• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2442-2450
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• 2010

Using sensor devices applied to various objects will be needed wireless network that it is easy to install in them. Tiny devices configured to processor that bas comparatively low computing ability are inappropriate to use devices that are wireless LAN, etc. In result, network devices needed to not only have simple communication protocol, but have Plug and Play function that it works as soon as it connects without installing any device driver. it also will industrially have both low power and low cost because of mobility of it. From IEEE 802.11 standard, WPAN(Wireless Personal Area Network) included in LAN is being developed by WPAN WG(Working Group) on area with low power consumption and low complexity. In addition to, it is standardizing MAC and PRY of the standard that is expected to wirelessly communicate within 10m. WPAN will be used generally in the more near future because of both low power and low cost of Zigbee. In this paper we designed zigbee based user authentication module for a automotive smart-key system.

• The KIPS Transactions:PartA
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• v.12A no.3 s.93
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• pp.205-214
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• 2005

Flash memory is at high speed used as storage of personal information utilities, ubiquitous computing environments, mobile phones, electronic goods, etc. This is because flash memory has the characteristics of low electronic power, non-volatile storage, high performance, physical stability, portability, and so on. However, differently from hard disks, it has a weak point that overwrites on already written block of flash memory is impossible to be done. In order to make an overwrite possible, an erase operation on the written block should be performed before the overwrite, which lowers the performance of flash memory highly. In order to solve this problem the flash memory controller maintains a system software module called the flash translation layer(FTL). Of many proposed FTL schemes, the log block buffer scheme is best known so far. This scheme uses a small number of log blocks of flash memory as a write buffer, which reduces the number of erase operations by overwrites, leading to good performance. However, this scheme shows a weakness of low page usability of log blocks. In this paper, we propose an enhanced log block buffer scheme, FAST(Full Associative Sector Translation), which improves the page usability of each log block by fully associating sectors to be written by overwrites to the entire log blocks. We also show that our FAST scheme outperforms the log block buffer scheme.

• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.371-382
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• 2007

In this paper, we propose a real-time sensor node platform that efficiently manages periodic and aperiodic tasks. Since existing sensor node platforms available in literature focus on minimizing the usage of memory and power consumptions, they are not capable of supporting the management of tasks that need their real-time execution and fast average response time. We first analyze how to structure periodic or aperiodic task decomposition in the TinyOS-based sensor node platform as regard to guaranteeing the deadlines of ail the periodic tasks and aiming to providing aperiodic tasks with average good response time. Then we present the application and efficiency of the proposed real-time sensor node platform in the sensor node equipped with a low-power 8-bit microcontroller, an IEEE802.15.4 compliant 2.4GHz RF transceiver, and several sensors. Extensive experiments show that our sensor node platform yields efficient performance in terms of three significant, objective goals: deadline miss ratio of periodic tasks, average response time of aperiodic tasks, and processor utilization of periodic and aperiodic tasks.

• Archives of design research
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• v.18 no.1 s.59
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• pp.17-26
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• 2005

Nowadays, display-contents are developing to an informative environment. that is under the logic of the media operating system. To perceive the media-environments and produce the cultural contents, the cultural designers seek to understand a skin structure from making up for shape. To appreciate operating system in data and database is not only systematization of form and contents of visual contents but also variety contents into multiple-platform and integrative environments. These days, the spectacle exhibition try to express for their surface design between algorithm of data and database. the information is expressing aesthetic which means presents the integrated contents through the play instinct environment to end-user. That was given web or game to participation is developing with the cellular device and ubiquitous computing system. in the linear perspective, the end-user should be immerse more and more hyper-simulation system because of the operating algorithm of database. To do this, human have need to get the information-ability from multi-platform society. In the virtual environment, database offer the experience of an unheard-of event to end-user that prepare the participants the circumstances priority of signifiers. To do that already based on a fixed sensibility endow with narrative of the freshness- experience.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.13-18
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• 2014

Sensor nodes are used for monitoring and collecting the environmental data via wireless sensor network. The wireless sensor network with various sensor nodes draws attention as a key technology in ubiquitous computing. Sensor nodes has very small memory capacity and limited power resource. Thus, it is essential to have energy efficient strategy for the sensor nodes. Since the sensor nodes are operating on the same frequency bands with ISM frequency bands, the interference by the devices operating on the ISM band degrades the quality of communication integrity. In this paper, the convolutional code is proposed instead of ARQ for the error control for the sensor network. The proposed convolutional code was implemented and the BER performance is measured. For the fixed transmitting powers of -19.2 dBm and -25dBm, the BER with various communication distances are measured. The packet loss rate and the retransmission rate are calculated from the measured BER. It is shown that the porposed method obtained about 9~12% and 12-19% reduction in retransmission rate for -19.2 dBm and -25 dBm respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5A
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• pp.459-468
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• 2006

