• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2002.12a
• /
• pp.375-378
• /
• 2002

In this paper we propose parallel GA to optimize mutation rate and crossover rate using server-client model. The performance of GA depend on the good choice of crossover and mutation rates. Although many researcher has been study about the good choice, it is still unsolved problem. proposed GA optimize crossover and mutation rates trough evolving subpopulation. In virtue of the server-client model, these parameters can be evolved rapidly with relatively low-grade

• Journal of Korean Institute of Industrial Engineers
• /
• v.16 no.1
• /
• pp.107-114
• /
• 1990

A queueing system with compound Poisson arrival and server vacation is analyzed by including supplementary variables. We consider a vacation system in which the server leaves for a vacation as soon as the system empties. When he returns, if no customer is waiting for service, he waits until a group of customers arrive and then begins to serve. We obtain the system size distribution and the waiting time distribution. Additional performance measures will be also considered.

• Journal of information and communication convergence engineering
• /
• v.3 no.2
• /
• pp.93-95
• /
• 2005

In order to create security session, security keys are preconfigured between communication objects. For this purpose, Handshake Protocol exists. The pre-master secret key that is used in this process needs to interpreted by a server to create master secret key, whose process requires a big calculation, resulting in deteriorating system's transmission performance. Therefore, it is helpful in increasing transmission speed to reuse secret keys rather than to create them at every connection.

• Proceedings of the KIEE Conference
• /
• 2003.11c
• /
• pp.868-870
• /
• 2003

In this paper, I have implemented the security system using shell script that periodically checking the security elements of unix system for security it transmit to a monitoring server and monitoring many clients. Agent of client executing by crontab scheduler, Environment of server to receive data use restricted TFTP in SunOS. And then, Because of using shell script, apply shell to system with flexible, control performance, and can meet on a sudden situation.

• Annual Conference of KIPS
• /
• 2020.11a
• /
• pp.694-697
• /
• 2020

본 논문은 언리얼 엔진에서 제공하는 Dedicated server를 사용하지 않고 자체적으로 제작한 IOCP모델 서버를 구축하고, 이를 언리얼 클라이언트와 MySQL데이터베이스에 연동하여, 완성된 서버의 성능 테스트를 진행한 결과를 보였다.

• Journal of Internet Computing and Services
• /
• v.5 no.3
• /
• pp.99-108
• /
• 2004

We have designed and implemented a Voice Messenger System(VMS) for sending and receiving voice data in order to measure and analyze the performance of a multimedia data transfer system using PDAs(Personal Digital Assistants) in a fast wireless LAN environment. The VMS has been configured as an infrastructure network by integrating a wireless intra-network based on IEEE 802,11 b standard with a wired network based on Ethernet. A sending time, a receiving time and a round-trip time(RTT) have been measured by varying its pecket size from 256 to 6656 bytes, Besides, we have performed the experiments to see which NIC is more stable between CF and PCMCIA type in such a wireless LAN environment, The results of such experiments show that the NIC with PCMClA type is better than that with CF type from the points of both efficiency and stability. The performance of a notebook computer with the attachment of a wireless NIC that is used as a VMS client is almost constant by varying its packet size when transferring voice data. However, with PDA client, in the case of receiving packets from the VMS server, the performance is the best when the pecket size is 6656 bytes, In addition, in the case of sending packets from PDA client to the VMS server, the performance is the best when the packet size is 4096 bytes. Even with the same pecket size, the time of receiving packets from the VMS server to PDA is longer than the time of sending packets from PDA to the VMS Server, Thus, we conclude that when PDA is used as a client by applying different pecket size when sending and receiving packets should be achieved a better performance over a wireless LAN environment.

