• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.195-215
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• 2021

Multipath Transport Control Protocol (MPTCP) is a transport layer protocol that enables multiple TCP connections across various paths. Due to path heterogeneity, it incurs more energy in a multipath wireless network. Recent work presents a set of approaches described in the literature to support systems for energy consumption in terms of their performance, objectives and address issues based on their design goals. The existing solutions mainly focused on the primary system model but did not discourse the overall system performance. Therefore, this paper capitalized a novel stochastically multipath scheduling scheme for data and path capacity variations. The scheduling problem formulated over MPTCP as a stochastic optimization, whose objective is to maximize the average throughput, avoid network congestion, and makes the system more stable with greater energy efficiency. To design an online algorithm that solves the formulated problem over the time slots by considering its mindrift-plus penalty form. The proposed solution was examined under extensive simulations to evaluate the anticipated stochastic optimized MPTCP (so-MPTCP) outcome and compared it with the base MPTCP and the energy-efficient MPTCP (eMPTCP) protocols. Simulation results justify the proposed algorithm's credibility by achieving remarkable improvements, higher throughput, reduced energy costs, and lower-end to end delay.

• Korean Journal of Construction Engineering and Management
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• v.19 no.2
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• pp.61-72
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• 2018

Conflicts in public construction projects lead to increase social costs as well as construction costs and schedule delay. Therefore, it is important to evaluate the conflict in construction project and find appropriate solutions based on previous cases. In this research, the conflict factors and criteria for evaluating conflict are derived and 30 cases are evaluated by 11 conflict experts. Using k-means clustering, the cases are clustered by three clusters. The cases were analyzed according to the characteristics of each cluster and labeled as 'NIMBY and harmful facility conflict cluster', 'environmental and pollution conflict cluster', and 'PIMFY and small conflicts'. In the future, when conflict occurs in the public construction projects, the conflict can be evaluated using this clustering and the characteristics of the conflicts can be found. As a result, it will be helpful to mitigate the conflict quickly and effectively by looking for previous cases that are suitable for resolving the conflict through appropriate clusters.

• Journal of Communications and Networks
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• v.11 no.6
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• pp.574-588
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• 2009

Although much research has been conducted in the area of authentication in wireless networks, vehicular ad-hoc networks (VANETs) pose unique challenges, such as real-time constraints, processing limitations, memory constraints, frequently changing senders, requirements for interoperability with existing standards, extensibility and flexibility for future requirements, etc. No currently proposed technique addresses all of the requirements for message and entity authentication in VANETs. After analyzing the requirements for viable VANET message authentication, we propose a modified version of TESLA, TESLA++, which provides the same computationally efficient broadcast authentication as TESLA with reduced memory requirements. To address the range of needs within VANETs we propose a new hybrid authentication mechanism, VANET authentication using signatures and TESLA++ (VAST), that combines the advantages of ECDSA signatures and TESLA++. Elliptic curve digital signature algorithm (ECDSA) signatures provide fast authentication and non-repudiation, but are computationally expensive. TESLA++ prevents memory and computation-based denial of service attacks. We analyze the security of our mechanism and simulate VAST in realistic highway conditions under varying network and vehicular traffic scenarios. Simulation results show that VAST outperforms either signatures or TESLA on its own. Even under heavy loads VAST is able to authenticate 100% of the received messages within 107ms. VANETs use certificates to achieve entity authentication (i.e., validate senders). To reduce certificate bandwidth usage, we use Hu et al.'s strategy of broadcasting certificates at fixed intervals, independent of the arrival of new entities. We propose a new certificate verification strategy that prevents denial of service attacks while requiring zero additional sender overhead. Our analysis shows that these solutions introduce a small delay, but still allow drivers in a worst case scenario over 3 seconds to respond to a dangerous situation.

• The Journal of Bigdata
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• v.9 no.1
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• pp.141-152
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• 2024

In the biopharmaceutical contract manufacturing organization (CMO) business, establishing a production schedule that satisfies the due date for various customer orders is crucial for competitiveness. In a CMO process, each order consists of multiple batches that can be allocated to multiple production lines in small batch units for parallel production. This study proposes a meta-heuristic algorithm to establish a scheduling plan that minimizes the total delivery delay of orders in a CMO process with identical parallel machine. Inspired by biological evolution, the proposed algorithm generates random data structures similar to chromosomes to solve specific problems and effectively explores various solutions through operations such as crossover and mutation. Based on real-world data provided by a domestic CMO company, computer experiments were conducted to verify that the proposed algorithm produces superior scheduling plans compared to expert algorithms used by the company and commercial optimization packages, within a reasonable computation time.

• Journal of Biomedical Engineering Research
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• v.38 no.6
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• pp.308-312
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• 2017

Skeletal muscle function plays a very important role in quality of life. However, skeletal muscle causes functional decline under aging or some diseases. Exercise and muscle training are good solutions to delay sarcopenia, but there are limitations to those who are uncomfortable in exercise. For this reason, alternative interventions for muscle sarcopenia are required, and many studies proved the increase of skeletal muscle mass by electrical stimulation. In conventional studies, however, mouse skeletal muscle cells have been mostly used in experiments to identify electrical stimulation conditions while human derived cells have not been frequently utilized in these studies. Stimulation used for rehabilitation has been uniformly treated without the consideration of aging. In addition, many studies have been used with conventional petri dish usually requiring many numbers of cells, which is not appropriate for rare. Moreover, they are not usually condition uniformity of electrical field. In this study, we have developed an electrical stimulation device which consumes a small amount of cells and can form a uniform electrical field. With the system, we analyzed the skeletal muscle differentiation and Myotube thickness depending on the electrical stimulation condition.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.29-36
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• 2007

