• 한국재료학회지
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• 제28권7호
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• pp.381-390
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• 2018

Shape memory alloys(SMAs) have revolutionized the material engineering sciences as they exhibit exclusive features i.e. shape memory effect(SME) and super-elasticity. SMAs are those alloys that when deform return to their predeformed shape upon heating, they also restore their original shape by removing the load. Research on properties of newly advent of several types of ferrous based shape memory alloys(Fe-SMAs), shows that they have immense potential to be the counterpart of Nitinol(NiTi-SMA). These Fe-SMAs have been used and found to be effective because of their low cost, high cold workability, good weldability & excellent characteristics comparing with Nitinol(high processing cost and low cold workability) SMAs. Some of the Fe-SMAs show super-elasticity. Fe-SMAs, especially Fe-Mn-Si alloys have an immense potential for civil engineering structures because of its unique properties e.g. two-way shape memory effect, super elasticity and shape memory effect as well as due to its low cost, high elastic stiffness and wide transformation hysteresis comparative to Nitinol. Further research is being conducted on SMAs to improve and impinge better attributes by improving the material compositions, quantifying the SMA phase transition temperature etc. In this research pre-existing Fe-SMAs are categorised and collected in a tabulated form. An analysis is performed that which category is mostly available. Last 50 years data of Fe-SMA publications and US Patents is collected to show its importance in terms of increasing research on such type of alloys to invent different compositions and applications. This data is analysed as per different year groups during last 50 years and it was analysed as per whether the keywords exist in title of an article or anywhere in the article. It was found that different keywords related to Fe-SMAs/categories of Fe-SMAs, almost don't exist in the title of articles. However, these keywords related to Fe-SMAs/categories of Fe-SMAs, exist inside the article but still there are not too many publications related to Fe-SMAs/categories of Fe-SMAs.

• 한국IT서비스학회지
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• 제10권3호
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• pp.213-236
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• 2011

Mobile devices are widely accepted as a convenient machine which provides computing capability as well we cell phone capability. Because of limited resources on mobile devices, complex applications could not be deployed on the devices. Service-based mobile applications (SMAs) can provide a solution to overcome the limitation by subscribing cloud services. Since SMAs have complex structures than standalone applications, it is challenging to develop high quality SMAs, to manage both services and mobile applications, and to implement automated billing for subscribed services. Therefore, there is a great demand for a platform for super mobile computing, which supports all key activities in managing life cycle of SMAs. In this paper, we present technical aspects of a platform which is under development; Super Mobile Autonomous Reliable plaTform (SMART). We believe that it provides a number of practical features which are essential in supporting life-cycle of SMAs; development, deployment, management, and operation.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.10-13
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• 2003

The dynamic analysis of composite plate with embedded shape memory alloys (SMAs) is studied using the finite element method. Active frequency tuning of a composite plate under electrical heating of SMAs is analyzed. The actuation of SMAs is modeled by Brinson's one-dimensional constitutive equation. The influences of the boundary conditions, the ply orientations and the pre-strains of SMA wires on the thermo-dynamic response of composite plate are discussed. It is found that the effect of SMAs on the dynamic response of composite plate is significant.

• 보건행정학회지
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• 제30권3호
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• pp.277-285
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• 2020

Chronic diseases as well as a growing population of older adults are currently the leading cause of ill health and economic burden worldwide. Managing those diseases in one-on-one medical consultations poses substantial challenges due to limited time and resources in the current health care system. Various approaches have been taken to manage these conditions, most with limited success. Shared medical appointments (SMAs) are an innovative care delivery option to make the testing of alternative care modalities a prime concern. SMAs are individual medical consultations carried out in a group of patients with similar diseases by providing education, medication management, and disease monitoring. SMAs, since their initial conceptualization in 1998, have gained much popularity and adopted as one of the standard processes in many countries. Accumulated evidence-based studies show outcomes for increasing access to care, behavioral change facilitated through self-management education, maintained/better outcomes, physician productivity, and enhanced resource management. This review summarizes current evidence regarding the existing status of SMAs abroad. An extensive literature search was conducted on major electronic databases including PubMed and Google Scholar. This study suggests to explore and exploit the SMAs which have unique potential as a healthcare delivery innovation in Korea.

• 도시과학
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• 제7권1호
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• pp.5-9
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• 2018

The nickel-titanium shape memory alloy (SMA), referred to as Nitinol, exhibits a superelastic effect that can be restored to its original shape even if a significant amount of deformation is applied at room temperature, without any additional heat treatment after removal of the load. Owing to these unique material characteristics, it has widely used as displacement control devices for seismic retrofitting in civil engineering fields as well as medical, electrical, electronic and mechanical fields. Contrary to ordinarty carbon steel, superelastic SMAs are very resistant to fatigue, and have force-displacement properties depending on loading speed. The change for the mechanical properties of superelastic SMAs are experimentally inviestigated in this study when loading cycle numbers and loading speeds are different. In addition, the standardized force-displacement properties of such superelastic SMAs are proposed with an aim to efficiently design the seismic retrofitting devices made of these materials.

