• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.149-155
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• 2003

This paper generally relates to the field of wireless local area networks(WLANs), and more particularly, to AP selection and association methods for the performance of a station. In these days, IEEE 802.11 Wireless LAN network is widely deployed and used as an emerging service to connect high-speed Internet in the public wireless environment. But, if there are many users in hot spot area, they suffer a severe decrease of performance. Thus it needs an association and access control mechanism especially when it is used in the public environment. In this paper, we suggest a selection and association method using Beacon or Probe Response frames based IEEE 802.11. Station selects AP using the information of the capacity area in a Beacon or a Probe Response frame. According to the present paper, an association method for a public WLAN service, which includes a WLAN user terminal and an AP for relaying WLAN communications to and from the user terminal, includes the steps of the user terminal asking the AP's states for access to a radio channel; and the station selects and associates with the AP. According to the above-described selection in a high speed wireless Internet service based on public WLAN technologies that are currently in operations. Further, it is possible to improve the efficiency of network management.

• The KIPS Transactions:PartA
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• v.11A no.1
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• pp.29-36
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• 2004

As the number of Internet users and the amount of web contents have increased very fast, reducing the load of web servers and providing web services more rapidly have been great issues. A web-cache system, which is located between the user and the web server, has been used by many web service providers as an effective way to reduce the load of web servers and the web service response time. In this paper, we have developed a web-cache system which is based on the Squid cache and has a compression capability. The web-cache system in which compression capability reduces the amount of network traffic and the web service response time by transfering the web contents in the compressed format over the network between the web-cache system and the user. The performance enhancement is greater in the reverse-cache system than in the forward-cache system because in the case of the reverse-cache system, the cache reduces the amount of traffic on the Internet which is the bottleneck in the network path between the user and the web server. The experimentation result shows that the amount of data traffic has reduced from 2 to 8 times depending on the size of the web contents. The web server response time has reduced 37% on the average and when the size of the web content is greater than 10Kbyte, the response time has reduced 87% on the average.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.180-194
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• 2017

Agricultural hazards management technology, which would allow individual farms to respond preemptively, has been developed. A preliminary system developed in the previous study provides precise weather forecasts by farms, notification of weather hazards by crops and delivery of response guidelines (http://www.agmet.kr). Although the GIS map-based alarm system has been implemented for a number of farmers and their farms, its user interface was not designed for individual users who seek information at their farms. In this study, we have developed a mobile application to provide early warnings of weather hazards up to 10 days in advance. A set of information including field-specific weather, crop growth stages and weather hazard alerts can be delivered to individual farmers through their mobile phone. This would guide users to access the map-based system using their smartphone to obtain field-specific weather information by the growth stage of cultivated crops. This would help the farmers make the better use of the existing weather-hazard GIS map-based alarm system.

• Journal of Internet Computing and Services
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• v.20 no.2
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• pp.39-49
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• 2019

Advances in IoT data analysis technology have made it easier to analyze situation and provide interactive services based on the context. Most of digital signage application have been used to provide information uni-directionally, but in the future it will evolve to provide personalized content according to the individual user situation and responses. However, it is not easy to modify or apply the existing interactive digital signage platforms due to their hardware dependency. The proposed platform is modularized by dividing main functions into two, the cloud and the edge, so that advertisement resources can be easily generated and registered. Thus, interactive advertisement can be rendered in a timely manner based on sensor analysis results. At the edge, personal data can be processed to minimize privacy issues, and real-time IoT sensor data can be analyzed for quick response to the signage player. The cloud is easier to access and manage by multiple users than edge. Therefore, the signage content generation module improves accessibility and flexibility by handling advertisement contents in the cloud so that multiple users can work together on the cloud platform. The proposed platform was developed and simulated in two aspects. First is the provider who provides the signage service, and second is the viewer who uses the content of the signage. Simulation results show that the proposed platform enables providers to quickly construct interactive signage contents and responses appropriately to the context changes in real-time.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.3
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• pp.73-82
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• 2022

Auto-scaling is one of the most important functions for cloud computing technology. Even if the number of users or service requests is explosively increased or decreased, system resources and service instances can be appropriately expanded or reduced to provide services suitable for the situation and it can improves stability and cost-effectiveness. However, since the policy is performed based on a single metric data at the time of monitoring a specific system resource, there is a problem that the service is already affected or the service instance that is actually needed cannot be managed in detail. To solve this problem, in this paper, we propose a method to predict system resource and service response time using a multivariate time series analysis model and establish an auto-scaling policy based on this. To verify this, implement it as a custom scheduler in the Kubernetes environment and compare it with the Kubernetes default auto-scaling method through experiments. The proposed method utilizes predictive data based on the impact between system resources and response time to preemptively execute auto-scaling for expected situations, thereby securing system stability and providing as much as necessary within the scope of not degrading service quality. It shows results that allow you to manage instances in detail.

