• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권5호
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• pp.1131-1145
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• 2013

Energy detection is a widely used method for spectrum sensing in cognitive radios due to its simplicity and accuracy. However, it is severely affected by the noise uncertainty. To solve this problem, a blind multiband spectrum sensing scheme which is robust to noise uncertainty is proposed in this paper. The proposed scheme performs spectrum sensing over the total frequency channels simultaneously rather than a single channel each time. To improve the detection performance, the proposal jointly utilizes the likelihood function combined with Gerschgorin radii of unitary transformed covariance matrix. Unlike the conventional sensing methods, our scheme does not need any prior knowledge of noise power or PU signals, and thus is suitable for blind spectrum sensing. In addition, no subjective decision threshold setting is required in our scheme, making it robust to noise uncertainty. Finally, numerical results based on the probability of detection and false alarm versus SNR or the number of samples are presented to validate the performance of the proposed scheme.

• 전기학회논문지
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• 제67권2호
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• pp.314-324
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• 2018

This paper proposes a linear distributed target tracking filter for multiple unmanned aerial vehicles(UAVs) sharing their passive sensor measurements through communication channels. Different from the conventional nonlinear filtering schemes, the distributed passive target tracking problem is newly formulated within the framework of a linear robust state estimation theory incorporated with a linear uncertain measurement equation including the coordinate transform uncertainty. To effectively cope with the performance degradation due to the coordinate transform uncertainty, a linear consistent robust Kalman filter(CRKF) theory is devised and applied for designing a distributed passive target tracking filter. Through the simulations for typical UAV surveillance mission, the superior performance of the proposed method over the existing schemes of distributed passive target tracking are demonstrated.

• 기본간호학회지
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• 제6권3호
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• pp.559-569
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• 1999

The purpose of this study is to identify the effects of the supportive nursing care for arthritis patients enrolled in a rheumatoid clinic. To achieve this purpose, this study adopted a quasi-experimental, pre- and post-test research design, categorized subjects into experimental and control groups. Outpatient clinic nurse alloted the subjects by experimental and control groups and nurse researcher meets the experimental subject with in-depth, direct personal interview and advices via telephone for 8 weeks. During this pre and after the treatment period, the level of pain, uncertainty, self-efficacy, family support, and perception for health were measured. Analyses for the measured results for pre- and post-test showed that the supportive program conducted during this study decreased the level of uncertainty and increased the perception of family support in experimental group. So, the supportive healing interpersonal communication service proved to be effective and this result justifies the argument that the role of the nursing professionals at out-patient clinic should be extended for the more qualified care for the patient.

• International Journal of Contents
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• 제10권1호
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• pp.18-22
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• 2014

Hidden nodes have a key role in the information processing of feed-forward neural networks in which inputs are processed through a series of weighted sums and nonlinear activation functions. In order to understand the role of hidden nodes, we must analyze the effect of the nonlinear activation functions on the weighted sums to hidden nodes. In this paper, we focus on the effect of nonlinear functions in a viewpoint of information theory. Under the assumption that the nonlinear activation function can be approximated piece-wise linearly, we prove that the entropy of weighted sums to hidden nodes decreases after piece-wise linear functions. Therefore, we argue that the nonlinear activation function decreases the uncertainty among hidden nodes. Furthermore, the more the hidden nodes are saturated, the more the entropy of hidden nodes decreases. Based on this result, we can say that, after successful training of feed-forward neural networks, hidden nodes tend not to be in linear regions but to be in saturated regions of activation function with the effect of uncertainty reduction.

• Toxicological Research
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• 제17권
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• pp.17-24
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• 2001

Risk assessment is useful tool making good decisions on the risks of certain hazardous com-pound and suggests safe margin through scientific process using toxicological data, statistical tool, exposure value and relevant variants. The goal of risk management is to protect the public health from hazardous compound based on result of risk assessment having reality. For the suggestion of exact man-aging information, risk assessment must be designed to represent a "plausible estimate" of the exposure to the individuals and to minimize uncertainty. Risk assessment methodology and knowledge are expected to change more rapidly than before and up-to-date methodology should be applied in regulatory aspects through the Agency. For the useful application of risk assessment, the communication between the risk assessor and the risk manager is needed before the initiation of the risk assessment and upon its completion. Generally, the risk assessment itself as a practical tool in the regulatory decision making process would be regarded with social economic impact.ic impact.

