• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.11
• /
• pp.1448-1454
• /
• 2018

In an optical observing system, three pairs of observations at equal time intervals are required for the orbit determination method to obtain orbital information of an unknown space objects. In this paper, we propose a method of estimating a streak for acquiring three pairs of observations using one streak image information. Satellite trajectory simulation data were generated for nine cases using the STK program in order to verify the characteristics of the orbit of space object and estimation performance. Simulation was performed by applying three approaches that can estimate the next streak position after a few seconds from one streak image information, and the estimation performance was evaluated. Linear vector method and Kalman Filter method based on the linear assumption tend to increase the estimation error in the region where the nonlinearity is large. However estimation method using the polynomial curve fitting based on the least square method showed smaller and uniform error result than the previous methods.

• Journal of the Korean Society for Railway
• /
• v.10 no.5
• /
• pp.506-510
• /
• 2007

Smoke temperature and volume flow rate in a tunnel fire are calculated. To obtain realistic results, enthalpy of smoke which composites combustion gases and entrainment air is calculated from curvefit polynomials by temperature. A user-friendly computer program for them is also developed. This program might be used for a good engineering tool in design of fire safety and mock/reduced-scale fire tests in a tunnel.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.2
• /
• pp.131-138
• /
• 2016

In this paper, we studied the IRF performances of the chirp signal used in the SAR system. The most important factors that degrade IRF performances are amplitude and phase errors. Each factor can be represented to linear, quadratic, random and ripple terms. That can be extracted by a quadratic polynomial curve fitting of chirp waveform. We analyzed the IRF performances by the error terms and supposed the minimum value of RF non-linearity to meet the specification of the PSLR and ISLR.