• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.195-200
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• 1998

Since the neural network was introduced, significant progress has been made on data handling and learning algorithms. Currently, the most popular learning algorithm in neural network training is feed forward error back-propagation (FFEBP) algorithm. Aside from the success of the FFEBP algorithm, polynomial neural networks (PNN) learning has been proposed as a new learning method. The PNN learning is a self-organizing process designed to determine an appropriate set of Ivakhnenko polynomials that allow the activation of many neurons to achieve a desired state of activation that mimics a given set of sampled patterns. These neurons are interconnected in such a way that the knowledge is stored in Ivakhnenko coefficients. In this paper, the PNN model has been developed using the plasma enhanced chemical vapor deposition (PECVD) experimental data. To characterize the PECVD process using PNN, SiO$_2$films deposited under varying conditions were analyzed using fractional factorial experimental design with three center points. Parameters varied in these experiments included substrate temperature, pressure, RF power, silane flow rate and nitrous oxide flow rate. Approximately five microns of SiO$_2$were deposited on (100) silicon wafers in a Plasma-Therm 700 series PECVD system at 13.56 MHz.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.211-215
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• 2006

In this paper, design and applications of a generalized, versatile and customizable IF signal generator that can model the modernized GPS and Galileo signal is given. It generates IF sampled data that can be directly used by a software receiver. Entire constellation of satellites which is independent of satellite-user geometry is easily determined using a real or simulated ephemeris data. Since the IF center frequency, sampling frequency and quantization bit number are user location dependent parameters, their effects are also considered in IF signal generator. The generalized IF signal generator will be very well suited for the development phase of a software receiver due to its versatility. The full access to the sampling frequency, front-end filter definition and ADC parameters also offers a great opportunity for cost-effective analysis of tracking loops and error mitigation techniques at the receiver level. Interference sources can be easily added to the generator to simulate specific environments. This software IF signal generator can also be used to feed a multi-frequency multi-system software receiver for the prototyping of a combined GPS/Galileo receiver. The test result using the generated signals and a real software receiver shows the effectiveness of the implemented IF signal generator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1C
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• pp.59-66
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• 2007

This paper proposes a windowing method to reduce noise effect and bit synchronization error caused by tolerance of a tag-response signal for ISO/IEC 18000-6 type-B readers. A tag response signal has very weak power because of a back-scattering modulation scheme and thus may be sensitive to noise. In addition, bit tolerance admitted in a tag response signal requires robust timing synchronization because it affects readers' detection performance. To reduce the two undesirable effects in a tag signal, we acquire bit transition position by using variable windows from over-sampled data, and average whole data in one bit duration. With a hardware system adopting the proposed method, we tested and verified its performance.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.36-36
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• 2012

Drainage water in lowland paddy fields is quantitatively influenced recycle and/or repeated irrigation by irrigation facilities, i.e. pumps, check gates, small reservoirs and so on. In those drainage channels, nutrients accumulation and increasing organic matters are considered to be occurred, and water quality would be degraded not only environmental aspect but irrigation purpose. In general, Total Nitrogen (T-N) is interested water quality index in irrigation water, because high nitrogen concentration sometimes caused decreasing rice production by excess growth and fallen or degrading quality of taste, then, farmers would like to clear water less than 1mg/L of T-N concentration. In drainage channel, it is known that the nitrogen concentration change is influenced by physical, chemical and biological properties, i.e, stream or river bed condition, water temperature, other water quality index, and plant cover condition. In this study, discharge data (velocity and level) in a drainage channel was monitored by an Acoustic Doppler system and water quality was sampled at same time in 2011. So those data was analyzed by multi regression model to realize hydrological and environmental factors to influence with nitrogen concentration. The results showed the difference tendency between irrigation and non-irrigation period, and those influenced factors would be considered in water quality model developing in future.

