• Journal of Industrial Technology
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• v.30 no.A
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• pp.111-117
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• 2010

To improve the performance of the prediction system, the system should reflect well the uncertainty of nonlinear data. Thus, this paper presents multiple prediction systems based on Type-2 fuzzy sets. To construct each prediction system, an Interval Type-2 TSK Fuzzy Logic System and difference data were used, because, in general, it has been known that the Type-2 Fuzzy Logic System can deal with the uncertainty of nonlinear data better than the Type-1 Fuzzy Logic System, and the difference data can provide more steady information than that of original data. Also, to improve each rule base of the fuzzy prediction systems, the HCBKA (Hierarchical Correlation Based K-means clustering Algorithm) was applied because it can consider correlationship and statistical characteristics between data at a time. Subsequently, to alleviate complexity of the proposed prediction system, a system selection method was used. Finally, this paper analyzed and compared the performances between the Type-1 prediction system and the Interval Type-2 prediction system using simulations of three typical time series examples.

• Transactions of Materials Processing
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• v.9 no.2
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• pp.165-170
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• 2000

In this paper, a general approach to structural analysis of forging die sets is presented and the related design system, AFDEX/DIE, is introduced. Structural analysis of die sets is conducted by the finite element method considering both contact problem and shrink fit. In the approach, amount of shrink fit is controlled by thermal load, i.e., temperature difference between die insert and shrink rings. The loading conditions are extracted automatically from the simulation results obtained by a rigie-thermoviscoplatic finite element method. Typical application examples are given, which show the applicability of the approach and the related program.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.4
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• pp.85-95
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• 1998

In this paper, a new watermarking method for a copy protectionof images is proposed. The proposed method adaptively embeds a watermark in the frequency domain of images using human visual system model. For this purpose, the Just Noticeable Differences(JNDs) of each frequency coeffeicient value of a luminance plane is first found using Watson and Solomon's visual system model. An invisible maximum watermark value with is different in every position according to the characteristics of images is determined usig JND and Minkowski metric. A low frequency domain is divided into two sets based on a PN-sequence to protect thewatermark from the attack. The watermarks are added to one set of coefficients and detecting a watermark, the difference between the mean values of absolute coefficient values of both sets is calculated. The embedded watermark is tested using statistical hypothesis based on test static dertermined by the ean difference. To demonstrate the perfromance of the proposed method, the new watermarking method is applied to a high frequency image and low frequency images. Experimenatal results show the watermark is invisible and robust to JPEGlossy compression and noise.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.6
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• pp.747-752
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• 1998

Ultrasonic sensors have been widely used to recognize the working environment for a mobile robot. However, their intrinsic problems, such as specular reflection, wide beam angle, and slow propagation velocity, require an excessive number of sensors to be integrated for achieving the sensing goal. This paper proposes a new measurement scheme which uses only two sets of ultrasonic sensors to determine the location and the type of a target surface. By measuring the time difference between the returned signals from the target surface, which are generated by two transmitters with 1 ㎳ difference, it classifies the type and determines the size of the target surface. Since the proposed sensor system uses only two sets of ultrasonic sensors to recognize and localize the target surface, it significantly simplifies the sensing system and reduces the signal processing time so that the working environment can be recognized in real time.

• Communications of the Korean Mathematical Society
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• v.31 no.1
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• pp.41-52
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• 2016

In the present paper, by generalizing the definition of the zero-difference balanced (ZDB) function to be the G-ZDB function, several classes of G-ZDB functions are constructed based on properties of cyclotomic numbers. Furthermore, some special constant composition codes are obtained directly from G-ZDB functions.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.3
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• pp.292-299
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• 2004

For Web System composed of a variety of hardware, software and network system, there is a wide difference in price, function and capacity. In addition, it is important to select the most suitable system when web system is constructed as the claim of high-quality web service from user has increased. Data of bench-marking is usually employed when the system is selected. Evaluation with the result of bench-marking, however, is not easy at web situation composed of a variety of systems. In this paper, first integrated bench-marking of hardware, software and network system metric were determined, and the plan to effectively compare and evaluate the result of bench-marking by using fuzzy set were offered.

• Structural Engineering and Mechanics
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• v.53 no.2
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• pp.249-260
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• 2015

Damage detection based on a reference set of measured data usually has the problem of different environmental temperature in the two sets of measurements, and the effect of temperature difference is usually ignored in the subsequent model updating. This paper attempts to identify the structural damage including the temperature difference with artificial measurement noise. Both local damages and the temperature difference are identified in a gradient-based model updating method based on dynamic response sensitivity. The sensitivities of dynamic response with respect to the system parameters and temperature difference are calculated by direct integration method. The measured dynamic responses of the structure from two different states are used directly to identify the structural local damages and the temperature difference. A single degree-of-freedom mass-spring system and a planar truss structure are studied to illustrate the effectiveness of the proposed method.

• Journal of the Korean Society for Library and Information Science
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• v.6
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• pp.87-103
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• 1979

Information storage and retrieval is a part of general communication process. In the Shannon's information theory, information contained in a message is a measure of -uncertainty about information source and the amount of information is measured by entropy. Indexing is a process of reducing entropy of information source since document collection is divided into many smaller groups according to the subjects documents deal with. Significant concepts contained in every document are mapped into the set of all sets of index terms. Thus index itself is formed by paired sets of index terms and documents. Without indexing the entropy of document collection consisting of N documents is $log_2\;N$, whereas the average entropy of smaller groups $(W_1,\;W_2,...W_m)$ is as small $(as\;(\sum\limits^m_{i=1}\;H(W_i))/m$. Retrieval efficiency is a measure of information system's performance, which is largely affected by goodness of index. If all and only documents evaluated relevant to user's query can be retrieved, the information system is said $100\%$ efficient. Document file W may be potentially classified into two sets of relevant documents and non-relevant documents to a specific query. After retrieval, the document file W' is reclassified into four sets of relevant-retrieved, relevant-not retrieved, non-relevant-retrieved and non-relevant-not retrieved. It is shown in the paper that the difference in two entropies of document file Wand document file W' is a proper measure of retrieval efficiency.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.4
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• pp.329-335
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• 2003

This study is on a experiment which shows to defrost automatically on the optimum time regardless of defrosting method. The result shows that the more defrost layers increase in fin tubes of evaporation, the less the section of the circulating air reduce. Thickness of the frost formation increases, so a pressure difference of ventilation increase, as a result automatic defrosting system sets the time COP drops suddenly up optimum time. Automatical defrosting system can find out the initial related current of evaporator fan motor and the value of load current in the optimum time. And it sets defrosting time, evaporating temperature, and temperature in refrigerator up system requiring value. Consequence of this experiment is that energy consumption with defrost load gets effect of reduction of eleven percent per 25.4 hours compared with common defrosting.

• Journal of the Korean Society for information Management
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• v.14 no.2
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• pp.123-141
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• 1997

This study examined the extent to which variations in relevance assessments affect the evaluation of the performance of full-text retrieval system. Four sets of relevance judgments obtained by examining the full-text of documents were used to test the retrieval effectiveness. There was no noticeable difference in retrieval performance among the four relevance judgment sets. It implies that a variety of definitions of relevance has no effect on the evaluation of the performance of the full-text retrieval system. Furth r retrieval experiments on this topic incorporating relevance feedback, which is one of the sophisticated retrieval techniques using relevance information, are suggested.