STS 304 강의 크리프 및 고온 저사이클피로균열전파 거동에 미치는 응력크기 및 응력파형의 영향

이치우,허정원,김광영,조용배 경남대학교 신소재연구소 1994 論文集 Vol.4 No.-

본 연구는 고온용 구조물 재료로 널리 사용되고 있는 STS304강을 650℃ 고온에서 공칭응력 σ_(n)=130 MPa와 σ_(n)=150MPa으로 실험하여 균열 전파거동에 미치는 응력 크기의 영향과 고온 저사이클 균열 전파 실험은 하중제어 하에서 대칭 삼각파형 fast-fast, 비대칭 삼각파형 fast-slow와 slow-fast 등으로 실험을 실시하여, 파형효과 중 반복속도 및 속도 비대칭 거동에 미치는 효과를 조사하였고, 모든 시험편에서 파단면의 형상을 조사하여 변형률 파형효과 및 응력파형효과에 따른 손상기구를 해석하고, 피로수명과 균열 전파속도의 결과를 비교 및 고찰하였다. 크리이프 균열전파 실험에서, 최대 응력강도 계수 K_(max)는 응력 크기 (σ_(n)=130MPa, σ_(n)=150MPa)에 관계없이 균열전파속도를 평가할 수 잇는 파라미터임을 보였다. 저사이클 고온피로 균열전파 실험에서, 반복속도가 빠른 fast-fast 파형에 비하여 반복속도가 느린 fast-slow와 slow-fast 파형의 경우에 균열전파속도는 현저하게 가속되며 또한, fast-slow 및 slow-fast 파형에서, 균열전파속도는 slow-fast 파형 경우가 fast-slow 파형보다 훨씬 빠르게 나타났으며, 이는 제하(negative loading)쪽보다 부하쪽(positive loading)의 하중속도가 느린 파형이 크리프 영향을 더 크게 받음을 의미한다. 그리고 파단면의 형상은 fast-fast 파형의 경우는 입내파괴를 보이고 fast-slow 파형의 경우는 입내파괴와 입계파괴가 혼재하며, slow-fast 파형의 경우는 입계파괴를 보였다. 입계파괴의 형상은 fast-slow 파형의 경우는 r형이며, slow-fast 파형의 경우는 w형이었다. The effects of stress amplitudes in creep and wave shape in fatigue on crack growth behavior of STS304 stainless steel have been investigated. Two kinds of stress amplitudes were considered in creep crack growth test : they were nominal stresses of σ_{n}=130MPa and an=150MPa Three types of wave shapes were considered in fatigue crack growth test : they were fast-fast, fast-slow and slow-fast(fast : 0.5sec, slow 500sec). The maximum stress intensity factor K_{max}, was a parameter able to evaluate crack growth behavior regardless of stress amplitude in creep crack growth test. The crack growth rates of wave shapes having long loading time were accelerated better than that of wave shape having short loading time, that is, the case of fast-slow and slow-fast were faster than that of fast-fast. The acceleration of the crack growth rate was affected much better by positive loading than negative loading, that is, the case of slow-fast was faster than that of fast-slow. Fractography of fractured surfaces correlated with the result of the crack growth behavior test.

연소진동의 발생과 그 진단 기술에 관한 연구

양영준,이치우 진주산업대학교 산업과학기술연구소 2007 산업과학기술연구소보 Vol.- No.14

Self-excited combustion oscillation has been occurred many industrial facilities, for example, such as boilers, gas turbines and various engines. The generation of self-excited combustion oscillation often leads to system destruction as well as environmental problem like noise. In order to predict the onset of self-excited combustion oscillation, detecting method of self-excited combustion oscillation was experimentally examined. For this purpose, the unique measures, which were based on the careful statistics of fluctuating properties in flames, were performed using pressure transducer and CCD camera.

고주파 표면경화강의 회전굽힘피로강도에 미치는 영향에 관한 연구

이치우,정상영 경남대학교 신소재연구소 1994 論文集 Vol.4 No.-

기계 구조용강 SM 45C을 고주파 표면 경화처리를 하여 회전 굽힘 피로시험하여 경도 분포, 조직, 피로강도 곡선 및 파괴 관찰을 하여 피로 파단점 N₁=10⁴사이클에서 표면기점파괴와 내부기점파괴가 나타나며 이는 피로 파괴가 시작되는 경계층 경계부에서는 마르텐사이트에 비해 상대적으로 연질 페라이트가 나타나고 이것이 파괴의 기점이 되며 모재의 열처리 영향에 EK라 경화층에서는 입계 파괴에서 연성파괴로 비경화층에서는 벽개 파괴로 파면 형태가 달라짐을 알 수가 있었다. Hardness, microstructure, fatigue strength curve and fracture types are observed by using the rotating-bending fatigue testing with the high frequeney surface hardening treated of structural steel SM 45C, and the results are appeared to the surface and internal fracture origin types at the fatigue life N,=l0⁴cycle. On the separatim parts of boundary layer occurring the fatigue fracture. It is given the soft-ferrite compare to the martensite, and fathermore could be predicted the different fracture types from the grain boundary fracture to ductile fracture on the hardened layer and to cleavage fracture on the non- hardened layer, by affecting the heat treatment of matrix.

