• Journal of the Korea Society for Simulation
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• v.19 no.1
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• pp.153-160
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• 2010

Most part of errors in software development process are included during the stage of requirements definition and design. And correction or elimination of errors from those stages requires much more efforts and costs than those from the later part of software development process. However, despite of the importance of the validation of requirement definition and design stages, several kinds of problem have made it hard to be done successfully. Therefore, in this paper, we introduce a novel validation process for the preliminary design stage. The validation process is based on simulations of model and it can be used to validate requirements and model simultaneously. Models in the validation process will take only the behavior of software and be built on Ptolemy framework. The usability of our validation process is confirmed with a case study over DNS system environment. And the result of simulation shows well-known errors or vulnerabilities can be found with simulations of model which has the behavior of software. This means our validation process can be used as a process to validate requirements and models during the early stage of software development process.

• Journal of KIISE:Information Networking
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• v.32 no.2
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• pp.167-179
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• 2005

In hierarchical Mobile IPv4 Networks the highest FA(Foreign Agent) may experience serious congestion and delay since the highest FA plays a role of CoA(Care of Address) for all mobile nodes in the domain, In this paper, we propose mechanism called 'HRFA(Hierarchical Root Foreign Agent)', which distributes the load imposed on the highest FA. In the proposed HRFA scheme, multiple HRFAs are selected to provide the similar service that is provided by the highest FA. According to which entity determines HRFAs, HRFA scheme is categorized into 'Active' and 'Passive' approaches. HRFA scheme is further categorized into 'All MN(Mobile Node)s' and 'New MNs' approaches, depending on which mobile nodes are assigned to a newly elected HRFA. Through a course of simulations, we investigate the performance of 4 possible combinations of HRFA schemes. We also compare the performance of the proposed HRFA schemes with the LMSP(Local Multicast Service Provider) scheme, which is a scheme to distribute the load of FA for multicast service in hierarchical wireless network domain. The simulation results show that the Passive & New MN approach performs best with respect to both the overhead and the load balancing.

• Journal of Cadastre & Land InformatiX
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• v.48 no.1
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• pp.55-70
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• 2018

The field of cadastre and land administration is susceptible to changes in technological development and requires a robust system to respond. In Mongolia, there is a need for a future-oriented and robust cadastral system to cope with these changes. Therefore, this study chose the Land Administration Domain Model (LADM) which is created by the International Organization for Standardization(ISO), and analyzed for its application to the cadastral system of Mongolia. For the application of LADM for Mongolia, we analyzed four packages and each class of LADM based on characteristics of Mongolia's cadastral system and cases of countries applying LADM. As a result of this analysis, we have completed LADM national profiling in Mongolia and proposed the possibility of applying LADM. In the future, based on this research, application of LADM will play an important role in Mongolian cadastral system where the current data model standardization is not established and is useful as a reference model.

• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.81-88
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• 2005

In this paper, the plug-in scheme for ENUM client and ENUM services was proposed using an ENUM DNS applied by E.164 telephone numbering. Especially, ENUM services(ENUM HTTP, ENUM FTP) were implemented according to ENUM root domain(e164.arpa).

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.520-523
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• 2011

가상화는 하나의 컴퓨팅 노드에 여러 개의 가상 머신을 구성하여 서버의 자원 활용률을 높여주는 매우 유용한 기술이다. 하지만 아직까지 멀티코어 기반의 전가상화(Full Virtualization) 환경에서 네트워크 I/O 성능 향상을 위한 연구는 미비하다. 또한 기존의 프로세스 스케줄링 기법은 통신을 수행하는 게스트 도메인의 프로세스들을 효과적으로 지원해주지 않는다. 이러한 문제를 해결하기 위하여 네트워크 I/O 가상화를 위한 통신 프로세스의 동적 스케줄링 방식을 제안한다. 기존의 프로세스 친화도 결정 기법을 기반으로 네트워크 I/O 가상화에 특화된 제안 기법은 전가상화 VMM(Virtual Machine Monitor)인 VirtualBox를 대상으로 구현되었으며, 성능 측정을 통하여 네 개의 가상 머신을 적용하였을 경우 기존 리눅스 스케줄러 대비 총 네트워크 사용량을 약 97% 상승 시킴을 보인다.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.8
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• pp.752-757
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• 2000

