• The Korean Journal of Ecology
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• 제23권2호
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• pp.113-116
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• 2000

Different phenological patterns of leaf and fruit fall among native and non-native riparian species provide a spatially and temporally heterogeneous series of alternative food resources for detritivores. Relatively little is known about qualitative differences among these different riparian species. Rates of litter inputs, decomposition, and retention for different sources of riparian litter require long-term documentation. Species of freshwater shrimps, crabs. insects. and gastropods are known to consume a wide range of litter inputs but how these dynamic food webs function under changing climatic and land-use conditions is unknown, especially in tropical streams. On-going studies in the Luquillo Experimental Forest. Puerto Rico provide an example of how inputs of fronds and fruits from palms (Prestoea montana) serve as important foods and microhabitat for species of freshwater crabs and shrimp. Native riparian species such as Prestoea montana are commonly distributed in the Luquillo Mountains especially along steep slopes and stream banks. After tropical storms with high winds, the large fronds from these native riparian trees provide important inputs of leaf litter to the stream food web. In some streams, the input of ripe fruit from non-native trees such as Java plum (Syzigium jambos) also provides a major source of detrital food resources, especially during periods when fruit fall from native species of palms may be limited.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.781-785
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• 1989

In the field of control technology, too, it is about time that the students should free themseleves from the paradigm of Newtonian mechanics. Otherwise, they might fail to grasp the essence of control. Now, let us consider the essence of control. Control consists of manipulating a particular object, matter, energy of environment on the basis of certain medium information. (measurement data, force, etc.) So, we shall look into the methods of manipulation. Here, we consider natural control, constraining control, and hybrid control as basic methods of manipulation. In this paper, we would like to put forward the daring proposal that it's called a Holon-type hybrid control system. It is intended to control a plat with complicated or unknown characteristics where a conventional control theory is not easy to apply. A prototype system has been developed and applied to a real plant. The control system is a multi-layer system. Each layer includes different control input. The important features of the system are as follows: 1) Each layer behaves autonomously and also cooperates with each other to optimize the whole plant. 2) The controller optimizes a plant without mathematical models when these models are not easy to obtain.

• 전자공학회논문지B
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• 제32B권5호
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• pp.747-755
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• 1995

When codebooks designed by a clustering algorithm using training sets, a time-averaged distortion, which is called the inside-training-set- distortion (ITSD), is usually calculated in each iteration of the algorithm, since the input probability function is unknown in general. The algorithm stops if the ITSD no more significantly decreases. Then, in order to test the trained codebook, the outside-training-set-distortion (OTSD) is to be calculated by a time-averaged approximation using the test set. Hence codebooks that yield small values of the OTSD are regarded as good codebooks. In other words, the calculation of the OTSD is a criterion to testing a trained codebook. But, such an argument is not always true if some conditions are not satisfied. Moreover, in order to obtain an approximation of the OTSD using the test set, it is known that a large test set is requared in general. But, large test set causes heavy calculation com0plexity. In this paper, from the analyses in [16], it has been revealed that the enough size of the test set is only the same as that of the codebook when codebook size is large. Then a simple method to testing trained codebooks is addressed. Experimental results on synthetic data and real images supporting the analysis are also provided and discussed.

• 전자공학회논문지SC
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• 제38권6호
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• pp.28-36
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• 2001

피드-포워드 보상부분과 불연속 제어 부분으로 구성되는 강건한 적응 슬라이딩 모드 로봇제어 알고리즘을 유도하였다. 미지의 매개변수는 실시간으로 추정되는 매개변수를 포함하는 그룹과 실시간으로 추정하지 않는 매개변수를 포함하는 그룹으로 나누어진다. 그런 다음 외란 및 실시간으로 추정하지 않는 매개변수에서의 불확실성 효과를 보상하기 위해 슬라이딩 제어 항이 토크 입력에 포함된다. 또한 매니퓨레이터 동역학 구조의 효율적인 이용으로 인하여 알고리즘은 계산이 간단하다. 매개변수 불확실성과 외부 외란의 존재에도 불구하고 제어기는 대국적 점근적으로 안정하며 추적오차가 영에 수렴함을 보여준다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.663-668
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• 1990

This paper deals with the application of a Generalized Predictive Control (CPC) to a Pressurized Water Reactor (P.W.R) Nuclear Power Plant. Generalized Predictive Control is a sort of Explicit Self-Tuning Control. Current self-tuning algorithms lack robustness to prior choices of either dead-time (input time delay of a plant) or model order. GPC is shown by simulation studies to be superior to accepted self-tuning techniques such as minimum variance and pole-placement from the viewpoint that it is robust to prior choices of dead-time or model order. In this paper a GPC controller is designed to control the P.W.R. nuclear power rlant with varying dead-time and through the designing procedure the designer is free from the constraint of knowing the exact dead-time. The controller is constructed based on the 2nd order linear model approximated in the vicinity of operating point. To ensure that this low-order model describes the complex real dynamics well enough for control purposes, model parameters are updated on-line with a Recursive Least Squares algorithm. Simulation results are successful and show the possibilities of the GPC control application to actual plants with varying or unknown dead-time.

