• 전기학회논문지
• /
• 제58권1호
• /
• pp.173-180
• /
• 2009

It is difficult to predict non-stationary or chaotic time series which includes the drift and/or the non-linearity as well as uncertainty. To solve it, we propose an effective prediction method which adopts data preprocessing and multiple model TS fuzzy predictors combined with model selection mechanism. In data preprocessing procedure, the candidates of the optimal difference interval are determined based on the correlation analysis, and corresponding difference data sets are generated in order to use them as predictor input instead of the original ones because the difference data can stabilize the statistical characteristics of those time series and better reveals their implicit properties. Then, TS fuzzy predictors are constructed for multiple model bank, where k-means clustering algorithm is used for fuzzy partition of input space, and the least squares method is applied to parameter identification of fuzzy rules. Among the predictors in the model bank, the one which best minimizes the performance index is selected, and it is used for prediction thereafter. Finally, the error compensation procedure based on correlation analysis is added to improve the prediction accuracy. Some computer simulations are performed to verify the effectiveness of the proposed method.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
• /
• 제11권3호
• /
• pp.61-73
• /
• 2005

Recently, Korea is becoming a world-leading country in various industrial fields with it's advanced information technology. In the 20th century, Korea went through a chaotic period from Japanese colonization via the Korean war to IMF because of lack of globalization. Now, we have a mission and the abilities to lead world-wide trends in entire fields of society. This study, comparing the modern healthcare planning trends in Korea, China, Japan and the United States, proposes the Northeast Asia Healthcare Network Plan which Korea leads. United States is the starter of healthcare network, but it's location is too far from Asia and IT is also inferior to the Korean. Japan seems to have no concerns with this healthcare network. And the current China is a rapid growing period and is too much for building its domestic healthcare infra-structure. they still have no concerns with re-structuring of healthcare system and facilities. Because of these reasons, I think Korea should have to lead Northeast Asia Healthcare network.

• 산업공학
• /
• 제18권3호
• /
• pp.221-233
• /
• 2005

e-Manufacturing can be referred to as a system methodology enabling the integration of manufacturing operations and IT technologies to achieve objectives of an enterprise. It is recently regarded as a powerful solution to survive in a chaotic marketplace. While conducting an e-Manufacturing project, we first needed to capture collaborative processes conducted by multiple participants in order to define functions of a system supporting them. However, pervasive process modeling techniques including IDEF3, Petri nets, and UML are not sufficient for modeling collaborative processes. Therefore, we first briefly investigate several process modeling methods including aforementioned modeling methods and ARIS focusing on the collaboration point of view. Then, we propose a new modeling method referred to as Collaborative Process Modeling (CPM) to clearly describe collaborative processes. Also, we develop and illustrate a rule for transforming collaborative process models into Marked Graph models to use the analysis power of the Petri nets. Using CPM empowers us to develop collaborative process models with simple notations, understand and facilitate the realization of the collaboration, and verify models before rushing into the development.

• Ocean Systems Engineering
• /
• 제8권3호
• /
• pp.345-360
• /
• 2018

Increasing demand for large-sized Floating, Storage and Regasification Units (FSRUs) for oil and gas industries led to the development of novel geometric form of Buoyant Leg Storage and Regasification Platform (BLSRP). Six buoyant legs support the deck and are placed symmetric with respect to wave direction. Circular deck is connected to buoyant legs using hinged joints, which restrain transfer of rotation from the legs to deck and vice-versa. Buoyant legs are connected to seabed using taut-moored system with high initial pretension, enabling rigid body motion in vertical plane. Encountered environmental loads induce dynamic tether tension variations, which in turn affect stability of the platform. Postulated failure cases, created by placing eccentric loads at different locations resulted in dynamic tether tension variation; chaotic nature of tension variation is also observed in few cases. A detailed numerical analysis is carried out for BLSRP using Mathieu equation of stability. Increase in the magnitude of eccentric load and its position influences fatigue life of tethers significantly. Fatigue life decreases with the increase in the amplitude of tension variation in tethers. Very low fatigue life of tethers under Mathieu instability proves the severity of instability.

• 대한기계학회논문집A
• /
• 제30권2호
• /
• pp.194-201
• /
• 2006

Gait analysis is essential to identify accurate cause and knee condition from patients who display abnormal walking. Traditional linear tools can, however, mask the true structure of motor variability, since biomechanical data from a few strides during the gait have limitation to understanding the system. Therefore, it is necessary to propose a more precise dynamic method. The chaos analysis, a nonlinear technique, focuses on understand how variations in the gait pattern change over time. Eight healthy eight subjects walked on a treadmill for 100 seconds at 60 Hz. Three dimensional walking kinematic data were obtained using two cameras and KWON3D motion analyzer. The largest Lyapunov exponent from the measured knee angular displacement time series was calculated to quantify local stability. This study quantified the variability present in time series generated from gait parameter via chaos analysis. Knee flexion-extension patterns were found to be chaotic. The proposed Lyapunov exponent can be used in rehabilitation and diagnosis of recoverable patients.