The recursive formulae, which can self-reproduce the state transition graphs, of one-dimensional cellular automata rule 15 with two states (0 and 1) and four different boundary conditions were founded by categorical access. The categorical access makes the evolution process for cellular automata be expressed easily since it enables the mapping of automata between different domains.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.23-26
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• 2008

본 논문에서는 로봇의 지능적 행위를 구현하기 위하여 인공지능의 몇 가지 기법을 휴머노이드 로봇에 적용하고 이를 테스트 도메인에서 실험하는 연구결과를 기술하였다. 본 연구에서 적용한 기법들은, 인공지능의 계획기법에 기반한 로봇의 계획생성, A^* 알고리즘을 적용한 길 찾기, 외부 센서 값에 기반한 장애물회피 및 로봇의 자기 위치인식, 그리고 원하는 물체를 파악하기 위해 템플릿 매칭을 이용한 영상인식 등 네 가지 방향으로 접근하였다. 전반적으로 로봇의 실험은, 웹 페이지로부터 사용자의 쇼핑 목록을 입력 받아, 인공지능의 계획기법에 기반하여 서버에서 이에 대한 실행계획을 만들고 난 후, 로봇이 서버로부터 TCP/IP 기반의 소켓 통신을 통하여 세부 실행계획을 전달받아 임무를 수행하게 된다. 또한 이러한 임무를 수행하기 위해서는 로봇자신의 현재위치에 대한 정보 및 목표물에 대한 위치인식이 요구되며, 이를 위해서 사전에 주어진 맵의 좌표를 찾아가는 방법을 사용하였다.

• Journal of Intelligence and Information Systems
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• v.7 no.2
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• pp.1-17
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• 2001

This paper deals with an agent-based decision-supporting system for Taguchi experiment planning. Among the four major parts of Taguchi experiment, the planning phase includes the most important decision-making issues such as determination of experiment objectives, quality characteristics, and control factors. The planning phase, however, has not been paid proper attention by experiment designers. In this research, an agent-based decision-supporting system for Taguchi experiment planning has been developed to facilitate the planning tasks of experiment designer. The decision-supporting system is composed of two agent-based mechanisms. The first employs an Internet agent that collects the domain knowledge from knowledge providers who may be distributed in remote places. Another agent then visualizes the collected knowledge and reports it to the experiment designer. Engineers who would normally have difficulties in collaborating because of limitations on their time or because they are in different places can easily work together in the same experiment team and brainstorm to make good decisions. The second agent-based mechanism offers context-sensitive advice generated by another intelligent agent during the experiment planning process. it prevents the experiment designer from making improper decisions, which will increase the feasibility of the experiment and minimize the unnecessary expense of time and resources.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.2
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• pp.239-249
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• 2003

A lot many WWW sites are come into the world more and more as Web is considered as the unified Internet information tool. The location of each site or resource is usually specified by a physical URL, which is often too long to remember and tends to raise difficulty to show the aim of the site intuitively by seeing it. Since any person or organization can get his/her own domain name easily, it is more desirable to use a logical URL with the domain name which can be chosen more compact to remember and meaningful to represent the ultimate intention of the site. This paper presents an implementation of a URL forwarding server which forwards a URL to another, so that a WWW site can use a logical URL instead of a physical one. The server consists of a domain mapper which uses the redirection transaction of the HTTP protocol, and a name server based on the HIND. The paper shows how the interaction between the domain mapper and the name sever can make forwarding possible and describes its implementation in detail. Experimental results shows that the overhead incurred by URL forwarding is negligible compared to the typical delay of current Internet traffic condition.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.3
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• pp.193-204
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• 2006

In most existing distributed Web systems, incoming requests are distributed to servers via Domain Name System (DNS). Although such systems are simple to implement, the address caching mechanism easily results in load unbalancing among servers. Moreover, modification of the DNS is necessary to load considering the server's state. In this paper, we propose a new dynamic load balancing method using dynamic DNS update and round-robin mechanism. The proposed method performs effective load balancing without modification of the DNS. In this method, a server can dynamically be added to or removed from the DNS list according to the server's load. By removing the overloaded server from the DNS list, the response time becomes faster. For dynamic scheduling, we propose a scheduling algorithm that considers the CPU, memory, and network usage. We can select a scheduling policy based on resources usage. The proposed system can easily be managed by a GUI-based management tool. Experiments show that modules implemented in this paper have low impact on the proposed system. Furthermore, experiments show that both the response time and the file transfer rate of the proposed system are faster than those of a pure Round-Robin DNS.