• Journal of the Korean Ceramic Society
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• v.30 no.6
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• pp.499-509
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• 1993

Structures of hematite(${\alpha}$-Fe2O3), Ba-ferrite(BaFe12O19) and Zn2Y(Ba2Zn2Fe12O22) were studied by powder X-ray diffraction(XRD) method. Powder XRD patterns of the ferrites were analyzed with the Rietveld method, and the final refined R-factors were RWP<0.01 and RI<0.03. The lattice parameters refined with hexagonal crystal system were a=5.0342${\AA}$, c=13.746${\AA}$ for hematite, a=5.8928${\AA}$, c=23.201${\AA}$ for Ba-ferrite, and a=5.8763${\AA}$, c=43.567${\AA}$ for Zn2Y. In the hematite, the oxygen parameter is 0.3072 and the Fe-O distances in FeO6octahedron are 1.941${\AA}$ and 2.118${\AA}$, close to the single crystal data of Blake et al.. In the Ba-ferrite, the Fe atom in oxygen trigonal bipyramid is displaced 0.155${\AA}$ away from the BaO3 mirror plane into 4e position. In the Zn2Y, 75% of Zn is located at the oxygen terahedral site in S-block.

• Polymer(Korea)
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• v.28 no.6
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• pp.509-518
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• 2004

Microdomain structures and crystallization behavior of the binary blends consisting of an asymmetric block copolymer and a homopolymer were investigated using small-angle X-ray scattering (SAXS), optical micro scope (OM) and differential scanning calorimetry (DSC). Poly(methyl methacrylate)-block-polystyrene block copolymer (PMMA-b-PS) (weight fraction of PMMA =0.53) was mixed with low molecular weight poly(vinylidene fluoride) (PVDF). As the PVDF concentration was increased, the morphological change from a lamellar to a cylindrical structure occurred. The crystallization of PVDF significantly disturbed the orientation of the pre-existing microdomain structure, resulting in a poorly ordered morphology. In the blends, PVDF exhibited unique crystallization behavior due to the PMMA block which is preferentially miscible to PVDF and the space constraint imposed by the microdomains.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.504-509
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• 2013

In this study, ZnSe-$TiO_2$ composites were synthesized by a facile hydrothermal-assisted sol-gel process and characterized by nitrogen adsorption isotherms (77 K), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectrophotometry. The photocatalytic activity was investigated by decoloration methylene blue (MB), methyl orange (MO), and rhodamine B (Rh.B) in an aqueous solution under visible light irradiation. The results revealed that the photocatalytic activity of the ZnSe-$TiO_2$ photocatalyst was much higher than that of pure$TiO_2$. The ZnSe nanoparticles, which act as a photosensitizer, not only extend the spectral response of $TiO_2$ to the visible region but also reduce charge recombinations.

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.505-509
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• 1988

Ethanol productivity of a xylose fermenting yeast (Candida sp. X-6-4l) isolated from soil was investigated in laboratory scale using Erlenmeyer flask and mini-jar tormentor. The optimal conditions of xylose fermentation in flask experiment were pH 4, asparagine as nitrogen source, xylose 20g/$\ell$, and in these condition, ethanol yield was about 80% to theoretical yield. Using mini-jar fermentor containing 5% total sugar with 2.5% xylose and 2.5% glucose, we obtained 2.3%(v/ v) ethanol and the corresponding efficiency was 72.3% of total sugar. In this case, the consumming speed of sugar under aerobic condition was faster than that of anaerobic condition, and glucose was used previously to xylose. The optimum concentration of xylose for ethanol fermentation in mini-jar fer-mentor scale was 5%, and the efficiency was 69% of total sugar(Alc.2.2% v/v).

• Journal of Digital Contents Society
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• v.10 no.4
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• pp.509-520
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• 2009

The advancement of network & application technology causes a major change for the use of IT(Information Technology) equipment, including computer and mobile system. In the process from beginning with main frame in the 1960s and 70's, through the server-client paradigm in the 1980s and toward the development of network computer since 90's, computer systems are now evolutioning from isolated physical system to complementary network based virtual system[1][2]. In network based computer system, application and data required for operation are stored at not client as local system, but at server[1]. User can use application & data on a server as if those are on a local client, and a client is now toward a developing thin and network friendly system. In this paper, we discuss possible ways for the efficient implementation of thin-client. For the use of remote application & data as if in local environment, we make use of X protocol. Unlike formal simple Client - Server paradigm, we design a Proxy for middle-tier server for the improvement of QoS and session persistence. X server, Xvfb(X virtual frame buffer) are implemented on thin client and Server, respectively and we applied XSMP(X Session Management Protocol) to our framework for session management. In the end, beyond simple transfer of server display, we suggest thin client framework for the transfter of remote server application over internet.

