• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5B
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• pp.317-323
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• 2005

Broadcast disks are suited for disseminating information to a large number of clients in mobile computing environments. In broadcast disks, the server continuously and repeatedly broadcasts all data items in the database to clients without specific requests. The clients monitor the broadcast channel and retrieve data items as they arrive on the broadcast channel. The broadcast channel then becomes a disk from which clients can retrieve data items. This paper proposes a Timestamp based Concurrency Control (TCC) scheme to preserve the consistency of read-only client transactions, when the values of broadcast data items are updated at the server. Previous schemes tried to reduce transaction aborts by consuming considerable amount of downlink communication from the server to clients for transferring control information. On the other hand, the TCC uses a timestamp field of each data item to describe execution order of server transactions. Clients can allow more transaction executions by checking consistency of their read-only transactions with timestamps of data items. As a result, the TCC can reduce the abort ratio of client transactions with minimal control information to be broadcast from the server.

• Spatial Information Research
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• v.13 no.4 s.35
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• pp.345-354
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• 2005

Super resolution image reconstruction method refers to image processing algorithms that produce a high resolution(HR) image from observed several low resolution(LR) images of the same scene. This method has proven to be useful in many practical cases where multiple frames of the same scene can be obtained, such as satellite imaging, video surveillance, video enhancement and restoration, digital mosaicking, and medical imaging. In this paper, we applied the super resolution reconstruction method in spatial domain to video sequences. Test images are adjacently sampled images from continuous video sequences and are overlapped at high rate. We constructed the observation model between the HR images and LR images applied with the Maximum A Posteriori(MAP) reconstruction method which is one of the major methods in the super resolution grid construction. Based on the MAP method, we reconstructed high resolution images from low resolution images and compared the results with those from other known interpolation methods.

• Journal of Radiation Protection and Research
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• v.35 no.4
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• pp.172-177
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• 2010

The radioactive effluents from pressurized heavy water reactors (PHWRs) are relatively larger than those from pressurized water reactors (PWRs). Futhermore, radioactive effluents from PHWRs are released continuously. Thus, the discharge of radioactive effluents is strictly controlled. To do this, radiation detectors are installed at stacks of reactor buildings to monitor the concentration of radioactive effluents in real-time. Derived release limits (DRLs) of annual discharge are also set up for each radionuclide and effluents are rigidly controlled not to exceed those limits. In this paper, the discharge process of radioactive effluents, the standard for establishment of DRL and its methodology, and currents status for PHWRs were reviewed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.454-460
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• 2020

In recent years, the rapid increases in video distribution and viewing over the Internet have increased the risk of personal information exposure. In this paper, a method is proposed to robustly identify areas in images where a person's privacy is compromised and simultaneously blocking the object area by blurring it while rapidly tracking it using a prediction algorithm. With this method, the target object area is accurately identified using artificial neural network-based learning. The detected object area is then tracked using a location prediction algorithm and is continuously blocked by blurring it. Experimental results show that the proposed method effectively blocks private areas in images by blurring them, while at the same time tracking the target objects about 2.5% more accurately than another existing method. The proposed blocking method is expected to be useful in many applications, such as protection of personal information, video security, object tracking, etc.

• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.510-516
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• 2011

For using Global Navigation Satellite System(GNSS) in the civil aviation, it should satisfies the Required Navigation Performances(RNPs) which are defined by International Civil Aviation Organization(ICAO). RNP defines the required accuracy, integrity, availability, continuity of each flight procedure. In order to guarantee user's integrity, user's protection level has to be overestimated. On the other hand, for improving user's availability, user's protection level has to be estimated tightly. Therefore protection level should be estimated as tight as possible while it assuring the user's integrity. This paper describes the current integrity function of Korean WAD GNSS test bed, and predicts the availability performance of Korean WAD GNSS by simulation.

