• 소음진동
• /
• 제9권5호
• /
• pp.1050-1057
• /
• 1999

The existence of clearance at the link joint of a machine is inevitable for assembly and mobility. During the cyclic operation of a machine, rapid changes of the direction and magnitude of connection forces cause momentary loss of contact between the pin and the bushing at the link joint. Contact loss at the clearance joint gives rise to undesirable impact. The impulsive force affects on the performance of the machine, and leads to excessive vibration, noise and faster wear in the connecitons. In this paper, experiment and theoretical analysis were carried out for the variation of crank speed and clearance size. The link mechanism employed in this investigation was newly designed to check the effects of parameter changes on the occurrence of contact loss and on the magnitude of the impact force. The contact loss and impact position were calculated with various driving conditions.

• 열처리공학회지
• /
• 제11권1호
• /
• pp.62-72
• /
• 1998

High carbon steel is used for rails due to the excellent wear resistance, however the welding of high carbon steel is more difficult than that of mild steel owing to the high hardenability and sensitivity to cracking at the weldment. In this study, the impact toughness and cracking behavior of a rail weldment were evaluated as function of preheating temperatures. Impact toughness were more excellent in the specimen welded with preheating temperature above $250^{\circ}C$ than that below $100^{\circ}C$, and cracks were not detected in the specimen welded with preheating temperature above $250^{\circ}C$.

• 한국주조공학회지
• /
• 제19권1호
• /
• pp.84-90
• /
• 1999

In this study, CV cast iron was reverse transformed to produce harder second phase surrounding graphite nodules, and then the microstructure and related mechanical properties of the reverse transformed CV cast iron were investigated by using optical microscopy and by carrying out hardness, tension and impact test. The formation of hard second phase surrounding graphite nodules increased the hardness in CV cast iron. The marked increase in hardness was resulted from the formation of martensite surrounding graphite nodule. It is expected from these results that the formation of martensite surrounding graphite nodule would improve the wear resistance of CV cast iron. The formation of both martensite and pearlite surrounding graphite nodule improved the tensile properties. Impact properties were decreased with increasing the volume fraction of hard second phase. However, the reduced impact properties could be recovered through phase transformation of martensite into pearlite and sorbite by tempering.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.484-493
• /
• 2006

This paper is presented the test results to evaluate the healthiness of the ballast in subway. The test includes the dynamic load test in servicing Line the screen classification test of aggregates and the wear test. From the results, the aspect and the property of the ballast are evaluated. The dynamic load tests the relationship between the deterioration of the ballast and the fluctuation of loads. The assesexplain sment of impact factor based on the field test results in a good property of test blocks is proposed.

• Journal of Welding and Joining
• /
• 제26권4호
• /
• pp.44-49
• /
• 2008

Generally, wear plate is steel plate having improved surface contact strength and impact strength by surface hardening which is welded using materials with good corrosion resistance, wear resistance and thermal resistance property. CFP GMAW(Compound Filler Plate Gas Metal Arc Welding) is the cladding method using GMAW with the CFP, which is bound with waterglass, on the substrate. It has advantages of reducing compound powder loss, uniform penetration, and preventing hardness decrease. To develope mass production technique of CFP GMAW process for production of high quality wear plate, the method for controling shallow penetration and increasing productivity is required. In this study, twin torch method applied to CFP GMAW process for increasing productivity. And the method was developed by controling penetration control, CFP dry time, gas formation flux and water glass concentration. As a result, applying twin torch method to CFP GMAW process was possible and high quality wide bead could be made without overlap joint.

• 한국주조공학회지
• /
• 제11권6호
• /
• pp.463-474
• /
• 1991

The effect of $0.01{\sim}0.10%$ Sb and Sn on the wear resistance of ductile cast iron was investigated. The hardness was increased with Sb to 0.10%, but the elongation and the impact value were decreased. The tensile strength was increased with up to 0.05% Sb, however decreased with $0.05{\sim}0.10%$ Sb. The hardness and the tensile strength were increased and the elongation was decreased with up to 0.10% Sn. The nodularity of graphite was decreased with above 0.08% Sb however Sn had no effect on that. When the maximum compressive stress was low ($42kg.f/mm^2$), the weigth loss was decreased with increased hardness and when that was high ($54kg.f/mm^2$ and $65kg.f/mm^2$), the weight loss did not depend upon the hardness. The pearlite stabilization with Sb and Sn increased with the wear resistance of ductile cast iron.

