• Journal of Power System Engineering
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• v.21 no.6
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• pp.13-20
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• 2017

Ni-base superalloy Haynes 282 was developed as a gas turbine material for use in the ultra-super-critical stage (USC) of next-generation coal-fired power plants. Temperatures in the USC stage exceed $700^{\circ}C$ during operation. In spite of its important role Haynes 282 in increasing the performance of high-pressure turbines, as a result of its high-temperature capability, there is little information on the microstructure, deformation mechanism, or mechanical properties of the cast condition of this alloy. The aim of present study is to examine the creep properties of cast alloy and compare with wrought alloy. The ${\gamma}^{\prime}-precipitates$ were coarsen with the increase of aging time ranging from 8 to 48 hrs. A creep test performed at $750^{\circ}C$ showed faster minimum creep rate and shorter rupture lifetime with the aging time. A creep test performed showed only a slight difference in the rupture life between cast and wrought products. Based on the creep test results, the deformation mechanism is discussed using fractographs.

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.199-206
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• 2012

Unstiffened seated connections (USC) ensure easy installation and safety during erection, thereby making the process more economical. USCs consist of a seat angle for carrying the beam's reactions and a top angle to provide beam stability. These angles are bolted or welded to the beam and supporting member. This paper sought to propose a design table for the weld strength of such connections obtained from the elastic vector method (EVM) and the instantaneous center-of-rotation method (ICM) in terms of calculating the eccentricity. Also, the proposed design table is compared with both AISC and KBC specifications.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.324-326
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• 2004

l2wt%Cr Steel has been applied on turbine bucket and nozzle partition material of power plant. Turbine bucket and nozzle get damaged by solid particle within steam, therefore they are protected by surface treatments such as ion nitriding, boriding and chrome carbide HVOF spray coating. In this study, solid particle erosion(SPE) characteristics after these surface treatments are examined at operating temperature 540$^{\circ}C$ and 590$^{\circ}C$ of fossil power plant and the mechanism of damage was studied. Erosion of 12wt%Cr steel is originated by micro cutting and that of boriding and chrome carbide HVOF spray is originated by these mechanism - repeating collision, crack initiation and propagation. As the results of SPE test at 540$^{\circ}C$ and 30$^{\circ}$ impact angle that is the most commonly occurred in power plant, Boriding had the best SPE -resistance property, Cr$_2$C$_3$-25(Ni20Cr) HVOF spayed and ion nitrided samples were also better than bare metals(l2wt%Cr Steels). At 590$^{\circ}C$ and 30$^{\circ}$ impact angle, Boriding had also the most superior characteristic and HVOF spay sample was better than bare metal.

• Journal of the Korean Mathematical Society
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• v.33 no.3
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• pp.641-650
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• 1996

Let G denote an upper semicontinuous(usc) decomposition of an (n + k)-manifold M into closed, connected n-manifolds. What can be said about the decomposition space B = M/G\ulcorner What regularity properties are possessed by the decomposition map $p : M \to B \ulcorner$ Certain forms of these questions have been addressed by D. Coram and pp. Duvall [C-D].

• Review of KIISC
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• v.28 no.1
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• pp.29-35
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• 2018

Passphrases are considered to be more secure than passwords since they are longer than passwords. However, users choose predictable word patterns and common phrases to make passphrases memorable, which in turn significantly lowers security. While random passphrases appear to be stronger, surprisingly they are neither strong nor memorable. In this paper, we present the latest passphrase research, and introduce a new way to create a passphrase using mnemonics. Passphrase generation using mnemonics shows promising results in improving both strength and memorability.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.313-315
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• 2006

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2003.11a
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• pp.115-119
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• 2003

The green space become more important in the city. It is shown as the urban neighborhood park. But the current problem of urban neighborhood parks planning in Ulsan is uniform without reflecting area's characteristic. The Purpose of this study is to propose the planning methods of urban neighborhood parks by surveying characteristic of each urban neighborhood parks in Ulsan actual states and use behaviors.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.214-216
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• 2002

UDP를 이용하는 멀티캐스트에 있어서 에러 복구는 서비스의 신뢰성을 위해 반드시 필요한 알고리즘이다. 본 논문에서는 기존 라우터 기반의 에러 복구(Router-Assisted Schemes)알고리즘을 이용해서 라우터에 의한 에러 복구의 효율성이 증가하도록 하였다. 본 논문에서는 USC／ISI에서 개발한 네트워크 시뮬레이터인 NS-2를 이용하여 에러 복구 기능을 구현하였다. 또한 시뮬레이션을 통해 라우터에 멀티캐스트 에러 복구 방식이 적용되었을 경우, 기존의 에러 복구 방식의 효율성 향상이 가능함을 보이려 한다.

• Electronics and Telecommunications Trends
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• v.33 no.2
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• pp.56-63
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• 2018

A light field (LF) is a field for expressing the intensity and direction of light reflected from a subject in a 3D space. Dual LF cameras are equipped in smart phones in Korea, mainly those by Samsung and LG. Lytro, Apple, Nvidia, MIT Media Lab, Magic Lip, and NHK are also developing LF camera technologies. LF displays are being researched by ETRI, Samsung Electronics, KIST, KAIST, SNU, MIT Media Lab, USC, HP, Apple, Microsoft, SeeReal, Musion Eyeliner, Dimenco, and Holografika.

• 기계와재료
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• v.22 no.2
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• pp.20-30
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• 2010

석탄화력발전소의 효율향상은 스팀온도 및 압력의 증가를 통해 꾸준하게 이루어지고 있으며, 이러한 고효율의 화력발전은 사용 연료의 감소 뿐 아니라 $SO_x$, $NO_x$, $CO_2$ 등의 환경 가스배출을 감소시키는 효과도 있다. 이에 따라 운전조건을 고온, 고압화하려는 노력이 전 세계적으로 꾸준히 전개되고 있으며, 경제성 있고 높은 고온특성을 갖는 터빈 및 보일러 소재확보 여부가 발전소 건설 가능성을 결정하는 가장 주요한 요소 중 하나로 작용하고 있다. 본 고에서는 USC(Ultra Super Critical) 조건에 사용하기 위한 소재의 개발과정과 현대 사용되고 있는 다양한 발전용 고온소재의 특징에 대해 기술하고자 한다.