• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.109-111
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• 2009

In this paper, we discuss how to design 2-wheeled mobile robot hard wares as reasonable and practical as possible. A segway type mobile robot consists of 2 wheels only, placed in parallel rather than horizon. 2-wheeled mobile robots make you overcome high cost and time consuming maintenance procedures of the robot by reducing the number of robot hardwares. The most challenging thing in a 2-wheeled mobile robot that has many more valid virtues than the traditional mobile robots is to make it balance itself whenever it stands still or goes forward. But balancing itself is not an easy matter and there are many researches and experiments on this issue. When researchers test theories on 2-wheeled mobile robots to improve its self balancing performance, they should consider how to design hard wares of that mobile robot. No matter how great those new theories are, if a testbed for those theories is not suitable, performance output would be poor and meaningless. In this point of view, to design a proper 2-wheeled mobile robot as a testbed is a very important issue with development of new theories. So we define 4 guide lines to design segway type mobile robots reasonably; about motor, battery, and MCU selection and shock-proof design with robust motor setting.

• The KSFM Journal of Fluid Machinery
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• v.14 no.5
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• pp.69-74
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• 2011

This paper deals with the detail rotordynamic analysis for the vertical rotor system as development of vertical sea water lift pump for FPSO deep well. In a vertical rotor system, since linearized stiffness and damping coefficients of fluid film bearing are no longer be valid, hence the transient response analysis considering a fluid film force for every journal position in the bearing needs to be required. In this study, the transient response analysis of the proposed vertical pump rotor system was carried out in dry-run and wet-run conditions, respectively. The results show that orbital vibration responses of the rotor system remain stable at rated speed and thereby operating reliability of the vertical rotor system is confirmed. To overcome complexity of calculation pr ocedure and time consuming calculation of transient analysis, the calculating technique of steady-state response analysis is also proposed. The results of steady-state response obtained by applying the proposed technique to the rotor system are good agreement with the reference results, that is, transient responses.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.3
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• pp.41-54
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• 2001

This paper propose an active rule and its semantic model integrating active rule system into temporal database. Most of previous works have been focused on condition action(CA) rule for temporal relations. However, proposed active rule model supports full SQL:3 trigger functionalitics including transition variable and table as well as tuple-level and statement-level active rules in E CA granularity. A bi-temporal concept of active rule and valid time event are also proposed newlv.

• Journal of Korea Game Society
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• v.14 no.4
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• pp.53-66
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• 2014

Despite the game market's expanding results from the increase of new users of mobile-game market, online-game market is faced with a stagnation. And the increase of income online-game's market share leads to decline of growth of the domestic online-game market. Online-game's growth potential is still valid, and the domestic online-games are still popular in foreign markets. But if the problem of domestic game market is not overcome, the falling behind in the competition is only a matter of time. The major problem is the lack of support measures and reduced competitiveness. On these issues, this research presents a plan to revitalizing of the online-game.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1262-1269
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• 2003

In structural optimization, static loads are generally utilized although real external forces are dynamic. Dynamic loads have been considered in only small-scale problems. Recently, an algorithm for dynamic response optimization using transformation of dynamic loads into equivalent static loads has been proposed. The transformation is conducted to match the displacement fields from dynamic and static analyses. The algorithm can be applied to large-scale problems. However, the application has been limited to size optimization. The present study applies the algorithm to shape optimization. Because the number of degrees of freedom of finite element models is usually very large in shape optimization, it is difficult to conduct dynamic response optimization with the conventional methods that directly threat dynamic response in the time domain. The optimization process is carried out via interfacing an optimization system and an analysis system for structural dynamics. Various examples are solved to verify the algorithm. The results are compared to the results from static loads. It is found that the algorithm using static loads transformed from dynamic loads based on displacement is valid even for very large-scale problems such as shape optimization.

