• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.1092-1100
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• 2012

In this paper, it has designed and developed the integrated aural cueing system(ACS) system of the reconfigurable tactical Flight Training System(RTT) for the 6 rotorcraft such as UH-1H, UH-60, AH-1H, 500MD, BO-100, and CH-47. RTT is an evolving alternative instructional training system to provide the ability to rehearsal and collectively train, through networked simulators in a unit-collective and combined arms simulated battlefield environment. ACS handles the volume, pitch and repetition of the digitally stored sounds based on commands it receives from the Host server. This paper explained and implemented the conceptual and detail design the ACS system. In order to evaluating the performance of the ACS system, we made the monitoring system for interworking the virtual Host and the ACS system. As the result, it was confirmed the good performance.

• Journal of Korea Multimedia Society
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• v.2 no.3
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• pp.265-276
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• 1999

Video on Demand (VOD) system is definitely one of main applications in upcoming multimedia era. In this research, we have designed and implemented a host-based scalable VOD system (SVOD) which is composed of low cost PC servers and runs on Linux kernel that is currently spotlighted in enterprise and research domains. Our contribution is as follows: first, the previous Ext2 file system was modified to efficiently support continuous media like MPEG stream. Second, the storage server features a host-based scalable architecture. Third, a software MPEG decoder was implemented using Microsoft's DirectShow$\circledR$COM. Finally, flow control between client and server is provided to suppress overflow and underflow of client circular buffer and supports FF VCR operation. We have known that it is possible to develop a thread-based and scalable VOD system on low cost PC servers and free Linux kernel.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.565-572
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• 2001

Recently, due to the open architecture of the internet and wide spread of internet users, the cyber terror threatens to the network\`s weak point are tending grow. Until now, information security solutions are passive on security host and particular security system. This passive information security solution is weak from the attacks through the networks connected worldwide internet systems, and has limitation on the defense against cyber terror attacks. Therefore, network level integrated security function must be provided. In this paper, we consider technology limitations on the information security problems and its environment. Then we present the architecture and functions of policy-based information security services for network level active information security function. This paper also includes design of target system, which provide information security services. Finally, we discuss network level system deployment direction and discuss with Network Security Simulation.

• KIISE Transactions on Computing Practices
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• v.24 no.3
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• pp.129-137
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• 2018

NVMe(Non-Volatile Memory Express) SSD(Solid State Drive) is a high-performance storage that makes use of flash memory as a storage cell, PCIe as an interface and NVMe as a protocol on the interface. It supports multiple I/O queues which makes it feasible to process parallel-I/Os on multi-core environments and to provide higher bandwidth than SATA SSDs. Hence, NVMe SSD is considered as a next generation-storage for data-center and cloud computing system. However, in the virtualization system, the performance of NVMe SSD is not fully utilized due to the bottleneck of the software I/O stack. Especially, when it uses I/O stack of the hypervisor or the host operating system like Xen and KVM, I/O performance degrades seriously due to doubled-I/O stack between host and virtual machine. In this paper, we propose a new I/O engine, called Direct-AIO (Direct-Asynchronous I/O) engine, that can access NVMe SSD directly for I/O performance improvements on QEMU emulator. We develop our proposed I/O engine and analyze I/O performance differences between the existed I/O engine and Direct-AIO engine.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.782-785
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• 2007

If existing system need to expand security part, the security was established after paying much cost, processing of complicated installation and being patient with inconvenience at user's view because of closed structure. In this thesis, those defects could be overcome by using open security tools and constructing security server, which is firewall of 'bastion' form including proxy server, certification server and so on. Also each security object host comes to decide acceptance or denial where each packet comes from, then determines security level each hosts. Precisely it is possible choosing the packets from bastion host or following at the other policies. Although an intruder enter into inside directly, it is constructed safely because encryption algorithm is applied at communication with security object host. This thesis suggests more flexible, independent and open security system, which improves existing security through systematic linkage between system security and network security.

• The KIPS Transactions:PartD
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• v.11D no.3
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• pp.605-616
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• 2004

The purpose of CBSD(Component Based Software Development) if to develop software using a reuse component and components assembly. The reused components have to be adapter for satisfaction of requirement specification. This paper represents a component adaption method which reuse previously developed component or legacy system, using an adaptation component called by TA(Transaction Adaptor). The adaptation using TA transmits XML data that is translated into stream type, from a client to on host system. And we introduce RS(Rule Server) which gets some Information from XML data for application program development. Through the Interaction of TA and RS, we can improve effectiveness of component development and maintenance and we can reuse legacy system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.643-650
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• 2008

If existing system need to expand security part, the security was established after paying much cost, processing of complicated installation and being patient with inconvenience at user's view because of closed structure. In this thesis, those defects could be overcome by using open security tools and constructing security server, which is firewall of 'bastion' form including proxy server, certification server and so on. Also each security object host comes to decide acceptance or denial where each packet comes from, then determines security level each hosts. Precisely it is possible choosing the packets from bastion host or following at the other policies. Although an intruder enter into inside directly, it is constructed safely because encryption algorithm is applied at communication with security object host. This thesis suggests more flexible, independent and open security system, which improves existing security through systematic linkage between system security and network security.

