• 한국정보전자통신기술학회논문지
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• 제11권4호
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• pp.401-407
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• 2018

본 논문에서는 중 장대파 대역 주파수를 사용하는 단축 모노폴 안테나의 전송 대역폭을 해석하고 대역폭에 따른 전송 데이터 용량을 적용한 전송방식을 해석하였다. 아울러 요구 유효방사전력 특성 및 안테나 효율을 고려한 송신 출력 특성을 산출하였다. 전송방식과 송신기 출력 특성 분석을 위하여 중 장대파 대역 안테나 시스템으로 65kHz 대역의 시각정보 전송시스템과 283.5kHz 대역의 위성항법보정시스템을 고려하였으며, 제한된 물리적 안테나 사이트 환경에 설계된 기부 절연형 지선식 안테나를 적용하였다. 적용된 중 장대파 대역 안테나의 방사 특성을 모의 실험하고 안테나 임피던스 특성으로부터 등가회로를 산출하고 안테나 대역폭을 산출하여 모의 실험한 안테나 대역폭과 비교 분석하였다. 아울러, 송신 안테나의 요구 유효방사전력을 위한 중 장대파 대역 송신기 출력 특성을 유도하고, 전송 안테나 대역폭에 따른 중 장대파 대역 전송시스템의 전송방식을 설계하고 제안하였다.

• 디지털산업정보학회논문지
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• 제11권3호
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• pp.69-77
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• 2015

MANET is composed of only the mobile nodes have a limited transmission range. The dynamic topology by the frequent movement of nodes makes routing difficult and is also cause exposed to security vulnerabilities. In this paper, we propose the security routing technique consisted of mechanism of two steps in order to respond effectively to attack by the modification of the routing information and transmit secure data. The hierarchical structure is used and the authentication node that issues the key of the nodes within each cluster is elected in this proposed method. The authentication node manages key issues and issued information for encrypting the routing information from the source node. The reliability value for each node is managed to routing trust table in order to secure data transmission. In the first step, the route discovery is performed using this after the routing information is encrypted using the key issued by the authentication node. In the second step, the average reliability value of the node in the found path is calculated. And the safety of the data transmission is improved after the average reliability value selects the highest path. The improved performance of the proposed method in this paper was confirmed through comparative experiments with CBSR and SEER. It was confirmed a better performance in the transmission delay, the amount of the control packet, and the packet transmission success ratio.

• 한국통신학회논문지
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• 제41권4호
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• pp.433-440
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• 2016

본 논문에서는 사물인터넷 환경에서 통신 기기들이 정보를 직접 공유하고자 할 때 전체 네트워크의 에너지 소모량을 최소화하기 위한 방식을 제안한다. 제안하는 방식은 매 전송 시 동적으로 전송 노드 및 전송 데이터를 선택하는 효과적인 네트워크 부호화 기법을 사용하여 정보 공유에 필요한 총 전송 횟수를 감소시킨다. 실험을 통하여 기존의 고정된 순서로 전송 노드를 설정하는 네트워크 부호화 방식, 랜덤한 순서로 전송 노드를 설정하는 네트워크 부호화 방식, 그리고 랜덤한 순서로 전송 노드를 설정하는 비부호화 방식에 비해 총 전송 횟수 측면에서 보다 뛰어난 성능을 가짐을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권7호
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• pp.3239-3267
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• 2018

Image and video dehazing is a popular topic in the field of computer vision and digital image processing. A fast, optimized dehazing algorithm was recently proposed that enhances contrast and reduces flickering artifacts in a dehazed video sequence by minimizing a cost function that makes transmission values spatially and temporally coherent. However, its fixed-size block partitioning leads to block effects. The temporal cost function also suffers from the temporal non-coherence of newly appearing objects in a scene. Further, the weak edges in a hazy image are not addressed. Hence, a video dehazing algorithm based on well designed spectral clustering is proposed. To avoid block artifacts, the spectral clustering is customized to segment static scenes to ensure the same target has the same transmission value. Assuming that edge images dehazed with optimized transmission values have richer detail than before restoration, an edge intensity function is added to the spatial consistency cost model. Atmospheric light is estimated using a modified quadtree search. Different temporal transmission models are established for newly appearing objects, static backgrounds, and moving objects. The experimental results demonstrate that the new method provides higher dehazing quality and lower time complexity than the previous technique.

• 한국통신학회논문지
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• 제21권9호
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• pp.2328-2340
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• 1996

Until now, the transmission of data for VOD(Video on Demenad) was based on a real time modelling of video data. Markow Modulated Fluid Sources(MMFS) and Markow Modulated Poisson Sources(MMPS) are the most widely used modelling methods. But the charactersitics of the VBR(Variable Bit Rate) signal prevents modelling from actually being "real-time". Also these methods call for the use of large buffers for the abolishment of cell loss. These modelling methods are, of course, useful i case of teleconferences where a real time modelling of video traffic is inevitable, but they are insufficient in cases where the characteristic infomation of video traffic can be obtained beforehand-cases such as VOD. Video data is speial in that if one file is preprocessed all other products can simply be copied from that onepreprocessed file. This characteristic helps reduce the overhead arising from the job of drawing out characteristic information to almost zero. But still, compared to the existing real time modelling method data transmission using characteristic information succeeds in raising the efficiency of data transmission. In tis paper we will outline a method of dta transmission which use the characteristic information of each video stream, and evaluate this method through some experiments.periments.

