• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.945-949
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• 2010

In this paper, a systematic design of a new robust nonlinear variable structure controller based on state dependent nonlinear form is presented for the control of uncertain affine nonlinear systems with mismatched uncertainties and matched disturbance. After an affine uncertain nonlinear system is represented in the form of state dependent nonlinear system, a systematic design of a new robust nonlinear variable structure controller is presented. To be linear in the closed loop resultant dynamics, the linear sliding surface is applied. A corresponding control input is proposed to satisfy the closed loop exponential stability and the existence condition of the sliding mode on the linear sliding surface, which will be investigated in Theorem 1. Through a design example and simulation study, the usefulness of the proposed controller is verified.

• Smart Structures and Systems
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• v.11 no.6
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• pp.569-587
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• 2013

This paper evaluates the closed loop performance of the reaching law based discrete sliding mode controller with multisensor data fusion (MSDF) in real time, by controlling the first two vibrating modes of a piezo actuated structure. The vibration is measured using two homogeneous piezo sensors. The states estimated from sensors output are fused. Four fusion algorithms are considered, whose output is used to control the structural vibration. The controller is designed using a model identified through linear Recursive Least Square (RLS) method, based on ARX model. Improved vibration suppression is achieved with fused data as compared to single sensor. The experimental evaluation of the closed loop performance of sliding mode controller with data fusion applied to piezo actuated structure is the contribution in this work.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1295-1301
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• 2010

In this note, a systematic general design of a new robust nonlinear variable structure controller based on state dependent nonlinear form is presented for the control of uncertain affine nonlinear systems with mismatched uncertainties and mismatched disturbance. After an affine uncertain nonlinear system is represented in the form of state dependent nonlinear system, a systematic design of a new robust nonlinear variable structure controller is presented. To be linear in the closed loop resultant dynamics, the nonlinear integral-type sliding surface is applied. A corresponding control input is proposed to satisfy the closed loop exponential stability and the existence condition of the sliding mode on the nonlinear integral-type sliding surface, which will be investigated in Theorem 1. Through a design example and simulation studies, the usefulness of the proposed controller is verified.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.688-694
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• 2021

The aim of this work is the analysis, design and hardware implementation of the fractional-order point kinetics (FNPK) model along with its closed-loop controller. The stability and closed-loop control of FNPK models are critical issues. The closed-loop stability of the controller-plant structure is established. Further, the designed PI/PD controllers are implemented in real-time on a DSP processor. The simulation and real-time hardware studies confirm that the designed PI/PD controllers result in a damped stable closed-loop response.

• Steel and Composite Structures
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• v.45 no.5
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• pp.715-728
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• 2022

Closed steel supports of different shapes are used in mining and underground constructions. The supports are prefabricated from rolled, usually robust, steel profiles. The load carrying capacity of a support is considerably influenced by the active loading and passive forces. The passive forces are induced by interactions between the support and the surrounding rock mass. The analysis herein comprises three parts: The first part consists of structural geometry processing. The second part involves finding the numerical solution of a statically indeterminate structure for a specified load. The third part is calculation of the load carrying capacity and the components of internal forces and deformations. For this, the force method and numerical integration are used. The Winkler model is applied when the support interacts with the surrounding environment. The load carrying capacity is limited by the slip resistance of the connected parts and it is limited by reaching the ultimate state of the profile. This paper serves as a comprehensive reference for the determination of the load carrying capacity of closed steel supports and includes stepwise derivations of the governing formulas.

• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.383-388
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• 2007

In this paper, we propose a new signal frame structure based on Alamouti code that can maintain the same performance as Alamouti code and increase spectral efficiency. The proposed signal frame structure can increase spectrum efficiency to approach 1(bit/s/Hz) since it can process n bit data during (n+1) time slot. In order to verify two performances, we derive closed form BER via mathematical approach, and compare with the simulation result in Rayleigh fading plus AWGN channel. Then we find that the two performances are exactly same.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.130-139
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• 2004

The Casing Oscillator is a bore file Equipment for the all-casing process. All-casing process is a method of foundation work in construction yard to oscillate steel Casing in the ground. The existing Casing Oscillator has some problem like not boring horizontally with disturbance and not driving Casing othor angle except horizon. To solve problem, the new structure Casing Oscillator is presented and studied. The performance of Casing Oscillator is improved by kinematics analysis. The Casing Oscillator is similar to the parallel manipulator in structure. So we obtain Inverse kinematics solution of Casing Oscillator easily. But it is difficult to solve forward kinematics of Casing Oscillator. T his paper presents a novel pose description corresponding to the structure characteristics of parallel manipulators. Through analysis on geometry theory, we obtain a new method of the closed-form solution to the forward kinematics using Kinematic Inversion. The closed-form solution contains two different meanings -analytical and real-time. So we reach the goal of practical application and control. Closed-form forward kinematics solution is verified by an inverse kinematics analysis. It shows that the method has a practical value for real -time control and inverse kinematics servo control.

• Asia pacific journal of information systems
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• v.29 no.3
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• pp.382-406
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• 2019

We study the antecedents to tie formation on an (Facebook-like) enterprise social media platform implemented to support cross-boundary connections. Research has produced mixed findings regarding the role of social media in cultivating bridging vs. closed networks. We examine the tie formation patterns of 1,386 enterprise social media users over a two-year period. Specifically, we observe who became (or chose not s become) "friends" with whom at the dyadic level and relate the decisions to various mechanisms that affect one's network to expand, constrain, or bridge. Using logistic and OLS regressions, we find that users tend to form ties via reciprocity and transitivity (with friends of friends), both of which help expand one's network. We also find strong networking tendency toward functional and hierarchical homophily (same business unit and same rank, respectively), which is likely to constrain one's network (closed network structure). We find that one's participation in various online interest groups is likely to open one's network (bridging network structure) while no evidence found for preferential attachment. Overall, we find that enterprise social media offers features, some of which are likely to foster bridging while others foster closed networks via different mechanisms.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.281-293
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• 2008

In the layered medium, the Sommerfeld integral must be evaluated to calculate a space domain Green's function. The real axis integration method provides stable and accurate results over wide ranges of the observation distance and the singnal frequency. But this method has the in efficiency of approximation when the field point z is changed. Also, as the amplitude of z increases, the change of the spectral domain function is more rapidly. Therefore, the approximation is difficult when z becomes larger. In this paper, we propose a method to calculate an accurate closed-form Green's function for microstrip structure by using the closed-loop integration path.

• Journal of the Korean Institute of Educational Facilities
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• v.27 no.3
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• pp.25-31
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• 2020

The reasons for studying the case of Japan are as follows. First, the increases in the aged population is similar to the case of Korea, and consumers are aging as the population ages. Second, the structure of industry in Japan is very similar to Korea, which describes the fact that the share of the manufacturing industry decreases but the service industry (e.g., medicine, finance, and insurance) increases. Third, Japan is considered as the best predictive model for forecasting the future of closed schools in Korea because the GNI gross income per capita is relatively close to the one of Korea among the several neighboring countries. The purpose of this study is to analyze the current extent of utilizing closed schools in Japan and, based on the analysis, to provide basic data on the use of closed schools in Korea in the future. The types of closed schools can be classified into education facilities, social welfare facilities, cultural facilities, public sports facilities, income growing facilities, and others. Based on the classification, the analyses of the characteristics of each type for the facilities are presented. and When the utilization status of closed schools in Japan is analyzed, 363 schools were utilized (51.4%) in 2003, means the lowest utilization rate of the target year, after that 4198 schools (70.6%) were utilized in 2015. The utilization ratio is steady increased.