• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.2B
• /
• pp.162-169
• /
• 2009

Message Authentication Code (MAC) assures integrity of messages. In Mobile WiMAX, 128-bit Cipher-based MAC (CMAC) is calculated for management messages but only the least significant half is actually used truncating the most significant 64 bits. Naming these unused most significant 64bits Shared Authentication Information (SAI), we suggest that SAI can be applied to protect the network from DDoS attack which exploits idle mode vulnerabilities. Since SAI is the unused half of CMAC, it is as secure as 64bits of CMAC and no additional calculations are needed to obtain it. Moreover, SAI doesn't have to be exchanged through air interface and shared only among MS, BS, and ASN Gateway. With these good properties, SAI can efficiently reduce the overheads of BS and ASN GW under the DDoS attack.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.1 no.2
• /
• pp.145-158
• /
• 1997

Method for synchronizing multimedia data is needed to support continuous transmission of multimedia data through a network in a bounded time and it also required for supporting continuous presentation of multimedia data with the required norminal playout rate in distributed network environments. This paper describes a new synchronization method for supporting delay-sensitive multimedia Presentation without degration of Quality of services of multimedia application. It mainly aims to support both intermedia and intermedia synchronization by absorbing network variations which may cause skew or jitter. In order to remove asynchonization problems, we make use of logical time system, dynamic buffer control method, and adjusting synchronization intervals based on the quality of services of a multimedia. It might be more suitable for working on distribute[1 multimedia systems where the network delay variation is changed from time to time and no global clock is supported. And it also can effectively reduce the amount of buffer requirements needed for transfering multimedia data between source and destination system by adjusting synchronization intervals with acceptable packet delay limits and packet loss rates.

• Smart Media Journal
• /
• v.8 no.3
• /
• pp.41-46
• /
• 2019

In a MMORPG, a typical application of virtual environment systems, it is a common desire to play in a more realistic environment. However, it is very difficult to provide a latency-free virtual environment to a large user base, mainly due to the fact that the real environment must be configured on multiple servers rather than on single server and that data must be shared on the real server when users move from one region to another. Experiencing response delays continuously in the process of information synchronization between servers greatly deteriorates the degree of immersion. In order to solve this problem, it is necessary to minimize the response delay occurring in the information synchronization process between the servers. In this paper, we propose Migration Agent for efficient information synchronization between field servers providing information of virtual environment and minimizing response delay between Field Server and PC(Player Character) and implement it in cloud computing network. In the proposed system, CPU utilization of field server increased by 6 ~ 13%, and response time decreased by 5 ~ 10 seconds over the existing system in 70,000 ~ 90,000 PCs

• Industry Promotion Research
• /
• v.9 no.2
• /
• pp.45-58
• /
• 2024

This study modelled the social network structure characteristics between Innopolis Start-ups located in Daejeon and Innopolis Start-ups' customers scattered across the country as a tendency of regional clustering among homogeneous technologies, and the observed values were included within the 95% confidence interval of the ERGM(Exponential Random Graph Model) analysis model. If both the research institute and the customer company are located in Yuseong-gu, Daejeon, the probability of being connected is about 13 times higher than if they are located in other administrative districts, and there is a strong tendency of connection between firms with the same technology with a negative value of assortment and homogeneity (0.1904), especially among the six technology sectors, with a P value of 0.035. There was a negative value (-0.0035) among firms not located in Yuseong-gu, with less clustering tendency. This confirms that Yuseong-gu, Daejeon, where the Daedeok Innopolis is located, is forming the centre of an innovation cluster.

