• Phonetics and Speech Sciences
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• v.9 no.1
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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.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.5
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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.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.1
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• pp.3-13
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• 2004

E-Commerce is suddenly spreading in a daily life. A rights trading system is a system that circulates digital-tickets such as plane tickets, software license, coupon. There are two main approaches so far account-based and smart-card based systems. The NTT Proposed FlexToken, a new smart card based copy prevention scheme for digital rights. They Proposed using pseudonymous self certified keys of Petersen and Horster in order to ensure anonymity of users. However. Petersen and Holster's scheme should register a pseudonymous key pair at TTP (One-time) every time so that users create the signature which is satisfied with unlinkability property In this paper, we propose a new anonymous rights trading system using group signature. This paper has a meaning having applied to digital rights trading system an efficient smart card based group signature.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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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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• 1996.10a
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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.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.2
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• pp.75-82
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• 2014

MANET has various types of attacks. In particular, routing attacks using characteristics of movement of nodes and wireless communication is the most threatening because all nodes which configure network perform a function of router which forwards packets. Therefore, mechanisms that detect routing attacks and defense must be applied. In this paper, we proposed hierarchical structure attack detection techniques in order to improve the detection ability against routing attacks. Black hole detection is performed using PIT for monitoring about control packets within cluster and packet information management on the cluster head. Flooding attack prevention is performed using cooperation-based distributed detection technique by member nodes. For this, member node uses NTT for information management of neighbor nodes and threshold whether attack or not receives from cluster head. The performance of attack detection could be further improved by calculating at regular intervals threshold considering the total traffic within cluster in the cluster head.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2005.09a
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• pp.15-20
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• 2005

We developed a database system to enable efficient and high-throughput transposon analyses in rice. We grow large-scale mutant series of rice by taking advantage of an active MITE transposon mPing, and apply the transposon display method to them to study correlation between genotypes and phenotypes. But the analytical phase, in which we find mutation spots from waveform data called fragment profiles, involves several problems from a viewpoint of labor amount, data management, and reliability of the result. As a solution, our database system manages all the analytical data throughout the experiments, and provides several functions and well designed web interfaces to perform overall analyses reliably and efficiently.

• Information and Communications Magazine
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• v.25 no.9
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• pp.3-8
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• 2008

본고에서는 1998년 말부터 시작된 3GPP의 표준인 WCDMA, HSPA 및 LTE로의 진화 로드맵을 알아보고, 특히 최근의 중점 이슈인 LTE에 대한 추진 배경, 일반적 요구사항 및 기술적 요구사항의 개요에 대해 알아본다. LTE는 2004년 말에 필요성이 제기되어 2005년부터 본격 추진되었고 2008년 말이면 무선접속 분야는 표준이 거의 완료될 전망이다. 과거 WCDMA 에서 HSPA로 진화 시 호환성을 고려해서 조심스럽게 접근했던 것과는 달리 LTE에서는 호환성의 제약을 받지 않는 완전히 새로운 표준을 지향하여, 단순하면서도 효율적이고 유연한 기술표준을 목표로 작업이 수행되어 왔다. 무선통신 분야의 주류 기술이 되고 있는 OFDM, MIMO기술을 바탕으로 LTE기술은 Vodafone, Verizon, NTT DoCoMo등 많은 대형사업자로부터 차세대 기술로 선택되고 있으며 2010년경부터 상용화가 예상되고 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.661-664
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• 2007

일본의 상호접속은 전기통신사업법에 법적인 근거를 두고 설비를 보유한 특정 전기통신사업자가 설비를 보유한 다른 전기통신사업자로부터 상호접속의 요청이 있는 경우 다음의 특별한 사유를 제외하고는 상호접속을 이행토록 강제하고 있다. 특히, 1종 지정전기통신설비를 보유한 사업자(현재 NTT 동일본, NTT서일본이 각각 지정)는 고정계의 필수설비를 보유한 시장지배적사업자로, 필수설비 접근의 제한 및 지배력남용을 방지하기 위하여 강한 규제를 받고 있다. 특히, 상호접속부문에서는 LRIC에 의한 접속료 규제를 받는 유일한 사업자로 NIT가 지정되어 있는 상황이다. 반면, 2종 지정전기통신사업자(이동계 지배적사업자)와 기타의 전기통신사업자는 이러한 접속료 규제를 받기는 하지만 1종지정전기통신사업장와 같은 접속약관인가가 아닌 신고제를 적용받고 있다. 다만, 이용자들의 end-to-end 서비스의 보장을 위해 상호접속을 실시도록 하고 있다. 이에 본고는 현행 일본의 상호접속관련 규정 및 접속료 산정 guideline인 접속료 규칙을 살펴보고자 한다.

• Progress in Superconductivity
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• v.4 no.1
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• pp.32-36
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• 2002

We have measured the Hall effect in infinite-layer Sr／sub 0.9／La／sub 0.1／$CuO_2$ thin films grown by molecular beam epitaxy. We do not observe $T^{2}$ dependence of the cotangent of Hall angle, which is commonly observed in other cuprate High-Tc superconductors. Therefore, this result cannot be interpreted within two different scattering mechanism based on charge-spin separation theory. The mixed-state Hall effect shows no sign anomaly, implying that tile hydrodynamic contribution of vortex core is negligibly small.