• 소성∙가공
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• 제13권2호
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• pp.168-173
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• 2004

Microforming can be a good application for bulk metallic glasses. It is important to simulate the deformation behaviour of the bulk metallic glasses in a supercooled liquid region for manufacturing micromachine parts. For these purposes, a correct constitutive model which can reproduce viscosity results is essential for good predicting capability. In this paper, we studied deformation behaviour of the bulk metallic glasses using the finite element method in conjunction with the fictive stress constitutive model which can describe non-Newtonian as well as Newtonian behaviour. A combination of kinetic equation which describes the mechanical response of the bulk metallic glasses at a given temperature and evolution equations fur internal variables provide the constitutive equation of the fictive stress model. The internal variables are associated with fictive stress and relation time. The model has a modular structure and can be adjusted to describe a particular type of microforming process. Implementation of the model into the MARC software has shown its versatility and good predictive capability.

• 자원리싸이클링
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• 제23권5호
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• pp.62-67
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• 2014

금속캔은 리싸이클링이 용이한 포장용기로서 금속 폐캔을 효율적으로 리싸이클링하는 것은 자원재활용 측면에서 매우 중요한 일이다. 금속캔은 EPR 해당 품목으로서 재질에 따라 스틸캔과 알루미늄캔으로 분류되는데, 국내의 경우에는 스틸캔이 80% 가량을 차지하고 있다. 본 고에서는 2008년부터 최근 5년간 금속 폐캔 발생량과 재활용 현황 및 처리방법을 알루미늄캔과 스틸캔별로 조사하였다. 2012년 금속캔의 재활용을 중량비로 살펴보면 스틸캔이 80.8%, 알루미늄캔은 81.8%였으며 금속캔 전체로는 81.1%의 재활용율을 기록하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.77-77
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• 2015

Metallic glass alloys having dense packing structure have short range ordered structure with long range homogeneity. Therefore, they can provide complete corrosion protection and unique electrical properties. Recently, metallic glass thin films have received much attention to extend its application fields combining with PVC coating technologies. The metallic glass thin films can change the surface properties of the conventional bulk materials which need anticorrosion properties. However, multi-component alloying targets are required to fabricate the metallic glass thin films because metallic glass alloys contain more than three elements. Recently, many researchers have been reported the properties of the metallic glass thin films synthesized with multi-cathode systems or amorphous target. But, it is difficult to fabricate the large sized sputtering targets for mass production equipment with high toughness and thermal stability. In this study, newly developed sputtering target with glass forming ability and the properties of the metallic glass thin films will be introduced with respect to the various application fields such as bipolar plate in PEM fuel cell and decorative coatings for electric device and construction fields.

• Corrosion Science and Technology
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• 제7권1호
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• pp.6-12
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• 2008

Non-metallic composite overwrap repair methods utilize resin based fiber-reinforced composite materials, which have higher specific strength to weight ratio and stiffness, superior corrosion and fatigue resistance, and substantially reduced weight when compared to carbon steel. Non-metallic repair methods/systems can allow desired functional properties to be achieved at a respectable economic advantage. For example, non-metallic composite repair systems have at least a 50 year design stress of 20 ksi and approximately 25% of the short term tensile strength of fiberglass. For these systems, the contribution of the repaired steel to the load carrying capability need not be considered, as the strength of the repair itself is sufficient to carry the internal pressure. Worldwide experience in the Oil & Gas industry confirms the integrity, durability, inherent permanency, and cost-effectiveness of non-metallic composite repair or rehabilitation systems. A case study of a recent application of a composite repair system in Saudi Aramco resulted in savings of 37% for offshore subsea line and 75% for onshore above grade pipeline job. Maintaining a pipeline can be costly but it is very small in comparison to the cost of a failure. Pipeline proponents must balance maintenance costs with pipeline integrity. The purpose is not just to save money but also to attain a level of safety that is acceptable. This technology involves the use of an epoxy polymer resin based, fiber-reinforced composite sleeve system for rehabilitation and /or repair pipelines.

• Structural Engineering and Mechanics
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• 제56권4호
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• pp.569-588
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• 2015

A comprehensive methodology is proposed for design of metallic dampers in seismic retrofit of earthquake-damaged frame structures. It is assumed that the metallic dampers remain elastic and only provide stiffness during frequent earthquake (i.e., earthquake with a 63% probability of exceedance in 50-year service period), while in precautionary earthquake (i.e., earthquake with a 10% probability of exceedance in 50-year service period), the metallic dampers yield before the main frame and dissipate most of the seismic energy to either prevent or minimize structural damages. Therefore by converting multi-story frame to an equivalent single-degree-of-freedom system, the added stiffness provided by metallic dampers is designed to control elastic story drifts within code-based demand under frequent earthquake, and the added damping with the combination of added stiffness influences is obtained to control structural stress within performance-based target under precautionary earthquake. With the equivalent added damping ratio, the expected damping forces provided by metallic dampers can be calculated to carry out the configuration and design of metallic dampers along with supporting braces. Based on a detailed example for retrofit of an earthquake-damaged reinforced concrete frame by using metallic dampers, the proposed design procedure is demonstrated to be simple and practical, which can not only meet current China's design codes but also be used in retrofit design of earthquake-damaged frame with metallic damper for reaching desirable performance objective.

