• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.8
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• pp.368-373
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• 2002

The inverse z-transform of a z-domain expression of a sequence can be Performed in many different methods among which the recursive computational method is based on the difference equation. In applying this method, a few initial values of the sequence should be obtained separately. Although the existing method generates the right initial values of the sequence, its derivation and justification are not theoretically in view of the definition of z-transform and its shift theorems. In this paper a general approach for formulating a difference equation and for obtaining required initial values of a sequence is proposed, which completely complies to the definition of the z-transform and an interpretation of the validity of the existing method which is theoretically incorrect.

• The Journal of the Korean dental association
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• v.52 no.3
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• pp.147-152
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• 2014

Recently the patient exposure by medical and dental x-ray examination has grown rapidly and diagnostic radiology represents the largest source of man-made radiation. For the patient protection, the principle of justification and optimization should be followed. All the radiographic examinations have to show a potential benefit to the patient weighing against the potential risk. After they are justified, the radiographic exposure should be kept as low as reasonably achievable, taking into account economic and social factors. For the safe use of radiation in dentistry, the radiation safety management in accordance with the legislation is important. The present status and the future of radiation safety management in dental radiology in Korea and other country will be discussed.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.56-58
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• 2005

This paper for the Train control system which has been used in the railway system for the purpose of headway control is regarded as safety-critical system, which is based on embedded controller. Therefore, for the maintainability, the maintenance time shall be predicted correctly in order to improve availability of railway system and the predictive values shall be proved through the test. In conclusion, for the maintainability of train control system, the solution for exact prediction based on related international standard and the system for justification of derived predictive values shall be proposed.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.67.5-67
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• 2001

A closed loop system with a linear plant and nonlinearity in the feedback connection is analyzed for its quasi-static orbital stability by a state-space approach. First a periodic orbit is assumed to exist in the loop which is determined by describing function method for the given nonlinearity. This is possible by selecting a proper nonlinearity and a rigorous justification of the describing function method.[1-3, 18, 20]. Then by introducing residual operator, a linear perturbed model can be formulated. Using various transformations like a modified eigenstructure decomposition, periodic-averaging, charge of variables and coordinate transformation, the stability of the periodic orbit, as a solution of harmonic balance, can be shown by investigating a simple scalar function and result of linear algebra. This is ...

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.162.1-162
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• 2001

In this paper, the adaptive fuzzy system is used as an adaptive approximator for robot nonlinear dynamic. A theoretical justification for the adaptive approximator is proving that if the representive point(RP or switching function) and its derivative in sliding mode control are used as the inputs of the adaptive fuzzy system, the adaptive fuzzy system can approximate robot nonlinear dynamics in the neighborhood of the switching surface. Thus the fuzzy controller design is greatly simplified and at the same time, the fuzzy control rule can be obtained easily by the reaching condition. Based on this, a new method for designing an adaptive fuzzy control system based on sliding mode is proposed for the trajectory tracking control of a robot with unknown nonlinear dynamics.

• Journal of applied mathematics & informatics
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• v.26 no.5_6
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• pp.1169-1183
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• 2008

In this paper, a method to find the weighted possibilistic variance and moments about the mean value of fuzzy numbers via applying a difuzzification using minimizer of the weighted distance between two fuzzy numbers is introduced. In this way, we obtain the nearest weighted point with respect to a fuzzy number, this main result is a new and interesting alternative justification to define of weighted mean of a fuzzy number. Considering this point and the weighted distance quantity, we introduce the weighted possibilistic mean (WPM) value and the weighted possibilistic variance(WPV) of fuzzy numbers. This paper shows that WPM is the nearest weighted point to fuzzy number and the WPV of fuzzy number is preserved more properties of variance in probability theory so that it can simply introduce the possibilistic moments about the mean of fuzzy numbers without problem. The moments of fuzzy numbers play an important role to estimate of parameters, skewness, kurtosis in many of fuzzy times series models.

• Asia pacific journal of information systems
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• v.20 no.3
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• pp.91-114
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• 2010

An IT system within a company play increasingly important role as a significant part of corporate assets. The IT system possesses an extraordinary ability to improve an organization's efficiency, effectiveness and productivity by providing competitive advantages and improving strategic business decision capabilities. Indeed, providing a more secure IT environment, improving employee productivity and enhancing business process and strategic decision capabilities are key areas to improve corporate performance. However, existing research on IT ROI of return on IT investments does not provide solid justification to stakeholders. In this paper, we analyze the IT investment during the past 28 years from 1982 to 2009 and present the results in two dimensions. First, we show the IT solution implementation analysis by years and industries based on 1,240 IT success cases from 8 different sources such as major Korea IT newspaper, IT magazines, and IT vendors. Then, the paper presents the relationship between IT capability through IT success cases and corporate business performance among 32 industries.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.771-774
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• 1999

This paper presents a new timing structure for real time communications and its performance analysis. The cycle time consists of several "one time slot" which may be an interval defined by a synchronous traffic part followed by an asynchronous traffic part. If a station receives a token within a synchronous interval, it transmits its synchronous message if any, otherwise it may transmit an asynchronous message. This scheme is different from usual allocation schemes which divide one cycle into alternating synchronous and asynchronous subslots. This protocol is designed to prevent low priority messages from delaying too much due to lots of high priority messages. We propose the algorithm and show its justification by simulation.

• Nuclear Engineering and Technology
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• v.47 no.2
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• pp.212-218
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• 2015

We describe a comparative analysis of different tools used to assess safety-critical software used in nuclear power plants. To enhance the credibility of safety assessments and to optimize safety justification costs, $Electricit{\acute{e}}$ de France (EDF) investigates the use of methods and tools for source code semantic analysis, to obtain indisputable evidence and help assessors focus on the most critical issues. EDF has been using the PolySpace tool for more than 10 years. Currently, new industrial tools based on the same formal approach, Abstract Interpretation, are available. Practical experimentation with these new tools shows that the precision obtained on one of our shutdown systems software packages is substantially improved. In the first part of this article, we present the analysis principles of the tools used in our experimentation. In the second part, we present the main characteristics of protection-system software, and why these characteristics are well adapted for the new analysis tools. In the last part, we present an overview of the results and the limitations of the tools.

• Journal for History of Mathematics
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• v.10 no.1
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• pp.1-11
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• 1997

In this paper, we investigate a relation between the history of western logic and religion. Logic, as distinct from theology, began in Greece in the sixth century B. C. After running its course in antiquity, it was again submerged by theology as Christianity rose and Rome fell. Its second great period, from the eleventh to the fourteenth centuries, was dominated by the Catholic church, except for a few great rebels, such as the Emperor Frederick II(1195-1250). This period was brought to an end by the confusion that culminated in the Reformation. The third period, from the seventeenth century to the present day is dominated by science; traditional religious beliefs remain important but are felt to need justification, and are modified wherever science seems to make this imperative.