• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.861-864
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• 2000

This paper aims to establish fundamentals of measuring and evaluating the performance of water-marking systems. We first present the general model of a watermarking method for still images. Based on this model, we propose a statistical method of measuring the performance and robustness of the watermarking system. Then, the DCT-based watermarking system is analyzed and its performance is evaluated by using the proposed method.

• 제어로봇시스템학회논문지
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• 제6권2호
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• pp.146-154
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• 2000

An $H\infty$ controller is designed for active suspensions of vehicles using 7-degree-of-freedom full-car model. Its performance robustness as well as stability robustness to system parameter variations and unmodelled dynamics are assured through the $\mu$-framework. The performance of the $H\infty$ controller is compared with that of a LQC controller in compute simulations. From the simulations it is found that the active suspension with the $H\infty$ controller reduces the acceleration and motion of the sprung mass in the heaving rolling and pitching directions when the car is driven on a normal road or through an asymmetric bump. The suspension stroke and the road holding capability are also improved with a relatively small level of power consumption. Overall the $H\infty$ controller shows a more robust performance than that of the LQG design.

• 전기학회논문지
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• 제66권6호
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• pp.927-934
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• 2017

This paper is concerned with applicability of two-degree-of-freedom controllers to the recently suggested i-PID controllers, in which unknown parts of the plant are taken into account without any modeling procedure. First, i-PID controller with two-degree-of-freedom is applied to a specific model, called Anisochronic model, to confirm the usefulness of this method. Second, using the original examples of i-PID controllers, it is confirmed that performance/robustness of system are to be improved due to two-degree-of-freedom, especially when the input changes suddenly. It is seen that as the desired robustness increases the optimal value of two-degree-of-freedom parameter ${\alpha}_A$ would be negative. It is checked and verified that if this value was limited to 1 or less as is generally known, performance would be degraded.

• 대한기계학회논문집A
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• 제27권7호
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• pp.1234-1242
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• 2003

In this paper we present a simple and efficient robust optimal design formulation for MEMS structures and its application to a resonant-type micro probe. The basic idea is to use the gradient index (GI) to improve robustness of the objective and constraint functions. In the robust optimal design procedure, a deterministic optimization for performance of MEMS structures is followed by design sensitivity analysis with respect to uncertainties such as fabrication errors and change of operating conditions. During the process of deterministic optimization and sensitivity analysis, dominant performance and uncertain variables are identified to define GI. The GI is incorporated as a term of objective and constraint functions in the robust optimal design formulation to make both performance and robustness improved. While most previous approaches for robust optimal design require statistical information on design variations, the proposed GI based method needs no such information and therefore is cost-effective and easily applicable to early design stages. For the micro probe example, robust optimums are obtained to satisfy the targets for the measurement sensitivity and they are compared in terms of robustness and production yield with the deterministic optimums through the Monte Carlo simulation. This method, although shown for MEMS structures, may as well be easily applied to conventional mechanical structures where information on uncertainties is lacking but robustness is highly important.

• 제어로봇시스템학회논문지
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• 제8권8호
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• pp.655-664
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• 2002

The disturbance observer (DOB) has been widely utilized for high precision/speed motion control applications. However, it still lacks the analysis for the robustness and performance brought by using DOB. This paper proposes the robustness measure of DOB and reveals the relationships between the disturbance rejection performance and the order/time constant of a Q filter in DOB. Additionally, we propose six guidelines for the design of Q filter and show their validity through the experiments for DVD systems.

• Structural Engineering and Mechanics
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• 제76권2호
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• pp.193-205
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• 2020

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result, risk-informed decision-making methodologies are increasingly being used as a direct decision tool or as an upper-level layer from which performance-based approaches are then calibrated against. One of the most important and challenging aspects of today's structural design is to adequately handle the system-level effects, the known unknowns and the unknown unknowns. These aspects revolve around assessing and evaluating relevant damage scenarios, namely those involving unacceptable/intolerable damage levels. Hence, the importance of risk analysis of disproportionate collapse, and along with it of robustness. However, the way robustness has been used in modern design codes varies substantially, from simple provisions of prescriptive rules to complex risk analysis of the disproportionate collapse. As a result, implementing design for robustness is still very much a grey area and more so when it comes to defining means to quantify robustness. This paper revisits the most common robustness frameworks, highlighting their merits and limitations, and identifies one among them which is very promising as a way forward to solve the still open challenges.

