• Journal of Computing Science and Engineering
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• v.11 no.3
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• pp.92-99
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• 2017

Memcached, commonly used to speed up the data access in big-data and Internet-web applications, is a system software of the distributed-cache mechanism. But it is subject to the severe challenge of the loss of recently uncommitted updates in the case where the Memcached servers crash due to some reason. Although the replica scheme and the disk-log-based replay mechanism have been proposed to overcome this problem, they generate either the overhead of the replica synchronization or the persistent-storage overhead that is caused by flushing related logs. This paper proposes a scheme of backing up the write requests (i.e., set and add) on the Memcached client side, to reduce the overhead resulting from the making of disk-log records or performing the replica consistency. If the Memcached server fails, a timestamp-based recovery mechanism is then introduced to replay the write requests (buffered by relevant clients), for regaining the lost-data updates on the rebooted Memcached server, thereby meeting the data-consistency requirement. More importantly, compared with the mechanism of logging the write requests to the persistent storage of the master server and the server-replication scheme, the newly proposed approach of backing up the logs on the client side can greatly decrease the time overhead by up to 116.8% when processing the write workloads.

• Journal of the Korean Society of Systems Engineering
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• v.2 no.2
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• pp.45-50
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• 2006

Tilting technology is to tilt the train on the curve in order to minimize centrifugal force to passengers and to improve the speed within the limits of passenger's comfort and safety. According to reports from other countries, there is 15~30% speed improvement compared to the conventional trains. Recently, the advent of World-Wide-Web(WWW) and the explosive popularity of the Internet gave birth to collaborative applications which were enabled by computers and networks as their primary media. The progress of 3D computer graphics enabled collaborative applications with 3D virtual environments or distributed virtual environments. In this paper, we explain our implementation of the Share collaboration engine which is for collaboration applications based on a distributed virtual environment. The Share collaboration engine proposes a new Share network architecture for management of participants, and it provides some synchronization methods for 3D objects in virtual collaboration. TTX_PDM is an experimental application that tries to prevent wastes of human, material and time resources in networked virtual collaboration.

• The KIPS Transactions:PartB
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• v.10B no.1
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• pp.111-118
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• 2003

The SMIL specification that is recently approved by the W3C and is meant to help deliver multimedia content to the Web, is widely used in these days and they have continuously emerged tools or softwares related with that. In this paper, I propose an algorithm to convert temporal scripts of RASP that is an experimental toolkit for computer animation that promotes interaction-based programming over time into a SMIL document. For making better use of SMIL documents, we can improve reusability of animation components. And, main contribution of this paper is that it verifies the sequence diagram generated for synchronization of documents by reconverting SMIL from UML sequence diagram.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1707-1710
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• 2015

Energy Management System(EMS)는 전력 시스템에서 운영자에 의해 발전과 송전의 성능을 감시 제어 그리고 성능 최적화를 위하여 운영하는 시스템이다. 본 연구에서는 EMS(Next Generation Energy management System : NG-EMS)에서 클라이언트의 운영 시스템 자동 동기방법 및 웹 기반 온라인에서 뷰어를 실행, 운영하는 방법을 제안 한다. 본 연구는 인트라넷 망에서 클라이언트 운영 시스템의 효율적인 유지보수를 위하여 소프트웨어 패치 및 엔지니어링을 통해 도출된 그래픽 화면을 다수의 클라이언트에 자동 동기, 갱신하는 기능을 특징으로 한다. 또한 자동 동기 빌더를 사용하여 클라이언트에 동기 할 항목을 패키징하는 기능도 포함하고 있다. 자동 동기 서버 측에서는 본 연구의 구성에 의해 클라이언트의 동기 및 갱신 주기를 효율적으로 관리한다. 클라이언트가 메인서버로 접속할 시 자동동기 상태를 체크하는 서버에 문제가 발생했을 경우 다중 동기 서버 형태로 운영하여 불시 장애 발생에 효율적으로 대처가 가능하다. 또한 자동동기 시스템을 적용한 웹 기반 온라인 뷰어의 운영 시스템 및 방법을 제안한다.

• Journal of Digital Convergence
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• v.17 no.11
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• pp.435-440
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• 2019

Recently, many musical instrument mobile apps have been released targeting normal people who can't play musical instrument at all. The reason of developing video system based on step sequencer are as follows; first, users can freely play the musical instruments; second, induce multiple users to play; and third, develop and suggest new step sequencer fused with the video. To resolve issue in video synchronization caused by sync issues when operating multiple step sequencers, the Pocket Operator of Teenage Engineering was used to realize multiply-connected step sequencer and also, the ultimate video system was developed through Mira-Web for multiple participation. In addition, it's required to make the Pocket Operator as software and receive various feedbacks to continue and complement study in order to develop the better video system.

