• 한국통신학회논문지
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• 제12권3호
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• pp.254-266
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• 1987

분할법은 대규모회로망을 부분회로망으로 나누어서 해석하는 것으로 그 개념은 개회로와 폐회로에 대한 그래프 이론에 근거를 두고 있다. 본 논문에서는 대형회로망 고유값의 특성방정식을 분할법에 의하여 수식화 하고 반복법을 적용하여 간편하게 특성방정식의 해를 구함으로서 분할하지 않고 해석하는 방법에 비하여 효율적으로 처리할 수 있었다.

• 제어로봇시스템학회논문지
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• 제16권1호
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• pp.1-4
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• 2010

Based on the sliding mode control theory, a decentralized controller design method is developed for a large scale system with a poly topic model. In terms of LMIs, we derive sufficient conditions for the existence of the decentralized controller guaranteeing a stable sliding motion. We also give an LMI-based control design algorithm. Finally, the proposed method is applied to decentralized stabilization of double-inverted pendulums. Simulation results show that our method gives not only the robust stability but perfect rejection of norm-bounded uncertainties.

• 센서학회지
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• 제18권3호
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• pp.197-201
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• 2009

This paper studies on the noncontact displacement sensor system to detect the displacement of the cylinder rod. For an inexpensive and a simple process, magnetic scales are printed on the cylinder rod, and magnetized by the specially designed magnetizer that has an yoke through the alternation of N and S pole. Noncontact displacement sensor system consists of cylinder with magnetic scales, Hall sensor, linear guide, controller and display. The system can detect the displacement of moving cylinder with 5 cm/sec in the case of 1 mm magnetic scale. It shows a possibility of position detection of hydraulic cylinder and air cylinder.

• 전기학회논문지
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• 제61권7호
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• pp.1014-1018
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• 2012

This paper presents a decentralized controller design for formation flying of multiple satellites based on the overlapping decomposition technique. Each satellite is assumed to avail only the information of its own and in front of itself, which restricts the structure of a controller gain matrix to an overlapped form. The concerned large-scale system is expanded using the overlapping decomposition technique. Design condition is represented in terms of linear matrix inequalities with small-scale systems in a decentralized form, based on the expanded system. The resulting controller is contracted to the original overlapped form so as to close the original system. A numerical simulation shows the effectiveness of the proposed technique.

• Computers and Concrete
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• 제16권4호
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• pp.531-544
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• 2015

The objective of this study was to examine the effect of repair mortar on the dynamic properties such as natural frequencies, mode shape and damping ratios of two story single span scale reinforced concrete building. To this end, two story single span scale reinforced concrete building having dimensions of 150 cm (width), 150 cm (length) and 135 cm (height) was constructed. Workmanship defects such as separation of material, faulty vibration application and bad gradation of the structure were properly evaluated. Dynamic properties of damaged structure were experimentally determined using Operational Modal Analysis (OMA). Detected defects in the structure were fixed by plastering with repair mortar. Dynamic properties of repaired structure were reevaluated by using the OMA method. Finite element software called Abaqus was used to numerically determine dynamic properties of the structure. Structure modeled as solid was subjected to Linear Perturbation Frequency Method. The changes in dynamic properties of structure after the repair process were comparatively studied by evaluating experimental and numerical results.

• Advances in nano research
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• 제13권1호
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• pp.63-75
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• 2022

The nonlinear dynamic behavior of a nonuniform small-scale nonlocal beam is investigated in this work. The nanobeam is theoretically modeled using the nonlocal Eringen theory, as well as a few of Von-nonlinear Kármán's theories and the classical beam theory. The Hamilton principle extracts partial differential equations (PDE) of an axially functionally graded (AFG) nano-scale beam consisting of SUS304 and Si₃N₄ throughout its length, and an elastic Winkler-Pasternak substrate supports the tapered AFG nanobeam. The beam thickness is a function of beam length, and it constantly varies throughout the length of the beam. The numerical solution strategy employs an iteration methodology connected with the generalized differential quadratic method (GDQM) to calculate the nonlinear outcomes. The nonlinear numerical results are presented in detail to examine the impact of various parameters such as nonlinear amplitude, nonlocal parameter, the component of the elastic foundation, rate of cross-section change, and volume fraction parameter on the linear and nonlinear free vibration characteristics of AFG nanobeam.

