• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.2
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• pp.89-94
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• 2014

Spatial variations of a seismic wave are mainly wave passage and wave scattering. Wave passage effect is produced by changed characteristics of exciting seismic input motions applied to the bedrock. Modified input motions travel horizontally with time differences determined by apparent shear wave velocity of the bedrock. In this study, wave passage effect on the seismic response of a structure-soil system is investigated by modifying the finite element software of P3DASS (Pseudo 3-Dimensional Dynamic Analysis of a Structure-soil System) to apply inconsistent (time-delayed) seismic input motions along the soft soil-bedrock interface. Study results show that foundation size affected on the seismic response of a structure excited with inconsistent input motions in the lower period range below 0.5 seconds, and seismic responses of a structure were decreased considerably in the lower period range around 0.05 seconds due to the wave passage. Also, shear wave velocity of the bedrock affected on the seismic response of a structure in the lower period range below 0.3 seconds, with significant reduction of the seismic response for smaller shear wave velocity of the bedrock reaching approximately 20% for an apparent shear wave velocity of 1000m/s at a period of 0.05 seconds. Finally, it is concluded that wave passage effect reduces the seismic response of a structure in the lower period range when the bedrock under a soft soil is soft or the bedrock is located very deeply, and wave passage is beneficial for the seismic design of a short period structure like a nuclear container building or a stiff low-rise building.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.3
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• pp.88-100
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• 2009

An inundation analysis was performed on Hwapocheon, one of the tributaries of Nakdong River, which was inundated by heavy rain in August, 2002 with overtopping and levee break. The results of the developed model, 2D diffusion wave inundation analysis model, was compared with inundation trace map as well as inundation depth in terms of time and maximum inundated area calculated from FLUMEN model for the assessment of model applicability. The results from the developed model showed high fitness of 88.61% in comparison with observed data. Also maximum inundated area and spatial distribution of inundation zone were also found to be consistent with the results of FLUMEN model. Therefore, inundation zone and maximum inundation area calculated over a period of time by adopting 2D diffusion wave inundation analysis model can be used as a database for identifying high risk areas of inundation and establishing flood damage reduction measures.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.100-106
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• 2015

In this paper, we propose a fast algorithm for low-power image enhancement method for mobile LCD. In the proposed fast algorithm, the spatial resolution of the input image is significantly reduced, and the image characteristics are analyzed on the reduced resolution image to find a dimming rate adaptive to the image content, thereby saving power. The proposed fast adaptive dimming and image enhancement algorithm is implemented as an application that runs on an Android device. Image quality evaluation and running time analysis experiments on the device indicate that the proposed fast algorithm jointly minimizes the quality degradation and power consumption, reducing the required computation load by over 95%.

• The Journal of the Korea Contents Association
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• v.18 no.12
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• pp.35-45
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• 2018

Motion Estimation(ME) has been developed to reduce the redundant data in digital video signal. ME is an important part of video encoding system, However, it requires huge computational complexity of the encoder part, and fast motion search methods have been proposed to reduce huge complexity. Multi- view video is obtained by capturing on a three-dimensional scene with many cameras at different positions and its complexity increases in proportion to the number of cameras. In this paper, we proposed an efficient motion method which chooses a search pattern adaptively by using the temporal-spatial correlation of the block and the characteristics of the block. Experiment results show that the computational complexity reduction of the proposed method over TZ search method and FS method can be up to 70~75% and 99% respectively while keeping similar image quality and bit rates.

• Journal of Korean Society of Rural Planning
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• v.25 no.3
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• pp.37-44
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• 2019

The value of Jeju Batdam has been reexamined as it is listed as a nationally important agricultural heritage and globally important agricultural heritage systems. However, it is already exposed to threats such as reduction of agricultural population and cultivation area. Despite efforts like the agricultural heritage system to preserve traditional agriculture, there is few basic investigation into the current status of Jeju Batdam. The purpose of this study is to estimate the length of Jeju Batdam. We used the continuous cadastral map of Jeju area to extract the boundaries of the field lot. In the cadastral map, the farmland was selected by selecting dry fields, paddy fields and orchards. 300 sample site were selected from the extracted farmland, and the boundaries between the Internet map and the parcels were superimposed and the differences were confirmed on the drawing. After that, field survey was conducted to confirm the boundary of the parcels and the existence of actual Batdam. It is estimated that the length estimated from this study is at least 23,983km and maximum 142,353km, which is at least 1,830km longer than 22,108km announced in 2007. Since Jeju Batdam is based on land parcel boundary, it is an objective and efficient method to utilize intellectual information. In addition, because it is subordinate to farmland, new information can be extracted reflecting the change of land use and make the spatial database based on the cadastral maps.

