• Transactions of Materials Processing
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• v.16 no.6
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• pp.473-478
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• 2007

In this study, a deformation mechanism map of metallic nanocrystalline materials(NCMs) using the phase mixture model is proposed. It is based on recent modeling that appears to provide a conclusive description of the phenomenology and the mechanisms underlying the mechanical properties of NCMs. The proposed models adopted the concept of a 'phase mixture' in which the grain interior and the grain boundaries are treated as separate phases. The volume fraction of this grain boundary 'phase' may be quite appreciable in a NCM. Based on the theoretical model that provides an adequate description of the grain size dependence of plasticity covering all grain size range from coarse down to the nanoscale, the tensile deformation response of NCMs, especially focusing on the deformation mechanisms was investigated. The deformation mechanism map is newly proposed with axes of strain rate, grain size and temperature.

• Journal of the Korean Ceramic Society
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• v.55 no.4
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• pp.325-336
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• 2018

Perovskite solar cells (PSCs) are a new class of photovoltaic devices, which have attracted significant attention due to their remarkable optoelectrical properties, including high absorption coefficients, high carrier mobilities, long carrier diffusion lengths, tunable bandgaps, low cost, and facile fabrication. PSCs have reached efficiencies of 22.70% and 18.36% on rigid fluorine-doped tin oxide and poly(ethylene terephthalate) substrates, respectively; these are comparable to those of single-crystal silicon and copper-indium-gallium-selenium solar cells. Over the past eight years, the photo conversion efficiency of PSCs has been significantly improved by device-architecture adjustments, and absorber and electron/hole transport layer optimization. Each layer is important for the performance of PSCs; hence, we discuss achievements in flexible perovskite solar cells (FPSCs), covering electron/hole-transport materials, electrode materials. We give a comprehensive overview of FPSCs and put forward suggestions for their further development.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.326-331
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• 2009

This study was carried out to evaluate the effects of row cover materials supported by flexible FRP frames with three kinds of non-woven fabric, and five kinds of net in leaf vegetable cultivation. Leaf radish (Raphanus sativus L.), Chinese cabbage (Brassica rapa L. ssp. pekinensis) were sown on May 21, 2003, and leaf lettuce (Lactuca sativa L.) was planted at the same date in Agricultural Research Center for Climate Change, Jeju, Korea. Net coverings showed higher light transmittance than in non-woven fabric coverings. The average air and soil temperatures increased by $0.3{\sim}1.0^{\circ}C$ in net coverings and $0.5{\sim}3.0^{\circ}C$ in non-woven fabric coverings, respectively. There was no difference in relative humidity among the covering materials. All the vegetables showed higher growths and yields in non-woven coverings than in non-covering. The yields increased 81% in leaf lettuce, 58% in leaf radish, and 93% in Chinese cabbage, respectively. In addition, the insect damages were considerably reduced in the row covering plots than in the control, especially in non-woven fabric coverings.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.77-83
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• 2010

In this study, we analyzed the combustion characteristics of four different floor covering materials(wood, monorium, laminatedpaper, and varnish-laminated paper) with regard to their ignitibility, thermal characteristics and flame retardancy by using an ignition temperature tester, a dual cone calorimeter, a thermogravimetric analyzer and limited oxygen index, for their fire risk assessment. According to the result, monorium had the lowest ignition temperature of $325^{\circ}C$ and the laminated paper and the varnish-laminated paper promptly ignited before 7s. Further, the wood showed the largest total heat release of $100MJ/m^2$, and the varnish-laminated paper showed the highest peak heat release rate. From the thermogravimetric analysis, it was shown that all specimens underwent rapid weight loss at $300{\sim}400^{\circ}C$. The limit oxygen indices of the laminated paper and the varnish-laminated paper were in the range of 20~21%, while it was 34% for wood. This study enabled us to confirm that wood, laminated paper and varnish-laminated paper have a relatively short ignition time and are easy to burn but they all have low heat release. In contrast, wood showed the lowest fire risk among them and had excellent flame retardancy but with high heat release.

• Journal of Bio-Environment Control
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• v.19 no.1
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• pp.1-5
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• 2010

This research was conducted to investigate difference of internal temperature, humidity, and plant growth according to covering materials in sweet pepper's greenhouse. For growing period, daily mean internal temperature was not different between glass (GH) and plastic film house (PH), but the changed volume was more PH than GH. Internal humidity deficit was more PH than GH as that was 4.3 $g{\cdot}m^{-2}$ and 5.6 $g{\cdot}m^{-2}$, respectively. In change of internal temperature effected by different intensity of external light, that of PH was fasted twice that of GH, and that's tendency was effected by difference of internal temperature for several hours after sunrise. Leaf growth and photosynthetic product were more GH than PH, productivity of GH was better 80 percents than PH. As results, To improve productivity in PH compared with productivity in GH need to be the detailed managements of internal environmental factors in early period after sunrise.

