• The Journal of Korean Institute of Communications and Information Sciences
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• 제40권1호
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• pp.96-107
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• 2015

VANET technologies provide real-time traffic information for mitigating traffic jam and preventing traffic accidents, as well as in-vehicle infotainment service through Telematics/Intelligent Transportation System (ITS). Due to the rapid increasement of various requirements, the vehicle communication with a limited resource and the fixed frame architecture of the conventional techniques is limited to provide an efficient communication service. Therefore, a new flexible operation depending on the surrounding situation information is required that needs an adaptive design of the network architecture and protocol for efficiently predicting, distributing and sharing the context-aware information. In this paper, Vehicle-to-Infrastructure (V2I) based on communication between vehicle and a Road Side Units (RSU) and Vehicle-to-Vehicle (V2V) based on communication between vehicles are effectively combined in a new MAC architecture and V2I and V2V vehicles collaborate in management. As a result, many vehicles and RSU can use more efficiently the resource and send data rapidly. The simulation results show that the proposed method can achieve high resource utilization in accordance. Also we can find out the optimal transmission relay time and 2nd relay vehicle selection probability value to spread out V2V/V2I collaborative schedule message rapidly.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제37C권12호
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• pp.1310-1317
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• 2012

The Global Navigation Satellite System (GNSS) like US Global Positioning System (GPS) and EU Galileo are based on providing precise time and frequency synchronized ranging signals. Because of the exploitation of very precise timing signals these GNSS are used to provide both navigation and time distribution services. Moreover, because the positioning accuracy will improve as more satellites become available, we should expect that a combination of Galileo and GPS will provide better performance than those of both systems separately. However, Galileo will not use the same time reference as GPS and thus, a time difference arises - the GPS-Galileo Time Offset (GGTO). The navigation solution calculated by receivers using signals from both navigation systems will consequently contain a supplementary error if the GGTO is not accounted for. In this paper, we compared GPS Time (GPST) with Galileo Sytem Time (GST) and analyzed the effects of GGTO on positioning accuracy by simulation test. And then we also analyzed the characteristics of two representative GGTO correction methods such as the navigation message based method at system level and the estimation method at user level and propose the conceptual design of the novel correction method being capable of preventing previous method's problems.

• The KIPS Transactions:PartC
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• 제16C권3호
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• pp.285-298
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• 2009

According to the development of ubiquitous technologies, sensor networks is used in various area. In particular, medical field is one of the significant application areas using sensor networks, and recently it has come to be more important according to standardization of the body sensor networks technology. There are special characteristics of their own for medical sensor networks, which are different from the one of sensor networks for general application or environment. In this paper, we propose a hierarchical medical sensor networks structure considering own properties of medical applications, and also introduce transmission mechanism based on hierarchical structure. Our mechanism uses the priority and threshold value for medical sensor nodes considering patient's needs and health condition. Through this way Cluster head can transmit emergency data to the Base station rapidly. We also present the new key establishment mechanism based on key management mechanism which is proposed by L. Eschenauer and V. Gligor for our proposed structure and transmission mechanism. We use key provisioning for emergency nodes that have high priority based on patients' health condition. This mechanism guarantees the emergency nodes to establish the key and transmit the urgent message to the new cluster head more rapidly through preparing key establishment with key provisioning. We analyze the efficiency of our mechanism through comparing the amount of traffic and energy consumption with analysis and simulation with QualNet simulator. We also implemented our key management mechanism on TmoteSKY sensor board using TinyOS 2.0 and through this experiments we proved that the new mechanism could be actually utilized in network design.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제17권9호
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• pp.12-20
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• 2016

