• 천문학회보
• /
• 제39권2호
• /
• pp.43.2-43.2
• /
• 2014

We present the three-dimensional genus topology of large-scale structure using the CMASS sample of the Final SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) data. To estimate the uncertainties in the measured genus, we very carefully construct mock CMASS surveys along the past light cone from the Horizon Run 3. We find that the shape of the observed genus curve agrees very well with the prediction of perturbation theory and with the mean topology of the mock surveys. However, comparison with simulations show that the observed genus curve slightly deviates from the theoretical Gaussian expectation. From the deviation, we further quantify the primordial non-Gaussian contribution.

• 천문학회지
• /
• 제50권3호
• /
• pp.41-49
• /
• 2017

We conduct BVRI and R band photometric observations of asteroid (5247) Krylov from January 2016 to April 2016 for 51 nights using the Korea Microlensing Telescope Network (KMTNet). The color indices of (5247) Krylov at the light curve maxima are determined as $B-V=0.841{\pm}0.035$, $V-R=0.418{\pm}0.031$, and $V-I=0.871{\pm}0.031$ where the phase angle is $14.1^{\circ}$. They are acquired after the standardization of BVRI instrumental measurements using the ensemble normalization technique. Based on the color indices, (5247) Krylov is classified as a S-type asteroid. Double periods, that is, a primary period $P_1=82.188{\pm}0.013h$ and a secondary period $P_2=67.13{\pm}0.20h$ are identified from period searches of its R band light curve. The light curve phases with $P_1$ and this indicate that it is a typical Non-Principal Axis (NPA) asteroid. We discuss the possible causes of its NPA rotation.

• 한국ITS학회 논문지
• /
• 제7권2호
• /
• pp.100-109
• /
• 2008

야간 교통사고는 도로 조명이 적절하지 못할 때 증가되는 경향이 있고, 차량이 도로 밖으로 이탈하는 사고는 시선유도 시설의 부재로 인한 대표적인 사고의 유형이라 할 수 있다. 곡선부의 교통사고와 인적피해를 줄이기 위해 운전자의 안전운행을 유도하고 교통소통 증진과 도로상의 안전을 도모하는 도로안전시설의 설치가 시급한 실정이다. 이에 교통량이 상대적으로 적은 지방부 도로에 대한 도로조명 설치와 같은 과다한 지출을 줄이고 오히려 비용 절감효과는 물론 시설물 설치가 용이한 시선유도시설(Delineators)의 설치기준이 요구되어진다. 곡선부에서 운전자의 시선을 유도하기 위한 시설은 시선유도표지(Delineator), 갈매기표지(Chevron Alignment Sign), 표지병(Raised Pavement Marker)이 널리 사용되고 있다. 본 연구에서는 곡선부의 선형 변화에 대한 정보를 가장 효율적으로 전달하는 시설물인 갈매기표지와 차량의 차로이탈 및 차로침범 예방시설물인 표지병을 대상으로 설치기준에 대해 검토하고 운전자의 시각행태 및 차로침범을 고려하여 안전하고 효율적인 설치기준을 제시하였다.

• 한국안광학회지
• /
• 제11권2호
• /
• pp.99-107
• /
• 2006

본 연구의 목적은 기초화장품에 노출된 소프트콘택트렌즈를 착용하였을 때 나타나는 불편감의 원인을 밝히는 것이다. 소프트콘택트렌즈를 스킨로션, 에센스로션 또는 영양크림에 노출 후 다시 7일간 인공누액에 노출하여 부착된 단백질 양, 가시광선 투과도, 습윤성 및 곡률반경의 변화를 측정하였다. 소프트콘택트렌즈에 부착된 단백질 양은 기초화장품의 노출에 의해 약 3배 증가하였다. 또한 영양크림과 인공누액 모두에 노출된 소프트콘택트렌즈의 가시광선 투과도는 92.8%로 인공누액에만 노출된 소프트콘택트렌즈의 97.5%보다 4.7% 더 낮았다. 스킨로션, 에센스로션, 영양크림에 노출됨에 따라 렌즈의 접촉각은 각각 $7.1^{\circ}$, $7.0^{\circ}$, $5.7^{\circ}$가 증가하였으며, 소프트콘택트렌즈의 곡률반경은 각각, 3.2%, 5.1% 및 8.3% 더 감소하였다.

