• Proceedings of the KSME Conference
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• 2004.11a
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• pp.85-89
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• 2004

The inner side between HP stationary blades in #1 turbine of Nuclear Power Plant A is damaged by the FAC(flow assisted corrosion) which is exposed to moisture. For many years the inner side is repaired by welding the damaged part, however, FAC continues to deteriorate the original material of the welded blade ring. In this study, we have two stages to verify the integrity of stationary blade ring in nuclear power plant A. In the stage I, replication of blade ring is performed to survey the microstructure of blade ring. In the stage II, the stress analysis of blade ring is performed to verify the structural safety of blade ring. Throughout the two stages analysis of blade ring, the stationary blade ring had remained undamaged.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1168-1170
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• 2005

Nanoimprint Lithography(NIL) has increasingly been recognized as a key manufacturing technology for nanosized feature. One of the most important task for nanoimprint lithography is to provide the imprinting stamp with low price. The Stamp fabricated with Si based material by e-beam lithography, RIE is extremely expensive and its throughput is very limited and PDMS replica is too soft to hold high imprinting pressure.(>5atm) In this study, we present the imprinting stamp which can be easily replicated from original mold and is based on PVC film. Replication of original Si mold to PVC film was done by Hot embossing technique, ($120^{\circ}C$ of Temperature, 20 atm applied) As small as 100nm patterns were successfully transferred into PVC film. The size of stamp was up to 100mm in diameter.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.19-25
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• 1999

The research has extracted two kinds of specimen, one is rolling direction material(R-material) and the other rectangular of rolling direction(V-material), from Al alloy 7075 rolled. We have come to a conclusion by measuring crack propagation behavior with movement type microscope and Replica. 1) R-material shows 130% higher, approx. 39.2MPa in fatigue strength than V-material, approx. 29.4MPa. 2) In crack proportion, contrary to V-material growing directly toward specimen axis, R-material grows neared to shear direction. 3) The life proves that R-material is approx. 122% higher than V-material at 43.1MPa and approx. 135% higher at 47MPa. 4) The correlation between fatigue crack length and fracture life ratio applied to 'log(2a)=A+B ($N/N_f$)'equation shows inappropriate, because property value of Al alloy is low and the difference of chemical composition is high comparing with steel material.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.97-99
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• 2004

ONS나 E-mail 혹은 Instant Messaging등 메시지 애플리케이션에서 서버-클라이언트 모델은 scalability에 의한 한계가 있다. 이러한 문제를 해결할 수 있는 대안은 Peer-to-Peer 기반 정근방식이다. 하지만 이러한 환경에서는 기존의 P2P 시스템에 높은 데이터의 지속성과 Bounded Look-up Latency를 효과적으로 지원하는 방안이 필수적이다. 본 논문에서는 Replication을 통하여 Look-up Latency를 줄이기 위한 하나의 방법으로 Distributed k-ary Replication(DkR)을 제안한다. DkR은 source node와 root node 사이에 multi-path를 유지하고 Look-up Locality 특성을 이용하여 Replica를 배치함으로써 효율적으로 Look-up latency를 줄이게 된다. 마지막으로 DkR의 Replication 효과를 시뮬레이션을 통해서 확인을 해 보았다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.391-393
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• 2004

인터넷상의 사용자와 대용량 콘텐츠의 급증에 따른 서비스 저하의 문제를 해결하기 위하여 웹 서버를 분산 설치하여 지역 서버로 하여금 클라이언트의 요청에 응답하도록 하는 콘텐츠 분산 네트워크(CDN)가 사용되고 있다. 그러나 원본 서버로부터 분산된 지역 서버에 콘텐츠를 복제하여 서비스하는 CDN 환경에서는 원본 서버와 복제 서버와의 콘텐츠 일관성을 유지하는 일이 중요한 문제이다. 그러므로 본 연구에서는 콘텐츠 특상에 따라 Adaptive TTL(Time to Live)을 적용하고 원본 서버와 복제 서버가 서로 협력하는 콘텐츠 동기화 알고리즘을 제안한다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.3
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• pp.38-46
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• 2005