With the enhancements in existing major industries, cloud computing-based converging services have been created, as well as value-added industries. A variety of converging services are now provided, from personalized services up to industrial services. In Korea, they have become the driving force behind existing industries throughout the whole economy, but mainly in finance, mobile systems, social computing, and home services, based on cloud services. However, not only denial of service (DOS) and distributed DOS (DDOS) attacks have occurred, but also attack techniques targeting core data in storage servers. Even security threats that are hardly detected, such as multiple attacks on a certain target, APT, and backdoor penetration have also occurred. To supplement defenses against these, in this article, a protocol for authority management is designed to provide users with safe storage services. This protocol was studied in cases of integration between a cloud environment and big data-based technology, security threats, and their requirements. Also studied were amalgamation examples and their requirements in technology-based cloud environments and big data. With the protocol suggested, based on this, security was analyzed for attack techniques that occur in the existing cloud environment, as well as big data-based techniques, in order to find improvements in session key development of approximately 55%.

• Journal of Distribution Science
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• 제14권4호
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• pp.55-66
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• 2016

Purpose - This article aims to explore the characteristics of disaster risk distribution information in China. Also, this research attempts to analyze the findings of risk communication using case study in chronological order in terms of social amplification of risk. To achieve the purpose, the paper reviews the trends and issues of risk communication in China, with an emphasis on examining earthquakes by a chronological approach. In these regards, we hope that some relevant findings from this empirical study with cases will be able to enhance national risk communication and provide implications in Korea as well. Research design, data, and methodology - The conceptual framework of this study is theoretically based on the risk amplification model, which describes signals about risk transmitted and processed by individuals and social groups. The social amplification of risk also reflects the interactions of social groups about disaster-related risk issues, which are potential amplifiers or attenuators of communication signals. The key concept of social amplification implies that the risks pertaining to natural disasters interact with social, psychological, institutional, and cultural processes in ways that can affect public perceptions of risk. SMCRE Model is methodologically employed to examine risk communication history of China with the focus on natural disaster. Four earthquakes are selected to figure out the chronological characteristics of risk communication since 1970s. He bei Tang Shan earthquake is selected as an example disaster before 1990's, while the earthquake in Yun Nan Jiang is explored for the case study of 1990's. The earthquake in Si Chuan Wen Chuan is also examined as a example disaster of 2000's. The recent earthquake in Si Chuan Ya An Lu Shan is selected as a case of 2010s. Results - SMCRE model in this case study is operationally defined as a methodology and applied to the four earthquakes occurred in China. SMCRE model describes the exchange of risk information and is also applied to all forms of communication between stake holders. Each factor of risk communication includes source, message, channel, receiver and effect. It is notable that a big progress has been made on disaster risk communication in China for the past 40 years. We also found that highly developed information technology has enabled Chinese society to better cope with natural disaster, leading to enhanced disaster risk communication. It is mainly found from case study that the disaster risk communication of China has been involved with political situation, which derived from the change of government for the past 40 years. Conclusion - From this historical research, it can be inferred that the policies and politics of Chinese leaders have had a more critical role to play in the process of source of risk communication than those of any other countries. The results of this paper also support that the effective risk communication involves not only the improved reliability of local government as a key factor of disaster risk communication, but also is accompanied by international cooperation for substantial collaboration with stake holders.

• Journal of Broadcast Engineering
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• 제24권5호
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• pp.849-858
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• 2019

Recent developments in computer graphics technology and image processing technology have increased interest in point cloud technology for inputting real space and object information as three-dimensional data. In particular, point cloud technology can accurately provide spatial information, and has attracted a great deal of interest in the field of autonomous vehicles and AR (Augmented Reality)/VR (Virtual Reality). However, in order to provide users with 3D point cloud contents that require more data than conventional 2D images, various technology developments are required. In order to solve these problems, an international standardization organization, MPEG(Moving Picture Experts Group), is in the process of discussing efficient compression and transmission schemes. In this paper, we provide a region division transfer method of 3D point cloud content through extension of existing MPEG-DASH (Dynamic Adaptive Streaming over HTTP)-SRD (Spatial Relationship Description) technology, quality parameters are further defined in the signaling message so that the quality parameters can be selectively determined according to the user's request. We also design a verification platform for ROUTE (Real Time Object Delivery Over Unidirectional Transport)/DASH based heterogeneous network environment and use the results to validate the proposed technology.