• Journal of KIISE:Databases
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• v.32 no.1
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• pp.56-70
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• 2005

The results of location-dependent queries(LDQ) generally depend on the current locations of query issuers. Many mechanisms, e.g. broadcast scheme, hoarding, or racking policy, have been developed to improve the system peformance and provide better services, which are specialized for LDQs. Considering geographical adjacency of data and characteristics oi target area, caching policy and broadcast scheme affect the overall performance in LDQ. For this reason, we propose both the caching policy and broadcast scheme, which these features are reflected in. Based on the adjacency of data in LDQ, our broadcast scheme use Hilbert curve to cluster data. Moreover, in order to develop the caching policy suitable for LDQ on urban area, we apply the moving distance of a MH(Mobile Host) to our caching policy We evaluate the performance of the caching policy measuring the workload of MHs and the correctness of LDQ results and the performance of the broadcast scheme measuring the average setup-time of MHs in our experiments. Finally, we expect that our caching policy Provides more correct answers when executing LDQ in focal cache and leads significant improvement of the performance of MHs. It also seems quite probable that our broadcast scheme leads improvement of battery life of the MH.

• Journal of Intelligence and Information Systems
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• v.27 no.3
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• pp.1-27
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• 2021

The entire tourism industry is being hit hard by the COVID-19 as a global pandemic. Accommodation sharing services such as Airbnb, which have recently expanded due to the spread of the sharing economy, are particularly affected by the pandemic because transactions are made based on trust and communication between consumer and supplier. As the pandemic situation changes individuals' perceptions and behavior of travel, strategies for the recovery of the tourism industry have been discussed. However, since most studies present macro strategies in terms of traditional lodging providers and the government, there is a significant lack of discussion on differentiated pandemic response strategies considering the peculiarity of the sharing economy centered on peer-to-peer transactions. This study discusses the marketing strategy for individual hosts of Airbnb during COVID-19. We empirically analyze the effect of changes in listing descriptions posted by the Airbnb hosts on listing performance after COVID-19 was outbroken. We extract nine aspects described in the listing descriptions using the Attention-Based Aspect Extraction model, which is a deep learning-based aspect extraction method. We model the effect of aspect changes on listing performance after the COVID-19 by observing the frequency of each aspect appeared in the text. In addition, we compare those effects across the types of Airbnb listing. Through this, this study presents an idea for a pandemic crisis response strategy that individual service providers of accommodation sharing services can take depending on the listing type.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.616-618
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• 2001

협력 시스템은 분산 시스템 환경에서 호스트들이 네트워크를 통하여 상호 연결되어 있으며 다양한 사용자가 여러 자원들 공동으로 활용한다. 협력 시스템 발전 및 정보 보안의 중요성에 대한 인식 증가로 인하여, 개방형 분산 협력 시스템 환경에서도 정보 통신 시스템의 자원을 보호하기 위한 여러 가지의 보안 서비스에 대한 연구가 진행되고 있다. 하지만 기존의 일반적인 보안 서비스로는 협력 시스템에 특징과 구조에 맞는 서비스를 제공하기 어려운 점이 있다. 본 논문에서는 저자가 개발한 산업 디자인 협력 시스템에서의 보안 프레임워크를 제안한다. 제안된 프레임워크는 인증, 암호와 정잭, 접근제어, 보안 정보 관리의 네 가지로 구분하며 각각의 서비스가 상호 보완적으로 구성되어 있다. 또한, 특정 협력 시스템에 맞도록 구성되었지만 다른 협력 시스템에도 응용할 수 있도록 표준화를 따랐으며, 사용자의 요구에 따라 다른 비밀성과 투결성을 지원하기 위한 QoP(Quality of Protection) 서비스도 고려하여 설계하였다. 제안된 보안 프레임워크는 접근제어 요소를 협력 시스템의 구성에 맞도록 재구성하여 기존 정책의 단점인 복합적인 상황에서 확실한 보안을 할 수 있었으며 접근 정의에 따라 다른 알고리즘을 사용함으로 보안 프레임워크가 포함된 후에도 빠른 협력 작업이 가능했다. 또한 디자인 협력 시스템의 동시성 제어 정책을 기반으로 접근 제어 정책을 결정하였기 때문에 시스템 성능에 향상을 가지고 왔다.