• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.4
• /
• pp.1192-1207
• /
• 2014

Dynamic spectrum sharing is a key technology to improve spectrum utilization in wireless networks. The elastic spectrum management provides a new opportunity for licensed primary users and unlicensed secondary users to efficiently utilize the scarce wireless resource. In this paper, we present a game-theoretic framework for dynamic spectrum allocation where the primary users rent the unutilized spectrum to the secondary users for a monetary profit. In reality, due to the ON-OFF behavior of the primary user, the quantity of spectrum that can be opportunistically shared by the secondary users is limited. We model this situation with the renewal theory and formulate the spectrum pricing scheme with the Bertrand game, taking into account the scarcity of the spectrum. By the Nash-equilibrium pricing scheme, each player in the game continually converges to a strategy that maximizes its own profit. We also investigate the impact of several properties, including channel quality and spectrum substitutability. Based on the equilibrium analysis, we finally propose a decentralized algorithm that leads the primary users to the Nash-equilibrium, called DST. The stability of the proposed algorithm in terms of convergence to the Nash equilibrium is also studied.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.47 no.2
• /
• pp.153-163
• /
• 2011

The main purpose of this study is to understand the marketing approaches and strategies that are used to disseminating biodegradable fishing gears and distinguish the cognition and the non-cognition group's attitudes on the product. We used a technology acceptance model for analyzing product attributes and its impacts on fishers' purchase. The result of this research shows that 'perceived usefulness and easiness of use' have positive effect on 'purchase intention,' and then give impacts on 'purchase intention' for the entire respondents. For the cognitive respondents these factors have influence on 'attitude' but they do not affect 'purchase decision.' However, 'perceived usefulness and easiness of use' have much positive impact on 'purchase intention.' In the non-cognition group, the 'perceived intention' and 'company and country of manufacturers' have direct positive effect on 'purchase intention' through 'attitude' and also 'on 'purchase intention.' This research provides some meaningful policy implications on further development and technology marketing of biodegradable fishing gears.

• Journal of the Korean Society of Earth Science Education
• /
• v.8 no.2
• /
• pp.206-217
• /
• 2015

The purpose on this study is to identify how effectively experiential learning involving eco-activities make changes in environmental literacy and scientific attitude of elementary students by categorizing those activities into 5 fields of "marine", "rivers", "ecosystem", "climate" and "recycling" and applying those scheme specifically to 5th graders in a elementary school. The conclusion of this study is following. Firstly, after scientific attitude are applied to subjects, a significant disparity was found between experiment group and control group throughout all parts of environmental literacy. In the cognitive category, each specialist concerning his or her own topic was invited to educate the students, and subsequently a positive impact was detected in the category of environmental issue knowledge. In behavioral category, having eco-activities made a significant disparity in all sub-categories of environmental function, active participation, saving activities, recycling activities and so forth. Secondly, experiential learning involving eco-activities made a significant disparity between the two groups in terms of Scientific Attitude, showing effectiveness in all sub-categories except curiosity.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.6
• /
• pp.2838-2858
• /
• 2019

Traditional channel models for vehicle-to-vehicle (V2V) communication usually assume fixed velocity in static scattering environment. In the realistic scenarios, however, time-variant velocity for V2V results in non-stationary statistical properties of wireless channels. Dynamic scatterers with random velocities and directions have been always utilized to depict the non-stationary statistical properties of the channel. In this paper, a non-stationary geometry-based cooperative scattering channel model is proposed for multiple-input multiple-output (MIMO) V2V communication systems, where a birth-death process is used to capture the appearance and disappearance dynamic properties of moving scatterers that reflect the time-variant time correlation and Doppler spectrum characteristics. Moreover, our model has more straight and concise to study the impact of the vehicular traffic density on channel characteristics and thus avoid complicated procedure in deriving the analytical expressions of the channel parameters and functions. The numerical results validate our analysis and demonstrate that setting important parameters of our model can appropriately build up more purposeful measurement campaigns in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.12
• /
• pp.4664-4681
• /
• 2020

Modulation recognition (MR) plays a key role in cognitive radar, cognitive radio, and some other civilian and military fields. While existing methods can identify the signal modulation type by extracting the signal characteristics, the quality of feature extraction has a serious impact on the recognition results. In this paper, an end-to-end MR method based on long short-term memory (LSTM) and the gated recurrent unit (GRU) is put forward, which can directly predict the modulation type from a sampled signal. Additionally, the sliding window method is applied to fast-changing mixed-modulation signals for which the signal modulation type changes over time. The recognition accuracy on training datasets in different SNR ranges and the proportion of each modulation method in misclassified samples are analyzed, and it is found to be reasonable to select the evenly-distributed and full range of SNR data as the training data. With the improvement of the SNR, the recognition accuracy increases rapidly. When the length of the training dataset increases, the neural network recognition effect is better. The loss function value of the neural network decreases with the increase of the training dataset length, and then tends to be stable. Moreover, when the fast-changing period is less than 20ms, the error rate is as high as 50%. As the fast-changing period is increased to 30ms, the error rates of the GRU and LSTM neural networks are less than 5%.

