• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.260-261
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• 2003

위상 부호 다중화 시스템에서 cross talk 잡음은 기준빔 성분들간의 180$^{\circ}$와 다른 위상 천이 오차, 기준빔 성분들의 Bragg 격자로부터 불균일한 회절 세기들, 혹은 non-Bragg-matched 격자로부터 회절 때문에 발생하는 것으로 알려져 있다. 본 논문에서는 cross talk의 다른 원인들이 최소화된 시스템에서 위상 천이 오차만이 존재할 때 이전 연구들과 달리 유한한 contrast ratio를 갖는 이진 랜덤 이차원 이미지들을 광굴절 결정체에 위상 부호 다중화하고 복원할 때 얻어지는 신호대 잡음비(SNR)을 계산하고 이를 실험 측정 결과와 비교한다. (중략)

• Journal of Information Processing Systems
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• v.15 no.1
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• pp.169-180
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• 2019

Transmitting visual information over a broadcasting network is not only prone to a copyright violation but also is a forgery. Authenticating such information and protecting its authorship rights call for more advanced data encoding. To this end, electronic watermarking is often adopted to embed inscriptive signature in imaging data. Most existing watermarking methods while focusing on robustness against degradation remain lacking of measurement against security loophole in which the encrypting scheme once discovered may be recreated by an unauthorized party. This could reveal the underlying signature which may potentially be replaced or forged. This paper therefore proposes a novel digital watermarking scheme in temporal-frequency domain. Unlike other typical wavelet based watermarking, the proposed scheme employed the Lorenz chaotic map to specify embedding positions. Effectively making this is not only a formidable method to decrypt but also a stronger will against deterministic attacks. Simulation report herein highlights its strength to withstand spatial and frequent adulterations, e.g., lossy compression, filtering, zooming and noise.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.38.1-38.1
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• 2018

A merging galaxy cluster is a useful laboratory to study many interesting astrophysical processes such as intracluster medium heating, particle acceleration, and possibly dark matter self-interaction. However, without understanding the merger scenario of the system, interpretation of the observational data is severely limited. In this work, we focus on the off-axis binary cluster merger Abell 115, which possesses many remarkable features. The cluster has two cool cores in X-ray with disturbed morphologies and a single giant radio relic just north of the northern X-ray peak. In addition, there is a large discrepancy (almost a factor of 10) in mass estimate between weak lensing and dynamical analyses. To constrain the merger scenario, we perform a hydrodynamical simulation with the adaptive mesh refinement code RAMSES. We use the multi-wavelength observational data including X-ray, weak-lensing, radio, and optical spectroscopy to constrain the merger scenario. We present detailed comparisons between the simulation results and these multi-wavelength observations.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.40.1-40.1
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• 2018

Among Type I supernovae, which show no evidence for hydrogen lines in spectra, Type Ib/c supernovae lack of strong Si absorption lines and are involved with massive progenitors. While strong helium absorption lines are present in Type Ib supernovae, narrow helium emission lines also can appear in some Type Ib that are often called Type Ibn supernovae (SNe Ibn). We consider helium giant stars as a promising progenitor candidate for SN Ibn and suggest the evolutionary scenario through binary systems using MESA code. In our models the range of primary mass is 11 - 20 solar mass, mass ratio is 0.5 - 0.9, and initial period is 1.5 / 1.7 / 2.0 / 2.5 / 3.0 day. In particular, we find that the evolution of the secondary star can overtake the primary through mass transfer from the secondary to the primary, which is so-called 'reverse case B' mass transfer. In such systems the secondary star may undergo a supernova explosion earlier than the primary star. In this case, the primary star evolves towards a single helium giant to become a SN Ibn progenitor. These cases are more frequent in relatively low initial primary mass.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.60-63
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• 2011

