• ETRI Journal
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• 제31권6호
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• pp.636-641
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• 2009

ZnO nanofibers were electro-spun from a solution containing poly 4-vinyl phenol and Zn acetate dihydrate. The calcination process of the ZnO/PVP composite nanofibers brought forth a random network of polycrystalline wurtzite ZnO nanofibers of 30 nm to 70 nm in diameter. The electrical properties of the ZnO nanofibers were governed by the grain boundaries. To investigate possible applications of the ZnO nanofibers, their CO and $NO_2$ gas sensing responses are demonstrated. In particular, the $SnO_2$-deposited ZnO nanofibers exhibit a remarkable gas sensing response to $NO_2$ gas as low as 400 ppb. Oxide nanofibers emerge as a new proposition for oxide-based gas sensors.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2005년도 하계학술대회
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• pp.217-221
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• 2005

도시의 기능이 날로 커져가고 땅속 지하매설물은 포화상태에 이르렀다. 또한 시민들의 의식 수준이 높아가면서 도시에서의 굴착시공은 민원유발과 교통소통장애 문제로 날로 어려워지고 있는 것이 현실이다. KT에서는 무인 및 유인 통신구를 건설할 수 있는 장비를 이미 개발한바 있으며, 본 연구를 통해 도심지에서 보다 효율적으로 통신관로 ${\Phi}50mm,\;{\Phi}150mm,\;{\Phi}300mm$를 시공할 수 있는 장비를 개발하게 되었다. 도시는 복잡하기 때문에 비개착 시공에 있어서 시공 점용면적이 상대적으로 많을 경우 어려움을 겪게된다. 소구경 비개착 장비인 XS-300은 길이 1.45m 폭 0.8m 높이 0.97m 이며 중량은 700kg인 소형장비인 것이 특징이다. XS-300은 도심지에서 통신맨홀 터파기 부분을 압입구로 활용할 수 있으며 경제적인 비용으로 개착식 시공이 불가한 구간에 대한 인입관로 구성과 지하장애물 하월시공, 도로횡단 시공 시에 적합한 장비이다. 특히 타 시설물을 관통한 불량통신시설과 재해에 취약한 통신시설에 대해 안전하고 경제적인 비용으로 이설시공을 할 수 있으며 통신인프라 기초시설 안정화 및 품질고도화에 기여할 수 있을 것이다.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 2003년도 동계학술대회
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• pp.625-633
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• 2003

무선랜은 현재 무선 네트워크에서 매우 중요한 역할을 차지하며, 앞으로의 차세대 무선 통합네트워크에서 또한 그 비중이 매우 높아 질 것이다 특히 핫스팟과 같은 공중망서비스의 확산으로 무선 인터넷 등의 차세대 정보 컨텐츠 산업의 중요한 매체로 부각되고 있다. 이에 부합하여 무선랜 서비스에 있어 사용자의 프라이버시(Privacy) 및 접근제어(Access Control), 인증(Authentication), 과금(Accounting), 빌링(Billing) 등의 다양한 보안 문제가 중요한 이슈로 대두되고 있다. 본 논문에는 공중 무선랜에서의 이동성이 고려된 인증 모델을 여러 국제 표준에 맞추어 제안하고, 그에 대한 검증 결과를 함께 제시한다. 제안된 모델은 상호 연동성 및 호환성을 보장하기 위해 Diameter를 기반 기술로 사용하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2001년도 춘계학술발표논문집 (상)
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• pp.263-266
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• 2001

상호 연결망에서 임의의 두 노드 사이에 존재하는 노드 중복 없는 경로들의 집합을 Container라고 하는데, 본 논문에서는 계층적 하이퍼큐브 연결망의 Container가 n+1임을 보이고, 그 결과를 통하여 계층적 하이퍼큐브 연결망의 고장지름이 dia(HCN(n,n))+4 이하임을 보인다. 이러한 Container는 노드간에 메시지를 전송하는 시간을 줄일 수 있으며, 연결망의 노드 몇 개가 고장이 발생해도 통신지연시간이 발생하지 않음을 의미한다.

• 한국멀티미디어학회논문지
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• 제22권9호
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• pp.992-999
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• 2019

In this paper, I lay the foundation for creating a multiscale atlas that characterizes cerebrovasculature structural changes across the entire brain of a mouse in the Knife-Edge Scanning Microscopy dataset. The geometric reconstruction of the vascular filaments embedded in the volume imaging dataset provides the ability to distinguish cerebral vessels by diameter and other morphological properties across the whole mouse brain. This paper presents a means for studying local variations in the small vascular morphology that have a significant impact on the peripheral nervous system in other cerebral areas, as well as the robust and vulnerable side of the cerebrovasculature system across the large blood vessels. I expect that this foundation will prove invaluable towards data-driven, quantitative investigations into the system-level architectural layout of the cerebrovasculature and surrounding cerebral microstructures.

