• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.1
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• pp.1-10
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• 1982

Diffusion processes in tidal swinging coastal waters are studied by releasing one hundred liters of Rhodamine B four times. Dye patches were formed from instantaneous point sources. The patches were sampled with a pump on a tracking boat, and samples were analyzed with fluorospectro-photometer. The patterns of patches were reconstructed and their characteristics were analyzed in terms of variance of concentration, area estimation, and decrease rate of peak concentration. In all of the four experiments, the dye patches were mos시 elongated to the direction of current axis. the elongation rate was 0.34 on the average. Apparent diffusivities were 620 to 3,000 cm super(2) /sec during initial period of 90 minutes. The variance increased by exp(0.047t) on the average, and peak concentration deceased by exp(-0.044t) on the average.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.685-691
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• 2020

In this study, an algorithm that recognizes numbers from 0 to 9 was developed using the data obtained after tracking hand movements using the echo signal of a millimeter-wave radar sensor at 77 GHz. The echo signals obtained from the radar sensor by detecting the motion of a hand gesture revealed a cluster of irregular dots due to the difference in scattering cross-sectional area. A valid center point was obtained from them by applying a K-Means algorithm using 3D coordinate values. In addition, the obtained center points were connected to produce a numeric image. The recognition rate was compared by inputting the obtained image and an image similar to human handwriting by applying the smoothing technique to a CNN (Convolutional Neural Network) model trained with MNIST (Modified National Institute of Standards and Technology database). The experiment was conducted in two ways. First, in the recognition experiments using images with and without smoothing, average recognition rates of 77.0% and 81.0% were obtained, respectively. In the experiment of the CNN model with augmentation of learning data, a recognition rate of 97.5% and 99.0% on average was obtained in the recognition experiment using the image with and without smoothing technique, respectively. This study can be applied to various non-contact recognition technologies using radar sensors.

• The Journal of the Korea Contents Association
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• v.18 no.4
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• pp.416-427
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• 2018

As the loan size of real estate PF is huge, its market ripple effect gets bigger when overdue occurs. Accordingly, the management of the delinquency rate and macroeconomic analysis are required. As the preceding research mainly proceeded with microeconomic analysis through the real estate PF data of individual banks to evaluate importance of list or analyzed core factors for delinquency, it lacked research on comprehensive real estate PF size. In order to overcome the limitations of such data, this research studied real estate PF delinquency rate of the entire market and effect relationship by the size. The research utilized the size of real estate PF loans, money supply, interest rate, consumer price index(CPI), and GDP data. Also, it applied the first model of VECM as linear relationship between at least two or more variables, following the result of co-integration test. As a result of Granger-causality test, the real estate PF loans delinquency rate is influenced by their loan size, and as a result of impulse response analysis, the interest rate is shown to be affecting delinquency rate the most. Interest rate could risesomeday and aggravate the delinquency rate of real estate PF. Also, risk exposure could be serious as the loan size increases.Therefore, the management of real estate PF delinquency rate requires continuous monitoring, tracking and observing issued loans from a macro point of view. The plans to prevent delinquency will be necessary.

• Journal of the Korea Computer Industry Society
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• v.3 no.9
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• pp.1145-1156
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• 2002

A method to measure the speed and distance of moving object is proposed using the stereo vision system. One of the most important factors for measuring the speed and distance of moving object is the accuracy of object tracking. Accordingly, the background image algorithm is adopted to track the rapidly moving object and the local opening operator algorithm is used to remove the shadow and noise of object. The extraction efficiency of moving object is improved by using the adaptive threshold algorithm independent to variation of brightness. Since the left and right central points are compensated, the more exact speed and distance of object can be measured. Using the background image algorithm and local opening operator algorithm, the computational processes are reduced and it is possible to achieve the real-time processing of the speed and distance of moving object. The simulation results show that background image algorithm can track the moving object more rapidly than any other algorithm. The application of adaptive threshold algorithm improved the extraction efficiency of the target by reducing the candidate areas. Since the central point of the target is compensated by using the binocular parallax, the error of measurement for the speed and distance of moving object is reduced. The error rate of measurement for the distance from the stereo camera to moving object and for the speed of moving object are 2.68% and 3.32%, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.9-16
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• 2016

Wireless sensor networks (WSN) are composed of sensor nodes and a base station. The sensor nodes deploy a non-accessible area, receive critical information, and transmit it to the base station. The information received is applied to real-time monitoring, distribution, medical service, etc.. Recently, the WSN was extended to mobile wireless sensor networks (MWSN). The MWSN has been applied to wild animal tracking, marine ecology, etc.. The important issues are mobility and energy consumption in MWSN. Because of the limited energy of the sensor nodes, the energy consumption for data transmission affects the lifetime of the network. Therefore, efficient data transmission from the sensor nodes to the base station is necessary for sensing data. This paper, proposes an energy consumption model using two-tier clustering in mobile sensor networks (TTCM). This method divides the entire network into two layers. The mobility problem was considered, whole energy consumption was decreased and clustering methods of recent researches were analyzed for the proposed energy consumption model. Through analysis and simulation, the proposed TTCM was found to be better than the previous clustering method in mobile sensor networks at point of the network energy efficiency.

