• 한국컴퓨터산업학회논문지
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• 제7권3호
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• pp.253-262
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• 2006

폐쇄된 계 내에서 발생하는 운동과 계 외에서 작용하는 힘에 의해 발생하는 운동은 뚜렷한 차이가 있다. 계 내에서 발생하는 운동에 의해 외부로 운동이 나타난 경우 닫힌 운동이고 계 외에서 원인으로 한 방향으로 발생하는 운동은 열린 운동이다. 닫힌 운동 모델은 선형 닫힌 운동계와 비선형 닫힌 운동계가 있다. 선형 닫힌 운동의 원리와 종류 및 실험 장치를 통하여 근사 수식모델을 만들고 여러 가지 비선형 닫힌 운동 모델 종류와 실험 장치를 비교하였다. 또한 비선형 닫힌 운동 모델이 조합되어 선형 닫힌 운동 모델이 될 수 있음을 알 수 있다.

• 한국소음진동공학회논문집
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• 제17권10호
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• pp.983-992
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• 2007

It was proposed to identify Thiele Small Parameters for loudspeaker attached to closed-box using known dynamic mass of moving parts. Also, enhanced PSPICE circuit model for closed-box loudspeaker system was proposed to more accurately simulate real closed-box loudspeaker system. Frequency dependent parameters were used to model voice coil inductor. Acoustic pressure response curves and electrical impedance curves were simulated and investigated by PSPICE circuit model according to compensation filter's parameters. Finally, proposed method is expected to be utilized for identification of pseudo Thiele Small parameters of microspeaker.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.864-869
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• 2004

A novel concept of feedback loop design for modal test and model updating is proposed. This method uses the closed -loop natural frequency information for parameter modification to overcome the problems associated with the conventional method employing the modal sensitivity matrix. To obtain new modal information from closed-loop system, controllers should be effective in changing modal data while guaranteeing the stability of closed-loop system. It is very hard to guarantee the stability of the closed-loop system with non-collocated sensor and actuator set. Ill this research, we proposed a controller called mode-decoupling controller that can change a target mode as much as the designer wants guaranteeing the stability of closed-loop system. This controller can be computed just using measured open-loop modeshape matrix. A simulation based on time domain input/output data is performed to check the feasibility of proposed control method.

• Structural Engineering and Mechanics
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• 제10권1호
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• pp.67-79
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• 2000

Critical loads and load-carrying capacities for steel scaffolds used as shoring systems were compared using computational and experimental methods in Part I of this paper. In that paper, a simple 2-D model was established for use in evaluating the structural behavior of scaffold-shoring systems. This 2-D model was derived using an incremental finite element analysis (FEA) of a typical complete scaffold-shoring system. Although the simplified model is only two-dimensional, it predicts the critical loads and failure modes of the complete system. The objective of this paper is to present a closed-form solution to the 2-D model. To simplify the analysis, a simpler model was first established to replace the 2-D model. Then, a closed-form solution for the critical loads and failure modes based on this simplified model were derived using a bifurcation (eigenvalue) approach to the elastic-buckling problem. In this closed-form equation, the critical loads are shown to be function of the number of stories, material properties, and section properties of the scaffolds. The critical loads and failure modes obtained from the analytical (closed-form) solution were compared with the results from the 2-D model. The comparisons show that the critical loads from the analytical solution (simplified model) closely match the results from the more complex model, and that the predicted failure modes are nearly identical.

• 한국정밀공학회지
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• 제16권12호
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• pp.78-86
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• 1999

The improvement of the water level control is important since it will prevent the steam generator trip so that improve the reliability and credibility of operation system. In this paper, the closed loop system identification is performed which can be used for the system monitoring and prediction of the system response. The model also can be used for the prediction control. Irving model is used as a steam generator model. The plant is an open loop unstable and non-minimum phase system. Fuzzy controller stabilize the system and the stable controller stabilize the system and the stable closed loop system is identified using neural networks. The obtained neural network model is validated using the untrained input and output. The results of computer simulation show the obtained Neural Network model represents the closed loop system well.

• Computers and Concrete
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• 제23권1호
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• pp.11-23
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• 2019

Nowadays, the characterization of Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) tensile behavior still remains a challenge for researchers. For this purpose, a simplified closed-form non-linear hinge model based on the Third Point Bending Test (ThirdPBT) was developed by the authors. This model has been used as the basis of a simplified inverse analysis methodology to derive the tensile material properties from load-deflection response obtained from ThirdPBT experimental tests. In this paper, a non-linear finite element model (FEM) is presented with the objective of validate the closed-form non-linear hinge model. The state determination of the closed-form model is straightforward, which facilitates further inverse analysis methodologies to derive the tensile properties of UHPFRC. The accuracy of the closed-form non-linear hinge model is validated by a robust non-linear FEM analysis and a set of 15 Third-Point Bending tests with variable depths and a constant slenderness ratio of 4.5. The numerical validation shows excellent results in terms of load-deflection response, bending curvatures and average longitudinal strains when resorting to the discrete crack approach.

