• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.10
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• pp.1155-1162
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• 2004

This paper is the forth paper of several companion papers which compare the method of Air-Fuel ratio determination. In the previous work, various AFR calculations were performed for various fuels and the results were compared with each other. The comparison, however, were limited to numerical value and estimation of each equation or method was insufficient. In this paper, the overall estimation of the methods was attempted. Also, the method of trouble shooting of instrumentation was presented. Through the estimation of methods, it is concluded that the Eltinge method contains inherently the most perfect thermal dissociation model as far as the exhaust composition is concerned; therefore, this might be regarded as the most general equation of AFR determination among the existing ones. The others might be considered as approximate form. In addition, the mal-distribution factor in Eltinge method is qualitatively equivalent to thermal dissociation chemical equilibrium constant K. Lastly, it is illustrated that all instrumentation error, including the sampling line leakage, can be easily detected through the analyzing the exhaust component on the Eltinge chart.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.25 no.1
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• pp.23-34
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• 1997

Seismic tomography using the graph theoretical method of ray tracing is performed in two synthetic data sets with laterally varying velocity structures. The straight-ray tomography shows so poor results in imaging the laterally varying velocity structure that the ray-traced tomographic techniques should be used. Conventional ray tracing methods have serious drawbacks, i.e. problems of convergence and local minima, when they are applied to seismic tomography. The graph theretical method finds good approximated raypaths in rapidly varying media even in shadow zones, where shooting methods meet with convergence problems. The graph theoretical method ensures the globally minimal traveltime raypath while bending methods often cause local minima problems. Especially, the graph theoretical method is efficient in case that many sources and receivers exist, since it can find the traveltimes and corresponding raypaths to all receivers from a specific source at one time. Moreover, the algorithm of graph theoretical method is easily applicable to the ray tracing in anisotropic media, and even to the three dimensional case. Among the row-active inversion techniques, the conjugate gradient (CG) method is used because of fast convergence and high efficiency. The iterative sequence of the ray tracing by the graph theoretical method and the inversion by the CG method is an efficient and robust algorithm for seismic tomography in laterally varying velocity structures.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.3
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• pp.312-320
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• 1998

The purpose of this study is to investigate and compare the validity of various visual simulation methods with or without sounds and videos of the landscapes The landscape evaluation through such media as color slide, color slide with sounds, video and video without sounds are compared with on-site evaluaton of the landscape. The results are as follows : ·Video can generally convey the feelings for the real landscapes better than traditonal mathod, i.e., slide without sounds. ·When the sources of sounds are dominant in the view, there are great differences in responses among 4 different media and video can convey the feelings for real landscapes on site most successfully. ·There are slight differences by landscape types ; in mixed landscapes, there are higher correlations between the on-site estimaton and estimations through media ; in natural landscapes, video can reflect the feelings for real landscapes on site better. ·There is little difference between two shooting methods, fixed shot and pan shot. These results suggest that traditional visual simulation, with slides or photographs, could not reflect the real landscapes in certain situations and the visual simulation method with sounds and videos should be used in such situatios to represent the real landscape better. Especially, when the whole and comprehensive evaluatio of the landscape properties is important, the visual simulation with sounds and videos should be used. And simulation techniques with sounds and videos should be further developed for practial applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.5
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• pp.1871-1890
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• 2021

The transition toward a contactless society has been rapidly progressing owing to the recent COVID-19 pandemic. As a result, the IT environment of organizations and enterprises is changing rapidly; in particular, data security is expanding to the private sector. To adapt to these changes, organizations and companies have started to securely transfer confidential data to residential PCs and personally owned devices of employees working from home or from other locations. Therefore, organizations and companies are introducing streaming data services, such as the virtual desktop infrastructure (VDI) or cloud services, to securely connect internal and external networks. These methods have the advantage of providing data without the need to download to a third terminal; however, while the data are being streamed, attacks such as screen shooting or capturing are performed. Therefore, there is an increasing interest in prevention techniques against screen capture threats that may occur in a contactless environment. In this study, we analyze possible screen capture methods in a PC and a mobile phone environment and present techniques that can protect the screens against specific attack methods. The detection and defense for screen capture of PC applications on Windows OS and Mac OS could be solved with a single agent using our proposed techniques. Screen capture of mobile devices can be prevented by applying our proposed techniques on Android and iOS.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.2
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• pp.175-184
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• 2013

