케일리 공식의 네 가지 증명

서승현,권석일,홍진곤,Seo, Seung-Hyun,Kwon, Seok-Il,Hong, Jin-Kon 한국수학사학회 2008 Journal for history of mathematics Vol.21 No.3

수학의 역사에서는 이미 발견되어 논증된 정리를 새로운 방법으로 공략함으로써 그 정리의 깊은 의미를 드러내는 작업의 기록을 쉽게 찾을 수 있다. 이 연구는 직관적으로 비교적 이해하기 쉬운 소재인 수형도를 대상으로 하여, 꼭지점의 집합이 결정되었을 때 수형도의 개수를 결정하여 주는 케일리 공식(Cayley formula)의 증명에 대한 서로 다른 네 가지 접근방법을 소개하는 것을 목적으로 한다. 네 가지 증명은 수형도의 성질로부터 유도된 재귀적 관계식을 이용한 케일리의 증명에서부터 특정한 수학적 대상과 수형도 사이의 일대일대응 관계에 주목하는 나머지 세 가지 증명으로 이루어진다. 특히, 마지막 증명은 순수한 수학적 작업이 다른 분야에 강력한 도구를 제공하는 전형적인 예를 보여준다. In this paper, we introduce four different approaches of proving Cayley formula, which counts the number of trees(acyclic connected simple graphs). The first proof was done by Cayley using recursive formulas. On the other hands the core idea of the other three proofs is the bijective method-find an one to one correspondence between the set of trees and a suitable family of combinatorial objects. Each of the three bijection gives its own generalization of Cayley formula. In particular, the last proof, done by Seo and Shin, has an application to computer science(theoretical computation), which is a typical example that pure mathematics supply powerful tools to other research fields.

OTP-EKE:원-타임-패스워드 기반의 키 고환 프로토콜

서승현,조태남,이상호,Seo, Seung-Hyun,Cho, Tae-Nam,Lee, Sang-Ho 한국정보과학회 2002 정보과학회논문지 : 시스템 및 이론 Vol.29 No.5

키 교환 프로토콜에서 상호 인증은 필수 요소이며, 사용자에게 편리하고 비용이 적게 드는 패스워드 기반의 인증 방식이 널리 사용되고 있다. 패스워드 기반의 프로토콜은 패스워드가 가지는 제약으로 인한 공격에 대해서 안전해야 할 뿐 아니라, 사용자의 작업량을 줄이기 위한 효율성도 매우 중요한 요건 이다. 본 논문에서는 서버와 사용자간의 인증을 제공하고 세션키를 공유하기 위한 키 교환 프로토콜 OTP-EKE(One Time Password based Encrypted Key Exchange)를 제안하였다. 키 교환을 위한 사용자 인증방식으로 패스워드 방식을 채택하였다. 특히 서버 디렉토리에 대한 공격 등에 대해서 안전도를 높이기 위하여 원-타임-패스워드 확인자와 서버의 공개 패스워드를 이용하였다. 제안한 프로토콜은 모듈라지수승 계산 횟수와 메시지 전송 횟수를 줄임으로써 효율성 향상을 보인다. Mutual authentication is essential for key exchange protocols and password-based authentication scheme is used widely, which is convenient to users and executed on the cheap. Password-based protocol should be not only secure against attach but also efficient to reduce user's load. In this paper, we propose a new key exchange protocol, called OTP-EKE(One Time Password based Encrypted Key Exchange), to provide authentication and to share a session key between a server and a user. We choose a password-based scheme as a user authentication. Especially, we use a one-time-password verifier and server's public password to protect against attacks on server's directory. As for efficiency, we improve the performance by reducing the number of modular exponentiations and the number of rounds.

