• 대한산업공학회지
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• 제28권2호
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• pp.139-146
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• 2002

The third generation mobile communication needs to provide multimedia service with increased data rates. Thus an efficient allocation of radio and network resources is very important. This paper models the 'burst switching' as an efficient radio resource allocation scheme and the performance is compared to the circuit and packet switching. In burst switching, radio resource is allocated to a call for the duration of data bursts rather than an entire session or a single packet as in the case of circuit and packet switching. After a stream of data burst, if a packet does not arrive during timer2 value ($\tau_{2}$), the channel of physical layer is released and the call stays in suspended state. Again if a packet does not arrive for timerl value ($\tau_{1}$) in the suspended state, the upper layer is also released. Thus the two timer values to minimize the sum of access delay and queuing delay need to be determined. In this paper, we focus on the decision of $\tau_{2}$ which minimizes the access and queueing delay with the assumption that traffic arrivals follow Poison process. The simulation, however, is performed with Pareto distribution which well describes the bursty traffic. The computational results show that the delay and the packet loss probability by the burst switching is dramatically reduced compared to the packet switching.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제23권10호
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• pp.594-598
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• 2017

정수 형태의 배열로 이루어진 데이터가 주식 시장과 같은 원본으로부터 셀 수 없을 정도로 매일 생성되고 있다. 정수 배열을 저장하는 데에 감마 코드, 델타 코드, 피보나치 코드 등을 포함한 범용 코드가 일반적으로 사용된다. 이 배열을 적은 공간을 차지하게 하면서 빠른 시간에 특정 원소에 접근하는 연산을 수행할 수 있게 하려는 시도가 진행되었다. 본 논문에서는 간결한 자료구조의 특성을 활용하여 부호화된 정수 배열에서의 임의 접근을 가능하도록 한 코드 시스템을 제시한다. 이는 코드 시스템에 사용되는 구획 문자 비트열을 압축하면서 질의 수행 시간을 상수 시간에 지원하는 자료구조를 통해 구현되었다. 실험 결과를 통해 범용 코드 시스템보다 더 적은 공간과 시간을 사용해 정수 배열을 표현할 수 있다는 것을 보인다.

• 대한임베디드공학회논문지
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• 제10권3호
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• pp.139-150
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• 2015

The major components of IoT(Internet of Things) environment are IoT devices rather than the conventional desktop computers. One of the intrinsic characteristics of IoT devices is diversity in view of data type and data access method. In addition, IoT devices usually deal with real-time data. In order to use such IoT data for internal business or cloud services, an IoT platform capable of easy domain management and consistent data access interface is required. This paper proposes a Linux FUSE-based virtual file system connecting IoT devices on POSIX file system view. It is possible to manage IoT domain with the native Linux utilities such as mkdir, mknod, ls and find in the file system. Also, the file system makes it possible to access or control IoT devices through POSIX interface such as open(), read(), write() or close() without any separate APIs or utilities. A test result shows that the management performance of the file system is lower than that of linux file system negligibly.

• 디지털산업정보학회논문지
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• 제9권2호
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• pp.63-71
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• 2013

WAVE(Wireless Access for Vehicular Environment) System is a communication technology to monitor system failure and vehicle functions and management services to prevent possible incidents of driving a vehicle. In this paper, we have designed and implemented the mutual message processing through parameter between WME management module that manages WAVE system and MLME that manages the upper layer MAC(Media Access Control) module. Also, in order to verify the validity, we have carried out experiments to compare the speed of data processing by dividing data of 1Mbyte, 2Mbyte, 3Mbyte into the packets of 2KByte and 4KByte. Experiments data processing speed of 2KByte packet were shown about 173.62ms in 1MByte, 2MByte about 352.61ms, 3MByte about 550.13ms and, data processing speed of 4KByte packet, 1MByte approximately 87.56ms, 2MByte about 177.94ms, 3MByte about 277.18ms. Therefore, in WAVE system, the mutual messages processing through the parameters between WME and MLME module can be utilized in the various service of ITS(Intelligent Transportation Systems) depending on the speed of data processing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2302-2322
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• 2012

Wireless Body Area Networks (WBANs) are introduced as an enabling technology in tele-health for patient monitoring. Designing an efficient Medium Access Control (MAC) protocol is the main challenge in WBANs because of their various applications and strict requirements such as low level of energy consumption, low transmission delay, the wide range of data rates and prioritizing emergency data. In this paper, we propose a new MAC protocol to provide different requirements of WBANs targeted for medical applications. The proposed MAC provides an efficient emergency response mechanism by considering the correlation between medical signals. It also reduces the power consumption of nodes by minimizing contention access, reducing the probability of the collision and using an efficient synchronization algorithm. In addition, the proposed MAC protocol increases the data rate of the nodes by allocating the resources according to the condition of the network. Analytical and simulation results show that the proposed MAC protocol outperforms IEEE 802.15.4 MAC protocol in terms of power consumption level as well as the average response delay. Also, the comparison results of the proposed MAC with IEEE 802.15.6 MAC protocol show a tradeoff between average response delay and medical data rate.

