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강산성 용액의 pH를 측정할 수 있는 미셀기반의 형광센서 개발
이정무,이성호,Lee, Jeongmoo,Lee, Seoung Ho 한국환경과학회 2020 한국환경과학회지 Vol.29 No.8
In this study, an effective fluorescence pH sensor based on conjugated polyelectrolyte micelles (CPMs) was devised for detecting extremely acidic conditions. An amphiphilic coumarin derivative (CC12-N), a building block, was prepared, into which an ionizable amino group, aryl amine, was incorporated as a potential hydrophilic moiety. This monomer displays self-assembled micelle formation in extremely acidic pH ranges, giving a hydrophobic π-extended conjugated system at the inner part and hydrophilic functionality at the periphery, resulting in efficient fluorescence intensity enhancement. This new micelle-based fluorescence provides an efficient sensing platform for detecting very low pH values in the presence of competing substances.
모드조합으로 구성된 단일과대하중모델의 지연거동에 대한 평가
이정무(Jeongmoo Lee),서기정(Kijeong Seo) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this study the propagation behavior of fatigue crack was evaluated with mode combination and change under single overloading and constant-amplitude loading conditions. This experimental model is single overload model consisted of mode combination. Modified compact tension shear specimen and mode-adjustable loading device were used in order to mode combination and change. We investigated change of fatigue life and characteristics of crack propagation behavior due to mode combination. The retardation area induced by mode combination was estimated by introducing mixed-mode overload plastic zone. We simplified types of retardation curves and established the assessment method for various retardation behaviors with mode combination by introducing retardation coefficient.
혼합모드 단일과대하중에 의한 하중상호작용이 피로균열 전파거동에 미치는 영향
이정무(Jeongmoo Lee),송삼흥(Samhong Song) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this study, when variable-amplitude load with various applying mode acts on the pre-crack tip, we examined how fatigue cracks behave. Hence aspects of the deformation caused by changing the applying mode of single overload and propagation behavior of fatigue crack were experimentally examined: What kinds of the deformation would be formed at pre-plastic tone could be evaluated? As applying mode of single of ·overloading changes, the deformation caused by tensile and shear loading variously showed in each applying mode. The different aspects of deformation make influence on propagation behavior between aspects of cracks under constant-amplitude fatigue loading after overloading with various modes. We tried to examine the relationship between aspects of deformation and fatigue behavior by comparing tire observed deformation at crack and crack propagation behavior obtained from fatigue tests.
이정무(Jeongmoo Lee),송삼홍(Samhong Song),서기정(Kijeong Seo) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2
In this study to execute the fatigue tests under combination load of variable-amplitude and variable-mode, loading mode was changed in each stage of single overload model. The shape and size of residual plastic deformation field which was formed by mixed-mode overloading were measured by using the C-scan method in this test. As applying mode of single overloading changes, the deformation caused by tensile and shear loading variously showed in each applying mode. The different aspects of deformation make influence on propagation behavior of cracks under constant-amplitude fatigue loading after overloading with various modes. Hence the propagation behavior in variable-mode and variable-amplitude load model was examined by considering the effects of load interaction for propagation behavior of fatigue cracks.
모드 Ⅰ 및 혼합모드 Ⅰ/Ⅱ 의 파단면에 대한 프랙토그래피의 정량화
서기정(Kijeong Seo),이정무(Jeongmoo Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Fracture surface roughness and asperity in fatigue crack propagation vary with changes in various loading parameters. Especially loading modes in the parameters have influence on crack driving force. As we know, if under Mixed-mode Ⅰ/Ⅱ, the crack driving force become decreasing more than under Mode Ⅰ, resulting in fracture surface roughness are improved. The aspects of the fracture surface roughness and asperity result from loading modes have been mostly confirmed or defined by SEM farctography. In this study fracture surfaces under Mode Ⅰ and Mixed-mode Ⅰ/Ⅱ observed using the C-scan and calculated contour area roughness parameter. We know conveniently that the aspects of the fracture surface with loading modes as a result of this.
하중작용각도와 균열닫힘수준에 따른 피로균열성장 특성 변화
서기정(Kijeong Seo),송삼홍(Samhong Song),이정무(Jeongmoo Lee) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2
Crack tip displacement behavior depends on combined types of different two stress components under mixed-mode loading conditions (MMLC). Crack closure level(CCL) is estimated with crack tip displacement behavior. The crack closure level is calculated from the information of crack tip displacement under MMLC. This information has been obtained from the high resolution optical microscope in direct observations of crack displacement behavior at the crack tip. Observed crack tip displacement is analyzed by using CTD vector to determine crack opening load. The various effects of MMLC on the crack closure are explained using crack opening ratio with crack length and mode mixture. The effective stress intensity factor considering crack closure is also discussed.
피로파면의 기하학적 형상을 바탕으로 한 응력진폭 변화와 혼합모드 하중관계에 관한 연구
서기정(Kijeong Seo),송삼홍(Samhong Song),이정무(Jeongmoo Lee) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Most cracks in the structure occur under mixed mode loading and those fatigue crack propagation behavior depends on the stress ratio. Hence. it is necessary to study the fatigue behavior under mixed-mode loading as the stress ratio changes. In this paper, the fatigue crack behavior was respectively investigated at stress ratio 0.33, 0.50 and we changed the loading application angle into 0°, 30°, 45°, 60° to apply various loading mode. These experimental results were evaluated by the shape of fatigue fracture surface using 2D or 3D images obtained from the C-scan method. As stress ratio and mode mixity change, the change of effective stress intensity factor and crack closure have effect on the fatigue behavior of cracks. The variation of fatigue crack behavior caused by the change of stress ratio and loading application angle could be explained by using the shape of fatigue fracture surface.