양극성 장애와 Monocyte Chemoattractant Protein-1 유전자 다형성

배치운,김태석,장우영,김정진,이창욱,이수정,전태연,이철,백인호 大韓神經精神醫學會 2004 신경정신의학 Vol.43 No.5

Objectives : Several studies suggested that cytokines could be involved in the pathogenesis of mood disorders, while data for bipolar disorder is relatively deficient (BD). BD, Knowned to have a inherited tendency, has been considered to be related with T-helper cell system. This study was designed to investigate the association between polymorphism of monocyte chemoattractant protein-1 (MCP1) gene at promoter-2518 and BD. Methods : Patients with BD (n=92) in accordance with DSM-FV criteria and control subjects (n=114) participated in this study. DNA was extracted from whole blood and the MCP-1 gene promoter region was amplified by polymerase chain reaction-based method. Results : Genotype and allele distributions in patients with BD were not different from those of control subjects (p=0.587 ; p=0.384). Genotype and allele distributions in accordance to presence or absence of suicide attempt (p=0.423), family history (p=0.733) and psychotic feature (p=0.436) were not different between the two groups. Conclusion : Present study suggests that the MCP1 promoter -2518 polymorphism may not affect the susceptibility and clinical diversity of the development of BD.

Aromatic hydrocabon 분해세균의 검출과 그 plasmid 유전자의 특성

김치경, 김종우, 김영창, 민태익 忠北大學校 遺傳工學硏究所 1987 遺傳工學硏究 Vol.1 No.1

본문참고

급성 신우신염이 선행된 Escherichia coli 농흉 1예

차치운,조준형,김미진,오윤정,연재우,이성규,오미정,채지영,김수연 대한감염학회 2009 감염과 화학요법 Vol.41 No.5

We experienced a case of acute pyelonephritis which progressed to Escherichia coli bacteremia and later complicated by empyema in a 65-year-old female. She was successfully treated with intravenous antibiotic therapy and percutaneous drainage of empyema.

피틴산(Phytic acid)이 비브리오(Vibrio vulnificus) 패혈증에 미치는 영향

정영호,조천휘,이선우,임치환 충남대학교 농업과학연구소 2005 농업과학연구 Vol.32 No.1

Phytic acid chelates excellently the metallic ions and the positive ions, especially has high affinity with Fe^(2+) and Ca^(2+). Merits of phytic acid can be taked in easily, edibile and harmless to body, so it was investigated that phytic acid can be substituted for EDTA in this study. 1. The Intensificative effect of chelating agent and disinfective osmotic shock of Vibrio vulnificus The number of initial existent fungi measured 1.7x10^(6). The percentages of the survival fungi against the osmotic shock by distillated water were calculated at 1 minute, 3 minute and 5 minute after inoculation. The percentages of the survival fungi in Mg^(2+) were 92.5%, 91.8% and 79.8% at each time, the average percentage was 88%. Also the sudden extinction was observed around 1 minute after inoculation and the survival fungi were not observed from 3 through 5 minute in spite of repeated experimentation. 2. Influence of Vibrio vulnificus on the survival of the mice. The first mouse started to die in 180 minute after inoculation in case that the inoculating number was 2.3x10^(7) cfu/ml. All died within 4.5 hour. The average of survival time was 226 minute. The first mouse started to die in 228 minute after inoculation in case that the inoculating number was 0.8x10^(6) cfu/ml. All died within 5 hour. The average of survival time was 300 minute and the survival time was 1.3 times high. The tendencies of death in two cases were similar, but the fatal rate were largely dependent on inoculating number.

