• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.42-43
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• 2022

Marine AtoN에 대한 정보 수집 및 트렌드 분석을 위하여 IALA에서는 2~4년 주기로 설문조사를 수행하고 있다. 이는 전 세계의 AtoN에 대한 통계정보를 수집하고 제공하기 위한 강력한 도구이나, 응답률이 매우 저조하여 유의미한 데이터 분석이 불가능한 상황이다. 또한, ARM 15차 회의에서 IALA 설문 체계의 문제점이 제기되며, IALA 설문체계 개선에 대한 필요성과 IALA 회원국의 AtoN data 수집 및 관리에 대한 필요성이 대두되고 있다. 이러한 데이터 수집·관리 요구에 대응하기 위하여 본 연구에서는 IALA 설문체계의 문제점 분석 후, 단계적인 개선 방안을 제시하였다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.477-483
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• 1999

This paper presents a design of deadbeat control system for DC motor driving such a rotational mechanical system with gear as a printing machine. The deadbeat response design developed for control system of a sampled continuous-data process does not guarantee zero intersampling ripples, but the proposed deadbeat control system that consists of the integral controller and the full-order state observer, has many advantages such as an output response without the ripples, and setting time than the optimal control system in the same sampling period. The results of case study through MATLAB simulation are shown that the efficiency of the proposed controller for DC motor driving a rotational system with gear is verified by comparing with optimal controller etc..

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.109-115
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• 2008

This paper proposes an adaptive Dynamic Matrix Control (DMC) and its application to boiler-turbine system In a conventional DMC, object system is described as a Step Response Model (SRM). However, a nonlinear system is not effectively described as a single SRM. In this paper, nine SRMs at various operating points are prepared. On-line interpolation is performed at every sampling step to find the suitable SRM. Therefore, the proposed adaptive DMC can consider the nonlinearity of boiler-turbine system. The simulation results show satisfactory results with a wide range operation of the boiler-turbine system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.281-288
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• 2014

As a gas explosion is the most fatal accident in shipbuilding and offshore plant industries, all safety critical elements on the topside of offshore platforms should retain their integrity against blast pressure. Even though many efforts have been devoted to develop blast-resistant design methods in the offshore engineering field, there still remain several issues needed to be carefully investigated. From a procedure for calculation of explosion design pressure, impulse of a design pressure model having completely positive side only is determined by the absolute area of each obtained transient pressure response through the CFD analysis. The negative pressure phase in a general gas explosion, however, is often quite considerable unlike gaseous detonation or TNT explosion. The main objective of this study is to thoroughly examine the effect of the negative pressure phase on structural behavior. A blast wall for specific FPSO topside is selected to analyze structural response under the blast pressure. Because the blast wall is considered an essential structure for blast-resistant design. Pressure time history data were obtained by explosion simulations using FLACS, and the nonlinear transient finite element analyses were performed using LS-DYNA.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.3
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• pp.163-171
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• 2024

Structural health monitoring for ships and offshore structures is important in various aspects. Ships and offshore structures are continuously exposed to various environmental conditions, such as waves, wind, and currents. In the event of an accident, immense economic losses, environmental pollution, and safety problems can occur, so it is necessary to detect structural damage or defects early. In this study, structural response data of multi-linked floating offshore structures under various wave load conditions was calculated by performing fluid-structure coupled analysis. Furthermore, the order reduction method with distortion base mode was applied to the structures for predicting the structural response by using the results of numerical analysis. The distortion base mode order reduction method can predict the structural response of a desired area with high accuracy, but prediction performance is affected by sensor arrangement. Optimization based on a genetic algorithm was performed to search for optimal sensor arrangement and improve the prediction performance of the distortion base mode-based reduced-order model. Consequently, a sensor arrangement that predicted the structural response with an error of about 84.0% less than the initial sensor arrangement was derived based on the root mean squared error, which is a prediction performance evaluation index. The computational cost was reduced by about 8 times compared to evaluating the prediction performance of reduced-order models for a total of 43,758 sensor arrangement combinations. and the expected performance was overturned to approximately 84.0% based on sensor placement, including the largest square root error.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.3
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• pp.334-341
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• 2003

