• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.760-767
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• 2009

While network evolution toward all IP based wired and wireless converged network is on the move, services are being progressed into converged and complex services from simply coupled services, and telecommunication operators are developing new technologies which enable users to move between heterogeneous networks without discontinuity of a current service. In this paper, we propose a IP handover mechanism which reduces ping-pong effect during IP handover between WLAN and CDMA2000 1x EV-DO Rev.A neworks. We present stability and enhanced latency of the proposed IP handover mechanism by experimentation. The mechanism was developed under the 3rd phase of BcN project.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.487-497
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• 2010

In this paper, we propose a hard handover scheme which adaptively decides important handover parameters such as hysteresis and time-to-trigger values considering the load difference between the target and serving cells. First of all, the hysteresis value can be automatically adjusted according to the load difference, thus it is used to decide the handover trigger time. As a result, through the adaptive hysteresis scheme, handover drop rate is improved. However, this adaptive hysteresis scheme has a problem that the ping-pong effect, which occurs due to the frequent movement of mobile stations at the cell boundary, is increased. Therefore, to solve this problem, we propose a novel adaptive time-to-trigger scheme with the time-to-trigger which is in inverse proportion to the hysteresis value already established by the adaptive hysteresis scheme which adapts to the changing load difference between the target and serving cells. The simulation results show that the proposed adaptive time-to-trigger scheme based on the adaptive hysteresis is better than existing schemes in terms of handover drop rate and ping-pong generation.

• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.523-529
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• 2011

In this paper an inter-layer protocol, referred to as a Multi-Network Selector (MNS) is proposed for multiband maritime networks. A MNS is located between the data-link layer and the network layer and performs vertical handover when a ship moves another radio network. In order to provide seamless data transfer to different radio networks, the MNS uses received signal strength (RSS) and ship's location information as decision parameters for vertical handover, which can avoid ping-pong effect and reduces handover latency. In addition, we present related issues in order to implement the MNS for a multiband maritime network.

• International Journal of Contents
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• v.12 no.1
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• pp.54-59
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• 2016

The purpose of this paper is to discover how the use of digital applications can affect students' attitudes toward positive classroom participation and performance in learning a foreign language. Participants of this study were 128 students who took a foreign language class at a high school in central Korea. To find out students' perceptions and attitudes toward the effect of using a digital application for their foreign language study, online questionnaire and focus-group interview were conducted. Our research findings revealed that these students could engage in active language learning and experience learning improvement while studying a foreign language with digital applications. The improvement was possible by creating more interactive activities and quizzes. In addition, the digital application provided students immediate feedback. It gave students and teachers various motivations beyond the traditional 'chalk and talk' format of text-only-classes. This study provides an overview of the usefulness of digital application. In addition, it provides understanding for students' perceptions and involvement using digital application in a foreign language classroom.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1098-1105
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• 2007

Quantum mechanical and molecular dynamics simulation analysis has been performed on the model system for CALB (Candida antarctica lipase B) with esters to study the reaction mechanism and conformational preference of catalytic hydrolysis and the esterification reaction. Using quantum mechanical analysis, the ping-pong bi-bi mechanism was applied and energies and 3-dimensional binding configurations of the whole reaction pathways were calculated. Further molecular dynamics simulation analysis was performed on the basis of the transition state obtained from quantum mechanical study to observe the effect of structures of the substrates. Calculation results using substrates of different chain length and chiral configurations were compared for conformational preference. The calculated results showed very small influence on chain length, whereas chiral conformation showed big differences. Calculated results from molecular modeling studies have been compared qualitatively with the experimental data using racemic mixtures of (${\pm}$)-cis-4-acetamido-cyclopent-2-ene-1-ethyl acetate as substrates.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.163-170
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• 2007

The next generation communication environment consists of various wireless access networks with distinct features that are configured as an overlay topology. In the network environments, the frequency of hand overs should be minimized and the error propagation should be solved in order to provide high-quality multimedia services to mobile users. Therefore, we propose an performance enhancement approach, based on mSCTP, that provides high quality multimedia services to mobile users by ameliorating the error propagation problem. We utilizes the following four functions: 1) the separation of transmission paths according to the types of frames. 2) retransmission strategy to minimize the loss rate of frames, 3) Foced vertical handover execution by utilizing bicasting, 4) using the stability period in order to reduce the effect of the ping pong phenomenon. The simulation results show that the proposed approach provides seamless multimedia service to mobile users by achieving error resilience.

