• Water for future
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• v.28 no.4
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• pp.125-136
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• 1995

ELM, a characteristic line based method, was applied to advection-dispersion equation, and the results obtained were compared with those of Eulerian schemes(Stone-Brian and QUICKEST). The calculation methods consisted of Lagrangian interpolation scheme and cubic spline interpolation scheme for the advection calculation, and the Crank-Nicholson scheme for the dispersion calculation. The results of numerical methods were as follows: (1) for Gaussian hill: ELM, using Lagrangian interpolation scheme, gave the most accurate computational result, ELM, using cubic spline interpolation scheme, and QUICKEST scheme gave numerical damping for Peclet number 50. Stone-Brian scheme gave phase shift introduced in the numerical solution for Peclet number 10 and 50. (2) for advanced front: All schemes gave accurate computational results for Peclet number 1 and 4. ELM, Lagrangian interpolation scheme, and Stone,Brian scheme gave dissipation error and ELM, using cubic spline interpolation scheme, and QUICKEST scheme gave numerical oscillation for Peclet number 50.

• Convergence Security Journal
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• v.20 no.1
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• pp.9-14
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• 2020

There have been many papers on minimalism of cryptography. Secure minimal block cipher is one of these topics and Even and Mansour suggested a simple block cipher. The Even-Mansour scheme is a block cipher with one permutation and two whitening keys. Studying related to the Even-Mansour scheme gives great insight into the security and design of block cipher. There have been suggested many trials to analyze the security of the Even-Mansour scheme and variants of the Even-Mansour scheme. We present a new variant of the Even-Mansour scheme and introduce a variant of the Even-Mansour scheme. We focus on the security of these variants of the Even-Mansour scheme and present variation of the security according to key size. We prove the security of a variant of the Even-Mansour scheme and show that a generalized Even-Mansour scheme is not proper for a minimal block cipher.

• Journal of Information Processing Systems
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• v.11 no.4
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• pp.583-600
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• 2015

Generally, the wireless network provides priority to handover calls instead of new calls to maintain its quality of service (QoS). Because of this QoS provisioning, a call admission control (CAC) scheme is essential for the suitable management of limited radio resources of wireless networks to uphold different factors, such as new call blocking probability, handover call dropping probability, channel utilization, etc. Designing an optimal CAC scheme is still a challenging task due to having a number of considerable factors, such as new call blocking probability, handover call dropping probability, channel utilization, traffic rate, etc. Among existing CAC schemes such as, fixed guard band (FGB), fractional guard channel (FGC), limited fractional channel (LFC), and Uniform Fractional Channel (UFC), the LFC scheme is optimal considering the new call blocking and handover call dropping probability. However, this scheme does not consider channel utilization. In this paper, a CAC scheme, which is termed by a uniform fractional band (UFB) to overcome the limitations of existing schemes, is proposed. This scheme is oriented by priority and non-priority guard channels with a set of fractional channels instead of fractionizing the total channels like FGC and UFC schemes. These fractional channels in the UFB scheme accept new calls with a predefined uniform acceptance factor and assist the network in utilizing more channels. The mathematical models, operational benefits, and the limitations of existing CAC schemes are also discussed. Subsequently, we prepared a comparative study between the existing and proposed scheme in terms of the aforementioned QoS related factors. The numerical results we have obtained so far show that the proposed UFB scheme is an optimal CAC scheme in terms of QoS and resource utilization as compared to the existing schemes.

• Journal of Practical Engineering Education
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• v.12 no.2
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• pp.371-381
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• 2020

Most universities operate a mileage scheme that grants scholarships by converting students' extra-curricular activities into scores to encourage extra-curricular activities. This study seeks to understand the student experience of this mileage scheme, which universities are strategically providing to their students. For the purpose of the study, 16 students from universities where the mileage scheme is established were selected for in-depth interviews and the interview data was analyzed through consensual qualitative research methods. To secure the validity of research results, feedback was received from a reviewer regarding the appropriacy of areas and categories derived from the study. Ultimately, 3 areas of 'motivation behind participating in the mileage scheme', 'experience in the process of participating in the mileage scheme', 'impact of the experience after participating in the mileage scheme', and 18 categories were derived. This study is meaningful in that it focuses on the student experience of the university mileage scheme to present a review of the current university mileage scheme and suggest various implications for universities to consider when approaching the mileage scheme in the future.

