• Structural Engineering and Mechanics
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• 제78권1호
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• pp.67-75
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• 2021

This work studies the behaviour of a steel portal frame selection under fire exposure, considering both span lengths and fire exposure times as variables. Such structures combine carbon steel (S275), fireproof micro-alloyed steel (FR), and coatings of intumescent paint with variable thicknesses, improving thereby the flame retardant behaviour of the steel structure. Thus, the main contribution of this study is the optimization of the portal frames by combining both steels, analysing the resulting costs influence on the final dimensions. Besides, the topological optimization of each steel component within the structure is also defined, in accordance with the following variables: weather conditions, span, paint thickness, and cost of steel. The results mainly confirmed that using both FR and S275 grades with intumescent painting is the Pareto optimum when considering performance, feasibility and costs of such portal frames widely used for industrial facilities.

• Earthquakes and Structures
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• 제13권3호
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• pp.241-253
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• 2017

In this paper, dynamic response of the horizontal nanofiber reinforced polymer (NFRP) strengthened concrete beam subjected to seismic ground excitation is investigated. The concrete beam is modeled using hyperbolic shear deformation beam theory (HSDBT) and the mathematical formulation is applied to determine the governing equations of the structure. Distribution type and agglomeration effects of carbon nanofibers are considered by Mori-Tanaka model. Using the nonlinear strain-displacement relations, stress-strain relations and Hamilton's principle (virtual work method), the governing equations are derived. To obtain the dynamic response of the structure, harmonic differential quadrature method (HDQM) along with Newmark method is applied. The aim of this study is to investigate the effect of NFRP layer, geometrical parameters of beam, volume fraction and agglomeration of nanofibers and boundary conditions on the dynamic response of the structure. The results indicated that applied NFRP layer decreases the maximum dynamic displacement of the structure up to 91 percent. In addition, using nanofibers as reinforcement leads a 35 percent reduction in the maximum dynamic displacement of the structure.

• Smart Structures and Systems
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• 제24권2호
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• pp.193-207
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• 2019

This study concerns with morphing structures, e.g. as applied in the aerospace industry. A morphing aerofoil structure capable of variable geometry was developed, which was shown to be able to cater for the different aerodynamic requirements at different stages of flight. In this work, the useful and relatively simple method has been applied, which provides a direct method for calculating required morphing shape displacements via finding the most effective bar through calculating bar sensitivity to displacement and calculating set of length actuations for bar assembly to control/adjust shape imperfection of prestressable structural assemblies including complex elements ("macro-elements", e.g., the pantographic element), involving Matrix Condensation. The technique has been verified by experiments on the physical model of an aerofoil shaped morphing pantographic structure. Overall, experimental results agree well with theoretical prediction. Furthermore, the technique of multi-iteration adjustment was presented that effective in eliminating errors that occur in the practical adjustment process itself. It has been demonstrated by the experiments on the physical model of pantographic morphing structure. Finally, the study discusses identification of the most effective bars with the objective of minimal number of actuators or minimum actuation.

• 한국주거학회논문집
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• 제20권5호
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• pp.61-72
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• 2009

The purpose of this study was to examine how the interface between "place of work" and "place of living" in the housing sphere has changed, and to understand its social background. During the korean modernization period, changes in economic structure toward industry has an influence on many aspects of modem life in addition to occupations. The traditional mixing of heterogeneous activities in the home-such as between reproduction and household affairs, first changed into a coexistence of two spaces with different functions within the boundaries of home, and finally into a spatial separation between functions in an urban dimension. As a result of this process, the primary role of the modem home is as a place for relaxation without work. One important kind of home, in which a retail shop is integrated with it, was researched as a transitional form. Its spatial layout showed a various combined usage of both spaces. In conclusion, changes in relevant macro-social aspects are very concretely reflected m the function and spatial organization of the home.

• 대한건축학회논문집:구조계
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• 제36권4호
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• pp.163-172
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• 2020

In this study, the effect of window opening, which is a control mechanism for air control in winter high school classrooms, on the change in air and indoor environment of the classroom was analyzed and physical conditions of indoor and air environment were observed during the classroom course, and satisfaction of the students and teachers was assessed with questionnaires. And the changes in air environment were assessed by the performance of the duster cleaning work in the classroom. It was found that 84.6% of the students surveyed said the air was stuffy. And among the alternatives, opening windows all times during class was most effective in reducing CO₂ concentration and PM concentration was measured within classroom's standard. In addition, the concentration change rate of duster cleaning work was reduced by 74.4% and 65.4% of PM10 compared to broom cleaning work.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.118-120
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• 2022

