• 한국지능시스템학회논문지
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• 제13권6호
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• pp.729-736
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• 2003

In this paper, we propose that the chaotic behavior analysis in the mobile robot of embedding some chaotic such as Chua`s equation, Arnold equation with obstacle. In order to analysis of chaotic behavior in the mobile robot, we apply not only qualitative analysis such as time-series, embedding phase plane, but also quantitative analysis such as Lyapunov exponent In the mobile robot with obstacle. We consider that there are two type of obstacle, one is fixed obstacle and the other is VDP obstacle which have an unstable limit cycle. In the VDP obstacles case, we only assume that all obstacles in the chaos trajectory surface in which robot workspace has an unstable limit cycle with Van der Pol equation.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
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• pp.123-127
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• 2004

In this paper, we propose that the chaotic behavior analysis in the several Arnold chaos mobile robot of embedding some chaotic such as Arnold equation with obstacle. In order to analysis of chaotic behavior in the mobile robot, we apply not only qualitative analysis such as time-series, embedding phase plane, but also quantitative analysis such as Lyapunov exponent in the mobile robot with obstacle. We consider that there are two type of obstacle, one is fixed obstacle and the other is hidden obstacle which have an unstable limit cycle. In the hidden obstacles case, we only assume that all obstacles in the chaos trajectory surface in which robot workspace has an unstable limit cycle with Van der Pol equation.

• 대한인간공학회지
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• 제16권3호
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• pp.71-75
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• 1997

This paper presents the development of videobased 3-dimensional tracking system. Measurement of human motion is important in the application of ertonomics. The system uses advanced direct video measurement technology. Passive retro-reflecting markers are attached to a subject and movements of markers are observed by two CCD cameras. Infrared light emitted near the CCD cameras is reflected by the markers and is detected by the cameras. The images are captured by Samsung MVB302 board and the centers of markers are calculated by DSP program. The positions of markers are transferred from MVB02 board to the computer through AT bus. The computer then tracks the position of each marker and saves the data. This system has dynamic accuracy with 0.7% average error and 4.2% maximum error, and the sampling rate to 6 .approx. 10 Hz, and this system can analyse the trajectory and speed of the marker. The results of this study can be used for operator's motion analysis, task analysis, and hand movement characteristic analysis.

• Wind and Structures
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• 제13권2호
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• pp.191-206
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• 2010

Windborne debris is a major cause of structural damage during severe windstorms and hurricanes owing to its direct impact on building envelopes as well as to the 'chain reaction' failure mechanism it induces by interacting with wind pressure damage. Estimation of debris risk is an important component in evaluating wind damage risk to residential developments. A debris risk model developed by the authors enables one to analytically aggregate damage threats to a building from different types of debris originating from neighboring buildings. This model is extended herein to a general debris risk analysis methodology that is then incorporated into a vulnerability model accounting for the temporal evolution of the interaction between pressure damage and debris damage during storm passage. The current paper (Part I) introduces the debris risk analysis methodology, establishing the mathematical modeling framework. Stochastic models are proposed to estimate the probability distributions of debris trajectory parameters used in the method. It is shown that model statistics can be estimated from available information from wind-tunnel experiments and post-damage surveys. The incorporation of the methodology into vulnerability modeling is described in Part II.

• 한국철도학회논문집
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• 제2권1호
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• pp.38-46
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• 1999

This study proposes the analysis and evaluation method of time series ultrasonic signal using the attractor analysis. Features extracted from time series signal analyze quantitatively characteristics of weld defects. For this purpose, analysis objective in this study is fractal dimension and attractor quadrant feature. Trajectory changes in the attractor indicated a substantial difference in fractal characteristics resulting from distance shifts such as parts of head and flange even though the types of defects are identified. These differences in characteristics of weld defects enables the evaluation of unique characteristics of defects in the weld zone. In quantitative fractal feature extraction, feature values of 3.848 in the case of part of head(crack) and 4.102 in the case of part of web(side hole) and 3.711 in the case of part of flange(crack) were proposed on the basis of fractal dimensions. Proposed attractor feature extraction in this study can enhance the precision rate of ultrasonic evaluation for defect signals of rail weld zone such as side hole and crack.

• Journal of Welding and Joining
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• 제18권5호
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• pp.77-83
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• 2000

This study proposes the analysis and evaluation method of time series ultrasonic signal using the attractor analysis. Features extracted from time series signal analyze quantitatively characteristics of weld defects. For this purpose, analysis objective in this study is fractal dimension and attractor quadrant feature. Trajectory changes in the attractor indicated a substantial difference in fractal characteristics resulting from distance shifts such as parts of head and flange even though the types of defects are identified. These difference in characteristics of weld defects enables the evaluation of unique characteristics of defects in the weld zone. In quantitative fractal feature extraction, feature values of 3.848 in the case of part of head(crack) and 4.102 in the case of part of web(side hole) and 3.711 in the case of part of flange(crack) were proposed on the basis of fractal dimensions. Proposed attractor analysis and DAC in this study can enhance the precision rate of ultrasonic evaluation for defect signals of rail weld zone such as side hole and crack.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.404-408
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• 2005