• International journal of advanced smart convergence
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• v.5 no.2
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• pp.59-65
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• 2016

With the recent growth in cloud computing, big data processing and collaboration between businesses are emerging as new paradigms in the IT industry. In an environment where a large amount of data is generated in real time, such as SNS, big data processing techniques are useful in extracting the valid data. MapReduce is a good example of such a programming model used in big data extraction. With the growing collaboration between companies, problems of duplication and heterogeneity among data due to the integration of old and new information storage systems have arisen. These problems arise because of the differences in existing databases across the various companies. However, these problems can be negated by implementing the MapReduce technique. This paper proposes a collaboration system based on Database as a Service, or DBaaS, to solve problems in data integration for collaboration between companies. The proposed system can reduce the overhead in data integration, while being applied to structured and unstructured data.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.2
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• pp.1-9
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• 1989

This paper deals with the simplification and the conversion time reduction for the 12-channel TDM/FDM transmultiplexing system using the polyphase network and the FDCT. The prototype filter required in the digital polyphase network is designed based on interpolated FIR (IFIR) properites of the IFIR coefficients, the multiplication rate required in its implementaion is shown to be $0.1640{\times}10^6$ multiplications/sec. channel which reduces about 25% of the result obtained in the previous work. The result of computer simulation indicates that the proposed conversion method is valid.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.851-858
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• 2012

In this paper, we design a seismic data acquisition system(SDAS) and implement it. This system is essential for development of a noble local earthquake disaster preventing system in population center. In the system, we choose a proper MEMS-type triaxial accelerometer as a sensor, and FPGA and ARM processor are used for implementing the system. In the SDAS, each module is realized by Verilog HDL and C Language. We carry out the ModelSim simulation to verify the performances of important modules. The simulation results show that the FPGA-based data acquisition module can guarantee an accurate time-synchronization for the measured data from each axis sensor. Moreover, the FPGA-ARM based embedded technology in system hardware design can reduce the system cost by the integration of data logger, communication sever, and facility control system. To evaluate the data acquisition performance of the SDAS, we perform experiments for real seismic signals with the exciter. Performances comparison between the acquired data of the SDAS and the reference sensor shows that the data acquisition performance of the SDAS is valid.

• Structural Engineering and Mechanics
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• v.64 no.4
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• pp.473-485
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• 2017

An isolated building, composed of superstructure and isolation system which have very different damping properties, is typically non-classical damping system. This results in inapplicability of traditional response spectrum method for isolated buildings. A multidimensional response spectrum method based on complex mode superposition is herein introduced, which properly takes into account the non-classical damping feature in the structure and a new method is developed to estimate velocity spectra from the commonly used displacement or pseudo-acceleration spectra based on random vibration theory. The error of forced decoupling method, an approximated approach, is discussed in the viewpoint of energy transfer. From the base-isolated benchmark model, as a numerical example, application of the procedure is illustrated companying with comparison study of time-history method, forced decoupling method and the proposed method. The results show that the proposed method is valid, while forced decoupling approach can't reflect the characteristics of isolated buildings and may lead to insecurity of structures.

• Journal of Distribution Science
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• v.16 no.2
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• pp.25-33
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• 2018

Purpose - This study focused on the effect of counter-factual thinking on post-purchase behavior producing consumer regret at HMR selection and purchase. We have analyzed the factors that HMR production and distribution businesses should consider because distribution and marketing strategy reflecting consumers' demand. Research design, data, and methodology - For the purpose of carrying out this research, we conducted a direst structured questionnaire to students at 'J' college. A total of 237 valid questionnaires were collected for students and their parents at 'J' university. For the hypothesis test, exploratory factor analysis, t-test, regression and structure equation path analysis were performed. Results - The consumers who often resented HMR purchase did counter-factual thinking on post-purchase behavior were likely to do switching purchases. Counter-factual thinking on post-purchase behavior had a negative influence upon consumer's satisfaction with HMR safety and marketing characteristics. Conclusions - Consumers who had been satisfied to a certain degree might have cognitive dissonance of minor mistakes of HMR product were likely to have downward counter-factual thinking through contrast effects. Therefore, HMR producer and distribution businesses that had production, distribution and marketing strategy to satisfy consumers by raw material, freshness and safety were likely to switch to another product at one time mistake of selection, purchase and use.