• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1955-1959
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• 2005

This paper presents a systematic analysis and a simple design of a robust adaptive control law for a class of non linear systems with modeling errors and a time-delay input. The theory for designing a robust adaptive control law based on input- output feedback linearization of non linear systems with uncertainties and a time-delay in the manipulated input by the approach of parameterized state feedback control is presented. The main advantage of this method is that the parameterized state feedback control law can effectively suppress the effect of the most parts of nonlinearities, including system uncertainties and time-delay input in the pp-coupling perturbation form and the relative order of non linear systems is not limited.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.6
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• pp.629-639
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• 1992

This paper examines the security vulnerability, demanded service, layering consideration for local area networks(LANs), and proposes a new key distribution system suitable to local area networks. the new key distribution system Is applicable to time quantum in encrytion key and then the time used arid the quantity of encryption message using the encryption key are limited. A system suggested in this paper can achive some higher concurrency of key and authentication of the opposite party. Even through a encryption key expose by reason of wiretapping of a frame unit, It has achived some more security and safety, because the contens of all traffic messages are not known.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.430-433
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• 2002

Fieldbus traffic consists of periodic, time-critical and time-available data. A bandwidth allocation scheme allocates periodic, time-critical and time-available data traffic to the bandwidth-limited network resource. This paper presents an implementation method of the bandwidth allocation scheme in the user layer of Foundation fieldbus. In this study, an experimental model of a Foundation Fieldbus network system is developed. Using the experimental model, validity of the bandwidth allocation scheme is examined. The results obtained from the experimental model show that the proposed scheme restricts the delay of both periodic and time-critical data to a pre-specified bound. The bandwidth allocation scheme also fully utilized the bandwidth resource of the network system.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.55-58
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• 1989

The methods of recording transient phenomena with picosecond or better resolution fall into two basic categories: those in which the detector itself prossesses adequate time resolution for the task at hand, and those in which the response of the system is sampled by examining the characteristics of a second pulse ("the probe") delayed in time from the initiating pulse ("the pump") as a function of time delay between pump and probe cases. In this case the time resolution is only limited by the pump-and probe-pulse durations. As an application of this time-resolved spectroscopic technique, the ultrafast orientational relaxation phenomena of the dye molecules are currently under investigation in our laboratory. In this presentation the status of our experiment is summarized.iment is summarized.

• Journal of Information Processing Systems
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• v.17 no.2
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• pp.227-241
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• 2021

Object detection techniques based on deep learning such as YOLO have high detection performance and precision in a single channel video stream. In order to expand to multiple channel object detection in real-time, however, high-performance hardware is required. In this paper, we propose a novel back-end server framework, a real-time AI vision platform (RAVIP), which can extend the object detection function from single channel to simultaneous multi-channels, which can work well even in low-end server hardware. RAVIP assembles appropriate component modules from the RODEM (real-time object detection module) Base to create per-channel instances for each channel, enabling efficient parallelization of object detection instances on limited hardware resources through continuous monitoring with respect to resource utilization. Through practical experiments, RAVIP shows that it is possible to optimize CPU, GPU, and memory utilization while performing object detection service in a multi-channel situation. In addition, it has been proven that RAVIP can provide object detection services with 25 FPS for all 16 channels at the same time.

• Journal of Korea Multimedia Society
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• v.24 no.3
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• pp.468-480
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• 2021

Realistic real-time rain streaks rendering has been treated as a very difficult problem because of various natural phenomena. Also, in creating and managing a large number of particles, a large amount of computer resources had to be used. Therefore, in this paper, we propose a more efficient real-time rain streaks rendering algorithm by generating view-dependent rain particles and expressing a large amount of rain even with a small number. By creating a 'rain space' dependent on the field of view of the camera moving in real time, particles are rendered only in that space. Accordingly, even if a small number of particles are rendered, since the rendering is performed in a limited space, an effect of rendering a very large amount of particles can be obtained. This enables very efficient real-time rendering of rain streaks.

