• 제어로봇시스템학회논문지
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• 제12권4호
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• pp.380-388
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• 2006

A noisy behavior of the time domain passivity controller during the period of low velocity is analyzed. Main reasons of the noisy behavior are investigated through a simulation with a one-DOF (Degree of Freedom) haptic interface model. It is shown that the PO/PC is ineffective in dissipating the produced energy when the sign of the velocity, which is numerically calculated from the measured position, is suddenly changed, and when this velocity is zero. These cases happen during the period of low velocity due to the limited resolution of the position sensor. New methods, ignoring the produced energy from the velocity sign change, and holding the control force while the velocity is zero, are proposed for removing the noisy behavior. The feasibility of the developed methods is proved with both a simulation and a real experiment.

• 한국전자통신학회논문지
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• 제7권4호
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• pp.855-859
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• 2012

본 연구에서는 선형시변 발진기 위상잡음 이론에 있어서 전력 스펙트럼 밀도식의 일반화된 형태를 유도한다. 유도된 전력 스펙트럼 밀도식을 바탕으로 선형시변 발진기 위상잡음 이론은 발진 신호의 전력 보존성을 예측할 수 있음을 본 연구에서 증명한다. 게다가, 유도된 전력 스펙트럼 밀도식은 선형시변 발진기 위상잡음 이론이 기본 주파수와 그 하모닉을 포함하는 전 주파수 영역에 걸친 전력 스펙트럼의 특성을 설명 할 수 있게 한다.

• 한국산업융합학회 논문집
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• 제17권2호
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• pp.42-53
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• 2014

Robust voice recognition (RVR) is essential for a robot to communicate with people. One of the main problems with RVR for robots is that robots inevitably real environment noises. The noise is captured with strong power by the microphones, because the noise sources are closed to the microphones. The signal-to-noise ratio of input voice becomes quite low. However, it is possible to estimate the noise by using information on the robot's own motions and postures, because a type of motion/gesture produces almost the same pattern of noise every time it is performed. In this paper, we propose an RVR system which can robustly recognize voice by adults and children in noisy environments. We evaluate the RVR system in a communication robot placed in a real noisy environment. Voice is captured using a wireless microphone. Navigation Strategy is shown Obstacle detection and local map, Design of Goal-seeking Behavior and Avoidance Behavior, Fuzzy Decision Maker and Lower level controller. The final hypothesis is selected based on posterior probability. We then select the task in the motion task library. In the motion control, we also integrate the obstacle avoidance control using ultrasonic sensors. Those are powerful for detecting obstacle with simple algorithm.

• 대한가정학회지
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• 제27권1호
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• pp.85-96
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• 1989

The purpose of study was to survey the indoor noise of apartment houses, residents, attitudes and their adaptation behavior in order to offer the information helpful to apartment designers and residents, in their housing policy. Documentary research and questionnaire survey methods were used in this research. The sample was taken from 187 housewives living in apartments in Seoul. Data were analyzed with the SPSS program. The results were as follow : 1. It was found that apartment residents pointed out washing machine noise inside the home, piano and other musical instruments noise outside the home. 2. Piano and other musical instrument noise were heard at 3 to 6 pp.m. when residents heard the noise, and water supply and drainage noise in bathrooms were found most noisy. 3. Apartment residents were discontent with noise outside the home, and they displayed positive adaptation behavior at a reduced noise level. 4. Attitudes arising from indoor noise in apartment houses and human noise, water supply and drainage noise, doorway opening and closing noise were found to be significant in sampled apartment groups. 5. The youngest child's age was a significant variable on the residents' attitudes and adaptation behavior of indoor noise in apartment houses. 6. Between the resident' attitudes and adaptation behavior involving indoor noise in apartment houses. 6. Between the resident' attitueds and adaptation behavior involving indoor noise apartment houses, the more they became discontented, the more quickly they adapted in a postive manner.

• Communications for Statistical Applications and Methods
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• 제4권2호
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• pp.453-463
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• 1997

Nonparametric kernel regression has recently gained widespread acceptance as an attractive method for the nonparametric estimation of the mean function from noisy regression data. Also, the practical implementation of kernel method is enhanced by the availability of reliable rule for automatic selection of the bandwidth. In this article, we propose a method for automatic selection of the bandwidth that minimizes the asymptotic mean square error. Then, the estimated bandwidth by the proposed method is compared with the theoretical optimal bandwidth and a bandwidth by plug-in method. Simulation study is performed and shows satisfactory behavior of the proposed method.

