• The KIPS Transactions:PartD
• /
• v.9D no.4
• /
• pp.587-602
• /
• 2002

Replicated database system was emerged to resolve the problem of reduction of the availability and the reliability due to the communication failures and site errors generated at centralized database system. But if update transactions are many occurred, the update is equally executed for all replicated data. Therefore, there are many problems the same thing a message overhead generated by synchronization and the reduce of concurrency happened because of delaying the transaction. In this paper, I propose a new concurrency control algorithm for enhancing the degree of parallelism of the transaction in fully replicated database designed to improve the availability and the reliability. To improve the system performance in the replicated database should be performed the last operations in the submitted site of transactions and be independently executed update-only transactions composed of write-only transactions in all sites. I propose concurrency control method to maintain the consistency of the replicated database and reflect the result of update-only transactions in all sites. The superiority of the proposed method has been tested from the respondence and withdrawal rate. The results confirm the superiority of the proposed technique over classical correlation based method.

• Journal of Aerospace System Engineering
• /
• v.16 no.5
• /
• pp.62-69
• /
• 2022

EHA (Electro-Hydrostatic Actuator) is more energy efficiency than a centralized hydraulic system. In particular, the EHA used for aircraft has a redundant design in preparation for failure scenario. Also, due to the aircraft's internal space limitation, the actuator's length must be optimized. Therefore, a series configuration of double rod and single rod cylinder is advantageous. However, due to the asymmetry of the cross-sectional area of the piston, the force fighting phenomenon between the two cylinder areas occurs during redundant operation with a general control system. In this paper, the force fighting phenomenon of redundant EHA was simulated. A controller with load compensation and a force control-based position controller as a method to suppress its stimulation

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.21 no.4
• /
• pp.409-420
• /
• 2015

In this study, I researched, analysed and compared the examples of civilian maritime search and rescue auxiliaries of world leading countries' such as Japan and America, and the Korean volunteer fire fighting team. Through this, I suggest that the decentralized civilian maritime search and rescue forces of Maritime Rescue and Salvage Association and KCG Civilian Auxiliary should be united into unified search and rescue system and establish legal basis for stabilized support and development. It seem that we should organize laws and regulations for the government to have centralized control of rescue mission as in the cases of America and Canada and elivate rescue mission capability with systemized education and training entrusted to specialized external training organization. I proposed to establish financial support such as fund for the stabilized status of civilian auxiliary, domestic and overseas training session for the civilian auxiliary to inspire integrity and sense of duty as a part of maritime search and rescue forces.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.3
• /
• pp.81-88
• /
• 2020

The Renewable Portfolio Standard(RPS) which is in operated by country for many years is eco-friendly energy business. Although a variety of institute are accessing the RPS, it consists of a centralized system. Also, it shows opacity of data access in user's point of view. And each institutes is possessing their own data collected by themselves. Therefore decentralization and integrated control is demanded. Also, when institutes are attacked, the interruption of RPS can be existed. For resolving this issue, this study proposes the RPS using blockchain. Using the consortium method of blockchain, every institutes has possessing same data inserting REC data in block data, it is resolvable that transparency and security issue as transaction through verification of certain block. Furthermore, in case of one institute is paused by external attack, the role can be replaced by other institutes. This study tried the processing of putting data through ethereum network, therefore it presents the possibility of introducing the blockchain method in RPS.

• Proceedings of the Korea Database Society Conference
• /
• 1994.09a
• /
• pp.105-129
• /
• 1994

The information system of corporations are facing a new environment expressed by miniaturization, decentralization and Open System. It is therefore of utmost importance for corporations to adapt flexibly th such new environment by providing for corresponding changes to their existing information systems. The objectives of this study are to identify this new environment faced by today′s information system and develop effective methods for data resource management under this new environment. In this study, it is assumed that the new environment faced by information systems can be specified as Distributed Computing Environment, and in order to achieve such system, presents Client/server architecture as its representative computing structure, This study defines Client/server architecture as a computing architecture which specialize the fuctionality of the client system and the server system in order to have an application distribute and perform cooperative processing at the best platform. Furthermore, from among the five structures utilized in Client/server architecture for distribution and cooperative processing of application between server and client this study presents two different data management methods under the Client/server environment; one is "Remote Data Management Method" which uses file server or database server and. the other is "Distributed Data Management Method" using distributed database management system. The result of this study leads to the conclusion that in the client/server environment although distributed application is assumed, the data could become centralized (in the case of file server or database server) or decentralized (in the case of distributed database system) and the data management method through a distributed database system where complete responsibility and powers with respect to control of data used by the user are given not only is it more adaptable to modern flexible corporate environment, but in terms of system operation, it presents a more efficient data management alternative compared to existing data management methods in terms of cutting costs.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.3
• /
• pp.539-546
• /
• 2018

Recently, as the solar power generation market is rapidly increasing, interest is focused on research for minimizing the output of the solar cell module. The role of the power optimizer is important when inconsistencies occur in photovoltaic power generation. In the conventional system, centralized inverter method and microinverter method are mainly used. In this paper, we analyze the problem of power generation efficiency loss due to the incompatibility of existing system configuration methods. We also proposed a module - type power compensation method that can improve the mismatch caused by shading. The proposed module - based power optimizer is implemented and compared with the existing operation method. From the simulation result, it was confirmed that the efficiency of the proposed operation method is improved compared to the existing method.