• Journal of Astronomy and Space Sciences
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• v.17 no.1
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• pp.19-32
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• 2000

A total of 1,018 observations (509 in B, 509 in V) of the eclipsing binary VW Cep was made during 7 nights from April through May in 1999 at Sobaeksan Optical Astronomy Observatory, using the CCD camera attached to the 61cm telescope. A time of minimum light of HJD2451327.2282 was determined from our data, and we constructed BV light curves with the data. Using, Wilson-Devinney’s binary model, we analized the light curves. The absolute dimension of $M_1=0.95M_\odot,M_2=0.33M_\odot,R_1=1.02R_\odot,R_2=0.66R_\odot$ of the VW Cep system were derived from our light curve solution and Kaszas et al. (1998) spectroscopic results.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.530-532
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• 1998

본 연구에서는 안전한 네이밍 서비스를 제공하는 기존 Secure DNS를 확장시켜 GUI방식의 관리자 인터페이스를 설계하였다. 따라서 시스템 설정에 대한 configuration과 보안관련 도구의 핵심이라 할 수 있는 로그의 관리가 용이해 졌다. 또한 관리자 인터페이스에 의해 각각의 자원 레코드에 대한 자동적인 삽입, 삭제가 가능하며, 암호화 알고리즘의 추가를 interactive하게 처리한다. 그밖에 기존 Secure DNS에서는 새로운 암호와 알고리즘을 추가할 때마다 재 컴파일 해야하는 단점이 있다. 이를 해결하기 위해 'Dynamic link interface'를 설계하였다. 이는 암호화 알고리즘의 입출력 표준을 정하고 이를 단일한 시스템 API로 구성하여 Secure DNS가 초기화 될 때 동적 라이브러리를 사용하여 각각의 암호화 알고리즘을 메모리에 적재하는 방식을 택한다. 그 밖에 Secure DNS를 이용하여 제공할 수 있는 응용방안으로 개인의 공개키 분배서비스와 X.509 체계를 이용한 인증서를 제공하는 서비스를 제안한다. 따라서 본 연구에서는 인터넷의 기본 인프라스트럭쳐인 DNS를 최대한 활용할 수 있는 여러 가지 방안과 그 해결책을 제시한다.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.519-523
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• 2004

In this paper we challenge the user Authentication using KerberosV5 authentication protocol in WPKI environment. This paper is the security structure that defined in a WAP forum and security and watches all kinds of password related technology related to the existing authentication system. It looks up weakness point on security with a problem on the design that uses wireless public key based structure and transmission hierarchical security back of a WAP forum, and a server client holds for user authentication of an application layer all and all, and it provides one counterproposal. Therefore, We offer authentication way solution that connected X.509 V3 with using WIM for complement an authentication protocol KerberosV5 and its disadvantages.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.979-982
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• 2006

암호 API 및 PKI 클래스를 토대로 하는 PKI 시스템의 개발은 암호 알고리즘을 활용한 보안 서비스의 중요한 위치를 차지하고 있으며, 현재 네트워크 기반의 각종 서비스에서 강력한 보안 기능을 제공하는 부분으로, 각종 보안 서비스의 제공을 위해서 가장 먼저 구축되어야 할 부분이다. 본 논문에서는 자바 암호 API 및 PKI 관련 클래스를 바탕으로 사용자 인증(User Authentication), 인가(Authorization), 부인-방지(Non-Requdation), 전자서명(Electronic Signature) 등의 보안 서비스를 제공할 수 있는 X.509 전자인증서를 발행하는 PKI 시스템을 연구하였으며, 향후 각종 보안 서비스의 제공에 있어서 중요한 위치를 차지할 수 있을 것이다. 또한, 자바 기반의 PKI 시스템은 이식성이 매우 높으며, 개별 서비스에 대한 모듈 형식으로 구성되어 있어, 그 활용의 범위가 고정되지 않고 다양한 시스템 및 서비스에 적용할 수 있는 장점을 가지고 있다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.159-162
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• 2009

Surface lighting using OLEDs for desk/task lighting has been analyzed its electrical and optical characteristic with a fluorescent lamp which has triple wavelength peak. We have confirmed the good possibility of OLEDs for desk/task lighting. Our engineering sample which has fabricated by co-worker has its characteristics which are luminous efficacy 11.781m/W at 509mW, CRI Index 75, CCT 4479K, CRI coordinate x=0.378, y=0.4547, respectively. Addinationly another OLEDs samples are used for compartive analysis in view of desk/task lighting.