본 논문은 M3D(Monolithic 3-Dimension) Inverter의 소자 구조에서 메탈 게이트의 WFV(Work-function Variation)의 영향에 따른 임계전압의 변화에 대하여 조사했다. 또한 PMOS 위에 NMOS가 적층된 인버터의 전기적 상호작용에 따른 임계전압의 변화를 조사하기 위해 PMOS에 0과 1 V의 전압을 인가하여 전기적 상호작용을 조사하였다. 사용된 메탈 게이트의 평균 일함수에 대한 임계전압의 변화량은 0.1684 V로 측정되었고, 표준편차는 0.00079 V가 조사 되었다.

• Smart Structures and Systems
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• 제22권1호
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• pp.95-103
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• 2018

Active vibration control via inertial mass actuators has been shown as an effective tool to significantly reduce human-induced vertical vibrations, allowing structures to satisfy vibration serviceability limits. However, a lot of practical obstacles have to be solved before experimental implementations. This has motivated simple control techniques, such as direct velocity feedback control (DVFC), which is implemented in practice by integrating the signal of an accelerometer with a band-pass filter working as a lossy integrator. This work provides practical guidelines for the tuning of DVFC considering the damping performance, inertial mass actuator limitations, such as stroke and force saturation, as well as the stability margins of the closed-loop system. Experimental results on a full scale steel-concrete composite structure (behaves similar to a footbridge) with adjustable span are reported to illustrate the main conclusions of this work.

• 수산해양교육연구
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• 제28권2호
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• pp.407-416
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• 2016

The offshore plant industry has basically functioned with a rigid teamwork culture and many operations are managed by ship's crew, shifts and affiliates together. The marine sector of offshore plant has much similarity with ship's environment. So a person who had experienced on board will have advantages to work for offshore industry. But in spite of all that, only a few korean seafarers are able to join in the offshore industry due to lack of information about the offshore environment. This study analyze the employee's wage structure, nature of employment contract, requirements of job qualifications. Therefore, this study will assist for seafarers to set up how to get their work and also suggest to develop relevant offshore training courses by researching the gap competency matrix.

• 한국기계기술학회지
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• 제20권6호
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• pp.894-900
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• 2018

Among the soft ground improvement methods, PBD is the most common construction method because it is cheap and construction is fast. However, if the ground is rigid, additional work is required. In this study, the structural safety, natural vibration, and safety angle of the steel vertical tower structure were evaluated in the development of the PBD composite perforator which can be combined with drilling work and PBD construction. Structural safety was assessed when the wind load of 20 m/s was simultaneously applied to the PBD construction load of 20 tons, the perforating operation of 25 tons, and the wind speed of 50 m/s was applied only to the wind load. The natural frequencies were evaluated up to the sixth mode, and the safety angle was evaluated for static and dynamic safety angles.

• 문화기술의 융합
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• 제8권3호
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• pp.43-50
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• 2022

<잊혀진 영상>은 클로드 드뷔시(Claude Debussy)의 피아노 독주곡으로서 1894년에 작곡되었으나 미상의 이유로 1977년이 되어서야 비로소 출판되었다. 흥미롭게도 총 세 곡으로 구성된 작품 중 제 2곡은 1896년 2월 파리의 일간지 '르 그랑 저널(Le Grand Journal)'을 통해 독립적으로 발표되었으나, 제 1곡과 3곡은 자필 악보 상태로 남아 있다가 1977년 뒤늦게 출판되었다. 이러한 이유로 본 작품은 아직까지도 피아노 연주가들과 음악 애호가들에게 잘 알려지지 않은 작품으로 남아있다. 이에 본 논문에서는 이러한 작품의 출판 시기, 작곡 배경에 대해 먼저 고찰해보고, 작품의 작곡 양식적 특징을 선율, 화성, 형식의 측면에서 면밀하게 분석하여 본다. 본 작품을 구성하는 세 곡은 다양한 교회 선법, 온음음계 그리고 전통적 조성 체계의 회피를 통한 화성적 어법의 확대를 보여주며 드뷔시가 피아노 독주곡에 즐겨 적용하였던 3악장 구성의 틀을 제시한 최초의 작품으로 볼 수 있다. 이러한 드뷔시 피아노 독주곡 양식에 대한 음악어법상의 이해와 함께, 잘 알려지지 않은 본 곡이 차지하는 음악사적인 가치에 대한 관심이 증대될 것을 기대한다.