• 제어로봇시스템학회논문지
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• 제21권1호
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• pp.34-39
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• 2015

In this paper, a finite impulse response (FIR) filter is proposed for discrete-time nonlinear systems. The proposed filter is designed by combining the estimate of the perturbation state and nominal state. The perturbation state is estimated by adapting the optimal time-varying FIR filter for the linearized perturbation model and the nominal state is directly obtained from the nonlinear nominal trajectory model. Since the FIR structured estimators use the finite horizon information on the most recent time interval, the proposed extended FIR filter satisfies the bounded input/bounded output (BIBO) stability, which can't be obtained from infinite impulse response (IIR) estimators. Thus, it can be expected that the proposed extended FIR filter is more robust than IIR structured estimators such as an extended Kalman filter for the round-of errors and the uncertainties from unknown initial states and uncertain system model parameters. The simulation results show that the proposed filter has better performance than the extended Kalman filter (EKF) in both robustness and fast convergency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1959-1960
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• 2008

The Logic Built In Self Test (LBIST) technique is substantially applied in chip design in most many semiconductor company in despite of unavoidable overhead like an increase in dimension and time delay occurred as it used. Currently common LBIST software uses the MISR (Multiple Input Shift Register) However, it has many considerations like defining the X-value (Unknown Value), length and number of Scan Chain, Scan Chain and so on for analysis of result occurred in the process. So, to solve these problems, common LBIST software provides the solution method automated. Nevertheless, these problems haven't been solved automatically by Tri-state Bus in logic circuit yet. This paper studies the algorithm that it also suggest algorithm that reduce additional circuits and time delay as matching of pattern about 2-type circuits which are CUT(circuit Under Test) and additional circuits so that the designer can detect the wrong location in CUT: Circuit Under Test.

• 융합신호처리학회논문지
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• 제14권3호
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• pp.169-180
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• 2013

The modification of conditional Fuzzy C-Means (CFCM) with Gaussian weights (CFCM_GW) is accomplished for blind equalization of channels in this paper. The proposed CFCM_GW can deal with both of linear and nonlinear channels, because it searches for the optimal desired states of an unknown channel in a direct manner, which is not dependent on the type of channel structure. In the search procedure of CFCM_GW, the Bayesian likelihood fitness function, the Gaussian weighted partition matrix and the conditional constraint are exploited. Especially, in contrast to the common Euclidean distance in conventional Fuzzy C-Means(FCM), the Gaussian weighted partition matrix and the conditional constraint in the proposed CFCM_GW make it more robust to the heavy noise communication environment. The selected channel states by CFCM_GW are always close to the optimal set of a channel even when the additive white Gaussian noise (AWGN) is heavily corrupted. These given channel states are utilized as the input of the Bayesian equalizer to reconstruct transmitted symbols. The simulation studies demonstrate that the performance of the proposed method is relatively superior to those of the existing conventional FCM based approaches in terms of accuracy and speed.

• 한국지능시스템학회논문지
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• 제7권3호
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• pp.21-33
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• 1997

본 논문에서는 바람직한 제어 방향의 학습을 통한 퍼지 제어기의 새로운 자기 구성 방법을 제안한다. 기울기 강하법에 기반하여 특성을 모르는 동적 플랜트에 대한 퍼지 제어기를 자기 구성할 때 풀어야할 문제중 하나는 오차를 줄이도록 하는 바람직한 제어입력의 변화방향을 알아내는 것이다. 이 문제를 해결하기 위한 방법으로서, 제어입력에 따른 오차의 변화 방향에 대한 대표 값을 분할된 상태영역에 할당하고, 반복적인 시행을 통해 강화 학습된 이 대표값을 이용하여 퍼지 제어 규칙을 학습하는 방법을 제안하였다. 제안된 자기구성 퍼지제어기는 간단한 구조를 가질 뿐 아니라 설계하기도 쉬운 장점을 갖는다. 제안된 방법의 타당성은 역진자 시스템에 대한 모의 실험을 통하여 검증하였다.

• 한국항공운항학회지
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• 제14권4호
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• pp.38-47
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• 2006

This study analyzes the expense structure of the air transport industry, based on the cost and income data of 18 major airlines, estimates the economic effectiveness of scale and conducts comparative analysis. As for the method of analysis, Translog cost function and the Fourier flexible function were used. The result showed that big companies had the economy of scale based on the Translog cost function, while the Fourier flexible function led to a estimation that expanding the input is not recommended, for the expansion of scale entails the poor economy of scale. It can be presumed that the economy of scale was estimated according to the U shape of the Translog cost function in the given data. On the other hand, the Fourier flexible cost function approaches the unknown function, as it is a Fourier series, and correctly infers the economy of scale based on the analyzed data. As for the flag carrier's economy of scale, it was inferred that the economy of scale existed by any of two functions. Therefore, the conclusion was that further expanding the scale will not cause any problem.