• 천문학논총
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• 제22권4호
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• pp.113-132
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• 2007

On the framework of stochastic gravitational wave background(SGWB) by compact binary systems, we studied the strain spectra of SGWB produced by cosmological cataclysmic variables(CV). For this we reviewed the empirical properties of CVs by using newly published CV catalogue and calculated the cosmological densities of CVs considering the galaxy luminosity function and cosmic stellar birth rate function. Assuming the secular evolution of CVs, we calculated the time scale of CV gravitational wave(GW) radiation and derived formulae for the strain spectra of SGWB by cosmological CVs.

• 천문학회보
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• 제39권1호
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• pp.77.1-77.1
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• 2014

Gravitational waves predicted by the general relativity almost 100 years ago have been implicated indirectly only by astrophysical observations such as the orbital evolution of binary pulsars. The advanced detectors of gravitational waves will become operational in a few years and they are expected to make direct detection of gravitational wave signal coming from merging of binaries composed of neutron stars or stellar mass black holes from external galaxies. Korean Gravitational Wave Group (KGWG) is contributing to the possible detection through the data analysis of LIGO and Virgo. We summarize the perspectives of the gravitational wave research and the impacts of the detection in the near future in astronomy and astrophysics.

• 천문학논총
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• 제30권2호
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• pp.197-200
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• 2015

Several contact binary systems in four stellar clusters or their fields are reported here; NGC7789-V12, EP Cep and ES Cep in NGC188, NGC104-V95 and V710 Mon. Their multiple light curves were analyzed by the 2010 version of the W-D code, and their physical parameters were obtained.

• 한국콘텐츠학회논문지
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• 제20권12호
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• pp.278-286
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• 2020

죄수 딜레마 게임은 게임 이론의 대표적인 사례로 많은 경제학자, 사회과학자 및 컴퓨터 과학자가 관심을 가지고 연구하고 있다. 근래에는 죄수 딜레마 게임 분석을 위해 유전 알고리즘, 입자 군집 최적화 등의 진화 연산 기법을 적용한 계산적 접근에 대한 연구가 활발히 이루어져 왔다. 본 연구에서는 3가지의 서로 다른 이진입자 군집 최적화 기법을 사용하여 2명 또는 그 이상의 플레이어가 참여하는 반복 죄수 딜레마 게임에 대한 전략을 진화시켜보고자 한다. 반복 죄수 딜레마 게임에 3가지 버전의 이진 입자 군집 최적화를 적용하여 실험한 결과 자신의 이득을 최대화하기 위한 이기적인 참가들 사이에서도 상호 협력 관계가 구축될 수 있음을 확인하였나 참여자가 많을수록 상호 협력 관계가 구축이 어려워 짐을 확인하였다.

• Journal of Astronomy and Space Sciences
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• 제24권1호
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• pp.31-38
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• 2007

We have investigated the evolutionary status of 85 Peg within the framework of standard evolutionary theory. 85 Peg has been known to be a visual and spectroscopic binary system in the solar neighborhood. In spite of the accurate information of the total mass (${\sim}1.5M_{\odot}$) and the distance (${\sim}12pc$) from the HIPPARCOS parallax, it has been undetermined an individual mass, therefore the evolved status of the system. Moreover, the coupled uncertainties of chemical composition and age, make matters worse in predicting an evolutionary status of the system. Nevertheless, we computed the various possible models for 85 Peg, and then calibrated stellar parameters by adjusting to the recent observational data. Our modelling computation has included recently updated input physics and stellar theory such as opacity, equation of state, and chemical diffusion. Through a statistical assessment, we have derived a confident parameter set as the best solution which minimized $X^{2}$ within the observational error domain. Most of all, we found that 85 Peg is not a binary system but a triple system with an unseen companion 85 Peg $B_{b}\;{\sim}0.16M_{\odot}$. The aim of the present paper is (1) to provide a complete modelling of the stellar system based on the evolutionary theory, and (2) to constrain the physical dimensions such as mass, metallicity and age.

• 한국지능시스템학회논문지
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• 제13권1호
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• pp.37-44
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• 2003

본 논문은 DNA coding 방법과 Genetic Algorithm(GA)을 사용하여 numeric(0~9) 패턴인식 성능을 비교 평가하였다. 이진스트링의 개체 집단 위에서 모의진화를 일으켜 효율적으로 최적 해를 탐색하는 GA와, 생체 분자인 DNA를 계산의 도구 및 정보 저장도구로 사용하며, Adenine(A), Cytosine(C), Guanine(G), Thymine(T)등의 4가지 염기를 사용하는 DNA coding 방법을 이용하여 numeric 패턴인식을 수행하였다. DNA coding 방법과 GA의 성능을 비교 평가하기 위해서 selection, crossover, mutation 등의 GA연산자를 DNA coding에 동일하게 적용하였다. 실험결과, DNA coding 방법은 GA보다 효과적으로 패턴인식을 수행하였다. GA에 비해 DNA coding 방법의 장점은 스트링의 길이가 가변적이고 해의 중복성을 가지며, 4가지 염기를 이용하기 때문에 해 표현이 다양함을 가지고 있다.

