• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.25-34
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• 2011

In this paper, In this paper, we propose a Cooperative Routing Protocol (CooRP) for supporting network convergence and transmission services efficiently in mobile ad-hoc wireless sensor networks with Rayleigh fading environments. The main contributions and features of this paper are as follows. First, the routing routes are decided on route stability based on entropy concepts using mobility of nodes within the direction guided line region to increase the operational lifetime of routes as well as reduce control overhead for route construction. Second, a cooperative data transmission strategy based on the constructed stable routing route is used to increase packet delivery ratio with advanced SNR. Third, a theoretical analysis for cooperative data transmission of the proposed CooRP with outage probability is presented. The performance evaluation of the proposed CooRP is performed via simulation using OPNET and analysis. The results of performance evaluation show that the proposed CooRP by using stable routing routes and cooperative transmission can increase packet delivery ratio efficiently.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.37-40
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• 2001

This paper describes the selection and evaluation of RP processes. Major rapid prototyping processes such as SLS, SLA, FDM and LOM, which are wide spread in use are selected. A test part, which includes various primitives, is designed in order to evaluate these RP processes. Measurement of the test part is automated by using a CMN program. To visualize and analyze measured data, Microsoft Access and Visual C++ are used. Also, from measured data obtained, TOPSIS, one of the decision making methods, and Shannon Entropy is used to select an appropriate RP process for specific application.

• Journal of Korea Multimedia Society
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• v.15 no.6
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• pp.701-710
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• 2012

Retinitis Pigmentosa(RP) is a common hereditary disease. While they have been normally living, those who have this symptom feel frustration and pain by the damage of visual acuity. At the national level, the loss of the economic activity due to the reduction of economically active population will be also greater. There is an urgent need for the base study that can provide the clinical prognosis information of RP disease. In this study, we suggest that it is possible to predict prognosis through the pattern classification of RP data. Statistical processing results through statistical software like SPSS(Statistical Package for the Social Service) were mainly applied for the conventional study in data analysis. However, machine learning and automatic pattern classification was applied to this study. SVM(Support Vector Machine) and other various pattern classifiers were used for it. The proposed method confirmed the possibility of prognostic prediction based on the result of automatically classified RP data by SVM classifier.

• Journal of Korean Society of Transportation
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• v.28 no.4
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• pp.119-128
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• 2010

Mode choice behavior is associated with travelers' latent behavior that is an unobservable preference to travel behavior or mode characteristics. This paper specifically addresses the problem of unobservable factors, that is latent behavior, in mode choice models. Consideration of latent behavior in mode choice models reduces the errors that come from unobservable factors. In this study, the authors defined the latent variables that mean a quantitative latent behavior factors, and developed the combined RP/SP model with latent variables using the mode choice behavior survey data. The data has traveler's revealed preference of existent modes along the Han River and stated preference of new water transit on the Han River. Also, The data has travelers' latent behavior. Latent variables were defined by factor analysis using the latent behaviour data. In conclusion, it is significant that the relationship between traveler's latent behavior and mode choice behavior. In addition, the goodness-of-fit of the mode choice models with latent variables are better than the model without latent variables.

• Convergence Security Journal
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• v.2 no.2
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• pp.19-27
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• 2002

This paper proposes a group key management protocol for a secure of all the multicast user in PIM-SM multicast group communication. Each subgroup manager gives a secure key to it's own transmitter and the transmitter compress the data with it's own secure key from the subgroup manager. Before the transmitter send the data to receiver, the transmitter prepares to encrypt a user's service by sending a encryption key to the receiver though the secure channel, after checking the user's validity through the secure channel. As the transmitter sending a data after then, the architecture is designed that the receiver will decode the received data with the transmitter's group key. Therefore, transmission time is shortened because there is no need to data translation by the group key on data sending and the data transmition is possible without new key distribution at path change to shortest path of the router characteristic.