스마트폰 보안 위협 및 대응 전략

서승현,전길수,Seo, Seung-Hyeon,Jeon, Gil-Su 한국정보통신기술협회 2010 TTA저널 Vol.132 No.-

성인지적 관점에서 본 러시아 이주여성의 문제와 정책과제

서승현(Seo Seung Hyun) 한국슬라브유라시아학회 2015 슬라브학보 Vol.30 No.2

The article is researched on gender perspective of migration policy in Russian society. Starting from a question about human rights and gender equality of women immigrant laborer. It is necessary to change the migration policy as a gender aspect for social integration in Russia. The patterns of international migration is impacted on Russian migration as a way to strength the globalization and the feminization of migration. In particular, Russian migration is showing to rise feminization of migration and Eurasian trend of migration from Central Asia. The purpose of this paper proves that international migration tendency leads to empower women"s right or gender inequality in Russia. And it also proves how to reflect this problems on the Russian migrant policy as the gender perspective. For this, first, this paper is to explore the international migration theories in the gender perspective. Second, the current status and situation of women immigrant to Russia from CIS. Third, this article is to study the Russian migration laborer"s problems, specially about women immigrant, based on the Russian theories and materials as a gender aspect. Nowadays the issue of social and gender inequality about women immigration became more severe. They were very often treated unfairly at work and on the social welfare in Russian society. Therefore, it is important to consider how women immigrant suffer from the norms of sexuality discrimination between migrant-sending and receiving countries. Recently Russian government announced a new migration policy. The government tried to accept more high quality human capital to Russia to find a solution about the depopulation in Russia. President Putin has put migrant policy reform at the important of his agendas. But it hasn"t considered as the migration policy about human rights and gender problems as ever. Because the Russian policy have to be reformed to way to rise the migration policy in the gender perspectives.

러시아와 한국 청장년층의 결혼과 가족 가치관의 비교사회학적 연구

서승현 ( Seung Hyun Seo ) 대구가톨릭대학교 사회과학연구소 2007 사회과학논총 Vol.6 No.-

Summary (resume) Subject: Comparative sociological research of young people`s point of view about marriage and family between Russian Federation and Republic Korea. Author`s name: SEO SEUNG HYUN In this paper is analyzing the different materials of first Russian-Korean comparative sociological research of direction among young people about marriage & family in the modern society. And there is analysis of the Korean and Russian family`s condition and perspective as a social institute, as a object of family policy in the structural-functionalism. Be made emphatic on the relations to family policy of respondents. More than that there was a special interest in the common opinion of young people of both countries in the gender aspect.

2010년 모바일 악성코드 동향 분석 및 전망

서승현(Seung-Hyun Seo),김종명(Jong-Myoung Kim),전길수(Kilsoo Chun) 한국정보보호학회 2011 情報保護學會誌 Vol.21 No.1

국내외 스마트폰 가입자 수의 폭발적인 증가는 스마트폰을 활용한 소셜미디어 산업, 생활 밀착형 어플리케이션 개발산업, 모바일 광고 및 미디어 산업 등 관련 산업의 활성화를 이끌고 있으며, 정부 및 민간 기업에서도 스마트폰을 활용한 모바일 오피스 도입에 관심을 기울이고 있다. 그러나 ‘손안의 PC’로 불리는 스마트폰은 기존 PC가 가지고 있던 보안 위협 문제들도 내재하고 있으면서 무선인터넷환경, OS 플랫폼의 개방성, 오픈마켓의 위험성, 도난 및 분실, 위치정보 노출 등의 신규 보안 위협도 존재하기 때문에 이런 취약성들을 활용한 새로운 모바일 악성코드들의 출현될 가능성이 더욱 커졌다. 따라서 본 논문에서는 현재까지 발생한 국내외 모바일 악성코드의 현황을 살펴보고, 2010년에 출현하였던 모바일 악성코드들의 주요 사례를 분석함으로써, 최근 악성코드들의 동향과 향후 전망에 대하여 기술하고자 한다.

양방향 인터리브드 DC/DC 컨버터의 수동소자 설계

서승현(S. H. Seo),김진걸(J. G. Kim) 한국정밀공학회 2015 한국정밀공학회 학술발표대회 논문집 Vol.2015 No.12월

러시아어 대용어(Anaphora)의 국부 영역(Local Domain)에 대하여

서승현(Seo Seung Hyun) 한국슬라브유라시아학회 2002 슬라브학보 Vol.17 No.2

Since Chomsky formulated the Binding Theory, the characteristically invariant form of anaphora in many languages provides a crucial link between morphology and binding. It has been argued that invariance reflects lack of those speculations for gender, number and person which enable pronouns to have independent reference. Unlike pronouns, anaphora must therefore always be bound because binding represent the conditions under which reference is inherited. Then, Burzio shows that the true cross-linguistic generalization for pronoun is complementary with anaphora, and not 'not locally bound' by Chomsky's principle B. In this article I examined how well or badly his proposals fit in Russian. As I have discussed above, Burzio's statement that an anaphor has no features, is too general and somewhat wrong in the view of Russian anaphora, because Russian reflexive possessive свой has distinct features depending on person, number and gender. He does not even mention case at all which Russian anaphora retain. Moreover, to the contrary of hierarchical order of choice for NPs by Burzio, the choice among NPs (anaphor, pronominal and R-expression), according to Timberlake, depends on the type of sentence, governing verb and so on. Lastly, not only do we need to give a different notions for principle A and B as Burzio argues, but also we need to verify local domains in dealing with Russian anaphora (reciprocal and reflexive). As shown above, therefore, the conditions of Russian anaphora are too various and delicate to simply generalize as Burzio does.