• 한국멀티미디어학회논문지
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• 제9권5호
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• pp.576-584
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• 2006

내용기반 비디오 정합은 원본의 클립에서 특징(signature)을 구한 후 복사본의 특징과 비교하여 유사도를 측정한다. 특히 정확한 위치의 프레임을 정합하는 것은 매우 중요하며 원본과 복사본의 프레임율, 잡음, 해상도, 압축형식에 따라 정합 율이 달라질 수 있다. 비디오 특징 중 오디널(ordinal) 특징은 일반적으로 우수한 정합특징을 나타내고 있으나 비디오 특징의 구별 능력을 나타내는 유일성 실험(uniqueness test)과 잡음에 대한 내성을 나타내는 강건성 실험(robustness test)이 중요한 요소로 고려되지 않았다. Hua등은 유일성 실험에서 해상도, 압축형식 등을 고려하였지만 강건성 실험에서 영상에 잡음을 첨가하는 대신 압축 형식이 변환된 영상을 사용하였다. 본 논문에서는 오디널 특정의 유일성 분석과 함께 실질적인 잡음 모텔을 도입하여 오디널 특징의 강건성 실험 방법을 제안하고 성능을 분석하였다.

• 조명전기설비학회논문지
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• 제19권1호
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• pp.52-58
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• 2005

제어이론들 중에 PID제어는 지난 수십년간 잘 활용되고 있다. PID 알고리즘은 PID 파라미터를 선택하기 위해서 사용되는 튜닝법이 필요하다. 그러나 어떤 경우에는 잘 알려진 튜닝법 대신에 제어기, 출력특성 및 외란제거 성능 등이 어떤 사양을 만족하도록 다양한 종류의 평가지표들을 사용하기도 하기도 한다. 본 논문에서는 오차신호, 시간, 제어입력 및 견실성을 사용한 성능지표의 선형조합을 사용하여 공조시스템의 PID제어를 한다. 성능지표를 최소화하는 2 자유도 PID파라미터를 사용하여 제어기, 출력특성 및 견실성을 분석한다. Simulink를 포함한 MATLAB을 이용하여 시뮬레이션을 한다.

• 제어로봇시스템학회논문지
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• 제9권3호
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• pp.177-185
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• 2003

Current issues of receding horizon control scheme are reviewed. The basic idea of receding horizon control is presented first. For unconstrained and constrained systems, the results of closed-loop stability in receding horizon control are surveyed. We investigate the two categories of robustness of receding horizon control : stability robustness and performance robustness. The existing optimization algorithm to solve receding horizon control problem is briefly mentioned. It is shown that receding horizon control has been extended to nonlinear systems without losing good properties such as stability and robustness. Many industrial applications are reported along with extensive references related to receding horizon control.

• 전기전자학회논문지
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• 제24권3호
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• pp.743-753
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• 2020

본 논문에서는 실감형 360도 영상의 특징점 기술의 강인성 지표를 제안한다. 이동통신사의 5G 서비스가 본격적으로 서비스됨에 따라 언제 어디서든지 대용량의 실감형 360도 영상저작물을 빠른 속도로 이용할 수 있게 되었다. 그러나 DRM 해체 및 각종 영상 변형을 통해 웹하드, 토렌트 등에서 불법 유통되고 있어 저작권 보호를 위한 강인성이 지원되는 필터링 기술이 요구되고 있다. 본 논문에서는 기존 2D 영상의 강인성 지표를 응용하고 실감형 360도 영상저작물의 특징인 투영방법 및 재생 방법을 고려한 강인성 지표를 제안하였다. 본 제안을 샘플 필터링 시스템에 대하여 적용하여 성능평가를 실시하였고 약 3초대의 실행시간에서 95% 이상의 우수한 인식률을 확인하였다.