프로그램 코드는 실행이 되기 전에 반드시 주 기억 장치에 Loading 되어야 하는데, 이때 Loading Time 은 압축 데이터를 NAND Flash Memory 로부터 읽어오는 시간과 압축을 복원하는 시간의 합이 된다. 따라서 빠른 압축 복원 속도는 코드 압축을 사용하는 임베디드 장치에서는 매우 중요한 요소가 된다. 일반적으로 휴대 장치의 경우 일반 PC 와는 달리 적은 배터리 용량 및 프로세서의 한계, 프로그램을 저장하는 NAND Flash Memory 의 크기 때문에 최적의 성능을 발휘할 수 없었다. 본 논문에서는 무 손실 압축 알고리즘에 대한 연구를 진행 함과 동시에 모바일 환경에 적합한 LZCode 을 개선하여 복원속도를 기존 LZCode 보다 1.5 배 향상 시키는 알고리즘을 제시 하고자 한다.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.1
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• pp.71-75
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• 2008

Many sensor operating systems have memory limitation constraint; therefore, stack memory areas of threads resides in a single memory space. Because most target platforms do not have hardware MMY (Memory Management Unit), it is difficult to protect each stack area. The method to solve this problem is to exchange original stack handling instructions in binary code for wrapper routines to protect stack area. In this exchanging phase, instruction corruption problem occurs due to difference of each instruction length between stack handling instructions and branch instructions. In this paper, we propose the algorithm to call a target routine without instruction corruption problem. This algorithm can reach a target routine by repeating branch instructions to have a short range. Our solution makes it easy to apply security patch and maintain upgrade of software of sensor node.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.1
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• pp.1-9
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• 2013

This paper proposes a matching algorithm to find corresponding polygon feature sets between heterogeneous digital maps. The algorithm finds corresponding sets in terms of optimizing their shape similarities based on the assumption that the feature sets describing the same entities in the real world are represented in similar shapes. Then, by using a binary code, it is represented that a polygon feature is chosen for constituting a corresponding set or not. These codes are combined into a binary string as a candidate solution of the matching problem. Starting from initial candidate solutions, a genetic algorithm iteratively optimizes the candidate solutions until it meets a termination condition. Finally, it presents the solution with the highest similarity. The proposed method is applied for the topographical and cadastral maps of an urban region in Suwon, Korea to find corresponding polygon feature sets for block areas, and the results show its feasibility. The results were assessed with manual detection results, and showed overall accuracy of 0.946.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.3
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• pp.134-142
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• 2002

Quadtree, which is a hierarchical data structure, is a very important data structure to represent binary images. The linear quadtree representation as a way to store a quadtree is efficient to save space compared with other representations. Therefore, it has been widely studied to develop efficient algorithms to execute operations related with quadtrees. The window operation is one of important geometry operations in image processing, which extracts a sub-image indicated by a window in the image. In this paper, we present an algorithm to perform the window operation of binary images represented by quadtrees, using three-dimensional $n{\times}n{\times}n$ processors on RMESH(Reconfigurable MESH). This algorithm has constant-time complexity by using efficient basic operations to route the locational codes of quardtree on the hierarchical structure of $n{\times}n{\times}n$ RMESH.

• Journal of Astronomy and Space Sciences
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• v.24 no.2
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• pp.99-110
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• 2007

A total of 824 observations (206 in ${\Delta}B$, 206 in ${\Delta}V$, 206 in ${\Delta}R$, 206 in ${\Delta}I$ for CC Com were made on 3 nights from March 3 to April 3 in 2002 using the 61cm telescope with 2K CCD camera of the Sobaeksan Optical Astronomy Observatory of KASI. From our observations 9 times of minimum light were newly determined. Combined analysis of our new BVRI light curves with the double-lined radial velocity curves of Pribulla et al. (2007) were made with the 2004 Wilson-Devinney(WD) binary model code to yield new physical parameters of the CC Com system. Small asymmetries in light curves were explained with the adoption of two hot spots on the cool secondary.

• Journal of KIISE:Software and Applications
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• v.36 no.9
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• pp.758-766
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• 2009

In this days, the concept of time-to-market is important in embedded systems in consumer electronics. According to the short time of development period, it is also important in development of Software Development toolkits (SDKs). However, it is not improved to the development time of SDKs specialized in new processors. In this point, the Architecture Description Language (ADL) is an alternative to relieve the pain of building the SDKs as the required SDKs can be automatically generated from ADL for the processor. In this paper, we automatically generate SDKs specialized in processors using GNU Binutils. Through this research, we can more easier and faster produce the SDKs such as assembler and linker than by using handcrafted code.