• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.1333-1336
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• 2003

최근의 인터넷은 기하급수적으로 폭증하는 트래픽을 원활히 수용하기 위하여 광인터넷으로 급속히 전환되고 있다. 이에 따라 새롭게 제시되는 네트워크 구조를 기반으로 네트워크 설계 단계에서 구축단계까지 새로운 운용관리 체계를 필요로 한다. 광인터넷 시뮬레이션 도구는 이러한 요구사항을 효과적으로 지원할 수 있는 도구로서 네트워크 요소시스템의 기능성 검증 및 네트워크 운용성 검증 등을 제공할 수 있다. 한편 광인터넷 시뮬레이션 도구에 있어서 광인터넷의 표현 및 모델링은 주요한 요구사항 중의 하나이며 이는 DML(Domain Modeling Language) 기반의 네트워크 모델링 컴포넌트를 통하여 구성될 수 있다. DML 은 간단하면서 고급의 모델 정의 기능을 제공하고 인터넷과 같은 대규모 모델로의 확장이 용이하며 이종 엔진과의 시뮬레이션 모델교환 형식으로도 사용이 가능하므로, 광인터넷 시뮬레이션 도구에서 시뮬레이션 모델의 표현에 매우 적합하다. 따라서 이 논문에서는 광인터넷 시뮬레이션 도구에 적용 가능한 DML 기반 네트워크 모델링 컴포넌트를 설계한다.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.4
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• pp.360-364
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• 2011

Backlash is common in mechanical and hydraulic systems and severely limits overall system performance. In this paper, the development of an adaptive control scheme for systems with unknown backlash is presented. An adaptive backlash inverse based controller is applied to a plant that has an unknown backlash in its input. The harmful effects of backlash are presented. Compensation for backlash by adding a discrete adaptive backlash inverse structure and the gradient-type adaptive algorithm, which provides the estimated backlash parameters, are also presented. The supposed adaptive backlash control algorithms are applied to an aircraft with unknown backlash in the actuator of control surfaces. Simulation results show that the proposed compensation scheme improves the tracking performance of systems with backlash.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1411-1413
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• 2000

Distubance of air-gap sensors by rail irregularities are the serious problem deteriorating the performance in the electromagnetic suspension (EMS) systems. Thus, this paper proposes the output feedback controller with discrete kalman filter for the EMS systems. The discrete kalman filter estimate true state value and output feedback controller guarantee stability. The benefit of this scheme are shown by simulation. Therefore air-gap disturbance are rejected successfully.

• Journal of Aerospace System Engineering
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• v.9 no.4
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• pp.62-66
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• 2015

During the conceptual design of turboprop aircraft, the power effect driven from rotating propeller is typically obtained from empirical data. In the present paper, propeller power effect was obtained by using unsteady three-dimensional Navier-Stokes solver with $k-{\omega}$ turbulence model for the accurate prediction of turboprop aircraft performance. In order to simulate the relative motion between propeller and fuselage, unsteady sliding mesh method was used. During simulation, three flow conditions such as climb, cruise and descending flight were selected considering the flight envelop of the real turboprop aircraft. For the correction of aerodynamic coefficients, the thrust effect of engine exhaust gas was included based on the engine manufacturer's data. Using the computational results, the correction table for the aerodynamic coefficient of turboprop aircraft was suggested for the performance analysis of turboprop aircraft.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.147-148
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• 2007

BICC protocol is a relay protocol adaptable to ATM and IP based core networks compared to ISUP protocol to TDM networks. Using BICC protocol, multi-rate bearer traffic such as voice and video can flow in the relay core networks. BICC protocol is standardized as WCDMA circuit switching networks in 3GPP Release 4. Thus KTF is now operating core networks using BICC protocol. In this paper, we describe the background and characteristics of BICC protocol. We also provide the status of KTF WCDMA core networks using BICC. To show the efficiency of BICC protocol an analytical simulation is given in which the results can be expected by intuitive observation.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.11-20
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• 2002

This paper proposed a MPPT(Maximum Power Point Tracking) control algorithm for PV(Photovoltaic) array based on a modified constant voltage control MPPT algorithm at low insolation. This method which combined a reference voltage control and a constant voltage control algorithm. In contrast to the typical conventional MPPT algorithm, the proposed method have been obtained high efficiency and good performance in all insolation intensity. The proposed algorithm is verified through simulation and experiment.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.432-434
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• 2013

VTS에서 항해하는 선박들은 자율적인 행위자들로서 서로 영향을 끼치며 상호작용하는 한편 서로의 안전에 대해서 상호의존하게 된다. 복잡한 항해상황에서의 불확실성으로 인한 위험을 극복하기 위한 방안으로 최근에 상황자각 이론이 각광을 받고 있다. 하지만 다수의 선박들에 의한 개별적인 상황판단이 제대로 이루어진다 하더라도 동일한 상황에 대한 해석이 서로 다른 경우 사고로 이어질 우려가 높다. 본질적으로 VTS 항해는 인지 과업을 서로 도와가면서 항해하는 시스템이라고 할 수 있다. 본고에서는 팀 상황자각이 공통기반과 동일한 멘탈모델에 의해 성공적으로 이루어지는 과정을 논의하고, 상황자각 실패 사례를 통해 좀 더 구체적으로 살펴보았다. 또한 팀 상황자각과 관련하여 커뮤니케이션의 중요성을 강조하고 VTS 항해 상황에서 항해자들의 팀상황자각을 실질적으로 도울 수 있는 방법으로 '공동운용화면' 시스템을 제안하였다.

• KIEE International Transactions on Power Engineering
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• v.5A no.3
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• pp.235-243
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• 2005

Line constants of the catenary system are estimated. The harmonic current that the Korean Train Express (KTX) injects into the catenary is measured to precisely analyze the harmonic effects. The Korean high-speed railway system is modeled by estimated and measured results. The system model is applied for predicting the harmonic effects. The simulation results from the system model are compared to field test data concerning the total harmonic distortion (THD). The reliability of the system model is verified.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1060-1062
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• 1996

This paper presents a discrete adaptive observer for MIMO system of an IM model in DQ reference model. The IM model in the stationary frame is discretized and it is transformed into the canonical observer form. The unknown parameter is choosen as rotor speed. The adaptive law for parameter adjustment is obtained as a set of recursive equations which are derived by utilizing an exponentially weighted normalized least-square method. The proposed adaptive observer converges rapidly and is also shown to track time-varying plant parameter quickly. Its effectiveness has been demonstrated by computer simulation.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.280-283
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• 2000

In this paper, a fault tolerant control problem is considered for a class of nonlinear system formulated in a gain scheduling form with LMI-based H-inf control technique Key benefits of this proposed scheme are demonstrated in the simulation of an electromagnetic suspension system with actuator and/or sensor failures, and the method is compared with the convensional state-feedback and output-feedback controller. It is clearly observed that the proposed control scheme shows an improved output performance in comparision with convensional methods.