• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.370-372
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• 2003

본 논문은 GRID 상에서 HLA(High Level Architecture)를 기반으로 한 분산 객체 지향 simulation을 위한 네트워크 하부구조인 Run-Time Infrastructure (이하 RTI)의 디자인과 구현에 관해 기술한다. RTI는 지리적으로 떨어진 응용 프로그램간의 정보 교환 외에도, 접속 사양에 정의된 다양한 서비스를 제공하는 middleware이다. GRID는 전세계에 펼쳐져 있는 자원들에 대한 관리와 접근, 사용을 위한 다양한 기능과 안전하고 편리한 security를 보장한다. 본 논문에서는 globus toolkit에서 지원하는 security와 자원 접근 방법을 사용해서 RTI에 보안과 자원의 동적 할당을 부여해서 RTI를 이용한 simulation에 뛰어난 상호 연동 능력과 대규모의 프로젝트를 위한 광범위한 자원을 보다 안전하고 효율적으로 사용할 수 있도록 하는 환경을 구현하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.31-33
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• 2004

HLA (High Level Architecture) 는 모델링과 시뮬레이션 분야에서 상호 이질적인 서비스에 따른 어플리케이션의 상호운용성(interoperability)과 재사용성(reusability)을 증진시키기 위해 필요한 infrastructure를 개발하기 위한 청사진이다. RTI(RunTime Infrastructure)는 HLA 의 소프트웨어적 도구로써 IibTRI, FedExec, RTIExec의 세 가지 컴포넌트로 구성되어 있다. RTI는 분산환경에서 동적으로 다수대다수간의 통신을 제공하는 미들웨어 (middleware)이다. 대규모의 분산 시뮬레이션의 실행은 지리적으로 퍼져있는 많은 양의 컴퓨팅 자원을 필요로 할 수 있는데 이러한 환경이 가지는 보안과 동적 자원 할당이라는 문제점을 Globus Toolkit3(GT3)안의 Open Grid Service Arcitecture(OGSA)를 사용해서 해결할 수 있는 RTI-G를 개발해 왔고 이를 service-oriented RTI-G라 부른다. 이 논문에서는 service-oriented RTI on Grid 의 구조와 앞에 제시된 문제점들의 해결방안을 제시하고 실험한다.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.3
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• pp.211-227
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• 2012

To implement a combined discrete event and discrete time simulation such as submarine diving simulation in a distributed environment, e.g., in the High Level Architecture (HLA)/Run-Time Infrastructure (RTI), a HLA interface, which can easily connect combined models with the HLA/RTI, was developed in this study. To verify the function and performance of the HLA interface, it was applied to the submarine dive scenario in a distributed environment, and the distributed simulation shows the same results as the stand-alone simulation. Finally, by adding a visualization model to the simulation and by editing this model, we can confirm that the HLA interface can provide user-friendly functions such as adding new model and editing a model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.749-752
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• 2003

The HLA is defined by three components: (1) Rules, (2) the HLA Interface Specification, and (3) the Object Model Template(OMT). The RTI(Run-Time Infrastructure) software implements the interface specification. It provides services in a manner that is comparable to the way a distributed operating system provides services to applications. A way to test whether is suitable for a standard, and all service was implemented is tested through two phases of processes to verify the RTI which proposed in DMSO. In this paper, we discuss Level One Test Procedures and a method. Confirms whether RTI was implemented in Interface Specification according to Level One Test Procedures appropriately through a test. Develops Test Suite for every each step to test whether a correct command and the expected results are occur.

• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.43-52
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• 2008

The High Level Architecture(HLA) is the IEEE 1516 standard for interoperation between heterogeneous simulators which are developed with different languages and platforms. Run-Time Infrastructure(RTI) is a software which implements the HLA Interface Specification. With the development of time management service of RTI, it is necessary to consider an efficient design approach and an algorithm of Greatest Available Logical Time(GALT) computation. However, many time management services of existing RTIs have difficulty in modification and extension. Although some RTIs avoid this difficulty through modular design, they comply with not IEEE 1516 HLA/RTI but HLA 1.3. In addition, a lot of RTIs made use of well-known Mattern's algorithm for GALT computation. However, Mattern's algorithm has a few limitations for applying to IEEE 1516 HLA/RTI. This paper proposes a modular design and an implementation of time management service for IEEE 1516 HLA/RTI. We divided th time management service module into two sub-modules: a TIME module and a GALT module and used Mattern's algorithm improved for IEEE 1516 HLARTI. The paper also contains several experimental results in order to evaluate our time management service module.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1227-1234
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• 2011