Having flexibility in a manipulator will degrade trajectory tracking control and manipulator tip positioning. In practice, however, constraints imposed by various operating requirements, will render the presence of such flexibility unavoidable. The dynamic analysis of the flexible manipulator is essential in designing proper control systems. A flexible manipulator consists of infinite number of elastic modes and the modes are usually coupled to each other. For the practicality, however, it is usually assumed that the flexible system consists of finite number of elastic modes and the modes are decoupled. These assumptions result in a linear and decoupled mathematical model of the flexible manipulator and simplify the analysis of the dynamic behavior and the design of the control system. The decoupling and linearization of the flexible link, however, has been assumed without in depth analysis. This paper focuses on the analysis of the significance of the non-linear coupling factors.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.87-95
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• 1998

This study proposes the analysis and evaluation method of time series ultrasonic signal using the attractor analysis. Features extracted from time series signal analyze quantitatively characteristics of welding defects. For this purpose, analysis objective in this study is fractal dimension and attractor Quadrant feature. Trajectory changes in the attractor indicated that even the same type of defects carried substantial difference in fractal characteristics resulting from distance shifts such as parts of head and flange. Such differences in characteristics of weld defects enables the evaluation of unique features of defects in the weld zone. In quantitative fractal feature extraction, feature values of 3.848 in the case of part of head(crack) and 4.102 in the case of part of web(side hale) and 3.711 in the case of part of flange(crack) were proposed on the basis of fractal dimensions. Proposed attractor feature extraction in this study can enhance the precision rate of ultrasonic evalaution for defect signals of rail weld zone such as side hole and crack.

• 대한토목학회논문집
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• 제7권1호
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• pp.11-22
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• 1987

흐름수역(水域)에서 연직상향으로 방류되는 평면부력(平面浮力)?의 거동이 연속방정식(連續方程式), 운동량방정식(運動量方程式) 및 추적물수송식(追跡物輸送式)의 기본방정식을 수치적(數値的)으로 풀음으로서 해석(解析)된다. 난류확산(亂流擴散)에는 Prandtl의 혼합거리이론(混合距離理論)을 도입한 난류수송모형(亂流輸送模型)이 이용된다. 수치해과정(數値解過程)은 기본방정식을 유함수(流凾數)(stream function)식(式)과 골도수송(滑度輸送)(vorticity transport)식을(式) 이용하여 변환(變換)한 후, ?방류속도(放流速度), ?방류구폭(放流口幅) 등(等)으로 표현되는 변수(變數)와 흐름을 지배(支配)하는 무차원매개변수(無次元媒介變數)를 도입하여 무차원화(無次元化)하고 successive under-relaxation을 이용하여 Gauss-Seidal 반복법(反復法)으로 해를(解) 구(求)하는 것이다. 수치실험(數値實驗)은 방류(放流)Froude수(數)가 4~32, 방류속도(放流速度)와 가로흐름속도와의 비로(比) 정의되는 속도비가 8~15 의 범위의 흐름영역(領域)에서 수행되었다. 부력(浮力)?으로 인한 주변(周邊)흐름수역(水域)의 속도변화(速度變化), 온도상승(溫度上昇)범위, 흐름상태 및 골도(滑度)가 조사되었으며, ?의 경로에 대한 속도비와 방류밀도Froude 수의 영향이 또한 조사되었다. ?중심선의 속도, 온도변화, 국부밀도(局部密度)Froude 수(數)의 변화가 계산되며 퍼짐율(spreading rate)과 확산비(擴散比)(dispersion ratio)가 방류밀도(放流密度)Froude 수, 국부밀도(局部密度)Froude 수(數) 및 속도비(速度比)의 항(項)으로 해석되었다. 또한 속도와 온도분포를 상사(相似)(similarity)로 나타낼 수 있음이 밝혀졌으며, Gaussian 분포(分布)를 이용한 적분형해석(積分型解析)(integral type analysis)이 가능한 것으로 사료된다.

• 한국융합학회논문지
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• 제10권7호
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• pp.243-249
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• 2019

본 연구는 중 고령자의 사회참여 변화를 유형화 하고 각 변화에 대한 결정요인을 탐색하는 데 목적이 있다. 분석자료는 한국 고령화연구패널조사 1차(2006)부터 6차(2016)년까지의 자료를 활용하였고, 분석 대상은 패널조사의 응답자 중 남성 1,327명, 여성 1,520명인 총 2,847명이었다. SPSS 22.0, M-plus 8.0 통계 프로그램을 통해 성장혼합 모형을 실시한 결과, 중 고령자의 사회참여 변화는 '고수준 감소형', '중수준 증가형', '저수준 유지형'으로 유형화 되었다. 각 유형에 대한 결정요인을 분석한 결과, 교육수준이 높을수록 저수준 유지형보다 고수준 감소형과 중수준 증가형에 속할 확률이 높으며, 도시지역에 거주할수록 저수준 유지형보다 고수준 감소형에 속할 가능성이 높은 것으로 확인되었다. 또한 직업이 없을수록 저수준 유지형보다 중수준 증가형에 속할 확률이 높은 것으로 확인되었다. 이러한 분석 결과를 통해 중 고령자 사회참여 촉진에 관한 함의점을 논의하였다.