• Journal of Chest Surgery
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• 제19권4호
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• pp.688-694
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• 1986

Takayasu`s disease is an arteritis of unknown etiology involving larger elastic arteries such as aorta and its branches, pulmonary arteries and rarely coronary arteries. Especially, aortic root involvement with the valvular leaflets has been reported in several cases of Takayasu`s arteritis. Recently we have experienced one case of Takayasu`s arteritis involving left subclavian artery, descending aorta, left renal artery and multiple valvular leaflets. The patient was 33 year-old female and admitted with complaints of cough, dyspnea and general weakness. Aortogram revealed extensive type of arteritis showing dilatation of ascending aorta, segmental narrowing of thoracic aorta and Riolan`s anastomosis. Double valve replacement [mitral and aortic valve] and tricuspid valve annuloplasty were performed. The patient made an excellent postoperative recovery and has shown striking improvement in cardiac status, NYHA functional class II eight months after operation.

• 한국염색가공학회지
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• 제11권4호
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• pp.8-15
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• 1999

Electroconductive fiber was obtained by acryl fiber treated with $CuSO_4$. The Properties and structure of fiber and fabric such as mechanical property, electrical conductivity, fine structure, electrification were investigated. The experimental results are as follows 1) The electrical conductivity of the conducting fiber was greatly increased but fine structure and physical properties were similar to acryl fiber 2) Fabric made by mix spinning with conducting fiber was shown great electrification effect. 3) In the mix spinning with conducting fiber, it was necessary to use different. finishing such as milled finish because stiffness of fabric made by mix spinning with conducting fiber was increased and elastic recovery was decreased. 4) The antimicrobial activity of electroconductive fiber blended wool was effective by Cu component for shake flask test.

• 대한가정학회지
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• 제19권2호
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• pp.143-149
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• 1981

Consumer consider the purpose for which they plan to use clothes when they purchase it, and the socks in textile products is evaluated in the same way. serviceability is judged by the extent to which the socks will be useful for its intended purpose. It should retain its original shape and size, good air permeability, good absorbency, good abrasion resistance, high fastness etc. Owing to importance of serviceability in socks, in this paper, these end-use requirement characteristics were tested. The results obtained were as follows: 1. Blend ratios were different between the indicated fiber contents on labels and the testing ones. 2. Air permeability was higher in the samples which contain less stitch density, and hydroscopicity was higher in those which contain natural fibers such as cotton and wool. 3. Shrinkage depended on the blend ratios of cotton and wool, and elastic recovery was better in the course direction than in the wale direction. 4. Pilling was conspicuous in the synthetic fibers such as polyester and nylon, and fastness of laundering and perspiration was higher in the fading grade than in the staining grade.

• 한국안전학회지
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• 제29권4호
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• pp.28-33
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• 2014

Recently, the actuator worked by the driving recovery-force of the thermo elastic martensitic transformation of shape memory alloys(SMA) has been studied. This paper presents a study on the fatigue life of shape memory alloy (SMA) actuators undergoing thermally induced martensitic phase transformation under various stress levels. shape memory recoverable stress and strain of Ti-44.5at.%Ni-8at.%Cu alloys were by means of constant temperature tensile tests. Differential scanning calorimetry (DSC) was employed in order to investigate the transformation characteristics of the alloy before the tests. the results were summarized as follows. The martensite inducing stress incerased with the increasing of the Cu-contents. The fatigue life decreased with the increasing of the test load and the Cu-content. The data acquired will be very useful during the design process of an SMA NiTiCu element as a functional part of an actuator.

• Design & Manufacturing
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• 제15권1호
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• pp.21-25
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• 2021

When the product is removed from the mold after molding during the sheet metal molding process, elastic recovery causes a springback phenomenon. Much research has been done to minimize this phenomenon. In this study, V-bending experiments were conducted using galvanized steel sheets, stainless steel, and aluminum sheet materials, using a total of nine types of thin sheet materials of 1.0t, 1.5t, and 2.0t, respectively. Molding analysis and experimental data were compared and analyzed. In the case of galvanized steel sheets, it was considered that the springback phenomenon occurs more frequently in molding analysis than in experiments. It was considered that the springback phenomenon occurs greatly in the experiment, not the interpretation of the molding of the stainless steel plate and the aluminum plate. It was considered that the springback occurrence tendency of the molding analysis and the experiment was the same, and the springback occurrence error rate of the molding analysis and the experimental result was about 4.0%.

