• Journal for History of Mathematics
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• v.33 no.1
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• pp.21-32
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• 2020

Daniel Coit Gilman, the first president of Johns Hopkins University, aspired to build an ideal university focused on the competent faculty and their research. His plan was carried out through opening the first American graduate program, hiring professors with the highest-level research performances, assigning them less teaching burdens, and encouraging them to actively publish professional journals. He introduced Department of Mathematics as an initial model to put his plan into practice, and James Joseph Sylvester, a British mathematician invited as the first mathematics professor to Johns Hopkins University, made it possible in a short time. Their concerted efforts led to building the Department of Mathematics as a professional research institute for research, higher education, and expert training as well as to publishing American Journal of Mathematics.

• The Optical Journal
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• s.105
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• pp.49-56
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• 2006

한국광학기기협회에서는‘한·일 광산업 기술협력’을 보다 효율적으로 추진하기 위하여 해마다 일본 연수기관 및 기업에 대한 현장연수를 실시하고 있는 가운데, 올해는 처음으로 지난 8월에 일본정밀공학회(JSPE)에서 주최하는‘차세대 초정밀광학부품 나노가공기술연수’를 실시했다. 연수기관은 일본 센다이 소재의 동북대학(Tohoku University)으로 구리야가와 츠네모토 교수가 교육을 담당했다. 주요 연수 내용으로는 마이크로 광학부품가공/초정밀 비구면 렌즈 가공/전기점성유체를 이용한 비구면 렌즈 코아 연마/특수광학렌즈 SPDT 가공/초고속 가공/마이크로 AJM 가공/마이크로 초음파가공이며 본 고에서는 직접 연수에 참가 못한 독자들을 위해 연수내용을 번역 게재하고자 한다. 이달에는 제1장 연삭가공의 기초 게재를 시작으로 11월호에 이어서 나머지 2,3,4장 교육과정내용을 게재할 예정이다.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.30-35
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• 2010

As of today, Frequency Hopping techniques are widely used for over-channel interference and anti-jamming communication systems. In this paper, analysis the performance of robustness on the focus of some general jamming channel. In FH/SS systems, usually SFH(Slow Frequency Hopping) and FFH(Fast Frequency Hopping) are took up on many special communication systems, the SFH, FFH are also combined with a channel diversity algorithm likes NED(Normalized Envelop Detection), EGC(Equal Gain Combines) and Clipped Combines to overcome jammer's attack. This paper propose Adaptive-NED and shows A-NED will be worked well than the others in the some general jamming environments.

• Journal of the Semiconductor & Display Technology
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• v.10 no.3
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• pp.35-42
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• 2011

This paper describes the characteristics of high speed grinding and the influence of wheel surface speed V and a grindability of the grinding materials. The various fine ceramics pieces was ground by metal and vitrified bonded diamond wheel. The surface roughness of fine ceramics(Zirconia($ZrO_2$), Silicon Carbide(SiC), Silicon Nitride($Si_3N_4$), Alumina($Al_2O_3$)) decreases from $0.05{\mu}m(R_{max})$ to $0.025{\mu}m(R_{max})$ when the wheel speed at grinding point increases the wheel speed. Relation between the temperature at grinding point and surface roughness was linear. Abrasive jet machining(AJM), a specialized from of shot blasting, is considered one of the most helpful micro machining methods for hard and brittle materials such as glasses and ceramics by constant pressure grinding.

• Tribology and Lubricants
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• v.27 no.1
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• pp.7-12
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• 2011

Interest in advanced machining process such as AJM(abrasive jet machining) and CMP(chemical-mechanical polishing) using micro/nano-sized abrasives has been on the increasing demand due to wide use of super alloys, composites, semiconductor and ceramics, which are difficult to or cannot be processed by traditional machining methods. In this paper, the effects of pressure, wafer moving velocity and fluid viscosity were investigated by 2-dimensional finite element analysis method considering slurry fluid flow. From the investigation, it could be found that the simulation results quite corresponded well to the Preston's equation that describes pressure/velocity dependency on material removal. The result also revealed that the stress and corresponding material removal induced by the collision of particle may decrease under relatively high wafer moving speed due to the slurry flow resistance. In addition, the increase in slurry fluid viscosity causes the reduction of material removal rate. It should be noted that the viscosity effect can vary with the shape of abrasive particle.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.367-373
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• 2014

Surface texturing is a machining process on the surface to give engineering functions. The representative process of the surface texturing is lotus effect to give hydrophobic property by the lithography and chemical etching, which is the bio mimic from the nature. Surface texturing can be manufactured by a lot of processes, in particular using mechanical method such as a precise diamond turning, grinding, rolling, embossing, vibrorolling, and abrasive jet machining (AJM). Among them, the grinding process is notable in terms of the wide range of texturing area and fast processing time. The patterning by grinding is done by the grooved grinding wheel on the work piece. In this case, the pattern shape is determined by the grinding conditions as well as the wheel dressing conditions. In this paper, experimental study on the pattern shapes were done and provide the feasibility in use for the large area patterning.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1632-1642
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• 1992

When a blind hole of small diameter is drilled in the field of residual stress, strain relieved around the hole is function of magnitude of stress, patterns of stress distribution and hole geometry of diameter and depth. Relieved strain coefficients can be calculated from FEM analysis of relieved strain and actual stress. These relieved strain coefficients make it possible to measure residual stress which vary along the depth in the subsurface of stressed material. In this study, the calibration tests of residual stress measurement are carried out by drilling a hole incrementally on the cantilever or on the tensile test bar. Residual stresses can be determined from measured strains around a shallow hole by application of power series method. For the sake of reliable measurement of residual stress, much efforts should be done to measure relieved strains and hole depth more accurately comparing with conventional procedures of gage subject to the external load. Otherwise linear equations converting strains into stresses may yield erratic residual stresses because of ill-conditions of linear equations. With accurate measurements of relieved strains, residual stress even if varying along the depth can be measured. It is also possible to measure residual stress in the thin film of material by drilling a shallow hole.