• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.119-124
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• 1999

Quantitative evaluation of the tribological conditions at the tool-workpiece interface in metal forming is usually accomplished by the ring-compressinon. test This paper describes an experimental investigation into shear friction factor under cold and hot forming conditions according to materials and lubricants using the ring compression test. Six different materials and five different lubricants were applied in the experiments. calibration curves with the friction coefficient were obtained using FEM analysis and verified by the verified by the experimental results. The influence of materials and lubricants level on friction are discussed. In the ring compression test the shear friction factor has a different from steels and aluminum water base graphite lubricants on cold working conditions and hot working conditions.

• 한국정밀공학회지
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• 제16권8호
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• pp.59-70
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• 1999

This paper deals with automated computer-aided process planning by which designers can determine operation sequences even if they have little experience in the design of press working products. The computer-aided process planning in hot forging, deep drawing and blanking requires many kinds of technical and empirical skills based on investigation and collection of the knowledge of their processes. An approach to the CAPP system is based on the knowledge-based rules and the process knowledge base consisting of process planning rules is built. The methodology adopted to develop the system is elaborated in this paper. This system has been written in AutoLISP on the AutoCAD with a personal computer and provides powerful capabilities for process planning of hot forging, cold forging, deep drawing and blanking products.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1494-1496
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• 1997

The MRI Magnet is a most practical application of NbTi superconductor. In this paper, we present the main research results on superconducting wires for MRI magnet which we have developed. Cu/NbTi superconducting wires were fabricated by repeat of cold working and heat-treating process after that billets were extruded. We investigated the relation of superconductivities of wires and heat treatment condition. The correlation between cross section shape of wires and work inhomogeneity of NbTi rods was investigated by microscopic observation. The more repeatation number of cold working and heat-treating process, the higher critical current is achieved.

• International Journal of Reliability and Applications
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• 제2권4호
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• pp.253-262
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• 2001

A k-out-of-n standby system is considered where all of its components are s-independent and classified either working or cold standby connected with imperfect switches. The probability density function of the life length for this system is established in closed form, when the underlying components have constant failure rates. Also the reliability function of the system is derived. Finally, the reliability functions for one, two and three out of four systems are deduced for perfect or imperfect switches and identical or non-identical constant failure rates for working and standby components.

• 대한기계학회논문집B
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• 제25권1호
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• pp.108-116
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• 2001

The vortex tube is a simple device which separates fluid stream into a cold stream and a hot stream without any chemical reaction. The process of energy separation in the vortex tube has caused a great deal of interest. Although many studies on energy separation in the vortex tube using air as the working fluid have been made so far, few experimental studies treated energy separation for incompressible fluid. So, an experimental study for the energy separation in the vortex tube using the water which is essentially an incompressible fluid is presented. When working fluid is the water, the best geometric values of nozzle area ratio and number of nozzle holes are 0.155, 6 respectively. These geometric values are showed by the similar values which are presented by compressible fluid as working fluid. But hot side mass fraction of which maximum temperature drop is happened are different from compressible fluid.

• 가정과삶의질연구
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• 제16권4호
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• pp.1-16
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• 1998

this study examined the correlates of adult attachment focused on internal working models of 201 housewives. Findings indicated that 68.3% of subjects were classified as secure whereas 27.5% as avoidant and 4.2% as anxious. Greater security was associated with slightly less avoidance while greater anxiousness was associated with slightly greater avoidance. That is subjects who possessed more security tended to be less avoidant while subjects who possessed more anxiousness tended to be more avoidant. The primary characteristics classifying subjects into those three attachment styles were feelings about closeness dependence and anxiousness in relationships with others. Adult attachment was related in theoretically expected ways to one's history of attachment and parenting. Secure subjects were more likely to report warm/responsive parental caregiving style than insecure styles. Insecure subjects in comparison with secure subjects perceived their mothers as cold inconsistent and ot very responsive. Anxious subjects dscribed their fathers as cold and rejecting. The secure attachment style in comparsion with insecure styles was associated with positive mental models of self and social world indicating greater self-esteem positive beliefs about self and others positive relationships with their children greater marital satisfaction and greater secure attachment to their husbands. These results suggest that internal working model offers a useful perspective on adult attachment.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1994년도 춘계 학술발표 강연 및 논문 개요집
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• pp.63-63
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• 1994

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 춘계학술강연 및 발표대회
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• pp.14-15
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• 2003

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.203-206
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• 2008

Transformation of austenite to martensite during cold rolling has been widely used to strengthen metastable austenitic stainless steel grades. Aging treatment of cold worked metastable austenitic stainless steels, including ${\alpha}'$-martensite phase, results in the further increase of strength, when aging is performed in $200^{\circ}C$ to $450^{\circ}C$ temperature range. The purpose of the present study was to evaluate the effect of time and temperature on the stress-strain behavior of cold worked austenitic stainless steels. The amount of ${\alpha}'$-martensite during cold working and aging was examined by ferrite scope and X-ray diffraction (XRD). During aging at $450^{\circ}C$ for 1hr, tensile strength dramatically increased by 150MPa. Deformed metastable austenitic steels containing the "body-centered" ${\alpha}'$-martensite are strengthened by the diffusion of interstitial solute atoms during aging at low temperature.

• 한국수소및신에너지학회논문집
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• 제31권4호
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• pp.363-371
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• 2020

Recently, the technologies to utilize the cold energy of liquefied natural gas (LNG) have attracted significant attention. In this paper, thermodynamic performance analysis of combined cycles consisting of ammonia Rankine cycle (AWR) and organic Rankine cycle (ORC) with LNG Rankine cycle to recover low-grade heat source and the cold energy of LNG. The mathematical models are developed and the effects of the important system parameters such as turbine inlet pressure, ammonia mass fraction, working fluid on the system performance are systematically investigated. The results show that the thermal efficiency of AWR-LNG cycle is higher but the total power production of ORC-LNG cycle is higher.