• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.483-488
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• 2012

With the fast growing data traffic, the performance of the convergent overlay network environment under the cognitive networking environment is crucial for the implementation of the efficient network structure. In order to achieve high capacity and reliable link quality in wireless communication of the overlay convergent networks with the cognitive networking based on the advanced capability of the mobile terminal, a Distributed Wireless Communication System (DWCS) can provide the capability of ambient-aware dual cell system's operation. This paper has considered virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. One is the Active Virtual Cell which exists for user's actual data traffic and the other is the Candidate Virtual Cell which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. The considered system constructs DVC by using cognitive ability of finding useful virtual signals. Also, for multi-user high-rate data transmission, the DWCS system exploits Space-Time Trellis Codes. The effects of changing environments on the system performance has been investigated thereafter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1834-1843
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• 2016

DVRs are the most common recording and displaying devices used for surveillance. Video compression plays a key role in DVRs for saving storage; the video compression standard, H.264/AVC, has recently become the dominant choice for DVRs. DVRs require various display modes, such as fast-forward, backward play, and pause; these are called trick modes. The implementation of precise trick mode play requires a very high decoding capability or a very intelligent scheme in order to handle the high computation complexity. The complexity is increased in many surveillance applications where more than one camera is used to monitor multiple spots or to monitor the same area using various angles. An implementation of a trick mode play and a frame buffer management scheme for the hardware-based H.264/AVC codec for multi-channel is presented in this paper. The experimental results show that exact trick mode play is possible using a standard H.264/AVC video codec with keyframe encoding feature at the expense of bitstream size increase.

• Journal of the Korean Institute of Intelligent Systems
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• v.9 no.6
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• pp.650-656
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• 1999

In this paper, we study on the convergence of the evolution strategies by introducing the Lamarckian evolution and the Baldwin effect, and propose a random local searching and a reinforcement local searching methods. In the random local searching method some neighbors generated randomly from each individual are med without any other information, but in the reinforcement local searching method the previous results of the local search are reflected on the current local search. From the viewpoint of the purpose of the local search it is suitable that we try all the neighbors of the best individual and then search the neighbors of the best one of them repeatedly. Since the reinforcement local searching method based on the Lamarckian evolution and Baldwin effect does not search neighbors randomly, but searches the neighbors in the direction of the better fitness, it has advantages of fast convergence and an improvement on the global searching capability. In other words the performance of the evolution strategies is improved by introducing the learning, reinforcement local search, into the evolution. We study on the learning effect on evolution strategies by applying the proposed method to various function optimization problems.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.619-629
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• 2002

Water in the atmosphere is circulated by reciprocal action of various factors in the climate system. Otherwise, any climate phenomenon could not occur of itself. Thus, we have tried to understand the climate change by analysis of the factors. In this study, the fuzzy theory which is useful to express inaccurate and approximate nature in the real world is used for forecasting precipitation influenced by the factors. Forecasting models used in this study are neuro-fuzzy system and a Markov chain and those are applied to precipitation forecasting of illinois. Various atmosphere circulation factors(like soil moisture and temperature) influencing the climate change are considered to forecast precipitation. As a forecasting result, it can be found that the considerations of the factors are helpful to increase the forecastibility of the models and the neuro-fuzzy system gives us relatively more accurate forecasts.

• Tunnel and Underground Space
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• v.18 no.5
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• pp.375-385
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• 2008

Hydraulic analysis in a dam that has a single outlet of water can be made through a simple comparison between the total precipitation and the volume of discharged water. In case of tailing dams this estimation could yield an error because several drainage facilities are worked independently as well as simultaneously. In this research, a capability of the drainage system in the tailing dam of the old Sangdong Mine was analysed by the means of GIS technic. As a result of this study, it was expected that in the normal working condition of the whole drainage system, the flooding of water over the dam should not occur in spite of the consecutive precipitation during one hour with an intensity of 80.31 mm/hr, a probable precipitation within 100 years. It was, however, revealed that, if the drainage system did not work completely, the water could flood over the dam when the total precipitation reached 251.1 mm.