• The Journal of Korean Physical Therapy
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• v.25 no.2
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• pp.96-102
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• 2013

Purpose: The purpose of the study was to investigate the effect of a training program using virtual reality on the balance and lower muscular strength of Parkinson's disease patients. Methods: The study included 22 patients with Parkinson's disease who were arbitrarily classified into 2 groups: 11 patients in the experimental group and 11 patients in the control group. Balance was measured with the Berg balance scale (BBS), the functional reach test (FRT), one-leg stance test (OLST), and the timed up and go test (TUG); whereas, lower muscular strength was measured with the sit-to-stand test (STS). Ping-Pong, bowling, and tennis were selected for virtual reality training for the experimental group, and were performed for 30 minutes 3 times a week for 8 weeks. The control group did not undergo any of the virtual reality training programs. Results: A significant difference was observed in the BBS, FRT, OLST, TUG, and STS results within the experimental group that underwent the virtual reality training program. On the other hand, no significant difference was observed in the BBS, FRT, OLST, TUG, and STS values within the control groups. Conclusion: In conclusion, the virtual reality training program positively affects the balance and lower muscular strength in Parkinson's disease patients. This result indicates the possibility of application of the virtual reality training program to the management for Parkinson's disease patients, and highlights the need for the development and application of more efficient virtual reality training programs in the future.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.226-234
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• 2024

The frequent handover problem and playing ping-pong effects in 5G (5th Generation) ultra-dense networking cannot be effectively resolved by the conventional handover decision methods, which rely on the handover thresholds and measurement reports. For instance, millimetre-wave LANs, broadband remote association techniques, and 5G/6G organizations are instances of group of people yet to come frameworks that request greater security, lower idleness, and dependable principles and correspondence limit. One of the critical parts of 5G and 6G innovation is believed to be successful blockage the board. With further developed help quality, it empowers administrator to run many systems administration recreations on a solitary association. To guarantee load adjusting, forestall network cut disappointment, and give substitute cuts in case of blockage or cut frustration, a modern pursuing choices framework to deal with showing up network information is require. Our goal is to balance the strain on BSs while optimizing the value of the information that is transferred from satellites to BSs. Nevertheless, due to their irregular flight characteristic, some satellites frequently cannot establish a connection with Base Stations (BSs), which further complicates the joint satellite-BS connection and channel allocation. SF redistribution techniques based on Deep Reinforcement Learning (DRL) have been devised, taking into account the randomness of the data received by the terminal. In order to predict the best capacity improvements in the wireless instruments of 5G and 6G IoT networks, a hybrid algorithm for deep learning is being used in this study. To control the level of congestion within a 5G/6G network, the suggested approach is put into effect to a training set. With 0.933 accuracy and 0.067 miss rate, the suggested method produced encouraging results.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.370-381
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• 2005

Mobile IP provides an efficient and scalable mechanism for host mobility within the Internet. Using Mobile If, mobile nodes may change their point of attachment to the Internet without changing their If address. However, it would result in a high signaling cost. To reduce the signaling cost, we factor in the fact that mobile users will not be actively communicating much of the time. In fact, there Is no necessity to send a binding update message to the home agent when an mobile node does not communicates with others while moving. From this point of view, we propose a lazy update strategy for minimizing signaling cost using the forwarding pointer in hierarchical Mobile IPv6. In our proposal, binding updates are sent only when a mobile node is in a busy mode. If an mobile node is in a dormant mode, binding update messages are delayed until busy mode using the forwarding pointer. As a result, our proposal can reduce the total signaling cost by eliminating unnecessary binding update messages when a mobile node Is in a dormant mode. In addition to, our proposal reduces unnecessary location update cost resulting from ping-pong effect under mobile node's dormant mode. Analysis results using the discrete analytic model presented in this paper shows that our proposal can has superior performance than hierarchical Mobile nv6 when the call-to-mobility ratio is low and the length of the forwarding pointer chain K is low.