• Computers and Concrete
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• 제22권1호
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• pp.83-91
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• 2018

Various systems for simulating particulate matter are developed and used in concrete technology for producing virtual cementitious materials on the different levels of the microstructure. Basically, the systems can be classified as two distinct families, namely random sequential addition systems (RSAs) and discrete element methods (DEMs). The first type is hardly being used for this purpose outside concrete technology, but became popular among concrete technologists. Hence, it is of utmost relevance to compare the two families in their capabilities, so that the reliability of produced data can be estimated. This paper pursues to do this on the basis of earlier published material of work performed by a succession of PhD students in the group of the second author. Limited references will be given to external sources.

• 한국세라믹학회지
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• 제49권1호
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• pp.19-28
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• 2012

High-energy mechanical action applied to solid leads to destruction and diminution to the nanosize level. But on the other hand, it can induce structural changes at the nanoscale and at the atomic level which can result in novel materials properties. In this contribution, case studies will be presented concerned with the tailoring of magnetic properties of mechanically treated nanomaterials. Emphasis is placed on materials that have been synthesized by mechanochemical means and on an improved understanding of their nanomagnetism in general. The associated local structural changes of the iron containing magnetic materials discussed in the examples have been studied most suitably by $^{57}Fe$ Mossbauer nuclear probe spectroscopy whose results are supplemented by measurements of the magnetic properties of the mechanosynthesized nanomaterials.

• 한국가구학회지
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• 제22권2호
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• pp.118-125
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• 2011

These days global warming is the most important problem and the most important factor is high emission of carbon dioxide. The 23% of carbon dioxide emission for building construction must be reduced. Thermal conductivity is the most basic factor that can decrease the energy consumption especially insulation. Therefore, an accurate and continuous thermal conductivity measurement can be a way to save energy. In this paper, there are methods about how to investigate thermal conductivity measurements and comparing two methods which are the Heat Flow Meter 436 and TCi.

• Applied Microscopy
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• 제42권4호
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• pp.218-222
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• 2012

Modern aberration-corrected transmission electron microscope (TEM) with appropriate electron beam energy is able to achieve atomic resolution imaging of single and bilayer graphene sheets. Especially, atomic configuration of bilayer graphene with a rotation angle can be identified from the direct imaging and phase reconstructed imaging since atomic resolution Moir$\acute{e}$ pattern can be obtained successfully at atomic scale using an aberration-corrected TEM. This study boosts a reliable stacking order analysis, which is required for synthesized or artificially prepared multilayer graphene, and lets graphene researchers utilize the information of atomic configuration of stacked graphene layers readily.

• Tribology and Lubricants
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• 제25권3호
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• pp.182-186
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• 2009

Extruders can be basically divided into bisk and screw type of extruders. Though plastic extruders are often used for its simplicity for water and oil transportation pumps, these days screw extruders are mostly used. Screws are used in many extrusion processes to manufacture complex and complicated shaped parts made of plastics, medicine materials, food, polymer composites, iron and ceramic powders, etc. Also, material correction of deformities is caused by flow and physicochemical reaction phenomenonand material extrusion is processed according to heat transfer. various material comes to hopper because extruder has function by blender and mixing of materials can go well before come out through dice. These change process is so complicated that process condition is decided by trial and error that process condition is underground mainly at extrusion molding process.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.440-440
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• 2012

The optical characteristics of transparent electrode with various kind of materials and thickness to be used for organic photovoltaic cells were studied by simulation methodology. It demonstrated that the transmittance varies with the kinds of materials, the number of layers and change in the thickness of each layer. In the case of the structure composed of dielectric/Ag/dielectric, optimized transmittance was higher than 90% at 550 nm and the thickness of the Ag layer was ~10nm. Top and bottom dielectric materials can be changed with different refractive index and extinction coefficient. The relation between the optical transmittance of device and transparent electrode with different refractive indices was discussed as well. By processing numerical simulations, an optimized optical transmittance can be obtained by tunning the thickness and materials of transparent electrode.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.367-374
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• 2005

In order to construct the farm road in Shi-Hwa project, coarse soils excavated from hillsides have been used as road materials for reclamation. Suitable borrow pits available in land are now limited and also they bring about environmental problems when soils are excavated at the borrow pits and transported to the site. When using fine and wet materials as fill, however, many engineering problems can be encountered. Usually, the materials have high water contents, low strength, and high compressibility. In order to use them, we need research that can improve the inherent properties of those materials. In order to tackle with the problems, researches on soil improvement involve mixing lime geo-cement to the fine wet soils. A lab model test is necessary to verify effectiveness and comparison of those techniques. A field test is also required to show applicability and to find problems that may exist in the design and construction stages.

• 로봇학회논문지
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• 제11권4호
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• pp.235-241
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• 2016

Dual arm manipulators have been developed for the entertainment purpose such as humanoid type or the industrial application such as automatic assembly. Nowadays, there are some issues for applying the dual arm robot system into the various fields. Especially, robots can substitute human and perform the dangerous activity such as search and rescue in the battle field or disaster. In the paper, the dual arm manipulator which can be adapted to the rescue robot with the mobile platform was developed. The kinematic design was proposed for the rescue activity and the required specification was determined through the kinematic analysis and the dynamic analysis in the various conditions. The proposed dual arm manipulator was manufactured based on the vibration analysis result and its performance was proved by the experiment.

• ETRI Journal
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• 제31권6호
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• pp.709-716
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• 2009

In this paper, we propose a novel reconfigurable processor using dynamically partitioned single-instruction multiple-data (DP-SIMD) which is able to process multimedia data. The SIMD processor and parallel SIMD (P-SIMD) processor, which is composed of a number of SIMD processors, are usually used these days. But these processors are inefficient because all processing units (PUs) should process the same operations all the time. Moreover, the PUs can process different operations only when every SIMD group operation is predefined. We propose a processor control method which can partition parallel processors into multiple SIMD-based processors dynamically to enhance efficiency. For performance evaluation of the proposed method, we carried out the inverse transform, inverse quantization, and motion compensation operations of H.264 using processors based on SIMD, P-SIMD, and DP-SIMD. Experimental results show that the DP-SIMD control method is more efficient than SIMD and P-SIMD control methods by about 15% and 14%, respectively.

• 한국군사과학기술학회지
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• 제13권6호
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• pp.1153-1171
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• 2010

Hydrogen is the most abundant element in the universe. Although hydrogen can produce three times more energy than gasoline and seven times than coal, the most challenging problem in utilizing hydrogen as energy carrier is its storage problem. In contrast to the liquid hydrocarbon, hydrogen can not be stored or transported easily and safely because of its extremely low boiling point(21K). Recently scientists have made a tremendous achievement in storing hydrogen capacity in solid state materials such as carbon based and metal organic frameworks materials as well as metal hydrides. In this review the author reviewed the status of the hydrogen storage technologies in solid state, the advantages and disadvantages in each category of materials and the future prospects of hydrogen storage.