• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.117-126
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• 2011

RSA-CRT algorithm is widely used to improve the performance of RSA algorithm. However, it is also vulnerable to side channel attacks like as general RSA. One of the power attacks on RSA-CRT, proposed by Boer et al., is a power analysis which utilizes reduction steps of RSA-CRT algorithm with equidistant chosen messages, called as ECMPA(Equidistant Chosen Messages Power Analysis) or MRED(Modular Reduction on Equidistant Data) analysis. This method is to find reduction output value r=xmodp which has the same equidistant patterns as equidistant messages. One can easily compute secret prime p from exposure of r. However, the result of analysis from a reduction step in [5] is remarkably different in our experiment from what Boer expected in [5]. Especially, we found that there are Ghost key patterns depending on the selection of attack bits and selected reduction algorithms. Thus, in this paper we propose several Ghost key patterns unknown to us until now, then we suggest enhanced and detailed analyzing methods.

• Korean Business Review
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• v.17 no.2
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• pp.41-61
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• 2004

Before 2003 the companies in Korea should capitalize the interest expenses that are attributable to the acquisition, construction or production of a qualifying assets. However, according to the revised standard which should be applied from 2003, the companies can either capitalize the interest expenses or recognize as an expense when they are incurred. Therefore almost all the companies confronted with the decision making of accounting choices on the interest capitalization. This paper empirically examines which financial characteristics of the companies affect the accounting choice by using logistic regression model and reviews the sufficiency of the foot notes disclosures regarding the capitalized interest. The variables of the financial characteristics are change of debt-equity ratio, borrowing ratio, qualifying assets ratio, firm size and income smoothing. The results of this study are summarized as follows. First, among the financial characteristics, only qualifying asset ratio has the significant difference between capitalized companies and expensing companies. Second, the results of logistic regression indicate that qualifying asset ratio and firm size have the significant influence on the accounting choices. Therefore, I cannot find the evidence supporting that the companies use the accounting choice to manage the financial ratios.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.5
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• pp.1013-1022
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• 2014

Correlation Power Analysis (CPA) is a type of Side-Channel Analysis (SCA) that extracts the secret key using the correlation coefficient both side-channel information leakage by cryptography device and intermediate value of algorithms. Attack performance of the CPA is affected by noise and temporal synchronization of power consumption leaked. In the recent years, various researches about the signal processing have been presented to improve the performance of power analysis. Among these signal processing techniques, compression techniques of the signal based on Principal Component Analysis (PCA) has been presented. Selection of the principal components is an important issue in signal compression based on PCA. Because selection of the principal component will affect the performance of the analysis. In this paper, we present a method of selecting the principal component by using the correlation of the principal components and the power consumption is high and a CPA technique based on the principal component that utilizes the feature that the principal component has different. Also, we prove the performance of our method by carrying out the experiment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.6
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• pp.1103-1116
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• 2014

Collision attacks using side channel analysis confirm same intermediate value and restore sensitive data of algorithm using this point. In CHES 2011 Clavier and other authors implemented the improved attack using Blacklist so they carried out the attack successfully using less plaintext than before. However they did not refer the details of Blacklist method and just performed algorithms with the number of used plaintext. Therefore in this paper, we propose the specific method to carry out efficient collision attack. At first we define basic concepts, terms, and notations. And using these, we propose various methods. Also we describe facts that greatly influence on attack performance in priority, and then we try to improve the performance of this attack by analyzing the algorithm and structuring more efficient one.

• The Korean Journal of Financial Studies
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• v.6 no.1
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• pp.1-22
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• 2000

본 연구는 기업의 자본조달행태를 가장 잘 설명할 수 있는 이론을 자본조달순서 이론으로 대별하고 한국기업의 자본조달행동에 대한 설명력을 실증분석하였다. 실증분석결과는 첫째, 투자안에 소요되는 충분한 여유자금의 유무는 외부자본조달결정에 정(+)의 영향을 미치고 있으며, 보통주보다 회사채를 선호하는 것으로 나타났다. 그러나 현금과잉이 외부금융가능성에 음(-)의 영향을 미친다고 단정지을 수는 없다. 둘째, 기업의 위험이 증가할수록 부채사용의 증가를 예측하고 있으며, 정보비대칭에 관한 대용변수가 POT에서 주장하는 자본조달 신호로 작용하고 있지 않다. 이러한 결과는 투자안에 소요되는 내부자본이 부족하여 외부자본을 조달할 경우에 기업의 능력보다도 자본시장의 환경과 시장여건이 더욱 중요하다는 것을 시사하고 있다.

