• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.1004-1009
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• 2004

Precise time synchronization is a main technology in high-speed communications, parallel and distributed processing systems, Internet information industry and electronic commerce. Synchronized clocks are useful for many leasers. Often a distributed system is designed to realize some synchronized behavior, especially in real-time processing in factories, aircraft, space vehicles, and military applications. Nowadays, time synchronization has been compulsory thing as distributed processing and network operations are generalized. A network time server obtains, keeps accurate and precise time by synchronizing its local clock to standard reference time source and distributes time information through standard time synchronization protocol. This paper describes design issues and implementation of a network time server for time synchronization especially based on a clock model. The system uses GPS (Global Positioning System) as a standard reference time source and offers UTC (universal Time coordinated) through NTP (Network Time protocol). Implementation result and performance analysis are also presented.

• The KIPS Transactions:PartA
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• v.13A no.7 s.104
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• pp.561-572
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• 2006

Performance of the mobile devices greatly depends on the efficient resource management because they are usually resource-restricted. In particular, the dynamic storage allocation algorithms very important part of the mobile device's operating system and OS-like software platform. The existing dynamic storage allocation algorithms did not consider application's execution style and the type, life-time, and characteristics of memory objects that the application uses. Those algorithms, as a result, could not manage memory efficiently Therefore, this Paper analyzes the mobile application's execution characteristics and proposes anew dynamic storage allocation algorithm which saves the memory space and improves mobile application's execution speed. The test result shows that the proposed algorithm works 6.5 times faster than the linked-list algorithm[11], 2.5 times faster better than the Doug. Lea's algorithm[12] and 10.5 times faster than the Brent algorithm[14].

• The KIPS Transactions:PartB
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• v.16B no.5
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• pp.427-434
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• 2009

With the rapid evolution of the Internet and mobile environments, text including spelling errors such as newly-coined words and abbreviated words are widely used. These spelling errors make it difficult to develop NLP (natural language processing) applications because they decrease the readability of texts. To resolve this problem, we propose a spelling error correction model using a spelling error correction dictionary and a newspaper corpus. The proposed model has the advantage that the cost of data construction are not high because it uses a newspaper corpus, which we can easily obtain, as a training corpus. In addition, the proposed model has an advantage that additional external modules such as a morphological analyzer and a word-spacing error correction system are not required because it uses a simple string matching method based on a correction dictionary. In the experiments with a newspaper corpus and a short message corpus collected from real mobile phones, the proposed model has been shown good performances (a miss-correction rate of 7.3%, a F1-measure of 97.3%, and a false positive rate of 1.1%) in the various evaluation measures.

• The Journal of Society for e-Business Studies
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• v.20 no.2
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• pp.93-106
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• 2015

Providing trading partners with personal information to establish an e-commerce financial transaction is inevitable. Most e-commerce companies keep personal information and transaction data for user's convenience and develop additional services as their applications. However, keeping personal information increases the likelihood of identity theft causing direct or indirect damage while it may simplify repetitive financial transactions. This study introduces risk management methods based on quantitative and qualitative analysis including demand-supply curve model and Gordon & Loeb model to analyze the risks for security management. The empirical analysis with survey results from KISA (Korea Information Security Agency) shows that the root cause of different statistics of personal information leakage incidents according to core business of internet companies is the difference in their Loss Expectancy caused by them. Also we suggest disciplinary compensation and higher standard for personal information protection as a solution to prevent the variation of investment on it between individual companies.