• 한국시뮬레이션학회논문지
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• 제28권4호
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• pp.21-32
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• 2019

군집에 대한 사회적 행동 모델에 영감을 받은 군집 최적화 알고리즘은 복잡한 최적화 문제 해결에서부터 인공 신경망의 학습에까지 활용되는 대표적인 메타휴리스틱 최적화 알고리즘 중의 하나이다. 하지만 이 알고리즘은 기본적으로 확률적 노이즈가 존재하지 않는 결정적인 환경에서 개발되었기 때문에, 많은 경우 확률적 노이즈가 존재하는 실제 문제에 적용하기에 어려움이 있었다. 본 논문에서는 이를 개선하기 위하여 불확실 평가 기법이라고 정의되는 통계적 가설 검정 기반의 리샘플링 기법을 적용한다. 이 기법을 통하여 입자 군집 최적화 알고리즘의 성능에 가장 큰 영향을 미치는 입자들의 전역 최적을 정확하게 찾으므로 노이즈 환경에서 입자들이 최적해로 보다 정확하고 빠르게 수렴하도록 한다. 다양한 벤치마크 문제들에 대한 기존 알고리즘들과의 비교 실험 결과는 제안하는 알고리즘의 개선된 성능을 입증하고, 사례 연구의 결과는 본 연구의 필요성을 강조한다. 본 연구 결과가 4차 산업혁명 시대에 디지털 트윈 등을 통한 시뮬레이션 기반 시스템 최적화에 효과적으로 적용될 수 있을 것이라 기대한다.

• International Journal of Control, Automation, and Systems
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• 제4권5호
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• pp.624-636
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• 2006

This paper proposes a hybrid approach involving Genetic Algorithm (GA) and Bacterial Foraging (BF) for tuning the PID controller of an AVR. Recently the social foraging behavior of E. coli bacteria has been used to solve optimization problems. We first illustrate the proposed method using four test functions and the performance of the algorithm is studied with an emphasis on mutation, crossover, variation of step sizes, chemotactic steps, and the life time of the bacteria. Further, the proposed algorithm is used for tuning the PID controller of an AVR. Simulation results are very encouraging and this approach provides us a novel hybrid model based on foraging behavior with a possible new connection between evolutionary forces in social foraging and distributed non-gradient optimization algorithm design for global optimization over noisy surfaces.

• 대한기계학회논문집A
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• 제29권2호
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• pp.277-283
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• 2005

Kriging model is widely used as design analysis and computer experiment (DACE) model in the field of engineering design to accomplish computationally feasible design optimization. In general, kriging model has been applied to many engineering applications as an interpolation model because it is usually constructed from deterministic simulation responses. However, when the responses include not only global nonlinearity but also numerical error, it is not suitable to use Kriging model that can distort global behavior. In this research, generalized kriging model that can represent both interpolation and regression is proposed. The performances of generalized kriging model are compared with those of interpolating kriging model for numerical function with error of normal distribution type and trigonometric function type. As an application of the proposed approach, the response of a simple dynamic model with numerical integration error is predicted based on sampling data. It is verified that the generalized kriging model can predict a noisy response without distortion of its global behavior. In addition, the influences of maximum likelihood estimation to prediction performance are discussed for the dynamic model.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.638-642
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• 2001

본 논문에서는 국부적인 미디안(median)규칙에 따라 움직이는 셀룰러 오토마타를 이용해 화상에 대한 사전 지식이 필요 없는 화상의 잡음제거 알고리즘을 제안한다. 각 규칙은 원화상이 가지는 특징의 손실없이 국부적으로 밝기값(gray level)을 증감시킨다. 이러한 셀룰러 오토마타는 순차적이고 병렬적인 움직임을 가지며, 이 움직임은 Lyapunov functional을 만족하는 함수로 표현된다. 따라서 본 셀룰러 오토마타를 이용한 화상의 잡음제거 알고리즘은 매우 빠른 속도로 수렴하고, 안정적인 결과를 나타낸다. 실험을 통해 본 방법의 유효성을 확인한다.

• 한국정보통신학회논문지
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• 제5권2호
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• pp.343-348
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• 2001

본 논문에서는 국부적인 미디안(median)규칙에 파라 움직이는 셀룰러 오토마타를 이용해 영상에 대한 사전 지식이 필요 없는 영상의 잡음제거 알고리즘을 제안한다. 각 규칙은 원영상이 가지는 특징의 손실없이 국부적으로 자기값(gray level)을 증감시킨다. 이러한 셀룰러 오토마타는 순차적이고 병렬적인 움직임을 가지며, 이 움직임은 Lyapunov functional을 만족하는 함수로 표현된다. 따라서 본 셀룰러 오토마타를 이용한 영상의 잡음제거 알고리즘은 매우 빠른 속도로 수렴하고, 안정적인 결과를 나타낸다. 실험을 통해 본 방법의 유효성을 확인한다.