• Smart Structures and Systems
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• 제22권5호
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• pp.495-508
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• 2018

Shape memory alloys (SMAs) exhibit superelasticity given the ambient temperature is above the austenite finish temperature threshold, the magnitude of which significantly depends on the metal ingredients though. For the monocrystalline CuAlBe SMAs, their superelasticity was found being maintained even when the ambient temperature is down to $-40^{\circ}C$. Thus this makes such SMAs particularly favorable for outdoor seismic applications, such as the framed structures located in cold regions with substantial temperature oscillation. Due to the thermo-mechanical coupling mechanism, the hysteretic properties of SMAs vary with temperature change, primarily including altered material strength and different damping. Thus, this study adopted the monocrystalline CuAlBe SMAs as the kernel component of the SMA braces. To quantify the seismic response characteristics at various temperatures, a wide temperature range from -40 to $40^{\circ}C$ are considered. The middle temperature, $0^{\circ}C$, is artificially selected to be the reference temperature in the performance comparisons, as well the corresponding material properties are used in the seismic design procedure. Both single-degree-of-freedom systems and a six-story braced frame were numerically analyzed by subjecting them to a suite of earthquake ground motions corresponding to the design basis hazard level. To the frame structures, the analytical results show that temperature variation generates minor influence on deformation and energy demands, whereas low temperatures help to reduce acceleration demands. Further, attributed to the excellent superelasticity of the monocrystalline CuAlBe SMAs, the frames successfully maintain recentering capability without leaving residual deformation upon considered earthquakes, even when the temperature is down to $-40^{\circ}C$.

• 한국항공우주학회지
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• 제39권1호
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• pp.9-15
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• 2011

변형률-속도에 따른 형상기억합금의 초탄성 거동 특성 변화를 실험적 그리고 수치적으로 살펴보았다. 변형률-속도를 고려한 형상기억합금의 수학 모델을 유도하였고, 형상기억합금의 실험결과를 바탕으로 변형률 속도에 따른 형상기억합금의 열-기계적 특성변화를 관찰하였다. 변형률-속도의 변화에 따라 형상기억합금 시편의 급격한 온도변화가 일어남을 확인하였고 이런 현상이 초탄성 거동 특성 변화에 큰 영향을 미침을 예측 할 수 있었다.

• 소성∙가공
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• 제20권5호
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• pp.350-356
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• 2011

Shape memory alloys(SMAs) exhibit pseudoelastic behavior, characterized by the recovery of an original shape even after severe deformation, during loading and unloading within appropriate temperature regimes. The distinctive mechanical behavior is associated with stress-induced transformation of austenite to martensite during loading and reverse transformation to austenite upon unloading. To develop a material model for SMAs, it is imperative to consider the difference in moduli of active phases. For example, the Young’s modulus of the martensite is one-third to one half of that of the austenite. The model proposed herein is a modification of the one proposed recently by Ho[17]. The prediction of the behavior of SMAs during unloading before the onset of reverse transformation was improved by introducing a new internal state variable incorporating the variation of the elastic modulus.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.478-485
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• 2002

The shape memory alloys (SMAs) are often used in smart materials and structures as the active components. Their ability to provide a high recovery force and a large displacement has been used in many applications. In this paper the radial displacement of an externally pressurized elliptic composite cylinder where SMA liner or strips actuators are bonded on its inner or outer surface is investigated numerically. The elliptic composite cylinders consisting of an inlet duct system with SMAs are designed and analyzed to determine the feasibility of such a system for the removal of stiffeners from an externally pressurized duct of an aircraft inlet. The deformations caused by prestrained SMAs placed on either surface of an elliptic composite cylinder are studied when activated. The externally pressurized elliptic composite cylinders with the SMA actuators were analyzed using the 3-D finite element method incorporated with 3-D SMA behaviors. The results show that the role of stiffeners may be switched by the activated light SMA actuators.

• 대한기계학회논문집A
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• 제34권8호
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• pp.1083-1089
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• 2010

형상기억합금은 지능형 재료와 구조물에 널리 쓰인다. 큰 힘과 변위를 발생시키는 것이 특징이며 작동기, 소음 및 진동감쇠, 동역학적 튜닝, 형상의 변형 제어 등의 다양한 분야에 응용될 수 있다. 본 논문에 서는 형상기억합금튜브와 초탄성 스프링으로 구성된 형상기억합금 비틀림 작동기를 제안하였고 각각의 거동 특성을 알아보았다. 열전달 해석을 통해 저항열과 히터의 열을 동시에 형상기억합금튜브에 가하면 작동기의 성능을 더 향상시킬 수 있음을 확인하였다. 접촉 해석으로는 실제 작동기의 거동을 시뮬레이션하였고 정상적으로 작동함을 알 수 있었다. 3 차원 형상기억합금의 거동을 표현하기 위해 비선형 구성방정식을 유한요소 법으로 풀고 ABAQUS 의 U-MAT 기능을 이용하여 비선형 해석을 수행하였다.