Korea is a mountainous country, with as much as 70% of the area is covered by hills and mountains. This geography places constraints on the minimum radius of curvature for the rail network. It was expected that the speed of trains could be enhanced on the existing railway network without a huge investment in infrastructure by using tilting trains. The development of tilting trains in Korea started in 2001 as research & development project. A 6-car prototype test tilting train, called the Tilting Train eXpress (TTX), was built in December 2006 and experimental trials began in 2007. TTX has distributed power, is designed to run at 200 km/h, and has a planned service speed of 180 km/h. In this paper, we first describe the performance of tilting train, and then present the estimated running times, and the time saving compared with today's conventional trains and non-tilting trains, based on the Jungang line. So the time saving could be separated into two effects by higher track top-speed and tilting devices.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.573-581
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• 2021

The current study analyzed the impacts of fiscal decentralization (FD) on the economic stability of Pakistan. This study used time series data from 1981 to 2017. The collected data was first passed through the unit root analysis. ARDL estimation techniques were employed to scrutinize the data where long-run associations were tested through Wald F-statistics. The long-run estimates were extracted by applying Ordinary Least Square, and error correction mechanisms were employed to find the speed of adjustment for disequilibria between the long and the short run. Wald F-statistics confirmed the existence of long-run cointegration. Long-run elasticities suggested that fiscal decentralization because of limited institutional capabilities of provincial governments failed in bringing stability in the economy of Pakistan. Similarly, transparency issues and misspecification of projects hinder the outcome of investment to stabilize the economy. High service payments on debt cut the amount that can be used for skills improvements and destabilize the economy. High Population growth puts pressure on infrastructure and reduces production capacity, ultimately destabilizing the economy by increasing unemployment and inflation. Based on these findings, the government is suggested to improve the institutional capacity of lower governments for the desired outcome of power devolution.

• The KIPS Transactions:PartD
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• v.9D no.6
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• pp.1137-1144
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• 2002

Possibility of federation improvement requires flexibility and adaptability of member federates. Moreover, to develop and convert a non-HLA(High Level Architecture) compliant model as a HLA federate and allow this federate to be integrated with a changeable federation, more time and efforts will be necessary. In this research, I proposed a method to design and implement a ROM (RTI Object Model) Framework as a solution to this problem. ROM completely separates RTI (Run-Time Infrastructure) programming and simulation programming therefore providing epochal efficiencies in cost and productivity to the development a HLA federate that supports a changeable FOM. That is, ROM contains two layers : 1) a management layer that manages RTI services between the RTI and the federate and 2) a Foundation Class layer that actually updates/reflects objects and interactions. These two layers allow federate developers to use more generalized HLA services and automates the iterative, low-level RTI programming process.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.164-168
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• 1999

HLA(High Level Architecture)는 분산 시뮬레이션의 표준화를 위한 개념적인 분산 시스템 프레임워크이며, RTI(Run Time Infrastructure)는 HLA를 따르는 분산 시뮬레이션들을 위한 네트워크 하부구조이다. 분산 시뮬레이션은 분산 노드간에 효율적이고 인과 오류가 없는 통신 방법의 지원이 필수적이며, RTI는 시뮬레이션에 참여하는 분산 노드간 메시지 전송을 위하여 최선(best-effort) 전송 서비스와 신뢰(reliable) 전송 서비스를 규정하고 있다. RTI의 메시지 전송 서비스는 기본적으로 메시지 전송 과정에서 메시기간 인과 관계를 유지해야 하는 다자간 통신 서비스이며, 본 논문에서는 인터넷상에서 인과 오류가 없는 다자간 통신을 위한 새로운 형식의 분산 시스템 구조를 제안하고, 성능 평가를 위한 실험 결과를 소개한다.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.11a
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• pp.85-89
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• 2002

Development of distributed simulation environment must be required in order to simulate the distributed models regionally and inter-operate with running simulations individually, Simulation based on DEVS formalism is difficult to simulate the distributed models. DEVS formalism is modeling methodology. To specify model, this formalism separates behavior and structure, therefore it is able to design complex model easily. HLA is standard framework of distribute simulation environment, It is defined to facilitate the interoperability and the reusability. RTI (Run Time Infrastructure) is software that provides common service to simulation systems and implementation of the HLA Interface Specification. Method of implementation is that modules cooperating with RTI are added to simulator on DEVS simulation environment. On the DEVS simulation environment (DEVS-Obj -C) that already developed, Highest class of abstract simulator uses service that RTI provide, then This environment is able to change DEVS model into Federate and run distribute simulation that inter-operates with the RTI. Because this distributed simulation environment includes convenience of modeling that obtains through the DEVS formalism and accompanies HLA standard, this environment make it possible to simulate with_ complex systems and heterogeneous simulations