• Korean Journal of Medicinal Crop Science
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• v.2 no.1
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• pp.14-19
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• 1994

Elephant food(Amorphophallus konjac K.) have been utilized its tubers in workedmaterials for a health and diet food. The author supposed that it was increased the area of cultivation and demand. This experiments were conducted to select the proper covering material during winter in order to increase yield of tubers and decrease input by 2 year's continuous cultivation, also to verified ability of seed germination and to measured efficiency of photosynthesis of plant. The proper covering materials for wintering were rice straw and rice hull. These materials were covered at 5 cm thick and at field was promoted according to emergence appearing after winter. The yields were 5,790kg /10a at 4,730kg /10a, respectively. Yield increase was 120% and 80% than that of control. The seeds collected at August 22 were germinated about 84 percent, and it was not necessary to treatment of low temperature or germination-accelerated chemicals. The widest leaf area was ranged $1,218-1,438cm^2$ at October 20 and was varied. The efficiency of photosynthesis was highest at 65-95 days after leaf emergence. The line of broad leaf and high photosynthetic efficiency per unit area was greater compare with yield. Therefore, it was supposed that these characteristics will use a marker for selection for high-yielding lines.

• Computers and Concrete
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• v.32 no.6
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• pp.567-576
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• 2023

In this study, a 3D microstructure-based model is established to simulate the effective thermal conductivity of cement paste, covering varying influencing factors associated with microstructure and thermal transfer mechanisms. The virtual cement paste divided into colloidal C-S-H and heterogeneous paste are reconstructed based on its structural attributes. Using the two-level hierarchical cement pastes as inputs, a lattice Boltzmann model for heat conduction is presented to predict the thermal conductivity. The results suggest that due to the Knudsen effect induced by the nanoscale pore, the thermal conductivity of air in C-S-H gel pore is significantly decreased, maximumly accounting for 3.3% thermal conductivity of air at the macroscale. In the cement paste, the thermal conductivities of dried and saturated cement pastes are stable at the curing age larger than 100 h. The high water-to-cement ratio can decrease the thermal conductivity of cement paste.

• Korean Institute of Interior Design Journal
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• no.34
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• pp.29-36
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• 2002

Skin Architecture', which has been an important topic of architectural discourse in the recent past, is playing an even greater role in the design expression of architectural materials nowadays. The purpose of this study is to define the epidermal conception about material matter and to discover the various modes of visual effect in the use of architectural materials.Epidermal thought is expressed in different forms, ranging from a simple covering made up of materials of all kinds , removable or technological wrappings. Analyzing the recent experiments from the works of Bernard chumi, Herzog & de Meuron, Peter Zumthor, Gigon & Guyer , it can be argued that the skin is a good emotional approach in the design expression of architectural material matter as epidermal concept since the 1980's.

• Journal of Fashion Business
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• v.5 no.5
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• pp.65-76
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• 2001

The hat is the most flexible human head covering. Almost entirely enveloping the hair, it can be simple, pure, elegant and mysterious. Yet it is frequently a highly decorative form of dress. The hat also takes a part in the extension of the area of art as soft-sculpture. My purpose of this thesis is to present diverse artistic hats with natural images by nontraditional materials and natural resources. The reason why I select nature as them is that it is absolutely the origin of life and art. To develop the innovative hat design, I focus on the material to extend the range of art expression. I observe nontraditional materials such as wire, paper and so on that enhance heterogenetic feeling from natural images. The attempt is made to enhance the visual effect by harmonizing the disharmonious feeling. Natural resources such as moss, orange, feather and so on could be adapted to the hat and applied for unique design, which supplies new expression. Therefore, the harmony of natural images and natural resources could avoid dullness, bestow elegance and polish the unique beauty creation of the hat.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.1-1
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• 1992

Shape Memory Alloys have attracted the interest of a great number of researchers in the world, and Mexico is not the exception. Research in this field started ten years ago, and is actually an active line covering the classical Cu-based and Ti-Ni alloys, but also the new Fe-based alloys. Although more basic studies have been performed at the present time, interest for applied research and technological goals is increasing. In this work we present a series of studies carried on these Shape Memory Alloys by the groups in Mexico, and explain what the interest of our groups are in the next future in this are of the Materials Science. Interdisciplinary work has been necessary in the characterization of the different alloys, and multiple techniques have been used, like Mossbauer spectroscopy, thermoelectric power, electron microscopy, ultrasound techniques, neutron and x-ray diffraction, calorimetry, among others. Collaboration With other groups in Europe and in the United States have become highly useful and productive, and some examples of such activities are also reported.