• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.113-122
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• 2020

In this paper, we propose the terminal authentication system using blockchain and TOTP(Time-based One-time Password Algorithm) to sustain a continuous authentication between user device and service device. And we experiment this system by using door-lock as a terminal of IoT(Internet of Things). In the future, we can apply this result to several devices of IoT for convenience and security. Although IoT devices frequently used everyday require convenience and security at the same time, it is difficult for IoT devices having features of the low-capacity and light-weight to apply the existing authentication technology requiring a high amount of computation. Blockchain technology having security and integrity have been used as a storage platform, but its authentication cannot be performed when the terminal cannot access any network. We show the method to solve this problem using Blockchain and TOPT.

• Informatization Policy
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• v.21 no.1
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• pp.35-56
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• 2014

Information and communication technologies(ICT) allow and force people to work anywhere, anytime using remote databases and application systems available in real-time twenty four hours a day and seven days a week. With the real time nature of ICT, individual work is becoming more and more fragmented. Instead of working on a similar task repeatedly, individuals are required to respond to e-mails and inquiries through social networks, work on planning documents, work on presentation documents, work on spreadsheets, input necessary data on company databases, generate necessary reports from the database, run teleconference, etc., all maybe in a day's work. Work fragmentation may impact negatively on productivity as the flow is interrupted, but it may increase the productivity by allowing people to handle multiple tasks in a shorter time period. This study explores the types of work fragmentation and their characteristics. An online survey was administered to collect data about work fragmentation and work characteristics including autonomy, complexity, flexibility, usage of ICT, etc. 300 cases were used in the analysis. Analysis of k-mean cluster indicated four different types of work fragmentation: concentrated, temporally distributed, spatially distributed, and fully fragmented.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.41-48
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• 2011

Wireless communication technology developed, portable wireless devices based on wireless network including the smartphone rapidly developed, and products with functions similar to highly efficient computer are being launched. Therefore, active studies to enable performance of works, which were previously held in computers, on portable wireless terminal are being held. Until now, simulation was undertaken using computers which satisfy high performance computing resource. Such contains a problem that it cannot break away the limit of space. Portable wireless terminal has the merit that it can break away from the limit of space by using wireless network in comparison to wired environment. In this paper, it suggests a simulator based on wireless devices for distributed simulation. For such purpose, the performance time of simulation will be compared in regards to the case of performing nodes control simulation in a single highly efficient computer and the case of performing distributed simulation in many wired and wireless network environments. Through the comparison, the possibility for utility of portable wireless terminal as the object of distributed simulation will be verified, and it will be presented that simulation can be performed in a shorter time by performing distributed simulation under various wired and wireless network environments away from the limit of space.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.1139-1145
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• 2014

In shipyard site, a ship is constructed by integrating lots of modules that are made in several sites with different capabilities and specifications. Recently, it needs to make a shipyard to be smart communicating various multimedia information with wired and wireless broadband networks between hierarchical shipyards. In this paper, we propose an additional function of an LTE femtocell local gateway at a remote shipyard, an information exchange method between hierarchical shipyards, and an offload method to separate the general traffic. To reduce traffic of duplicated requests in shipyard, we apply a D2D communication scheme for supporting communication between shipyard equipments without IP service network. Hence, it is expected to increase the productivity of shipyard industry with mobile communications, D2D and broadband Internet technologies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.178-188
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• 2016

The traffic in the wired and wireless networks has increased exponentially because of increase of smart phone and improvement of PC performance. Multimedia services and file transmission such as Facebook, Youtube occupy a large part of the traffic. CDN is a technique that duplicates the contents on a remote web server of content provider to local CDN servers near clients and chooses the optimal CDN server for providing the content to the client in the event of a content request. In this paper, the content request message between CDN servers and the client used the SCRP algorithm utilizing the MST algorithm and the traffic throughput was optimized. The average response time for the content request is reduced by employing HC_LRU cache algorithm that improves the cache hit ratio. The proposed SCRP and HC_LRU algorithm may build a scalable content delivery network system that efficiently utilizes network resources, achieves traffic localization and prevents bottlenecks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.348-357
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• 2012