• Convergence Security Journal
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• v.18 no.2
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• pp.33-40
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• 2018

ICT technology has been applied to various educational fields, but applying to educational test field is limited. Computer-based test (CBT) can overcome temporal and spatial constraints of conventional paper-based test, but is vulnerable to fraud by test parties. In this paper, we propose real-time monitoring and process management methods to enhance the security of CBT. In the proposed methods, the test screens of students are periodically captured and transferred to the professor screen to enable real-time monitoring, and the possible processes used for cheating can be blocked before testing. In order to monitor the screen of many students in real time, effective compression of the captured original image is important. We applied three-step compression methods: initial image compression, resolution reduction, and re-compression. Through this, the original image of about 6MB was converted into the storage image of about 3.8KB. We use the process extraction and management functions of Windows API to block the processes that may be used for cheating. The CBT system of this paper with the new security enhancement methods shows the superiority through comparison of the security related functions with the existing CBT systems.

• Convergence Security Journal
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• v.18 no.4
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• pp.62-71
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• 2018

The rapid growth of virtual reality technology in the era of the 4th Industrial Revolution has accelerated scientification of combat training systems in addition to ICT(information and communications technology) in military field. Recently, research and development of simulators based on virtual reality have been actively conducted in order to solve sensitive issues such as increase of civil complaints due to the noise of a shooting range, prevention of shooting accident, and reduction of training cost. In this paper, we propose two key solutions: spatial synchronization method and modified point mass trajectory model with small angle approximation to overcome technical limitations of a current training simulator. A trainee who wears a haptic vest in a mixed reality environment built in MARS(medium-range assault rifle shooting simulator) is able to conduct not only precision shooting but also two-way engagement with virtual opponents. It is possible for trainee to receive more reliable evaluations in the MARS than an existing rifle simulator based on laser.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.6
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• pp.1-13
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• 2018

Mapping radiation heat flux of urban area is essential for urban design and landscape planning. Because controlling urban geometry and generating green space are important urban design strategies for reducing urban heat, urban planner and designer need to recognize the micro urban heat distribution for adequate urban planning. This study suggests a new methodology for mapping urban radiation heat flux in a micro scale considering buildings and trees' shade. For doing that, firstly, we calculate net radiation for each urban surfaces (building, road (not shaded, building shaded, tree shaded), ground (not shaded, building shaded, tree shaded), tree (not shaded, building shaded)). Then, by multiplying the area ratio of surfaces to the net radiation, we can obtain the radiation heat flux in micro-scale. The estimated net radiation results were found to be robust with a $R^2$ of 90%, which indicates a strong explanatory power of the model. The radiation heat flux map for 12h $17^{th}$ August explains that areas under the building and tree have lower net radiation heat flux, indicating that shading is a good strategy for reducing incident radiation. This method can be used for developing thermal friendly urban plan.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.1
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• pp.17-25
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• 2019

An intake of Aircraft becomes S-shaped geometry due to spatial limitation or procuring survivability. But curvature of the S-shaped geometry makes secondary flow or flow separation which is the cause of non-uniform pressure distribution. In this study, boundary layer suction is applied to RAE M 2129 S-Duct by attaching sub duct. Design variable is suction location and angle. A mass flow rate drawn out by suction at the sub duct outlet is constant over every model. A grid dependency test was conducted to verify validity of computation. The comparison among the CFD (Computation Fluid Dynamics), ARA experimental result, and ARA computation result of non-dimensional pressure distribution on the Port side and Starboard Side confirmed the validity of CFD. In this study, Distortion Coefficient was used for evaluating aerodynamic performance of S-Duct. The analysis, which was about flow separation, vortex, mass flow rate distribution, and pressure distribution were also investigated. Maximum 26.14% reduction in Distortion Coefficient was verified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.10
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• pp.1310-1316
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• 2021

Recently, with the development of artificial intelligence and IoT technology, the importance of video processing such as object tracking, medical imaging, and object recognition is increasing. In particular, the noise reduction technology used in the preprocessing process demands the ability to effectively remove noise and maintain detailed features as the importance of system images increases. In this paper, we provide a modified weight filter based on pixel matching in an AWGN environment. The proposed algorithm uses a pixel matching method to maintain high-frequency components in which the pixel value of the image changes significantly, detects areas with highly relevant patterns in the peripheral area, and matches pixels required for output calculation. Classify the values. The final output is obtained by calculating the weight according to the similarity and spatial distance between the matching pixels with the center pixel in order to consider the edge component in the filtering process.