Advanced Indentation System을 이용한 연성 파괴인성 평가식의 모델링

주장복,이정석,심홍석,이승건,권동일 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.1

Fracture properties of various structural steels were determined non-destructively using the advanced indentation system (AIS), which is developed on the basis of continuous indentation technique. In this study, conventional critical strain model was modified to predict the ductile fracture toughness from the AIS data. In deriving the ductile fracture toughness model, fracture strain and characteristic length were estimated using the stress triaxiality and the work-hardening exponent. AIS tests were conducted on carbon steels, stainless steels, aluminum alloys and copper alloys. For all these materials, the results of indentation test were compared to those of the standard fracture toughness test methods, which shows that the present analysis can predict successfully the ductile fracture toughness of structural steels.

지지막을 이용하는 액막 추출기 내에서 아연 이온의 이동

주창식,이석희,이민규,홍성수,하홍두,정석기 한국환경과학회 2000 한국환경과학회지 Vol.9 No.2

For the purpose of development of a liquid membrane permeator which separates metal ions from aqueous solutions continuously and effectively, a continuous membrane permeator with the membrane solution trapped between extraction and stripping phases by two micro-porous hydrophilic films was manufactured. Experimental researches on the separation of zinc ion from aqueous solutions were performed in the liquid membrane permeator with 30 vol % D_2EHPA solution in kerosine as liquid membrane. As results, the liquid membrane permeator separates zinc ion from aqueous solutions continuously and effectively in the wide range of operating conditions. A simple mass transfer rate model using equilibrium constant of the extraction reaction for the system used were proposed, and the model was compared with experimental results of separation of zinc ion in the permeator. And the effects of operating factors, such as space time, pH of extraction solution, extraction temperature, on the separation rate of zinc ion in the permeator were experimentally examined.

서울시 역세권 주차장의 운영 합리화에 관한 연구

고주연,금기정,김현정,김현주,홍영식 明知大學校 産業技術硏究所 1995 産業技術硏究所論文集 Vol.14 No.-

In this study, we study about park and ride facilities at subway station in seoul, since we have perceived that park and ride facilities at subway's station's serious problem on its operation and usage. We practiced the interviews and transfer rate survey so found these problems of operation usage problem, spatial utilization, private park and ride facilities. Through the analysis of these problem we propose the adequate alternatives and we hope that our study contribute operation rationalization of park and ride facilities at subway station.

노인의 Helicobacter pylori 재균율

박주상,홍원선,이영수,이은주,명승재,정훈용,양석균,김진호,민영일 대한노인병학회 2000 Annals of geriatric medicine and research Vol.4 No.3

灌漑用 小溜池의 內容積에 關한 硏究

宋錫銀,周栽洪,李裕根 진주산업대학교 1982 論文集 Vol.20 No.-

Obtained results for study as above are as follows. 1. The unit depth of water of the present state of reservoirs was below 160 millimeter on the average. 2. The frequency of drought happened one time per three years. 3. The ratio of a well irrigated paddy field was less than 40%. 4. When the unit depth of water of reservoirs is at least 300 millimeter, it is regarded as a well irrigated paddy field. 5. If possible technically, when we raise the present state of dam height of reservoirs more than 1 meter, we can store up the irrigation water for somehow 20 days.

탄산가스를 이용한 아아크 용접에서 국소배기설비의 제어 속도가 용접성에 미치는 영향에 관한 연구

김병철,홍석주,김기형 조선대학교 동력자원연구소 1996 動力資源硏究所誌 Vol.18 No.2

It was studied the effects of control velocity of local exhaust installation in CO_2-Gas Arc Welding by using the SS41 in the process of car boby production. The properties of the specimens after welding were observed and analysed It was concluded as follows : (1) The trensile strength and tensile load was apparently lowered when the control velocity was above 1.0m/sec (2) The hardness was increased when the control velocity of hood was above 1.0m/sec in the welede metal. (3) When the control velocity was above 1.om/sec, the base metal was not completely melted. (4) In the bending test when the control velocity was above 1.0m/sec, weld zone was brittle. (5) When the control velocity was above the 1.0m/sec, the shielding effect was lowered and weld zone was found to be defective.

