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Material Removal of Glass by Magnetorheological Fluid Jet
김욱배,남은석,민병권,최두선,제태진,전은채 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.4
Magnetorheological (MR) fluid jet polishing is a material removal process for precision products such as optical elements. It ischaracterized by a jet flow that is stabilized by a magnetic field, and a highly predictable machining spot. The behavior of the particlesin an MR fluid slurry near a target wall surface is conceptually described. In experiments with a BK7 glass specimen, various removalspots are created by impingement of MR fluid jets at velocities of 10~30 m/s, using MR fluids of different compositions, and differentprocessing durations. The tangential MR fluid flow along the part surface is assumed to be responsible for material removal, andtheoretical models for the prediction of material removal are developed, using the conventional wear model and granular flow theory. The constitutive relation between the shear stress and the shear rate changes as the jet velocity increases, which has a critical effecton the behavior of material removal. CFD analysis is performed to calculate the wall shear rate. The proposed models agree withthe experimental results with respect to the distribution of the material removal rate. Additionally, the surface topographies of polishedparts are discussed, with regards to the particle behavior.
김욱배 한국금융법학회 2023 金融法硏究 Vol.20 No.2
금감원의 차질 없는 검사업무 수행은 우리나라 금융시스템의 건전성을 확보하는 핵심적인 요소이다. 그간 금감원은 금융회사 등의 검사방해행위를 방지하기 위해 엄정하게 대처하여 왔으나, 허위자료 제출, 자료 삭제·은폐 등 의도적이고 조직적인 검사방해는 지속적으로 발생하고 있다. 이는 공권력의 권위와 위상이 높지 않은 우리나라 사회의 특성이 반영된 측면도 있지만, 현행 법령상 검사방해에 대한 처벌 수준이 미약하여 위법행위에 대한 억지력이 크지 않고, 은밀한 검사방해는 금감원에서 적발할 수 없을 것이라는 그릇된 인식에서 기인하는 바가 크다. 게다가 과잉 검사 등 위법 논란 소지가 있는 검사권 행사는 자칫 금융회사 등의 검사방해행위를 유발하는 원인이 되기도 하고, 그간 금융회사 차원의 검사방해 방지 노력도 미흡한 실정이다. 금감원 검사방해에 대한 효과적인 대처를 위하여 우선, 고의적이고 위중한 검사방해에 대한 형사처벌과 엄정한 제재 조치를 통하여 검사방해를 통한 이익과 적발에 따른 불이익간 심각한 불균형을 해소해야 한다. 아울러 금융법별로 상이한 검사 방해규제를 체계적이고 통일적으로 규율함으로써 규제 공백을 제거하고, 제한적으로 강제 검사권을 도입하는 것도 도움이 될 것이다. 또한, 적법하고 공정한 검사업무를 지속 확립함으로써 금감원의 권위와 검사 신뢰도를 제고하고, 금융회사가 검사에 적극 협조하는 문화 정착을 유도하는 것도 고질적인 검사방해 방지에 효과적일 것이다. 이러한 개선방안이 충실히 시행된다면 금감원 검사의 실효성·신뢰성·수용성을 제고하는 효과를 거두어 금융회사의 건전한 경영 유지, 소비자보호 및 금융질서 확립 등에 크게 기여할 것이다. The integrity of the examination of the Financial Supervisory Service(FSS) is a crucial factor to ensure the safety and soundness of the financial system. While the FSS has tried its efforts to prevent intentional and organized obstructions of the FSS examination, the obstructive illegal behaviors have occurred continuously. In some aspects, a Korean society’s characteristic which disrespects a public authority may be a reason for obstructing examinations. However, a lower level of criminal penalty for the obstruction of examinations caused the failure to prevent illegal activity of the financial institutions. Also financial institutions mistakenly believed that obstruction of examination would not be detected forever by the FSS. In addition, a strong dissatisfaction of the officials or employees of financial institutions that the FSS excessively exercised its examination powers has led to the obstruction of examination in some cases. In addition, the efforts to prevent obstruction of examination by the financial institutions has been insufficient until now. In order to respond to the examination obstruction effectively, first of all, a significant obstruction of the examination must be subject to a strong criminal punishment, and regulators must strictly enforce the laws. Such actions may help to correct the imbalance between the benefits of obstructive behaviors and the demerits of the punishment of the examination obstructions. Also, systemizing and unifying various laws and regulations for obstructing examinations, and endowing the FSS a compulsive examination powers in a limited way will contribute to reducing the obstruction of examinations. Additionally, the FSS should ensure that its examiners provide a legitimate and fair examination services, which will increase reliability of the FSS. Finally, financial institutions should make their best efforts to prevent examination obstruction for themselves. The continuous implementation of suggestions mentioned above will strengthen the effectiveness and reliability of the FSS’ examination activities, and therefore, it definitely leads to the FSS’s goals to ensure the safety and soundness of the financial institutions, consumer protections and the establishment of financial stability in the Korean financial system.
Optical Design and Manufacturing Technology for High Resolution Laser Scanning Unit
김욱배,김형수,유재환,김형채,문수동 한국정밀공학회 2009 International Journal of Precision Engineering and Vol.10 No.5
This paper presents optics and fabrication process of key elements in a laser scanning unit for high quality laser beam printers or multi-function printers with over 600dpi optical resolution which today’s commercial system shows. Considering the light sources with different wavelength, optical characteristics in the laser scanning unit which includes a scanning lens and an athermalization element are explained. Also fabrication technologies to realize high resolution laser system such as mold design, core machining and injection molding processes are described. Finally, the hybrid lens as the athermalization element having refractive and diffractive surface is suggested to compensate thermal defocus. The hybrid lens is fabricated and their performance and effect on laser scanning unit are evaluated.