• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.117-119
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• 2006

In this work, we suggest another method to localize DFT in spatial domain. This enables DFT algorithm to be used for local pattern matching. Once calculated, it costs same load to calculate localized DFT regardless of the size or the position of local region In spatial domain. We applied this method to face detection problem and got the results which prove the utility of our method.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1831-1833
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• 1998

In this paper, A complex-image method(CIM) and efficient numerical integration algorithm is implemented to evaluate the spatial-domain Green's function through the Sommerfeld-type integral with a thick substrate. CIM is compared to numerical integration technique.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1409-1415
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• 2010

In this paper we proposed the watermarking technique using the markspace which is selected by tree-structure between the subbands in the wavelet domain and feature information in the spatial domain. The watermarking candidate region in the wavelet domain is obtained by the markspace selection algorithm divides the highest frequency subband to several segments and calculates theirs energy and the averages value of the total energy of the subband. Also the markspace of the spatial domain is obtained by the boundary information of a image. The final markspace is selected by the markspaces of the wavelet and spatial domain. The watermark is embedded into the selected markspace using the random addresses by LFSR. Finally the watermarking image is generated using the inverse wavelet transform. The proposed watermarking algorithm shows the robustness against the attacks such as JPEG, blurring, sharpening, and gaussian noise.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.117-124
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• 2004

Various multimedia systems have been developed and their application areas widely proliferate. Thus, the interoperability is getting important among various networks and devices. The video transcoding is a technology to solve this interoperability problem among various coding standards. Transcoding can be defined as the conversion of one compressed coded data to another. In this paper, MPEG-2 to MPEG-4 transcoder in the spatial domain is compared with that in the DCT domain. The transcoder is very useful when a video sequence that is originally encoded for digital TV, DVD or satellite broadcasting is served in mobile environment. In order to compare two transcoders, all modules except motion compensation and down sampling are implemented identically. In addition, both transcoders do not search for motion vector. Instead, the decoded information is reused to the encoder. The experimental results show that the transcoder in the spatial domain is usually better than that in the DCT domain with respect to PSNR (Peak Signal-to-Noise Ratio), bitrate and execution time.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.5 s.311
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• pp.57-67
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• 2006

Intellectual property rights are gathering strength theses days. Because digital contents are easily reproduced and distributed by advanced computers and networks. Digital watermarking is one of the best solutions for this problem. Generally, frequency-domain watermarking algorithms are preferred since they are more robust than spatial-domain algorithms. However, coefficients in the frequency domain are floating-point numbers. Thus, it is not easy to manipulate those floating-point coefficients and frequency-domain watermarking algorithms have some limitations in their applications. In order to overcome this difficulty, we employ an integer transform in this paper. In addition, our proposed algerian can extract the watermark from both the spatial and frequency domains. We embed the watermark into a specific bit-plane of mid-frequency coefficients. This is equivalent to the differential energy watermarking (DEW) in the spatial domain. Our simulation results show that the proposed algorithm is imperceptible, good for the watermark payload, and robustness against various attacks. Moreover, it is more efficient than any other algorithm working in only one domain.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.71-77
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• 2018

The optical time domain reflectometer (OTDR) is the most widely used method to monitor problems with currently installed optical fibers. The OTDR is an instrument designed to test the FTTx network and evaluates the physical properties of the fiber, such as transmission loss and connection loss. It is important to improve the spatial resolution in order to accurately grasp the optical path problems by using the OTDR. When the pulse width is less than twice the distance between the two reflectors, the signals reflected from the two reflectors are reflected without overlap, so that the reflected signal can be distinguished. However, when the pulse width is larger than twice the distance between the two reflectors, so that the reflected signal can not be distinguished. In order to overcome these limitations, this paper proposed a method of improving spatial resolution by applying a super resolution algorithm. As a result of the simulation, the resolution is improved when the super resolution algorithm is applied, and the event interval can be analyzed more precisely.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.677-684
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• 2009

With various sensor network and ubiquitous technologies, we can extend interaction area from a virtual domain to physical space domain. This spatial interaction is differ in that traditional interaction is mainly processed by direct interaction with the computer machine which is a target machine or provides interaction tools and the spatial interaction is performed indirectly between users with smart interaction tools and many distributed components of space. So, this interaction gives methods to users to control whole manageable space components by registering and recognizing objects. Finally, this paper provides an effective spatial interaction method with template-based task mapping algorithm which is sorted by historical interaction data for support of users' intended task. And then, we analyze how much the system performance would be improved with the task mapping algorithm and conclude with an introduction of a GUI method to visualize results of spatial interaction.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.56-65
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• 2005

A dynamic analysis method that freezes a time domain by discretization and solves the spatial propagation equation has a unique feature that provides a degree of freedom on spatial domain compared with the space discretization or space-time discretization finite element method. Using this feature, the time finite element analysis can be effectively applied to optimize the spatial characteristics of distributed type actuators. In this research, the time domain finite element method was used to discretize the model. A state variable vector was used in the discretization to include arbitrary initial conditions. A performance index was proposed on spatial domain to consider both potential and vibrational energy, so that the resulting shape of the distributed actuator was optimized for dynamic control of the structure. It is assumed that the structure satisfies the final rest condition using the realizable control scheme although the initial disturbance can affect the system response. Both equations on states and costates were derived based on the selected performance index and structural model. Ricatti matrix differential equations on state and costate variables were derived by the reconfiguration of the sub-matrices and application of time/space boundary conditions, and finally optimal actuator distribution was obtained. Numerical simulation results validated the proposed actuator shape optimization scheme.

• Journal of Broadcast Engineering
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• v.6 no.2
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• pp.169-176
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• 2001

Most of the previous video watermarking algorithms cannot be supported by real-time video processing. The maul reason is that in order to develop a robust algorithm the watermarking technique requires a very high computational cost when embedding and extracting the watermark in various frequency domains. Previous embedding methods simultaneously try to compress a video by MPEG and embed a watermark supporting real-time processing. However, In this paper, our proposed algorithm can support real-time processing in both spatial and frequency domains. First. the watermark is created on the courier transform domain, and next is inverse-Fourier-transformed ; then, we directly embed it into the video frame In the spatial domain. This procedure does not require a lot of the computational cost during embedding because of the spatial domain processing. Also, it is possible to support a video stream service and a very robust algorithm from MPEG compression and various geometric attacks.

• Journal of the Korean Society for Railway
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• v.9 no.2 s.33
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• pp.187-192
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• 2006

The regularity of railway track alignment is a crucial component fur maintaining travel safety and the smoothness of passenger ride. The conventional spectral analysis has been considered to estimate the severity of the track irregularity from measured data. The time domain data used to be changed into the frequency domain by Fourier transform. Because the measuring points can be regarded as the time points, the spatial-frequency can be introduced instead of the time-frequency. Although FFT(Fast Fourier Transform) and/or PSD(Power Spectral Density) function could provide fairly localized information within frequency domain, but chronical configurations of data could be missed. In this study, we attempt to apply the Morlet wavelet transform for the purpose of a frequency-time-domain analysis rather than a frequency-domain analysis. The applicability of wavelet transform is examined for the estimation of the track irregularity with real measured track data on the section of Kyoung-bu line by EM-120 measuring vehicle. It is shown that the wavelet transform can be an effective tool to manage the track irregularity.