• 동의생리병리학회지
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• 제21권3호
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• pp.709-713
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• 2007

Basement membranes (BMs) are extracellular matrices associated with epithelia, endothelia, muscle, fat and peripheral nerve. They are involved in cell survival, migration, differentiation. BMs functions also include tissue formation and provide mechanical stability as a selective barriers. Laminins are heterotrimeric glycoproteins found in BMs and have a crucial role in cell adhesion and signalling. Madin-Darby canine kidney (MDCK) cells are the best established mammalian model for studying epithelial cell biology The cells form an epithelial monolayer, with tight junctions separating an apical surface from a basolateral membrane facing the filter support and neighboring cells. In this study, using MDCK cells, the synthesis of the BM protein such as laminin with or without methanol extract of Chrysanthemum morifolium (CM) stimulation was analyzed by immunoblotting and CM showed significant increased cell density and enhanced synthesis of laminin.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.87-93
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• 2021

현대 무기체계는 전자장비 탑재의 비중이 늘어나고 있으며, 그에 따른 소프트웨어 탑재비중도 늘어나고 있다. 소프트웨어 비중이 높아감에 따라 그 품질관리와 개발방법에 대한 관심도 높아졌다. 물리적으로 가시화 된 기계체계와 달리 논리적으로 비가시화 된 소프트웨어는 결함에 노출될 경우 복구의 어려움, 재사용의 어려움, 자원의 낭비와 같은 위험에 놓여 질 수 있다. 미국의 경우 국방 소프트웨어의 개발과 품질관리를 위한 별도의 프로세스를 연구하고 적용하는 노력을 통해 CMM(Capability Maturity Model)을 만드는 성과도 거두었다. 우리나라 또한 국제표준을 바탕으로 국방 소프트웨어 개발 및 품질관리에 대한 기준을 만들어 활용하고 있다. 그러나 소프트웨어의 발전 속도에 맞추어 기준을 변경해야 함에도 아직 기초수준에 머무르고 있다는 지적이 있다. 소프트웨어 발전 속도에 비해 기준이 낮다면, 자원 재사용 비용 및 복구비용이 기하급수적으로 늘어난다. 본 논문에서는 CMM의 소프트웨어 테스트 파생형인 TMMi(Test Maturity Model-integration)을 통해 국방 소프트웨어 테스트 절차 발전 방안에 대해 논의하고, 국방 소프트웨어 품질관리에 대한 청사진을 제시하고자 한다.

• Earthquakes and Structures
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• 제20권2호
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• pp.215-224
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• 2021

The carbon dioxide present in the atmosphere is one of the main reasons for the corrosion of bridges, buildings, tunnels, and other reinforced concrete (RC) structures in most industrialized countries. With the growing use of fossil fuels in the world since the Industrial Revolution, the amount of carbon dioxide in urban and industrial areas of the world has grown significantly, which increases the chance of corrosion caused by carbonation. The process of corrosion leads to a change in mechanical properties of rebars and concrete, and consequently, detrimentally impacting load-bearing capacity and seismic behavior of RC structures. Neglecting this phenomenon can trigger misleading results in the form of underestimating the seismic performance metrics. Therefore, studying the carbonation corrosion influence on the seismic behavior of RC structures in urban and industrial areas is of great significance. In this study, a 2D modern RC moment frame is developed to study and assess the effect of carbonation corrosion, in 5-year intervals, for a 50 years lifetime under two different environmental conditions. This is achieved using the nonlinear static and incremental dynamic analysis (IDA) to evaluate the reinforcement corrosion effects. The reduction in the seismic capacity and performance of the reinforced concrete frame, as well as the collapse probability over the lifetime for different corrosion scenarios, is examined through the capacity curves obtained from nonlinear static analysis and the fragility curves obtained from IDA.

