• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.243-246
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• 2002

In this paper, an advanced load balancing algorithm in nth order Hypercube distributed system has been proposed. The new algorithm uses centralized load-balancing to avoid blocking phenomenon and processor thrashing, and shows the results which makes loads to approach average value of loads. The new algorithm os compared with several other algorithm and it shows a merit in cost function value.

• Journal of the Korea Society for Simulation
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• v.16 no.4
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• pp.77-86
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• 2007

Web services are considered as the critical component in the business plans of corporations as they offers the potential for creating highly dynamic and versatile distributed applications that span across business boundaries. Web Service Orchestration studies composition of already-existing web services to create new value-added services. The composite web services could be executed in a centralized or peer-to-peer(P2P) orchestration model. Compared with centralized-orchestration model, the P2P-based orchestration model provides better scalability, reliability, and performance for the overall services. However, recent P2P-orchestration solutions have limitation in supporting complex workflow patterns. Therefore, they could not effectively handle sophisticated business workflow, which contains complex workflow patterns. In this paper, we propose the WORKGLOW system, which can deal with complex workflow patterns while it is able to perform composite services in P2P orchestration manner. Comparing with centralized orchestration systems, the WORKGLOW brings up more business logic advantages, better performance, and higher flexibility with only a little overhead.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.3
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• pp.958-979
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• 2023

Due to laws, regulations, privacy, etc., between 70-90 percent of providers do not share medical data, forming a "data island". It is essential to collaborate across multiple institutions without sharing patient data. Most existing methods adopt distributed learning and centralized federal architecture to solve this problem, but there are problems of resource heterogeneity and data heterogeneity in the practical application process. This paper proposes a collaborative deep learning modelling method based on the blockchain network. The training process uses encryption parameters to replace the original remote source data transmission to protect privacy. Hyperledger Fabric blockchain is adopted to realize that the parties are not restricted by the third-party authoritative verification end. To a certain extent, the distrust and single point of failure caused by the centralized system are avoided. The aggregation algorithm uses the FedProx algorithm to solve the problem of device heterogeneity and data heterogeneity. The experiments show that the maximum improvement of segmentation accuracy in the collaborative training mode proposed in this paper is 11.179% compared to local training. In the sequential training mode, the average accuracy improvement is greater than 7%. In the parallel training mode, the average accuracy improvement is greater than 8%. The experimental results show that the model proposed in this paper can solve the current problem of centralized modelling of multicenter data. In particular, it provides ideas to solve privacy protection and break "data silos", and protects all data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.315-321
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• 2010

In Ad-hoc networks, centralized power control is not suitable due to the absence of base stations, which perform the power control operation in the network to optimize the system performance. Therefore, each node should perform power control algorithm distributedly instead of the centralized one. The conventional distributed power control algorithm does not consider the adaptive bit loading operation to change the MCS (modulation and coding scheme) according to the received SINR (signal to interference and noise ratio), which limits the system throughput. In this paper, we propose a novel distributed bit loading and power control algorithm, which considers the adaptive bit loading operation to increase total system throughput and decrease outage probability. Simulation results show that the proposed algorithm performs much better than the conventional algorithm.

• Convergence Security Journal
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• v.24 no.2
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• pp.141-150
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• 2024

With the increasing frequency of incidents related to personal information leaks, there is a growing concern about personal information protection. Moreover, with the emergence of blockchain technology, there is a heightened interest in self-sovereign identity models applied through blockchain, with ongoing research on Decentralized Identifiers (DID) to achieve this. However, despite universities storing and utilizing significant information such as personal data, their computer systems are operated and managed based on centralized systems, leading to annual occurrences of personal data breaches. Therefore, this paper proposes and implements a DID-based computing system applicable within universities. Additionally, it establishes and executes prominent services within the university context. The proposed system ensures users' self-sovereign identities through verifiable credentials, enabling the establishment of a secure integrated information system within the university, departing from traditional centralized systems.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.10
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• pp.983-990
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• 2008

This paper presents the fault detection and diagnosis(FDD) algorithm to enhance reliability of a longitudinal controller for an autonomous All-Terrain Vehicle(ATV). The FDD is designed to monitor and identify faults which may occur in distributed hardware used for longitudinal control, e.g., DSPs, CAN, sensors, and actuators. The proposed FDD is an integrated approach of decentralized and centralized FDD. While the former is processed in a DSP and suitable to detect faults in a single hardware, it is sensitive to noise and disturbance. On the other hand, the latter is performed via communication and it detects and diagnoses faults through analyzing concurrent performances of multiple hardware modules, but it is limited to isolate faults specifically in terms of components in the single hardware. To compensate for disadvantages of each FDD approach, two layered structure including both decentralized and centralized FDD is proposed and it allows us to make more robust fault detection and more specific fault isolation. The effectiveness of the proposed method will be validated experimentally.

• Journal of Radiation Protection and Research
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• v.34 no.1
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• pp.1-7
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• 2009

It is expected that a substantial amount of spent fuels will be transported from the four nuclear power plant (NPP) sites in Korea to a hypothetical centralized interim storage facility or a final repository in the near future. The cost for the transportation is proportional to the amount of spent fuels. In this paper, a cost estimation program is developed based on the conceptual design of a transportation system and a logistics analysis. Using the developed computer program, named as CASK, the minimum capacity of a centralized interim storage facility (CISF) and the transportation cost for PWR spent fuels are calculated. The PWR spent fuels are transported from 4 NPP sites to a final repository (FR) via the CISF. Since NPP sites and the CISF are located along the coast, a sea-transportation is considered and a road-transportation is considered between the CISF and the FR. The result shows that the minimum capacity of the interim storage facility is 15,000 MTU.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.643-651
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• 1996

In this paper, to provide the possibility of various multimedia services, especially the collaborative work using the centralized control feature of the Service Node, is studied. We focused on the telewriting as the upper layer application to confirm the basic functions of the collaborative work. For this, we implement and add telewriting collaborative work function to the Service Node emulator, and terminals operating in the Windows environment are also developed. Through the tests on the system, we verify the basic functions related to the collaborative work are performed adequately, and confirm the concept of Service Node can support various type of multimedia conference services.

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.559-564
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• 2010

This paper proposes an advanced filter design to improve power quality of a head electric power (HEP) as a power conversion unit in centralized-power type electric railway vehicle. First of all, we have measured waveform of output power of transformer connected HEP to design the filter. Throughout experiment and simulation results, it is estimated that switching technique used HEP is advanced selected harmonic elimination PWM (SHEPWM) and the applied switching frequency is about 300Hz. In this paper, a filter to improve power quality considering estimated parameters is designed. As a result, the reduction of the magnitude of the overall harmonic is achieved and confirmed through simulations.

• ETRI Journal
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• v.29 no.5
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• pp.545-558
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• 2007

This paper presents an efficient semantic service discovery scheme called UbiSearch for a large-scale ubiquitous computing environment. A semantic service discovery network in the semantic vector space is proposed where services that are semantically close to each other are mapped to nearby positions so that the similar services are registered in a cluster of resolvers. Using this mapping technique, the search space for a query is efficiently confined within a minimized cluster region while maintaining high accuracy in comparison to the centralized scheme. The proposed semantic service discovery network provides a number of novel features to evenly distribute service indexes to the resolvers and reduce the number of resolvers to visit. Our simulation study shows that UbiSearch provides good semantic searchability as compared to the centralized indexing system. At the same time, it supports scalable semantic queries with low communication overhead, balanced load distribution among resolvers for service registration and query processing, and personalized semantic matching.