• Journal of Korea Multimedia Society
• /
• v.20 no.2
• /
• pp.363-370
• /
• 2017

Data assimilation is an initializing method for air quality forecasting such as PM10. It is very important to enhance the forecasting accuracy. Optimal interpolation is one of the data assimilation techniques. It is very effective and widely used in air quality forecasting fields. The technique, however, requires too much memory space and long execution time. It makes the PM10 air quality forecasting difficult in real time. We propose a fast optimal interpolation data assimilation method for PM10 air quality forecasting using a new kernel tridiagonal sparse matrix and CUDA massively parallel processing architecture. Experimental results show the proposed method is 5~56 times faster than conventional ones.

• Communications for Statistical Applications and Methods
• /
• v.25 no.4
• /
• pp.355-371
• /
• 2018

The two parameter negative exponential distribution has many practical applications in queuing theory such as the service times of agents in system, the time it takes before your next telephone call, the time until a radioactive practical decays, the distance between mutations on a DNA strand, and the extreme values of annual snowfall or rainfall; consequently, has many applications in reliability systems. This paper considers an estimation problem of stress-strength model with two parameter negative parameter exponential distribution. We introduce a maximum penalized likelihood method, Bayes estimator using Lindley approximation to estimate stress-strength model and compare the proposed estimators with regular maximum likelihood estimator for complete data. We also introduce a maximum penalized likelihood method, Bayes estimator using a Markov chain Mote Carlo technique for incomplete data. A Monte Carlo simulation study is performed to compare stress-strength model estimates. Real data is used as a practical application of the proposed model.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37A no.12
• /
• pp.1023-1030
• /
• 2012

The diversity techniques can benefit underwater acoustic communications when the distance between sensors is sufficiently apart, and this leads to the increases in the physical size of the communication system: thus it is very hard to practically use such systems in real-environments. Therefore, in this paper, we have collected data from real underwater cannel environments in order to analyze the usability of diversity combined with beamforming techniques. And we have estimated the fading characteristics from the measurement data, and analyzed the correlation coefficients using the estimated fading characteristics. After analyzing the estimated fading characteristics from the measurements data, we found out that by applying diversity techniques on the output signals from beamformers that perform beamforming from different multipath directions, we can reduce the distance between sensors and at the same time benefit from the diversity gain.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.7
• /
• pp.1304-1320
• /
• 1994

There are two computation techniques in real time systems : precise and imprecise computation. The imprecise computation technique is a means to provide scheduling flexibility in real time systems. The studies on imprecise scheduling using queueing theoretical formulation up to data are to explicitly quantify the costs and benifits in trade-off between the average result quality and the average waiting time of tasks. This paper uses two imprecise scheduling schemes and solves the imprecision probability, the probability of any task being imprecise under two imprecise scheduling schemes and analyzes the dependence of the imprecision probability on several parameters os the monotone imprecise system.

• The Journal of Korean Association of Computer Education
• /
• v.14 no.5
• /
• pp.71-79
• /
• 2011

We designed and implemented a cooperative learning system using social network service which can be utilized on a smart phone for users to read each other's posting once they upload posting and to give feedback concerning the posting in real time without the need for accessing a relevant website, through the installation of a necessary application which makes it possible for learners to interact at any time in any place on a smart phone. The developed program is used as an intermediate tool for real-time communications so as to aid in solving the task of learners, and it was made to boost academic achievement as well as interest in learning through real-time interactions and feedback. Furthermore, the program was designed in such a way that an instructor actually helps learners by closely identifying their levels based on accumulated data.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.12B
• /
• pp.1063-1069
• /
• 2004

There are some problems with the methods of paging and routing cache(PRC) and quasi soft handoff that are proposed to improve the performance for the transmission of real time data. This paper proposed a reasonable solution of these problems by proposing a new method using a combined cache(CC) and applying a different handoff procedure according to each type of data. The combined cache dose not maintain the handoff state but the idlle/active state. The simulation results in a better performance than the above methods in terms of the control packet traffic load, initial recevied data packet traffic load and arrival tune of real time packet at the epoch of handoff.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.8B
• /
• pp.707-715
• /
• 2006

One of the most promising services on the wireless network is multimedia data service. With recently emerged wireless communication technologies which conventionally were devoted to mobile phone services, pre-encoded contents as well as live video data can be transmitted via the same network. As there is enough room in the improvement of data transmission bandwidth in wireless network, video data service is likely to be more demanding. In this paper, real time MPEG-4 video encoder is described as apart of a whole system for live video services over wireless networks. As there are minimal assumptions on the underlying networks, presented system and service can be easily supported by different network system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.2C
• /
• pp.208-218
• /
• 2006

In this paper, we introduce the creation methods of attack detection model using data mining technologies that can classify the latest attack types, and can detect the modification of existing attacks as well as the novel attacks. Also, we evaluate comparatively these attack detection models in the view of detection accuracy and detection time. As the important factors for creating detection models, there are data, attribute, and detection algorithm. Thus, we used NetFlow data gathered at the real network, and KDD Cup 1999 data for the experiment in large quantities. And for attribute selection, we used a heuristic method and a theoretical method using decision tree algorithm. We evaluate comparatively detection models using a single supervised/unsupervised data mining approach and a combined supervised data mining approach. As a result, although a combined supervised data mining approach required more modeling time, it had better detection rate. All models using data mining techniques could detect the attacks within 1 second, thus these approaches could prove the real-time detection. Also, our experimental results for anomaly detection showed that our approaches provided the detection possibility for novel attack, and especially SOM model provided the additional information about existing attack that is similar to novel attack.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.7
• /
• pp.9-18
• /
• 1997

In this paper, we implemented the communication module in the Telephone Network Access Subsystem(TNAS) of the Advanced Communications Processing System(ACPS). We defined some kinds of communication tasks and related resources like several queues which are executed in real-time operating system, and implemented the procedures for processing the user information. Through traffic modeling and simulation, the performance of the Service Processing board Assembly(SPA) is evaluated in the aspets of system utilization and buffer size. The ACPS should accommodate various public networks such as public switch telephone network, packet switchen data network, frame realy netork, and ATM network. The communications module proposed in this paper could be used inthe interface beween the SPA and the High Speed Network Adaptor of other network interface subsystems.

• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.47-50
• /
• 2004

In this paper, we implement an Elliptic Curve Cryptosystem(ECC) processor for DTCP. Because DTCP(Digital Transmission Content Protection) uses GF(p), where p is a 160-bit prime integer, we design a scalar multiplier based on GF(p). The scalar multiplier consists of a modular multiplier and an adder. The multiplier uses montgomery algorithm which is implemented with CSA(Carry-save Adder) and CLA(Carry-lookahead Adder). Our new scalar multiplier has been synthesized using Samsung 0.18 um CMOS technology and the maximum operation frequency is estimated 98 MHz, with the size about 65,000 gates. The resulting performance is 29.6 kbps, that is, it takes 5.4 msec to process a 160-bit data frame. We assure that this performance is enough to be used for digital signature, encryption/decryption, and key exchanges in real time environments.