• International Journal of Computer Science & Network Security
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• 제22권7호
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• pp.443-450
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• 2022

The method of studying 3D-technologies abroad and in Ukraine is considered. The analysis of educational resources and experience of use of the equipment in branch is carried out. The didactic principles of the educational process for 3D-printing specialists are determined. The use of FDM technology and the ability to minimize the occurrence of defects in the future have been studied. An analysis of the international experience of the educational process of relevant specialists in the field. The content of training for 3D printing specialists has been developed. The experience of using 3D-technologies is described and the list of recommendations for elimination of defects during production of products by means of additive technologies is made. The recommendations will be useful not only for beginners, but also for experienced professionals in additive technologies. The need to study such experience is the main condition for the development of enterprises in Ukraine that plan to automate their own production. A 3D printing engineer must know the basics of economics and marketing, because his responsibilities include optimizing workflows to reduce the cost and speed up printing. Therefore, the knowledge gained from practical experience presented and in building for learning 3D printing engineers by the authors will be important.

• Advances in nano research
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• 제11권6호
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• pp.581-593
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• 2021

This model is proposed to describe the buckling behavior of Carbon Nanotubes (CNTs) embedded in an elastic medium taking into account the combined effects of the magnetic field, the temperature, the nonlocal parameter, the number of walls. Using Eringen's nonlocal elasticity theory, thin cylindrical shell theory and Van der Waal force (VdW) interactions, we develop a system of partial differential equations governing the buckling response of CNTs embedded on Winkler, Pasternak, and Kerr foundations in a thermal-magnetic environment. The pre-buckling stresses are obtained by applying airy's stress function and an adjacent equilibrium criterion. To estimate the nonlocal critical buckling load of CNTs under the simultaneous effects of the magnetic field, the temperature change, and the number of walls, an optimization technique is proposed. Furthermore, analytical formulas are developed to obtain the buckling behavior of SWCNTs embedded in an elastic medium without taking into account the effects of the nonlocal parameter. These formulas take into account VdW interactions between adjacent tubes and the effect of terms involving differences in tube radii generally neglected in the derived expressions of the critical buckling load published in the literature. Most scientific research on modeling the effects of magnetic fields is based on beam theories, this motivation pushes me to develop a cylindrical shell model for studying the effect of the magnetic field on the static behavior of CNTs. The results show that the magnetic field has significant effects on the static behavior of CNTs and can lead to slow buckling. On the other hand, thermal effects reduce the critical buckling load. The findings in this work can help us design of CNTs for various applications (e.g. structural, electrical, mechanical and biological applications) in a thermal and magnetic environment.

• 한국분말재료학회지
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• 제29권5호
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• pp.363-369
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• 2022

AlSi10Mg alloys are being actively studied through additive manufacturing for application in the automobile and aerospace industries because of their excellent mechanical properties. To obtain a consistently high quality product through additive manufacturing, studying the flowability and spreadability of the metal powder is necessary. AlSi10Mg powder easily forms an oxide film on the powder surface and has hydrophilic properties, making it vulnerable to moisture. Therefore, in this study, AlSi10Mg powder was hydrophobically modified through silane surface treatment to improve the flowability and spreadability by reducing the effects of moisture. The improved flowability according to the number of silane surface treatments was confirmed using a Carney flowmeter. In addition, to confirm the effects of improved spreadability, the powder prior to surface treatment and that subjected to surface treatment four times were measured and compared using s self-designed recoating tester. The results of this study confirmed the improved flowability and spreadability based on the modified metal powder from hydrophilic to hydrophobic for obtaining a high-quality additive manufacturing product.

• 미래기술융합논문지
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• 제2권3호
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• pp.17-24
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• 2023

하이브리드 자동차를 연구로 목적으로 논문을 설계합니다. 히이브리드 자동차는 내연 기관과 배터리 엔진을 동시에 장착하여 기존의 일반 차량에 비해 연비와 유해가스 배출량을 획기적으로 줄인 차세대 자동차로 전기모터는 차량 내부에 장착된 고전압 배터리로부터 전원을 공급받고, 배터리는 자동차가 움직일 때 다시 충전되는 시스템을 가진 차를 연구로 기존 자동차의 에너지 손실은 대부분 교통 혼잡에 따른 공회전을 보완해 차량의 속도나 주행 상태 등에 따라 시간과 차량 정지시 발생하는데 하이브리드 시스템은 이 같은 가솔린 또는 디젤 엔진의 단점엔진과 모터 힘을 적절하게 제어함으로써 효율성을 극대화시킨 차라고 할 수 있다. 하이브리드 차는 연비 개선, 환경 친화성, 경제성, 노이즈 감소 등 다양한 장점을 가지고 있어서 점차 많은 사람들에게 선택되고 있는 대안적인 자동차 옵션입니다. 해당 연구를 통해 환경오염을 방지하고 미래 자동차 연구를 위해 노력을 기울일수 있을 것입니다.

