교과서 심화학습도 언어 영재에게 읽기 능력을 향상시키는 데 약간의 효과는 있지만, 언어 이해 능력과 언어 표현 능력을 효율적으로 발달시키는 데는 효과가 없는 것으로 나타났다. 한국교육개발원 언어 영재교재나 국어 교과서 심화학습 내용처럼 듣기, 말하기, 읽기와 쓰기를 따로 분리해서 지도하는 것보다 일상생활처럼 듣기, 말하기, 읽기, 쓰기를 종합해서 함께 지도하는 것이 언어적으로 재능있는 영재에게는 더 효과적이라고 나타났다. 또한 지역이나 학교 급별에 따라 언어 영재성의 개념이 달라질 수 있으므로, 그에 알맞은 언어 영재 심화학습 프로그램을 지속적으로 개발할 필요가 있는 것으로 나타났다.