• Computers and Concrete
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• 제17권1호
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• pp.141-156
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• 2016

The search for new structural systems capable of associating performance and safety requires deeper knowledge regarding the mechanical behavior of structures subject to different loading conditions. The Strut-and-Tie Model is commonly used to structurally designing some reinforced concrete elements and for the regions where geometrical modifications and stress concentrations are observed, called "regions D". This method allows a better structural behavior representation for strength mechanisms in the concrete structures. Nonetheless, the topological model choice depends on the designer's experience regarding compatibility between internal flux of loads, geometry and boundary/initial conditions. Thus, there is some difficulty in its applications, once the model conception presents some uncertainty. In this context, the present work aims to apply the Strut-and-Tie Model to nonlinear structural elements together with a topological optimization method. The topological optimization method adopted considers the progressive stiffness reduction of finite elements with low stress values. The analyses performed could help the structural designer to better understand structural conceptions, guaranteeing the safety and the reliability in the solution of complex problems involving structural concrete.

• Computers and Concrete
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• 제17권5호
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• pp.579-596
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• 2016

This paper describes a method of the refined plastic hinge approach in the framework of the higher-order element formulation that can efficaciously evaluate the limit state capacity of a whole reinforced concrete structural system using least number of element(s), whereas the traditional design of a reinforced concrete structure (i.e. AS3600; Eurocode 2) is member-based approach. Hence, in regard to the material nonlinearities, the efficient and economical cross-section analysis is provided to evaluate the element section capacity of non-uniform and arbitrary concrete section subjected to the interaction effects, which is helpful to formulate the refined plastic hinge method. In regard to the geometric nonlinearities, this paper relies on the higher-order element formulation with element load effect. Eventually, the load redistribution can be considered and make full use of the strength reserved owing to the redundancy of an indeterminate structure. And it is particularly true for the performance-based design of a structure under the extreme loads, while the uncertainty of the extreme load is great that the true behaviour of a whole structural system is important for the economical design approach, which is great superiority over the conservative optimal strength of an individual and isolated member based on traditional design (i.e. AS3600; Eurocode 2).

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.297-300
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• 2006

The knowledge of fuel load and composition is important for planning and managing the fire hazard and risk. However, fuel mapping is extremely difficult because fuel properties vary at spatial scales, change depending on the seasonal situations and are affected by the surrounding environment. Remote sensing has potential of reduction the uncertainty in mapping fuels and offers the best approach for improving our abilities. This paper compared the results of object-oriented classification to a pixel-based classification for fuel type map derived from Hyperion hyperspectral data that could be enable to provide this information and allow a differentiation of material due to their typical spectra. Our methodological approach for fuel type map is characterized by the result of the spectral mixture analysis (SMA) that can used to model the spectral variability in multi- or hyperspectral images and to relate the results to the physical abundance of surface constitutes represented by the spectral endmembers. Object-oriented approach was based on segment based endmember selection, while pixel-based method used standard SMA. To validate and compare, we used true-color high resolution orthoimagery

• 대한기계학회논문집A
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• 제25권11호
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• pp.1863-1872
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• 2001

In this Paper, we suggest the precision stage using a novel non-contact planar actuator that utilizes an interaction between an array type of air-core solenoids and permanent magnets. The former with axes arranged in the mutually orthogonal direction is fixed on the stator and the latter with the same polar direction is attached below the stage. The promising magnetic structure has little uncertainty such as hysteresis loss caused by ferromagnetic material, then it is simple to quantify the magnetic phenomenon. And all the magnetic forces are transmitted through narrow air-gap between the coil and the permanent magnet, therefore the structure can be highly compacted. Furthermore, the stage or plate can be perfectly isolated from the stator without any wire connection, leading to diminish the generating possibility of wear particles due to mechanical contact. Then. it is estimated that the proposed operating principle is very suitable for work requiring high accuracy and cleanness. or general-purpose nano stage. The main issues rebated to the plate driving are discussed here.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2001년도 제16회 학술발표회 논문초록집
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• pp.91-94
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• 2001

A structural test of the wind turbine rotor blade must be required to evaluate the uncertainty in design assessment due to use of material, design concepts, production processes and so on, and the possible impact on the structural integrity. In the full-scale static strength test, the measuring parameters are strain, displacements, loads, weight and the center of gravity. There are test equipments, measuring sensors, a test rig and fixtures to obtain measuring parameters. In order to simulate the aerodynamics load, the three-point loading method instead of the one-point loading method is applied. There is slightly some difference between the measured results and the predicted results with the reference fiber volume fraction of 60%. However, the agreement between the measured results and the predicted results with the actual fiber volume fraction of 52.5% is good. Even though a slightly non-linearity from 80% loading to 100% loading, a linear static solution is sufficient for the design purpose as the amount of the non-linearity is relatively small. Comparison between measured and predicted strain results at the maximum thickness positions of the blade profile for 0.236R(5.56m), 0.493R(11.59m) and 0.574R(13.43m), under 20%, 40%, 60%, 80% and 100% loadings for the upper part of the blade. The predicted values are in good agreement with the measured values.