• 한국결정성장학회지
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• 제33권6호
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• pp.276-281
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• 2023

적층제조 공정의 높은 설계자유도에 의해 기존 공정으로 성형이 어려운 형상이 적용된 제품의 제작이 가능해짐에 따라 복잡한 구조를 갖는 기능성 구조에 대한 연구자들의 관심이 증가되고 있다. 타이타늄 합금으로 제작되는 인체 삽입형 임플란트의 경우, 뼈와의 친화성을 확보하기 위해 다차원 격자구조를 적용하여 강도 및 탄성계수를 뼈와 유사한 수준으로 조절하고 있다. 따라서 격자구조의 설계 변수에 따른 기계적 특성에 대한 데이터 베이스 확보 및 관련 시뮬레이션 기술 개발은 개인 맞춤형 인플란트 제작을 효율적으로 수행할 수 있게 할 것이라 생각된다. 따라서 본 연구에서는 Ti-6Al-4V 합금 소재를 적용하여 설계변수별 격자구조체를 제작하고 이에 대한 탄성계수를 측정하였으며 그 결과를 시뮬레이션과 비교하여 정확한 탄성계수 예측을 위한 유한요소해석 방안을 제시하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제12권2호
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• pp.83-90
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• 2008

본 연구는 순환골재의 불순물로 분류되고 있는 부순 적벽돌을 콘크리트용 대체 굵은골재로 사용하기 위한 것이다. 부순 적벽돌 혼입량별(0%, 30%, 60%) 재료실험과 부재실험을 통하여 순환골재가 철근콘크리트에 미치는 재료 및 구조적인 특성을 파악하여 다음과 같은 결론을 얻었다. 일반 쇄석에 대하여 순환골재의 불순물로 분류되고 있는 부순 적벽돌을 혼입률 30%까지 치환하여 사용하여도 일반 쇄석을 사용한 콘크리트와 거의 유사한 압축강도, 인장강도, 휨 강도를 갖는 것으로 나타났다. 따라서 부순 적벽돌을 사용한 철근콘크리트 보의 실제 구조물에 대한 적용이 가능할 것으로 사료된다. 또한, 추후 부순 적벽돌을 사용한 콘크리트의 전단실험 및 연성계수를 향상 시킬 수 있는 혼화재의 배합과 적용에 관한 연구가 필요할 것이다.

• Steel and Composite Structures
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• 제50권5호
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• pp.515-529
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• 2024

Cold-formed steel (CFS) is a popular choice for construction due to its low cost, durability, sustainability, resistance to high environmental and seismic pressures, and ease of installation. The beam-column connections in residential and medium-rise structures are formed using self-drilling screws that connect two CFS channel sections and a gusset plate. In order to increase the moment capacity of these CFS screwed beam-column connections, stiffeners are often placed on the web area of each single channel. However, there is limited literature on studying the effects of stiffeners on the moment capacity of CFS screwed beam-column connections. Hence, this paper proposes a new test approach for determining the moment capacity of CFS screwed beam-column couplings. This study describes an experimental test programme consisting of eight novel experimental tests. The effect of stiffeners, beam thickness, and gusset plate thickness on the structural behaviour of CFS screwed beam-column connections is investigated. Besides, nonlinear elasto-plastic finite element (FE) models were developed and validated against experimental test data. It found that there was reasonable agreement in terms of moment capacity and failure mode prediction. From the experimental and numerical investigation, it found that the increase in gusset plate or beam thickness and the use of stiffeners have no significant effect on the structural behaviour, moment capacity, or rotational capacity of joints exhibiting the same collapse behaviour; however, the capacity or energy absorption capacities have increased in joints whose failure behaviour varies with increasing thickness or using stiffeners. Besides, the thickness change has little impact on the initial stiffness.