• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.686-688
• /
• 2010

The supply of context information is increasing with the propagation of ubiquitous computing environment. Recently, as context information is being collected through electronic tags and sensors attached to the environment, we need methods to efficiently store and search large volumes of data. This paper describes the application of the RLE (Run Length Encoding) compression method for sensors that continuously collect data in USN/RFID terminals.Time information is marked on the data and one data block is generated and saved. This paper proposes a storage method that allows us to quickly search data of the desired time and place by recording time information in continuous data.

• Journal of Advanced Navigation Technology
• /
• v.10 no.4
• /
• pp.400-405
• /
• 2006

In this paper, we propose a moving object tracking algorithm by using motion estimation in UAV(Unmanned Aerial Vehicle) video. Proposed algorithm is based on generation of initial image from detected reference image, and tracking of moving object under the time-varying image. With a series of this procedure, tracking process is stable even when the UAV camera sways by correcting position of moving object, and tracking time is relatively reduced. A block matching algorithm is also utilized to determine the similarity between reference image and moving object. An experimental result shows that our proposed algorithm is better than the existing full search algorithm.

• Proceedings of the Korean Information Science Society Conference
• /
• 2011.06d
• /
• pp.86-89
• /
• 2011

현재 인터넷이 생활의 일부로 자리함으로써 인터넷을 통해 수많은 멀티미디어의 교환이 발생하며, 많은 멀티미디어 서비스가 이루어지고 있다. 멀티미디어 서비스를 제공함에 있어 최근 저작권 관리 및 보호의 필요성이 대두되고 있다. 이에 따라 멀티미디어 데이터에 대한 암호기술 개발에 많은 연구가 진행되고 있으며 카오스 사상에 기반 한 암호화 연구가 최근 연구 추세이다. 본 논문은 MPEG(Moving Picture Experts Group) 인코딩 과정에서 1차원 카오스 사상(Map)을 이용하여 인트라 블록을 암호화하는 새로운 방법을 제안하고자 한다. 본 제안 시스템은 MPEG 구조 기반으로 CKD(Chaotic Key Distributor)를 이용하여 확장된 키 값으로 인트라 블록의 0이 아닌 DCT(Discrete Cosine Transform) 계수를 암호화 하는 방법이다. MPEG 인코딩 과정중 DCT 계수는 양자화를 통해 손실이 발생하더라도 비교적 많은 0값을 생성한다. 이는 RLE(Run Length Encoding) 과정에서 압축 효과를 높일 수 있다. 제안하는 방법은 영상 손실을 감수하고 수행한 양자화 과정의 효과를 유지하기 위하여 0이 아닌 DCT 계수만을 암호화 한다. 실험 결과 원본과 암호화된 MPEG의 크기의 변화는 매우 적으며, 인코딩 시간 또한 큰 차이를 보이지 않았다.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.49 no.1
• /
• pp.29-38
• /
• 2012

Due to the rapid development of network environment and wireless communication technology, the distribution of digital video has made easily and the importance of the protection for digital video has been increased. This paper proposes the digital video encryption system based on multiple chaos maps for MPEG-2 video encoding process. The proposed method generates secret hash key of having 128-bit characteristics from hash chain using Tent map as a basic block and generates $8{\times}8$ lattice cipher by applying this hash key to Logistic map and Henon map. The method can reduce the encryption overhead by doing selective XOR operations between $8{\times}8$ lattice cipher and some coefficient of low frequency in DCT block and it provides simple and randomness characteristic because it uses the architecture of combining chaos maps. Experimental results show that PSNR of the proposed method is less than or equal to 12 dB with respect to encrypted video, the time change ratio, compression ratio of the proposed method are 2%, 0.4%, respectively so that it provides good performance in visual security and can be applied in real time.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.7
• /
• pp.93-101
• /
• 2020

Regional CRL(certificate revocation list) in vehicular communications is to partition Full CRL into several small CRLs according to geographic location to keep the size of individual CRLs with smaller. However, since a Regional CRL includes vehicle's revoked certificates within its administrative region, it has to know vehicle' location. For this, how to know vehicle' location effectively corresponding to every region represents a major challenge. This paper proposes a Regional CRL scheme which is envisioned to achieve vehicle's location and to make regional CRLs according to vehicles current location efficiently. The scheme is based on the short-lived pseudonyms defined by WAVE standard. It also acquires issued pseudonyms, vehicle's id and region information whenever a vehicle initiates pseudonyms refill after that, utilizes them to create and distribute the Regional CRL. To keep location privacy-preserving for vehicles, the scheme uses the blockchain technology in the network. The analysis results show that it reduces CRL size and database query time for finding revoked certificates sharply in the vehicle's on-board unit.

