• Structural Engineering and Mechanics
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• 제65권3호
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• pp.223-231
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• 2018

A numerical investigation of the impact of steel ductility on the strength and ductility of two-way corner and edge-supported concrete slabs containing low ductility welded wire fabric is presented. A finite element model was developed for the investigation and the results of a series of concurrent laboratory experiments were used to validate the numerical solution. A parametric investigation was conducted using the numerical model to investigate the various factors that influence the structural behavior at the strength limit state. Different values of steel uniform elongation and ultimate to yield strength ratios were considered. The results are presented and evaluated, with emphasis on the strength, ductility, and failure mode of the slabs. It was found that the ductility of the flexural reinforcement has a significant impact on the ultimate load behavior of two-way corner-supported slabs, particularly when the reinforcement was in the form of cold drawn welded wire fabric. However, the impact of the low ductility WWF has showed to be less prominent in structural slabs with higher levels of structural indeterminacy. The load-deflection curves of corner-supported slabs containing low ductility WWF are brittle, and the slabs have little ability to undergo plastic deformation at peak load.

• Nuclear Engineering and Technology
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• 제33권1호
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• pp.93-101
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• 2001

The spacer grid is one of the main structural components in the fuel assembly, which supports the fuel rods, guides cooling water, and protects the system from an external impact load, such as earthquakes. Therefore, the mechanical and structural properties of the spacer grids must be extensively examined while designing them. In this paper, a numerical method for predicting the buckling strength of spacer grids is presented. Numerical analyses on the buckling behavior of the spacer grids are performed for a various array of sizes of the grids considering that the spacer grid is an assembled structure with thin-walled plates and imposing proper boundary conditions by nonlinear dynamic finite element method using ABAQUS/Explicit. Buckling tests on several numbers of specimens of the spacer grid were also carried out in order to compare the results between the test and the simulation result. The drop test is accomplished by dropping a carriage on the specimen at a pre-determined position. From this test, the specimens are buckled only at the uppermost and the lowermost layer among the multi-cells, which is similar to the local buckling at the weakest point of the grid structure. The simulated results also similarly predicted the local buckling phenomena and were found to give good correspondence with the experimental values for the thin-walled grid structures.

• 한국철학논집
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• 제39호
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• pp.195-220
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• 2013

중국 마르크스주의에서 '중국화'와 '대중화'는 언제나 중요한 문제였다. 중국화는 아직까지 꾸준히 강조되고 이론적으로도 발전 했지만, '대중화'는 상대적으로 주목을 덜 받으며 이론적으로 정립된 내용이 많지 않다. 그러나 2007년 중국공산당 제 17차 전국대표대회에서 "당대 중국 마르크스주의 대중화를 추동하자"라는 보고가 제출된 후 중국 학술계에서는 마르크스주의의 대중화와 관련한 다방면의 이론화 작업이 진행 중이다. 중국 마르크스주의 철학사를 통틀어 '마르크스주의의 대중화'를 최초로 제기했고 이 문제에 대해 중국의 마르크스주의 이론가를 망라하여 가장 독보적인 영향을 끼친 사람은 아이쓰치(艾思奇)이다. 아이쓰치의 "대중철학"은 마르크스주의의 대중화와 관련하여 가장 대표적인 책이다. 1930년대 중국은 심각한 위기에 봉착했고 중국의 지식인들과 대중들은 중국을 하나로 묶어 이끌어 줄 수 있는 사상무기를 절박하게 요구하였다. 많은 지식인들이 이들의 요구에 부합하는 것으로 마르크스주의에 주목하였고, 특히 아이쓰치는 마르크스주의 철학의 지도 작용을 어떻게 발휘시킬 것인가, 추상적이며 심오한 철학원리를 어떻게 통속화 대중화 시켜 그것을 광대한 군중들이 장악하고 이용할 수 있도록 만들 것인가 하는 문제를 있는 힘을 다해 고민했던 것이다. "대중철학"은 마르크스주의 철학의 통속화와 중국화라는 특징을 가지고 있으며 책이 출간 된 이후 중국혁명에 지대한 영향을 끼쳤다. 본 논문에서는 "대중철학"을 통해 마르크스주의 철학의 대중화를 고찰해 봄으로써 당대 중국정부가 마르크스주의의 대중화를 다시 강조하는 이유를 파악하고자 했다. 1930년대 아이쓰치의 "대중철학"과 마르크스주의 철학의 대중화 운동이 마르크스주의를 민심을 통일할 수 있는 사회공동체의 학문으로 자리를 잡게 했다면 시장경제의 확대로 인해 혼란과 갈등을 겪고 있는 21세기의 중국공산당도 바로 중국 사회를 통합하려는 목적으로 '중국 마르크스주의 대중화'를 다시 한 번 강조할 수밖에 없었던 것이다.

• Journal of Electrochemical Science and Technology
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• 제15권2호
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• pp.220-241
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• 2024

Due to its unique advantages, electrochemical machining (ECM) is playing an increasingly significant role in the manufacture of difficult-to-machine materials. Most of the current ECM research is conducted at room temperature, with studies on ECM in a cryogenic environment not having been reported to date. This study is focused on the electrochemical dissolution characteristics of typical iron and nickel base alloys in NaNO₃ solution at low temperature (-10℃). The polarization behaviors and passive film properties were studied by various electrochemical test methods. The results indicated that a higher voltage is required for decomposition and more pronounced pitting of their structures occurs in the passive zone in a cryogenic environment. A more in-depth study of the composition and structure of the passive films by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy showed that the passive films of the alloys are modified at low temperature, and their capacitance characteristics are more prominent, which makes corrosion of the alloys more likely to occur uniformly. These modified passive films have a huge impact on the surface morphologies of the alloys, with non-uniform corrosion suppressed and an improvement in their surface finish, indicating that lowering the temperature improves the localization of ECM. Together with the cryogenic impact of electron energy state compression, the accuracy of ECM can be further improved.

