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급냉응고/분말야금법으로 제조된 Al-Fe-V-Si 합금의 기계적 성질 (2) : 파괴기구에 관한 연구 Micromechanism of Fracture
이종철,이두영,이성학,김낙준 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.4
This study is concerned with a correlation between the microstructure and the micromechanism of fracture processes in an RSP/PM Al-8.5Fe-1.3V-1.7Si alloy. The specimens were exposed to the temperatures ranging from 150℃ to 480℃ for 100 hours, followed by room temperature tensile tests, fracture toughness tests and void initiation tests. This RSP/PM Al alloy did not show any significant change in room temperature tensile strength, tensile elongation and fracture toughness even after exposure up to 425℃ for 100 hours. However, tensile elongation and fracture toughness decreased significantly after exposed to 480℃ for 100 hours. Detailed microstructructural analyses showed that the alloy ahs a band structure due to non-uniform distribution of the silicide dispersoids. After exposure to 480℃, the formation of θ-Al₃Fe phases occurs at band structure boundaries by the dissolution of coarse silicide dispersoids, resulting in a loss of ductility and fracture toughness. The micromechanical processes involved in void and microcrack formation were identified and quantified. The results are interpreted using a simplified ductile fracture initiation model based on the basic assumption that crack extention starts to occur at a certain critical strain over a microsturcturally significant critical distance. This model enables us to correlate fracture toughness and microstructure, confirming that the formation of θ-Al₃Fe phases is the main metallurgical factor which contributes to the embrittlement phenomenon after exposure to 480℃ for 100 hours.
저탄소 마르텐사이트 강의 냉간압연과 온간압연을 통한 미세조직 개질
이종철,강의구,이중원,오창석,김성준,남원종 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
There have been a number of works on manufacturing ultrafine grained steels with average ferrite grain sizes of smaller than a few micrometers to develop beneficial high strength steels. Among microstructures in low carbon steels, lath martensite is known to be useful to produce an ultrafine grained ferrite matrix and finely globular cementite particle. Thus, severe plastic deformation and subsequent annealing at lower temperature of lath martensite would become an effective way to produce ultrafine grained steels. However, most ultrafine grained steels exhibited a total elongation of a few per cent in tensile tests. Such a defect is one of the primary factors restricting the potential applications of ultrafine grained steels. Therefore, the improvement of the strength-elongation balance is required for the application of ultrafine grained structural steels. In this study, the effect of deformation temperatures on microstructure, such as ferrite grain size and the distribution of cementite particles, and mechanical property of lath martensite steels, was investigated. Specimens were fabricated through cold rolling or warm rolling and subsequent annealing.
<전기설비 기술기준 세미나 발표자료> IEC 60364 규격의 최근 개정현황
이종철,Lee, Jong-Cheol 대한전기협회 2009 전기저널 Vol.- No.385
대한전기협회는 2008년 11월 25일 한전 서울사업본부 대강당에서 '전기설비 기술기준 세미나'를 개최했다. 이와 관련, 주요 발표내용을 시리즈로 소개할 계획이다.
이종철,김윤제,부진효 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.3
Electrode erosion is indispensable for atmospheric plasma systems, as well as for switching devices, due to the high heat flux transferred from arc plasmas to contacts, but experimental and theoretical works have not identified the characteristic phenomena because of the complex physical processes. In this study, we analyzed the electrical conductivity and the temperature of arc plasmas using the field-coupled computational techniques to consider the electrode erosion in a thermal puffer plasma chamber. Based on the results from the arcing history with metallic vapors, the thermal and electromagnetic characteristics near current zero were investigated using the electrical conductivity and the temperature of the arcing zone. Numerical results showed that the existence of electrode vapors made the arc temperature down during the high-current period and a negative effect with high electrical conductivity on the current interruption.
이종철,유시욱,김건희,이윤정 한국유전학회 2014 Genes & Genomics Vol.36 No.1
Drosophila ventral nervous system defective(VND) is a transcription factor containing tinman domain,homeodomain, and NK2-specific domain. The VND playsan essential role during the development of embryonicnervous system, however, little is known about its rolesbeyond embryonic stage. In this study, the expressionpatterns and levels of the VND during larval and adultstages were examined by using GAL4/UAS binaryexpression system and real-time PCR. The VND proteinwas expressed in larval brain, eye, and wing imaginal discs,implying possible roles of this protein in the larval tissuesother than embryonic nervous system. Gain-of-functionphenotypes of vnd were analyzed by crossing variousGAL4 drivers with UAS-vnd transgenic line. Interestingly,we observed the massive cell death in the tissues includingeye and wing discs where GAL4 is expressed. To downregulateendogenous vnd transcripts in the eye disc, UASvnd-IR (inverted repeat) was crossed with ey3.5-GAL4 line. Loss-of-function phenotypes of vnd also revealed the blackommatidial spots indicating apoptotic cell death in thetransgenic eye tissues. To identify a domain within theVND involved in apoptosis, VND mutant proteins wereectopically expressed in the eye disc. In contrast to VNDDtinmanand VND-Y54M mutant proteins, overexpressionof VND-DNK2 did not lead to cell death, indicating thatNK2-specific domain is responsible for apoptosis. Takentogether, our results suggest that VND might be involved inthe development of the various tissues after embryonicstages and in apoptosis via NK2-specific domain.
헬싱키 프로세스의 북한 인권 적용 가능성과 함의 -소련 및 동구 변화의 동학으로부터-
이종철 대한정치학회 2010 大韓政治學會報 Vol.17 No.3
심각한 북한의 인권 상황에 접하여 “헬싱키 프로세스”를 북한 인권에 적용하고자 하는 관심이 높다. 헬싱키 프로세스는 소련 및 동구의 인권 운동에 주요한 영향을 미쳤으며 궁극적으로 소련 및 동구의 체제 변화를 유인하는 외부 압력 기제로 작동하였다. 헬싱키 프로세스가 북한 인권에 주는 함의는 북한 인권 개선을 위한 꾸준한 문제제기와 국제적 공동노력의 강화 필요성이다. 구체적으로 헬싱키 체제의 북한 인권에의 적용 가능성과 효과적 방도는 다각도로 검토될 수 있다. “나선형 5단계론”에서 보듯이 북한 인권을 위한 외부의 노력은 장기적으로 북한 내 인권 운동을 촉발시키고 북한을 변화로 이끄는 데 중대한 기여를 할 것이다.