• Journal of KIISE:Information Networking
• /
• v.34 no.5
• /
• pp.348-359
• /
• 2007

The conventional mobile VPN services assumed the mobile communications occur between the MN in foreign networks and the CN in the home network. However, if a MN wants to communicate with another MN in a foreign network, it could degrade the performance of the mobile VPN service because of the triangular routing problem. In this paper, we propose a route optimization mechanism based on the mobile VPN using an x-HA allocated by diameter MIP in order to support the efficient communication between the mobile VPN users in foreign networks. The i-HA maintains the VPN-TIA as well as the x-HoA as the CoAs to solve the security problem and to provide an efficient route optimization simultaneously. Moreover, we proposed revised IPSec tunnel configuration to reduce the IPSec tunnel overheads at a MN when the MN communicates with several MNs in the foreign networks at the same time. The VPN server, a security management entity in the home network, notifies an additional IPSec tunnel establishment between the x-HAs where the communication peers are registered. The simulation result showed that the proposed scheme decreases the end-to-end packet delay time and improves the throughput after the handoff compared to the existing mechanism.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.7
• /
• pp.613-621
• /
• 2016

This research connected network equipment, including CCTV, PAGA, IP-PBX, and Legacy, in order to enable the operation and configuration of internal IP-based network equipment in maritime plants and vessels, both in the field and from remote places, and to allow for the support of remotely controlling such equipment. It also realized an operating program for the integrated network equipment management system to enable the monitoring and control of equipment status, operation condition, and notifications from distant places. By applying the operating program to satellite stations and vessels sailing on the sea, a performance test was conducted to evaluate data loss and transmission/reception delay in the communication section between the land and vessels. As a result, this research verified the normal operation of CCTV control and of real-time monitoring and control of the network equipment, including PAGA, IP-PBX, and Legacy under the FBB and MVSAT environments. It was observed that the transmission of CCTV video images with a large volume of data as well as the transmission and reception of voice data were found to be slightly delayed, indicating the need to develop technology to compress and convert data for real-time transmission and reception.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.496-500
• /
• 2009

소하천은 하천 네트워크의 최상류에 넓게 소재하는 하천이다. 본 연구의 목적은 올바른 소하천 수생태계 관리방안을 도출하기 위하여 소하천의 건강성을 분석하고 현행 소하천 관리제도의 개선점을 모색하는 것이었다. 본 연구에서는 다음과 같은 분석방법을 이용하였다. 첫째, 2007년 한강수계 소하천 28개 지점에서의 부착조류($DAI_{PO}$, TDI), 저서성 대형무척추동물(KSI), 어류(IBI), 서식환경, 수변환경 등 6개 항목에 대한 수생태 건강성 조사결과를 토대로 공간적 분포와 수질현황을 조사하여 소하천에 대한 종합적인 건강성 평가를 실시하였다. 둘째, 분석대상지역을 각각 소하천 구간스케일(28개 지점)과 유역스케일(팔당호, 안성천 유역)로 선정, 하천차수도(1:25,000)를 활용하여 해당 구간과 유역의 소하천도를 작성하였다. 셋째, 작성된 소하천도 는ArcGIS(ver. 9.3)에서 30, 60, 90, 120, 150-m Buffering을 하였다. 다음으로 소하천 구간은 중분류(23개 항목, $2000{\sim}2006$ 또는 2007년) 토지피복도를, 팔당호 및 안성천 유역의 소하천은 대분류(8개 항목, $1975{\sim}2000$년) 토지피복도를 적용하여 분류항목별 면적변화비율을 산정하였다. 끝으로 소하천 정비에 대한 제도적 문제점을 분석하여 소하천 관리의 개선점을 연구하였다. 그 연구 결과, 첫째 연구대상 소하천(28개)의 건강성은 도심 소하천에서 가장 낮게 조사되었고, 일부 소하천은 비록 상류에 위치함에도 불구하고 부착조류의 유기물, 영양염류 평가가 낮게 평가되었다. 둘째, 소하천 구간 스케일의 수변토지피복변화 분석결과 소하천 수생태 건강성은 거시적으로 산림, 도시화, 밭 등의 피복변화에 민감한 것으로 나타났으며 도시화 피복변화의 영향은 수변 30m에서 60m보다 3배 정도 큰 것으로 나타났다. 유역 스케일 분석에서는 상대적으로 도시화가 많이 진행된 안성천 유역의 소하천이 팔당호 유역보다 낮은 건강성일 것으로 예측되었다. 결론적으로 적절한 소하천 수변관리는 지역 하천의 건강성을 온전히 회복시키고 개선 유지하기 위한 중요한 수단들 중에 하나이며 수변토지피복의 변화율은 (소)하천 건강성 또는 유역관리의 지표로 활용될 수가 있는 것으로 조사되었다. 이와 더불어 본 연구를 통해 소하천 복원 및 관리는 소하천 특성을 고려한 장기적인 계획과 관리대상의 우선순위를 바탕으로 점진적인 대안마련이 필요할 것으로 사료된다.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.16 no.6
• /
• pp.182-194
• /
• 2017

