• Korean Journal of Adult Nursing
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• v.20 no.5
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• pp.778-790
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• 2008

Purpose: This study was conducted to develop Web-based multimedia contents for supporting student nurses' clinical practice on critical care, and to evaluate learners' responses. Methods: Based on the steps of Assessment, Design, Development, Implementation, & Evaluation(ADDIE) model, a total of 13 self-directed learning modules including live lectures and real video clips were developed through faculty collaboration of nine nursing colleges in Gwangju and Chonnam province. The finally developed multimedia contents were published on the Web of the learning management system at a local e-learning center. Results: The Web contents were evaluated after self-learning by 81 junior college nursing students who were encouraged to study it at their own pace during their two-week clinical practice at a medical or surgical intensive care unit of a university hospital and two hospitals. The knowledge (t = -27.66, p < .001) and self-evaluated clinical performance level(t = 7.54, p < .001) were significantly increased after learning of the Web contents and clinical practice, and satisfaction level that measured post-test only was 4.0 out of 5 point. Conclusion: The use of Web contents for critical care need to be extended as a complimentary material in a class room lecture or clinical practice of students to increase their self-learning ability and understandings of clinical knowledge and situation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.192-198
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• 2008

In this paper, we propose a scheme that improves the transmission performance of realtime multimedia data in wireless Local Area Network (LAN) environment, through the dynamical control of Transmission Opportunity (TXOP) period of the IEEE 802.11e HCCA Medium Access Control (MAC). The existing schedulers which determine the frame transmission time and its duration could not appropriately cope with the change of physical transmission rate, since the TXOP period has remained unchanged with the change of transmission rate of the wireless station. Our scheme is devised to keep the transmission performance of real-time multimedia data effectively unchanged by making TXOP period be extended when the transmission rate gets reduced. The proposed scheme is experimented along with IEEE 802.11e reference model using NCTUns simulator, which shows that the multimedia data is effectively delivered with the change of transmission rate as the distance between the wireless station and its access point increases.

• Korean Management Science Review
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• v.24 no.2
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• pp.95-114
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• 2007

The main attractant of portable multimedia player(PMP), is often their versatility : being able to load and play different formats of video, audio, digital images, and interactive media. In this paper, we investigate the factors influencing the usage the PMP, based on the extended version of the Technology Acceptance Model. Using the data collected from online survey, we show that perceived usefulness, perceived ease of use, and perceived enjoyment are the major determinants for using PMP. Factors, including ubiquitousness, community, and image are shown to directly or indirectly determine the level of perceived usefulness and ease of uses. In addition, we classify PMP users into two groups, users seeking hedonic value and utilitarian value, and examine the differences in path coefficients. Properties of the causal paths, including standardized path coefficients, the significance of difference, in the hypothesized model, are also presented, so that we can investigate the relative influences of different dominants, demonstrating how two groups differ in their decision-making processes regarding the PMP usage.

• Journal of Korea Multimedia Society
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• v.21 no.5
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• pp.545-557
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• 2018

The Global Positioning System (GPS) has become popular and widely used in many fields from military to civilian applications. However, GPS signals are suffered from interference due to its weak signal over wireless channel. There are many types of interference, such as jamming, blocking multipath, and spoofing, which can mislead the operation of GPS receiver. In this paper, vector-based tracking loop model with integrity check is proposed to detect and mitigate the harmful effect of interference on GPS receiver operation. The suggested methods are implemented in the tracking loop of GPS receiver. As a first method, integrity check with carrier-to-noise ratio (C/No) monitoring technique is applied to detect the presence of interference and prevent contaminated channels out of tracking channels to calculate position. As a second method, a vector-based tracking loop using Extended Kalman Filter with adaptive noise covariance according to C/No monitoring results. The proposed methods have been implemented on simulated dataset. The results demonstrates that the suggested methods significantly mitigate interference of Additive White Gaussian Noise (AWGN) and improve position calculation by 44%.