• Journal of Internet Computing and Services
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• v.17 no.6
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• pp.71-79
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• 2016

As computer technology continues to evolve, the Computational Sciences utilized in Physics, Chemistry, Materials Science, and Life Sciences have been attracting more attention. In Korea, to compensate for the drawbacks in Computational Science, students and researchers have been using the EDISON platform. The EDISON platform provides a web portal service for education and research and an environment for addressing complex issues involving five fields, e.g., Computational Fluid Dynamics (CFD), Nanophysics, Computational Chemistry, Structural Dynamics, and Computational Design. As the platform and user scale increase beyond service provision, the need for efficient operation of its currently running data management system is on the rise. In this study, we resolve the data synchronization issues between the existing EDISON platform and web portal. As the EDISON platform is integrated with the web portal, a file management service is implemented to integrate the management of user data and files, which ultimately improves the overall efficiency of file management.

• The KIPS Transactions:PartD
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• v.10D no.3
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• pp.513-520
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• 2003

In order to represent a play script using XML, a DTD has been defined and used on the web. However, it is not easy to make XML scripts using text editors for a writer who is not familiar with XML. Moreover, editors do not help actor/actresses use XML scripts for practicing plays. In this research, we develop a syntax-directed XML editor designed for writing XML scripts easily. Also, we implement a system that help actor/actresses practice plays together with multi-clients. Play events are synchronized by a time server synchronizing clocks of participants. We have evaluated the performance of various event implementation techniques through experiments and have used an appropriate technique for synchronizing play events. By using the system, a play writer can easily make an XML script and actor/actresses practice the play using the script.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.8
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• pp.293-298
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• 2014

Detecting and understanding the changes between RDF data is crucial in the evolutionary process, synchronization system, and versioning system on the web of data. However, current researches on detecting changes still remain unsatisfactory in that they did neither consider the large scale of RDF data nor accurately produce the RDF deltas. In this paper, we propose a scalable and effective change detection using a MapReduce framework which has been used in many fields to process and analyze large volumes of data. In particular, we focus on the structure-based change detection that adopts a strategy for the comparison of blank nodes in RDF data. To achieve this, we employ a method which is composed of two MapReduce jobs. First job partitions the triples with blank nodes by grouping each triple with the same blank node ID and then computes the incoming path to the blank node. Second job partitions the triples with the same path and matchs blank nodes with the Hungarian method. In experiments, we show that our approach is more accurate and effective than the previous approach.

• Journal of the Korea Society of Computer and Information
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• v.17 no.10
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• pp.137-143
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• 2012

The learners using learning content through the smart devices can access to the Internet from anytime and anywhere. However, with the rapid increase of learning content on the Web, it will be time-consuming for learners to find contents they really want to and need to study. Therefore, e-learning systems should not only provide flexible content delivery, but support adaptive harmonizing fusion content. The harmonizing fusion content it is a very important in fusion e-learning service. The representative method to provide synchronization between fusion content is a provide absolute time value between of the contents. However, this method is occurs a problem transferring time delay. Also, to enter an absolute time value for the duration of the each content is several problems arise. In this paper introduces a new smart e-smart service support the harmonizing media based technology to create synchronized learning presentation.

• Journal of Broadcast Engineering
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• v.21 no.5
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• pp.651-661
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• 2016

최근의 디지털 사이니지는 대형 고해상도 디스플레이를 이용해 사용자에게 초고해상도 파노라마형태의 볼거리를 제공하거나 사용자와 인터렉션 등을 통해 맞춤형광고를 제공하는 등 다양한 형태로 발전하고 있다. 또 개방형 디지털 사이니지의 발전과 함께 대형 멀티 사이니지를 이용한 초고화질 영상콘텐츠를 다양한 서비스 단말장치의 연동과 웹기반의 상호운용성을 갖춘 관리시스템이 활발히 연구될 것으로 보인다. 본 논문에서는 수십대에서 백여대 이상의 고해상도 디스플레이를 연동하여 초고해상도 영상표출의 기술의 구현방안과 정형화된 영상 해상도가 아닌 초고화질 영상의 개별 콘텐츠에 대한 동기화 시키는 기술을 이용하여 멀티 콘텐츠 플레이 단말기에서 고해상도 영상을 Play Sync하는 기술을 연구한다.