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공구내부 냉각법에 의한 스테인레스강의 공구수명 향상에 대한 고찰
李吉雨 弘益大學校 産業技術硏究所 2005 産業技術 Vol.15 No.-
When stainless steel, a difficult work material, is cut, cutting forces increase and cutting temperature rises significantly. Consequently, the tool of life of high-speed steel becomes markedly short. To reduce the cutting temperature, the tool is cooled internally with water, and to reduce cutting forces, high-velocity cutting oil is applied. With the method of cooing and lubrication technique tool life becomes far longer, compared with that in ordinary cutting. Accordingly, this procedure would be very effective for cutting other difficult work materials.
李吉雨 홍익대학교 산업기술연구소 2000 産業技術 Vol.10 No.-
In-process detection of tool wear haven been attempted for adaptive control or unmanned operation of machine tools This paper propose a model based on the cutting data a by tool with flank wear land. In the model, stresses on flank wear land are related to the shear stress onthe shear plane. The model and energy method enable to predict the cutting force ratios (axial force to tangential force, radial force to tangential force) with the increase of tool flank wear land in turning. It is clarified that a resolution of the increase of the flank wear land by cutting force ratios is 0.025∼0.35㎜/%. The analytical method is applied to set criterion for sensing of tool wear by means of the cutting force ratios. The criterion set by analytical method is available to detect and control tool flank wear land.
성인에서 그레이브스병과 동반된 가성부갑상선기능저하증 1예
이길우,김재훈,이강원,김사일,홍상모,김동선,최웅환,안유헌,김태화 대한내분비학회 2010 Endocrinology and metabolism Vol.25 No.3
Pseudohypoparathyroidism is a rare disease that is characterized by target cell resistance to the effects of parathyroid hormone and this disease is classified into various types depending on the phenotypic and biochemical findings. The patients with pseudohypoparathyroidism present with the clinical and biochemical features of hypoparathyroidism, but they have an increased serum level of parathyroid hormone. We experienced a case of pseudohypoparathyroidism in a 24 years old woman who had Graves’ disease at that time. She had hypocalcemia, hyperphosphatemia, an elevated serum parathyroid hormone level and a normal urinary basal cyclic AMP(adenosine monophosphate) level. She also had a normal phenotypic appearance. Therefore, she was classified as suffering with pseudohypoparathyroidism type II. The clinical and laboratory abnormalities were improved by calcium supplementation in addition to vitamin D. To the best of our knowledge, this is the first case of pseudohypoparathyroidism combined with Graves’ disease in Korea.
기관평가제도 운영의 영향요인에 관한 연구과학기술계 정부출연연구기관을 중심으로
이길우 한국기술혁신학회 2005 기술혁신학회지 Vol.8 No.S
The purpose of this paper is to seek out the problems influencing on the operation of Institution Evaluation(IE) in Korea and suggest a better way for the evaluation based on the findings, expecially focusing on Government Research Institute(GRIs) in the field of Science and Technology. Unlike previous studies on IE of GRIs, this research is more oriented toward actual practices than design and theories of IE. Three categories are 1) purely system aspect, 2) system-operation aspect, and 3) environmental aspect. These three categories are classified into eight subcategories: 1) the legal support and the legally enforceable provision, 2) the target area of evaluation, 3) the means and process of evaluation, 4) the criteria and indices for evaluation, 5) the expertise of evaluators, 6) the use of evaluation findings, 7) GRIs' support for IE, and 8) public support for IE. Summing up the findings of this study, the main factors that hamper the successful operation of the existing IE of GRIs in the field of Science and Technology was illuminated and the better way for the operation of IE was suggested.
李吉雨 홍익대학교 산업기술연구소 1994 産業技術 Vol.3 No.-
The tool material is the most important factor in the cutting process of brittle materials. Cutting tools are subject to damages by high stress, adminish shock, and wear. Therefore, the relative hardness of toll material to the workpiece is one of the necessary conditions to keep the tool tips in shape. Also it is affected by mechanical, physical, and chemical properties of workpiece and tool material. It is the purpose of this study to find the condition for the high machinability of the lathe turning process of machinable ceramics. When superhard too K was chosen as the tool material, the machingcondition were found v=50m/min, f=0.025㎜/rev, and t=0.2㎜. Alos the optimal condition for CBn tools were found v=100m/min, f=0.025㎜/rev, and t=0.1㎜. The best surface roughness after the machining was established forthe chamber angle of -150 while other conditions were fixed. The cutting of high strength material was possible with large nose radius bite.
生産性을 考慮한 切削加工에 對한 最適切削條件의 自動選定에 關한 硏究
李吉雨,金泳祥 홍익대학교 산업기술연구소 1996 産業技術 Vol.6 No.-
In recent years machining turns to flexible manufacturing. Industry in machining requires to increase machining productivity and to reduce costs. To adapt this trend it is necessary to optimize machining condition Even though many researches in this are introduced various way to set the optimal condition, still there are not enough. Therefore this research was done to select the optimal cutting condition for industry, and to develope the computer program to select the optimal cutting condition automatically. Also, this program was applied to many companies, and compare costs per minute. The results of this research will contribute to increase machining productivity of various companies with the automatic selection of optimal cutting condition.