• Journal of KIBIM
• /
• v.5 no.2
• /
• pp.1-11
• /
• 2015

Despite a lot of research on BIM, there is no quantitative study to measure accurately the performance of BIM coordination service. Thus, this study suggested method to measure the performace of BIM coordination services, applying queueing models in the field of management science. To analyze queuing system of BIM coordination services, a group of BIM coordinator were selected. Through focus group interviews with experts were used in the analysis to derive mean arrival rate(${\lambda}$), mean service rate(${\mu}$) of BIM coordination services. Single-server queuing model(M/M/1), multiple server queuing model(M/M/s) is utilized for the BIM coordination services performance measurement in construction phase. This study has significant quantitative performance measurement approaches that can be utilized in the decision-making for the improvement of the BIM coordination services and to support the review of the alternatives accordingly. But There is a limit but it is difficult to take into account the increase or decrease of the cost of alternatives according to the review.

• Proceedings of the Korea Contents Association Conference
• /
• 2004.11a
• /
• pp.395-401
• /
• 2004

In the current high network-centralized computing and enterprising environment, it is getting essential to transmit data reliably at very high rates. Until now previous client/server model based NFS(Network File System) or AFS(Andrew's Files System) have met the various demands but from now couldn't satisfy those of the today's scalable high-performance computing environment. Not only performance but data sharing service redundancy have risen as a serious problem. In case of NFS, the locking issue and cache cause file system to reboot and make problem when it is used simply as ip-take over for H/A service. In case of AFS, it provides file sharing redundancy but it is not possible until the storage supporting redundancy and equipments are prepared. Lustre is an open source based cluster file system developed to meet both demands. Lustre consists of three types of subsystems : MDS(Meta-Data Server) which offers the meta-data services, OST(Objec Storage Targets) which provide file I/O, and Lustre Clients which interact with OST and MDS. These subsystems with message exchanging and pursuing scalable high-performance file system service. In this paper, we compare the transmission speed of gigabytes file between Lustre and NFS on the basis of concurrent users and also present the high availability of the file system by removing more than one OST in operation.

• MALSORI
• /
• no.54
• /
• pp.27-43
• /
• 2005

Existing standard speech coders can provide speech communication of high quality while they degrade the performance of speech recognition systems that use the reconstructed speech by the coders. The main cause of the degradation is that the spectral envelope parameters in speech coding are optimized to speech quality rather than to the performance of speech recognition. For example, mel-frequency cepstral coefficient (MFCC) is generally known to provide better speech recognition performance than linear prediction coefficient (LPC) that is a typical parameter set in speech coding. In this paper, we propose a speech coder using MFCC instead of LPC to improve the performance of a server-based speech recognition system in network environments. However, the main drawback of using MFCC is to develop the efficient MFCC quantization with a low-bit rate. First, we explore the interframe correlation of MFCCs, which results in the predictive quantization of MFCC. Second, a safety-net scheme is proposed to make the MFCC-based speech coder robust to channel error. As a result, we propose a 8.7 kbps MFCC-based CELP coder. It is shown from a PESQ test that the proposed speech coder has a comparable speech quality to 8 kbps G.729 while it is shown that the performance of speech recognition using the proposed speech coder is better than that using G.729.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.10
• /
• pp.734-745
• /
• 2006

This paper presents a PC cluster-based distributed VOD server that minimizes the load of an interconnection network by adopting the VIA communication protocol and the interval cache algorithm. Video data is distributed to the disks of the distributed VOD server and each server node receives the data through the interconnection network and sends it to clients. The load of the interconnection network increases because of the large amount of video data transferred. This paper developed a distributed VOD file system, which is based on VIA, to minimize cost using interconnection network when accessing remote disks. VIA is a user-level communication protocol removing the overhead of TCP/IP. This papers also improved the performance of the interconnection network by expanding the maximum transfer size of VIA. In addition, the interval cache reduces traffic on the interconnection network by caching, in main memory, the video data transferred from disks of remote server nodes. Experiments using the distributed VOD server of this paper showed a maximum performance improvement of 21.3% compared with a distributed VOD server without VIA and the interval cache, when used with a four-node PC cluster.