• Journal of the Society of Disaster Information
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• 제15권2호
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• pp.223-238
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• 2019

Purpose: This study aims at exploring implications of discourse and social practice produced by various stakeholders in politics, economy and society to provide useful material for effective disaster response in South Korea. Method: Applying the Critical Discourse Analysis model of Fairclough, this study analyzes the newspaper articles of three domestic press companies mainly about the November 2017 Pohang earthquake. Results: As a result, first, the three media companies point out the low effectiveness of disaster response manuals and evacuation training. Second, strengthening shelter services and expanding support for the victims are important for recovery from the earthquake. Third, to prevent the future damages, they suggest the implementation efforts to improve the seismic design and short message service based disaster alert system. Conclusion: Based on the findings, this study suggests to improve the practicality and effectiveness of disaster prevention measures, establish an organic and integrated disaster response system, emphasize the roles and participation of citizens, check the responsibility of experts, and make the media to form sound discourse on disaster response.

• Journal of Digital Convergence
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• 제17권3호
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• pp.413-425
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• 2019

We see many images every day, some of these images are stored in memory, and the majority are immersed in the unconscious world. Visual elements are seen by personal attention or by visual or biological attention factors. Specific and clear discovery of this visual attention has not yet been made. However, there is an interesting discussion of this visual attention in the fields of interior, design, visual perception, advertising, and psychology. Advertising photographers are expected to produce what their work will have on viewers and consumers. However, the adjustment of subject, exposure, color, or post-production, which could have a visual effect on the consumer, was determined only by the photographer's senses rather than the experimental verification. The advertisement photographs provide a specific image related to the object to be advertised and deliver a certain message. Therefore, it is necessary to understand the effect of the image in a certain visual way. According to previous studies, there are two major factors that affect the visual impression of the viewer. One is the factor depending on the type and content of the subject and the other is the factor about the density and color of the subject. The purpose of this study is to investigate the meaningful changes in the visual perception depending on the shape, content, color and tone of the subject, which can be called the main subject, And to analyze the effects of I will study some implications of visual elements through various analyzes.

• KIPS Transactions on Software and Data Engineering
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• 제8권8호
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• pp.317-322
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• 2019

Programming judge systems for programming training support are typically built on the Web, where the examiners uploads a programming problem, which the student reads and submits an answer to the problem. The judge system executes the submitted answer of source code to provide feedback such as pass, failure, and error messages. Students who receive the feedback except for the pass continues debugging the source code until they are judged to pass. We developed an online judge system to support programming training and analyzed answers submitted by the students and found that many of the students who were not judged to pass that test did not know exactly where they were wrong but continued to solve the problem. The current judge system generally feeds runtime error messages back to students. However, with only runtime error message, it is difficult for student who train to find the wrong part of the answer. Therefore, in this paper, we propose a system that provides the feedback of programming failure by analyzing the control flow of the test cases used in the source code submitted by the student. The proposed system helps students find the wrong parts more quickly by feeding back the paths where faults in the control flow may exist. In addition, we show that this system is applicable to the answer source code that the actual student submitted.

• Journal of the Korea Convergence Society
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• 제12권4호
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• pp.77-86
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• 2021

This study explored the role of perceived stress in Korean high school students' suicidal thought. In so doing, we also investigated the mediating role of high school students' internet use time and amount of drinking alcohol. For this, 2019 Korean adolescent health behavior survey was used. Complex design multivariage logistic regression analysis revealed that high school students' perceived stresss(OR:5.607, 95%CI:5.077-6.191) and amount of drinking(ranging from OR:1.412, 95%CI:1.159-1.720 to OR:2.325, 95%CI:1.928-2.803) played a significant role in their suicidal thoughts. Internet use time and amount of alcohol consumed were found to play a mediating role. Implications of the results are discussed. Therefore, since internet use mediated suicidal thinking among adolescents, it is necessary to develop a intervention program or message for them.