• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.1
• /
• pp.55.2-56
• /
• 2021

The progenitor of Type Ia supernovae (SNe Ia) is mainly believed to be a close binary system of acarbon-oxygen white dwarf (CO WD) and non-degenerate companion (single degenerate) or another WD (double degenerate). However, it is unclear which system is more prevalent. Here, we present a high cadence optical/Near-IR light curve of normal but slightly faint type Ia SN 2019ein from IMSNG project. We fit the early light curve (t <+8.3 days from the first detection) with various models to find the shock-heated cooling emission from SN ejecta-companion interaction. No significant shock-heated cooling emission is found, from which we constrain the progenitor star size as the following. The upper limit (R_upper,*) of the companion size in R-band is ~0.2R_⊙ when forcing the first light time (t_fl) to have one value and ~0.9R_⊙ when using the mean value of tfl from the fitting in each band. Assuming the source of the I-band curve is almost powered from the radioactive decay, we obtained R_upper,*~1.2R_⊙. The early B-V color curve is in agreement with the model color curve of the 2M_⊙ main sequence companion. These results allow us to at least rule out large stars like red giants as a companion star of the binary progenitor system of this supernova. B-R and V-R color do not show any significant signs of a red bump, which shows a thin helium shell (MHe<0.1M_⊙) for the sub-Mch WD (double detonation model). In addition, we estimated the distance to NGC 5353 as 37.098±0.028Mpc.

• Corrosion Science and Technology
• /
• v.18 no.6
• /
• pp.243-252
• /
• 2019

The pitting corrosion and inhibition studies of AZ31B magnesium alloy were investigated in the alkaline solution (pH12) with chloride and inhibitors. The corrosion behavior of passive film with/without Cl^- in the alkaline electrolyte were conducted by polarization curve and immersion tests in the presence of various additives (inhibitors) to clarify the inhibition efficiency of pitting corrosion at higher potential region. Critical concentration of pitting corrosion for Mg alloy was evaluated with 0.005 M NaCl in 0.01 M NaOH on the anodic polarization behavior. Critical pitting of AZ31B Mg alloy in 0.01 M NaOH is a function of chlorides; E_pit = - 1.36 - 0.2 log [Cl^-]. When the Sodium Benzoate (SB) was only used as an inhibitor, a few metastable pits developed on the Mg surface by an immersion test despite no pitting corrosion on the polarization curve meaning that adsorption of SB on the surface is insufficient protection from pitting corrosion in the presence of chloride. The role of SB and Sodium Dodecylbenzenesulfonate (SDBS) inhibitors for the Mg alloy surface in the presence of chloride was suppressed from pitting corrosion to co-adsorb on the Mg alloy surface with strong formation of passive film preventing pitting corrosion.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.10a
• /
• pp.386-389
• /
• 2008

Forming limit diagram is created by graphical illustration indicating major and minor strain. In order to provide the criterion for forming safety, FLC(forming limit curve) need to be fitted to the diagram. However, the standard method for the strain measurement and FLC plotting are not fixed yet, which results in inconvenience in digitalized analysis. In this study, new construction method for FLC was suggested in order to minimize operator dependency. For this purpose, major and minor strain were measured automatically and analyzed. Then, a second order equation is adopted to fit the FLC. Optimized by response surface method was performed to ensure particular characteristics of the FLC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.12S
• /
• pp.1305-1309
• /
• 2003

To utilize FeCoSiB amorphous films for magnetoelastic sensors, the temperature dependency of magnetization (M-T curve) and the magnetization properties of the amorphous films were investigated in this study. As the amount of cobalt In the films increased, the Curie temperature decreased but the crystallization temperature increased. In addition to this, the crystallization temperature was lower than the Curie temperature in the film containing 20 at% cobalt. The optimized annealing condition was set up by analyzing the H-T curve. And then, the amorphous film that has excellent magnetic properties and uni-axal anisotropy could be prepared for construction of the magnetoelastic sensor devices. The coercive force of the film was below 0.5 Oe and the anisotripic field was about 5 Oe.

• Korean Journal of Veterinary Research
• /
• v.50 no.1
• /
• pp.11-17
• /
• 2010

Linear and non-linear regressions were used to derive the calibration function for the measurement of roxithromycin plasma concentration. Their results were compared with weighted least squares regression by usual weight factors. In this paper the performance of a non-linear calibration equation with the capacity to account empirically for the curvature, y = ax$^{b}$ + c (b $\neq$ 1) is compared with the commonly used linear equation, y = ax + b, as well as the quadratic equation, y = ax$^{2}$+ bx + c. In the calibration curve (range of 0.01 to 10 ${\mu}g/mL$) of roxithromycin, both heteroscedasticity and nonlinearity were present therefore linear least squares regression methods could result in large errors in the determination of roxithromycin concentration. By the non-linear and weighted least squares regression, the accuracy of the analytical method was improved at the lower end of the calibration curve. This study suggests that the non-linear calibration equation should be considered when a curve is required to be fitted to low dose calibration data which exhibit slight curvature.

• Journal of the Korea Society of Computer and Information
• /
• v.27 no.5
• /
• pp.181-188
• /
• 2022

In this paper, we proposed of the results of the noise level and appropriate conversation distance by applying the noise characteristics generated during treatment at a dental clinic to the NR-curve and PSIL. As a result of analyzing the noise characteristics during treatment at a dental clinic, it was analyzed that the noise level exceeded 60dB(A), which is the health preservation limit value caused by noise, and the noise level increased as the frequency increased. the result of evaluation applying it to the NR curve, some treatment exceeded the workplace noise standard, and as a result of analyzing the level of conversational disturbance between the worker and the patient, it is desirable to have the conversation at a distance of less than 1M for accurate communication. In order to improve the quality of medical service in dental clinic and to reduce dental fear, it is judged that soundproofing protective equipment is provided to workers, and soundproofing measures are needed for noise sources (treatment devices used in treatment) and sound sources (patients and workers).

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.627-628
• /
• 2008

• The Pure and Applied Mathematics
• /
• v.14 no.4
• /
• pp.231-253
• /
• 2007

The purpose of this paper is to study the geometry of null curves in a semi-Riemannian manifold (M, g) of index 2. We show that it is possible to construct new Frenet equations of two types of null curves in M.

• The Pure and Applied Mathematics
• /
• v.12 no.3 s.29
• /
• pp.211-221
• /
• 2005

The purpose of this paper is to study the geometry of null curves in a Lorentzian manifold (M, g). We show that it is possible to construct new type of Frenet equations of null curves in M, supported by two examples.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.169-170
• /
• 2018

이진체 상의 타원곡선 B-233을 지원하는 타원곡선 암호 프로세서를 32-비트 워드기반 몽고메리 곱셈기를 이용하여 설계하였다. 스칼라 곱셈을 위해 수정된 몽고메리 래더 (Modified montgomery ladder) 알고리즘을 적용하여 단순 전력분석에 내성을 갖도록 하였으며, Lopez-Dahab 투영 좌표계와 페르마의 소정리(Fermat's little theorem)를 적용하여 하드웨어 자원 소모가 큰 나눗셈과 역원 연산을 제거하여 저면적으로 설계하였다. 설계된 ECC 프로세서는 Xilinx ISim을 이용하여 기능검증을 하였으며, $0.18{\mu}m$ CMOS 셀 라이브러리로 합성한 결과 100 MHz의 동작 주파수에서 9,614 GEs와 4 Kbit RAM으로 구현되었으며, 최대 동작 주파수는 125 MHz로 예측되었다.