• Journal of information and communication convergence engineering
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• v.16 no.1
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• pp.23-30
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• 2018

In cognitive radio (CR), spectrum sensing is an essential function since secondary users (SUs) must determine whether the primary user (PU) is utilizing the channel or not, and furthermore, SUs opportunistically access the licensed channel when the PU is absent. In this paper, spectrum sensing is implemented by energy detection, and a software-defined radio testbed is built to evaluate sensing performance by energy detection in a real environment. In particular, the testbed was built based on the GNU's Not Unix (GNU) Radio software platform and Universal Software Radio Peripheral National Instruments 2900 devices. More specifically, a new block of energy detection is developed by using an out-of-tree module from GNU Radio. To successfully integrate CR into the cloud computing paradigm, we also implement cloud computing-based spectrum sensing by utilizing a cloud server with ThingSpeak, such that we can store, process, and share the sensing information more efficiently in a centralized way in the cloud server.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.383-386
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• 2006

In this study, we propose a new fast algorithm for calculating short range forces in molecular dynamics, This algorithm uses a new hierarchical tree data structure which has a high adaptiveness to the particle distribution. It can divide a parent cell into k daughter cells and the tree structure is independent of the coordinate system and particle distribution. We investigated the characteristics and the performance of the tree structure according to k. For parallel computation, we used orthogonal recursive bisection method for domain decomposition to distribute particles to each processor, and the numerical experiments were performed on a 32-node Linux cluster. We compared the performance of the oct-tree and developed new algorithm according to the particle distributions, problem sizes and the number of processors. The comparison was performed sing tree-independent method and the results are independent of computing platform, parallelization, or programming language. It was found that the new algorithm can reduce computing cost for a large problem which has a short search range compared to the computational domain. But there are only small differences in wall-clock time because the proposed algorithm requires much time to construct tree structure than the oct-tree and he performance gain is small compared to the time for single time step calculation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.6
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• pp.2591-2611
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• 2020

Botnets have become one of the most significant threats to Internet-connected smartphones. A botnet is a combination of infected devices communicating through a command server under the control of botmaster for malicious purposes. Nowadays, the number and variety of botnets attacks have increased drastically, especially on the Android platform. Severe network disruptions through massive coordinated attacks result in large financial and ethical losses. The increase in the number of botnet attacks brings the challenges for detection of harmful software. This study proposes a smart framework for mobile botnet detection using static analysis. This technique combines permissions, activities, broadcast receivers, background services, API and uses the machine-learning algorithm to detect mobile botnets applications. The prototype was implemented and used to validate the performance, accuracy, and scalability of the proposed framework by evaluating 3000 android applications. The obtained results show the proposed framework obtained 98.20% accuracy with a low 0.1140 false-positive rate.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.151-156
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• 2011

The Korean domestic cloud market will reach a value of 2 trillion Korean won by 2014. The domestic market is expected to grow rapidly in size despite the fact that there exist activation barriers in mobile cloud services, concerns about the reliability of service, and concerns about security and confidentiality of data. Under these circumstances, existing IT security technologies may be be utilized to provide sufficient response characteristics. Despite this, they must be optimized for mobile cloud computing and enhanced to mitigate inherent security flaws. In this study, mobile cloud security is covered along with use cases that cover the cases where mobile devices are particularly vulnerable and suggest ways to mitigate security vulnerabilities.

• Journal of Information Technology and Architecture
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• v.10 no.2
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• pp.197-209
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• 2013

This study analyzes the nature of consumers and smart phones as well as its limitations that domestic mobile communication companies confront. According to the analysis results, emerging technologies such as 5G communication, pervasive computing, augmented reality, and big data seem to have significant effect on the ICT ecosystem in the near future. Based on the results, this study suggests four counterstrategies for domestic mobile communication companies: big data strategy, preparation of things acting as a main communication agent, new service platform development, and 'total life care service provider' strategy.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.858-863
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• 2010

In order to enhance encoding speed in dynamic image encoding using H.264/AVC, reducing the time for motion estimation which takes a large portion of the processing time is very important. An approach using graphics processing unit(GPU) as a coprocessor to assist the central processing unit(CPU) in computing massive data, will be a way to reduce the processing time. In this paper, we present an efficient block-level parallel algorithm for the motion estimation(ME) on a computer unified device architecture(CUDA) platform developed in general-purpose computation on GPU. Experiments are carried out to verify the effectiveness of the proposed algorithm.