• Korean Journal of Rural Living Science
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• v.10 no.2
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• pp.1-14
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• 1999

The purposes of this study are to identify the factors affecting asset and debt choice behavior of rural households as well as to examine the differences in asset and debt choice behavior between rural and urban households. The data are taken from Korean Household Panel Study conducted in 1996 by Daewoo Economic Research Institute. Among 2,833, a final sample of 2,625 -537 rural and 2,088 urban sample- is used in this study. The results show that, the asset and debt choice behavior of rural households is totally different from that of urban households. The ratio of rural households holding all types of financial assets and sales credit is less than that of urban households while the ratio of holding real asset and loan is greater in rural than urban households. The most influential variable on the ownership of asset and debt is the age of household head. And there exist interrelationships between ownership of different assets and debts.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.518-526
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• 2017

This study analyzed the impact of family firms and their characteristics on how they use debts to analyze the decision-making process of Korean family firms. For analysis, we classified the characteristics of family firms into three categories, through the influence of the relationship between the lack of funds and net debt issuance, which was confirmed as the 'packing order theory' of family firms. There was a total of 4,503 enterprises in the Korean Exchange (KRX). The period of analysis was 10 years, between 2004 and 2014. To summarize, Shyam-Sunder and Myers (1999) validated the packing order theory by presenting a model of family businesses that showed greater applicable to higher packing order theory than a model of non-family businesses. Moreover, the results also confirmed the application of the packing order theory by the family stronger corporate governance and ownership structure. The ownership and governance characteristics of the ruling family has also shown the applicability of higher packing order theory.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1300-1310
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• 2003

In this paper, the performance of a multicarrier CDMA system using adaptive modulation and adaptive subchannel allocation scheme is analyzed in Rayleigh fading channel. The proposed adaptive modulator consists of modulation schemes using QPSK 16 QAM, 64 QAM and 256 QAM and constellations are pointed by Gray code. In addition, the threshold of the analysis is average E$\_$b//N$\_$o/ when the BER is 1 %. In the multicarrier system with adaptive subchannel allocation scheme, each DS waveform of user is transmitted over the K subchannels with the biggest fading among L subchannels. In case of the proposed system, total 4 subchannels are used and data are transmitted over 2 subchannels with the biggest fading, which results in the threshold of each channels is 5.2 dB, 9 dB, 13.2 dB and 8.4 dB, 12.2 dB, 16.3 dB. In the case of proposed system, the BER of 10$\^$-3/ is satisfied if average E$\_$b//N$\_$o/ is 8.1 dB. This is increased performance of 12.9 dB in comparison with conventional system. The BPS according to average channel is needed average E$\_$b//N$\_$o/ of about 15 dB in 7 bit. In the case of subchannel error, the BER of 10$\^$-3/ is 13.6 dB and is declined about 5.5 dB.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.5
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• pp.1001-1011
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• 2017

A lattice-based cryptography is known as one of the post-quantum cryptographies. Ring-LWE problem is an algebraic variant of LWE, which operates over elements of polynomial rings instead of vectors. It is already known that post-quantum cryptography has side-channel analysis vulnerability. In 2016, Park et al. reported a SPA vulnerability of the public key cryptosystem, which is proposed by Roy et al., based on the ring-LWE problem. In 2015 and 2016, Reparaz et al. proposed DPA attack and countermeasures against Roy cryptosystem. In this paper, we show that the chosen ciphertext SPA attack is also possible for Lyubashevsky cryptosystem which does not use NTT. And then we propose a countermeasure against CCSPA(Chosen Ciphertext SPA) attack and we also show through experiment that our proposed countermeasure is secure.

• Korean small business review
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• v.41 no.2
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• pp.51-78
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• 2019

The purpose of this study is to classify unlisted companies' entering method into stock market and to find out a advantageous choice between IPO and SPAC. The research samples are two types(79 IPO companies and 46 SPAC companies) of 125 companies. Which were being listed in the KOSDAQ market from 2010 to 2017. The analysis results are as follows. At first, after analyzing the impact of well known variables such as asset size, company history and number of employees to select listing methods. I found that the variables of asset size and company history have a significant negative (-) effect on the SPAC variable. Secondly, the debt ratio variable has a significant positive (+) effect on the SPAC variable. Third, it was found that the ratio of profitability variables, such as operating income to sales have a systematically positive (+) effect on the SPAC variable. Fourth, I analyzed the impact of the largest stockholder in unlisted companies on the selection of listing methods. I found that the largest stockholder are systematically having a positive (+) effect on SPAC. The result means that unlisted companies that chose SPAC have the larger shareholder shares that are relatively higher than the unlisted companies that chose IPO.