• The Journal of Information Systems
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• v.18 no.3
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• pp.155-181
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• 2009

Modern persons should do many activities during limited time. In such situation, people feel time pressure because they think that time is short. Time pressure affects negatively several factors such as satisfaction and intention to use through perceived time cost. Ubiquity, an mobile service's characteristic in which users can use desired information or services in anywhere and anytime, would let users feel free from time pressure. This study examines the relationship between perceived time and intention to use and the moderating effect of ubiquity. We performed a survey for users of DMB service, a representative mobile service. Using Partial Least Square, we tested hypotheses. The results suggest that time pressure influences positively perceived time cost and that perceived time cost affects negatively satisfaction but not enjoyment. And the results show that there are the significant positive relationships between enjoyment and intention to use and between satisfaction and intention to use. Finally, the moderating effects of ubiquity on the relationships between perceived time cost and enjoyment and between perceived time cost and satisfaction was found to be positive and significant. We suggests implications basing on the results.

• Spatial Information Research
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• v.20 no.3
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• pp.83-93
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• 2012

Recent environmental concerns have made interest in environment-friendly transportation means such as walking, biking, and public transportation. However, since it is difficult to move long distance by walking or biking, their scope of application is rather limited. On the other hand, public transportation can solve traffic congestion, a recent social issue, though its usability may depend on its time schedule. Currently available information services on public transportation in the Web do not reflect well such traits of the public transportation; thus, in some cases, they may provide wrong information to end users. To solve such problems and provide information based on timetable of public transportations, this paper proposes a STP(Space Time Point) data model. Unlike existing space-time data models, this model recognizes the bottommost element of an object as a point and structures these points in hierarchical way to define an object. In particular, It can make it possible to implement a variety of dynamic spatial objects changing object information according to time. An objective of this study is to design a STP model for bus and subway based on timetables of public transportation in Daejeon area and builds a system to provide path navigation. With the designed navigation function, a path from the Daejeon National Cemetery to Hannam University was searched by time slot. The result showed that the system provided different paths by time, as the system guided different paths when bus operation was limited in midnight. As existing data model could not provide such results, it is confirmed that the system can provide path navigation based on real-time traffic information. It is expected that based on such functionality, it is possible to provide additional functionalities by applying diverse data models such as real-time transport information or traffic history information.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.8
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• pp.868-872
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• 2010

Many embedded Java systems are equipped with limited memory, which can constrain the code cache size provided for Java just-in-time compilation, affecting the Java performance. This paper proposes expanding the limited code cache when it is full, by saving the machine code for some methods in the code cache into the file system of the permanent storage and reloading it to the code cache when they are re-invoked later. This is applying the client ahead-of-time compilation during the execution time for the purpose of enlarging the code cache. Our experimental results indicate that the proposed execution method can improve the performance by as much as 1.6 times compared to the conventional method, when the code cache size is reduced by half.

• Journal of KIISE
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• v.41 no.11
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• pp.958-966
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• 2014

Wireless sensor networks offer a distributed processing environment. Many sensor nodes are deployed in fields that have limited resources such as computing power, network bandwidth, and electric power. The sensor nodes construct their own networks automatically, and the collected data are sent to the sink node. In these traditional wireless sensor networks, network congestion due to packet flooding through the networks shortens the network life time. Clustering or in-network technologies help reduce packet flooding in the networks. Many studies have been focused on saving energy in the sensor nodes because the limited available power leads to an important problem of extending the operation of sensor networks as long as possible. However, we focus on the execution time because clustering and local distributed processing already contribute to saving energy by local decision-making. In this paper, we present a cooperative processing model based on the processing timeline. Our processing model includes validation of the processing, prediction of the total execution time, and determination of the optimal number of processing nodes for distributed processing in wireless sensor networks. The experiments demonstrate the accuracy of the proposed model, and a case study shows that our model can be used for the distributed application.