• Proceedings of the Safety Management and Science Conference
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• 2009.11a
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• pp.411-415
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• 2009

There are some definitions of cloud computing but it can be defined as utilization of personal computers, servers and softwares in one cluster for approaches to the use of shared computing resources. Nowadays the applications of cloud computing are rapidly increasing because of its merits on economic aspect, connectivity convenience, storage space and so on. The main objective of this paper is to find an effective methodology as an initial stage for applications of cloud computing in a real life. Therefore this paper addresses worldwide reviews on cloud computing.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.118-123
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• 2022

We implemented a real-time cloud robotics application by offloading robot navigation engine over to 5G Mobile Edge Computing (MEC) sever. We also ran a fleet management system (FMS) in the server and controlled the movements of multiple robots at the same time. The mobile robots under the test were connected to the server through 5G SA network. Public 5G network, which is already commercialized, has been temporarily modified to support this validation by the network operator. Robot engines are containerized based on micro-service architecture and have been deployed using Kubernetes - a container orchestration tool. We successfully demonstrated that mobile robots are able to avoid obstacles in real-time when the engines are remotely running in 5G MEC server. Test results are compared with 5G Public Cloud and 4G (LTE) Public Cloud as well.

• The Transactions of the Korea Information Processing Society
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• v.4 no.5
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• pp.1358-1370
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• 1997

Client-Sever-Comptuing is now recognized as the most powerful and flexible computing mode of the future.Many companies have already commited significant amount of their corporate IS resources to building the cli-ent-server computing environment.Despite this active interst and commitment,however,results from such cli-ent-sever projects are far from being convincing Among the many factors,we suspect,we supect that the less than less than satisfac-tory client-server experiences are perhaps due to the company's lack of underxtanding its essertial information processing characteristics.We analyze five client-server archiedctures in temrs of seven IS-related crieria.We then develop a contin-gency model to match company's information processing chracteristics to the ideal client-server architecture for the firm.Based on the client-server architecture analysis from the previous step. we recommend specific im-plementation strategies for each-server architecture selected. Finally,on an exploratory level,we look into the three client-server implmentation cases to cases to check the validity of our contingency model.

• Journal of Korea Multimedia Society
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• v.8 no.8
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• pp.1088-1098
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• 2005

Context-Aware is a one of the important researches in ubiquitous computing for providing optimal service to users by acquiring user's intentions and environmental information. Diverse researches are focused on the users and its environment facts for Context-Aware base and introduce a sensing based middleware which engages sever/sensor that operates identifier information to provide services. Context-Aware service which is limited by users and environment facts has the problem of overlapping sensing, unnecessary searching and anonymity of users. Also Server-Centric Context-Aware system requires very high cost to manage and operate the services. On this paper, We introduce Autogenous Context service model to simplify the Context-Aware process and design the middleware which performs decentralize management for Context-Aware information of user's portable devices to minimize problems which is occurred during the management and operation of existing Context-Aware system.

• Journal of Internet Computing and Services
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• v.12 no.2
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• pp.29-36
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• 2011

In this paper, NMEA based Parser programming for Smart-phone was designed at a GPS receiver. The design scheme for Map API and sensor web services was designed according to the Google Map API standards that the position values of NMEA sentences were changed due to XML files. As a result of interfaces between GPS NMEA sentences of Smart-phone and Google Map API, it is possible that real time visual positioning sensor web services about the Google Map mapping from a GPS receiver could be worked on web sever.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.635-642
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• 2003

The radical development of recent network technology provides the basic foundation which can establish a high speed and cheap cluster system. It is a general trend that conventional cluster systems are built as the system over a fixed level based on stabilized and high speed local networks. A multi-distributed web cluster group is a web cluster model which can obtain high performance, high efficiency and high availability through mutual cooperative works between effective job division and system nodes through parallel performance of a given work and shared memory of SC-Server with low price and low speed system nodes on networks. For this, multi-distributed web cluster group builds a sub-cluster group bound with single imaginary networks of multiple system nodes and uses the web distributed shared memory of system nodes for the effective data transmission within sub-cluster groups. Since the presented model uses a load balancing and parallel computing method of large-scale work required from users, it can maximize the processing efficiency.

• Journal of Internet Computing and Services
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• v.3 no.1
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• pp.91-99
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• 2002

Many companies and departments are increasingly concerned of searching their business information in correct and faster way as they share the information through the internet. LDAP has been proposed for directory server standards which supports storing, searching and managing the business information, and it has become a global standard. Current LDAP, however, cannot solve problem; such as server overloads and data synchronization. This paper describes the history and characteristics of LDAP, and proposes an architecture for solving those problem;. Since the proposed architecture is designed based on the existing LDAP architecture, it guarantees extensibility and portability of server configuration.

