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Si 첨가 고탄소강의 인장 성질에 미치는 패턴팅 조건의 영향
이준범,이상윤 ( J . B . Lee,S . Y . Lee ) 한국열처리공학회 1993 熱處理工學會誌 Vol.6 No.2
Isothermal transformation behavior during patenting and variations of microstructure and tensile strength of patented wires were investigated in Si-added high carbon steel. The TTT curves of the steels were made for two different austenitizing temperature. As the salt bath temperature was increased, the observed microstructures were bainite at 450℃, the mixture of bainite and pearlite at 500℃, and to pearlite at 600℃, The tensile strength of patented wire exhibited the highest value when the structure was pearlite, while the bainitic structure showed the lowest.
Co2레이저 비임을 이용한 표면경화 처리중 형성된 AISI 4140의 잔류응력에 관한 연구
박근웅,이준범,한유희,이상윤 ( K . W . Park,J . B . Lee,Y . H . Han,S . Y . Lee ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.4
This study has been performed to investigate into some effects of power density and traverse speed of laser beam on the microstructure, hardness and residual stress of AISI 4140 treated by laser surface hardening technique. Optical micrograph has shown that large martensite and a small amount of retained austenite in outermost surface layer and fine lath martensite in inner surface hardened layer are formed under the condition of a given power density and traverse speed. Hardness measurements have revealed that as the power density increases at a given 2.0m/min of the traverse speed, the maximum hardness values of outermost surface hardened layer is increased from Hv=635 to Hv=670. X-ray analysis for residual stress has exhibited that low compressive residual stress values are obtained in center point of the cress section of surface hardened layer with in mid point between the edge and the center point, about 1.5㎜ from the center point, due simply to a difference in self-quenching rate. It has been shown that the higher the power density at a given traverse speed and the olwer the traverse speed at a given power density, the more the compressive residual stress values are increased due to an increase in the input heat of laser beam.
물리적 처리가 우모분의 단백질 함량과 소화율에 미치는 영향
김영붕,이준범,성기승,이남형 ( Y . B . Kim,J . B . Lee,K . S . Sung,N . H . Lee ) 한국축산학회 1998 한국축산학회지 Vol.40 No.1
These studies were carried out to investigate the effects of physical treatments of feather on improvement of digestibility. Raw feather consisted of 83.3% protein, 6.6% lipid, 9.0% moisture and 0.6% ash. Feather meals were composed of 72.25∼80.68% protein, 5.08∼22.29% lipid, 4.04∼10.06% moisture and 2.46∼4.81% ash depending upon producers. Pepsin digestibility of the feather meals were ranged from 51.92% to 74.0% by companies(P c 0.05). Various grinding conditions of the raw feather did not affect pepsin digestibility. However, the digestible protein content of the feather meal after steaming was increased to 76.58% compared to the raw feather. The digestibility of feather meal was increased with the increase temperature and time. So, the optimal condition of processed feather meal was 130℃ for 240 min with steaming and ball milling. The digestible protein content from this condition was 80.22%. In electrophoresis the bands of the feather meals showed small peptide fragments of feather by steaming. Molecular weights of the feather meals were below 14,000Da. Therefore proteins in feather were able to convert their keratinous structure to more digestible form under the high-temperature and the long-time condition.
자동차용 Return Spring재의 침탄질화 및 침질탄화에 따른 경도와 토크값의 변화
이상화,이준범 東亞大學校 大學院 1997 大學院論文集 Vol.22 No.-
This paper has been performed to investigated into some effects of torque value on endurance test, hardness and microstructure of return spring by carbonitriding and nitrocarburising. Hardness measurements have revealed that the range of hardness value is HRC30 to HRC38 of return spring, maximum hardness nalues of surface hardened layer is V450 to HV500 by carbonitriding and HV750 over by nitrocarburising. Torque value of surface hardened return spring is lower than that non heat treated return spring.
중탄소 Boron 강의 가스침질탄화처리에 의해 형성된 화합물층의 마모특성에 관한 연구
이상윤,이해우,조효석,이준범,박기원,오도원 한국열처리공학회 1999 熱處理工學會誌 Vol.12 No.2
The study on the wear characteristics of compound layers formed during gaseous nitrocarburising in the medium carbon boron steels and the plain carbon steel has been carried out by using a pin-on-disc type wear test machine under the oil lubricating condition at room temperature and by varying applied loads, sliding speeds and wear distances. Values of friction coefficient measured at the sliding speed of 0.4m/sec under the oil lubricating condition have been shown to decrease considerably with increasing applied load and become gradually a constant value as load is increased to a higher value, showing that the transition load for friction coefficient appears at an applied load of 247.2N. The length and volume wear rates of compound layer have been revealed to relatively constantly increase, also showing that the wear life per unit thickness of compound layer turns out to be superior as porous layer has a denser and thinner appearance. As the sliding speed increases during wear test performed by varying sliding speed at a load of 63.2N under the oil lubricating condition for medium carbon boron steel nitrocarburised in gas atmosphere, the wear rate has been found to increase, the friction coefficient to decrease and the wear life per unit thickness of compound layer to decrease considerably.