Most of the drone (Unmanned Aerial Vehicle) research in terms of traffic management involves detecting and tracking roads or vehicles. The purpose of analyzing image footage in the transportation sector is to overcome the limitations of the existing traffic data collection system (vehicle detectors, DSRC, etc.). With regards to this, drones are the good alternatives. However, due to limitation in their maximum flight time, they are appropriate to use as a complementary rather than replacing the existing collection system. Therefore, further research is needed for utilizing drones for transportation analysis purpose. Traffic problems often arise from one particular section or a point that expands to the whole road network and drones can be fully utilized to analyze these particular sections. Based on the study on the uses of traffic survey analysis, this study is conducted by extracting traffic flow parameters from video images(range 800~1000m) of highway unit segments that were taken by drones. In addition, video images were taken at a high altitude with the development of imaging technologies.

• Journal of the Korean Geotechnical Society
• /
• v.39 no.10
• /
• pp.41-48
• /
• 2023

The presence of abnormalities in the subgrade of roads poses safety risks to users and results in significant maintenance costs. In this study, we aimed to experimentally evaluate the temperature distributions in abnormal areas of subgrade materials using infrared cameras and analyze the data with machine learning techniques. The experimental site was configured as a cubic shape measuring 50 cm in width, length, and depth, with abnormal areas designated for water and air. Concrete blocks covered the upper part of the site to simulate the pavement layer. Temperature distribution was monitored over 23 h, from 4 PM to 3 PM the following day, resulting in image data and numerical temperature values extracted from the middle of the abnormal area. The temperature difference between the maximum and minimum values measured 34.8℃ for water, 34.2℃ for air, and 28.6℃ for the original subgrade. To classify conditions in the measured images, we employed the image analysis method of a convolutional neural network (CNN), utilizing ResNet-101 and SqueezeNet networks. The classification accuracies of ResNet-101 for water, air, and the original subgrade were 70%, 50%, and 80%, respectively. SqueezeNet achieved classification accuracies of 60% for water, 30% for air, and 70% for the original subgrade. This study highlights the effectiveness of CNN algorithms in analyzing subgrade properties and predicting subsurface conditions.

• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10a
• /
• pp.178-180
• /
• 1998

분산 파일 시스템에서는 파일 서버는 사용률이 높고, 통신 네트워크나 클라이언트 워크스테이션은 상대적으로 낮은 것으로 보고 하고 있다. 따라서, 시스템의 확장은 파일 서버가 처리해야 할 작업 부담을 증가하는 결과를 초래하므로 파일 서버는 시스템 사의 주된 병목 구간이 된다. 따라서 분산 시스템의 성능을 향상시키기 위해서는 파일 서버의 작업 부담을 클리언트로 이전시키고 가급적이면 파일 서버가 유지되는 상태 정보의 양을 줄여야 한다. 본 논문에서는 파일 서버에서 유지되는 상태 정보의 양이 파일 서버의 작업 부담에 비례한다는 가정 하에 파일 서버의 작업부담을 클라이언트들에게 이양시키는 대리인에 의한 캐쉬 일관성 유지 방식과 클라이언트들간의 상호 협조를 통해 요구된 파일에 대한 응답시간을 줄이는 방안을 제안하였다.