• 한국안전학회지
• /
• 제18권3호
• /
• pp.14-21
• /
• 2003

This study deals with the influence of ceramic coating on characteristics of friction and abrasion of aluminum allot(7075 T6) used in mechanical casting. In this research, frictional wear characteristic of ceramic coating materials such as $A1_2O_3$, $Si_3N_4$, SiC was investigated using aluminum alloy(7075 T6) and stainless 403 cast iron under room temperature and normal air pressure. The coating layer was observed using SEM. The conclusions are as follows: 1) Friction coefficients of $A1_2O_3$, SiC and $Si_3N_4$ are obtained 0.63 0.56 and 0.54 respectively. 2) Abrasion resistance of stainless 403 cast iron with $Si_3N_4$ is the best among the ceramic coating materials. 3) Abrasion mechanism of aluminum alloy(7075 T6) coaled with ceramic material and stainless 403 cast iron is caused by brittle fracture. 4) Coating the ceramic material on the aluminum alloy(7075 T6) can effectively increase the antiwear, impact properties, and corrosion resistance.

• Tribology and Lubricants
• /
• 제39권6호
• /
• pp.244-249
• /
• 2023

This paper presents a comprehensive analysis of the impact of surface roughness on the friction and wear properties of SUS 321, an austenitic stainless steel variant produced using the laser powder bed fusion (LPBF) technique, which is a prevalent additive manufacturing method. After the LPBF fabrication, the specimens go a heat treatment process aimed at alleviating residual stress. Subsequently, they are polished extensively to achieve a refined and smooth surface. To deliberately introduce controlled variations in surface roughness, an etching process is employed. This multi-step method encompassed primary etching in a 3M hydrochloric acid solution, followed by secondary etching in a 35 wt% ferric chloride solution, with varying durations applied to different specimens. A comprehensive evaluation of the surface characteristics ensued, employing precise techniques such as surface roughness measurements and meticulous assessments of water droplet contact angles. Following the surface treatment procedures, a series of friction tests are performed to explore the tribological behavior of the etched specimens. This in-depth investigation reached its peak by revealing valuable insights. It clarified a strong correlation between intentionally altered surface roughness, achieved through etching processes, and the resulting tribological performance of LPBF-fabricated SUS 321 stainless steel. This significantly advances our grasp of material behavior in tribological applications.

• 감성과학
• /
• 제20권3호
• /
• pp.97-108
• /
• 2017

본 연구의 목적은 스마트 피트니스웨어가 갖추어야 할 요건과 스마트 피트니스웨어의 수용 정도 및 기능 수요를 고찰하고, 이를 기반으로 퍼스널 트레이닝 효과 향상을 지원하는 피트니스용 스마트 스포츠의류의 상품기획 및 디자인 방향을 제시하는 것이다. 이를 위해 전문 피트니스 트레이너를 심층 인터뷰하고 그 응답 자료에 대해 범주분석을 실시한 결과 5개의 범주와 13개 주제어를 도출하였다. 또한 일반 소비자들을 대상으로 설문조사를 실시하여 스마트 피트니스웨어의 수용 정도와 상품개발에 필요한 기능 수요를 탐색하였다. 그 결과 전반적으로 인구통계학적 특성에 따른 차이보다는 운동의 관여도 및 운동관련 문화와 관련된 특성에 따라 스마트 피트니스웨어의 수용 정도에 차이가 있는 것을 발견할 수 있었다. 스마트 피트니스웨어에 대한 기능 수요에 대한 차이점으로는 전문 트레이너의 경우 운동 효과의 과학적 향상에 중점을 두는 반면 일반 소비자는 운동 시 지속성을 고려한 기능을 중요시 하는 것으로 분석되었다. 본 연구 결과를 종합하여 '심박 센싱, 근육 활성도 센싱, 부위별 운동 동작 각도 또는 자세 센싱, 운동량 센싱 등의 기능 탑재', '전문가 라인과 일반 라인별 컨셉 및 컨텐츠 개발', '압박 의류 형태로 디자인', '운동지역에 따른 상품개발의 차별화' 등의 상품기획 및 디자인 방향을 제시하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.1051-1054
• /
• 2002

Environmentally conscious machining and technology have been taking more and more important position in machining process. Since cutting fluid has some impact on environment, many researches are being carried out to minimize the use of cutting fluid. It can be Increased the environmental pollution through not using coolant any more or minimizing it. In this study, the cooling effects of cutting methods using the compressed cold air, dry cutting and cutting fluid will investigate in the blade machining. In order to examine the characteristics of cutting and tool in the environmentally conscious machining, this work investigates experimentally the degree of tool wear, cutting force and characteristics of surface roughness in relation to machining conditions and cooling methods.