• The KIPS Transactions:PartD
• /
• v.13D no.3 s.106
• /
• pp.399-404
• /
• 2006

A real-time system is used for various systems from small embedded systems to distributed enterprise systems. Because it has a characteristic that provides a service on time, developers should make efforts to keep this property about time when developing real-time applications. As the result of research about real-time system indicates, TMO model supports various functions for time processing according to the real-time concept. And it guarantees response time which developers defined. So developers need a point of reference to define deadline and check the correctness of time. This paper proposes an improved PS-Block as an infrastructure of analysis tools for TMO to present a point of reference. There is a problem that the existing PS-Block has overhead caused by a policy making duplicated blocks. As such, this paper implements a PS-Block Timing Model to reduce the overhead due to block duplication, and defines a base class for searching in PS-Block. The PS-Block Timing Model, using an improved PS-Block structure, offers a point of reference of deadline and an infrastructure of execution time analysis according to the PS-Block configuration policy. Therefore, TMO developers can easily verify deadline of real-time methods, and improve reliability, and reduce development terms.

• Proceedings of the Korean Information Science Society Conference
• /
• 2007.10b
• /
• pp.296-301
• /
• 2007

본 논문은 낸드 플래쉬 디바이스의 고질적인 문제인 마운트 지연시간을 바이트 접근성을 가지는 비휘발성 저장소자를 이용하여 해결하는 기법을 다룬다. 낸드 플래쉬 디바이스를 사용하기 위해서는, 마운트시에 낸드 플래쉬 디바이스의 전 영역에 걸쳐 분산되어 저장되어 있는 메타 데이터를 스캔하여, 해당 파일 시스템 파티션의 사용-구성정보 자료를 주기억장치에 생성해야 한다. 이러한 과정은 대용량 낸드 플래쉬 디바이스를 사용하는 경우 매우 긴 시간을 필요로 하게 되어 실제 환경에서는 낸드 플래쉬 디바이스를 채용하기가 어렵다. 본 논문에서는 차세대 비휘발성 저장장치의 바이트 단위의 접근 가능성을 활용한다. 낸드 플래쉬 디바이스 마운트시에 생성되는 최종 자료구조를 직접 NVRAM에 저장함으로써 낸드 플래실 디바이스의 메타 데이터를 스캔 하는 절차를 완전히 제거하였다. 즉, 낸드 플래처 디바이스의 마운트에 필요한 메타 데이터의 In-memory Data Structure를 NVRAM상에 저장하여 두면 이 후 NVRAM상에는 그 정보가 계속 유지되어 있기 때문에 낸드 플래쉬 디바이스의 마운트 동작은 단순히 Memory Pointer Mapping 정도의 간단하고 빠른 동작만으로도 충분하다. 본 논문에서는 비휘발성 메모리 소자가 블록 디바이스와 메모리 영역에 동시에 사상되어 있는 융합 파일 시스템을 성공적으로 개발하였다. 마운트 시간의 측정결과 효율적인 기존의 낸드 플래쉬 파일 시스템인 YAFFS에 비해 파티션의 크기나 파티션내 File의 개수에 관계없이 그 값이 매우 작고 고정적인 수치를 갖는다는 것을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.5
• /
• pp.793-801
• /
• 2022

Most Bluetooth devices are commonly used in various ways these days, but they can be often lost due to small-size devices. However, most Bluetooth protocol do not provide authentication functions to legitimate owners, and thus someone who obtains the lost Bluetooth device can easily connect to their smart devices to use it. In this paper, we propose NBAS can authenticates legitimate owners using NFT on lossy Bluetooth devices.NBAS generates a digital wallet on the blockchain using the decentralized network Ethereum blockchain and facilitating the MAC address of the Bluetooth device in the digital wallet. The owner of the wallet uses a private key to certify the Bluetooth device using NFT. The initial pairing time of NBAS was 10.25 sec, but the reconnection time was 0.007 sec similar to the conventional method, and the pairing rejection time for unapproved users was 1.58 sec on average. Therefore, the proposed NBAS effectively shows the device authentication over the conventional Bluetooth.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.1
• /
• pp.77-84
• /
• 2015

Most of the existing methods make the index key with every 6 words in every sentence in a document in order to identify copyright infringement between two documents. However, these methods has the disadvantage to take a long time to inspect the copyright infringement because of the long indexing time for the large-scale document. In this paper, we propose a method to select the longest word (called a feature bock) as an index key in the predetermined-sized window which scans a document character by character. This method can be characterized by removing duplicate blocks in the process of scanning a document, dramatically reducing the number of the index keys. The system with this method can find the copyright infringement positions of two documents very accurately and quickly since relatively small number of blocks are compared.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.10a
• /
• pp.867-869
• /
• 2012

FRUC(Frame Rate Up Conversion) is core techniques for higher quality terminals or low channel rate. For these applications, in this paper, we propose a block-based reliability evaluation method for FRUC techniques using bi-lateral symmetrical motion estimation. First, in order to measure the reliability, by introducing cost evaluation tools such as motion vector consistency as well as temporal matching and spatial matching characteristics and then by combining these tools, we propose an efficient method which arrange the blocks according to distortion size. Through several simulations, it is shown that the proposed method is very effective in finding the high distortion blocks. Furthermore, it is expected that the proposed method can be effectively utilized in FRUC techniques and Distributed Video Coding technologies.