• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.33-42
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• 2012

Rapid evolution of wired and wireless technologies results in various types of embedded systems, and the software to be embedded into those devices now needs the flexibility rather than the fixedness which was well-known property for the embedded software in the past. Mobile agent is one of the useful distributed technologies of reducing network load and latency because of its disconnected operations and high asynchrony. In this paper, a component-based mobile agent framework, called EmHUMAN, is designed and implemented for structural embedding into the devices showing different functions and resource constraints. It consists of 3 layers of components. Based on those components, a structural embedding, considering resource constraints of required functions, amount of storage space, computing power, network bandwidth, ${\ldots} $ etc can be performed. The components in each layer can be extended with addition of new components, removing some components and modifying components. EmHUMAN plays the role of a framework for developing mobile agent based distributed systems. It is also a mobile agent system by itself. EmHUMAN provides several utilities as built-in API's, and thus high effectiveness in programming mobile agents can be achieved.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.564-570
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• 2006

This paper presents a new real-time system design methodology for embedded system as well as event-driven real time application. It is required to implement a deadline handling mechanism in order to satisfy a large-scale distributed real time application. When we design real time system, it has handled a deadline and is important to measure / control a timing issue. These timing constraints usually associated with an interface between model and system. There are many case tools that supporting a real time application, for example, UML, graphic language for designing real time system, but they cannot provide efficient way to handle deadline miss. Therefore, users have to design deadline handler manually when they need to use it. This paper contributes solving the problems of user-level deadline handling for an embedded system. Also, it also discusses an efficient deadline handler design mechanism using on RoseRT, which is a graphical CASE tool supporting from UML.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.77-82
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• 2023

Multi-cloud rendering has been attracting attention recently as the computational load of rendering fluctuates over time and each rendering process can be performed independently. However, it is challenging in multi-cloud rendering to deliver large amounts of input data instantly with consistency constraints. In this paper, we develop a new distributed file system for multi-cloud rendering. In our file system, a local machine maintains a file server that manages versions of rendering input files, and each cloud node maintains a rendering cache manager, which performs distributed cooperative caching by considering file versions. Measurement studies with rendering workloads show that the proposed file system performs better than NFS and the uploading schemes by 745% and 56%, respectively, in terms of I/O throughput and execution time.

• Review of KIISC
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• v.27 no.2
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• pp.34-40
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• 2017

제어시스템(발전시설, 전력시설, 교통시설 등)은 생산성, 가용성, 안전성을 목적으로 다양한 제어기기들로 구성되며, 물리적으로 다양한 위치에 분산되어 운영되고 있다. 그리고 안전성과 가용성을 유지하기 위해 시스템 도입 시 기존 시스템에 영향을 미치지 않는지 검증을 수행 후 시스템을 도입한다. 이러한 이유로 신규 기술의 도입이나, 기기의 변경이 자유롭지 않다. 이와 같은 제어시스템의 특성으로 인해 현재 증가되고 있는 제어시스템 사이버공격에 대한 보안대책 또는 기술들의 적용이 쉽지 않아 사이버공격에 취약한 상황이다. 제어시스템은 상위 시스템의 제어 명령을 통해 하위 제어기기 또는 필드기기를 제어하는 형태로 제어 명령의 무결성 유지가 특히 중요하다. 이는 곧 제어시스템에 환경에 접근한 공격자가 인가되지 않은 장비를 제어시스템에 연결하고, 악성 제어명령을 전송하게 된다면 제어기기는 이를 인지하지 못하고 정지되거나 오작동을 유발 할 수 있다는 것을 의미한다. 본 논문에서는 제어시스템 내 제어명령의 무결성 유지를 위해 임베디드 Add-on 단말을 통해 OTP 값을 생성, 전달, 검증하는 방안을 제안한다. 해당 방안은 상위노드와 하위노드 사이에 Add-on 장치를 두어 상위노드에서 제어명령 발생 시, 제어명령에 OTP값을 통해 캡슐화하고 하위노드로 전달한다. Add-on 장비는 일반 IT시스템과 상이한 제어시스템의 특성에 맞게 고안되었으며 제어시스템 내에 발생되는 제어명령 위변조, 제어명령 재사용 공격 등을 차단 할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12B
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• pp.1022-1036
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• 2004

In mobile cellular network the ever-changing location of a mobile host necessitates the continuous tracking of its current position and efficient management of location information. A database called Home Location Register(HLR) plays a major role in location management in this distributed environment, providing table management, index management, and backup management facilities. The objectives of this paper are to identify the p개blems of the current HLR system through rigorous analysis, to suggest solutions to them, and to propose a new architecture for the HLR system. In the HLR system, a main memory database system is used to provide real-time accesses and updates of subscriber's information. Thus it is suggested that the improvement bemade to support better real-time facilities, to manage subscriber's information more reliably, and to accommodate more subscribers. In this paper, I propose an efficient backup method that takes into account the characteristics of HLR database transactions. The retrieval speed and the memory usage of the two-level index method are better than those of the T-tree index method. Insertion md deletion overhead of the chained bucket hashing method is less than that of modified linear hashing method. In the proposed backup method, I use two kinds of dirty flags in order to solve the performance degradation problem caused by frequent registration-location operations. Performance analysis has been performed to evaluate the proposed techniques based on a system with subscribers. The results show that, in comparison with the current techniques, the memory requirement is reduced by more than 62%,directory operations, and backup operation by more than 80%.