• Convergence Security Journal
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• v.15 no.2
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• pp.11-17
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• 2015

According to NIA (National Information Society Agency) report, digital divide is a vicious circle which makes quality interval of human's life between people who have information and relatively not. Especially in a smart phone society, there is a big problem between disabled people and normal people. This paper suggests a braille keyboard system for the blind to solve these problems. It is designed for portable use, convenience and quick text typing based on bluetooth communication technique. In text input test, all texts (Korean, English, number) were accurately expressed and typing speed was about 22 [c/m](characters per a minute). Especially, we design text2voice function to provide more accurate key input system. Popular applications such as call, alarm, message, kakao talk, internet, music, were performed without carring problems using the proposed braille keyboard system. The proposed technique is thought to contribute to eliminating the digital divide through the expansion of smartphone users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.1-12
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• 2002

In the multimedia CDMA mobile communication service, it is required to support various applications, such as voice, video, file transfer, e-mail, and Internet access, with guaranteed QoS. In the mixed traffic environment ,which consists of voice, stream data, and packet data, we analyze the network where preemptive priority is granted to delay-intolerant voice service and a buffer is offered to delay-tolerant stream data service. And, for best-effort packet data service, the access control by transmission permission probability is applied to obtain prominent throughput. To analyze the multimedia CDMA mobile communication system, we build a 2-dimensional markov chain model about prioritized-voice and stream data services and accomplish numerical analysis in combination with packet data traffic based on residual capacity equation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.444-454
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• 2004

To support diverse transmission requirements of multimedia applications, Quality of Service (QoS) should be provided in the Internet, where only the best-effort service is available. In this paper, we describe our recent effort on the implementation and verification of an extendable and flexible QoS allocation and resource management system based on the bandwidth broker model for realizing the IETF differentiated service (DiffServ). Focusing on the bandwidth issue over single administrative domain, the implemented system provides real-time resource reservation and allocation, delayed call admission control, simple QoS negotiation between sewer and users, and simple resource monitoring. The implemented system is verified by evaluating the performance of a resource-intensive application over the real-world testbed network.

• Convergence Security Journal
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• v.14 no.7
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• pp.75-84
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• 2014

The advancement in ubiquitous healthcare specifically in preventive healthcare can lead to longer life expectancy especially for the elderly patients. To aid in preventing premature loss of lives as well as lengthening life span, this research aims to implement the use of mobile and wireless sensor technology to improve the quality of life and lengthen life expectancy. The threats to privacy and security have received increasing attention as ubiquitous healthcare applications over the Internet become more prevalent, mobile and universal. Therefore, we propose Context-aware Service of U-Healthcare Application based Knowledge using Ontology in secure health information exchange. This research also applies ontology in secure information exchange to support knowledge base, context modeling, and context reasoning by applying the general application areas for ontologies to the domain of context in ubiquitous computing environments. This paper also demonstrates how knowledge base, context technologies, and mobile web services can help enhance the quality of services in preventive ubiquitous healthcare to elderly patients.

• The Journal of Society for e-Business Studies
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• v.21 no.4
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• pp.95-117
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• 2016

Entering aging society and increasing individual's interests on wellbeing lead to increasing demands of healthcare service and various healthcare related applications are providedon app market or Internet. These healthcare services could enhance user's health status if the users continuously use the service. In order to enhance effectiveness of a healthcare service, the service user should comply with recommendations or directions are provided by the service. However, previous studies of healthcare service are not considered effects of compliance intention on continuous usage. Hence, we tested how user's compliance intention effect on continuous usage intention of healthcare service based on theories of information system and medical information. Moreover, we found that compliance intention of users for healthcare service is an important factor on sustainability of healthcare service. Additionally, we investigated what factors are related with user's compliance intention.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.454-460
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• 2020

In recent years, the rapid increases in video distribution and viewing over the Internet have increased the risk of personal information exposure. In this paper, a method is proposed to robustly identify areas in images where a person's privacy is compromised and simultaneously blocking the object area by blurring it while rapidly tracking it using a prediction algorithm. With this method, the target object area is accurately identified using artificial neural network-based learning. The detected object area is then tracked using a location prediction algorithm and is continuously blocked by blurring it. Experimental results show that the proposed method effectively blocks private areas in images by blurring them, while at the same time tracking the target objects about 2.5% more accurately than another existing method. The proposed blocking method is expected to be useful in many applications, such as protection of personal information, video security, object tracking, etc.