Lidocaine, Thrombin, Epinephrine 의 항균효과

김진우,이동건,전혜선,김승준,김석찬,안중현,김치홍,권순석,김영균,김관형,문화식,신완식,송정섭,박성학 대한감염학회 2005 감염과 화학요법 Vol.37 No.6

목적 : 기관지내시경 검사에서 흔히 사용되는 국소마취제인 lidocaine과 내시경시 지혈목적으로 사용되는 thrombin과 epinephrine이 각종 균주에 미치는 항균효과에 대해 알아보고자 하였다. 재료 및 방법 : 균주는 가톨릭대학교 성모병원에서 2004년 3월부터 2004년 9월까지 임상검체 에서 동정된 S. aureus, S. pneumoniae, K. pneumoniae, P. aeruginosa 각각 42, 42, 42, 43주를 대상으로 하였다. Lidocaine, thrombin, epinephrine 감수성 검사는 National Committee for Clinical Laboratory Standards (NCCLS, 2002)의 기준에 따랐다. 결과 : Lidocaine은 S. aureus, S. pneumoniae, P. aeruginosa에서 MIC_(50), MIC_(90) 모두 20,000 ㎍/mL 이었다. K. pneumoniae는 각각 10,000 ㎍/mL이었다. Thrombin은 S. aureus와 P. aeruginosa에서 MIC50 500 lU/mL 과 MIC_(90) 500 IU/mL 이상이었고, K. pneumoniae에서는 MIC_(50)과 MIC_(90)이 모두 500 lU/mL이상이었으나 S. pneumoniae에서는 MIC_(50)과 MIC_(90)은 125 IU/mL이었다. Epinephrine은 K. pneumoniae, S. pneumoniae에 대한 MIC_(50), MIC_(90)가 모두 >500 ㎍/mL이었고, S. aureus와 P. aeruginosa에 대한 MIC_(50), MIC_(90)가 모두 500 ㎍/mL이었다. 결론 : 기관지 내시경 검사에서 흔히 쓰이는 lidocaine, thrombin, epinephrine 등의 약제들이 호흡기 질환의 흔한 병원균인 S. aureus, S. pneumoniae, K. pneumoniae, P. aeruginosa 균주들에 대해 항균 효과가 있을 수 있어 세균배양검사에 영향을 미칠 수 있겠다. Background : We performed this stody to find out about antimicrobial effect of lidocaine which is commonly used local anesthetic, and thrombin and epinephrine used for hemostasis during bronchoscopic procedures. Materials and Methods : The microorganisms that were cultured from specimens obtained during bronchoscopy were Staphylococcus aureus (n=42), Streptococcus pneumoniae (n=42), Klebsiella pneumoniae (n=42), and Pseudomonas aeruginosa (n=43) collected from St. Mary's Hospital, from March to Sep 2004 were used for susceptibity testing. Susceptibility to lidocaine, thrombin, and epinephrine were tested according to the National Committee for Clinical Laboratory Standards. Result : MIC_(50) and MIC_(90) of lidocaine for S. aureus, S. pneumoniae, P. aeruginosa were all 20,000 ㎍/mL and that for K. pneumoniae were 10,000 ㎍/mL. MIC_(50) and MIC_(90) of thrombin for both S. aureus and P. aeruginosa was 500 IU/mL and above 500 IU/mL, respectively; that for K. pneumoniae were all above 500 IU/mL and for S. pneumoniae they were 125 IU/mL, MIC_(50) and MIC_(90) of epinephrine for K. pneumoniae and S. pneumoniae were above 500 ㎍/mL; that for S. aureus and P. aeruginosa were 500 ㎍/mL. Conclusion : We observed possible antimicrobial effect of lidocaine, thrombin, and epinephrine in vitro against pathogens such as S. aureus, S. pneumoniae, K. pneumoniae, P. aeruginosa, which are common respiratory microorganisms. The use of these agants could affect the result of bacterial culture.

연속주조내 용융금속 유동장의 수학적 모델링(Ⅰ)

이치우,이성우,정상영 경남대학교 신소재연구소 1992 論文集 Vol.2 No.-

연속주조 턴디쉬 및 신주조기술인 쌍롤박판 주조기내의 응용금속장을 예측하는 수학적 모델링을 개발하였다. 그 응용금속유동장을 위한 수학적 구성식은 난류성분을 표현하는 난류 Navier-Stock식을 근거하고 K-ε난류방정식과 함께 유동장예측 및 난류성분의 결과를 제시하였다. A mathematical modelling has been developed for describing the flowfilds of molten metal in the tundish and the twin-roller procss of continuous casting. The formulation of the tundish and the twin-roll process were dased on the turbulent Navies-Stokes equation in which allowance was made for the spatially distributed turbulent velocity field of molten metal. The calculation of turbulent properites using the two equation K-E turbulence model have been applied, and predicted results are presented.

Newton-Raphson Method와 Matrix를 이용한 고차방정식의 인수분해 기법

장영우,황치정 충남대학교 기초과학연구소 1995 忠南科學硏究誌 Vol.22 No.1

Application of Newton-Raphson iteration, partial differentiation and linear algebra in factoring both real and complex coefficient polynomials is presented. When factorizating complex polynomials, it is shown that calculations can be performed in real arithmetic only. Complex cases expand the matrix size by a factor of two due to the real-numbers-only computation. For complex cases with large matrices, the method to calculate inverse matrix and factor polynomials using quarter matrices is suggested.