IP paging strategy, one of the solutions for derived problems in IP mobility support protocol, reduces the messages and the overheads over the network, since there is not registration procedure when a mobile terminal moves into a new router within the same paging area. However, the fact that the mobile terminals with the previous strategy consume electrical power continuously for paging signal reception obstructs the application of IP paging strategy to the IP-based wireless sensor networks. In this paper, we propose a discontinuous paging reception strategy based on the characteristics of the wireless sensor networks and their mobile terminals. As a result of the mathematical analysis, the proposed strategy significantly reduces the terminals' power consumption. In addition, by setting the relating parameters as appropriate values, the proposed strategy can be switched to the continuous reception strategy, or can be adjusted to limit the terminals' power consumption or paging delay.

• Korea Trade Review
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• v.42 no.5
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• pp.233-252
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• 2017

The fast changes of global financial environment in recent years increase the risk of trade settlement. This means are required to minimize risk of non payment and to maximize secure payment. Open Account trade accounts for 90% of global trade flows. The O/A system means that the goods, along with all the necessary documents, are shipped and delivered before payment is due, usually within a time frame from 30 to 90 days. Meanwhile, Korean small and medium-sized export enterprises are compelled to globalize their activities owing to limitation and competitiveness of domestic marketplace. To keep face with the global trade settlement system and to support globalization of small and medium-sized export firms, the BPO together with Supply Chain Finance will be solutions. The introduction of the BPO system will allow banks to broaden O/A offerings to their client base and due to secure safety, sellers could ship the goods without delay according to orders and buyers could settle promptly by payment undertaking of correspondent banks. Therefore, it is more effective for companies which have sustainable customers and stable transaction. This study take a look at the trend of the global payment systems and suggested limitation of existed payment in order to derive improvement measures of electronic payment for small and medium-sized export enterprises.

• The Journal of the Korea Contents Association
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• v.12 no.4
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• pp.10-19
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• 2012

Seamless streaming of multimedia content that ensures Quality of Service over heterogeneous networks has been a desire for many multimedia services, for which the multimedia contents should be adapted to usage environments such as network characteristics, terminal capabilities, and user preferences. Scalability in video coding is a good feature to meet the requirement of heterogeneous networks. In this paper, we propose a dynamic adaptation scheme of H.264/AVC SVC bit-stream using the MPEG-21 Digital Item Adaptation (DIA) tool. MPEG-21 DIA framework provides systematic solutions in choosing an adaptation operation to given conditions and supports interoperable video adaptation. The experiment results show that the proposed adaptation scheme provides QoS-enabled delivery and consumption of SVC with time-varying constraints of network, terminal, and user preference, in a robust and efficient way. In particular, the proposed adaptation scheme is proved to work well with very low delay under the condition that the variation rate of the given network bandwidth is upto 62%.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.145-145
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• 2022

Availability of abundant water resources data in developing countries is a great concern that has hindered the adoption of deep learning techniques (DL) for disaster prevention and mitigation. On the contrary, over the last two decades, a sizeable amount of DL publication in disaster management emanated from developed countries with efficient data management systems. To understand the current state of DL adoption for solving water-related disaster management in developing countries, an extensive bibliometric review coupled with a theory-based analysis of related research documents is conducted from 2003 - 2022 using Web of Science, Scopus, VOSviewer software and PRISMA model. Results show that four major disasters - pluvial / fluvial flooding, land subsidence, drought and snow avalanche are the most prevalent. Also, recurrent flash floods and landslides caused by irregular rainfall pattern, abundant freshwater and mountainous terrains made India the only developing country with an impressive DL adoption rate of 50% publication count, thereby setting the pace for other developing countries. Further analysis indicates that economically-disadvantaged countries will experience a delay in DL implementation based on their Human Development Index (HDI) because DL implementation is capital-intensive. COVID-19 among other factors is identified as a driver of DL. Although, the Long Short Term Model (LSTM) model is the most frequently used, but optimal model performance is not limited to a certain model. Each DL model performs based on defined modelling objectives. Furthermore, effect of input data size shows no clear relationship with model performance while final model deployment in solving disaster problems in real-life scenarios is lacking. Therefore, data augmentation and transfer learning are recommended to solve data management problems. Intensive research, training, innovation, deployment using cheap web-based servers, APIs and nature-based solutions are encouraged to enhance disaster preparedness.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.6 s.312
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• pp.1-8
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• 2006

Many researches on path planning and obstacle avoidance for the fundamentals of mobile robot have been done recently. Informations from various sensors can be used to find obstacles and plan feasible path. In spite of many solutions of finding optimal path, each can be applied in only a constrained condition. This means that it is difficult to find university good algorithm. An optimal path with a complicated computation generates a time delay which cannot avoid moving obstacles. In this paper, we propose an algorithm of path planning and obstacle avoidance for mobile robot. We call the proposed method Random Access Sequence(RAS) method. In the proposed method, a small region is set first and numbers are assigned to its neighbors, then the path is selected using these numbers and cumulative numbers. It has an advantage of fast planning time and completeness of path if one exists. This means that new path selection may be possible within short time and that helps a robot to avoid obstacle in dynamic environments. Using the information of the start and destination position, the RAS can be performed for collision-free navigation by reforming feasible paths repeatedly in dynamic environments.