• Journal of Korea Multimedia Society
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• v.11 no.5
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• pp.685-691
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• 2008

Recently with the rapid evolution of the mobile computing and communication technologies, mobile VOD service becomes increasingly important for wireless mobile users. The VOD service is being widely used in various areas of application, such as education, entertainment and business, because it provides users convenience in easily having access to video information at any time in any places. However, in reality, the mobile system has many difficulties in providing the smooth VOD service owing to frequent transfers and cutoffs of clients. The importance of a technique to transmit broadcasting is being stressed as a method for providing stabler mobile VOD service to a large number of clients. This paper is aimed at showing how to reduce demands for server bandwidth and delay of earlier service through performance analysis by suggesting an effective VOD broadcasting transmission technique through channel division in the mobile atmosphere. Many researches have been made about regular broadcasting techniques in particular. This study divides the methods used for assigning channels which have been decided by the size of segments into a group of regular channels and assistant channels using wireless gap-fillers to provide effective VOD services to a large number of clients at the mobile environment using small bandwidth resources. The regular channels transfer regular streams, while assistant channels repeatedly transfer the first segment to reduce early service delay time to receive regular streams. In this way, the study suggests a technique to reduce server bandwidth demand and early service delay time. Through the proposed technique, the server bandwidth demand could be reduced by more than 30 percent and the study continuously shows reduced early service delay time through conducting performance analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.493-500
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• 2017

Based on the data accumulated through EMU fault management, this paper examines the reliability of old railway car parts and proposes measurements to improve safety. Subway Line 7 of the Seoul Metropolitan Rapid Transit Corporation, auxiliary power unit (Static Inverter) of the EMU second version is a core equipment to supply power to various room-service units in cars and make an effect directly on passenger satisfaction. To analyze the pattern of failure throughout the field data over a long period of time, this analysis of statistics and reliability considers the operating environment and stress factors. This statistical analysis presents the correlation between failure and the temperature stress factors related to frequent failure occurring intensively in summer. In addition, throughout the analysis of the life of the IGBT inverter, the effect of the temperature stress factor was observed before and after the repair. As a result of an analysis of the optimal operating conditions considering two variations of EMU, such as variable load and outside temperature, a difference in the cooling capacity between the optimal operating conditions and frequent failure conditions was observed. Based on this analysis, this paper suggests a way to minimize cooling capacity difference for the optimal operational conditions.

• Korean Security Journal
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• no.49
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• pp.187-214
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• 2016

In the mordern society, the reliance on the cyber domain and the cyber connectivity has been increasingly strengthened. Due to this phenomenon, the cyberterror against critical infrastructures and state organs might lead to fatal consequences. Lately, North Korea's cyberattacks against South Korea's national organizations and financial computer networks are becoming more and more intelligent and sophisticated. The cyberattacks against such critical infrastructures have caused enormous economic loss and social disorder. This paper is designed to examine comparatively the cyberterror related laws and organizations of the advanced countries such as U.S. and U.K. and to draw implications. Although those countries are under different institutional and cultural backgrounds with varying security envrionments, they are identically pursuing measures by establishing government-wide counterterror system for coordination and cooperation. They are also commonly focusing upon creating new organizations equipped with new system and upon enhancing intelligence performance and devising punishment regulations. Korea is lack of framework laws regulating cyber security, having only scattered individual laws. Since such legal base is far from efficient counterterror activities, it is necessary that the legal and policy response of the advanced countries should be closely studied for selective introduction. That will eventually lead to legislation of cyber security law. With such legislation on hand, it is subsequently required to strengthen crisis management for prevention of cyberterror and to create joint response team, cooperating with private organizations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.835-842
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• 2009

DVB-SSP is a new broadcasting system for hybrid satellite communications, which supports mobile handheld systems and fixed terrestrial systems. However, a critical factor must be considered in upper layer decoding which including erasure Reed-Solomon error correction combined with cyclic redundancy check. If there is only one bit error in an IP packet, the entire IP packet is considered as unreliable bytes, even if it contains correct bytes. IF, for example, there is one real byte error, in an If packet of 512 bytes, 511 correct bytes are erased from the frame. Therefore, this paper proposed two kinds of upper layer decoding methods; LLR-based decoding and hybrid decoding. By means of simulation we show that the performance of the proposed decoding algorithm is superior to that of the conventional one.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.251-261
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• 2019

The importance of autonomous driving systems that utilize V2X services such as V2V(Vehicle to Vehicle) and V2I(Vehicle to Infrastructure) for safer and more comfortable driving is increasing with the recent development of autonomous vehicles. Partly autonomous vehicles based on environmental sensors have limitations for predicting and determining areas beyond the recognition distance of the mounted sensors and in response to atypical objects that are difficult to detect. Therefore, it is important to utilize the V2X service to improve the limit of sensor detection performance and to make driving safer and more comfortable. However, there may be an accident risk of autonomous vehicles due to incorrect information provided by V2X. Thus, the application of technology to prevent this needs to be considered. In this pater, we used the ISO-26262 Part3 Process and performed HARA (Hazard Analysis and Risk Assessment) to derive the risk sources of autonomous vehicles due to V2I malfunctions by using the communication between vehicles and infrastructure among V2X. We also developed ASIL ratings based on the simulations and real vehicle tests of the malfunctions of major cases of usnig V2I.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2004.01a
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• pp.1-226
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• 2004

I. Title APMC'03(2003 Asia Pacific Microwave Conference) II. Objecuve $\bigcirc$Investigation of new trend in the field of microwave engineering $\bigcirc$Establishment of R＆D track for wireless and high speed communication III. Scope of investigation $\bigcirc$R＆D trend in various microwave engineering areas-Solid state Devices and circuits-Electromagnetic Field Theory-EMI＆EMC-Phased ＆ Active Array Antennas-Scattering ＆ Propagation $\bigcirc$Discussions with various technical topics-New research ＆ development topics-Establishment of wireless ＆ high speed communications IV. Results During the conference, very active academic exchange were possible between Korean and foreign microwave engineering scholars. It was also possible to introduce the level and activities of Korean microwave engineering researches to foreign countries. Also, it was good opportunity to contact foreign scholars and researchers for valuable academic discussion using technical paper presentations and inquiries.