• Journal of Computing Science and Engineering
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• v.2 no.4
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• pp.357-374
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• 2008

Over the past few decades, a considerable number of studies have been conducted on the technologies to build an UAV (Unmanned Aerial Vehicle) control system. Today, focus in research has moved from a standalone control system towards a network-centric control system for multiple UAV systems. Enabling the design of such complex systems in easily understandable forms that are amenable to rigorous analysis is a highly desirable goal. In this paper, we discuss our experimental evaluation of the Time-triggered Message-triggered Object (TMO) structuring scheme in the design of the UAV control system. The TMO scheme enables high-level structuring together with design-time guaranteeing of accurate timings of various critical control actions with significantly smaller efforts than those required when using lower-level structuring schemes based on direct programming of threads, UDP invocations, etc. Our system was validated by use of environment simulator developed based on an open source flight simulator named FlightGear. The TMO-structured UAV control software running on a small computing platform was easily connected to a simulator of the surroundings of the control system, i.e., the rest of the UAV and the flight environment. Positive experiences in both the TMO-structured design and the validation are discussed along with potentials for future expansion in this paper.

• Journal of The Korean Association of Information Education
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• v.6 no.3
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• pp.338-346
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• 2002

In these days, because of internet activation, each organs of education or istructors develop and manage the web based education system, but component development that used in web based education system development is not ready. When we develop the web education system using component, we can gain the various desired result of reusability, interaction in various computers, expansion, reduction of development time, saving of development expense, etc. Therefore, in this paper we classified the web based education components by the function of web based education system, did modeling for development process of components, and chose the component platform that can reuse components in distributed computing environment that the client/server environment is supported. The induction of these web based education components will be give many assistance to development of the web based education system.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.93-96
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• 2005

PC 그리드 컴퓨팅(Grid Computing) 환경이란 기존의 클라이언트/서버 구조를 최대한 이용하여 텍스트 정보뿐만 아니라 컴퓨팅 파워, 데이터 저장 장치, 첨단 실험 장비 등 가용한 모든 자원들, 나아가 인력 자원들까지도 인터넷을 통해 공유하는 기술이다. 각 클라이언트는 공동으로 작업하는 프로젝트의 처리 결과를 중심이 되는 서버에 전송한다. 중심 서버에서는 각 클라이언트들의 개별적인 처리 결과를 종합하여 단일 결과를 도출한다. PC 그리드 컴퓨팅 환경하에서 분산된 모든 서비스나 장치들이 상호작용 하기 위해서는 해당 서비스가 제공하는 것이 무엇인지, 또한 자신이 원하는 자원이 어디에 위치해 있는지를 정확히 알아야만 한다. 이런 일련의 작업들을 서비스 디스커버리(Service Discovery)라 한다. 이기종 에이전트 플랫폼 간에 자원의 공유를 위해서 FIPA 에서는 서비스 디스커버리에 대한 명세서를 제안하고 있다. 본 논문에서는 PC 그리드 컴퓨팅 환경에서 이기종 에이전트 플랫폼간에 서비스 디스커버리가 이루어 질 수 있도록 연구 및 개발을 목적으로 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.1-17
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• 2017

Mobile Cloud Computing has become a promising computing platform. It moves users' data to the centralized large data centers for users' mobile devices to conveniently access. Since the data storage service may not be fully trusted, many public verification algorithms are proposed to check the data integrity. However, these algorithms hardly consider the huge computational burden for the verifiers with resource-constrained mobile devices to execute the verification tasks. We propose an energy-efficient algorithm for assigning verification tasks (EEAVT) to optimize the energy consumption and assign the verification tasks by elastic and customizable ways. The algorithm prioritizes verification tasks according to the expected finish time of the verification, and assigns the number of checked blocks referring to devices' residual energy and available operation time. Theoretical analysis and experiment evaluation show that our algorithm not only shortens the verification finish time, but also decreases energy consumption, thus improving the efficiency and reliability of the verification.