• 한국의류산업학회지
• /
• 제3권2호
• /
• pp.105-114
• /
• 2001

The result of this study is on textile expressed in the costume of the Kazakh tribe, Kirgiz tribe, Tajik tribe. Basically the material of costume is fur, cotton flannel, felt, silk, cotton outwear, velvet cloth and beads, silver, earing, bracelet is used frequently. The tribes did embroider on the shoes, made of sheepskin or calfskin and collar, belt, button, pocket with the sketch of national trait. Eventually their cultures of costume seem to be very similar because of the resemblances in circumstance of nature, religion, custom of life but definitely they show conservatism in itself and independent culture. In the basic structure of traditional costume by races, there is no big difference. Then, in men, the trousers and the shirts of tunic type become the basic with the style which is convenient to act. And, to wear vest, or jacket, or chaban, over it makes a little difference. In women also, same structure shows with the form to wear vest or outwear, on the basis of one piece. But, in a small hat, head wear, color contrast, and decoration element etc., strict difference is showing. After all, they show very similar clothing life culture basically in natural environment, religion, and life habit etc., But, the discrimination is made in the detailed side. So, it can be said that they show the conservative nature of nationalities, and have preserved the unique identity of their own culture.

• Tribology and Lubricants
• /
• 제27권6호
• /
• pp.321-325
• /
• 2011

Nanodiamond was dispersed in paraffin liquid oil to investigate the effects of nanodiamond at the marginally lubricated condition. Scuffing test and immediate loading sliding wear test were conducted using the fabricated nanodiamond oil. As a result, dispersion of nanodiamond in oil leads to increase in scuffing life, and nanodiamond contents affects the scuffing life. In case of immediate loading sliding wear test, the result was different according to hardness of specimen. If hardness of specimen was low, abrasion of nanodiamond occurred actively. If hardness of specimen was increased, however, nanodiamond can act as a spacer or rolling between contacting surfaces.

• 대한금속재료학회지
• /
• 제48권7호
• /
• pp.651-659
• /
• 2010

When high-speed interrupted cutting is carried out for die and mold steels with high hardness, CBN tools manifested a significantly longer wear life than carbide, ceramic, or cermet tools in an experiment of face milling characteristics. In addition, it was also found that they secured a stable surface roughness within a range of 1.6 S~6.3 S, an acceptable range for precision machining for polished machining parts. And it makes them acceptable in the precision machining field, except in industries where very high machining accuracy is required. In the high hardness interrupted cutting, it was advantageous to perform a negaland treatment and a honning treatment on the tools' cutting edge to extend tool life and surface roughness. Also, severe crater development was found on the sloped face in CBN tools following high-speed machining. This caused the cutting edge to be weakened and damaged, and ultimately resulted in a shorter tool life. Finally, as a result of EDX mapping inspection, Cr component was detected evenly on the entire crater wear area, which can be included only in STD 11.

• 한국정밀공학회지
• /
• 제20권7호
• /
• pp.26-35
• /
• 2003

This study explains the effects of lubricant and surface treatment on hot forging die life. The mechanical and thermal load, and thermal softening which is happened by the high temperature of die, in hot and warm forging, cause die wear, heat checking and plastic deformation, etc. This study is fur the effects of solid lubricants and surface treatment condition for hot forging die. Because cooling effect and low friction are essential to the long life of dies, optimal surface treatment and lubricant are very important to improve die life for hot forging process. The main factors, which affect die hardness and heat transfer, are surface treatments and lubricants, which are related to thermal diffusion coefficient and heat transfer coefficient, etc. For verifying these effects, experiments are performed for hot ring compression test and heat transfer coefficient in various conditions as like different initial billet temperatures and different loads. The effects of lubricant and surface treatment for hot forging die life are explained by their thermal characteristics. The new developed technique in this study for predicting tool life can give more feasible means to improve the tool life in hot forging process.

• Tribology and Lubricants
• /
• 제22권3호
• /
• pp.131-136
• /
• 2006

Cylinder bore wear may not be a problem in most current automotive engines. However, a small change in cylinder bore diameter can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blow-by and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each pare0s wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of cylinder bore diameter are obtained from three engines before and after engine durability test. The calculated wear data of cylinder bore diameter are turn out to be twice of the lower bound of averaged test values at TDC and the lower bound at BDC.