In this paper, we proposed a recurrent time delayed neural network(RTDNN) controller which compensate a output of neural network controller. Even if learn by neural network controller, it can occur an bad results from disturbance or load variations. So in order to adjust above case, we used the fuzzy compensator to get an expected results. And the weight of main neural network can be changed with the result of learning a inverse model neural network of plant, so a expected dynamic characteristics of plant can be got. As the results of simulation through the second order plant, we confirmed that the proposed recurrent time delayed neural network controller get a good response compare with a time delayed neural network(TDU) controller. We implemented the controller using the DSP processor and applied in a hydraulic servo system. And then we observed an experimental results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.263-270
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• 2021

In this study, a reliability-based design optimization of a 130-m class fixed-type offshore platform, to be installed in the North Sea, was carried out, while considering environmental, material, and manufacturing uncertainties to enhance its structural safety and economic aspects. For the reliability analysis, and reliability-based design optimization of the structural integrity, unity check values (defined as the ratio between working and allowable stress, for axial, bending, and shear stresses), of the members of the offshore platform were considered as constraints. Weight of the supporting jacket structure was minimized to reduce the manufacturing cost of the offshore platform. Statistical characteristics of uncertainties were defined based on observed and measured data references. Reliability analysis and reliability-based design optimization of a jacket-type offshore structure were computationally burdensome due to the large number of members; therefore, we suggested a method for variable screening, based on the importance of their output responses, to reduce the dimension of the problem. Furthermore, a deterministic design optimization was carried out prior to the reliability-based design optimization, to improve overall computational efficiency. Finally, the optimal design obtained was compared with the conventional rule-based offshore platform design in terms of safety and cost.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.253-255
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• 2013

수요가 늘어가고 있는 부유식 해양플랜트 구조물의 열악한 해양환경에서의 구조물의 노후화, 사고발생 가능성에 대비해 지속적인 평가가 필요하나, 기존의 구조물에 사용되는 안전성 평가 기법으로는 한계가 있어, 상시적인 구조물의 건전성 평가기법이 필요하다. 그래서 본 연구에서는 상시적인 구조물의 건전성 평가기법을 위해 부유식 구조물의 상시적인 응답 가속도를 추출하여 해당 구조물의 동적특성을 추출 하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.259-264
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• 1997

본 논문에서는 Westinghouse(WH)사에서 공급한 고리 3, 4호기의 증기발생기 모델에 강인제어 기법의 하나인 QFT(Quantitative Feedback Theory)를 적용하여 플랜트에 존재하는 불확실성이나 외란에 대해 강인성을 보장하는 제어기를 설계하였다. 증기발생기의 주파수응답 한계조건은 MATLAB QFT Toolbox를 이용하였으며, loop shaping에 의한 전달함수 식별을 위해서 근사화 기법을 적용하였다. 그리고 5∼20[%]의 저출력구간에서 모의실험을 하여 본 논문의 유용성을 보였다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.379-383
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• 1998

본 논문에서는 플랜트를 제어하는데 있어 광범위하게 사용되는 PD제어기의 파라미터를 결정하는 문제에 대한 연구를 하였다. 파라미터 결정 방법으로는 최근 최적화 문제에 많이 적용되고 있는 새로운 방법인 유전자 알고리즘을 사용하였다. 또한 이렇게 정해진 파라미터를 사용하여 이를 도립진자(Inverted Pendulum)에 적용하였고 도립진자의 응답특성을 분석, 고찰함으로써 PD제어기의 성능을 평가.확인하고 이 문제에 적용된 유전자 알고리즘의 우수성을 입증하였다.