• Journal of Information Processing Systems
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• 제15권4호
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• pp.724-736
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• 2019

Dynamic thermal rating technology can effectively improve the thermal load capacity of transmission lines. However, its availability is limited by the quantity and high cost of the hardware facilities. This paper proposes a new dynamic thermal rating technology based on global/regional assimilation and prediction system (GRAPES) and geographic information system (GIS). The paper will also explore the method of obtaining any point meteorological data along the transmission line by using GRAPES and GIS, and provide the strategy of extracting and decoding meteorological data. In this paper, the accuracy of numerical weather prediction was verified from the perspective of time and space. Also, the 750-kV transmission line in Shaanxi Province is considered as an example to analyze. The results of the study indicate that dynamic thermal rating based on GRAPES and GIS can fully excavate the line power potential without additional cost on hardware, which saves a lot of investment.

• 정보보호학회논문지
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• 제18권5호
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• pp.171-180
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• 2008

2006년 12월 미국의 민사소송규칙(FRCP) 개정으로 e-discovery(전자증거개시) 제도가 시행되고 있으나, 이 제도는 디지털 증거의 관리와 제출과정에서 발생할 수 있는 과도한 비용과 시간의 낭비와 같은 다양한 문제점들을 가지고 있다. 현재 e-discovery 제도의 국내 도입 논의가 진행되고 있는 상황에서 본 논문에서는 e-discovery의 절차 중 디지털 증거를 소송상대방에게 제출하는 production 단계에서 발생할 수 있는 민감한 자료 유출, 읽기 불가능, 위 변조 및 손상 등과 같은 문제점에 대해 살펴보고, 이 문제점들을 해결하고 비용과 시간의 낭비를 최소화 할 수 있는 안전한 온라인 디지털 증거 전송 시스템을 제안한다.

• 한국통신학회논문지
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• 제24권7A호
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• pp.973-986
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• 1999

본 논문에서는 무선 패킷 데이터 서비스를 효율적으로 지원하기 위해 채널 액세스 메카니즘과 전송 매카니즘으로 구성되는 MAC 프로토콜을 제안하였다. 채널 액세스를 위해 방송채널은 랜덤 액세스 채널의 상태정보를 알려주고, 이동단말은 상태정보를 기반으로 랜덤액세스를 시도한다. 또한, 이동단말에 액세스 확률을 부여함으로서 랜덤 액세스 채널에서의 short 메시지 전송으로 인한 충돌증가를 방지하였다. 효율적인 전송을 위해 이동단말의 전송대기 큐의 상태에 따라 전송속도를 변경함으로서 버스트한 트래픽 특성에 적응할 수 있도록 하였다. 전송대역과 전송코드 수가 제한된 환경에서 제안한 MAC 프로토콜은 cdma2000 시스템 보다 효과적으로 전송을 지원함을 알 수 있었다.

• Journal of Communications and Networks
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• 제11권3호
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• pp.279-286
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• 2009

This paper proposes an adaptive mode switching algorithm between two strategies in multiple antenna cellular networks:A single-user mode and a multi-user mode for the broadcast channel. If full channel state information is available at the base station, it is known that a multi user transmission strategy would outperform all single-user transmission strategies. In the absence of full side information, it is unclear what the capacity achieving method is, and thus there are few criteria to decide which of the myriad possible methods performs best given a system configuration. We compare a single user transmission and a multi user transmission with linear receivers in this paper where the transmitter and the receivers have multiple antennas, and find that neither strategy dom inates the other. There is instead a transition point between the two strategies. Then, the mode switching point is determined both ana lytically and numerically for a multiple antenna cellular downlink with correlation between transmit antennas.

• International Journal of Internet, Broadcasting and Communication
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• 제9권2호
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• pp.64-69
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• 2017

The abstract should summarize the contents of the paper and written below the author information. Use th In Wide-area Wireless Sensor Networks, network lifetime is short due to energy consumption due to transmission distance. To improve this, we divide the sensor field into layers and reduce transmission distance through multi-hop transmission. However, there is a problem in that the transmission rate drops because there is no Cluster Head in the layer, or the transmission distance increases due to the layer, and energy is wasted. There are DL-LEACH and EDL-LEACH as Protocols to improve this. DL-LEACH uses either single-hop transmission or multi-hop transmission depending on the situation. As a result, the transmission distance is optimized, thereby reducing energy consumption. In case of EDL-LEACH, it is proposed to improve the data rate in DL-LEACH. It is the same as DL-LEACH, but the Cluster Head is mandatory for all layers to improve the transmission rate. Although there is no Cluster Head for each layer, the transmission rate is improved, but the network life is shortened. In this paper, we try to improve the network lifetime while maintaining the EDL-LEACH transmission rate. The shortened network lifetime is due to Cluster Head overload near the base station. To improve this, the Cluster Head distribution method is improved and the network lifetime is improved.