• Journal of Astronomy and Space Sciences
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• 제29권1호
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• pp.51-55
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• 2012

A few high-mass X-ray binaries-consisting of an OB star plus compact companion-have been observed by Fermi and ground-based Cerenkov telescopes like High Energy Stereoscopic System (HESS) to be sources of very high energy (VHE; up to 30 TeV) ${\gamma}$-rays. This paper focuses on the prominent ${\gamma}$-ray source, LS 5039, which consists of a massive O6.5V star in a 3.9-day-period, mildly elliptical ($e{\approx}0.24$) orbit with its companion, assumed here to be an unmagnetized compact object (e.g., black hole). Using three dimensional smoothed particle hydrodynamics simulations of the Bondi-Hoyle accretion of the O-star wind onto the companion, we find that the orbital phase variation of the accretion follows very closely the simple Bondi-Hoyle-Lyttleton (BHL) rate for the local radius and wind speed. Moreover, a simple model, wherein intrinsic emission of ${\gamma}$-rays is assumed to track this accretion rate, reproduces quite well Fermi observations of the phase variation of ${\gamma}$-rays in the energy range 0.1-10 GeV. However for the VHE (0.1-30 TeV) radiation observed by the HESS Cerenkov telescope, it is important to account also for photon-photon interactions between the ${\gamma}$-rays and the stellar optical/UV radiation, which effectively attenuates much of the strong emission near periastron. When this is included, we find that this simple BHL accretion model also quite naturally fits the HESS light curve, thus making it a strong alternative to the pulsar-wind-shock models commonly invoked to explain such VHE ${\gamma}$-ray emission in massive-star binaries.

• Journal of Astronomy and Space Sciences
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• 제4권1호
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• pp.11-23
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• 1987

외신성의 폭발 원인을 반성으로부터 accretion disk에 흘러들어온 물질유입량의 갑작스런 증가로 가정하였다. 따라서 $\alpha$-disk모델에서 source term을 100배로 증가시켜 Newton-Raphson 방법으로 풀었다. 구해진 disk의 물리적 변수들을 disk의 반경에 대해 나타냈으며, 시간에 따른 disk의 광도와 질량 변화를 구하였다. $\alpha$ 의 값을 각각 0.1, 0.12, 0.15, 0.18로 바꿔가며 유입되는 물질의 양이 일정할 때와 disk의 밝기가 가장 밝을 때의 변수들을 비교하였다. 이들 결과를 $1M_\bigodot$의 항성의 표면과 대기와 비교하였다.

• 대한수학회보
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• 제52권3호
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• pp.1035-1046
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• 2015

In this work we present some geometric properties (like star-likeness and convexity of order ${\alpha}$ and also close-to-convexity of order ($1+{\alpha}$)/2) for normalized of Lommel functions of the first kind. In order to prove our main results, we use the technique of differential subordinations and some inequalities. Furthermore, we present some applications of convexity involving Lommel functions associated with the Hardy space of analytic functions, i.e., we obtain conditions for the function $h_{{\mu},{\upsilon}}(z)$ to belong to the Hardy space $H^p$.

• 대한수학회보
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• 제55권1호
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• pp.149-163
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• 2018

In recent years, the study of slice Dirac operators has attracted more and more attention in the literature. In this paper, Almansitype decompositions for null solutions to the iterated slice Dirac operator and the generalized slice Dirac operator are obtained without a star-like domain centered at the origin. As applications, we investigate Riquier type problems and Dirichlet type problems in the theory of slice monogenic functions.

• Animal Systematics, Evolution and Diversity
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• 제26권3호
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• pp.349-351
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• 2010

Some asteroid specimens were collected from the subtidal zone near Gapado, Jejudo Island with fishing net on June 2010. Among them, Anseropoda petaloides (Goto, 1914) which belongs to the family Asterinidae of the order Valvatida turned out to be a new record from Korea. Morphological characters of this species collected at 130 m deep are redescribed with photographs. This species is characterized by its very thin body composed of plates imbricated into each other like scales. Twenty four asteroids are currently known from Jejudo Island, Korea.

• International Journal of Contents
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• 제1권2호
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• pp.44-47
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• 2005

One of the most important characteristics in Hollywood movies is that Hollywood movies have created heroes. But, the meaning of heroes in Hollywood movies is different from proto- typical heroes. America has such a short history, so it doesn't have the mythology. It is also consist of multi-race, culture. Thus, America people, especially governor need something that tie up governed people spiritually. Hollywood film industry has responded about this expectation since 1920's. Hollywood film producers have created mythology and hero like the western genre and Rambo. Now days, America, as only super power, wants to spread it's mythology and heroes over the world. That is cultural Imperialism.