• Journal of Korea Multimedia Society
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• v.19 no.2
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• pp.280-290
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• 2016

In this paper, we propose a layered pattern authentication scheme resistant to social engineering attacks. Existing android pattern lock scheme has some weak points for social engineering attacks. Thus, the proposed scheme improves the existing pattern lock scheme. In our scheme, pattern is recorded by touch screen, however, it is different with existing schemes because of the layered pattern. During the pattern registration process, users register their own pattern with many layers. Thus, registered pattern is 3D shape. When the smudge attack is occurring, the attacker can see the shape of user pattern through the smudge on smartphone screen. However, it is described on 2D surface, so acquired pattern is not fully determine to users original 3D shape. Therefore, our scheme is resistant to social engineering attack, especially smudge attack.

• ETRI Journal
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• v.37 no.2
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• pp.380-386
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• 2015

Guaranteeing quality of service over a multihop wireless network is difficult because end-to-end (ETE) delay is accumulated at each hop in a multihop flow. Recently, research has been conducted on network coding (NC) schemes as an alternative mechanism to significantly increase the utilization of valuable resources in multihop wireless networks. This paper proposes a new section-based joint NC and scheduling scheme that can reduce ETE delay and enhance resource efficiency in a multihop wireless network. Next, this paper derives the average ETE delay of the proposed scheme and simulates a TDMA network where the proposed scheme is deployed. Finally, this paper compares the performance of the proposed scheme with that of the conventional sequential scheduling scheme. From the performance analysis and simulation results, the proposed scheme gives more delay-and energy-efficient slot assignments even if the NC operation is applied, resulting in a use of fewer network resources and a reduction in ETE delay.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.1
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• pp.72-77
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• 2011

The checkpointing scheme is a well-known technique to cope with transient faults in digital systems. This paper proposes an adaptive checkpointing scheme for the reliability improvement of real-time control systems with concurrent fault detection capability. With concurrent fault detection capability the effect of transient faults are assumed to be detected with no latency. The proposed adaptive checkpointing scheme is based on the reliability analysis of an equidistant checkpointing scheme. Numerical data show the proposed adaptive scheme outperforms the equidistant scheme from a reliability point of view.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.9-12
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• 2000

A forward error correction (FEC) is usually used to correct the errors of the real-time data occurred at the reciever side which require a real-time transmission. The data transmission is peformed after being encapsulating by RTP and UDP. In the ITU-T study group 16, four FEC schemes using the XORing are presented. In the paper, a new supplementary scheme is proposed. In the delay problem the new scheme performs better than the scheme 3 but in the recovery ability for successive packet loss is worse than scheme 3. The proposed scheme which supplements the present schemes can be adapted easily to the current network environment.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.6
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• pp.413-424
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• 2017

In this paper, we show shortcomings of separate chaining scheme by way of experiments with NAND flash memory and improve the performance with merge chaining scheme which is proposed in this paper. We explain this merge chaining scheme and explain how to improve the performance of search operation. Merge chaining scheme shows better performance at insert and search operation compare to separate chaining scheme.

• ETRI Journal
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• v.30 no.5
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• pp.663-673
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• 2008

The multi-scenario topology of multi-channel hybrid ubiquitous sensor networks (USNs) is studied and a novel link auto-diversity cross-layer cooperative scheduling scheme is proposed in this paper. The proposed scheme integrates the attributes of the new performance evaluation link auto-diversity air-time metric and the topology space in the given multi-scenario. The proposed scheme is compared with other schemes, and its superiority is demonstrated through simulations. The simulation results show that relative energy consumption, link reception probability, and end-to-end blocking probability are improved. The addressing ratio of success with unchanged parameters and external information can be increased. The network can tolerate more hops to support reliable transportation when the proposed scheme is implemented. Moreover, the scheme can make the network stable. Therefore, the proposed scheme can enhance the average rate performance of the hybrid USN and stabilize the outage probability.