• Journal of Korea Water Resources Association
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• v.37 no.6
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• pp.449-460
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• 2004

The purpose of this study is to test the applicability of neuro-fuzzy system for monthly dam inflow forecasts by using weather forecasting information. The neuro-fuzzy algorithm adopted in this study is the ANFIS(Adaptive neuro-fuzzy Inference System) in which neural network theory is combined with fuzzy theory. The ANFIS model can experience the difficulties in selection of a control rule by a space partition because the number of control value increases rapidly as the number of fuzzy variable increases. In an effort to overcome this drawback, this study used the subtractive clustering which is one of fuzzy clustering methods. Also, this study proposed a method for converting qualitative weather forecasting information to quantitative one. ANFIS for monthly dam inflow forecasts was tested in cases of with or without weather forecasting information. It can be seen that the model performances obtained from the use of past observed data and future weather forecasting information are much better than those from past observed data only.

• Journal of Engineering Education Research
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• v.5 no.1
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• pp.27-33
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• 2002

Recently, according to the appearance of various virtual websites using multimedia technologies, the internet applications in engineering education have drawn muchinterests. But unidirectional communication, simple text/image-based webpages and tedious learning process without motivation, etc. have made the lowering of educational efficiency in cyberspace. This paper presents a virtual laboratory system which can be creating efficiencies in the learning process. The proposed virtual laboratory system for digital logic circuits provides interactive learning environment under which the multimedia capabilities of world-wide web can be enhanced. The virtual laboratory system is implemented to describe the on-campus laboratory, the learners can obtain similar experimental data through it. The virtual laboratory system is composed of four important components : principle classroom, simulation classroom, virtual experiment classroom and management system. Learning efficiencies as well as faculty productivity are increased in this innovative teaching and learning environment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.2
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• pp.142-150
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• 1999

During the past three decades after the first attempt to use satellite imagery or derived cloud products for rainfall estimation, much is known and understood concerning the scope and difficulties of satellite rainfall monitoring. After a brief general introduction this paper reviews recent progress in this field with special reference to improvement of algorithms, inter-comparison projects, integrative use of data from different sources, increasing lengths of data records and derived products, and interpretability of rainfall results. Also the paradigm of TRMM (Tropical Rainfall Measuring Mission) which is the first space mission(1997) dedicated to measuring tropical and subtropical rainfall though microwave and visible/infrared sensors, including the first spaceborne rain radar was introduced, and the potential applicability to the field of agriculture and water resources by combining satellite imagery is described.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3B
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• pp.462-473
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• 2010

The RFID system has the security problem of location tracking and user privacy. In order to solve this problem, the cryptographic access method using hash function is difficult to in real applications. Because there is a limit of computing and storage capacity of Tag, but the safety is proved. The lightweight authentication methods like HB and LMAP guarantee the high efficiency, but the safety is not enough to use. In this paper, we use the AES for RFID Authentication, and solve the problem of using fixed key with key change step by step. The symmetric keys of the tag and server are changed by the random number generated by tag, reader and server successively. This could prevent the key exposure. As a result, the output of the tag and reader always changes. These key changes could make it possible to prevent eavesdropping, replay attack, location tracking and spoofing.

• Journal of the Korea Society of Computer and Information
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• v.4 no.4
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• pp.47-56
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• 1999

We design and implement an ORDBMS-based geographic information system for sightseeing information of Chungbuk to verify the performance and applicability of GEUS/XTM ORDBMS. We Acquire the positional coordinates of the boundaries of administrative districts , roads, and railroads, determine the various kinds of information such as the locations of sightseeing sites, lodgings, and so on, design an object-relational schema using OMT, and implement the geographic information system including a database system. Through the examination of selective accessibility on the sightseeing inform ation database by the various queries, we conclude that the ORDBMS is more applicable than other DBMSs in modeling, storing, referring, and managing of non-fixed complex data such as sightseeing information. Therefore, ORDBMSs provide efficient and extensible implementations of databases and information services from various sources for the increasing demand on geographic information service on internet.