• Journal of East-West Nursing Research
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• v.16 no.2
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• pp.179-189
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• 2010

Purpose: The purpose of this study was to investigate the relations among professionalism, organizational commitment and job satisfaction, and to the investigate the influencing factors of organizational commitment and job satisfaction among clinical nurses. Methods: The participants were 386 nurses sampled from Seoul and Gyeonggi provinces. A structured questionnaire was used to collect data, and the data were analyzed by applying t-test, ANOVA, Pearson correlation coefficient, and stepwise multiple regression with SAS 8.12. Results: A positive correlation existed among professionalism, organizational commitment and job satisfaction. Major factors that influenced organizational commitment were job satisfaction, religion, educational status, and a sense of calling (one of the subcategories of professionalism), which explained 54.1%. Major factors that affected job satisfaction were organizational commitment, educational status, and the subcategories of professionalism including a sense of calling, a service to the public, self-regulation and professional autonomy, which explained 60.8%. Conclusion: Based on the findings of this study, the professionalism is one of the critical factors linked to organizational commitment and job satisfaction among clinical nurses. In order to promote organizational commitment and job satisfaction among nurses, an appropriate practical support system, which is applicable to diverse conditions, should be developed and applied in nursing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.492-494
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• 2021

The decision tree technique is used as a classification technique in machine learning. However, the decision tree has a problem of consuming a lot of speed or resources due to the problem of overfitting. To solve this problem, there are bagging and boosting techniques. Bagging creates multiple samplings and models them using them, and boosting models the sampled data and adjusts weights to reduce overfitting. In addition, recently, techniques Xgboost have been introduced to improve performance. Therefore, in this paper, we collect wifi signal data for indoor positioning, apply it to the existing method and Xgboost, and perform performance evaluation through it.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.9
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• pp.23-32
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• 2015

In order to complete engineering works of the digital substation, Both Data transmission among a variety of IEDs and HMIs, and single line diagram of the substation might be done based on XML documents published in IEC 61850 international standards. This kind of XML based engineering process for the digital substation must be implemented not by manual written work but by the engineering tool using a computer. But most of the engineering tools do not support system based engineering works such as single line diagram of the substation but have only function to set IEDs as single device unit. Accordingly, this paper presents a new design method of the system based engineering description applicable to real IEC 61850 based substation through analyzing the current international standard and its sampled engineering file, and shows implementation of the engineering tool of the digital substation with the result of this study.

• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.1975-1987
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• 2005

An input time delay always exists in practical systems. Analysis of the delay phenomenon in a continuous-time domain is sophisticated. It is appropriate to obtain its corresponding discrete-time model for implementation via digital computers. In this paper a new scheme for the discretization of nonlinear systems using Taylor series expansion and the zero-order hold assumption is proposed. The mathematical structure of the new discretization method is analyzed. On the basis of this structure the sampled-data representation of nonlinear systems with time-delayed multi-input is presented. The delayed multi-input general equation has been derived. In particular, the effect of the time-discretization method on key properties of nonlinear control systems, such as equilibrium properties and asymptotic stability, is examined. Additionally, hybrid discretization schemes that result from a combination of the scaling and squaring technique (SST) with the Taylor series expansion are also proposed, especially under conditions of very low sampling rates. Practical issues associated with the selection of the method's parameters to meet CPU time and accuracy requirements, are examined as well. A performance of the proposed method is evaluated using a nonlinear system with time delay maneuvering an automobile.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.574-582
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• 2008

This paper shows the research about the development of software receiver processing Galileo E1B signal. it is introduced the structure of Galileo receiving software using sampled IF data as a program input. And the performance of SDR(Software Defined Radio) embodied using MATLAB tool is analyzed. Embodied SDR is modulated according to their roll and function.

• Journal of Korean Society of Transportation
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• v.23 no.2
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• pp.131-142
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• 2005

Punctuality of bus operation can be defined as "timely operation of buses according to their operation schedules." It tis often considered as one of the important measures of bus operation reliability in evaluating bus operation performance from the viewpoint of bus users. Passenger waiting times are severely influenced by the punctuality of bus operations. However, there exist many situations that predetermined schedules cannot be met. In these cases, other definitions of punctuality should be given. This paper is to develop punctuality indexes of bus operation based on various bus operating situations. Bus operation data sampled from Seoul bus system were analyzed to calculate punctuality indexes for a number of bus routes. Then, bus operation punctuality was characterized by various operating conditions. Several interesting results were obtained and explained.