• Steel and Composite Structures
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• v.50 no.1
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• pp.107-122
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• 2024

Following an internal column failure, adjacent double-span beams above the failed column will play a critical role in the load transfer and internal force redistribution within the remaining structure, and the span-to-depth ratios of double-span beams significantly influence the structural resistance capacity against progressive collapse. Most existing studies have focused on the collapse-resistant performances of single-story symmetric structures, whereas limited published works are available on the collapse resistances of multi-story steel frames with unequal spans. To this end, in this study, numerical models based on shell elements were employed to investigate the structural behavior of multi-story steel frames with unequal spans. The simulation models were validated using the previous experimental results obtained for single- and two-story steel frames, and the load-displacement responses and internal force development of unequal-span three-story steel frames under three cases were comprehensively analyzed. In addition, the specific contributions of the different mechanism resistances of unequal-span, double-span beams of each story were separated quantitatively using the energy equilibrium theory, with an aim to gain a deeper level of understanding of the load-resistance mechanisms in the unequal-span steel frames. The results showed that the axial and flexural mechanism resistances were determined by the span ratio and linear stiffness ratio of double-span beams, respectively.

• Journal of the Korean Wood Science and Technology
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• v.27 no.1
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• pp.88-104
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• 1999

This study was carried out to classify the Hanjis into three groups that were indigenous Hanji, traditional Hanji, and improved Hanji handmade by paper making method according to the physical properties of each paper sheet such as tensile, bursting and tearing strength, folding endurance and fiber orientation in each layer. The results obtained were summarized as follows: 1. The multi-layered Hanjis made by "Oebal" Hanji making method in different direction of fiber orientation have good properties in tearing resistance. 2. The multi-layered Hanji in different direction of fiber orientation has good properties in the tearing resistance, but the burst index and the breaking length results were lower than the single layered Hanjis. 3. The different fiber orientation and multi-layered method didn't increase, the three indexes(burst index, tear index, breaking length). Only, the different direction of fiber orientation decreased the difference of width and length strength (tensile, tear) of the Hanji. 4. "Dochim"(Korean finishing touch process for indigenous Hanji by fulling round sticks) greatly increase folding endurance(double folds, not $log_{10}$) and good effect to tensile strength and burst strength. 5. The today's Oebal Hanji were the maximum of 2 layers and the indigenous Oebal Hanji were 16 layers the maximum. In addition, average of the indigenous Oebal Hanji was 4 layers(all 4-layer Hanji were the different fiber orientation of each layer). 6, The indigenous Hanji(multi-layered, and different fiber orientation) was good condition with "Dochim". Dochim increased tensile strength and burst strength of the indigenous Hanji. So the three-strength indexes were similar level("--"). 7. When the number of layer which were same fiber orientation increase, the increased Hanji became similar strength pattern("V", breaking length and burst index was higher than tear index) with "Ssangbal" Hanji. 8. The single layered papers that made by "Oebal" Hanji making method were similar strength pattern with Ssangbal Hanji. 9. There was no way to find the width and length direction of multi-layered Hanji by comparison between the difference of tensile strength and the difference of tearing resistance. 10. The compared pattern of tensile strength and tearing resistance of indigenous Oebal Hanji was different from today's Oebal Hanji. Especially, the tearing resistance of all indigenous Oebal Hanji(16 samples) was stronger on width of tearing resistance. And in the half of indigenous Oebal Hanji samples, the width of tensile strength and tearing resistance was stronger than length strength (Indigenous Oebal: '$\ulcorner\lrcorner$' 50%, '$\bigcup$' 50% $\leftrightarrow$ Today's Oebal: '$\ulcorner\lrcorner$' 12%, '$\bigcup$'6%, '$\llcorner\urcorner$'17%, '$\bigcap$'65%). In 65% today's Oebal, the length direction of tensile strength and tearing resistance was stronger than the width direction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.859-864
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• 2000

Recently IR detecting devices using MEMS have been actively studied. Microbolometer, one of these devices, detects the change of resistivity as the change of temperature of the device by absorbing IR, IR absorbing materials for microbolometer should have high TCR value and low noise characteristics which depends on resistivity. We fabricated multi-layer VOx thin films to improve the IR detectivity of uncooled IR devices and analyzed IR absorbing characteristics. We fabricated multi-layer VOx thin films by RF reactive sputtering method on SiNx substrate and changed characteristics using the different thickness of V and V$_2$O$\_$5/ thin films. Then we annealed them under 300$\^{C}$. The TCR (Temperature Coefficient of Resistance) measurement was carried out to estimate the IR detectivity of multi-layer VOx thin films. XRD (X-Ray Diffraction) analysis was carried out to estimate the IR detectivity of multi-layer VOx thin films. ZXRD (X-Ray Diffraction) analysis was used to find out phases and structures of V and V$_2$O$\_$5/ thin films. AES (Auger Electron Spectroscopy) analysis was used to find out composition of multi-layer VOx thin films before and after annealing. We obtained the optimum thickness range of V and V$_2$O$\_$5/ thin films from the result of AES analysis. We changed the thickness of V$_2$O$\_$5/ about 20 to 150 $\AA$ and thickness of V about 10 to 20 $\AA$. As the result of this, TCR value of multi-layer VOx thin films was about -2%/k and the resistivity was ∼1Ωcm.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.5
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• pp.499-508
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• 2017