• 플랜트 저널
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• 제7권2호
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• pp.39-43
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• 2011

Due to the recent uncertainty of market situations such as the escalation of petroleum prices, increased production capacities of plants, limitations of the available EPC (Engineering, Procurement, Construction) contractors, and the increase of raw material prices, EPC contractors have had a tendency to include a higher reserve contingency in the lump-sum turnkey contract price. In order to overcome the changes in the market, the plant project construction industry has started to apply the converted lump-sum turnkey contract in plant construction market. This study was focused to find the associated risks and to analyse the identified risks on recent trend of application of the new contract type, which is the converted lump-sum turnkey contract. It was recognized from the analysis that quality and cost have more high priority risks than other project objectives. This paper also suggests the mitigation plan for identified risks to achieve project objectives appropriate to the converted lump-sum turnkey project from the viewpoint of an EPC contractor keeping transparency with owner.

• 유통과학연구
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• 제13권5호
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• pp.23-31
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• 2015

Purpose - This study investigated competitive counteractions necessary for continuous growth in a rapidly changing logistics environment in Northeast Asia. Research Design, Data, and Methodology - Using a time series analysis, the study first investigated Northeast Asian trade scale and volume by examining online and offline material from the Ministry of Ocean and Fisheries, Busan Port Authority, and other government agencies. A literature survey was done to investigate the state and prospect of the logistics environment in Northeast Asia including changes in freight volume at major ports in the three Northeast Asian countries. Result - The results of the study suggest using the Trans-Korean Railroad (TKR), as well as promoting the North Pole and South Pole routes, to compete against changes in trade volume and the logistics environment in Northeast Asia. A SWOT analysis was done to examine the effectiveness of these strategies. Conclusions - The findings indicate that the TKR impact, using the Busan Port connecting the Trans-China Railway (TCR), the Trans-Siberian (TSR), and the North Pole Route, may be uncertain in practice considering the uncertainty in international politics.

• 분석과학
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• 제15권4호
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• pp.335-340
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• 2002

유도결합 플라스마 질량분석법 (ICP-MS)을 이용하여 모발 중 다원소 동시 정량법을 확립하였다. 0.05 g의 모발 시료에 내부표준물질인 In을 가하고 질산 1.5 mL와 함께 테플론 가압분해 용기에 넣어 마이크로파를 이용하여 분해하는 시료전처리법을 사용하였다. 측정값의 정확도 및 신뢰도를 확인하기 위하여 모발 인증표준물질인 GBW 09101을 반복 분석하였는데 측정값은 인증값과 불확도 범위 내에서 잘 일치하는 결과를 얻었다.

• 한국정밀공학회지
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• 제18권10호
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• pp.154-160
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• 2001

For major structural components periodic inspections and integrity assessments are needed for the safety. However, many flaws are undetectable because sampling inspection is carried out during in-service inspection. Probabilistic integrity assessment is applied to take into consideration of uncertainty and variance of input parameters arise due to material properties and undetectable cracks. This paper describes a Probabilistic Fracture Mechanics(PFM) analysis based on the Monte Carlo(MC) algorithms. Taking a number of sampling data of probabilistic variables such as fracture toughness value, crack depth and aspect ratio of an initial surface crack, a MC simulation of failure judgement of samples is performed. for the verification of this analysis, a comparison study of the PFM analysis using a commercial code, mathematical method is carried out and a good agreement was observed between those results.

• 한국항공우주학회지
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• 제43권10호
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• pp.896-901
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• 2015

온도 구배에 의한 날개 외피의 열변형 특성을 연구하기 위하여 비행체 날개의 포켓 형상을 본 딴 프레임 외피 구조 시편을 제작하였다. 날개에 발생하는 온도 구배 현상을 효과적으로 모사하기 위하여 프레임 외피 시편의 프레임에 수냉 시스템을 개발, 적용하였다. 공력 특성에 영향을 미치는 날개 외피의 면외 열변형을 정량적으로 평가하기 위하여 디지털 영상 상관 기법(Digital Image Correlation technique, DIC)을 사용하고, 면외 변위 측정 불확도 평가를 통해 측정 정확도를 분석하였다. SUS304 소재로 만들어진 프레임 외피 구조 시편의 시험을 수행하여 온도에 따른 외피의 면외 변형 특성을 성공적으로 획득하였다.