The Pattern of virus mutation among the family members infected with hepatitis B virus

학위논문(박사)--서울대학교 대학원 :의학과 예방의학전공,1998.Docto

Interfacial Reaction Between Steel Sheets and Zn Coating Layer

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GB boundary energy, diffusivity and mobility in BCC Fe : A Molecular Dynamics Study

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Effect of grain boundary and V carbide interface character on hydrogen embrittlement of steels: An atomistic simulation

DoctorAbstract Demanding for the use of high strength steels has been increased in the structural materials industry. However, Hydrogen embrittlement has been a serious obstacle to the use of high strength steels in structural applications for many decades. In the present study, methods to improve the hydrogen embrittlement resistance of steels are investigated by using atomistic simulation based on (semi-) empirical interatomic potentials. Firstly, the influence of hydrogen on the crack propagation behavior on grain boundaries of bcc iron is investigated using atomistic simulations. We found that the hydrogen segregation tendency on grain boundaries was closely related to the grain boundary energy, and the influence of hydrogen on the grain boundary crack propagation was different according to the GB orientation. Various crack propagation behavior (intragnanular cleavage crack, intergranular crack along GB and plastic deformation) were observed with hydrogen segregation. An intergranular crack occurred in most GBs, while plastic deformation (dislocation emission and twinning) occurred in Σ3 coherent twin boundary (CTB). The Σ3 CTB showed retarded crack propagation due to the plastic deformation and is thought to be effective in improving the HE resistance. Secondly, influence of the Fe/VC interface coherency on the hydrogen trap behavior is investigated using an atomistic simulation. For this purpose, the hydrogen trap tendency for coherent, semi-coherent and incoherent interfaces is analyzed. It is found that the coherent and semi-coherent interfaces strongly trap the hydrogen, while the incoherent interface traps the hydrogen weakly. Based on the difference in hydrogen trap behavior of each interface, the coherent and semi-coherent interfaces is expected to be effective in improving the hydrogen embrittlement resistance of steels. These work provides a mechanistic framework for guiding the microstructure design of steels for improved resistance of hydrogen embrittlement

용융아연도금강판에서의 상평형 거동 해석

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High performance optical network system based on reflective semiconductor optical amplifier

반사형 반도체 광증폭기(Reflective Semiconductor Optical Amplifier; RSOA)를 각 가입자의 광원으로 이용하는 광가입자망에서 상향신호의 전송품질을 현저히 개선한 광 가입자망 시스템에 관해 개시한다. 본 발명의 가장 큰 특징은, RSOA를 각 가입자의 광원으로 사용하는 광 가입자망 시스템에서 하향신호의 변조방식으로 맨체스터 포맷(Manchester format)을 사용함으로써, 각 가입자의 광원으로 RSOA를 사용할 때 발생하는 재변조된 상향신호의 품질저하 문제를 해결하여 상향신호의 전송성능과 시스템의 파워 버짓(power budget)을 개선한다는 것이다. 본 발명에 따르면, 파워 버짓과 재변조된 상향신호의 전송성능이 개선된 RSOA 기반 파장분할다중방식 수동형 광가입자망(Wavelength Division Multiplexing Passive Optical Network; WDM PON) 시스템의 구현이 가능하다

Long-reach access network employing coherent receiver

학위논문(박사) - 한국과학기술원 : 전기 및 전자공학과, 2011.2, [ iv, 70 p. ]한국과학기술원 : 전기 및 전자공학과

온간압연에 의한 박판주조 MgAl 복합판재의 계면강도 향상

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