• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.4
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• pp.170-181
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• 2009

When a slow-moving vehicle occupies one of the lanes of a multi-lane highway, it often causes queuing behind, unlike one is caused by an actual stoppage on that lane. This happens when the traffic flow rate upstream from the slow vehicle exceeds a certain critical value. This phenomena is called as the Moving Bottleneck, defined by Gazis and Herman (1992), Newell (1998) [3], and Munoz and Daganzo (2002), who conducted the flow estimates of upstream and downstream and considered slow-moving vehicle speed and the flow ratio exceeding slow vehicle and the microscopic traffic flow characteristics of moving bottleneck. But, a study of delay on moving bottleneck was not conducted until now. So this study provides a average delay time model related to upstream flow and the speed of slow vehicle. We have chosen the two-lane highway and homogeneous traffic flow. A slow-moving vehicle occupies one of the two lanes. Average delay time value is a result of AIMSUN[9], the microscopic traffic flow simulator. We developed a multiple regression model based on that value. Average delay time has a high value when the speed of slow vehicle is decreased and traffic flow is increased. Conclusively, the model is formulated by the negative exponential function.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.507-514
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• 2003

Most of CAE analyses for injection molding have been based on the Mele Shaw's approximation: two-dimensional flow analysis. in some cases, that approximation causes significant errors due to loss of the geometrical information as well as simplification of the flow characteristics in the thickness direction. Although injection molding analysis software using three-dimensional solid elements has been developed recently, such as Moldflow Flow3D, it does not contain a deformation analysis function yet. The present work covers three-dimensional deformation analysis or injection molded plastic parts using solid elements. A numerical scheme for deformation analysis has bun proposed from the results of injection molding analysis using Moldflow Flow3D. The accuracy of the proposed approach has been verified through a numerical analysis of rectangular plates with various thicknesses in comparison with the classical shell-based approach. In addition, the reliability of the approach has also been proved through an industrial example. an optical plastic lens, in comparison of real experiments.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.50-66
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• 2010

In this study, we performed a GIS-based debris flow simulation using the high-resolution airborne LiDAR DEM in order to establish the effective and resonable debris prevention plans in Korea. To do so, we set a study area to an specific region over Pyeochang-gun in Kangwon-do which showed the extreme rugged distribution of topography and simulated a possibility of debris flow occurrence in this area using a GIS-based numerical simulation program which was developed by applying the finite difference method. After that, we also performed the debris flow simulation by SINMAP and geomorphic analysis method in the same region and compared each result with that of GIS-based debris simulation for verifying the reliability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2792-2799
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• 2015

In this paper, we utilize source mel-frequency cepstral coefficients (SMFCCs), skewness, and kurtosis extracted in glottal flow signals to improve speaker recognition performance. Generally, because the high band magnitude response of glottal flow signals is somewhat flat, the SMFCCs are extracted using the response below the predefined cutoff frequency. The extracted SMFCC, skewness, and kurtosis are concatenated with conventional feature parameters. Then, dimensional reduction by the principal component analysis (PCA) and the linear discriminat analysis (LDA) is followed to compare performances with conventional systems under equivalent conditions. The proposed recognition system outperformed the conventional system for large scale speaker recognition experiments. Especially, the performance improvement was more noticeable for small Gaussan mixtures.

• International Journal of Highway Engineering
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• v.14 no.6
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• pp.183-190
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• 2012

PURPOSES : The fundamental diagram provides basic information necessary in the analysis of traffic flow and highway operation. When traffic flow is congested, the density-flow points in the fundamental diagram are widely scattered and move in a stochastic manner. This paper investigates the pattern of density-flow point transitions and identifies car-following behaviors underlying the density-flow transitions. METHODS : From a microscopic analysis of 722 fundamental diagrams of NGSIM data, a total of 20 transition patterns of fundamental diagrams are identified. Prominent features of the transition patterns are explained by the behavior of the leader and follower. RESULTS : It is found out that the average speed and the speed difference between the leader and the follower critically determine the density-flow transition pattern. The density-flow path is very sensitive to the values of vehicle speed and spacing especially at low speed and high density such that most fluctuations in the fundamental diagram in the congested regime is due to the noise of speed and spacing variations. CONCLUSIONS : The result of this study suggests that the average speed, the speed difference between the leader and the follower, and the random variations of speed and spacing are dominant factors that explain the transition patterns of a fundamental diagram.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.3
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• pp.205-212
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• 2014

In this paper, sunroof buffeting analysis for Hyundai simple model(HSM) is studied computationally. For validation, the velocity profile of boundary layer around the opening of HSM was obtained and compared with experimental results. The analysis of sunroof buffeting is done in two parts. First a steady state solution is obtained using the Reynolds Averaged Navier Stokes (RANS) solver, and then the computed flow field information is used as input for CAA++. Second transient simulation by CAA++ is performed for the peak sound pressure levels and peak frequencies of buffeting noise over the ranges of flow velocities. The benchmark results of frequency and sound pressure levels showed the general phenomena and matched well with the experimental data obtained by Hyundai Motor Car.

