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이철구(C.K. Lee),이우람(W.R. Lee),박철양(C.Y. Park) 한국생산제조학회 2011 한국생산제조학회지 Vol.20 No.5
The current establishment of city gas piping polyethylene (PE) tube used as bonding state or part of the health or safety of fusion is very important. A part of these fusion methods to determine the soundness of the short-term trials and long-term tests can be largely classified. Typical tests include short-term strength, tensile strength, impact strength, compressive strength, resiliency and compression. Polyethylene (PE) pipes installed in the domestic terms of overall penetration rate of 45% has been used. However, polyethylene (PE) pipes have reliability problems, and these occurs mostly in part by defective welding. Therefore, the test is necessary for safety. Non-destructive methods (ultrasonic testing) are difficult to be used. Therefore, Polypropylene copolymer (PP-C), polypropylene homopolymer (PP-H), and polyethylene (PE) pipe are used. Fusion of thses materilas is necessary in these field however, its technical, and basic research has not been studied well. In this research, short-term strength of welding parts, its tensile strength, hardness, fatigue, and microstructure have been analyzed to find the optimum process conditions to improve mechanical properties.
자기장 영향에 따른 냉연압연 강판의 파이버 레이저 마이크로 접합 공정
이철구(C.K. Lee),이우람(W.R. Lee) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.3
We have studied on welding dissimilar materials of Carbon steel SCP1-S by using laser beam. In this research we have performed some experiments to know the possibility of welding dissimilar materials using laser beam and magnetic fields by adjusting the power output of 35W laser. Other conditions of the experiments were as follows : the welding speed was varied in the range 10 m/min nitrogen gas was used as shield gas, the flow value of shield gas was ranged 10 L/min. In order to ascertain of the welded surface, we have done the tensile strength testing, the hardness testing and the microscope observation. As a result, we have found that tensile strength was the highest at the condition of the welding speed of 10mm/s, the flow value of 10 L/min, the gap of two materials 0, and the use of nitrogen gas. Above testings have also showed that the tensile strength was generally satisfactory since the penetration of welding was almost complete due to the thinness of the materials. In addition, the formation of the welded area was excellent when it had the highest tensile strength.
하영철(Y. C. Ha),허재영(J. Y. Her),이철구(C. G. Lee),이강진(K. J. Lee),안승희(S. H. An),정종태(J. T. Chung) 한국유체기계학회 2000 유체기계 연구개발 발표회 논문집 Vol.- No.-
The flow computer named Kogas I has been developed for measuring high flow natural gas. The developed model is classified as individual type in order that one flow computer covers one metering line. Nearly all of the functions are adopted similar to the foreign, commercial flow computer, and the merit of this flow computer is being able to apply for both orifice and turbine meters. The performance has been verified through the field test for 2 years.
박재원(J. W. Park),이철구(C. K. Lee) 한국도시철도학회 2014 한국도시철도학회논문집 Vol.2 No.3
To understand the basic principles of corrosion of the metal, it is essential to understand the corrosion resistance properties of stainless steel. The corrosion is a phenomenon that the metal structures react with the environment resulting in dissolving in the aqueous solution of the metal ion or the deterioration in the oxide or hydroxide. This corrosion is a spontaneous electrochemical reaction occurring at the interface in contact with the metal and the corrosive environment; the metal structures are eventually destroyed because they lose the inherent mechanical properties of themselves. Therefore, the life of the metal structures that is used in a corrosive environment is determined by the rate of corrosion reaction. It is important that understanding the corrosion properties of stainless steel and selecting the best alloy for the given environment to determine the life of the structure. In the reliability evaluation of the stainless steel welds, the regulations on the radiation exposure are getting stricter. Computer radiographic testing can reduce the amount of exposure that is about 1/2 to 1/80 compared to the conventional testing method. The aim of this study was to examine the reliability evaluation compared to stainless steel welds by radiographic testing and film welding process computer systems and conventional manual ultrasonic testing. As a result, there was no discontinuity on the reliability on the weld zone of built-in stainless steel material.
연탄(煉炭)가스 중독자(中毒者)의 생활환경(生活環境)에 관(關)한 역학적(疫學的) 연구(硏究)
김인달,윤덕로,최용어,윤인재,이철구,양요환,Kim, In-Dal,Yun, Dork-Ro,Choi, Y.O.,Yun, I.C.,Lee, C.K.,Yang, Y.H. 대한예방의학회 1972 Journal of Preventive Medicine and Public Health Vol.5 No.1
Carbon monoxide poisoning is one of the most serious health problems in Korea, because we have been encountered with the highest incidence of CO poisoning in the world due to the unique heating system in home called 'ondal'. We opened Hyperbaric chamber unit in the Seoul National University Hospital last Jan, 1969. We have treated 848 patients as of Sept. 30., 1972, around 44 months period. We collected the informations on the environmental conditions of the place where CO intoxication actually occured by filling up the questionaire from 505 patients. The following findings were obtained. 1. Age distribution showed that the highest incidence was found in the younger age group between age of 10 to age of 29 in both sex. 2. Sex ratio of the patients was 1:1.14. 3. The socio-economic level of the patient was relatively low. 4. Housewife & housemaid were the major victims of the intoxication in the female patients & in the case of the male patient, occupational backgrounds were diverse. 5. Many patients from the middle class experienced the intoxication by sleeping at newly built room. 6. Many intoxication has been occured in the structure of houses where communicating doors are existing between living room & kitchen. 7. All findings obtained taught us again that CO poisoning is the serious by-product of the national fuel policy which put emphasis on the use of coal & socio-economic status is a very important parameter in this hazards.
레이저 용접 공정 시 발생하는 잔류 응력에 저감 방법에 대한 연구
이우람(W. R. Lee),이철구(C. K. Lee) 한국도시철도학회 2014 한국도시철도학회논문집 Vol.2 No.4
The demand for the increase of the welding quality such as optimized welding process control, The study on the prediction and evaluation of residual stress among the research to improve the quality of laser welding process and increasing the mechanical property are not yet satisfied compared with their importance. The simulated results could be applied to estimate a peening effect, when a different confinement was used in the laser shock peening process. The residual stress could be formed by the depth of the proposed method of reducing the residual stress is performed in the optimal condition. The welded structures and products during the production process increase the mechanical property of repeated stress, which could be expected to extend the fatigue life of the structure.
철도 차량 운송용 압력용기 클래드강의 용접 공정에 따른 신뢰성 평가
박재원(J. W. Park),이철구(C. K. Lee) 한국도시철도학회 2014 한국도시철도학회논문집 Vol.2 No.4
Due to the recent tightening of regulations on environmental issues and improvement in the performance and efficiency of marine structures, pressure container made of stainless clad steel is being constructed in the upper structure. Austenitic stainless steel is excellent in its mechanical nature and corrosion resistance, and is thus used in various conditions in a wide range of temperatures from extremely low to high. In this research, butt welding of clad steel is carried out with FCAW, SAW, and SMAW with the welding process as a variable, in order to find the optimum welding process for clad steel comparing the strength, reliability, and structure of the welded part. This research concludes that Flux-Cored Arc Welding (FCAW) demonstrates the highest reliability in the production of pressure vessel for railway vehicles as a result of the reliability test of the welded part in different welding processes.