This paper uses optimization techniques to obtain bow hull form of a 66,000 DWT bulk carrier in calm water and in waves. Parametric modification functions of SAC and section shape of DLWL are used for hull form variation. Multi-objective functions are applied to minimize the wave-making resistance in calm water and added resistance in regular head wave of ${\lambda}/L=0.5$. WAVIS version 1.3 is used to obtain wave-making resistance. The modified Fujii and Takahashi's formula is applied to obtain the added resistance in short wave. The PSO algorithm is employed for the optimization technique. The resistance and motion characteristics in calm water and regular and irregular head waves of the three hull forms are compared. It has been shown that the optimal brings 13.2% reduction in the wave-making resistance and 13.8% reduction in the added resistance at ${\lambda}/L=0.5$; and the mean added resistance reduces by 9.5% at sea state 5.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.12
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• pp.1015-1020
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• 2012

Resistance of the front electrode is the highest proportion of the ingredients of the series resistance in crystalline silicon solar cell. While resistance of the front electrode is decreased with larger area, it induces the optical loss, causing the conversion efficiency drop. Therefore the front electrode with high aspect ratio increasing its height and decreasing is necessary for high-efficiency solar cell in considering shadowing loss and resistance of front electrode. In this paper, we used the screen printing method to form high aspect ratio electrode by multiple printing. Screen printing is the straightforward technology to establish the electrodes in silicon solar cell fabrication. The several printed front electrodes with Ag paste on silicon wafer showed the significantly increased height and slightly widen finger. As a result, the resistance of the front electrode was decreased with multiple printing even if it slightly increased the shadowing loss. We showed the improved electrical characteristics for c-Si solar cell with repeatedly printed front electrode by 0.5%. It lays a foundation for high efficiency solar cell with high aspect ratio electrode using screen printing.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.57-62
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• 2022

The plasma resistance of multi-component glasses containing La, Gd, Ti, Zn, Y, Zr, Nb, and Ta was analyzed in this study. The plasma etching was performed via inductively coupled plasma-reactive ion etching (ICP-RIE) using CF₄/O₂/Ar mixed gas. After the reaction, the glass with a low fluoride sublimation temperature and high content of P, Si, and Ti elements showed a high etching rate. On the other hand, the glass containing a high fluoride sublimation temperature component such as Ca, La, Gd, Y, and Zr exhibited high plasma resistance because the etch rate was lower than that of sapphire. Glass with low plasma resistance increased surface roughness after etching or nanoholes were formed on the surface, but glass with high plasma resistance showed little change in surface microstructure. Thus, the results of this study demonstrate the potential for the development of plasma-resistant glasses (PRGs) with other compositions besides alumino-silicate glasses, which are conventionally referred to as plasma-resistant glasses.

• Microbiology and Biotechnology Letters
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• v.51 no.4
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• pp.432-440
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• 2023

Irrational and injudicious use of antibiotics, easy availability of them as over-the-counter drugs in economically developing countries, and unavailability of regulatory policies governing antimicrobial use in agriculture, animals, and humans, has led to the development of multi-drug resistance (MDR) bacteria. The use of medicinal plants can be considered as an alternative, with a consequent impact on microbial resistance. We tested extracts of Piper longum fruits as new natural products as agents for reversing the resistance to antibiotics. Six crude extracts of P. longum fruits were utilized against a clinical isolate of multidrug-resistant Staphylococcus aureus.The antibiotic susceptibility testing disc method was used in the antibiotic resistance reversal analysis. Apart from cefoxitin and erythromycin, all other antibiotics used (lincosamides [clindamycin], quinolones [levofloxacin and ciprofloxacin], and aminoglycosides [amikacin and gentamicin]) were enhanced by P. longum extracts. The extracts that showed the greatest synergy with the antibiotics were EAPL (ethyl acetate [extract of] P. longum), n-BPL (n-butanol [extract of] P. longum), and MPL (methanolic [extract of] P. longum The results of this study suggest that P. longum extracts have the ability to increase the effectiveness of different classes of antibiotics and reverse their resistance. However, future studies are needed to elucidate the molecular mechanisms behind the synergy between antibiotic and phytocompound(s) and identify the active biomolecules of P. longum responsible for the synergy in S. aureus.

• Archives of Pharmacal Research
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• v.21 no.6
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• pp.734-737
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• 1998

The hexane fractions from methanolic extracts of Anetheum graveolens L. (Umbelliferae) and Acorus gramineus Soland. (Araceae) revealed potent inhibitory activities against the resistance of multi-drug resistant Staphylococcus aureus SA2 when combined with ampicillin (Am) or chloramphenicol (Cm). As active principles, carvone and the liquid mixture containing carvone from Anetheum graveolens L. and a liquid mixture mainly consisting of benzoic acid phenyl-methyl ester (benzyl benzoate) from Acorus gramineus Soland. were identified. They showed resistance inhibition at the level of 20-50${\mu}g$/ml when combined with 100 or ${\mu}g$/ml of Am or Cm, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.8
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• pp.664-671
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• 2006

We propose the correlation to predict the spreading thermal resistance on a plate with symmetrical four heat sources. The correlation transforms four heat sources to a single equivalent heat source and then the spreading thermal resistance can be obtained with the existing equation for a single heat source. When the four heat sources are mounted on a square base plate, the correlation is expressed as a function of the heat source size, the length of base plate, the plate thermal conductivity and the distance between heat sources. Compared to the results of three-dimensional numerical analysis, the spreading thermal resistance by the proposed correlation is in good agreement within 10 percent accuracy.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.108-109
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• 2014

The purpose of this study is to enhance durability of solidifying mat. solidifying mat excellent mechanical properties of geotextile. multi-layer coating system is applied to the mat and the chloride ions penetration resistance, chemical resistance, accelerated carbonation test were evaluated by testing the durability. Durability test results are as follows. chloride ions penetration resistance results are coated mat is approximately 70 % lower than plain. chemical resistance test results are coated mat no discoloration. accelerated carbonation test results are coated mat is approximately 90 % lower than the plain.