• International journal of advanced smart convergence
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• 제9권4호
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• pp.34-41
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• 2020

Nowadays, the advanced smart convergences of the artificial intelligence (AI) and the internet of things (IoT) have been more and more important, in the fifth generation (5G) and beyond 5G (B5G) mobile communication. In 5G and B5G mobile networks, non-orthogonal multiple access (NOMA) has been extensively investigated as one of the most promising multiple access (MA) technologies. In this paper, we investigate the achievable data rate for the asymmetric binary pulse amplitude modulation (2PAM), in non-orthogonal multiple access (NOMA). First, we derive the closed-form expression for the achievable data rate of the asymmetric 2PAM NOMA. Then it is shown that the achievable data rate of the asymmetric 2PAM NOMA reduces for the stronger channel user over the entire range of power allocation, whereas the achievable data rate of the asymmetric 2PAM NOMA increases for the weaker channel user improves over the power allocation range less than 50%. We also show that the sum rate of the asymmetric 2PAM NOMA is larger than that of the conventional standard 2PAM NOMA, over the power allocation range larger than 25%. In result, the asymmetric 2PAM could be a promising modulation scheme for NOMA of 5G systems, with the proper power allocation.

• International Journal of Computer Science & Network Security
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• 제24권7호
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• pp.123-127
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• 2024

Cloud computing services has gained increasing popularity in recent years for supporting various on demand and scalable services for IT consumers where there is a need of less investment towards infrastructure. While storage architecture of cloud enjoys a more robust and fault-tolerant cloud computing network, such architecture also poses a number of security challenges especially when applied in applications related to social networks, Financial transactions, etc. First, as data are stored and maintained by individual virtual machines so Cloud resources are prone to hijacked. Such attacks allow attackers to create, modify and delete machine images, and change administrative passwords and settings successfully. hence, it is significantly harder to ensure data security. Second, Due to dynamic and shared nature of the Cloud, data may be compromised in many ways. Last but not least, Service hijacking may lead to redirect client to an illegitimate website. User accounts and service instances could in turn make a new base for attackers. To address the above challenges, we propose in this paper a distributed data access control scheme that is able to fulfil fine-grained access control over cloud data and is resilient against strong attacks such as compromise and user colluding. The proposed framework exploits a novel cryptographic primitive called attribute-based encryption (ABE), tailors, and adapts it for cloud computing with respect to security requirements

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2011년도 춘계학술발표대회
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• pp.871-874
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• 2011

The fast emerging of network technology and the high demand of computing resources have prompted many organizations to outsource their storage and computing needs. Cloud based storage services such as Microsoft's Azure and Amazon's S3 allow customers to store and retrieve any amount of data, at anytime from anywhere via internet. The scalable and dynamic of the cloud storage services help their customer to reduce IT administration and maintenance costs. No doubt, cloud based storage services brought a lot of benefits to its customer by significantly reducing cost through optimization increased operating and economic efficiencies. However without appropriate security and privacy solution in place, it could become major issues to the organization. As data get produced, transferred and stored at off premise and multi tenant cloud based storage, it becomes vulnerable to unauthorized disclosure and unauthorized modification. An attacker able to change or modify data while data inflight or when data is stored on disk, so it is very important to secure data during its entire life-cycle. The traditional cryptography primitives for the purpose of data security protection cannot be directly adopted due to user's lose control of data under off premises cloud server. Secondly cloud based storage is not just a third party data warehouse, the data stored in cloud are frequently update by the users and lastly cloud computing is running in a simultaneous, cooperated and distributed manner. In our proposed mechanism we protect the integrity, authentication and confidentiality of cloud based data with the encrypt- then-upload concept. We modified and applied proxy re-encryption protocol in our proposed scheme. The whole process does not reveal the clear data to any third party including the cloud provider at any stage, this helps to make sure only the authorized user who own corresponding token able to access the data as well as preventing data from being shared without any permission from data owner. Besides, preventing the cloud storage providers from unauthorized access and making illegal authorization to access the data, our scheme also protect the data integrity by using hash function.

• 디지털융복합연구
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• 제12권6호
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• pp.311-316
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• 2014

소셜 네트워크와 스마트폰의 대중화로 인하여 서버에 저장되어 있는 데이터를 손쉽게 사용할 수 있는 빅데이터 서비스가 증가하고 있다. 빅 데이터 처리기술은 빅 데이터 서비스에서 가장 중요한 기술 중 하나지만 보안에 대한 해결책이 미미한 상태이다. 본 논문에서는 빅 데이터 서비스에서 제공되는 분산된 대용량 데이터를 이중 해쉬를 이용하여 사용자가 손쉽게 데이터에 접근할 수 있는 다중 해쉬 체인 기반의 데이터 분산 처리 기법을 제안한다. 제안 기법은 빅 데이터를 데이터의 종류, 기능, 특성에 따라 해쉬 체인으로 묶어 데이터에 높은 처리량을 지원한다. 또한, 토큰 및 데이터 노드가 공격자에게 노출되었을 때 발생하는 보안 취약점을 해결하기 위해서 데이터의 속성 정보를 해쉬 체인의 연결 정보로 활용하여 빅 데이터의 접근 제어를 분산 처리한다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2014년도 추계학술발표대회
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• pp.137-139
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• 2014

Objective: Data exchange, interoperability, and access as a service in healthcare information management systems (HIMS) is the basic need to provision health-services. Data existing in various HIMS not only differ in the basic underlying structure but also in data processing systems. Data interoperability can only be achieved when following a common structure or standard which is shareable such as semantics based structures. We propose web-enabler: A Hadoop MapReduce based distributed approach to transform the existing huge variety data in variety formats to a conformed and flexible ontological format that enables easy access to data, sharing, and providing various healthcare services. Results: For proof of concept, we present a case study of general patient record in conventional system to be enabled for analysis on the web by transforming to semantics based structure. Conclusion: This work achieves transformation of stale as well as future data to be web-enabled and easily available for analytics in healthcare systems.