• International Journal of Computer Science & Network Security
• /
• v.22 no.1
• /
• pp.21-26
• /
• 2022

This study touched on the effect of the different electronic course designs on the programming skills of university students. The researcher used the experimental research design of a quasi-experimental of two experimental groups to achieve the objectives of the study. The first group underwent an electronic course designed in the holistic pattern, and the second group was taught a course in a sequential pattern. This experimental design was intended to measure the impact of these two learning modes on the learners' cognitive and performance achievement of programming skills. An achievement test and observational form were the data collection tools. Data were analyzed statistically using Pearson correlation, Mann Whitney Test, and Alpha Cronbach. The findings revealed statistically- significant differences between the mean scores of the students of the first and second experimental groups in favor of the former concerning the observational form and the latter in the cognitive test. Based on the findings, some recommendations are suggested. Due to their effectiveness in the educational process, expanding using the e-courses at universities is vital. The university teachers are highly recommended to design e-courses and provide technical and material support to the e-courses user to fulfill their design purpose.

• Journal of Korea Multimedia Society
• /
• v.25 no.4
• /
• pp.649-659
• /
• 2022

The most important factor in pre-school children's psychological perception is ease of learning, and the closest measure is "natural" interaction. This study aims to explore the potential of tangible user interfaces (TUI) for AR collaboration for children's cognitive development. The conceptual model is constructed by analyzing physical interaction, spatial perception and social collaboration on the usability of TUI, to explore the role of TUI in pre-school children's cognition. In the empirical study, children aged 3-6 were taken as research objects. The experimental tool is "Plugo" education application. Parents answered questionnaires after observing their children's use. Research shows that physical interaction are the most critical factor in TUI. TUI is beneficial to the cultivation of spatial ability. The results are as follows: 1. Cronbach's Alpha and KMO were 0.921 and 0.965, which were significant and passed the reliability and validity test. 2. Through confirmatory factor analysis (model fit index, combinatorial validity), we found that physical interaction were closely related to usability. 3. The path analysis of the relationship proves that usability has a significant impact on the cultivation of pre-school children's spatial ability.

• Educational Technology International
• /
• v.13 no.2
• /
• pp.283-312
• /
• 2012

Problem-solving ability is one of the most important learning outcomes for students to compete and accomplish in a knowledge-based society. It has been empirically proven that visualization plays a central role in problem-solving. The best performing problem-solver might have a strong visualization tendency. However, there is little research as to what factors of visualization tendency primarily related to problem-solving ability according to phases of problem-solving. The purpose of this study is to identify the relationship between visualization tendency and problem-solving ability, to determine which factors of visualization tendency influence problem-solving ability in each phase of problem-solving, and to examine different problem-solving ability from the perspective of the levels of visualization tendency. This study has found out that visualization tendency has a significant correlation with problem-solving ability. Especially, Generative Visualization and Spatial-Motor Visualization as sub-visualization tendency were more strongly related to each phase of problem-solving. It indicates that visualization tendency to generate and operate mental processing can be considered a major cognitive skill to improve problem-solving ability. Furthermore, students who have high visualization tendency also have significantly higher problem-solving ability than students with low visualization tendency. It shows that the levels of visualization tendency can predict variables related to students' problem-solving ability.

• Journal of Digital Convergence
• /
• v.18 no.11
• /
• pp.81-86
• /
• 2020

Green consumption has drawn attention from various sectors of society recently. However, the "mismatch" of awareness and behavior remains despite consumers' heightened environment-friendly awareness. Based on the theory of emotional cognition and cognitive dissonance, This study examined the impact of consumers' expected guilt on green consumption intentions, and also introduced consumer cognitive utility to further uncover the mechanism in the process of influence by a survey of young Chinese people born after the 80s. Path analysis and hypothesis verification using AMOS showed that consumers' expected guilt not only directly affects the intention of green consumption, but also indirectly affects the intention of green consumption through the intermediation of cognitive utility.

• Korean Journal of Cognitive Science
• /
• v.24 no.4
• /
• pp.301-321
• /
• 2013

For the task of sentence ordering, this paper attempts to utilize the Entity-Grid model, a type of entity-based modeling approach, as well as Latent Semantic analysis, which is based on vector space modeling, The task is well known as one of the fundamental tools used to measure text coherence and to enhance text generation processes. For the implementation of the Entity-Grid model, we attempt to use the syntactic roles of the nouns in the Korean text for the ordering task, and measure its impact on the result, since its contribution has been discussed in previous research. Contrary to the case of German, it shows a positive result. In order to obtain the information on the syntactic roles, we use a strategy of using Korean case-markers for the nouns. As a result, it is revealed that the cues can be helpful to measure text coherence. In addition, we compare the results with the ones of the LSA-based model, discussing the advantages and disadvantages of the models, and options for future studies.