• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.1
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• pp.153-160
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• 2016

In this paper, we propose a system that tracks the position of the passengers and sailors using a Bluetooth-based Beacon in the ship. The position of the tracking passengers, sometimes fatal emergencies of the rescue team, such as the sinking of the ship is utilized in order to efficiently and quickly rescue the passengers, and the collected data can be utilized additionally by grasping the flow of human traffic patterns. The system proposed in this paper, install MAC data acquisition called AP (Access Point) for each cabin, and in the installed AP retrieves Tag of the information provided to the passenger and collected. A Tag has only its own MAC Address to the privacy, no user information is not collected. All data communication by sending and receiving MAC Address was only to ensure anonymity.

• The Journal of the Korea Contents Association
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• v.16 no.11
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• pp.83-90
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• 2016

In this paper, we performed the analysis of transmission performance for Collision Free Period(CFP) supported by the low-power communication technology, IEEE 802.15.4 MAC (Media Access Control). For the analysis, periodic traffic, original service target of CFP, is considered and, according to the Quality of Service required, packet arrival pattern to MAC layer is categorized as batch and non-batch, and analysis on throughput, delay, and energy is performed for those patterns. On the basis of the obtained analysis, performance comparison with Collision Avoidance Period(CAP) is carried out for the health care applications that generate periodic traffic such as Pedometer, ECG, EMG. The evaluation confirms that CFP is more energy efficient for healthcare applications that generate periodic and time-critical traffic and moreover for the application with high bandwidth requirement CFP achieves up to 46% energy savings compared to CAP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.1999-2007
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• 2010

Proxy Mobile IPv6(PMIPv6) is a network-based mobility management protocol and it does not require mobile node's involving in mobility management. In PMIPv6, the Mobile Access Gateway (MAG) incurs a high signaling cost to update the location of a mobile node to the remote Local Mobility Anchor (LMA) if it moves frequently. It may cause excessive signaling traffic and increase a high traffic load on LMA. Therefore, we propose a new mobility management scheme in proxy mobile IPv6 networks with dynamic paging support. To minimize signaling overhead, in our proposal, the size of the paging area is determined dynamically according the changes of mobility and traffic patterns of the mobile node. An analytic model is applied to determine the optimal size of the paging area. The cost analysis using fluid flow model presented in this paper shows that our proposal can achieve performance superior that of PMIPv6 scheme.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.542-546
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• 2008

Recently dual-port SDRAM (DPSDRAM) architecture tailored for dual-processor based mobile embedded systems has been announced where a single memory chip plays the role of the local memories and the shared memory for both processors. In order to maintain memory consistency from simultaneous accesses of both ports, every access to the shared memory should be protected by a synchronization mechanism, which can result in substantial access latency. We propose two optimization techniques by exploiting the communication patterns of target applications: lock-priority scheme and static-copy scheme. Further, by dividing the shared bank into multiple blocks, we allow simultaneous accesses to different blocks thus achieve considerable performance gain. Experiments on a virtual prototyping system show a promising result - we could achieve about 20-50% performance gain compared to the base DPSDRAM architecture.

• Journal of the Korean Society for Library and Information Science
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• v.48 no.1
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• pp.257-276
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• 2014

The purpose of this study is to investigate the patterns and barriers of the Internet for the elderly adults in Korea. Data was collected through the face to face interview using a questionnaire for the residence of Daegu and Kyungsang Buk-Do areas targeted over the 60-years-olds elder adults. A total of 119 valid response data were analyzed with the descriptive statistics and the group differences by age and gender using SPSS 18.00. It found that the most of the elder adults access the Internet to seek the entertainment contents, the knowledge-related contents, and the cultural and art contents. They spend most of the Internet online session to do searching information and enjoying movie and music. However, there were age differences and gender differences within the subjects. The complexity of computer and the Internet usage is one of the barriers for the Internet access, and they suggest that a customized education and training courses of computer literacy for the elderly adults would be the ways of resolve those obstructions.

• Journal of Convergence for Information Technology
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• v.10 no.11
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• pp.16-22
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• 2020

Since it is difficult for individual power producers and non-professionals who lack basic knowledge to control, manage, and operate facilities through EMS (Energy Management System), augmented reality and virtual reality monitoring systems are applied. However, in the existing systems, data access efficiency is inferior due to the process of analyzing column values for analog signal values collected from sensors and converting data after combining the columns. In addition, high-speed operation processing is difficult due to a large number of indexes for accommodating access patterns for various analog signal waveforms. Therefore, in this paper, a bitmap generator is inserted into a non-tree structure to convert the data collected from power facilities into physical property information, and the converted information is encrypted with a common key, so that the resources for the resources shared between each device are We propose a method of exchanging data for an augmented reality-based power system that is controlled by measurement.