• 대한청각학회지
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• 제23권4호
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• pp.210-213
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• 2019

The auricle is a three-dimensional cartilaginous frame covered with thin overlying skin. Due to its complex features, reconstructing helical rim defects after the excision of an auricular mass is challenging. Shortage of subcutaneous tissue and the presence of a tightly bound epithelium further hamper the primary closure of lateral (anterior) auricular skin defects. We present herein a case in which we used a helical rim advancement flap along with an additional postauricular skin flap. We achieved a satisfactory esthetic result with minimal loss of helical diameter and a low risk of flap necrosis by preserving the vascular network of the flap. This technique is less traumatic and will facilitate faster healing as well as improved patient recovery.

• Journal of Audiology & Otology
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• 제23권4호
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• pp.210-213
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• 2019

The auricle is a three-dimensional cartilaginous frame covered with thin overlying skin. Due to its complex features, reconstructing helical rim defects after the excision of an auricular mass is challenging. Shortage of subcutaneous tissue and the presence of a tightly bound epithelium further hamper the primary closure of lateral (anterior) auricular skin defects. We present herein a case in which we used a helical rim advancement flap along with an additional postauricular skin flap. We achieved a satisfactory esthetic result with minimal loss of helical diameter and a low risk of flap necrosis by preserving the vascular network of the flap. This technique is less traumatic and will facilitate faster healing as well as improved patient recovery.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.281-284
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• 2005

Kerberos is system that offer authorization in internet and authentication service. Can speak that put each server between client and user in distributed environment and is security system of symmetry height encryption base that offer authentication base mutually. Kerberos authentication is based entirely on the knowledge of passwords that are stored on the Kerberos Server. A user proves her identity to the Kerberos Server by demonstrating Knowledge of the key. The fact that the Kerberos Server has access to the user's decrypted password is a rwsult of the fact that Kerberos does not use public key cryptogrphy. It is a serious disadvantage of the Kerbercs System. The Server must be physically secure to prevent an attacker from stealing the Kerberos Server and learning all of the user passwords. Kerberos was designend so that the server can be stateless. The Kerberos Server simply answers requests from users and issues tickets. This study focused on designing a SIP procy for interworking with AAA server with respect to user authentication and Kerberos System. Kerberos is security system of encryption base that offer certification function mutually between client application element and server application element in distributed network environment. Kerberos provides service necessary to control whether is going to approve also so that certain client may access to certain server. This paper does Credit-Control Server's function in AAA system of Diameter base so that can include Accounting information that is connected to Rating inside certification information message in Rating process with Kerberos system.

• 마이크로전자및패키징학회지
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• 제20권4호
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• pp.47-52
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• 2013

Gold wire has long been used as a proven method of connecting a silicon die to a substrate in wide variety of package types, delivering high yield and productivity. However, with the high price of gold, the semiconductor packaging industry has been implementing an alternate wire material. These materials may include silver (Ag) or copper (Cu) alloys as an alternative to save material cost and maintain electrical performance. This paper will analyze and compare the electrical characteristics of several wire types. For the study, typical 0.6 mil, 0.8 mil and 1.0 mil diameter wires were selected from various alloy types (2N gold, Palladium (Pd) coated/doped copper, 88% and 96% silver) as well as respective pure metallic wires for comparison. Each wire model was validated by comparing it to electromagnetic simulation results and measurement data. Measurements from the implemented test boards were done using a vector network analyzer (VNA) and probe station setup. The test board layout consisted of three parts: 1. Analysis of the diameter, length and material characteristic of each wire; 2. Comparison between a microstrip line and the wire to microstrip line transition; and 3. Analysis of the wire's cross-talk. These areas will be discussed in detail along with all the extracted results from each type the wire.

• 한국유체기계학회 논문집
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• 제13권5호
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• pp.43-53
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• 2010

This study investigates a design optimization of a rotating two-pass rectangular cooling channel with staggered arrays of pin-fins. The radial basis neural network method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of fluid flow and heat transfer with shear stress transport turbulent model. The ratio of the diameter to height of the pin-fins and the ratio of the streamwise spacing between the pin-fins to height of the pin-fin are selected as design variables. The optimization problem has been defined as a minimization of the objective function, which is defined as a linear combination of heat transfer related term and friction loss related term with a weighting factor. Results are presented for streamlines, velocity vector fields, and contours of Nusselt numbers, friction coefficients, and turbulent kinetic energy. These results show how fluid flow in a two-pass square cooling channel evolves a converted secondary flows due to Coriolis force, staggered arrays of pin-fins, and a $180^{\circ}$ turn region. These results describe how the fluid flow affects surface heat transfer. The Coriolis force induces heat transfer discrepancy between leading and trailing surfaces, having higher Nusselt number on the leading surface in the second pass while having lower Nusselt number on the trailing surface. Dean vortices generated in $180^{\circ}$ turn region augment heat transfer in the turning region and in the upstream region of the second pass. As the result of optimization, in comparison with the reference geometry, thermal performance of the optimum geometry shows the improvement by 30.5%. Through the optimization, the diameter of pin-fin increased by 14.9% and the streamwise distance between pin-fins increased by 32.1%. And, the value of objective function decreased by 18.1%.