• Journal of Korea Multimedia Society
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• v.18 no.9
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• pp.1105-1117
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• 2015

During the last decade, the business infrastructure has become digital with increased interconnections among products, processes, and services. Across many firms spanning different industries and sectors, digital technologies are fundanmentally transforming business stratiges, business processes, firm capabilities, productes and services, and key interfirm relationships in extended business networks. With the emergence of smartphones, the paradigm of the ICT industry is rapidly changing as the line between global and local markets are being blurred. In the changing global environment, although some game companies are accelerating the improvement of their global competitiveness and cases of successes of venture enterprises by developing biosimilar technology are being discovered, majority of ICT companies are focusing on limited marketing activities to get subcontracts or projects from large companies. Thus the aim of this study is to find out how digital ecosystems evolve and how business models and strategies have changed of individual companies according to the evolution of the digital ecosystems.

• Journal of Korea Multimedia Society
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• v.2 no.3
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• pp.252-264
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• 1999

The key characteristic of video data is its spatial/temporal relationships. In this paper, we propose an content based video retrieval system based on hierarchical data structure for specifying the temporal semantics of video data. In this system, video data's hierarchical structure temporal relationship, inter video object temporal relationship, and moving video object temporal relationship can be represented. We also implemented these video data's temporal relationship into an object-relational database management system using inheritance, encapsulation function overloading, etc. So more extended and richer temporal functions can be used to support a broad range of temporal queries.

• Journal of Korea Multimedia Society
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• v.4 no.1
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• pp.46-55
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• 2001

In this paper, a new voice activity detection method estimating SNR of enhanced speech with extended spectral subtraction (ESS) is proposed. Voice activity detection is performed by putting an second Wiener filter behind an Wiener filter used in the ESS to estimate speech and noise power of output signal of first Wiener filter. The proposed voice activity detection method does not require many computational loads and performs well under severe input SNR. Boll's spectral substraction algorithm with proposed voice activity detection was compared to ESS under several noise environment having different time-frequency distributions. During speech and non-speech activity, performance of Boll's spectral substraction algorithm with proposed voice activity detection is superior to that of ESS.

• Journal of Korea Multimedia Society
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• v.2 no.4
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• pp.490-495
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• 1999

In this paper, a method of improving the learning time and convergence rate is proposed to exploit the advantages of artificial neural networks and fuzzy theory to neuron structure. This method is applied to the XOR Problem, n bit parity problem which is used as the benchmark in neural network structure, and recognition of digit image in the vehicle plate image for practical image application. As a result of the experiments, it does not always guarantee the convergence. However, the network showed improved the teaming time and has the high convergence rate. The proposed network can be extended to an arbitrary layer Though a single layer structure Is considered, the proposed method has a capability of high speed 3earning even on large images.

• Journal of Korea Multimedia Society
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• v.12 no.5
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• pp.728-736
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• 2009

We propose a method using the genetic algorithm to solve the maximum set cover problem. It is needed for scheduling the power of sensor nodes in extending the lifetime of the wireless sensor network with variable sensing range. The existing Greedy Heuristic method calculates the power scheduling of sensor nodes repeatedly in the process of operation, and so the communication traffic of sensor nodes is increased. The proposed method reduces the amount of communication traffic of sensor nodes, and so the energies of nodes are saved, and the lifetime of network can be extended. The effectiveness of this method was verified through computer simulation, and considering the energy losses of communication operations about 10% in the network lifetime is improved.

• Journal of Korea Multimedia Society
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• v.13 no.6
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• pp.901-910
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• 2010

$IP^2$, as an extended concept of the next generation IMT network, is a concept of basically supporting mobility using two steps of IP address (i.e. IPha (IP Host address) and IPra (IP routing address)) in IP backbone network. Current $IP^2$system has a shortcoming of excess usage of network resources caused by sending paging messages to all cells in LA (Location Area) in paging procedure. Considering the evolving direction of network, which is taking mobility with various speed and integration of devices into consideration, this shortcoming must be overcome. In this paper, we proposed a method to reduce time and memory for paging by maintaining current information of MN (Mobile Node) not in Active state with proxy server. Performance evaluation based on NS-2 simulations has shown that the efficiency of network resources is improved in the proposed method.