• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.129-135
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• 2003

Optical fiber has many advantages, such as high reliability, long lifetime, immunity to the electromagnetic interference, high speed response and low cost. In this study, we proposed and developed an optical fiber impact and pressure sensor for prevention of accident which occurs in the automatic system or auto door. The principle of the sensor is to detect different optical intensity caused by variation of a speckle pattern due to the external perturbation. Speckle pattern appears at the end of a multimode fiber in which coherent beam propagates. The fabricated sensor in this study was tested. As a result of experiments, amplitude of the output signal isn't linear, but it has sufficient sensitivity for a sensor. Moreover, we can control sensitivity of the sensor by an amplifier at receiver. It has several advantages which are ability of detection at all point on the multimode fiber, large sensitive area, and many application areas for a sensing impact and pressure.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.1
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• pp.86-90
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• 2008

Ubiquitous Smart pace connects many kinds of smart object to satisfy user's demands. Thus, not only excessive loads but also resource collisions occur among service objects while configurating services to fulfill the user's request. After all, as malfunction occurs between service objects, it offers wrong service to user or does not respond to service request. To solve these problems, Ubiquitous Smart Space is observed by monitoring system of function, performance, and status of objects. Therefore, optimized function, performance and duality of service of smart space service for user should be improved by recording log and analyzing recorded the log. In this paper, we suggest a novel monitoring system to optimize performance according to pattern of diverse services and execute self-recovery on system down and malfunction.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.229-237
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• 2007

In this study, an artificial neural network (ANN)-based damage detection algorithm using acceleration signals is developed for real-time alarming locations of damage in beam-type structures. A new ANN-algorithm using output-only acceleration responses is designed tot damage detection in real time. The cross-covariance of two acceleration-signals measured at two different locations is selected as the feature representing the structural condition. Neural networks are trained lot potential loading Patterns and damage scenarios of the target structure for which its actual loadings are unknown. The feasibility and practicality of the proposed method are evaluated from laboratory-model tests on free-free beams for which accelerations were measured before and after several damage cases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.11
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• pp.1051-1061
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• 2004

In this Paper, a new antenna(VHMDA) characteristics of half-circular/elliptical disc-loaded planar antennas with horizontally top-loaded small disc is studied by simulation and measurements with additional resonant structure. The transfer function characteristics of Gaussian pulse from the designed UWB transmitter antenna has been investigated. The radiation pattern of the proposed antenna in azimuth is nearly omni-directional response, which is usulally required in conventional monopole antenna. In addition to that, the simulation and measured results show that the return loss characteristics of VHDMA covers considerably large bandwidth with small area. From the measured results of the circular and half-circular disc-loaded monopole antennas with small disc mounted on the top, it is found that the half disc-loaded monopole antenna with additional structure can be comparable to the circular disc-loaded monopole antenna in respect o( size and electrical performances. Surface wave and dielectric losses often caused by the printed antenna using high dielectric constant does not occur in metallic planar antenna with good impedance matching and without lossy matching unit. This structure implies that the performance of return loss is directly related with the radiation efficiency.

• The KIPS Transactions:PartB
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• v.9B no.3
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• pp.303-310
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• 2002

In this paper, we propose a proxy caching scheme that stores a portion of a continuous media object or an entire object on the Internet. The proxy stores the initial fraction of a continuous media object and determines the optimal size of the initial fraction of the continuous media object to be cached based on the object popularity. Under the proposed scheme, the initial latency of most clients and the data transferred from a remote server can be reduced and limited cache storage space can be utilized efficiently. Considering the characteristics of continuous media, we also propose the novel popularity for the continuous media objects based on the amount of the data of each object played by the clients. Finally, we have performed trace-driven simulations to evaluate our caching scheme and the popularity for the continuous media objects. Through these simulations, we have verified that our caching scheme, PPC outperforms other well-known caching schemes in terms of BHR, DSR and replacement and that popularity for the continuous media objects based on the amount of the playback data can enhance the performance of caching scheme.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.1
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• pp.52-62
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• 2003

In this paper, photonic bandgap(PBG) bandstop filters which are composed of periodically etched circles in the ground plane show good microwave characteristics with the harmonic suppression on stopband. The PBG structures were analyzed using a finite-difference time-domain(FDTD) simulation and experimental measurement. The FDTD technique is used because it can simulate arbitrary 3-D structures and provide broadband frequency response. The analysis results are presented it is the same that only one row of etched circles and 2-dimension three rows of etched circles. And we show the PBG resonator characteristics between etched circles using field pattern and frequency characteristics as functions of etched circle number n, etched circle radius r and period a.

• Journal of KIISE:Software and Applications
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• v.29 no.12
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• pp.957-965
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• 2002

Garbage collection in the CLDC typically employs a stop-the-world GC algorithm which is performing a complete garbage collection when needed. This technique is unsuitable for the interactive Java embedded system because this can lead to long and unpredictable delays. In this paper, We present a garbage collection algorithm which reduces the average delay time and supports the interactive environment. Our garbage collector is composed of the allocator and the collector. The allocator determines the allocation position of free-list according to object size, and the collector uses an incremental mark-sweep algorithm. The garbage collector is called periodically by the thread scheduling policy and the allocator allocates the objects of marked state during collection cycle. Also, we introduce a color toggle mechanism that changes the meaning of the bit patterns at the end of the collection cycle. We compared the performance of our implementation with stop-the-world mark-sweep GC. The experimental results show that our algorithm reduces the average delay time and that it provides uniformly low response times.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.39-47
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• 2020

The fire protection system for high-rise buildings is currently confined to the preparation of sprinklers, emergency stairs, and exit and monitoring systems. On the other hand, an integrated system, including the model with scenario-based actions, is required for effective fire protection. An integrated fire protection system is needed to operate and manage the total cycle of the fire protection. In this study, an integrated fire protection system, which included sensing and consequent processes related to fire emergencies, was designed and implemented. The designed scheme can gather and analyze the data of the production, operation, and consumption patterns as it integrates fire protection systems for fire fighters and evacuating people. The integrated fire protection technology and system, which has target performance with satisfied 1/2 sec transaction response time and 1.2 transactions per second, is expected to contribute to market creation in converged technology-based fire protection fields.

• Journal of KIISE:Databases
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• v.37 no.6
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• pp.300-307
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• 2010

According to growth of web, data processing technology is developing. In the Web of next generation, high-speed or high-volume data processing technologies for various wire-wireless users, USN and RFID are developing too. In this paper, we propose a high-volume data processing technology using Complex Event Processing(CEP) engine. CEP is the technology to process complex events. CEP Engine is the following characteristics. First it collects a high-volume event(data). Secondly it analyses events. Finally it lets event connect to new actions. In other words, CEP engine collects, analyses, filters high-volume events. Also it extracts events using pattern-matching for registered events and new events. As the results extracted. We use it by an input event of other work, real-time response for demanded event and can trigger to database for only valid data.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.258-262
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• 2009

The perception type of this study were divided into three types in all through Q-methodology. Above all, this study is to investigate two points us. Points of this study ; First, how the type of the perception is divided on the subjectivity about Media Fortune-contents in Digital Age? Second, what is a trait of character in same or different quality within these types? The result reveal five type that divided '1 : Scientific Appeal Type ; N=10', '2 : Value-depended Type ; N=7', '3 : Positive Preference Type ; N=3'. It found that is very different type all over.