• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.296-303
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• 2000

The purpose of this study is to find inelastic behavior and ductility capacity of reinforced concrete bridge columns under earthquake. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, due to the abrupt change in their stiffness local discontinuous deformation can be taken into account by introducing interface element. Also an analytical model is developed to express the confining effects of lateral tie which depend on the existence or nonexistence and the amounts of transverse confinement, etc. The proposed numerical method for inelastic behavior and ductility capacity of reinforced concrete bridge columns will be verified by comparison with reliable experimental results.

• Journal of Information Technology Services
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• v.13 no.2
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• pp.19-34
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• 2014

As the global smartphones market is growing at a brisk pace, their associated mobile applications are becoming increasingly ubiquitous in our daily life. The growth of mobile application business is explosive. Like other digital contents businesses, illegal downloads of copyrighted mobile applications become major obstacle in the future of the industry. In spite of anti-piracy efforts, the phenomenon has been getting worse. It is necessary to change the focus of current deterrence policies and strategies. This study investigates the factors influencing smartphone applications piracy behavior. For better understanding of illegal behavior, a research model of potential determinants for the piracy behavior is developed and empirically tested via path analysis using structural equation modeling. Findings show that social factors, beliefs concerning benefits from piracy, self-efficacy, and habit have significant effects on attitude toward smartphone application piracy. The result also shows perceived risks and facilitating conditions were not significantly related to their attitude. Implications for research and practice are discussed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.133-140
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• 2002

The purpose of this study is to investigate the seismic behavior of reinforced concrete bridge piers and to provide the data for developing improved seismic design criteria. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected. local discontinuity in deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel and concrete. The proposed numerical method for the prediction of seismic behavior for reinforced concrete bridge piers is veri fief by comparison with the reliable experimental results.

• International Journal of Control, Automation, and Systems
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• v.1 no.1
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• pp.111-118
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• 2003

This paper proposes a two dimensional behavior analysis method for fish in a water tank based on the ARX method and the Kalman filter algorithm using image processing technology. In modeling the behavior of fish, the input is denoted as the environmental change and uses M-sequence. The output is expressed by the partnership between fish. The behavior model of individual fish is identified by the ARX method. It is then estimated by the Kalman filter algorithm. Finally, the fish behavior is analyzed by FFT. To prove the effectiveness of the pro-posed algorithm, it is applied to two tilapias in a water tank with dimensions of 100cm$\times$100cm$\times$50cm. The effectiveness of the proposed method is demonstrated through ARX identification, estimation of Kalman filter, and FFT analysis.

• Journal of Environmental Science International
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• v.3 no.1
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• pp.11-16
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• 1994

Generally, it is difficult to predict water quality in a tidal river, because tidal flows make the transport phenomena more complicated. The purpose of this study is to clarify long-term mass transport in a tidal river through suggestion of simulation model. A simulation model based on a Lagrangian coordinate system, which has the advantage reducing numerical dispersion, was used to calculate changes in concentration of chlorides. Several field surveys were conducted to verify calculated results. Concludingly, long-term behavior of mas transport in a tidal river can be represented using the model.

• Geomechanics and Engineering
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• v.7 no.2
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• pp.213-231
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• 2014

An elastoplastic model for structured clays, which is formulated based on the fact that the difference in mechanical behavior of structured and reconstituted clays is caused by the change of fabric in the post-yield deformation range, is present in this paper. This model is developed from an elastoplastic model for overconsolidated reconstituted clays, by considering that the variation in the yield surface of structured clays is similar to that of overconsolidated reconstituted clays. However, in order to describe the mechanical behavior of structured clays with precision, the model takes the bonding and parabolic strength envelope into consideration. Compared with the Cam-clay model, only two new parameters are required in the model for structured clays, which can be determined from isotropic compression and triaxial shear tests at different confining pressures. The comparison of model predictions and results of drained and undrained triaxial shear tests on four different marine clays shows that the model can capture reasonable well the strength and deformation characteristics of structured clays, including negative and positive dilatancy, strain-hardening and softening during shearing.