• 대한수학회논문집
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• 제37권1호
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• pp.113-123
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• 2022

In the present paper, we introduce the subclasses 𝔅_1Σ(𝜇), B_1Σ(𝜇, 𝛾) and U_Σ(𝜇, 𝛾) of bi-univalent Bazilevič functions which are defined in the open unit disk 𝔻. Further, we obtain sharp estimates on initial coefficients a₂, a₃, a₄ and also sharp estimate on the Fekete-Szegö functional a₃ - ka²₂ for the functions belong to these subclasses.

• 천문학회보
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• 제46권1호
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• pp.33.3-34
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• 2021

In LCDM universe, large, massive structures, like galaxy clusters, grow through the successive accretion/mergers of smaller structures. Therefore, at high redshift, unlike local, it is expected that there would be plenty of galaxy clusters which are still growing. Here, we report the discovery of a high-redshift (z~1) galaxy cluster which is in its active formation stage. This cluster is well connected to the large scale overdense environment and contains high fraction of star-forming galaxies, providing a good example supporting our previously suggested 'Web-feeding model'.

• 천문학회보
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• 제43권1호
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• pp.55.1-55.1
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• 2018

Studies on rotation-powered pulsars with strong surface magnetic field may help us clarify the unclear link between magnetars and canonical radio pulsars because the magnetar-like emission is expected to be observed. PSR J1119-6127 associated with SNR G292.2-0.5 has a high magnetic field of $4.1{\times}1013$ gauss, and a young characteristic age of ~1700 years can be served as the good candidate to compare with magnetars and rotation-powered pulsars. The glitch accompanied by the radiative changes detected in 2007 is the first case we observed for a rotationally powered radio pulsar. This pulsar experienced magnetar-like outbursts in mid. 2016, similar to the 2006 transition occurred on the other radio-quiet rotation-powered pulsar with strong surface magnetic field, PSR J1846-0258. In this talk, I'll report the investigation with X-ray and gamma-ray data of this magnetar-like pulsar. A sudden decrease in the gamma-ray emission at the GeV band was detected immediately after the X-ray outburst. Accompanying with the disappearance of the radio pulsation, the gamma-ray pulsation cannot be resolved as well after the outburst. We tried to derive the timing behavior and some intriguing features of this pulsar in this work corresponding to the outburst using the Swift data, NuSTAR and XMM observations.

• 한국식품과학회지
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• 제32권3호
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• pp.706-712
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• 2000

26종의 향신료와 이들 향신료를 사용하여 제조하는 instant curry 제품의 SOD 유사활성을 측정한 결과 모든 시료에서 SOD 유사활성이 나타났으며 그 중 clove가 $232,143{\pm}19.989\;unit/g$로 가장 높았고, rosemary, cassia, tarragon, allspice, oregano, bay leaves, basil, marjoram, thyme, star anise등에서도 g당 $10^5\;unit$ 이상이었다 시판되는 10종의 instant curry제품을 사용하여 $100^{\circ}C$에서 10분간 가열 후 SOD 유사활성을 측정한 결과 g당 $400{\sim}700$ units 정도였다. Nitrite 분해능을 확인한 결과 26종 향신료의 상온수 추출물($(25^{\circ}C)$과 열수 추출물$(100^{\circ}C)$ 그리고, instant curry 10종의 열수 추출물에서 모두 nitrite 분해능을 확인할 수 있었다. pH 1.2에서 상온수 추출물의 경우 clove가 $(97.58{\pm}0.88%)$로 가장 높은 분해율을 나타냈으며 cassia, bay leaves, allspice, oregano, staranise, rosemary, tarragan의 경우도 90% 이상의 분해율을 보여주었다. 그리고 열수 추출물의 경우에도 상온수 추출물과 거의 유사한 nitrite 분해율을 나타내었다. Instant curry의 원료로 사용되는 pure curry의 경우 숙성기간(0주${\sim}$12주)에 따른 nitrite 분해능을 측정한 결과 pH 1.2에서 $50{\sim}60%$ 정도였으며 숙성기간 중 변화가 없는 것으로 밝혀졌다. 또한 instant curry 제품을 사용하여 pH 1.2 조건하에서 nitrite 분해능을 측정한 결과 제품별 차이는 있었으나 12${\sim}$28% 정도의 분해능을 가지고 있었다.