The destructive method is reliable and widely used for the estimation of material degradation but it have time-consuming and a great difficulty in preparing specimens from in-service industrial facilities. Therefore, the estimation of degraded structural materials used at high temperature by nondestructive evaluation such as electric resistance method, replica method, Barkhausen noise method, electro-chemical method and ultrasonic method are strongly desired. In this study, various nondestructive evaluation(NDE) parameters of the Barkhausen noise method, such as MPA(Maximum Peak Amplitude), RMS, IABNS(Internal Area of Barkhausen Noise on Signal) and average amplitude of frequency spectrum are investigated and correlated with thermal damage level of 2.25cr-1.0Mo steel using wavelet analysis. Those parameters tend to increase while thermal degradation proceeds. It also turns out that the wavelet technique can help to reduce experimental false call in data analysis.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.393-396
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• 2002

The objectives of the paper are to develop the infra-technologies for reclaiming the effluents from wastewater treatment plants and reusing for agriculture water. The Suwon wastewater treatment plant has been selected for wastewater reuse tests and the water quality and treatment efficiencies are investigated. Three levels of wastewater treatments that are the effluent from the plant, sand filtering, and ultra-violet treatment are applied in the pilot system. The randomized block method was applied to wastewater application to paddy rice with five treatments, three blocks, and two replica. The control was the plots with groundwater irrigation, the other treatments are to use polluted stream flow by pumping, in addition to three wastewater treatments. The block test plots and field plots have been monitored for the water quality, soil pollution, and health hazards during the crop stages.

• Journal of Powder Materials
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• v.21 no.5
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• pp.389-398
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• 2014

Macroporous ceramics with tailored pore size and shape could be used for well-established and emerging applications, such as molten metal filtration, biomaterial, catalysis, thermal insulation, hot gas filtration and diesel particulate filters. In these applications, unique properties of porous materials were required which could be achieved through the incorporation of macro-pores into ceramics. In this article, we reviewed the main processing techniques which can be used for the fabrication of macroporous ceramics with tailored microstructure. Partial sintering, replica templates, sacrificial fugutives, and direct foaming techniques was described here and compared in terms of microstructures and mechanical properties that could be achieved. The main focus was given to the direct foaming technique which was simple and versatile approach that allowed the fabrication of macro-porous ceramics with tailored features and properties.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.190-192
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• 2006

The clinical characteristics of photodamaged skin, such as coarse and fine wrinkle are not accurately evaluable with previous methods. Public awareness for wrinkle treatment and prevention which rely on proper assessment and evaluation of the underlying skin changes has been increased as the population ages. In this paper, we suggest an in-vivo method and instrument that allow us to acquire a wrinkle-enhanced image to improve the accuracy of quantitative and qualitative analysis for skin wrinkle. The method used involved white LED illumination and photography through polarizing filters. Finally, the polarized light photography yields an accurate and evaluable parameter of photodamaged skin, especially fine and coarse wrinkle.

• 보존과학연구
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• s.29
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• pp.45-64
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• 2008

'No-An-Dang' in 'Un-Hyeun palace' was using as a guesthouse by 'dea-won-goon' built in 1864. 'No-An-Dang tablet' exhibited in 'No-An-Dang' seems to be made by using the letters which were written by 'Choo-sa Kim Jeong-Hee'. This tablet was manufactured by special processes; wood frame which was made of a Korean white pine was drawn patterns by variety pigment and latticed inside are joined with 3 of horizontal square wooden sticks and 7 of vertical square wooden sticks, then several sheets of the paper mulberry put on this frame and sheets cut along the edge of letter attached lastly. This structure of tablet could cause more conservation problems than only made in wooden structures. Therefore, replica was made and exhibited in bad condition and original one kept in museum storage for effective conservation of artefacts.