• The Journal of Society for e-Business Studies
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• v.15 no.4
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• pp.101-121
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• 2010

This paper presents an intelligent prefetching technique that significantly improves performance of hybrid fash-disk storage, a combination of flash memory and hard disk. Since flash memory embedded in a hybrid device is much faster than hard disk in terms of I/O operations, it can be utilized as a 'cache' space to improve system performance. The basic strategy for prefetching is to utilize sequential pattern mining, with which we can extract the access patterns of objects from historical access sequences. We use two techniques for enhancing the performance of hybrid storage with prefetching. One of them is to modify a FAST algorithm for mapping the flash memory. The other is to extend the unit of prefetching to a block level as well as a file level for effectively utilizing flash memory space. For evaluating the proposed technique, we perform the experiments using the synthetic data and real UCC data, and prove the usability of our technique.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.3
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• pp.1-11
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• 2002

The purpose of this study is to construct an evaluation criteria based on the relative importance and various combinations of each evaluation index and then to appraise urban biotope in terms of nature experience and recreation. After the standard of evaluation had been developed through the review of existing literature, the relative importance of the evaluation index through expert survey was determined, and the evaluation model to assess biotope value was established. The results of this study are as follows; 1) We have constructed the seventeen evaluation criteria through literature reviews, and have provided relative importance to each evaluation index of the natural in biotope, the diversity of landscape patterns, the appearance-existence of water space, the special landscape elements, and the access based on the results of expert survey. and then we have constructed an evaluation system using the relative importance criteria. 2) To evaluate urban biotope using the evaluation system constructed, we selected 14 sites. The final evaluation results of each site is as follows; The first grade areas are the water space with semi-natural style in front of Gangchon Woobang apartments, the forest zone near Page Temple at Mt. Palgong, the edge area of Jisan and Gosan and the tendril yard against Anshim middle school. The second grade areas are Hyomyung elementary school, the farm land behind the third Anshim Jugong apartment, Ehyun put and the swampy land in front of the Kangchon and Anshim construction site. The third grade areas are Seohan and Hwasung high-rise apartments at Beummul-Dong, the Korea Manpower Agency in the Sungseo industrial zone, and the adjacent area of St. Tongil. The only fourth grade area is the commercial zone near Taegu Department Store. 3) It is highly useful to evaluate urban biotope using the evaluation criteria constructed for this research, the evaluation criteria we developed may be difficult to encompass all expert opinion and the period of space-formation is difficult to estimate urban biotopes. In the future, it is necessary to gather the basic data suitable to estimate biotope and it is necessary to develop detailed evaluation criteria applicable to estimate every biotope that has specific property.

• Journal of the Korean Geographical Society
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• v.40 no.5 s.110
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• pp.514-532
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• 2005

The purpose of this study is to critically examine conventional spatial measures of individual accessibility, which are based on the notion of spatial proximity, the single reference location, and the unlinked travel model. Using space-time accessibility measures with the travel-activity diary data set of Portland Metro, US, three expectations from spatial measures on spatial patterns of individual accessibility were empirically examined: (1) does individual accessibility decrease with an increase of distance from the CBD?; (2) does the spatial pattern of accessibility resemble that of urban opportunity density pattern?; and (3) are spatial patterns of individual accessibility of different socio- demographic population groups basically similar as people in the same area share the same geographic characteristics regardless of gender, race, age, and so on? First of all, the results showed that spatial variations in individual accessibility were not directly determined by spatial proximity and opportunity density as suggested by previous accessibility measures. The spatial pattern of individual accessibility was dramatically different from that of urban opportunity density High peaks of accessibility level were found far away from the CBD and regional centers. This finding might be associated with the importance of multi-reference locations and linked travels in shaping accessibility in reality. Furthermore, this study found that spatial patterns of accessibility clearly differ between men and women. These findings suggest that access requires more than proximity, and that the interaction between person-specific space-time constraints and the consequential availability of urban opportunities in space-time renders different accessibility experiences to people even in the same region, which would be one of the key ingredients missing from conventional spatial measures of accessibility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.557-562
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• 2020

In the non-face-to-face learning environment forced into effect by the COVID-19 pandemic, online learning is being adopted as a major educational technique. Given the lack of research on how online learning patterns affect academic performance, this study focuses on the number and duration of online video learning sessions as a major factor based on midterm and final exams, and with a formative assessment for each type of learning. The correlation of the learning effects was analyzed. The analysis focused on computer programming subjects, which are among the most difficult liberal arts subjects for arts and science students at the university level. The analysis of cases of actual students showed no correlation among weekly formative assessments, the number of learning sessions, and the learning duration. On the other hand, the number of learning sessions (r=.39 p<0.05) and learning duration (r=.42 p<0.05) were correlated with the midterm and final exams. Elements, such as SMS text, bulletin board, and e-mail, were excluded from the analysis because not all students have access to them. Therefore, the results can be improved if future analysis of the students' learning patterns in a non-face-to-face lecture environment is performed considering more factors/elements and the learners' needs.