• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.815-821
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• 2021

This study addresses on the design of performance monitoring system for the time synchronization service of the enhanced long-range navigation (eLoran) system, which has a representative ground-wave radio broadcast system capable of providing positioning, navigation, timing and data (PNT&D) services. The limitations of time-synchronized systems due to the signal vulnerabilities of the global navigation satellite system (GNSS) are explained, and the performance monitoring system for the eLoran timing service as a backup to the GNSS is proposed. The time synchronization service using eLoran system as well as system configurations and the user requirements in the differential Loran (dLoran) system are described to monitor the time synchronization performance. The results of the designed system are presented for long-term operation in the eLoran testbed environment. As the results of time performance monitoring, we were able to verify the time synchronization precision within 43.71 ns without corrections, 22.52 ns with corrections. Based on these results, the eLoran system can be utilized as a precise time synchronization source for GPS timing backup.

• School Mathematics
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• v.14 no.1
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• pp.1-28
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• 2012

The purpose of the study are to identify factors of mathematical visualization through the thirty students of highschool 2nd year and to investigate how each visualization factor is used in mathematics problem solving process. Specially, this study performed the qualitative case study in terms of the five of thirty students to obtain the high grade in visuality assessment. As a result of the analysis, visualization factors were categorized into mental images, external representation, transformation or operation of images, and spacial visualization abilities. Also, external representation, transformation or operation of images, and spacial visualization abilities were subdivided more specifically.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.12
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• pp.2563-2567
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• 2011

Advances in smart sensors, embedded systems, low-power design, ad-hoc networks and MEMS have allowed the development of low-cost small sensor nodes with computation and wireless communication capabilities that can form distributed wireless sensor networks. Time information and time synchronization are fundamental building blocks in wireless sensor networks since many sensor network applications need time information for object tracking, consistent state updates, duplicate detection and temporal order delivery. Various time synchronization protocols have been proposed for sensor networks because of the characteristics of sensor networks which have limited computing power and resources. However, none of these protocols have been designed with time representation scheme in mind. Global time format such as UTC TOD (Universal Time Coordinated, Time Of Day) is very useful in sensor network applications. In this paper we propose network time protocol extension for global time presentation in wireless sensor networks.

• Cartoon and Animation Studies
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• s.13
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• pp.83-96
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• 2008

Digital production method in animation has enabled us to reconstruction the real world in the way we had sought in visual all. However, spectator's visual desire is not satisfied with mere photographic visual reconstruction. It demands traditional picturesque qualify with involves a great deal of contingencies and errors. Naturally, Digital film technology has also sometimes tried to simulate analogue technique such as hand drawing so on. This is not caused by nostalgia, but by recursive instinct. The spectator's visual desire for media doesn't remain only precision of real world but require mental demand on successive visual and perceptive errors while repealing ripeness of new media and going through perception and recognition. This spectator's desire and visual art technology pursuits variously its visual perfection in history.

• Journal of The Korean Association For Science Education
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• v.38 no.2
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• pp.161-170
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• 2018

Various forms of visual representations enable scientific discovery and scientific reasoning when scientists conduct research. Similarly, in science education, visual representations are important as a means to promote students' understanding of science concepts and scientific thinking skills. To provide a framework that could facilitate the effective use of visual representations in science classroom and systemic science education research, a visual representation competence taxonomy (VRC-T) was developed in this study. VRC-T includes two dimensions: the type of visual representation, and the cognitive process of visual representation. The initial categories for each dimension were developed based on literature review. Then validation and revision was made by conducting teachers' workshop and survey to experts. The types of visual representations were grouped into 3 categories (descriptive, procedural, and explanative representations) and the cognitive processes were grouped into 3 categories (interpretation, integration, and construction). The sub categories of each dimension and the validation process would be explained in detail.

• Journal of Broadcast Engineering
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• v.15 no.5
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• pp.607-616
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• 2010

The methods developed to measure visual fatigue so far are quite few and lack of validity, and more importantly, they do not figure out the complex properties of the visual fatigue. The purpose of the research was to analyze the factors comprising the visual fatigue and to develop the method to measure it validly. The results are summarized as follows. First, we found that the 3D visual fatigue was comprised of four independent factors (visual stress, eye pain, body pain and image blurring factors). Second, we developed 29 items that measure four factors of 3D visual fatigue. Finally, the watching duration and binocular disparities affected the visual fatigue as had been expected. These results imply that the developed method does measure the three dimensional fatigue validly.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.289-292
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• 2012

Presently, there is the blind of about 20~300,00 people including didn't register in Korea Usually, they used white stick when they walk outside. There is the blind receiving the help of the guide dog but a small number of blind uses due to many composite problems including the cost problem, and etc. Presently, the guidance service aid long for the blind which is commonly used adheres the RFID tag to the white stick. It remains at the level of the extent of making the cover block and RF communication by using this. The recognition distance is short. This is the actual condition in which it is difficult to determine the location of the clear obstacle and size and form, it doesn't become the help which is actually big in the walk of the blinds. Thus, in this paper, the investigation of 'Smart Portable Navigation System' development of the Cortex-A8 Platform base tries to be handled so that the blinds can walk easily.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.157-168
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• 2006

Spatial detection system such as AVI, GPS, and Beacon etc. can provide spatial travel time only after a vehicle Passes through a road section. In this context, majority of the existing studies on the link travel time estimation area has focused on the arrival time-based link travel time estimation. rather than departure time-based link travel time estimation. Even if some of the researches on this area have developed departure time-based link travel time estimation algorithms, they are limited in that they are not applicable in a real-time mode. The objective of this study is to develop an departure time-based link travel time estimation algorithm which is applicable in a real-tine mode. Firstly, this study discussed the tradeoff between accuracy and timeliness of the departure time-based on-line link travel time estimates. Secondly, this study developed an departure time-based on-line link travel time estimation algorithm which utilizes the Baysian inference logic. It was found that the proposed approach could estimate departure time-based link travel times in a real-time context with an acceptable accuracy and timeliness.

• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.121-131
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• 2011

Visual tactility implies feelings of touch through sight. To be exact, the eyes are doing the touch rather than the body and the subject concerned will experience the sensation of touch by looking at an object similar to that of physical touch. This is quasi tactility to put it simply and it can be defined as to touch with the eyes. This can not only provide opportunities to experience something close to reality but also another completely different form of modern experience. Experiencing visual tactility through the use of the web permits lavish communication between the user and the designer. This paper has reorganize the concept of visual tactility, characteristic and way to use in digital contents. Visual tactility stimulates the users' emotion as such. If it was to be utilized to develop edutainment contents or web sites will foster children's capability to develope problem solving skills and raise efficiency in creative learning, and prolong the period of concentration in order to encourage revisits to the place and extend the time of stay.

• The Journal of the Korea Contents Association
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• v.11 no.5
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• pp.489-499
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• 2011

While lots of information service providers utilize the information visualization to deliver information clearly and efficiently, the misuse of information visualization can occur many problems. We evaluated and analyzed visualization elements mainly applied to the representative information services. To find out the relation between attributes of visualization elements and efficiency of information service, we had analyzed attributes of target elements before we have evaluated. Through this study we revealed that Information visualization on information service has to be applied with considering the characteristics of information and each visualization element, and its elements can be optimized and support users to obtain intuitive insight when they are complementally combined and offer sufficient attributes additionally. We expect that the result of this study will be a guide for utilizing information visualization and developing visualization elements.