• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.8
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• pp.2157-2169
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• 2023

In order to handle the problem that puncture patterns will change the position distribution of original information bits and frozen bits in polar codes, which affects performance of puncture polar codes further, a minimum row weight and polar spectrum based puncture polar codes construction algorithm (called PA-MRWP) is proposed in this paper. The algorithm calculates row weight of generator matrix and sorts the row weight in ascending order first. Next, the positions with the minimum row weight are selected as initial puncture positions. If the rows with the same row weight cannot all be punctured, polar spectrum based auxiliary puncture scheme is used. In sub-channels with the same row weight, rows corresponding to the polarized sub-channels with higher reliability are selected as puncture positions to construct puncture vector, and the reliability is calculated based on polar spectrum. It is actually a two-step selection strategy, the proposed minimum row weight puncture (MRWP) algorithm is used for primary selection and polar spectrum based auxiliary puncture is used for adjustment. Simulation results show that, compared with worst quality puncture (WQP) algorithm, the proposed PA-MRWP algorithm and Gaussian approximation-aided minimum row weight puncture (GA-MRWP) algorithm provide gains of about 0.46 dB and 0.29 dB at bit error rate (BER) of 10^-4, respectively when code length N=400, code rate R=1/2. In addition, the proposed puncture algorithms improve the BER performance significantly with respect to quasi-uniform puncture (QUP) algorithm.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.178-188
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• 1996

In this paper, we propose a new opto-digital object recognition system which has rotation, scale, and shift invariant characteristics. The fourier power spectrum of the object image is modified to get shift invariance. The log-polar transform is used for rotation and scale invariance. And the decision of similarities is performed by nonlinear joint transform correlator (NJTC) that can control the ratio of phase and amplitude signals. Experimental verification of th eproposed optical object recognition system is presented.

• International journal of advanced smart convergence
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• v.10 no.4
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• pp.45-51
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• 2021

Polar transmitter can support multi-band and multi-mode operation. The efficiency of frequency usage can be increased if polar transmitters can transmit multi-carrier signals. In this paper the configuration of polar transmitters is investigated to generate multi-carrier signals. Spectrum and CCDF Simulation results of two-carrier signals generated by the polar transmitter can be used to design of PM and AM path in a polar transmitter.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.55-59
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• 2014

Multi-band and multi-mode transmitters are needed for SDR and CR. Recently many types of polar transmitters have been studied in order to implement a multi-band and multi-mode transmitter. Polar transmitters have many advantages, such as a simple structure, high efficiency and etc. In this paper we consider the number of D/A bit and the effects of a delay mismatch as design parameters for implementing polar transmitters. From the simulation we know that a 10 bit D/A is sufficient and a delay mismatch must be maintained small than 1/64 chip for satisfying the spectrum mask characteristics. We implement a polar transmitter based on the design parameters and the measured output signal meet the spectrum mask of 800MHz CDMA.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.22.1-22.1
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• 2011

Two dominant components of polar motion are the Chandler and the annual components. Recently, the existence of 500-day period component in the Earth's polar motion has been manifested. But its existence is not clear on Fourier spectrum. One cause of difficulty involved here is that the amplitudes of the two main components are slightly variable in time by certain amounts (Chandler: 0.15~0.28 arcsec, annual: 0.09~0.15 arcsec). A residual polar motion time series excluding the two main components for a time span between 1962 Jan and 2010 Nov from IERS C04 time series dataset was constructed by least square fitting. For faithful fitting, 43 time segments of 6.8 year length (each starts on January 1st of successive years) were separately acquired and later combined together. The period of dominant peak in the spectrum of this residual polar motion time series is 490 days. Next peaks have their periods as semi-annual, 300~330 days, ~560 days, 670 days, and 1360 days.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.10
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• pp.12-21
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• 1998

A chaotic spread spectrum communication system using a polar quarternary method is designed and implemented. Four different chaotic signals in the relation of multiplication each other are generated through the use of a coupled synchronization method in the transmitter which is composed of four Chua's circuits. Information is retrieved at the receiver which is connected to the transmitter through the use of a drive synchronization method. Since spread spectrum of information signal is spread by chaotic signal, the configuration of the system is simpler than that of any other conventional system.

• Korean Journal of Remote Sensing
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• v.34 no.4
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• pp.649-659
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• 2018

The aim of this study is to develop a protocol for obtaining spectral signals that are robust to varying lighting conditions, which are often found in the Polar regions, for creating a spectral library specific to those regions. Because hyperspectral image (HSI)-derived spectra are collected on the same scale as images, they can be directly associated with image data. However, it is challenging to find precise and robust spectra that can be used for a spectral library from images taken under different lighting conditions. Hence, this study proposes a new radiometric calibration protocol that incorporates radiometric targets with a traditional vicarious calibration approach to solve issues in image-based spectrum measurements. HSIs obtained by the proposed method under different illumination levels are visually uniform and do not include any artifacts such as stripes or random noise. The extracted spectra capture spectral characteristics such as reflectance curve shapes and absorption features better than those that have not been calibrated. The results are also validated quantitatively. The calibrated spectra are shown to be very robust to varying lighting conditions and hence are suitable for a spectral library specific to the Polar regions.

• Journal of Astronomy and Space Sciences
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• v.11 no.1
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• pp.1-12
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• 1994

The structure of the magnetic funnel element in the intermediate polar is considered in terms of an important site for the X-ray absorption and the reemission of the X-ray as the optical light. In this paper the column density and the optical depth vary with the filling factor, which is introduced to characterize the structure of matter in the magnetic funnel element. The results of the energy dependence of the X-ray spectrum and the modulation depth of the X-ray light curve are discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.317-323
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• 2011

We use the finite element method to analyze the seismic design of a liquid storage tank for a polar crane at a nuclear power plant. We obtained the natural frequency and vibration modes by modal analysis, and we evaluated the seismic stability by response spectrum analysis. Furthermore, the seismic analysis of the tank was accomplished by analyzing not only the forces applied to the wall by the sloshing of the liquid, but also the safe-shutdown earthquake condition for the tank. We propose a seismic-design process and a seismic-analysis method for liquid storage tanks based on the commercial finite element analysis program, ANSYS.

• The Pure and Applied Mathematics
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• v.5 no.2
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• pp.109-114
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• 1998

Let H be a separable complex H be a space and let (equation omitted)(H) be the *-algebra of all bounded linear operators on H. An operator T in (equation omitted)(H) is said to be p-hyponormal if ($T^{\ast}T)^p - (TT^{\ast})^{p}\geq$ 0 for 0 ＜ p ＜ 1. If p = 1, T is hyponormal and if p = $\frac{1}{2}$, T is semi-hyponormal. In this paper, by using a technique introduced by S. K. Berberian, we show that the approximate point spectrum $\sigma_{\alpha p}(T) of a pure p-hyponormal operator T is empty, and obtains the compact perturbation of T.