• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 2003년도 동계학술대회
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• pp.399-405
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• 2003

A new type of signature scheme, called NTRUSign, based on solving the approximately closest vector problem in an NTRU lattice was proposed in［7］,［8］. However no security proof against chosen messages attack has been made for this scheme. In this paper, we show that NTRUSign signature scheme contains the weakness of malleability. From this, one can derive new valid signatures from any previous message-signature pair which means that NTRUSign is not secure against strongly existential forgery.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2001년도 춘계정기학술대회
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• pp.305-314
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• 2001

본 논문해서는 m-커머스의 대표적인 성공 사례로 꼽히고 있는 NTT DoCOMo의 i-mode 서비스에 초점을 맞추어 성공요인과 그러한 성공을 이끌어 내는데 결정적인 역할을 담당한 웹 페이지 기술언어에 대해 살펴보았다. 분석 결과에 근거하면, i-mode 서비스의 대대적인 성공은 끊임없이 Positive Feedback의 계기를 만들어 냄으로써 가능하게 되었는데, 그것은 다름 아닌 C-HTML이라는 웹페이지 기술언어의 채용이 많은 역할을 하고 있다.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 봄 학술발표논문집 Vol.30 No.1 (C)
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• pp.460-462
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• 2003

본 논문은 현재 18M, 마이크로소프트, SAP등이 운용하고 있는 대표적인 공용 UBR(UDDI Business Registry) 노드들과 국내에서 개발된 K-UDDI, 일본의 NTT에서 운용하는 UBR노드에 대해 각각의 특징을 서로 비교해 본다. 또한 간단한 모니터링 프로그램을 구현하여, 각각의 UDDI 비즈니스 레지스트리에 등록되고 있는 전체 비즈니스 개체와 비즈니스 서비스 수의 증감 추이를 관찰하고, 등록된 비즈니스 개체별 링크된 WSDL파일의 유효함의 여부를 실행한 결과물을 통해 현재 운용중인 공용 UDDI 레지스트리의 활성화 정도를 분석해 본다.

• Journal of Computing Science and Engineering
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• 제7권2호
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• pp.99-111
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• 2013

Approximating a divergence between two probability distributions from their samples is a fundamental challenge in statistics, information theory, and machine learning. A divergence approximator can be used for various purposes, such as two-sample homogeneity testing, change-point detection, and class-balance estimation. Furthermore, an approximator of a divergence between the joint distribution and the product of marginals can be used for independence testing, which has a wide range of applications, including feature selection and extraction, clustering, object matching, independent component analysis, and causal direction estimation. In this paper, we review recent advances in divergence approximation. Our emphasis is that directly approximating the divergence without estimating probability distributions is more sensible than a naive two-step approach of first estimating probability distributions and then approximating the divergence. Furthermore, despite the overwhelming popularity of the Kullback-Leibler divergence as a divergence measure, we argue that alternatives such as the Pearson divergence, the relative Pearson divergence, and the $L^2$-distance are more useful in practice because of their computationally efficient approximability, high numerical stability, and superior robustness against outliers.

• 무역상무연구
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• 제34권
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• pp.157-185
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• 2007

The purpose of this thesis is to contribute to the activation of e-contract service for one stop e-trade by analyzing the problems and its solutions in e-contract service at home and abroad. In order to achieve the purpose of this thesis, case studies are done on e-contract service providers such as CECTRUST service of NTT DATA in Japan and HanCM.com of Haansoft in Korea and user companies such as Taisei Corporation using CECTRUST service and Hyundai Card using HanCM.com. The problems in the e-contract service are the lack of e-contract service providers, rare publicity of e-contract service, limited use of e-contract service at only home, higher pricing for e-contract service, short time management of e-contract documents by service providers, no application of newly developed security technology to e-contract service, unsatisfaction of requirements of e-contract service provider as trusted third party, absence of lower pricing e-contract service by service provider, authorizing key error in electronic signature under recognized authentication system in case of fail in renewal of digital certificate and reproduction of digital certificate. The solutions of these problems are the upbringing of e-contract service providers, broad publicity of e-contract service, development of e-contract service on a global basis, establishment of lower pricing for e-contract service, long time management of e-contract documents by service providers, application of newly developed security technology such as bio technology to e-contract service, satisfaction of requirements of e-contract service provider as trusted third party by designation of recognized e-document repository, development of lower e-contract service by way of application service provider(ASP), introduction of time stamping of e-contract document and signature key value. The limitation of this thesis is that the problems and its solutions could not meet with the broad recognition as they are conferred by intuition because of few e-contract service provider.

