• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2003년도 춘계종합학술대회논문집
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• pp.403-405
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• 2003

학부생들이 쉽게 사용할 수 있는 기법인 반복 그린함수 방법(IGFM)을 이용하여 복잡한 전자파 도파관 구조를 이론적으로 해석한다. IGFM은 그린함수와 반복법을 이용한다. IGFM의 간단한 공식화를 위해 단순한 수학 방정식만을 사용한 물리적인 메커니즘을 이용한다. 전형적인 전자파 도파관 구조인 평행판 E평면 T접합에 대한 산란 특성을 IGFM 관점에서 이론적으로 공식화한다. 수치해석 결과를 주파수에 대한 반사와 투과 전력 관점에서 보인다. 우세모드 해를 유도하고 그 결과를 고차모드에 의한 해와 비교한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.643-645
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• 1999

In experiment, a real inverted pendulum system has state constraints and limited amplitude of input. These problems make it difficult to design a swing-up controller. To overcome these problems, we design a sliding mode controller considering physical behaviour of the inverted pendulum system. This sliding mode controller uses a switching control action to converge along a specified path derived from energy equation from a state around the path to desired states(standing position). And optimal control method is used to guarantee stability at unstable equilibrium position. The designed controller can be applied to all inverted pendulum systems regardless of the values of their parameters. Compared with previous existing controllers, it is simple and easy to tune. Experimental results are given to show the effectiveness of this controller.

• 대한조선학회 특별논문집
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• 대한조선학회 2017년도 특별논문집
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• pp.19-27
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• 2017

In spite of adoption of Intact Stability Code Part A as mandatory, the accidents have been occurred frequently caused by dynamic stability. Therefore International Maritime Organization (IMO) is revising the Intact Stability Code to prevent the cause of accidents. The result of 4th meeting of Sub-committee on Ship Design and Construction (SDC), five mode of the cause was defined and establishing each draft regulations. We consider physical background, mathematical description, draft regulations for five failure mode and sample calculations for ships built by STX Offshore & Shipbuilding.

• 한국음향학회지
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• 제7권4호
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• pp.110-116
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• 1988

한국 남서 해안에 겨울철 발생하는 수온전선으로 매우 특이한 음향매체가 존재한다. 이러한 조건하에서의 음파방정식은 변수분리가 용이하고 그 해 역시 간단하며 이는 이미 잘 알려진 수학적인 해이다. 수평 성분의 방정식 해를 구하기 위하여 WKB 방법 대신 mode 방법을 사용하였으며 구한 해의 특성은 수온전선이 존재함으로 야기된 수중음속의 수평변화로 인한 영향은 주파수에 따라 그 크기가 달라진다. 이를 설명하기 위해 ray tracing 을 이용, 그 물리적인 의미를 부여하였다.

• Steel and Composite Structures
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• 제16권6호
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• pp.595-609
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• 2014

The paper is reporting some comparisons between experimental and numerical results in terms of failure mode, failure time and ballistic properties of mild steel sheet. Several projectile shapes have been considered to take into account the stress triaxiality effect on the failure mode during impact, penetration and perforation. The initial and residual velocities as well as the failure time have been measured during the tests to estimate more physical quantities. It has to be noticed that the failure time was defined using a High Speed Camera (HSC). Thanks to it, the impact forces (average and maximum level), were analyzed using numerical simulations together with an analytical description coupled to experimental observations. The key point of the model is the consideration of a shape function to define the pulse loading during perforation.

• 한국정밀공학회지
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• 제26권4호
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• pp.64-71
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• 2009

A 3-D rehabilitation robot system is developed in this paper. The robot system is for the rehabilitation of upper extremities, especially the shoulder and elbow joints, and has 3-D workspace for enabling occupational therapy to recover physical functions in activities of daily living(ADL). The rehabilitation robot system, which is driven by actuators, has 1 DOF in horizontal rotational motion and 2 DOF in vertical rotational motion, where all actuators are set on the ground. Parallelogram linkage mechanisms lower the equivalent inertia of the control elements as well as control forces. Also the mechanisms have high mechanical rigidity for the end effector and the handle. Passive motion mode experiments have been performed to evaluate the proposed robot system. The results of the experiments show and excellent performance in simulating spasticity of patients.

• KSTLE International Journal
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• 제1권1호
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• pp.29-33
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• 2000

In this study, a methodology is developed and confirmed to find the physical contact between the slider and disc due to the defects of disk during head seeking operation using acoustic emission (AE) signal. The head/disk contact was detected during random and standard seeks, whereas no contact was detected during track fellowing. During standard and random seeks, the torsion mode of slider excitation was observed at 680KHz. Therefore, it is thought that AE technique can be used as an alternative method of the glide test by monitoring existence of the torsional mode of the slider during seek operation or can be used to detect the spacing loss during seeking operation. By appropriately choosing the location of the sensor an order of magnitude increase in the sensitivity for RMS AE signal is observed. Therefore we can find take-off velocity clearly with high signal to noise ratio of AE signal.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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• pp.447-452
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• 1998

A fault is considered as a variation of physical parameters; therefore the design of fault detection and identification(FDI) can be reduced to the parameter identification of a non linear system and to the association of the set of the estimated parameters with the mode of faults. ANFIS(Adaptive Neuro-Fuzzy Inference System) which contains multiple linear models as consequent part is used to model non linear systems. In this paper, we proposes an FDI system for non linear systems using ANFIS. The proposed diagnositc system consists of two ANFISs which operate in two different modes (parallel-and series-parallel mode). It generates the parameter residuals associated with each modes of faults which can be further processed by additional RBF (Radial Basis function) network to identify the faults. The proposed FDI scheme has been tested by simultation on a two-tank system

• 소음진동
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• 제9권2호
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• pp.273-284
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• 1999

The cylindrical shells are used as primary components of complex structures such as airplane fuselages and nuclear pressure vessels. Recently the free vibration analysis of these structures are investigated by many researchers. The engineering informations on experimental validation of the free vibration behavior on the simply supported cylindrical shells are very few. The experimental methods for realizing the physical boundary condition of simply supported edges are examined. Natural frequencies and mode shapes of the isotropic and plain weave composite simply supported shells are obtained by modal tests. A theoretical and finite element analysis are also performed in order to validate the experimental results. The experimental results indicate that the simply supported boundary conditions with bolts along the circumferential direction of shell in both ends are well achieved. Those are shown to agree with the analytical results and with the finite element analysis results. These methods can be used to realize other experimental simple support boundary conditions.

• Structural Engineering and Mechanics
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• 제78권1호
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• pp.1-13
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• 2021

In this study, the porothermoelastic problem with the effect of the magnetic field and initial stress was investigated. We applied normal mode analysis to solve the resulting non-dimensional coupled equations. Numerical results for the displacements, temperature distribution, pore pressure, stresses, induced electric field and induced magnetic field distributions are presented graphically and discussed. The medium deformed because of thermal shock and due to the application of the magnetic field, there result an induced magnetic and an induced electric field in the medium. Numerical analyses are given graphically on the square (2D) and cubic (3D) domains to illustrate the effects of the porosity parameter, magnetic field and initial stress parameter on the physical variables.