• 폴리머
• /
• 제29권1호
• /
• pp.48-53
• /
• 2005

타이어 마모는 자동차 드라이버들의 주요 관심 사항 중의 하나일 뿐만 아니라 타이어의 수명과 밀접하게 관련되어 있다. 자동차 타이어의 사용 조건들은 여러 가지 요인들이 함께 작용하기 때문에 타이어 마모에 대해 명확하게 규명하는 것은 쉽지 않다. 따라서, 타이어 마모를 평가하기 위해서는 실제 사용 조건에서의 마모 평가가 필요하다. 타이어의 수명과 밀접한 관련이 있는 마모를 평가하기 위하여 정해진 가혹한 주행 조건을 갖는 dedicated test를 통하여 마모 성능 시험을 실시하였다. 타이어 마모에 영향을 미치는 많은 인자들을 단순화시키기 위하여 정해진 운전자의 가혹도로 시험함으로써 운전자의 운전 습관에 따른 영향을 최소화하였다. 마모와 관련이 있는 노선 가혹도의 영향을 확인하기 위하여 노선 별로 횡가속도를 측정하여 얻어진 driving severity number(DSN)을 이용하여 DSN에 따른 타이어의 마모율과 마모 양상에 대해 비교해 보았다. 이러한 dedicated treadwear test 결과를 제공함으로써 타이어 마모 성능을 만족시키기 위한 설계에 유용한 자료를 제공할 수 있다.

• International Journal of Precision Engineering and Manufacturing
• /
• 제5권4호
• /
• pp.5-13
• /
• 2004

This study explains the effects of lubricant and surface treatment on the life of hot forging dies. The thermal load and thermal softening, that occur when there is contact between the hotter billet and the cooler dies in hot forging, cause wear, thermal cracking and fatigue, and plastic deformation. Because the cooling effect and low friction are essential to the long life of dies, the proper selection of lubricant and surface treatment is very important in hot forging process. The two main factors that decide friction and heat transfer conditions are lubricant and surface treatment, which are directly related to friction factor and surface heat transfer coefficient. Experiments were performed for obtaining the friction factors and the surface heat transfer coefficients in different lubricants and surface treatments. For lubrication, oil-base and water-base graphite lubricants were used, and ion-nitride and carbon-nitride were used as surface treatment conditions. The methods for estimating die service life that are suggested in this study were applied to a finisher die during the hot forging of an automobile part. The new techniques developed in this study for estimating die service life can be used to develop more feasible ways to improve die service life in the hot forging process.

• Tribology and Lubricants
• /
• 제25권4호
• /
• pp.261-264
• /
• 2009

Environmental factors affect parts of the automobile. When dust particles are embedded, specially, friction and wear of the rubber-seal in automobile chassis system are increased. Increase in friction and wear leads to weakness of component and reduction of mechanical life. In this study, the wear characteristics of rubber-seal for inflow of dust particles are investigated. Silica($SiO_2$) and alumina($Al_2O_3$) particles are used as a dust particle because these particles are main elements of dust particles. The sliding wear tester are used for investigate the wear characteristics of rubber-seal. If the single dust particle($SiO_2$) is embedded in the rubber-seal component, the influence of dust particle size is more than that of inflow rate on the wear characteristics of rubber-seal. If the mixed dust particles are embedded in the rubber-seal component, the wear rate is increased as the rate of alumina that has a bigger hardness is increased. If the mixed dust particles that have different hardness are embedded in the rubber-seal component, the influence of particle size is more than that of particle hardness.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2002년도 제35회 춘계학술대회
• /
• pp.53-62
• /
• 2002

Condition monitoring plays a vital role since it sustains reliable operation of industrial plants and machinery in the pursuit of economic whole life operation. In order to achieve this goal, it is needed to monitor various parameters of mechanical system such as vibration, wear, temperature and etc., and finally to diagnosis the root causes of any possible abnormal machine condition. In this work, a machine failure caused by mechanical looseness was experimentally simulated and on-line measurement of the vibration, wear and temperature were simultaneously measured. For the quantitative analyses of machine wear, several statistical parameters of the wear particle size distribution were obtained through the center moment method of the Weibull distribution function, and they were compared to vibrational characteristics. Results showed that the wear and vibrational characteristics did not reveal a strong correlation each other in a loosely supported proceeding bearing.

• Tribology and Lubricants
• /
• 제19권6호
• /
• pp.321-328
• /
• 2003

In the present study, the residual stresses can have a significant on the life of structural engineering components. Residual stresses are created by the surface treatment such as shot peening or deep rolling. The objective of this experimental investigation is to study the influence of friction and wear characteristics due to residual stress under dry sliding condition. Friction and wear data were obtained with a specially designed tribometer. Test specimens were made of SUP9 (leaf spring material) after they were created residual stress by shot peening treatment. Residual stress profiles were measured at surface by means of the X­ray diffraction. Sliding tests were carried out different contact pressure and same sliding velocity 0.035 m/s (50 rpm). Leaf spring assembly test used to strain gauge sticked on leaf spring specimen in order to measure interleaf friction of leaf spring. Therefore, we were obtained hysteresis curve. As the residual stresses of surfaces increased, coefficient of friction and wear volume are decreased, but the residual stresses of surfaces are high, and consequently wear volume do not decreased. Coefficient of friction obtained from leaf spring assembly test is lower than that obtained from sliding test. From the results, structural engineering components reduce coefficient of friction and resistant wear in order to have residual stresses themselves.