• Information Systems Review
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• v.19 no.4
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• pp.183-209
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• 2017

With changes in information technology (IT), many innovative IT-based services, such as AirBnB, have become popular. Switching behavior toward new and innovative services become a major issue for managers who want to attract many customers. In response, many researchers have investigated why customers switch service providers. However, little research has been conducted on the processes of switching behavior for a hedonic service. To fill this research gap, this study aimed to identify the stages of switching behavior based on transtheoretical model. Furthermore, the factors affecting the service switching behavior in stages were identified on the basis of service provider switching model. This study also hypothesized the customer's switching behavior in accommodation sharing economy service and analyzed it empirically. Results showed that the factors affecting switching behavior differ across five stages. The present results can provide a basis to prevent switching behavior and reduce churn by analyzing the difference in switching behavior among stages. This study also helps managers who want to improve organizational performance by enhancing customer retention capability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1887-1898
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• 2018

In this paper, a method to classify insider threat activity is introduced. The internal threats help detecting anomalous activity in the procedure performed by the user in an organization. When an anomalous value deviating from the overall behavior is displayed, we consider it as an inside threat for classification as an inside intimidator. To solve the situation, Markov Chain Model is employed. The Markov Chain Model shows the next state value through an arbitrary variable affected by the previous event. Similarly, the current activity can also be predicted based on the previous activity for the insider threat activity. A method was studied where the change items for such state are defined by a transition probability, and classified as detection of anomaly of the inside threat through values for a probability variable. We use the properties of the Markov chains to list the behavior of the user over time and to classify which state they belong to. Sequential data sets were generated according to the influence of n occurrences of Markov attribute and classified by machine learning algorithm. In the experiment, only 15% of the Cert: insider threat dataset was applied, and the result was 97% accuracy except for NaiveBayes. As a result of our research, it was confirmed that the Markov Chain Model can classify insider threats and can be fully utilized for user behavior classification.

• Asia pacific journal of information systems
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• v.16 no.4
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• pp.103-119
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• 2006

One of the most important reasons for using online game is intrinsic motivation which relates the drive to perform a behavior for perceptions of pleasure and satisfaction from the behavior itself. Therefore, most studies for using online game have been based on theories for intrinsic motivation such as flow. However, such theories have some limitations for explaining social aspects of online games such as Massively Multiplayer Online Role Game (MMORPG), which provides a society for game players by using a virtual space for playing games so called 'persistent world'. Adaptive structuration theory (AST) is one of trying to capture the change of using IT due to social interactions between users and system. In order to explain online game players' behavior considering social interaction, we suggest a research model based on AST. Our model aims to investigate the relationship between appropriation which is determined by faithfulness of appropriation (FOA) and consensus on appropriation (COA) and performance which is represented by the relationship among perceived winning, flow, and intention of reuse. An empirical test of our model for 125 MMORPG users which is analyzed by Partial Least Square method shows very satisfactory and interesting results. While hypotheses suggested in our model are supported, the influence of COA on game performance is shown to be stronger than that of FOA.

• Korea journal of population studies
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• v.11 no.1
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• pp.97-116
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• 1988

This study examines the socioeconomic determinants of fertility behavior in Korea by developing a model which simultaneously takes into account both individual and community-level differences. It especially focuses on the micro-macro nexus of fertility behavior depending on social contexts. This study utilizes micro data obtained from the 1974 Korean National Fertility Survey(KNFS), and macro data obtained from Korean government statistics. The framework of the model is formalized as a set of structural equations modelling the fertility process. The model is formed on a cohort-specific processual basis and is restricted to five-year birth cohorts. Three cohorts of women are studied : those aged 30-34, 35-39, and 40-44. The model includes three fertility-process components : age at first birth, early fertility, and later fertility, which are defined by reference to the age of the mother. The results of this study indicate that socioeconomic development in Korea results in increased age at first birth and reduced numbers of children per couple. In addition to the developmental change, Korea's fertility decline is found to be facilitated by family planning programs. As expected, the effect of family planning on fertility is greater among better-educated women than among poorly educated women. The inconsistent but suggestive result, however, is that the effect of socioeconomic development on fertility is greater among less-privileged women than among more-previleged women.