• 한국콘텐츠학회논문지
• /
• 제6권2호
• /
• pp.34-43
• /
• 2006

본 논문은 가변적 비디오 트랙을 위한 모델링 방법을 제시한다. 가변적인 비디오 트랙은 간헐적인 버스트 및 긴 구간 상관관계의 특성을 갖는다고 잘 알려져 있다. 이러한 데이터를 분석하기 위해서, 에러 임계값으로부터 구한 보조적인 선형 구조를 갖는 신경망 구조 모델 구축을 한다. 모델링 결과 테스트를 위해서, 흔돈 비선형 함수와 지수 랜덤 노이즈를 결합한 가변적 비디오 트랙을 발생하였다. 발생된 데이터를 모델링한 결과, 전통적인 신경망 모델에 비해서 제시된 모델이 보다 정확한 모델링 결과를 보여 주었다. 그러나 또한 제시된 모델에 ARは을 결합한 결과가 제시된 모델 단독인 경우에 비해서 더욱 발생된 데이터의 통계적 특성에 근접함을 발견했다.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2007년도 추계종합학술대회
• /
• pp.336-339
• /
• 2007

카오스 신호는 공학, 의학 그리고 생물학과 같은 모든 분야에서 많이 이용되고 있으며 최근 카오스 신호를 이용한 디지털 통신시스템에 대한 연구도 활발히 이루어지고 있다. 본 논문은 카오스 신호를 디지털 통신시스템에 적용할 목적으로 System Generator를 이용하여 비선형 방정식으로 구성된 6개의 카오스 신호 발생기를 설계하고 FPGA로 하드웨어를 구현하였다. 이 결과로부터 Hardware co-simulation으로 본 설계를 검증하기 위해 비트 스트림을 FPGA 보드로 로드하였다. 또한 6개의 카오스 발생기의 성능을 평가하기 위해 타이밍 해석을 통한 최대 동작 주파수와 사용한 로직의 resource량을 조사하여 비교하였다.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 1997년도 한국감성과학회 연차학술대회논문집
• /
• pp.69-74
• /
• 1997

Sleep deprivation may affect the brain functions such as cognition and, consequentoy, dynamics of the EEG. we examiced the effects of sleep deprivation on chaoticity of EEG. Five volunteers were sleep-deprived over a period of 24 hours, They were checked by EEG during two days, the first day of baseline period, EEGs were reorded form 16 channels for nonlinear analysis. We dmployed a method of minimum cmbedding dimension to calculate the first positive Lyapunov exponent. For limited noisy data, this algorithm was strikingly faster and more accurate than previous ones. Our results show that the sleep deprived volunteers had lower values of the first positive Lyapunov exponent at ten channels (Fp$\_$1/, F$\_$4/, F$\_$8/, T$\_$4/, T$\_$5/, C$\_$3/, C$\_$4/, P$\_$3/, p$\_$4, O$\_$1/) compared with the values of baseline periods. These results suggested that sleep deprivation leads to decreawe of chaotic activity in brain and impairment of the information processing in the brain. We suggested that nonlinear analysis of the EEG before and after sleep deprivation may offer fruitful perspectives for understanding the role o f sleep deprivation on the brain function.

• 한국식생활문화학회지
• /
• 제27권5호
• /
• pp.422-433
• /
• 2012

The purpose of this study was to investigate changes in Korean meat consumption as well as meat consumption trends. During the Japanese occupation period, the supply of meat was considerably insufficient. However, meat consumption mainly in large cities has gradually increased. Especially, 'Pyeongyang cow', a specialty of Pyeongyang, started being raised as edible beef cattle in 1933. During the chaotic period following liberation from Japan, the price of meat sharply increased. However, as the meat supply stabilized, the 'beef grade system' was introduced in 1967. Since then, beef has sold according to region. During the early economic growth period of the mid-1970s, meat consumption rapidly increased, and foreign beef was first imported in 1976. The preference for beef was somewhat attenuated due to the outbreak of mad cow disease and economic slowdown of the 1990s, resulting in an increase in the consumption of pork, a replacement meat. During the recent period of economic development, meat consumption has somewhat fallen and remained low. In late 2003, with the occurrence of mad cow disease in the US, the demand for pork, and especially pork fatback, has sharply increased.

• International Journal of Automotive Technology
• /
• 제2권1호
• /
• pp.17-23
• /
• 2001

Measurements of the initial values lead to an inverse and mathematically unprecisely formulated problem. A precise definition of an inverse problem is possible. It is to state a mathematical model of a physical process with clearly defined initial and exit values for the system behind the process. One can grasp the idea of an inverse problem by considering the tire as a copy of the objects of nature in a room with observations. Interpretation of nature is generally a result of an inverse problem. On one hand, the tire may be represented through the sensory organs and the nervous system as well as the experiences of the developer's existing apparatus of the projection of reality. On the other hand, it may be represented by a physical law or a model that can be confirmed or is to be refuted with the help of suitable measurements. During reconstruction of a measuring signal and the identification of a black box that can be assumed to be linear and causal, the tire becomes a first type Volterra integral equation of the convolution type. But measurements of the initial values are always fuzzy, the errors grow and the system behavior can no longer be forecasted. Thus, we have to deal with a chaotic system. This chaos produces fractals in a natural way. These are self-similar geometric structures. This self-similarity is clearly visible in the design.