• Health Policy and Management
• /
• v.1 no.1
• /
• pp.3-18
• /
• 1991

On the stage of transition from highly centralized government to local self-government in Korea, administrating practice characteristics of the directors of Health Centers is essentially required to be found. This study was conducted in order to find the administration patte군 of the directors of Health Centers in Korea and their opinion on the environment of health administration including personnel management regime for them. The materials were collected from 149 directors of Health Centers with a structured questionaire by mailing. The major findings of this study were as follows. 1. About two-thirds of the directors(69.1%) make plan through the consensus between public service perosonnel in programme department and them in budgt control department. And 75.0% of the directors maintain the planed by the predecessor. 2. More than two-thirds of the directors (71.1%) take subordinates opinion into consideration in case of the programmes facing objections. 3. When the directors face obstacles in pursuing health programmes they usually consult other public service personnel than inhabitants. 4. Only 10.8% of the directors were satisfied with the support of the Ministry of Internal Affairs for health administration while more than half of them were satisfied with the support of health institution in higher level. 5. The directors evaluated the job attitude of the public service personnel in low level as more favorable than that of there higher level public service personnel who work for central government. 6. Only 18.1% of the idrectors were satisfied with their saley. And more than half of them expect the promotion of their position. On the ground of this result the administration attitude of the directors of Health Centers would be evaluated as improved and as more positive than that of other public service personnel in health authorities. However, they are required to consult the inhabitants more frequently for health administration. An the public service personnel in high level who work for central government are required to improve their job attitude.

• KIISE Transactions on Computing Practices
• /
• v.23 no.5
• /
• pp.310-315
• /
• 2017

In a centralized control structure, the software defined network controller manages all openflow enabled switched in a data plane and controls the telecommunication between all hosts. In addition, the network manager can easily deploy the network function to the application layer with a software defined network controller. For this reason, many methods for network management using a software defined network concept have been proposed. The main policies for network management are related to traffic Quality of Service and resource management. In order to provide Quality of Service and load distribution for network users, we propose an efficient routing method using a naive bayesian algorithm and transmission delay estimation module. In this method, the forwarding path is decided by flow class and estimated transmission delay result in the software defined network controller. With this method, the load on the network node can be distributed to improve overall network performance. The network user also gets better dynamic Quality of Service.

• Journal of Satellite, Information and Communications
• /
• v.11 no.3
• /
• pp.37-42
• /
• 2016

In this paper, in today's highly complex video and broadcast operations, broadcasters are constantly challenged to reliably deliver low-latency, high-quality video to multiscreen audiences on-air and online. The Adaptive Bit Rate (ABR) protocols enable internet video to a wide range of multiscreen devices. However, video quality is often marginal and would prove unacceptable for valued linear broadcast content delivered to the Big Screen today. The Media information processing technology advances in ABR enables service providers to take control and offer quality managed linear video services to ALL screens in the home, including the Big Screen, with a single unified IP Video infrastructure. The New Multiscreen-Assisted ABR (MSA-ABR) delivery management system proposed using Cloud based multicast-assisted ABR for a broadcast facility that performs routing of contribution content and online publishing services within a virtual, centralized cloud infrastructure.

• Journal of Communications and Networks
• /
• v.11 no.1
• /
• pp.26-35
• /
• 2009

In this paper, we investigate how to do resource allocation to guarantee a minimum user data rate at low signaling overhead in multi-cell orthogonal frequency division multiple access (OFDMA) wireless systems. We devise dynamic resource allocation (DRA) algorithms that can minimize the QoS violation ratio (i.e., the ratio of the number of users who fail to get the requested data rate to the total number of users in the overall network). We assume an OFDMA system that allows dynamic control of frequency reuse factor (FRF) of each sub-carrier. The proposed DRA algorithms determine the FRFs of the sub-carriers and allocate them to the users adaptively based on inter-cell interference and load distribution. In order to reduce the signaling overhead, we adopt a hierarchical resource allocation architecture which divides the resource allocation decision into the inter-cell coordinator (ICC) and the base station (BS) levels. We limit the information available at the ICC only to the load of each cell, that is, the total number of sub-carriers required for supporting the data rate requirement of all the users. We then present the DRA with limited coordination (DRA-LC) algorithm where the ICC performs load-adaptive inter-cell resource allocation with the limited information while the BS performs intra-cell resource allocation with full information about its own cell. For performance comparison, we design a centralized algorithm called DRA with full coordination (DRA-FC). Simulation results reveal that the DRA-LC algorithm can perform close to the DRA-FC algorithm at very low signaling overhead. In addition, it turns out to improve the QoS performance of the cell-boundary users, and achieve a better fairness among neighboring cells under non-uniform load distribution.