• Journal of Intelligence and Information Systems
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• v.10 no.2
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• pp.111-131
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• 2004

Software change is an essential operation for software evolution. To maintain the system competently, managers as well as developers must be able to understand the structure of the system but the structure of software is hidden to the developers and managers who need to change it. In this paper, we present a system (OntCIA) for supporting change impact analysis for rating and billing domain based on the semantic web technology. The basic idea of OntCIA is to build a domain knowledge base using an OWL ontology and RDF to implement change impact analysis system that would support the managers and software developers in finding out information about structure of large software system. OntCIA allows users to incrementally build an ontology in rating and billing domain and provides useful information in response to user queries concerning the code, such as, for example 'Find the modules which have a role for confirming new subscription'. The strengths of OntCIA are its architecture for easy maintenance as well as semantic indexing by automatic reasoning.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.6
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• pp.2709-2734
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• 2020

The growing demand to make wireless data services 5G compatible has necessitated the development of an energy-efficient approach for an effective new wireless environment. In this paper, we first propose a cognitive sensor node (CSN) based game theory for deriving energy via a primary user-transmitted radio frequency signal. Cognitive users' time was segmented into three phases based on a time switching protocol: energy harvest, spectrum sensing and data transmission. The proposed model chooses the optimal energy-harvesting phase as the effected factor. We further propose a distributed energy-harvesting model as a utility function via pricing techniques. The model is a non-cooperative game where players can increase their net benefit in a selfish manner. Here, the price is described as a function pertaining to transmit power, which proves that the proposed energy harvest game includes Nash Equilibrium and is also unique. The best response algorithm is used to achieve the green connection between players. As a result, the results obtained from the proposed model and algorithm show the advantages as well as the effectiveness of the proposed study. Moreover, energy consumption was reduced significantly (12%) compared to the benchmark algorithm because the proposed algorithm succeeded in delivering energy in micro which is much better compared to previous studies. Considering the reduction and improvement in power consumption, we could say the proposed model is suitable for the next wireless environment represented in 5G.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.9-16
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• 2012

Though Android-based smart phones are being released in Korea, Korean TTS engine is not built on them and Google has not announced service or software developer's kit related to Korean TTS officially. Thus, application developers who want to include Korean TTS capability in their application have difficulties. In this paper, we design and implement Android OS-based Korean TTS system and service. For speed, text preprocessing and synthesis libraries are implemented using Android NDK. By using Java's thread mechanism and the AudioTrack class, the response time of TTS is minimized. For the test of implemented service, an application that reads incoming SMS is developed. The test shows that synthesized speech are generated in real-time for random sentences. By using the implemented Korean TTS service, Android application developers can transmit information easily through voice. Korean TTS service proposed and implemented in this paper overcomes shortcomings of the existing restrictive synthesis methods and provides the benefit for application developers and users.

• The KIPS Transactions:PartD
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• v.15D no.4
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• pp.549-556
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• 2008

Web-based Enterprise Intranet System is developed Object-oriented programming language and data management is constructed using RDBMS. Between Object-oriented programming language and RDBMS bring about "Object-Relational Impedance Mismatch" due to heterogeneous paradigm. To solve this kinds of problems commonly use the ORM Framework that it is converting data between incompatible type systems in databases and object-oriented programming languages, uses complex mapping metadata. It causes difficult to develop and maintain because of inflexible in changes. This paper proposed persistence framework that solve the existing complexity of ORM framework and has more flexible in evolution of database table. This persistence framework is unnecessary meta information that connecting with entity of database table and the objects, it offers users convenience of maintenance and it allows far more flexible and affordable systems to be built because of automatically code generation. The result of testing based on the proposed persistence framework with Hibernate, iBATIS, It is similar response time with iBATIS and it has more about three times faster than Hibernate. But iBATIS has problems of mass data processing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4583-4591
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• 2010

Existing XML-based variable data publishing, in which a user has to manually prepare and edit template rules, is rather difficult for general users to create documents. Especially when processing large variable XML documents such as manuals or technical documents, fast document formatting is required to provide fast response speed for editing, which the existing batch processing cannot provide. This paper proposes a variable data publishing system with dynamic editing and formatting function, which support fast formatting upon user's request for large volume documents as well as for template editing through interaction by displaying the result of template-based variable documents on WYSIWYG screen. Proposed system can be effectively used for creating customized documents with many variable data that can be changed according to individual characteristics such as individual, company or area; source documents, template documents and formatted documents adopt XML, XSLT and XPath standards suggested by W3C, which facilitates extension to web document processing system.