• Journal of Plant Biotechnology
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• 제4권3호
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• pp.95-101
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• 2002

Molecular faming has the potential to provide large amounts of recombinant protein for use in diagnostics and as therapeutics. Various strategies have been developed to enhance the expression level, stability, and native folding of recombinant proteins produced in plants. Few investigations into the subcellular distribution of recombinant proteins within plant cells have been published despite the potential to increase the expression level and impact the purification process. This review article discusses the current strategies used for targeting recombinant proteins to various subcellular locations and the advantages of targeting to seed oil bodies for molecular farming applications. Specifically, the affinity capture of antibodies using recombinant oilbodies is discussed.

• Advances in concrete construction
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• 제1권2호
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• pp.137-149
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• 2013

The first part of this two-part paper discussed some basic considerations on bond strength and its effect on strain localization and plastic deformation capacity of cracked structural concrete, and analytically evaluated the impacts of the hardening behavior of reinforcing steel and concrete quality on the basis of the Tension Chord Model. This second part assesses the impacts of the most frequently encountered construction details of existing concrete structures which may not satisfy current design code requirements: bar ribbing, bar spacing, and concrete cover thickness. It further evaluates the impacts of the additional structure-specific features bar diameter and crack spacing. It concludes with some considerations on the application of the findings in practice and an outlook on future research needs.

• The Journal of the Acoustical Society of Korea
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• 제15권1E호
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• pp.39-44
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• 1996

Matched field localization schemes often show a high sensitivity to acoustic variabilities due to mismatch between assumed and actual environments. In this paper, we focus on the effect of source motion or Doppler on matched field processing (MEP). to accomplish this, MFP is extended to treat a moving source problem with normal mode description of the sound field. the extension involves both the temporally nonstationary and spatially inhomogeneous nature of the sound field generated by a time-harmonic point source moving uniformly in a stratified oceanic waveguide. It is demonstrated that the impact of source motion can be significant to MEP although the velocity of a moving source is much smaller than the sound velocity of the oceanic waveguide. In addition, a criteria for minimizing the effect of Doppler on MFP is discussed.

• Smart Structures and Systems
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• 제17권6호
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• pp.1055-1065
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• 2016

An anisotropic ultrasonic transducer is proposed for Lamb wave applications, such as passive damage or impact localization based on ultrasonic guided wave theory. This transducer is made from a PMNPT single crystal, and has different piezoelectric coefficients $d_{31}$ and $d_{32}$, which are the same for the conventional piezoelectric materials, such as Lead zirconate titanate (PZT). Different piezoelectric coefficients result in directionality of guided wave generated by this transducer, in other words, it is an anisotropic ultrasonic transducer. And thus, it has different sensitivity in comparison with conventional ultrasonic transducer. The anisotropic one can provide more information related to the direction when it is used as sensors. This paper first shows its detailed properties, including analytical formulae and finite elements simulations. Then, its application is described.

• 한국소음진동공학회논문집
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• 제20권3호
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• pp.272-278
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• 2010

A method for damage detection in a plate structure is presented based on strain waves that are generated by impact or damage in the structure. Strain responses from continuous sensors, which are long ribbon-like sensors made from piezoceramic fibers or other materials, were used with a neural network technique to estimate the damage location. The continuous sensor uses only a small number of channels of data acquisition and can cover large areas of the structure. A grid type structural neural system composed of the continuous sensors was developed for effective damage localization in a plate structure. The ratios of maximum strains and arrival times of the maximum strains obtained from the continuous sensors were used as input data to a neural network. Simulated damage localizations on a plate were carried out and the identified damage locations agreed reasonably well with the exact damage locations.

• 농촌지도와개발
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• 제1권2호
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• pp.147-163
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• 1994

Agricultural extension programs in Korea had focused mainly on increased production, and the biggest pride of extension was the achievement of rice self-sufficency in 1970s and abundant vegetable and animal production in 1980s. Farming in Korea has changed rapidly in recent years and extension system on commercialized crops have not been satisfactorily developed to mete farmers` demands. Facing the emerging challenges of international competition and trade liberalization for agricultural commodities, the goals of extension should be focused on increased income and the welfare of coral communities. The transfering of agricultural extension educator from central government jobs to local ones has emerged recently under the trends of localization which resulted unstable job environment of extension educator. Intensive pre-service and in-service training of extension workers on current and advanced techologies are essential to upgrade the quality of extension services, and the future directions for professional development of agricultural extension educators in Korea were suggested as follows: 1. Establishing a national network on agricultural extension system to promote exchanges of information among counties and provinces, to conduct meetings and to publish information on agricultural extension. 2. Determining the implications of recent national and global trends on agricultural extension, and strenthening communication at local, national and international levels for an effective extension system in the era of localization, internationalization and globalization; 3. Recognizing the effect of number and quality of extension staff on the impact of extension and providing opportunities development and advancement of extension personnel through education, training, incentives and rewards; 4. Giving a higher priority to agricultural extension in national policies in order to ensure the adequacy of budgetary support and recognition of importance of extension by the ministries concerned and mass communications.