Current routing in sensor networks focuses on finding methods for energy-efficient route setup and reliable relaying of data from the sensors to the sink so that the lifetime of the network is maximized. The existing routing protocols do not have routing tables to determine a path when packets are transferred. A sensor network by a routing table increases a cost of maintaining and updating a path, because sensor nodes have characteristics to be mobile and constrained capacity and resources. This paper proposes a new routing algorithm by broadcasting a bitmap in order to reduce the number of messages transferred when routing paths are established. Each node has a routing table with a bitmap, which contains link information. A bitmap is formed two-dimensional array, which consists of each row and column represented with a bit. The node only updates its own bitmap if it receives a bitmap from another adjacent nodes after the broadcasting. There by, each node has a bitmap with partial links information not total links information on the network. The proposed routing algorithm reduces the number of messages for routing establishment at least 10% compared with the previous algorithms.

• Journal of the HCI Society of Korea
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• v.1 no.2
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• pp.35-42
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• 2006

The importance of interface agent as user interface increases in the ubiquitous computing environment. It is essential that an interface agent can develop social relationship with users. We propose that self-disclosure, a major factor to form and maintain human relationship, can be useful to achieve this goal. This study examined the effects of the degree of a computer agent's self-disclosure on the users' social responses. The experiment was conducted in a 2(intimacy of agent's disclosure: high vs. low) by 2(amount of agent's disclosure: high vs. low) between-group design. The results show that: 1) reciprocity of self-disclosure was found in both sub-dimensions (intimacy and amount) of self-disclosure; 2) in case that participants received highly intimate self-disclosure from the agent, social attraction, trustworthiness and expectation of mutual influence toward agent were lower than when the agent's disclosure was less intimate. These findings suggest that the intimacy of agent's self-disclosure can affect on gathering user information and human-agent relationship formation separately. While agent's highly intimate disclosure can be useful to gather user information, agent's appropriate disclosure can be useful to form positive user-agent relationship.

• Convergence Security Journal
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• v.14 no.7
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• pp.3-8
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• 2014

Recently, A utilization request of the U-Healthcare services are increasing rapidly. This is because the increase in smartphone users and ubiquitous computing technology was developed. Furthermore, the demand for access to and use of medical information systems is growing rapidly with a smartphone. This system have the advantage such as they can access from anywhere and anytime in the healthcare information system using their smartphone quickly and easily. But this system have various problems that are a privacy issue, the location disclosure issue, and the potential infringement of personal information. this problems are arise very explosive. Therefore, we propose a secure information security system that can solve the security problems in healthcare information systems for healthcare workers using smartphone. Our proposed system, doctors record, store, modify and manage patient medical information and this system would be safer than the existing healthcare information systems. The proposed system allows the doctor to perform further authentication by transmitting using SMS to GOTP message when they accessing medical information systems. So our proposed system can support to more secure system that can protect user individual information stealing and modify attack by two-factor authentication scheme. And this system can support confidentiality, integrity, location information blocking, personal information steal prevent using cryptography algorithm that is easy and fast.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.33-41
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• 2018

The purpose of this study is to develop more accurate and robust emotion prediction neural network (EPNN) model by combining heart rate variability (HRV) and neural network. For the sake of improving the prediction performance more reliably, the proposed EPNN model is based on various types of activation functions like hyperbolic tangent, linear, and Gaussian functions, all of which are embedded in hidden nodes to improve its performance. In order to verify the validity of the proposed EPNN model, a number of HRV metrics were calculated from 20 valid and qualified participants whose emotions were induced by using money game. To add more rigor to the experiment, the participants' valence and arousal were checked and used as output node of the EPNN. The experiment results reveal that the F-Measure for Valence and Arousal is 80% and 95%, respectively, proving that the EPNN yields very robust and well-balanced performance. The EPNN performance was compared with competing models like neural network, logistic regression, support vector machine, and random forest. The EPNN was more accurate and reliable than those of the competing models. The results of this study can be effectively applied to many types of wearable computing devices when ubiquitous digital health environment becomes feasible and permeating into our everyday lives.

• Information Systems Review
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• v.8 no.2
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• pp.29-49
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• 2006

The introduction of the Digital Economy has formed a new market producing and trading information. Depending on the current contexts, each user evaluates identical information differently. It is difficult, even though important, to create and deliver the information customized to individual users by using some factors as time, location, and their personal characteristics. Information value, therefore, could be influenced by the capability of information systems to delivery useful information based on individual contexts to the right user immediately at the right time. From this point of view, we argue mobile systems which are able to be aware of individual contexts and deliver contextual information in real time can improve information value easily than other systems can. This research presents the results of an empirical test about antecedents to mobile advertising value. Though context relevance doesn't influence directly mobile advertising value, it plays an important role enhancing information usefulness which has great influence on mobile advertising value. Moreover, to supply information connected with users' context overcomes the effect of irritation. Lastly, entertainment can improve mobile advertising value as satisfying user's hedonic desire beyond the information source supporting decision making.