油膜의 衝突 效果에 對한 硏究

河鈺男,洪錫柱,金炳哲 조선대학교 동력자원연구소 1988 動力資源硏究所誌 Vol.10 No.1

Oil Film can not reduce the error in the course of manufacturing process but also soften the sliding contact, so it can increase the efficiency of the machines. In many case of cold rolling there are impacts and the oil film influences on the structure of the surface. In this manner the influences of the oil film under impact on the flates were studied and the following conclusions were obtained; 1) In the case of being oil film and not being oil film, there were differences in the central area of surface. 2) In the case of not being the oil film the structure of the surface was flated and being ol film the structure did not change. 3) When the oil film is broken by the impact the metal begin to contact and when the viscosity is thick, it hard to breaking. 4) The higher the viscosity is the longer the contact the time of metal.

복합적층원통셸의 좌굴거동

원종진,이종선,홍석주 한국공작기계학회 1997 한국생산제조학회지 Vol.6 No.2

The objective of this study is to investigate effects of prebuckling on the buckling of laminated compostie cylindrical shells. Both axial compression and lateral pressure are considered for laminated composite cylindrical shells with length to radius ratios. The shell walls are made of a laminate with several symmetric ply orientations. The study was made using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered.

면역성 혈소판감소성 자반증 및 호중구감소증을 동반한 궤양성 대장염 2예

남승우,양석균,김진천,지현숙,김우건,정훈용,박주상,홍원선,민영일 大韓消化器病學會 1999 大韓消化器病學會誌 Vol.33 No.1

small artificial defect(미소인공결함)

이승용,정재강,홍석주 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1

본 실험에서는 자동차의 전륜 구동축재(S43C, S50C)에 대해서 미소 원공결함을 가공한 비열처리재와 고주파열처리재의 피로시험편에 회전굽힘응력을 가하여 피로강도와 피로크랙의 발생 및 전파거동에 관하여 실험한 결과 다음과 같은 결론을 내렸다. 비열처리 S43C재 및 S50C재의 피로한도는 각각 98.1MPa, 107.9MPa이었고, 열처리재의 경우 각각 147MPa, 156MPa로서 열처리재는 비열처리재보다 약 50Mpa 증가하였다. 응력이 피로한도의 110%에서 120%로 증가하는 경우 비열처리인 S43C재 및 S50C재에서 피로수명의 감소율은 각각 약 49%, 약 45%였으며 또한 열처리재의 경우는 각각 약29%, 약 22%로서 비열처리재보다 열처리재가 피로수명 감소율이 낮게 나타났다. 평활재에서 표면 미시크랙의 발생은 비열처리재인 S43C 및 S50C에서는 수명비(N/Nf) 0.2정도에서 처음 관찰되었으며, 동일한 수명비에서 관찰된 미시크랙의 수는 S43C가 많았고, 평균 크랙길이는 S50C가 길었다. 피로크랙길이와 파단수명비의 관계 log(2a)=A+B(N/Nf)식에 본 실험재료를 적용한 결과 응력수준에 관계없이 잘 일치하였다 In this paper, an experiment to investigate the behavior of fatigue crack propagation in induction hardened structural carbon steel(S43C, S50C) with artificial defect are conducted by the rotary bending fatigue test in the room temperature. The summarized results are as follows: The fatigue limits obtained from experiments of as-received S43C and S50C were 98.1MPa and 107.9MPa respectively. The fatigue limit of heat-treated materials were 147MPa and 156MPa respectively. It means that the heat-treated specimens showed about 50MPa higher fatigue limits than the as-received material. When the applied stress was increased from 110% to 120% of fatigue limit, the decreasing rate of fatigue life was around 49% and 45% respectably in the as-received S43C and S50C, in case of the heat-treated materials, the decreasing rate of fatigue life was around 29% and 22% respectively. It means that the heat-treated materials had lower decreasing rate of fatigue life than the as-received materials. The initiation of surface micro crack was observed at 0.2 of fatigue life ratio in as-received S43C and S50C. The number of micro cracks in S43C were more than that of S50C, but the average crack length in S50C was longer than that of S43C at the same fatigue life ratio. Experimental results obtained from fatigue test were evaluated with the equation log(2a)=A+B(N/Nr). The relationship between crack length and cycle ratio showed a good agreement to the experimental results.