• Asia pacific journal of information systems
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• v.30 no.1
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• pp.21-30
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• 2020

Bitcoin (BTC) is a type of cryptocurrency that supports transaction/payment of virtual money between BTC users without the presence of a central authority or any third party like bank. It uses some cryptographic techniques namely public- and private-keys, digital signature and cryptographic-hash functions, and they are used for making secure transactions and maintaining distributed public ledger called blockchain. In BTC system, each transaction signed by sender is broadcasted over the P2P (Peer-to-Peer) Bitcoin network and a set of such transactions collected over a period is hashed together with the previous block/other values to form a block known as candidate block, where the first block known as genesis-block was created independently. Before a candidate block to be the part of existing blockchain (chaining of blocks), a computation-intensive hard problem needs to be solved. A number of miners try to solve it and a winner earns some BTCs as inspiration. The miners have high computing and hardware resources, and they play key roles in BTC for blockchain formation. This paper mainly analyses the underlying cryptographic techniques, identifies some weaknesses and proposes their enhancements. For these, two modifications of BTC are suggested ― (i) All BTC users must use digital certificates for their authentication and (ii) Winning miner must give signature on the compressed data of a block for authentication of public blocks/blockchain.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.77-83
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• 2010

Vehicular Ad Hoc Networks are self-organizing Peer-to-Peer networks that typically have highly mobile vehicle nodes, moving at high speeds, very short-lasting and unstable communication links. VANETs are formed without fixed infrastructure, central administration, and dedicated routing equipment, and network nodes are mobile, joining and leaving the network over time. So, VANET-security is very vulnerable for the intrusion of malicious and misbehaving nodes in the network, since VANETs are mostly open networks, allowing everyone connect, without centralized control. In this paper, we propose a rough set based anomaly detection method that efficiently identify malicious behavior of vehicle node activities in these VANETs, and the performance of a proposed scheme is evaluated by a simulation in terms of anomaly detection rate and false alarm rate for the threshold ${\epsilon}$.

• Annual Conference of KIPS
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• 2002.04a
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• pp.183-186
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• 2002

MPEG-4는 기존의 MPEG-1, MPEG-2와 달리 멀티미디어를 위한 객체 기반의 부호화에 관한 표준이다. MPEG-4의 장면은 여러 개의 객체로 이루어져 있기 때문에 각 객체들을 시간, 공간적으로 표현하기 위한 장면 기술의 방법으로 BIFS(Binary Format for Scene description)를 규정하고 있다. MPEG-4 단말기에서는 부호화된 BIFS 정보를 복호화하여 각 객체들을 화면에 구성하게 되며, 객체의 특성, 행동들을 정의하거나 변경할 수 있고 새로운 객체들을 포함하는 등의 사용자 상호 작용에 따른 기능을 수행하게 된다. 그러나, 사용자 상호 작용에 따른 장면 재구성은 초기 장면을 구성할 때 기술된 장면 정보를 벗어날 수 없는 제약을 받게 된다. 따라서 본 논문에서는 BIFS 수정 정보 발생기 (BIFS modifier)를 가진 시스템 구조를 제안한다. 제안된 시스템 구조에서 BIFS 수정 발생기는 사용자의 상호 작용이 발생한 노드를 전달 받아 이에 상응하는 BIFS 정보를 기존의 BIFS 정보에서 찾은 후 이를 수정하여 BIFS 변경(BIFS update) 명령을 만들어내고 이에 따라 장면을 재구성하여 동적인 장면 구성을 가능하게 한다. 또한, 제안된 시스템 구조를 주요 응용 분야인 peer-to-peer(P2P)를 가정한 네트웍 기반의 게임에 직접 적용하여 보았다.

• Korean Journal of Biological Psychiatry
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• v.2 no.1
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• pp.115-122
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• 1995

This study was performed to know the relationship between neurologic soft signs (NSS) and clinical variables such as psychopathology. history of illness, and premorbid social adjustment in patients with schizophrenia. The authors evaluated NSS in 31 patients with schizophrenia using the structured tool for measuring neurologic abnormalities, Neurological Evaluation Scale- Korean Version(NES-K). Relationships between NSS and clinical variables such as duration of illness, intensity of precipitating stressors, duration of outpatient treatment, schooling, peer relationship, total duration of unemployment, total days of psychiatric admission, age, total days of being medicated, age at the first psychiatric admission, frequency of admissions, content of treatment, social adjustment, and severity of symptoms were analyzed. Differences between paranoid and non-paranoid schizophrenics were examined. In addition, Differences between patients with schizophrenia who have predominant positive symptoms and who have predominant negative symptoms were examined too. Total scores of NES-K were correlated with lower schooling (${\gamma}$=0.44, p<0.01). Scores of motor coordination subcategory were correlated with poor peer relationship(${\gamma}$=0.67, p<0.001). Other clinical variables were not correlated with any scores of NES-K. Paranoid and non-paranoid schizophrenics were not different in scores of NES-K. Also positive and negative schizophrenics were not different in scores of NES-K. Most clinical variables except schooling and peer relationship were not related with NSS. This results indicated that the meaning of these signs was not fully be understood. Introduction of the new classification concepts such as deficit or non-deficit syndrome will be helpful to elucidate the meaning of NSS in patients with schizophrenia.

• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1369-1378
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• 2017

Pub/Sub (Publish/Subscribe) paradigm is a simple and easy to use model for interconnecting applications in a distributed environment. In general, subscribers register their interests in a topic or a pattern of events and then asynchronously receive events matching their interest, regardless of the events' publisher. In order to build a low latency lightweight pub/sub system for Internet of Things (IoT) services, we propose a GQSFPS (Group Quorum System-based Fog Pub/Sub) system that is a core component in the event-driven service oriented architecture framework for IoT services. The GQSFPS organizes multiple installed pub/sub brokers in the fog servers into a group quorum based P2P (peer-to-peer) topology for the efficient searching and the low latency accessing of events. Therefore, the events of IoT are cached on the basis of group quorum, and the delay-sensitive IoT applications of edge devices can effectively access the cached events from group quorum fog servers in low latency. The performance of the proposed GQSFPS is evaluated through an analytical model, and is compared to the GQPS (grid quorum-based pud/sub system).

• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.209-215
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• 2005

The first wave of e-government projects dating from the early 1990s primarily focused on setting up national and global information infrastructure, internal organizational reform, digital procurement, and the digital delivery of government services to citizens. Most of these e-Government projects have concentrated on the development of systems focusing on strengthening the formal agencies and institutions of government. To date, despite many theoretical and empirical studies on citizen involvement in terms of governance, relatively little attention has been paid to developing e-government systems with a focus on improving citizen involvement, which we call e-governance systems. This paper discusses the characteristics of the e-governance systems, identifies core requirements for its development, and suggests an e-governance system architecture that can satisfy the core requirements.

• Journal of the Korea Society of Computer and Information
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• v.11 no.5 s.43
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• pp.105-114
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• 2006

Context-Awareness is a important technology to support optimized services automatically by recognizing various context informations in ubiquitous environments. Previous middlewares which supports ubiquitous environments used a centralized storage and DBMS to store and manage context informations and service contents. Centralized management of context informations and service contents sometimes hinders the autonomy of moving node and interoperability between difference middlewares. In this paper, we design the systems which stores context informations in moving node by distributed form and shares service contents between middlewares in distributed ubiquitous environments. And it provides Context-Aware scripts to supports the definition of context informations reasoning and execution of services. It verifies the usefulness of the designed systems by applying the scenario of music playing service based on context awareness

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1279-1284
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• 2009

With the advance of multimedia technology, multimedia sharing among multiple devices has become the main issue. This allows users to expect the peer-to-peer distribution of unprotected and protected contents over public network. Inevitably, this situation has caused an incredible piracy activity and Web sites have begun to provide copyrighted A/V data for free. In order to, protect the contents from illegal attacks and distribution, digital right management (DRM) is required. In this paper, we present the minimal cost scrambling scheme for securing the copyrighted multimedia using the data encryption standard (DES) encryption technique. Experimental results indicate that the proposed scrambling techniques achieve a very good compromise between several desirable properties such as speed, security, and file size.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.21-31
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• 2007

This Paper presents an SOA framework that enables smooth provision of service to ordinary users while also replacing the current B2B environment-oriented SOA framework. To that end, the proposed SOA will be reviewed for its concept, characteristics, and components. Key to its design is that it will be implemented using the prospective next-generation P2P platform known as JXTA. The proposed framework includes all the basic functions of other SOA frameworks, and will make Provision and use of services more easy compared with other frameworks. Under this service, data and applications controlling these data are provided in an enabling format, thereby addressing security problems. Another advantage of this proposed framework is that each peer is able to play all roles of a service provider, service client, and service registry.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.341-354
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• 2005

The main bottleneck for large scale VOD systems is bandwidth of storage or network I/O due to the large number of client requests simultaneously, and then efficient techniques are required to solve the bottleneck problem of the VOD system. Patching is one of the most efficient techniques to overcome the bottleneck of the VOD system through the use of multicast scheme. In this paper, we propose a new patching scheme, called P2P proxy patching, for improving the typical patching technique by jointly using the prefix caching and P2P proxy. In our proposed scheme, each client plays a role in a proxy to multicast a regular stream to other clients that request the same video stream. Due to the use of the P2P proxy and the prefix caching, the client requests that ive out of the patching window range can receive the regular stream from other clients in the previous patching group without allocating the new regular channels from the VOD server to the clients. In the performance study, we show that our patching scheme can reduce the server bandwidth requirement about $33\%$ less than that of the existing patching technique with respect to prefix size and request interval.