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.

방사성동위원소를 이용한 위장관 출혈의 진단

이길우 대한영상의학회 1985 대한영상의학회지 Vol.21 No.2

The diagnosis of acute or chronic GI bleeding and the localization of bleeding site is important clinically. GI bleeding localization has been done with contrast angiography. However, dut to its invasivness & limitation, radionuclide angiography is being widely applicated recently. We have studied in 12 cases of surgically & clinically confirmed GI-bleeding lesion with Tc99m PHYTATE & Tc79m BLOOD POOLING AGENTS. Now we report the significance of radionuclide angiography for detection of GI bleeding in conjugation with clinical history & contrast angiography.

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.

Reye 증후군의 뇌 전산화단층촬영 소견

이길우 대한영상의학회 1990 대한영상의학회지 Vol.26 No.5

We present here the CT findings in 10 patients with Reye syndrome. Acute finding is diffuse cerebral swelling with or without parenchymal low density. The cerebral swelling gradually changed to atrophy. The parenchymal low density predisposes in Lt temporoparietal area. Contrast enhanced CT scan showed no additional finding, except 1 case. The hemorrhagic infarction which has not been reported previously was seen in 1 case and resulted in the most prominent sequela. The sequelae were developed in all atrophic cases. So, the brain CT may be useful in monitoring cerebral swelling, determining treatment plan in acute stage, and in presuming prognosis and sequelae on follow up CT.

상부소화관 협착환자에서 풍선 카테터 확장의 결과

이길우 대한영상의학회 1990 대한영상의학회지 Vol.26 No.6

Balloon catheter dilatation of upper gastrointestinal strictures is an accepted mode of therapy. the authors report the balloon dilatation in 11 consecutive patients. The lesions treated included 10 bengn strictures, and 1 esophageal cancer. Esophageal balloons were ranged form 2mm in diameter, 4cm in length, to 30mm in diameter, 8cm in length. Inflation was held for from 30 to 60 seconds and then repeated two or three times during each session. The balloons were inflated to pressure of form 2 to 12 atmosheres. There were from 1 to 13 dilatations. Two esophageal perforations were occurred in one esophagitis patient and other lye stricture patient. Two perforations were not required any surgical repair. All dilatations were performed without anesthesia. All strictures were responded immediately to dilatation. Prolonged course of treatment were needed with chronic severe esophagitis, lye structure, gastrojejunostomy with chemotherapy, as a result, all patients. except esophageal cancer, could take regular diet after balloon catheter dilatation,. Balloon catheter dilatation of upper gastrointestinal stenosis was effective & safe. It should be considered before other methods of treatment applicable.

탈선비장의 염전

이길우 대한영상의학회 1988 대한영상의학회지 Vol.24 No.6

The wandering spleen is a rare anomaly(1). Preoperative diagnosis is difficult unless serious complications develop(2). Torsion of the spleen is one of the less common surgical conditions(3) This report documents a typical case of torsion of the wandering spleen with review of radiologic findings and literatures. the patient was 8-year-old female whose complaints were epigastric pain and vomiting. A huge abdominal mass was palpated in right midabdomen. A plain radiograph of the abdomen demonstrated a large soft tissue mass which was located at right midabdomen transversely. A barium enema showed the mass to be extrinisc to the colon with inferior displacement of the midportionof transverse colon. The sonography revealed a spleen-shaped solid mass in midabdomen and absence of the splenic echo in its normally identifiable position. As the results of sonography the wandering spleen was strongly suspected. A Tc-sulfa colloid scan revealed a normal liver with the absence of splenic uptake presumably secondary to twisting of the splenic pedicle with occlusion of the vascular supply. An abdominal CT scanning revealed the enlarged and infarcted spleen in anterior midab-dominal cavity and the gas distensions of the stomach & the splenic flexure area. Angiography was the most definitive diagnostic modeality in the evaluation of wandering spleen. Celiac angiography revealed an enlarged wandering spleen with no evidence of torsion. The splenic artery was elongated and displaced to right side which arose from common hepatic artery. Left gastric artery was also stretched. Surgery was done. The spleen was 12x9x5cm in size and discolored to dark reddish. The splenic vessels were dilated with twisted splenic vascular pedicle. A splenectomy was performed. The interstitial hemorrhage of spleen was reported on pathologic finding.

복부내 농양의 초음파소견

이길우 대한영상의학회 1985 대한영상의학회지 Vol.21 No.5

With the recent development of real time technology, ultrasound is now uniquely well suited for the detection of abdominal abscess. The high accuracy of ultrasound in detecting abdominal abscess has been widely documented, also. The typical ultrasound appearance of an abscess is that of a fluid collection with diffuse, weak internal echos, representing the internal contents. Authors analyzed echogenicity and regularity of the abscesses in surgically and pathologically confirmed intra-abdominal abscesses, 38 cases except intra-abdominal organ abscesses. 1. 38 cases consist of 30 intra-abdominal abscesses, 4 pelvic abscesses, 4 retroperitioneal abscesses. 2. Numbers of the abscesses are 32 single and 6 multiful. 3. Echgenicity consist of 9 cystic, 14 semisolid, 6 solid, 9 mixed. 4. Mean size of abscess is 6$\times$5 cm in single, but not measureable in multiful. 5. Abscess wall have relatively irregular inner wall(28 cases) and relatively regular outer wall(21 cases) in our cases. Con equently, echogenicity of the abscess is variable. But, relatively semisolid. Abscess have relatively irregular inner wall and relatively regular outer wall on ultrasonogram.

파인-세라믹스의 기계가공에 대한 연구

李吉雨 홍익대학교 산업기술연구소 1999 産業技術 Vol.9 No.-

To expand the application of fine ceramics to machine parts, a proper machining method is indispensable, which can satisfy severe demands for dimensional accuracy, geometrical accuracy and surface integrity of ceramics parts in the same manner as machining of metal. then the processes of deformation and fracture of fine ceramics, which is very hard and brittle, must be clarified to establish an available machining method. This report made clear the processes of deformation and fracture of fine ceramics in a transitional cutting. Experiments were carried out under conditions in which fine ceramics was cut at very small depth of cut using sintered diamond tools. The experiments give evidence that cutting process of fine ceramics are characterized by remarkable phenomena such as rubbing. Indenting, swell-up and crack initiation, large-scale fracture, and that these phenomena occur corresponding to interference depth of cutting edge. Also some factors influencing these phenomena are discussed. Key words : ceramics, machining, surface formation, transitional, rubbing, indenting, swell-up crack initiation, fracture,

공구의 손실을 고려한 최적공구 교환시기의 설정

李吉雨 홍익대학교 산업기술연구소 2001 産業技術 Vol.11 No.-

This paper describes determination procedure of optimum tool changing period which minimizes the loss of tool cost due to early tool changing and the loss of defectives, or nonconforming articles, produced by delayed tool changing, together with machining and material cost. For stochastic approach, a tool-life model is built-up by adding to a progressive wear process according to Taylor-like equation a sudden-death mechanism corresponding to macroscopic fracture. The model is developed as a fuction described by long-normal distribution and exponential distribution. Morcover, the distribution of defective produced by failed under facture or wear can be obtained in similar way. Effects of several factors connected with machaning economics on optimum solution are then investigated. The factors are failure rate, work material cost, cutting length, overhead and laber cost, and tool cost. The optimum tool changing periods given under various conditions are compared with the solution given by deterministic approach. In many illustration, the optimum tool changing periods come to shorter than those by determinstic approach except the case of high tool cost.

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.