• 말소리와 음성과학
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• 제9권1호
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• pp.1-7
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• 2017

Previous studies have reported on the overlapping of $F_1$ and $F_2$ distribution for the vowels /o/ and /u/ produced by young Korean speakers of the Seoul dialect. It has been suggested that the overlapping of /o/ and /u/ occurs due to sound change. However, few studies have examined whether speech rate influences the overlapping of /o/ and /u/. On the other hand, previous studies have reported that the overlapping of /o/ and /u/ in syllable produced by male speakers is smaller than by female speakers. Few reports have investigated on the overlapping of the two vowels in read speech produced by male speakers. In the current study, we examined whether speech rates affect overlapping of /o/ and /u/ in read speech by male and female speakers. Read speech produced by twelve young adult native speakers of Seoul dialect were recorded in three speech rates. For female speakers, discriminant analysis showed that the discriminant rate became lower as the speech rate increases from slow to fast. Thus, this indicates that speech rate is one of the factors affecting the overlapping of /o/ and /u/. For male speakers, on the other hand, the discriminant rate was not correlated with speech rate, but the overlapping was larger than that of female speakers in read speech. Moreover, read speech by male speakers was less clear than by female speakers. This indicates that the overlapping may be related to unclear speech by sociolinguistic reasons for male speakers.

• 상하수도학회지
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• 제30권5호
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• pp.501-509
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• 2016

In this study, a flat-type photocatalytic reactor is applied under solar irradiation for simultaneous treatment of target pollutants: reduction of Cr(VI) to Cr(III) and oxidation of EDCs (BPA, EE2, E2). An immobilized type of photocatalyst was fabricated to have self-grown nanotubes on its surface in order to overcome limitations of powdery photocatalyst. Moreover, Ti mesh form was chosen as substrate and modified to have both larger surface area and photocatalyst content. Ti mesh was anodized at 50V and $25^{\circ}C$ for 30min in the mixed electrolytes ($NH_4F-H_2O-C_2H_6O_2$) and annealed at $450^{\circ}C$ for 2 hours in ambient oxygen to have anatase structure. Surface characterization was done with SEM and XRD methodologies. Fabricated NTT was applied to water treatment, and coexisting Cr(VI) and organics (EDCs) enhanced each other's reactions by scavenging holes and electrons and thus impeding recombination. Also, several experiments were conducted outdoor under direct sunlight and it was observed that both solar-tracking and applying modified photocatalyst were proven to enhance reaction efficiency.

• 정보보호학회논문지
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• 제14권1호
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• pp.3-13
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• 2004

전자상거래가 일상생활에서 급격히 확산되고 있다. 그 중 하나의 분야가 티켓, 쿠폰, 라이센스 등과 같은 권한(rights)을 발행 전달해주는 디지털 권한$.$전달 시스템이다. 현재까지 제안된 디지털 권한 전달 시스템은 크게 디지털 권한을 계좌의 형태로 관리하는 계좌 기반 방식(온라인 방식)과 디지털 권한을 스마트카드에 저장하여 전달하는 스마트카드 기반 방식(오프라인 방식)으로 분류할 수 있다. 최근 NTT는 스마트카드 기반 권한 전달 시스템에서 권한의 복사방지를 할 수 있는 기능을 제공하는 FlexToken 시스템을 제안하였다. 이들의 방식에서는 사용자들의 익명성을 보장하기 위해 Petersen과 Horster의 방식을 사용할 것을 제안하였다. 그러나, Petersen과 Horster의 방식은 사용자들이 불연계성(unlinkablity)을 만족하는 서명을 생성하기 위해 매번 다른(one-time) 공개키와 개인키 쌍(pseudonym public key/secret key)을 생성하여 등록해야 하는 문제점이 있다. 이러한 문제점을 해결하기 위해, 본 논문에서는 그룹서명을 사용하여 익명성이 보장되는 디지털 권한$.$전달 시스템을 제안하고자 한다. 이 논문은 디지털 권한$.$전달 시스템에 스마트카드기반 그룹서명을 처음 적용하였다는 점에서 의의가 있다.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 2002년도 종합학술발표회논문집
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• pp.495-498
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• 2002

The need for network protection, accounting and resource management in foreign administrative domain requires appropriate security services. In this paper, we propose an access control protocol to support the authentication between mobile node and visiting subnet. Our hybrid way of approach aims to reduce computational overhead and minimize the use of network bandwidth. We also propose non-certificate based public-key cryptography to provide non-repudiation, which does not require CRL retrieval and certificate validation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.60-63
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• 1996

This study deals with the nonlinear H$_{\infty}$ control problem of linear system using nonlinear weight. Generally the solvable condition of nonlinear H$_{\infty}$ control problem is given by the Hamilton Jacobi equality or inequality, but it is very difficult to solve. In this study, some constraints of nonlinear weight reduce the solvable condition to linear Riccati equation. Some examples of the control system design using nonlinear weight are shown.n.