• Convergence Security Journal
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• v.2 no.1
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• pp.99-107
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• 2002

This paper proposes a group key management protocol for a secure of all the multicast user in PIM-SM multicast group communication under electronic commerce. Each subgroup manager gives a secure key to it's own transmitter and the transmitter compress the data with it's own secure key from the subgroup manager. Before the transmitter send the data to receiver, the transmitter prepares to encrypt a user's service by sending a encryption key to the receiver though the secure channel, after checking the user's validity through the secure channel. As the transmitter sending a data after then, the architecture is designed that the receiver will decode the received data with the transmitter's group key. Therefore, transmission time is shortened because there is no need to data translation by the group key on data sending and the data transmition is possible without new key distribution at path change to shortest path of the router characteristic.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.265-274
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• 2017

For accurate demand forecasting of railway logistics, we estimated intercity freight mode choice models based on the binary logit model and using production-consumption data from the Korea Transport Database. We estimated two types of models and compared the results by major item of railway logistics, such as container, cement, and steel: 1) The aggregate freight mode choice models are based on the revealed preference (RP) data and 2) The disaggregate models are based on the stated preference (SP) data. With respect to the container, the travel time variable was found to be statistically significant; however, the travel cost variable was not statistically significant in the RP model, while the travel cost variable was statistically significant in the SP model. For cement and steel, the travel cost variables were statistically significant but the travel time variables were not statistically significant in either the RP or the SP models. These results are inconsistent with results from previous studies based on SP data, which showed that the travel time variables were significant. Consequently, it can be concluded that the travel time factor should be considered in container transport, but that this factor is negligible for cement and steel transport.

• International Journal of Highway Engineering
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• v.17 no.6
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• pp.65-73
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• 2015

PURPOSES : This study tries to develop the accident models of 4-legged signalized intersections in Busan Metropolitan city with random parameter in count model to understanding the factors mainly influencing on accident frequencies. METHODS : To develop the traffic accidents modeling, this study uses RP(random parameter) negative binomial model which enables to take account of heterogeneity in data. By using RP model, each intersection's specific geometry characteristics were considered. RESULTS : By comparing the both FP(fixed parameter) and RP modeling, it was confirmed the RP model has a little higher explanation power than the FP model. Out of 17 statistically significant variables, 4 variables including traffic volumes on minor roads, pedestrian crossing on major roads, and distance of pedestrian crossing on major/minor roads are derived as having random parameters. In addition, the marginal effect and elasticity of variables are analyzed to understand the variables'impact on the likelihood of accident occurrences. CONCLUSIONS : This study shows that the uses of RP is better fitted to the accident data since each observations'specific characteristics could be considered. Thus, the methods which could consider the heterogeneity of data is recommended to analyze the relationship between accidents and affecting factors(for example, traffic safety facilities or geometrics in signalized 4-legged intersections).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.83-86
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• 1997

Even as many methods and technologies have been introduced on data generation, parts orientation and layer slicing to acquire the rapid prototyping(RP) parts that have useful surface to satisfy customers' needs such as stylingldesign verification directionlindirect tooling directly from the RP machine, these trials continue to suffer from the surface roughness due to the build characteristics of RP technology. A new postprocess finishing method is suggested in this paper to overcome the surface roughness problem on the surface of the RP parts. To prevent deterioration of dimensional accuracy from the conventional grinding-only, and coating-grinding methods, 4-step surface finishing process is applied. To satisfy the various requirements from the RP oriented industrial f elds, effective procedure, coating material, grmd~ng tools and methods are employed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.632-635
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• 2002

There are more than five dozen different RP(rapid prototyping) systems in the world and they are fairly expensive. All those systems have different capabilities and requirements in that each of them gives different tolerance, application field and part strength, etc. This situation may cause a problem of selecting an appropriate RP system. This paper presents an expert system, utilizing an algorithm that is composed up of rules to derive recommendations and answers to queries of the RP users. The expert system incorporates RP machines commercially available and adopts multi-selection criteria, namely, machine price, accuracy, build size, adopted process, etc. In the expert system, forward reasoning method is adopted and external spreadsheet for sub-data of the RP systems is used. The rules and knowledge are obtained from interviews and discussions with RP vendors and users, appropriate research publications and other reference materials.