• 천문학회보
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• 제35권2호
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• pp.72.2-72.2
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• 2010

The extremely metal-poor halo planetary nebula BoBn 1 has been investigated based on IUE archive data, Subaru/HDS spectra, VLT/UVES archive data, and Spitzer/IRS spectra. We have measured a heliocentric radial velocity of $+191.6\pm1.3\;kms^{-1}$ and expansion velocity 2Vexp of $40.5\pm3.3\;kms^{-1}$ from an average over 300 lines. The estimations of C, N, O, and Ne abundances from the optical recombination lines (ORLs) and Kr, Xe, and Ba from the collisional excitation lines (CELs) are also done. We have detected 5 fluorine and several slow neutron capture elements (the s-process). The amounts of [F/H], [Kr/H], and [Xe/H] suggest that BoBn 1 is the most F-rich among F detected PNe and is a heavy s-process element rich PN. The photo-ionization models built with non-LTE theoretical stellar atmospheres indicate that the progenitor was a 1-1.5 $M_\bigstar$ that would evolve into a white dwarf with an $0.62M_{\odot}$ core mass and $0.09M_{\odot}$ ionized nebula. Careful examination implies that BoBn 1 has evolved from a binary and experienced coalescence during the evolution to become a visible PN. The elemental abundances except N could be explained by a binary model composed of $0.75M_{\odot}+1.5M_{\odot}$ stars.

• 천문학회보
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• 제37권2호
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• pp.141.2-141.2
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• 2012

We present photometric solutions of the 26,212 eclipsing binaries discovered in the LMC by Graczyk et al. (2011). They published that 70 percent of a total are detached systems. Another 25 and 5 percent are semi-detached and contact binaries, respectively. We discovered that 21 percent of 26,121 eclipsing binary stars are eccentric orbit systems. The binary star distribution in the LMC is different from those of the Galactic center direction (Bade window). It is very interesting that there are only 5 of 357 (2 percent) stars have eccentric orbit in the Galactic Center (Kang 2011). We selected the light curve of 18,274 detached systems. Then we estimated the fundamental parameters on the basis of their photometric solutions and the semi-major-axis (a) assuming the distance modulus to the LMC~18.50. We compared the estimated fundamental parameters with an empirical mass-luminosity relation and consistency between mass-radius relation base on stellar evolution model in the low metallicity (Z=0.008) by Bertelli et al. (2009). This method allows for independent determine of the fundamental parameters of the eclipsing binaries in the LMC without the radial velocity curves.

• International Journal of Computer Science & Network Security
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• 제21권8호
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• pp.196-202
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• 2021

DNA sequencing provides fundamental data in genomics, bioinformatics, biology and many other research areas. With the emergent evolution in DNA sequencing technology, a massive amount of genomic data is produced every day, mainly DNA sequences, craving for more storage and bandwidth. Unfortunately, managing, analyzing and specifically storing these large amounts of data become a major scientific challenge for bioinformatics. Those large volumes of data also require a fast transmission, effective storage, superior functionality and provision of quick access to any record. Data storage costs have a considerable proportion of total cost in the formation and analysis of DNA sequences. In particular, there is a need of highly control of disk storage capacity of DNA sequences but the standard compression techniques unsuccessful to compress these sequences. Several specialized techniques were introduced for this purpose. Therefore, to overcome all these above challenges, lossless compression techniques have become necessary. In this paper, it is described a new DNA compression mechanism of pattern matching extended Compression algorithm that read the input sequence as segments and find the matching pattern and store it in a permanent or temporary table based on number of bases. The remaining unmatched sequence is been converted into the binary form and then it is been grouped into binary bits i.e. of seven bits and gain these bits are been converted into an ASCII form. Finally, the proposed algorithm dynamically calculates the compression ratio. Thus the results show that pattern matching extended Compression algorithm outperforms cutting-edge compressors and proves its efficiency in terms of compression ratio regardless of the file size of the data.

• Journal of Astronomy and Space Sciences
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• 제33권3호
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• pp.185-196
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• 2016

New multiband BVRI light curves of NSVS 1461538 were obtained as a byproduct during the photometric observations of our program star PV Cas for three years from 2011 to 2013. The light curves indicate characteristics of a typical W-subtype W UMa eclipsing system, displaying a flat bottom at primary eclipse and the O'Connell effect, rather than those of an Algol/b Lyrae eclipsing variable classified by the northern sky variability survey (NSVS). A total of 35 times of minimum lights were determined from our observations (20 timings) and the SuperWASP measurements (15 ones). A period study with all the timings shows that the orbital period may vary in a sinusoidal manner with a period of about 5.6 yr and a small semi-amplitude of about 0.008 day. The cyclical period variation can be interpreted as a light-time effect due to a tertiary body with a minimum mass of 0.71 M_⊙. Simultaneous analysis of the multiband light curves using the 2003 version of the Wilson-Devinney binary model shows that NSVS 1461538 is a genuine W-subtype W UMa contact binary with the hotter primary component being less massive and the system shows a low mass ratio of q(m_c/m_h)=3.51, a high orbital inclination of 88.7°, a moderate fill-out factor of 30 %, and a temperature difference of ΔT=412 K. The O'Connell effect can be similarly explained by cool spots on either the hotter primary star or the cool secondary star. A small third-light corresponding to about 5 % and 2 % of the total systemic light in the B and V bandpasses, respectively, supports the third-body hypothesis proposed by the period study. Preliminary absolute dimensions of the system were derived and used to look into its evolutionary status with other W UMa binaries in the mass-radius and mass-luminosity diagrams. A possible evolution scenario of the system was also discussed in the context of the mass vs mass ratio diagram.