• 대한지리학회지
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• 제31권4호
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• pp.648-661
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• 1996

본 연구는 기존의 튀넨 모형(또는, 생산지향 모형)의 결함을 보완하기 위한 Closed 모형의 개발과 이의 검증을 중심으로 한 연구이다. 생산지향모형의 가장 큰 결함은 시장기능을 도외시한 점이라고 할 수 있는데, 특히 시장가격의 결정 구조가 전혀 고려되지 않은 점이다. 이러한 문제을 바탕으로 생산지향 모형에서 도출된 농산물의 공급측 가격과 일반적인 수요측면에서 도출된 가격, 이 양자의 상호결합에 의해 Closed 모형이 제시 되었다. 이 모형은 시 뮤 레 이 션(simulation)에 의해 검정되고 생산지향 모형과 비교되었다. 그 결과는 첫째, 생산지향 모형에서 경작지 면적은 운송비 감소와 생산비의 절감에 Closed 모형의 결과에 비해 과도하게 증가하는 예측이 이루어진다. 둘째, Closed 모형에서는 농산물 농산물 가격이 사장기능에 의해 조절되며 변화한다는 점이 파악된다. 셋째, 특정작물의 단위당 생산량의 증가는 생산지향 모형에서는 그 작물의 공간적인 확대로 연결되고 시장가격은 불변인데 비해 Closed 모형에서는 반드시 그러한 공간확대로 이어지지는 않고, 수요가 일정한 상태일 때는 오히려 경작지 면적이 줄 수 있다고 예상된다. 이와 같은 성격을 갖고 있는 Closed 모형이, 불확실한 환경조건에서 농작물 상호간의 경쟁하에 경작지면적, 작물의 총생산량, 및 시장가격의 결정을 이해하기위해서 응용되었다. 본 연구에서는 우선 생산지향 모형을 바탕으로, 다양한 기후변화에 따른 토지이용의 변화를 경쟁입찰지대(bid-rent) 수식에 의해 파악해보았다. 그 결과는 어떤 특정한 기후에서 다른 작물보다 열등인 작물은 쉽게 공간에서 배제되는 점에 비해, Closed 모형에서는 비록 기후조건이 나쁜 환경에 처한 작물이라도 그 작물에 대한 수요가 있을 경우에는 계속적으로 경작이 된다는 결과를 보인다. 반면에 기후조건이 유리한 작물은 생산량의 증대로 시장가격은 하락되고, 일정한 수요상태에서는 경작지면적의 감소로 이어지는 결과가 예측된다.

• 한국소음진동공학회논문집
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• 제14권10호
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• pp.955-961
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• 2004

A novel concept of feedback loop design for modal test and model updating is proposed. This method uses the closed-loop natural frequency information for parameter modification to overcome the problems associated with the conventional method employing the modal sensitivity matrix. To obtain new modal information from closed-loop system, controllers should be effective in changing modal data while guaranteeing the stability of closed-loop system. But it is very hard to guarantee the stability of the closed-loop system with non-collocated sensor and actuator set. In this research, we proposed a controller called mode-decoupling controller that can change a target mode as much as the designer wants guaranteeing the stability of closed-loop system. This controller can be computed Just using measured open-loop modeshape matrix. A simulation based on time domain input/output data is performed to check the feasibility of proposed control method.

• 한국컴퓨터산업학회논문지
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• 제8권3호
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• pp.181-186
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• 2007

폐쇄된 계 내부와 외부에서 작용되는 운동에는 선형 열린 운동과 닫힌 운동이 있고 비선형 열린 운동과 닫힌 운동이 있다. 선형 닫힌 운동이 마찰과 같은 외력을 받을시 갇힌 운동이 발생된다. 회전 닫힌 운동에도 마찰과 같은 외력을 받을시 회전 갇힌 운동이 있음을 해석 한다. 회전 닫힌 운동과 갇힌 운동을 액체 실험 장치를 통하여 정량적으로 고찰하고 회전 갇힌 운동이 있음을 분석하여 회전 열린 운동, 닫힌 운동 과 갇힌 운동에 대한 컴퓨터 씨뮬레이션 수식모델을 정한다. 그리고 간단한 운동 장치의 그래픽 구조를 고려 할 수 있도록 소개한다.

• Structural Engineering and Mechanics
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• 제38권2호
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• pp.157-169
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• 2011

In this paper the time-dependent closed-form static solution of the suspended pre-stressed biconcave and biconvex cable trusses with unmovable, movable and elastic or viscoelastic yielding supports subjected to various types of vertical load is presented. Irvine's forms of the deflections and the cable equations are modified because the effects of the rheological behaviour needed to be incorporated in them. The concrete cable equations in the form of the explicit relations are derived and presented. From a solution of a vertical equilibrium equation for a loaded cable truss with rheological properties, the additional vertical deflection as a time-function is determined. The time-dependent closed-form model serves to determine the time-dependent response, i.e., horizontal components of cable forces and deflection of the cable truss due to applied loading at the investigated time considering effects of elastic deformations, creep strains, temperature changes and elastic supports. Results obtained by the present closed-form solution are compared with those obtained by FEM. The derived time-dependent closed-form computational model is used for a time-dependent simulation-based reliability assessment of cable trusses as is described in the second part of this paper.