• KOMUNHWA
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• no.68
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• pp.25-39
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• 2006

This article attempts to define identity, role and functions of a university museum and to suggest specialization of the university museum in the perspective of culture, arts, and science. A university museum is defined as a center for the service of the university community and its development which acquires, researches, communicates, exhibits and educates, for purposes of eduinfotainment,29 material evidence of people and their environment. The target user of the today's university museum are not only professors, students, university workers, but also university neighbourhood such as the related professionals, patrons, parents, school children and villagers. A multi-dimensional and multi-purpose university museum can be established and managed in a real world and / or a cyber world in the perspective of culture, arts, and science. Based on a ubiquitous system30 in a cyber world vis-a-vie a real world, the university museum can be easily utilized by users anywhere, anytime and any device. In order to specialize the university museum in the perspective of culture, arts and science, it is desirable that the university museum director with the CEO of the university community promote the specialization of the university museum based on philosophy and strategies of university community management after they definitely evaluate the components and resources of the university museum such as human powers, museum collections, organizational, technological, capital, spacial and symbolic resources, The specialization of the university museum should be projected and executed in the direction of maintaining the typical scope of museum activities and managing the effective museum management. Specializing the university museum in the perspective of culture, arts, and science can contribute not only to establish the identity of the university community and to perform role and functions of the university museum but also to encourage academic development, to revaluate the brand of the university community and to promote the marketing for the university.

• Spatial Information Research
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• v.22 no.1
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• pp.75-84
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• 2014

Power lines are one of the main obstacles causing an aircraft crash and thus their realtime detection is significantly important during flight. To avoid such flight obstacles, the use of LIDAR has been recently increasing thanks to its advantages that it is less sensitive to weather conditions and can operate in day and night. In this study, we suggest a fast method to detect power lines from LIDAR data for flight obstacle avoidance. The proposed method first extracts non-ground points by eliminating the points reflected from ground surfaces using a filtering process. Second, we calculate the eigenvalues for the covariance matrix from the coordinates of the generated non-ground points and obtain the ratio of eigenvalues. Based on the ratio of eigenvalues, we can classify the points on a linear structure. Finally, among them, we select the points forming horizontally long straight as power-line points. To verify the algorithm, we used both real and simulated data as the input data. From the experimental results, it is shown that the average detection rate and time are 80% and 0.2 second, respectively. If we would improve the method based on the experiment results from the various flight scenario, it will be effectively utilized for a flight obstacle avoidance system.

• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.27-35
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• 2007

When sensor networks are deployed in open environments, all the sensor nodes are vulnerable to physical threat. An attacker can physically capture a sensor node and obtain the security information including the keys used for data authentication. An attacker can easily inject false reports into the sensor network through the compromised node. False report can lead to not only false alarms but also the depletion of limited energy resource in battery powered sensor networks. To overcome this threat, Fan Ye et al. proposed that statistical on-route filtering scheme(SEF) can do verify the false report during the forwarding process. In this scheme, the choice of a security threshold value is important since it trades off detection power and energy, where security threshold value is the number of message authentication code for verification of false report. In this paper, we propose a fuzzy rule-based system for security threshold determination that can conserve energy, while it provides sufficient detection power in the SEF based sensor networks. The fuzzy logic determines a security threshold by considering the probability of a node having non-compromised keys, the number of compromised partitions, and the remaining energy of nodes. The fuzzy based threshold value can conserve energy, while it provides sufficient detection power.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.1
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• pp.25-31
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• 2012

The frequency and abundance of jellyfish, presumably related with climate change, fisheries overexploitation, marine pollution including land reclamation and dyke construction, are increasing worldwide. This feature has attracted interest and concerns from general public and public officials, and government is seeking how the damages could be prevented or reduced down. Korean government, having recent huge blooms of jellyfish, engaged in reducing and/or countermeasuring jellyfish damages. Korean research themes include ecology and physiology of blooming jellyfish species, understanding of the blooming mechanism, and focus on the eradication of blooming jellyfish, without governmental integrative management plan. EU is undertaking scientific projects focused on understanding of the mechanism and control of jellyfish blooms, and establishment of an integrative management. In USA, government has established the code on jellyfish management for conserving and protecting the fish and shellfish resources and one of its department is specially assigned to monitor jellyfish appearance, undertake research, and prepare management plan. Japan also assigned a department and research institute for jellyfish research. Their main interest is to predict jellyfish drifting and mass bloom. Compared to Korea, USA, EU and Japan emphasize integrative management that includes ecological understanding, public education and outreaches, communication and control, if possible, of jellyfish blooms, based on scientific data. We suggest then, 1) establishment of an integrative scientific system consisting of policy and scientific experts to prepare inter-ministrial integrative management plan to effectively combat jellyfish blooms and to maximize the scientific result; 2) concept change from harmful to exploitable marine animal in policy making and research; and 3) active education and information service for people. We expect that these suggestions can be useful for jellyfish management and policy making on another harmful marine organisms.