• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.6
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• pp.477-483
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• 2016

Velocity profiles of laminar, transition and turbulent boundary layers were investigated by using Particle Image Velocimetry(PIV) measurements on the flat plate at Mach 2.96. The Schlieren visualization and PIV measurements are also used to confirm whether the oblique shock wave generated from the leading edge affects the flow field over the flat plate. The laminar velocity profile measured from the experiment was well matched with the compressible Blasius solution. The velocity profile of the transition boundary layer was well correlated with the theoretical turbulent velocity profile from near the wall and the transition began from Re = $1.41{\times}106$. For the turbulent boundary layer, considering compressibility effects, the Van Driest-transformed velocity satisfies the incompressible log-law. It is found that the log region is extended farther in the wall-normal direction compared to the log region in incompressible boundary layer.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.3
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• pp.101-113
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• 2011

The purpose of this study are to develop a SDSS (Spatial Decision Support System) that can incorporate diverse opinions of stakeholders related the designation of protected areas (PA), and to employ the model for the readjustment of the boundary line of the Jirisan National Park of Korea. The SDSS would lead to more rational and less controversial decision-making during the expansion or removal of PA in Korea. Research methods are as follows. Firstly, to select evaluation criteria for SDSS for PA designation by using expert interview and literature survey. Secondly, to measure their preferences on the designation of additional PA or the removal of a part of PA based on the opinions of various stakeholders such as local residents, environmental groups, or public officials. Thirdly, to produce conservation priority maps based on a multi-criteria decision making technique. The SDSS would be used to rational decision making for the expansion of PA or the release of a certain part of PA by reflecting diverse preferences on biodiversity conservation and economic interest of residents. The visualization of conservation priority maps would also increase the efficiency of such decision making processes. The evaluation criteria for the expansion of PA for biodiversity conservation includes vegetation conservation value, wildlife conservation value, and the habitats of key species. The evaluation criteria for the removal of PA includes the proximity to roads and the boundary of PA, land use types, and conservation zoning of the PA. Preference weights are based on data collected from the Jirisan National Park. Both the conservation priority and removal priority maps are based on land parcels so that property rights of all parcels would be correctly represented.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.3
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• pp.83-90
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• 2011

The purpose of this study is to develop a series of trend analysis models for industrial water consumption and to propose a blueprint for the integration of the developed models with GIS. For the consumption data acquisition, a real-time sensing technique was adopted. Data were transformed from the field equipments to the management server in every 5 minutes. The data acquired were substituted to a polynomial formula selected. As a result, a series of models were developed for the consumption of each day. A series of validation processes were applied to the developed models and the models were finalized. Then the finalized models were transformed to the average models representing a day's average consumption or an average daily consumption of each month. Demand pattern analyses were fulfilled through the visualization of the finally derived models. It has founded out that the demand patterns show great consistency and, therefore, it is concluded that high probability of demand forecasting for a day or for a season is available. Also proposed is the integration with GIS as an IT tool by which the developed forecasting models are utilized.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.157-166
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• 2009

There is a growing interest in ubiquitous-related research and applications. Among them, GPS-based LBS have been developed and used actively. Recently, with the increase of large size buildings and disastrous events, indoor spaces are getting attention and related research activities are being carried out. Core technologies regarding indoor applications may include 3D indoor data modeling and localization sensor techniques that can integrate with indoor data. However, these technologies have not been standardized and established enough to be applied to indoor implementation. Thus, in this paper, we propose a method to build a relatively simple 3D indoor data modeling technique that can be applied to indoor location based applications. The proposed model takes the form of 2D-based multi-layered structure and has capability for 2D and 3D visualization. We tested three prototype applications using the proposed model; CA(cellular automata)-based 3D evacuation simulation, network-based routing, and indoor moving objects tracking using a stereo camera.

• Spatial Information Research
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• v.14 no.2 s.37
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• pp.223-234
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• 2006

In order to examine spatio-temporal characteristics of coastal water quality, we applied GIS spatial analysis to the water quality data collected from observation points located on Korean coastal area during 1997$\sim$2004. The water quality parameters measured included: chlorophyll-a, pH, DO, COD, SS, dissolved inorganic nitrogen, dissolved inorganic phosphorous, salinity, temperature. The water quality data used in this paper was obtained only at selected sites even though they are potentially available at any location in a continuous surface. Thus, it is necessary to estimate the values at unsampled locations so as to analyze spatial distribution patterns of coastal water quality, Owing to this reason, we applied IDW(inverse distance weighted) interpolation method to water quality data and evaluated the usefulness of IDW method. After IDW interfolation method was applied, we divided the Korean coastal area into 46 sections and examined spatio-temporal patterns of each section using GIS visualization technique. As a result of evaluation, we can blow that IDW interpolation and GIS are useful for understanding spatial and temporal distribution characteristics of coastal water quality data which is collected from a wide area far many years.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.1-8
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• 2005