• 한국가시화정보학회지
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• 제21권1호
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• pp.40-46
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• 2023

For application to drag-based propulsion system, the dynamics of a segmented structure with multiple hinges undergoing oscillatory motion are investigated. The side flaps are connected to a centre rod with elastic plates acting as hinges. The hinges bend to only one direction so that the structure behave asymmetrically between the power stroke and the recovery stroke. An analytical model is proposed, which estimates the asymmetric deformation of the segmented structure coupled with hinges. Using the proposed model, the effects of key geometric and kinematic parameters on the dynamics of the structure are analyzed.

• 자원리싸이클링
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• 제31권1호
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• pp.46-55
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• 2022

최근 희유금속 자원 회수에서 초경합금 스크랩 재활용의 중요성이 증가하고 있다. 그러나 IV, V족 전이금속 질화물로 코팅된 초경합금 스크랩에서 고순도 분말 회수에서 어려움을 겪고 있다. 제1원리 계산을 사용하여 IV 및 V족 전이금속 질화물(TiN, VN, ZrN, NbN, HfN 및 TaN)의 구조, 탄성 및 기계적 특성을 조사하였다. IV족 전이금속 질화물은 V족 전이금속 질화물보다 높은 공유결합 특성을 보였다. 따라서 IV족 전이금속 질화물은 V족 전이금속 질화물보다 취성 거동을 보였다. 대조적으로 V족 전이금속 질화물은 최외각전자 농도에 영향받는 금속결합의 특성 때문에 IV족 전이금속 질화물보다 전단응력에 대한 약한 저항성과 연성 거동을 보였다. Crystal orbital Hamilton population 분석 결과는 모든 전이금속 질화물의 전단 저항 경향성이 일치함을 보여주었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1507-1510
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• 2005

This study was carried out as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-\mu{m}-deep$ indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.49 GPa and 100 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46-0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined area during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

• Smart Structures and Systems
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• 제17권5호
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• pp.819-835
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• 2016

In this paper, the activities carried out within the EU funded Clean Sky Joint Technology Initiative (JTI GRA) Project and aimed at developing a morphing flap, are illustrated. The reference device is a regional aircraft single slotted flap, enhanced with deforming capabilities to obtain improved hyper-lift performance. The design started with the identification of the internal architecture, intended to allow camber variations. A concentrated-hinge architecture was selected, for its ability to fit different curvatures and for the possibility of easily realizing an "armadillo-like" configuration, then avoiding the use of a complicate deformable skin. The flap layout is made of segmented ribs, elastically hinged each other and span-wise connected by conventional spars. Relative rotations of the rib elements are forced by SMA structural actuators, i.e., cooperating in the external loads absorption. Super-elastic SMA are used to make up recovery elastic elements, necessary to regain the original shape after activation. These further elements in turn contribute to the overall flap rigidity. After assessing the hinge number and the size of the SMA active and passive elements, the advanced design phase was dealt with. It was aimed at solving manufacturing issues and producing the executive drawings. The realized demonstrator was finally tested in lab conditions to prove its functionality in terms of whether target shape actuation or attained shape preservation under loads. On the basis of the numerical results and the experimental outcomes, precious hints were obtained for further developments of the concept.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2292-2299
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• 2010

온열안마기의 내부천으로 사용되고 있는 직물의 내구성을 향상시키고자 기존 PET/면 혼방직물의 마모현상을 분석하고, 그 문제점을 보완할 수 있는 난연성 PET 직물을 설계/제조한 후 물리적 성능 및 내구성을 평가하였다. 기존 직물의 경우 구동부분의 반복적인 마찰에 의한 마모뿐만 아니라, 구동시 내부천의 이동에 의해 발생하는 접힘 현상이 회복되지 못하기 때문에 직물의 파손이 가속화되는 것으로 나타났다. 따라서 섬유재질의 변경, 신축사, 강연사, 조직의 변경 등을 적용하여 물리적 성능 및 내마모성을 크게 개선한 내부천을 제조하였다. 특히 신축사를 사용 한 직물의 내구성은 크게 향상되어 기존 직물 대비 2배 이상의 사용시간을 증가시킬 수 있었으며, 강연사를 사용한 직물은 약 1.5배 정도 내마모시간이 증가하는 결과를 얻었다.