• Journal of KIISE:Software and Applications
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• v.26 no.8
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• pp.974-987
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• 1999

이동 컴퓨팅 환경에서 자주 접근하는 데이터에 대한 캐싱은 무선 채널의 좁은 대역폭에서 경쟁을 줄일 수 있는 유용한 기술이다. 그러나, 트랜잭션 캐시 일관성을 지원하는 전통적인 클라이언트/서버 전략은 클라이언트와 서버간에 많은 양의 통신을 필요로 하기 때문에 이동 클라이언트/서버 컴퓨팅 환경에서는 적절하지 않다. 본 논문에서는 브로드캐스트-기반 캐시 무효화 정책을 사용하면서 트랜잭션 캐시 일관성을 지원하는 OCC-UTS (Optimistic Concurrency Control with Update TimeStamp) 프로토콜을 제안한다. 접근한 데이터에 대한 일관성 검사 및 완료 프로토콜은 캐시 무효화 과정의 내부 과정으로 완전 분산 형태로 효율적으로 구현되며, 일관성 체크의 대부분이 이동 클라이언트에서 수행된다. 또한, 분석 모델에 기반한 성능 비교를 통해, 본 논문에서 제안하는 OCC-UTS 프로토콜이 다른 경쟁 프로토콜보다 높은 트랜잭션 처리율을 얻으며, 데이터 항목을 자주 접근하면 할수록 지역 캐시를 사용하는 OCC-UTS 프로토콜이 더 효율적임을 보인다. 이동 클라이언트의 접속 단절에 대해서는 무효화 브로드캐스트 윈도우를 크게 하여 접속 단절에 적절히 대처할 수 있다.Abstract In a mobile computing environment, caching of frequently accessed data has been shown to be a useful technique for reducing contention on the narrow bandwidth of the wireless channels. However, the traditional client/server strategies for supporting transactional cache consistency that require extensive communications between a client and a server are not appropriate in a mobile client/server computing environment. In this paper, we propose a new protocol, called OCC-UTS (Optimisitic Concurrency Control with Update TimeStamp), to support transactional cache consistency in a mobile client/server computing environment by utilizing the broadcast-based solutions for the problem of invalidating caches. The consistency check on accessed data and the commitment protocol are implemented in a truly distributed fashion as an integral part of cache invalidation process, with most burden of consistency check being downloaded to mobile clients. Also, our experiments based on an analytical model substantiate the basic idea and study the performance characteristics. Experimental results show that OCC-UTS protocol without local cache outperforms other competitor protocol, and the more frequent a mobile client accesses data items the more efficient OCC-UTS protocol with local cache is. With respect to disconnection, the tolerance to disconnection is improved if the invalidation broadcast window size is extended.

• Journal of Internet Computing and Services
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• v.17 no.4
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• pp.19-26
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• 2016

In this paper, the dynamic buffering based smart OTT platform was proposed, and analyzed for adaptive bit-rate video delivery with the optimization of HLS (HTTP Live Streaming). This platform consists of the software platform between sever and client which detects the bandwidth capacity, and adjusts the quality of the streaming for multiple bit-rates resolutions. In order to apply adaptive buffering, two buffers are added to the basic HLS player, and each buffer is responsible for constantly buffering a previous and the next channels relative to the current channel. This adaptive transmitting with smart OTT platform is superior to delivering a static video file at a single buffering, because the video stream of adaptive double buffers can be switched streaming according to client's available network speed. As a result, this proposed smart OTT can be cooperated to the application of HLS server with segmented H.265 MPEG-2 TS video & m3u8 files with its information based on the optimized transmission channel state of live and VOD, and applied to PLC transmission, too.

• Journal of KIISE:Databases
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• v.32 no.3
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• pp.276-284
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• 2005

In the mobile computing environment, caching data at the client's side is a useful technique for improving the performance. For caching to be effective, the cache contents must be consistent with those stored in the server. That is, unfortunately, difficult to enforce due to the frequent disconnection and mobility of clients. In the literature, the basic approach adopted is for the sever to periodically broadcast invalidation reports(IRs) that contain information about objects that have been updated recently. However IR-based cache maintenance scheme has a main drawback. Any client who has been disconnected longer than w seconds has to discard all cached items even some of them may still be valid. In this paper, we propose two main schemes which can adapt clients' losing IR messages by long disconnection. First, the client sends its disconnection time when connection is re-established, and the server uses this information to decide the size of broadcast window w dynamically. Second, the server maintains IR messages for a given period of time and a client who has been disconnected longer than w seconds can verify its cache consistency individually. Compared to previous IR-based schemes, our schemes can significantly reduce cache missing and uplink request and improve the throughput by reducing response time.