Recently, smartphone, notebook, PC and other supporting wireless LAN device have come into wide use. By increasing user that use wireless LAN device, wireless traffic also increased. If wireless traffic through one AP is increase, it causes throughput decrease. To solve this problem, wireless LAN service provider install more AP where overload occurred. But this is not enough. Because stations can't know AP's load factor, and APs do nothing for load balancing. In this paper, we propose Multi-Interface Access Point(MIAP) to solve this problem. MIAP operate same as multiple APs with multi-interface, and MIAP measure each interface's load periodically. If MIAP detect overloaded interface, MIAP transfer station from overloaded interface to under-loaded interface. We conducted an experiment for verifying existing problem, and we found this problem occurred. We plan an experiment scenario for a comparison between existing AP and MIAP, and excute these experiment. In the result, we show MIAP with load balancing can improve total throughput about 72% and stabilize delay jitter than existing AP.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1222-1229
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• 2012

For the reduction of electric energy consumption and its efficient use at homes or buildings, a new work item proposal for new architecture and functional requirements of Energy Saving System (ESS) was proposed to IEC TC 100 and accepted as a new project, IEC PT 62654 in 2009. Recently, the final ballot for publication passed without negative votes and IEC TS 62654 was finally published in August 2012. For the verification of this standard, Prototype of ESS system composed of an ESS server, ESS clients, and portable ESS terminal were especially implemented in parallel with the standardization. Electric Power Control and Management (EPCM) protocol for the communication between ESS server and clients was also implemented, which supports self-configuration of ESS network, power consumption monitoring, remote power control, and additional functions for intelligent energy saving services.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.72-77
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• 2011

Spectrum sensing is a critical functionality of CR network; it allow secondary user to detect spectral holes and to opportunistically use under-utilized frequency bands without causing harmful interference to primary use. Recently, wideband service has been increase for processing abundance of data traffic. So CR network needs a realizable implementation design of spectrum sensing for wideband. To get high resolution performance of wideband sensing must precede algorithm processing for reliability signal detection. By the way, the performance of spectrum sensing can be degraded due to fading and shadowing. In order to overcome this problem, we propose system model of wideband sensing scheme on energy detected collaborative technique. we divide wideband into narrowbands and use narrowbands to detect signal excepting some narrowbands including bad channel through the CSI. And we simulate and analyze in terms of detection probability with various SNR.

• Journal of Information Technology and Architecture
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• v.11 no.2
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• pp.143-155
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• 2014

In recent years, domestic electronics, banking, electricity, services, manufacturing, pharmaceutical, corporate type and malicious hackers is corporate security through the accident occurred and the resulting loss of corporate information and the damage each year is steadily increasing. Many companies have responded to domestic business activities and to protect critical information related to laptops, smart phones, tablets, and introduced a variety of Endpoint security solutions within. However, being introduced to senselessly Endpoint security solution across the over-budget, with the same features and performance, such as conflicts and problems arise, resulting in additional maintenance costs, in an effort to resolve the conflict in the operational security of the IT department's new difficulty in becoming. Here is the introduction and operation of these Endpoint security solutions in order to solve the problem on employees's PC into the center of the information security governance based on Endpoint security solution to provide the process for determining the solutions presented.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1491-1498
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• 2017

As the use of smartphones and the launch of various apps have increased rapidly, the number of malicious apps has also increased, and the damage is continuing. The Google Market where Android apps are registered is inevitably present at the same time as normal apps and malicious apps even though there are regulations for app registration. Especially, as social networks are activated, users are connected with social networks, and the ratings, downloads and awareness information are reflected in the number of downloaded apps. As a result, when users choose their apps by simply reflecting ratings, popularity, popular comments, and highly-categorized apps, malicious app downloads can sometimes cause significant harm. Therefore, this study first analyzed the tendency of malicious apps by directly crawling and analyzing long-term social information in the currently active Android market.