• 천문학회지
• /
• 제52권5호
• /
• pp.181-205
• /
• 2019

There is evidence that the luminosities of Type Ia supernova (SN Ia) depend on their environments. While the impact of this trend on estimating cosmological parameters is widely acknowledged, the origin of this correlation is still under debate. In order to explore this problem, we first construct the YONSEI (YOnsei Nearby Supernova Evolution Investigation) SN catalog. The catalog consists of 1231 spectroscopically confirmed SNe Ia over a wide redshift range (0.01 < z < 1.37) from various SN surveys and includes light-curve fit data from two independent light-curve fitters, SALT2 and MLCS2k2. For a sample of 674 host galaxies, we use the stellar mass and the star formation rate data in Kim et al. (2018). We find that SNe Ia in low-mass and star-forming host galaxies are $0.062{\pm}0.009mag$ and $0.057{\pm}0.010mag$ fainter than those in high-mass and passive hosts, after light-curve corrections with SALT2 and MLCS2k2, respectively. When only local environments of SNe Ia (e.g., locally star-forming and locally passive) are considered, this luminosity difference increases to $0.081{\pm}0.018mag$ for SALT2 and $0.072{\pm}0.018mag$ for MLCS2k2. Considering the significant difference in the mean stellar population age between the two environments, this result suggests that the luminosity evolution of SNe Ia with redshift is most likely the origin of the environmental dependence.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 1992년도 한국우주과학회보 제1권1호
• /
• pp.14-14
• /
• 1992

The IUE archival spectra of VV Cephei were collected to investigate the eclipse nature in the ultraviolet. The temperature of the B star has been determined, as approximately30,OOOK, based en the flux distributions durstributions during egress, Light curves of VV Cephei were reduced from the spectrophotometry of the IUE archival spectra. Three light curves at the center wavelengths of 2350A,2550A and :!850A have been analyzed by the modified Wilson and Oevinney light curve program. the radii of the B star and M star were deduced to 0.05 and 0.22 of uint separation, respectively. The UV light curves show anevidence that the light was attenuated by the highly opaque atmosphere of the M star

• 천문학회보
• /
• 제35권1호
• /
• pp.50.1-50.1
• /
• 2010

We have analyzed times of minima for of 6 binary systems. Three binary systems show period decrease at rate $3.19{\times}10-5$ yr -1 for SV Cen, $1.35{\times}10-7$ yr -1 for RT Scl and $1.14{\times}10-7$ yr -1 for AD Phe. Two systems show period increase $5.696{\times}10-8$ yr -1 for SX Aur and $6.93{\times}10-8$ yr -1 for GO Cyg. One system shows cyclic period variation. We estimated the mass transfer rate for 5 binary systems. Four systems show asymmetric light curves. Two asymmetric light curves (SV Cen and RT Scl) are due to hot spot caused by mass transfer. And two asymmetric light curves (AD Phe and TY Boo) are due to cool spot caused by magnetic activities on the cooler component. We also obtain absolute dimensions from photometric solution and spectroscopic solution by analyzing their light curves and radial velocity curves, which are collected from literatures, using 2007 version Wilson and Deviney computer code.

• Journal of the Optical Society of Korea
• /
• 제16권2호
• /
• pp.107-114
• /
• 2012

In this paper, we propose a new modulation scheme called multi-coded variable pulse position modulation (MC-VPPM) for visible light communication systems. Two groups of signals (Pulse Width Modulation (PWM) and Pulse Position Modulation (PPM) groups) are multi-coded by orthogonal codes for transmitting data simultaneously. Then, each multi-level value of the multi-coded signal is converted to pulse width and position which results in not only an improved data rate, but also a processing gain in reception. In addition, we introduce average duty ratio and cyclic shift concepts in PWM through which dimming control for light illumination can be supported without any degradation in communication performance. Through simulation, we confirm that the proposed MC-VPPM shows a comparable BER curve and much greater achievable data rate than the conventional VPPM scheme using a visible light optical channel environment.

• Journal of Astronomy and Space Sciences
• /
• 제10권1호
• /
• pp.36-43
• /
• 1993

쵠근 발견된 식쌍성인 SAO23229에 대한 광전측광 관측을 소백산 천문대에서 수행하여 UBV 광도곡선을 얻고, 제 1 극심시각을 구하였으며, $O^p.75$부근에서 이상 변광현상을 발견하였다. 결정된 제1극심 시각은 HJD2448636.1170 $\pm$ 0.0005로 예측보다 3분 늦게 일어났으며, $O^p.75$에서의 변광은 식에 의한 것이 아니며 따라서 공전주기는 4.2일이라고 생각된다. 광도곡선을 분석하여 이 쌍성이 물리적 특성이 서로 같은 두 개의 F형 주계열성으로 이루어진 분리형 쌍성임을 밝혔다.

• Journal of Astronomy and Space Sciences
• /
• 제9권1호
• /
• pp.111-119
• /
• 1992

The IUE archival spectra of VV Cephei were collected to investigate the eclipse nature in the ultraviolet. The temperature of the B star has been determined, as approximately 30000K, based on the flux distributions during egress. Light curves of VV Cephei were reduced from the spectrophotometry of the IUE archival spectra. Three light curves at the center wavelengths of 2350 ${\AA}$, 2550 ${\AA}$ and 2850 ${\AA}$ have been analyzed by the modified Wilson and Devinney light curve program. The radii of the B star and M star were deduced to 0.05 and 0.22 of unit separation, respectively. The UV light curves show an evidence that the light was attenuated by the highly opaque atmosphere of the M star.