통합인증센터를 활용한 일회용 가상카드번호 생성 및 결제 서비스 프로토콜

서승현(Seung-Hyun Seo) 한국정보보호학회 2010 정보보호학회논문지 Vol.20 No.3

최근 유명 온라인 쇼핑몰 사이트가 해킹을 당해 많은 사용자들의 ID, 패스워드, 계좌번호, 주민등록번호, 신용카드번호와 같은 개인 정보들이 누출되었다. 해커들은 계속해서 온라인 쇼핑몰 사이트 에 대한 공격을 하고 있으며 해킹피해자들의 수도 증가하고 있다. 신용카드 번호가 누출되면, 해커들이 금전적인 이득을 취하기 위해 누출된 카드번호를 악용할 수 있어 특히 위험하다. 2007년 Financial Cryptography 학회에서 Ian Molly 등이 최초로 일회용 가상카드번호 생성 스킴을 제안한 바 있으나, 재사용불가의 특성을 제공하지 못한다. 본 논문에서는 Ian Molly 스킴의 취약성을 분석하고, 휴대단말기를 활용하여 일회용 가상카드번호의 보안요구사항을 만족하는 새로운 일회용 가상카드번호 생성 스킴을 제안하였다. 또한, 이를 기반으로 사용자 편의성과 보안성강화를 위해 통합인증센터를 활용한 일회용 가상카드 결제 프로토콜을 설계한다. Recently, famous online shopping websites were hit by hacking attack, and many users' personal information such as ID, password, account number, personal number, credit card number etc. were compromised. Hackers are continuing to attack online shopping websites, and the number of victims of these hacking is increasing. Especially, the exposure of credit card numbers is dangerous, because hackers maliciously use disclosed card numbers to gain money. In 2007 Financial Cryptography Conference, Ian Molly et al. firstly proposed dynamic card number generator, but it doesn't meet reuse resistant. In this paper, we analyzed security weaknesses of Ian Molly's scheme, and we proposed a new one-time virtual card number generator using a mobile device which meets security requirements of one-time virtual card numbers. Then, we propose one-time credit card number generation and transaction protocol using Integrated Authentication Center for user convenience and security enhancement.

러시아어 구어체에서의 뒤섞기(scrambling), 자질의 동질성 그리고 상대적 최소(Relativized Minimality)의 관계

서승현(Seo Seung Hyun) 한국노어노문학회 2003 노어노문학 Vol.15 No.2

Assuming free word order in Russian to be the result of applying the rule of scrambling (the adjunction option of Move-α, i. e., "adjoin any maximal projection to any maximal projection"), I intend to show that universal conditions properly restrict the output of this rule and make it possible to explain some mysterious facts of free-word-order phenomena in colloquial Russian. I consider: a) the agreement status of scrambled NPs; b) the role of referentiality in the movement properties of NP; c) weak crossover with scrambled NPs. On a more theory-internal plane, I also provide arguments in favor of the homogeneity of chains. One of the purposes of this paper is to offer empirical support for the claim that A'-chains cannot contain adjunction links. This leads to the natural concept of chain homogeneity: all the processes in a grammar create homogeneous chains, i.e., all the positions occupied by members of a chain are uniform with respect to some properties. Discussing the difference in movement properties between arguments and adjunct, Rizzi (1990) accounts for that difference as related to the property "referential/nonreferential", and proposes to restrict the use of referential indices to arguments (referential expressions). It is currently a widespread practice to use indices as a device to represent the relationship between elements that have undergone operations of some kind such as, movement and matching. That is to say, a referential index is licit on a given linguistic representation only if it is associated to a referential θ-role. It follows that no movement as such is linked to coindexation. But without coindexation, we need a definition of antecedent-government that does not make reference to coindexation, so that it could apply to indexed and nonindexed material alike. We can replace the coindexation requirement of the usual definition with a nondistinctness requirement. However, Russian data force me to the conclusion that the nondictinctness requirement holds of referentiality per se. but not of indices. Finally, I have shown that there are no inherent A/A' properties in X<SUP>max</SUP>-adjunction-chains. Everything depends on the moved XP. If the foot of an adjunction chain is in A-position, the head may be interpreted as an argument. If the foot is in A'-position, the head may not be interpreted as an argument. However, since any kind of XP may move via scrambling in Russian, it is best to state that a position created by adjunction is formally irrelevant to A/A' status-everything depends on what occupies the position, the lexical properties of governors, and specific conditions of an expression.