• The Journal of Korean Association of Computer Education
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• v.13 no.6
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• pp.99-104
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• 2010

USN Fire Prevention System is an intelligent system that detects the fire through the value which has got from a sensor such as temperature, humidity, intensity of illumination, acceleration, carbon dioxide(CO2) and so on. And then send it to the operator also use the algorithmic fire detection to operate fire extinguish system on. It is among U-Disaster Prevention System which has prevented fire lately. Configuration of the packet was designed to make the most of lightweight and fast processing for low power consumption. Recently listed in the encryption algorithm is applied each DES, 3DES, AES and HIGHT. So objective was to faster encryption than encryption of high-performance finally domestic standard encryption algorithm HIGHT were suitable for the fire prevention system needed frequent sensing time.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.263-266
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• 2005

실시간 시스템은 시간적 정확성을 갖기 때문에 소형 임베디드 시스템부터 대형 분산 시스템까지 많은 분야에서 사용되고 실시간 시스템을 기반으로 하는 실시간 프로그램도 많은 분야에서 사용되고 있다. 이러한 실시간 프로그램의 시간적 특성을 지키기 위해 개발자들은 프로그램 개발에 집중하지 못하고 실행시간의 정의와 정의한 실행시간의 정확성 검사에 많은 시간을 보내고 있다. 실시간 시스템에 대한 연구 결과로서 TMO 모델은 실시간 개념에 따른 시간 처리의 다양한 기능을 지원하고, 응답시간을 보장하여 개발자가 프로그램 개발에 집중할 수 있다. 하지만, 실행시간의 정의는 개발자에 의해 이루어지기 때문에 이를 정의하고 그 정확성 여부를 확인하는 작업은 어렵다. 이러한 문제로 인하여 실행시간 정의의 기준점을 제시할 수 있는 도구가 필요하지만 이를 위한 TMO 분석 도구에 대한 연구는 미흡하다. 이에 본 논문에서는 TMO 기반 정적 분석 도구를 위한 PS-Block을 제시한다. PS-Block은 블록 단위로 실행시간을 분석할 수 있는 기반으로써 프로그램을 작업 단위로 분리하여 분석할 수 있도록 한다. 이를 기반으로 실행시간을 분석하여 시간 정보 결정의 기준으로 하고, 실시간 메소드의 적시성 확인을 쉽게 함으로써 실시간/신뢰성의 향상과 개발 기간을 단축할 수 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4528-4535
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• 2014

In this paper, a distributed evacuation system based on the positioning information of subway passengers is proposed. Recently, the subway station is becoming complicated by combining with shopping malls, and movie theaters. Compared to the increasing complexity of subway stations, evacuation systems are less complex. Subway passengers in each cell were estimated to use the access point in the subway cells and statistics information. The evacuation route is provided through a direction indicator and push alarm of a smart phone based on estimated the number of passengers and exit information of the subway station. Based on this schemes, a quick and safe evacuation system of subway passengers was proposed. The number of connection passengers was estimated using AP with OpenWrt embedded OS installed. The average error rate of the number of passenger was confirmed to be 15%, 17% and 23% at the confidence parameter of $1{\sigma}$, $2{\sigma}$, and $3{\sigma}$, respectively, through a simulation. The possibility of the system through a simple experiment was examined.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.70-76
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• 2010

This paper Extended ELZW(EBCDIC Lempel Ziv Welch) algorithm uses 2 byte prefix field for pointer of a table and 1 byte suffix field for repeat counter. where, a prefix field uses a pointer(index) of compression table and a suffix field uses a counter of overlapping or recursion text data in compression table. To increase compression ratio, after construction of compression table, table data are properly packed as different bit string in accordance with a alphabet, Hangeul, and pointer respectively. Therefore, proposed ELZW algorithm is superior to 1byte LZW algorithm as 5.22 percent and superior to 2byte LZW algorithm as 8.96 percent.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.87-88
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• 2007

URC(Uniform Resource Identifier) 로봇은 기존의 로봇 자체에서 처리하던 기능을 네트워크를 통하여 외부로 분산시켜 외부의 센싱기능과 프로세싱 기능을 활용하여 효율적으로 구동하기 위한 것이다. 즉 많은 파워가 요구되는 센싱 기능이나 프로세싱 기능을 외부에 있는 서버를 활용하여 서비스를 제공함으로써 간단한 로봇으로도 고도의 서비를 제공이 가능토록하여 가격 경쟁력을 갖도록 하기 위함이다. 본 논문에서는 URC 로봇을 원격에서 모니터링 및 제어가 가능하도록 웹 서비스 기술을 임베디드 시스템 환경에 맞게 최적화하였다. 서비스는 인터넷 기반의 SOAP 프로토콜을 통하여 교환되는 XML 기반 메시지를 통하여 다른 응용 에이전트들과 직접적인 상호작용을 지원함으로서 이기종간 호환 및 표준 플랫폼을 지원할 수 있다. 본 논문에서는 URC 시범서비스 참가 로봇인 네토로(한울로보틱스)에 본 연구결과를 적용하여 기능 및 안정성을 검증하였다.