• 천문학회지
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• 제29권spc1호
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• pp.19-21
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• 1996

We apply topological measures of clustering such as percolation and genus curves (PC & GC) and shape statistics to a set of scale free N-body simulations of large scale structure. Both genus and percolation curves evolve with time reflecting growth of non-Gaussianity in the N-body density field. The amplitude of the genus curve decreases with epoch due to non-linear mode coupling, the decrease being more noticeable for spectra with small scale power. Plotted against the filling factor GC shows very little evolution - a surprising result, since the percolation curve shows significant evolution for the same data. Our results indicate that both PC and GC could be used to discriminate between rival models of structure formation and the analysis of CMB maps. Using shape sensitive statistics we find that there is a strong tendency for objects in our simulations to be filament-like, the degree of filamentarity increasing with epoch.

• 한국멀티미디어학회논문지
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• 제7권2호
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• pp.164-172
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• 2004

그레이스케일 영상을 이진 영상으로 변환하는 방법을 해프토닝이라 한다. 이런 방법 중 오차확산방법은 그레이스케일 영상을 이진 영상으로 표현할 때 우수한 화질을 보이지만 웜 현상, 뭉쳐짐 현상 등의 단점이 있다. 이런 단점을 보완하는 방법 중 하나가 임계값 변조 방법이다. 본 논문에서는 영상의 국부적인 특성을 고려한 임계값 변조치를 적용한다. 먼저 원영상과 해프토닝 영상의 선형이득을 이용해 평탄영역에 대한 오차를 최소화하는 임계값 변조치를 구한다. 그리고 이 값들에 경계정보에 따른 보정 값을 주어 경계영역을 표현한다. 제안방법은 해프토닝시 발생하는 오차를 줄여 오차로 인해 발생하는 영상내의 뭉쳐짐 현상과 웜 현상 등을 최소화하여 기존의 방법에 비해 더 좋은 화질을 얻을 수 있다.

• Smart Structures and Systems
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• 제22권1호
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• pp.105-120
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• 2018

In this paper, the nonlinear free and forced vibration responses of sandwich nano-beams with three various functionally graded (FG) patterns of reinforced carbon nanotubes (CNTs) face-sheets are investigated. The sandwich nano-beam is resting on nonlinear Visco-elastic foundation and is subjected to thermal and electrical loads. The nonlinear governing equations of motion are derived for an Euler-Bernoulli beam based on Hamilton principle and von Karman nonlinear relation. To analyze nonlinear vibration, Galerkin's decomposition technique is employed to convert the governing partial differential equation (PDE) to a nonlinear ordinary differential equation (ODE). Furthermore, the Multiple Times Scale (MTS) method is employed to find approximate solution for the nonlinear time, frequency and forced responses of the sandwich nano-beam. Comparison between results of this paper and previous published paper shows that our numerical results are in good agreement with literature. In addition, the nonlinear frequency, force response and nonlinear damping time response is carefully studied. The influences of important parameters such as nonlocal parameter, volume fraction of the CNTs, different patterns of CNTs, length scale parameter, Visco-Pasternak foundation parameter, applied voltage, longitudinal magnetic field and temperature change are investigated on the various responses. One can conclude that frequency of FG-AV pattern is greater than other used patterns.

• 한국보건간호학회지
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• 제29권2호
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• pp.165-176
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• 2015

Purpose: This study was conducted to examine the relationships of depression symptom, self-esteem, and stress with health-related quality of life(HRQOL) in patients with hypertension registered to a community health center. Methods: This study was a correlational survey using a convenience sampling. A total of 110 patients diagnosed with hypertension were recruited from a health center in Gyeonggi-do. The questionnaires used were the Cardiovascular Disease Specific-HRQOL questionnaire, Center for Epidemiologic Studies Depression, Rosenberg Self-Esteem Scale, and Perceived Stress Scale. The acquired data were analyzed using IBM SPSS version 22.0. Multiple linear regression analysis was performed. Results: Moderate depression symptom(${\beta}=-.368$, p<.001), severe depression symptom (${\beta}=-.450$, p<.001), stress(${\beta}=-.339$, p=.001), and gender(${\beta}=-.148$, p=.049) were significant predictors for the HRQOL. Multiple linear regression showed that 51.8% ($R^2=.518$) of the variance in the HRQOL was explained. Conclusion: Based on these results, development of an intervention or education program, to decrease depression symptoms and stress is recommended. This may improve the HRQOL in patients with hypertension registered to a community health center.