• International Journal of Highway Engineering
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• v.9 no.2 s.32
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• pp.51-62
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• 2007

Recently, the pavement distresses in the bridge deck have seriously affected the durability of bridge deck and driver's safety. The existing asphalt materials have the limitations in reducing the pavement distresses of brides deck. To protect the bridge deck and withstand the high deflection, it is necessary to develop the asphalt materials with good fatigue resistance for bridge deck pavement. The asphalt binder combined with SBS and two other admixtures has been developed for improving the resistance to fatigue cracking, productivity, and workability for bridge deck pavement. Based on the various binder test results, the developed binder is found to be PG 70-34 indicating very higher resistance against fatigue cracking. Fatigue testing, wheel tracking testing, and moisture susceptibility testing have been conducted to evaluate the performance of asphalt mixtures developed in this study. Laboratory test results show that the developed asphalt material has three times higher fatigue lives than the typical modified asphalt mixture. Full scale accelerated testing was also performed on the typical asphalt mixture and newly developed asphalt mixture to evaluate the full scale performance of asphalt mixtures. Test results indicate that the length of cracking on the new materials is only 38% of the typical material at the 250,000 load repetitions.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.143-152
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• 2014

This paper introduces Database security to prevent the rapidly increasing issue of private information leakage. The Database security examined in the paper separates into DB access control area and DB encryption area which further leads the paper to analyze the factors of the two areas and suggest necessary elements for creating stable Database security. In addition, the paper examines previous DB security programs by areas and analyzes pros and cons from the tested result. The experiment indicated that while DB access control presents less degradation and reduced the need to modify the existing DBMS since the access control operates at the end point of the network, DB encryption presented strength in protecting the data from unauthorized access. On the other hand, DB access control is less useful in preventing the attack in advance which leaves the log to enable tracking afterward while DB encryption can only be operated by limited types of Database and causes degradation due to system load and shows higher percentage of failure when creating the system. This paper examines characteristics of Database security areas in order to be used as a reference for institutions or companies seeking stable Database security.

• 한국해양학회지
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• v.30 no.5
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• pp.467-479
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• 1995

To investigate the current structures and diffusion characteristics in Youngil Bay, a systematic field observations of current velocity, drogue tracking, dye diffusion experiment and aerial photographing were performed. The flow patterns in the surface layer of the bay depend more strongly on the wind and ocean current than the tidal current, and the patterns in the middle are predominated by the ocean current. The residual currents in the surface generally flow toward the inner bay through the western and central areas of the bay, and then the currents go toward the ocean along the eastern shore of the bay with anti-clock-wise circulation. The residual currents in the surface of the eastern cease are not nearly influenced by the wind, and the currents always move northward to northeastward. However, the currents in the western shore depend strongly on the wind and the outflow of the Huntsman River, that is, the residual currents go northward to northeastward when the southerly to westerly winds blow or a large amount of flow from the river discharge. The residual currents in the middle layer flow toward the inner bay along the western shore of the bay, and the incomed currents go out to the ocean along the eastern shore with anticlockwise circulation. The diffusion of dye patch by the instantaneous point source shows a similar pattern to the drogue trajectory, and the apparent diffusion coefficients of the dye patch by Fick's theory is 1.14${\times}$10$^4$ cm$^2$/s. The behavior of the river discharges in flood shows a band type's effluent pattern toward the outer bay along the western coast.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.91-102
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• 2012

Generally today's culture and the arts industry has been focusing more on economic value than the arts. Therefore this paper will elucidate the meaning of the culture and the arts can be a break though which can only include commercial and economic values but transcend its values ultimately. First of all, this paper will suggest an advanced 3D stereoscopic images by analysis of examples and environments of realistic media arts. Looking into the changes of related technologies and market environments, the motion-recognition technology, as seem in SF film "Minority report", has become a feasible technology. In the past, 3D stereoscopic images were shown in the theme park theatre and exhibition halls for group viewing. but recent 3D TV and display devices have changed those environments to personal. Since domestic researches of realistic media art has been little, this paper will analyze them respecting to three broad classifications. The results are : Firstly, in CAVE method, more impact capabilities of spectators are expected that they can manipulate interactive interfaces freely and the physical movements of spectators can operate interactively. Secondly, inter-network communications and expansion of viewers' perceptions are predicted by way of HMD method, sensor suites and communication equipments. Thirdly, combinations of HMD and motion tracking utilization is foreseen. With the convergent usages of these three features, we can prospect the possibilities of interactive 4D that spectators wearing 3D stereoscopic display devices can experience and make their own 3D stereoscopic images actively at the point of their views.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.516-526
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• 2016

This paper introduces a hovering-type autonomous underwater vehicle (AUV) developed for research and its fundamental motion performance results obtained by simulation and field test. The AUV can control its motion in four degrees of freedom (DOF) by means of its horizontal and vertical thrusters, and it is designed to provide a test-bed that facilitates ease of operation and experimentation. Prior to the field tests, six DOF equations of motion are developed, and a simulation program is constructed using MATLAB and Simulink to verify the essential motion performance of the designed vehicle. Furthermore, a proportional-integral-derivative (PID) controller and fuzzy PID controller are designed, and their performances are verified through a simulation. Field tests are performed to verify the motion performance of the AUV; way-point tracking is executed by the PID and fuzzy PID controllers. The results confirmed appropriate control performance under current disturbances.