• 경영과학
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• 제17권1호
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• pp.31-40
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• 2000

With the rapidly changing external environment and the increasing internal process complexity more and more organizations are adopting the Electronic Approval System(EAS) for their competitiveness. This paper defines EAS as a core organizational communication medium investigates factors which influence EAS's use from a media rich-ness theory and shows sutiable EAS functions for equivocality resolution and uncertainty reduction. Results from the five EAS implementation sites show that most organizations use EAS only for tasks with low equivocality and low uncertainty. Additional functionalities such as video conferencing and database access were suggested for fu-ture EAS system to enhance their utilization for more cirtical and unstructed tasks.

• 한국정보통신학회논문지
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• 제14권1호
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• pp.259-266
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• 2010

본 논문에서는 각각의 지휘소에서 수행되는 지휘결심의 질적 측면에서 네트워크를 통해서 수집되고 공유되는 정보의 효과를 평가하는 방안을 도출하고자 한다. 이러한 효과는 각각의 지휘소에서 수행되는 지휘결심에 결정적인 정보 요소에 대한 불확실성의 감소를 통해서 수학적으로 측정할 수 있다. 각종 보고들이 점점 많아질수록 불확실성은 줄어들고, 정보의 양은 증가하게 된다. 이러한 경우에 개체들간의 협동 과정에 의한 효과를 엔트로피를 이용하여 지식 함수 측면으로 살펴보고자 한다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권1호
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• pp.78-82
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• 2002

In this paper, we have studied a numerical stability analysis method for the robust fuzzy feedback linearization regulator using Takagi-Sugeno fuzzy model. To analyze the robust stability, we assume that uncertainty is included in the model structure with known bounds. For these structured uncertainty, the robust stability of the closed system is analyzed by applying Linear Matrix Inequalities theory following a transformation of the closed loop systems into Lur'e systems.

• ETRI Journal
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• 제20권1호
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• pp.16-27
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• 1998

In this paper, we consider the acquisition performance of an IS-95 reverse link access channel slot as a function of system design parameters such as postdetection integration length and the number of access channel message block repetitons. The uncertainty region of the reverse link spreading codes compared to that of forward link is very small, since the uncertainty region of the reverse link is determined by a cell radius. Thus, the parallel acquisiton technique in the reverse link is more efficient than a serial acquisition technique in terms of implementation and of acquisition time. The parallel acquisition is achieved by a bank of N parallel I/Q noncoherent correlator are analyzed for band-limited noise and the Rayleigh fast fading channel. The detection probability is derived for multiple correct code-phase offsets and multipath fading. The probability of no message error is derived when rake combining, access channel message block combining, and Viterbi decoding are applied. Numerical results provide the acquisition performance for system design parameters such as postdetection integration length and number of access channel message block repetitions in case of a random access on a mobile station.

• Transactions on Control, Automation and Systems Engineering
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• 제4권4호
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• pp.324-329
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• 2002

In this paper, the guaranteed cost filtering design method for linear time delay systems with convex bounded uncertainties in discrete-time case is presented. The uncertain parameters are assumed to be unknown but belonging to known convex compact set of polytotype less conservative than norm bounded parameter uncertainty. The main purpose is to design a stable filter which minimizes the guaranteed cost. The sufficient condition for the existence of filter, the guaranteed cost filter design method, and the upper bound of the guaranteed cost are proposed. Since the proposed sufficient conditions are LMI(linear matrix inequality) forms in terms of all finding variables, all solutions can be obtained simultaneously by means of powerful convex programming tools with global convergence assured. Finally, a numerical example is given to check the validity of the proposed method.