• 대한화학회지
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• 제15권6호
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• pp.330-347
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• 1971

Catalytic effects of metallic salts on the combustion of diesel fuel oil have been studied. In the case of organometallic salt, the active species are the metallic oxides resulted from combustion of the salts. The oxides act only on the residual solid carbon produced from the fuel oil combustion. The catalytic activity can be explained with the semiconductor theory just as in the case of the gas phase reaction. The chemical rate constant of the combustion of carbon, the soot from diesel fuel oil, is found to be $k_c=1.1{\times}10^4\;exp$ (-16,600/T) below $800^{\circ}K$. By addition of metallic oxides, the rate constant increases remarkably. This work has substantiated the belief that the effect of the metallic salts on the fuel oil combustion can conveniently be studied by checking directly the effect of the corresponding metallic oxide on the soot carbon.

• 한국대기환경학회지
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• 제19권1호
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• pp.45-56
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• 2003

In this study the distribution patterns of the metallic components were analyzed both before and after the Asian Dust (AD) events at 2001 by comparing the chemical composition of metallic components in terms of various statistical methods. According to the AD/NAD concentration ratio of metallic components, the main components of crustal soils were exhibiting the values above 1.0; but opposite results were seen dominantly for hazardous metallic components. Examination of fine-to-coarse (F/C) ratios of metallic components showed higher values for major anthropogenic components including Pb (5.83). Ni (2.61), etc. Comparison of our measurement data with those obtained within and across the Korean peninsula indicated that the metallic distribution patterns of the study area can be distinguished from previous studies. The results of our analysis, when investigated in relation with air mass movement patterns. indicated evidence of the direct influence of AD events and anthropogenic processes.

• JSTS:Journal of Semiconductor Technology and Science
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• 제7권2호
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• pp.82-87
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• 2007

The electrical properties of metallic junction diodes and metallic source/drain (S/D) Schottky barrier metal-oxide-semiconductor field-effect transistor (SB-MOSFET) were simulated. By using the abrupt metallic junction at the S/D region, the short-channel effects in nano-scaled MOSFET devices can be effectively suppressed. Particularly, the effects of trap states at the metal-silicide/silicon interface of S/D junction were simulated by taking into account the tail distributions and the Gaussian distributions at the silicon band edge and at the silicon midgap, respectively. As a result of device simulation, the reduction of interfacial trap states with Gaussian distribution is more important than that of interfacial trap states with tail distribution for improving the metallic junction diodes and SB-MOSFET. It is that a forming gas annealing after silicide formation significantly improved the electrical properties of metallic junction devices.

• 한국기계가공학회지
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• 제12권6호
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• pp.142-151
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• 2013

This study develops an automation system for metallic mold design that is applicable in forging non-axial symmetric parts. The metallic mold design program is used to design the metallic mold using two-dimensional axial symmetric metallic molds and to predict the stress concentration using finite element analyses. Then, the program redesigns the metallic mold using variables such as the optimal split diameter, maximum allowable inner pressure, fit tolerance, and stress distribution, which are calculated using the metallic mold design program. When the involute spur gear is forged, stress concentration occurs on the tooth root bounded at the symmetric surface. The SCM4 material is suitable for metallic molds because the stress is less than the yield strength of the insert and it acts on the tooth root regardless of the inner pressure. The metallic mold for forging non-axial symmetric parts can be designed through adjusting the magnitude of the contact pressure. The program developed in this study can be applied to metallic mold designs in involute spur gears of forging, which is an ordinary non-axial symmetric part.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2007년도 학술대회 1부
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• pp.1037-1044
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• 2007

Metallic paint is one of the most widely used coating in automotive, cosmetic and other applications because of its well-known ability to give a product realistic look which creates widespread consumer appeal. But, this coating has complicated subsurface structure which includes pigments, flakes, and transparent clearcoat. Though various analytic reflection models are available to simulate appearance of various surfaces, it is difficult to select an appropriate reflection model with faithful parameters for simulating this coating due to the complex subsurface structure of metallic paints. This paper presents a framework for accurate modeling of metallic coating by determining an appropriate reflection model among various existing BRDF (Bidirectional Reflectance Distribution Function) models. The selection of the appropriate model is achieved by measuring BRDF of various metallic paint samples using a BRDF measuring device i.e. gonioreflectometer and fitting an existing model to the measured data. Then, this model is effectively realized by rendering metallic painted surfaces. We believe that this framework can serve as a guide for those who wants to render metallic painted surfaces accurately with analytic BRDF model without expending time on extracting BRDF data using gonioreflectometer from real metallic paint sample.