• Smart Media Journal
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• v.1 no.2
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• pp.12-22
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• 2012

Today we are witnessing an increasingly widespread use of cameras in our lives for video surveillance, robot vision, and mobile phones. This has led to a renewed interest in computer vision in general and an on-going boom in human activity recognition in particular. Although not particularly fancy per se, human gait is inarguably the most common and frequent action. Early on this decade there has been a passing interest in human gait recognition, but it soon declined before we came up with a systematic analysis and understanding of walking motion. This paper presents a set of DBN-based models for the analysis of human gait in sequence of increasing complexity and modeling power. The discussion centers around HMM-based statistical methods capable of modeling the variability and incompleteness of input video signals. Finally a novel idea of extending the discrete state Markov chain with a continuous density function is proposed in order to better characterize the gait direction. The proposed modeling framework allows us to recognize pedestrian up to 91.67% and to elegantly decode out two independent gait components of direction and posture through a sequence of experiments.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.10-18
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• 2012

Automatic smoke detection systems using a surveillance camera requires a reliable smoke detection method. When an image sequence is captured from smoke spreading over in the air, not only has each smoke image frame a special texture, called static texture, but the difference between two smoke image frames also has a peculiar texture, called dynamic texture. Even though an object has a static texture similar to that of the smoke, its dynamic texture cannot be similar to that of the smoke if its movement differs from the diffraction action of the smoke. This paper presents a reliable smoke detection method using these two textures. The proposed method first detects change regions using accumulated frame difference, and then picks out smoke regions using Haralick features extracted from two textures.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.113-118
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• 2015

High-power semiconductor devices and microprocessors in factory electrical installation so sensitive to power quality measurements such as harmonic currents, voltage fluctuations, flicker, current imbalance. Therefore, the little change of power quality can influences the productivity of factory electrical machines. Troubleshooting these problems requires accurate measurements and analysis of power quality with monitoring instruments that can effectively locate issues and identify solutions. In this paper, the author presents hand-held power quality monitoring system to locate issues and identify solutions. The proposed system consists of two parts, One is to develop hand-held power meters by using NI(National Instrument) DAQ(Data Acquisition) and WLAN. Another is develop power quality monitoring MMI(Man-Machine Interface) using LabView software. To demonstrate the validity of the proposed algorithm, variable tests are carried out.

• The Transactions of the Korea Information Processing Society
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• v.1 no.4
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• pp.479-489
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• 1994

At the present time, it is an important problem that we are to select a transmission line code for the very-high speed optical transmission system which can confidentially transfer the original information signal sequence efficiently, as it is to be the large capacity and the economization for the optical digital transmission system to transfer the information signal sequence at the very-high speed. Therefore, this paper is to select first the proper transmission line codes for the high speed(more than Mb/s) optical transmission system of the proposed two-level unipolar transmission line codes up to date, and to decide a mBIZ (m Binary with One Zero insertion) code as an optimal transmission line code for the very-high speed optical transmission system, resulting from analyzing the performance at the requirements of the transmission line code, such as the maximum consecutive identical digits, the transmission delay time, the increasing rate of clock, the mark rate, the circuit complexity, the supervision of transmission line error, and power spectrum among the selected transmission line codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.47-59
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• 2014

This paper deals with a vision-based trajectory tracking control system for a quadrotor-type UAV for entertainment purpose in indoor environment. In contrast to outdoor flights that emphasize the autonomy to complete special missions such as aerial photographs and reconnaissance, indoor flights for entertainment require trajectory following and hovering skills especially in precision and stability of performance. This paper proposes a trajectory tracking control system consisting of a motion generation module, a pose estimation module, and a trajectory tracking module. The motion generation module generates a sequence of motions that are specified by 3-D locations at each sampling time. In the pose estimation module, 3-D position and orientation information of a quadrotor is estimated by recognizing a circular ring pattern installed on the vehicle. The trajectory tracking module controls the 3-D position of a quadrotor in real time using the information from the motion generation module and pose estimation module. The proposed system is tested through several experiments in view of one-point, multi-points, and trajectory tracking control.