This paper explored the effects of separation control through the use of pulsating jet blowing on a two dimensional elliptical airfoil. To develop an active control technique of flow separation, a flow control actuator utilizing continuous/pulsed jet of pressurized air was designed and installed in a wind tunnel testing model of elliptic wing. PIV measurement and flow visualization of the wing near field were conducted to access the feasibility and effectiveness of the pulsed jet blowing on controlling the stall of the elliptical wing in subsonic flow. PIV experimental results show that separation control can provide significant reduction in turbulent flow wake and separation bubbles by jet blowing. The pulsating jet blowing is more effective on the separation control than continuous one. Increased jet frequency suppressed the turbulent separated flow wake effectively at even higher AOAs.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.143-148
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• 2016

There is increasing concern about security as a need for increased safety in the information industry society. However, it does not meet the needs for safety including CCTV. Therefore, in this paper, we link the processing technology using the image information to the IPS system consisting of GPS and Beacon. It designed a conventional RFID tag attached discomfort and image tracking system is limited to complement the disadvantages identifiable area. To this end, we designed a smart device and the Internet of Things convergence system and a research to ensure the accuracy and reliability of the IPS of the access control system. Finally, by leveraging intelligent video information using a PTZ camera, and set the entrant management policies it was carried out to control the situation and control. Also, by designing the integrated video tracking system, an authentication server, visualization systems were designed to establish an efficient technique for analyzing the IPS entrant behavior patterns.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.719-724
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• 2003

The present experimental study deals with noise reduction and improvements in cooling performance in a plasma display panel(PDP) television (TV). To reduce the noise, the effects of installation parameters are studied. The experimental parameters under investigation are the distance between the fan and the rear case of a PDP TV, position of the strut on the fan, and the fan RPM. The variance of RPM is the most significant facto., and a 250 RPM decrease from 910 RPM causes about 4㏈(A) reduction in the system noise. To increase performance, flow characteristics are investigated by using a visualization technique and measuring the volume flow rate. The visualized results show that a radial direction flow due to large system resistance is significant, and an axial velocity oscillation is observed from the measurement of the volume flow rate. To prevent both a radial direction flow and an axial velocity oscillation, sponges are inserted in the space between f3n and the rear case. Inserted sponges improve the volume flow rate of cooling fans up to 32% since they convert a radial direction flow to an axial direction flow. Also an axial velocity oscillation with large amplitude and low RPM disappears. Increasing volume flow rate causes the PDP TV to improve its cooling performance. Additionally the same volume flow rate can be obtained with a decreased fan speed due to the inserted sponge. Noise reductions of 4.2 ㏈(A) at the rear and 1.1 ㏈(A) at the front of the TV are obtained by the decreased RPM. An increase of 10% of the volume flow rate is also achieved by inserting sponges.

• Journal of the Korea Society for Simulation
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• v.16 no.3
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• pp.57-63
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• 2007

In real time rendering of fetus the empty space leaping while traversing a ray is most frequently used accelerating technique. The main idea is to skip empty voxel samples which do not contribute the result image and it speeds up the rendering time by avoiding sampling data while traversing a ray in the empty region, saving a substantial number of interpolations. Calculating the distance from the nearest object boundary for every yokel can reduce the sampling operation. Among widely-well-known distance maps, those estimates the true distance, such as euclidean distance, takes a long time to compute because of the complicated floating-point operations, and others which uses approximated distance functions, such as city-block and chessboard, provides faster computation time but sampling error may can occur. In this paper, therefore, we analyze the characteristics of several distance maps and compare the number of samples and rendering time. And we aim to suggest the most appropriate distance map for rendering of fetus in ultrasound image.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.219-224
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• 2017

These days, it is developed renewable energy-based wind power technology. Wind power generation is relatively quiet, and environmental damage is relatively low. In developed countries, a lot of wind power generation is being built. In Korea, the generation efficiency is low because there are few areas where the wind speed is maintained for four seasons. In recent years, forest damage, low noise, and environmental degradation complaints are frequent. In this paper, we performed an experiment to manage pitch control effectively by analyzing wind, direction, and temperature in real time based on FUZZY rule and cluster analysis.Using the new algorithm proposed by the simulation results, we could verify the efficiency of wind power generation pitch control for wind condition and direction condition by using the pitch control analysis technique.Furthermore, visualization representations have proven to automatically analyze early warning and efficiency of generator performance.