• The Mathematical Education
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• v.22 no.1
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• pp.77-79
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• 1983

• Communications of the Korean Mathematical Society
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• v.2 no.1
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• pp.53-57
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• 1987

• Korean Architects
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• s.616
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• pp.142-147
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• 2020

• Journal for History of Mathematics
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• v.27 no.4
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• pp.259-269
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• 2014

In China and Joseon, the measurement of the areas of various plane figures is a very important subject for mathematical officials because it is connected directly with tax problems. Most of mathematical texts in China and Joseon contained Chinese character '田', which means a field for farming, in title name for parts that dealt with problems of areas and treated as areas of plane figures. The form of mathematical texts in Joseon is identical with those in China because mathematicians in Joseon referred to texts in China. Gyeong SeonJing and Hong JeongHa also referred to Chinese texts. But they added their interpretations or investigated new methods for the measurement of areas. In this paper, we investigate the history of the measurement of areas in Joseon, which described in two books MukSaJibSanBeob and GuIlJib, with comparing some mathematical texts in China.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.2
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• pp.524-539
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• 2014

To investigate schemes of secret key generation from Ultra-wideband (UWB) channel, we study a statistical characterization of UWB outdoor channel for a campus playground scenario based on extensive measurements. Moreover, an efficient secret key generation mechanism exploiting multipath relative delay is developed, and verification of this algorithm is conducted in UWB Line-of-sight (LOS) outdoor channels. For the first time, we compare key-mismatch probability of UWB indoor and outdoor environments. Simulation results demonstrate that the number of multipath proportionally affects key generation rate and key-mismatch probability. In comparison to the conventional method using received signal strength (RSS) as a common random source, our mechanism achieves better performance in terms of common secret bit generation. Simultaneously, security analysis indicates that the proposed scheme can still guarantee security even in the sparse outdoor physical environment free of many reflectors.

• ETRI Journal
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• v.29 no.3
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• pp.381-389
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• 2007

In this paper we propose a graph-theoretic method based on linear congruence for constructing low-density parity check (LDPC) codes. In this method, we design a connection graph with three kinds of special paths to ensure that the Tanner graph of the parity check matrix mapped from the connection graph is without short cycles. The new construction method results in a class of (3, ${\rho}$)-regular quasi-cyclic LDPC codes with a girth of 12. Based on the structure of the parity check matrix, the lower bound on the minimum distance of the codes is found. The simulation studies of several proposed LDPC codes demonstrate powerful bit-error-rate performance with iterative decoding in additive white Gaussian noise channels.

• Asian Journal for Public Opinion Research
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• v.3 no.2
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• pp.84-105
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• 2016

The instability of social norms on the Internet causes the diversity of social identification. Meanwhile, the anonymity of online social identity and the chaos of the role-playing among the interacting participants cause an ambiguity of identity recognition, which intensifies anxiety about interpersonal interaction. Methods that promote face-to-face interpersonal interaction through the reconstruction of the identification to the social system and intergroup trust is worth further research. Based on a telephone survey of urban residents in thirty-six cities in China (N=1080), the study focuses on the influence of Internet use on interpersonal interaction of urban residents and the mediation effect of social identification. The results show that Internet use has a negative effect on the interpersonal interactions of urban residents, and social identification plays a mediating effect between Internet use and interpersonal interaction. Implications of the results are discussed.

• Journal for History of Mathematics
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• v.26 no.4
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• pp.213-218
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• 2013

This paper is a sequel to the paper [8], where we discussed the connection between ShiShou KaiFangFa originated from JiuZhang SuanShu and ZengCheng KaiFangFa. Investigating KaiFangShu in a Chosun mathemtics book, SanHak JeongEui and ShuLi JingYun, we show that its authors, Nam ByungGil and Lee SangHyuk clearly understood the connection and gave examples to show that the KaiFangShu in the latter is not exact. We also show that Chosun mathematicians were very much selective when they brought in Chinese mathematics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3557-3571
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• 2014

We develop a secret key generation scheme using phase estimation in ultra-wideband (UWB) wireless fading channels. Based on the reciprocity theorem, two terminals extract the phase of the channel as a common random source to generate secret bits. Moreover, we study the secret key rate by a pair of nodes observing correlated sources and communicating to achieve secret key agreement over public communication channels. As our main results, we establish a more practical upper bound from Cramer-Rao bound (CRB) and compare it with a universally theoretical upper bound on the shared maximum key rate from mutual information of correlated random sources. Derivation and numerical examples are presented to demonstrate the bound. Simulation studies are also provided to validate feasibility and efficiency of the proposed scheme.

• Mycobiology
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• v.40 no.4
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• pp.258-262
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• 2012

cDNA of the glx1 gene encoding glyoxal oxidase (GLX) from Phanerochaete chrysosporium was isolated and expressed in Pichia pastoris. The recombinant GLX (rGLX) produces $H_2O_2$ over 7.0 nmol/min/mL using methyl glyoxal as a substrate. Use of rGLX as a generator of $H_2O_2$ improved the coupled reaction with recombinant manganese peroxidase resulting in decolorization of malachite green up to $150{\mu}M$ within 90 min.