In counterfire warfare, it is important to detect and attack enemy targets faster than the enemy using sensing and shooting assets. The artillery assets of North Korea are mostly mine artillery and much more than those of South Korea. To cope with sudden fire attacks from North Korea, we need to improve capability of our artillery. In this paper, we discuss issues and problems of our counterfire warfare systems and processes to overcome numerical inferiority and defend against the mine artillery. We develop a simulation model for counterfire warfare and analyze effectiveness of our counterfire weapon systems and operations based on various counterfire warfare scenarios. Finally, we propose methods of tactical operations and acquisition strategies of counterfire weapon systems, including detaction, firing, and protection assets.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.6
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• pp.743-754
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• 2015

FASCAM is a newly introduced mean against enemy fire power and supposed to be scattered on base areas in front of a tunnel so as to deter maneuver and shooting of enemy artilleries. However, for its characteristics different from conventional munitions, only a few studies have been undertaken on operations system using this new measure. In this research, we propose a procedure to describe and analyze mathematically an operation system for suppression of enemy fire power using FASCAM. Two suggested simulation methods, impact point generation and density integration, both can describe the actual operation rationally and each has advantages of its own respectively. Further, we demonstrated an example analysis to derive an optimal suppression plan based on the proposed procedure.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.3
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• pp.441-453
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• 2017

In this paper, a new type of weapon-target assignment(WTA) problem has been suggested that reflects realistic constraints for sharing target with other weapons and shooting double rapid fire. To utilize in rapidly changing actual battle field, the computation time is of great importance. Several metaheuristic methods such as Simulated Annealing, Tabu Search, Genetic Algorithm, Ant Colony Optimization, and Particle Swarm Optimization have been applied to the real-time WTA in order to find a near optimal solution. A case study with a large number of targets in consideration of the practical cases has been analyzed by the objective value of each algorithm.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.569-571
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• 1998

In this paper, we propose a method of restoring blurred images by an edge-sensitive adaptive filter. The direction of the edge is estimated using the properties of 2-D block FFT. Reduction of blurring due to the added noise during image transfer and the focus of lens caused by shooting a fast moving object is very important. To remove this phenomenon effectively, we can use the edge information obtained by processing the blurred images. The proposed algorithm estimates both the existence and the direction of the edge. On the basis of the acquired edge direction information, we choose the appropriate edge-sensitive adaptive filter, which enables us to get better images than images obtained by methods not considering the direction of the edge. The performance of the proposed algorithm is shown in the simulation result.

• International Journal of Advanced Culture Technology
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• v.5 no.1
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• pp.40-50
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• 2017

Taepyungmu is a performing art that can be called the most skillful dance among Korean dances. It expresses the meaning of honoring the peace and peacefulness of the country in dance. The construction of 3D stereoscopic digital contents for Taepyungmu is in a series of processes such as 3D recording of intangible cultural properties and implementation of hologram contents. The purpose is to try various possibilities through various technologies and methods, to establish a technical basis of the preservation paradigm change of intangible cultural properties and to present a leading direction to realize real digital cultural properties.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.205-207
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• 2020

This paper proposes a novel deep learning-based method to upsample a depth map. Most conventional methods estimate high-resolution depth map by modifying pixel value of given depth map using high-resolution color image and low-resolution depth map. However, these methods cause under- or over-shooting problems that restrict performance improvement. To overcome these problems, the proposed method iteratively performs grid warping scheme which shifts pixel values to restore blurred image for estimating high-resolution depth map. Experimental results show that the proposed method improves both quantitative and visual quality compared to the existing method.