• The Journal of Information Systems
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• v.24 no.2
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• pp.97-116
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• 2015

Purpose This study suggested the four forms of inter-organizational relationships(IORs): partnerships, inter-dependence relationship, trust relationship, and market relationship. The purposes of this study include the demonstration of four forms of IORs and the investigation of the relationships among forms of IORs, inter-organizational information flow(IOIF), kinds of e-commerce strategies, and the supply-chain performance of a firm. Design/methodology/approach The empirical data were collected through post-survey. 92 survey data were collected. With a cluster analysis, we confirmed four types of IORs, and the relationships among critical variables. Findings The results of cluster analysis showed that according to the types of IORs, the frequency and quality of IOIF are different. Appropriate kinds of e-commerce strategies were examined under the each types of IORs, which cause specific patterns of IOIF. It was found that the adoption of e-procurement strategy can improve the supply-chain performance of a firm in trust relationship. It was also observed that under partnerships, the use of e-partnerships strategy can contribute to the improvement of supply-chain performance.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.229-238
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• 2018

The purpose of this study is to investigate the mediating effect of learners' learning flow in the effect of presence on academic achievement in web-based e-learning. For this purpose, this study analyzed the influencing relationship between the each factor based on the structural model with the learning flow as a mediator variable. Based on existing theoretical studies, learning satisfaction and academic achievement, which represent learning outcomes, are set as dependent variables, and teaching presence, cognitive presence, and social presence are set as independent variables. Data collected from a total of 256 e-learning learners were used in the analysis of this study. According to the results of the analysis, teaching presence, cognitive presence, and social presence were found to have a significant effect on academic achievement when a learning flow is a mediator variable. Concretely, teaching presence, cognitive presence, and social presence have a positive effect on the learning flow, while learning flow has a positive effect on learning satisfaction. On the other hand, learning flow has a negative effect on academic achievement. As a result of verifying the mediating effect of learning flow on the relationship between presence, learning satisfaction, and academic achievement, there was meditating effect in the aggregate. This study implies that in order to increase the level of learning satisfaction and academic achievement, it is necessary to make the teaching-learning design in the provision of contents and materials for e-learning so that the learner can feel the presence. The results of this study can be used as a basic data for seeking support and promotion strategies for enhancement of future learning flow and presence.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.962-965
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• 2008

효율적인 네트워크 관리를 위해서는 해당 네트워크의 트래픽 분석 정보가 필요하다. 트래픽을 분석함에 있어 네트워크의 전체 트래픽에 대한 분석도 중요하지만, 총 호스트의 수, 호스트별 트래픽 현황, 호스트의 사용 중인 서비스 파악 등 호스트를 기반으로 한 트래픽 분석의 중요성이 날로 증가하고 있다. 본 논문에서는 호스트 트래픽 분석이 어떠한 정보를 제공해야 되는지 살펴보고, 해당 정보를 제공하는 Enterprise 네트워크 트래픽 분석 시스템을 설계하고 구현한 내용을 기술한다. 본 논문에서 설계 및 구현한 시스템은 기존의 Enterprise 네트워크에 적합한 Flow 기반의 실시간 트래픽 모니터링 시스템[1]을 확장시킨 형태로 호스트 트래픽 분석에 필요한 DB구성과 분석 정보 표현, 그리고 트래픽 추이 그래프 생성에 따른 유의 사항과 해결책을 제시한다. 본 논문에서 구축한 시스템은 학교 Campus 네트워크를 대상으로 구축되었다.

• Journal of the Korea Society of Computer and Information
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• v.6 no.1
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• pp.74-81
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• 2001

In this paper. the architecture of a high-speed ATM router using ATM switch is studied and the performance of the high-speed ATM router is analyzed through simulation. The high-speed ATM router using ATM switch is able to reduce the load of router and the processing time of a packet in the router. The size of router buffers has been studied through simulation processes for the analysis of performance capacity in due course of making changes in routing time(RT), which is the performance capacity parameters of high-speed ATM routers, flow table size(FS), flow live time(FT) and input circuit efficiencies. The result of this study can be used as the source material for analyzing the suitability of equipment in upgrading networks and applying high-speed ATM routers by using ATM switches.