• International journal of steel structures
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• v.18 no.5
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• pp.1607-1616
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• 2018

Quantitatively modeling and propagating all sources of uncertainty stand at the core of seismic fragility assessment of structures. This paper investigates the effects of various sources of uncertainty on seismic responses and seismic fragility estimates of single-layer reticulated domes. Sensitivity analyses are performed to examine the sensitivity of typical seismic responses to uncertainties in structural modeling parameters, and the results suggest that the variability in structural damping, yielding strength, steel ultimate strain, dead load and snow load has significant effects on the seismic responses, and these five parameters should be taken as random variables in the seismic fragility assessment. Based on this, fragility estimates and fragility curves incorporating different levels of uncertainty are obtained on the basis of the results of incremental dynamic analyses on the corresponding set of 40 sample models generated by Latin Hypercube Sampling method. The comparisons of these fragility curves illustrate that, the inclusion of only ground motion uncertainty is inappropriate and inadequate, and the appropriate way is incorporating the variability in the five identified structural modeling parameters as well into the seismic fragility assessment of single-layer reticulated domes.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.107-107
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• 2017

3D bioprinting is a technology to produce complex tissue constructs through printing living cells with hydrogel in a layer-by-layer process. To produce more stable 3D cell-laden structures, various materials have been developed such as alginate, fibrin and gelatin. However, most of these hydrogels are chemically bound using crosslinkers which can cause some problems in cytotoxicity and cell viability. On the other hand, thermosensitive hydrogels are physically cross-linked by non-covalent interaction without crosslinker, facilitating stable cytotoxicity and cell viability. The examples of currently reported thermosensitive hydrogels are poly(ethylene glycol)/poly(propylene glycol)/poly(ethylene glycol) (PEG-PPG-PEG) and poly(ethylene glycol)/poly(lactic acid-co-glycolic acid) (PEG/PLGA). Chitosan, which have been widely used in tissue engineering due to its biocompatibility and osteoconductivity, can be used as thermosensitive hydrogels. However, despite the many advantages, chitosan hydrogel has not yet been used as a bioink. The purpose of this study was to develop a bioink by chitosan hydrogel for 3D bioprinting and to evaluate the suitability and potential ability of the developed chitosan hydrogel as a bioink. To prepare the chitosan hydrogel solution, ${\beta}-glycerolphosphate$ solution was added to the chitosan solution at the final pH ranged from 6.9 to 7.1. Gelation time decreased exponentially with increasing temperature. Scanning electron microscopy (SEM) image showed that chitosan hydrogel had irregular porous structure. From the water soluble tetrazolium salt (WST) and live and dead assay data, it was proven that there was no significant cytotoxicity and that cells were well dispersed. The chitosan hydrogel was well printed under temperature-controlled condition, and cells were well laden inside gel. The cytotoxicity of laden cells was evaluated by live and dead assay. In conclusion, chitosan bioink can be a candidate for 3D bioprinting.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.97-103
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• 2001

Polycrystalline thin films of La$_{2}$3/Sr$_{1}$3/MnO$_3$(LSMO) were prepared by water-based sol-gel processing on thermally oxidized Si(100) substrate. The thickness dependence of the low-field tunnel-type magnetoresistance properties at room temperature was studied. Tunnel-type magnetoresistance at low-field is found to be strongly dependent on film thickness. Maximum value of tunnel-type magnetoresistance of LSMO thin films was appeared at the film thickness of ~1500 $\AA$. This behavior can be explained in terms of dead layer between LSMO thin film and Si(100) substrate and thermal lattice strain effect in the LSMO thin films.

• Journal of Environmental Science International
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• v.23 no.1
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• pp.39-46
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• 2014

This study surveyed Abies koreana to identify the correlation between its vegetation structure according to its slope direction and seedling establishment in a bid to build basic research data on the changes and conservation of the A. koreana in Hallasan Mountain. The findings of its vegetation structure revealed that in both areas, Importance value was given to the A. koreana for its tree layer, the Taxus cuspidata for its shrub layer, and the Sasa quelpaertensis for its herb layer. However, in the Youngsil area with the tree layer, high importance was given to deciduous broad-leaved trees such as Prunus maximowiczii, Quercus mongolica, and the young species of the A. koreana in the shrub layer that can maintain the A. koreana forest's greater importance in the Jindallebat than in the Youngsil. Thus, the A. koreana forest in the Jindallebat is believed to lastlonger. The findings of correlation between the quantity of seedlings and their location by area revealed that in each tiny quadrat, the A. koreana seedling averaged 5.3 in the Youngsil and 2.9 in the Jindallebat. Both areas were all found to have a positive correlation in terms of rock exposure ratio and dead tree ratio as well as a negative correlation with regard to the cover degree of S. quelpaertensis, the canopy gap, the total vegetation, and the herb layer. It was found that the cover degree of the herb layer in the Youngsil and the S. quelpaertensis in the Jindallebat had the largest impact on the A. koreana seedlings.

• Ocean and Polar Research
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• v.29 no.1
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• pp.81-86
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• 2007

Abandoned fishing nets served Little Tern(Sterna albifrons) chicks as cover on a sandy island on Ganwol Lake, Hongsung-gun, Chungcheongnam-do, Korea. Chicks were incidently caught in $2.5cm{\times}2.5cm$ mesh sized nets and died of dehydration and exhaustion. Three adults died when they were caught by abandoned fishing net during parental care period in $2.5cm{\times}2.5cm$ mesh sized nets. Whereas $0.7cm{\times}0.7cm$ mesh sized nets did not affect the chicks' or adults' survival. Overlapped nets with several layers were more dangerous for chicks than were spread nets with a single layer. Dead chicks and adults were found to have been entangled by wing and neck. In this study, wing and nape(head+bill) of dead chicks were longer than those of live chicks. To improve the survival rate of Little Tern chicks at Ganwol Lake, abandoned fishing nets must be removed before the breeding season.

• Journal of Magnetics
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• v.6 no.3
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• pp.80-82
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• 2001

We have investigated magnetism of $Fe_2 /Ir_4$(001) superlattice in terms of a first-principles calculation by using an all-electron full-potential linearized augmented plane-wave (FLAPW) method within the generalized gradient approximation (GGA). We considered two magnetic states, the ferromagnetic (FM) and antiferromagnetic (AFM) coupled states between the Fe layers. It was found that the FM state was energetically more stable than the AFM one by 0.166 eV. Calculated magnetic moments of the Fe layers were, in absolute values, 2.45$\mu_B$ and 2.30 $\mu_B$for the FM and AFM states, respectively. We also found that the Ir layers had very small magnetic moments less than 0.1 $\mu_B$ for both magnetic states. In all the magnetic states, the subinterface Ir layers were coupled antiferromagnetically to the interface Ir layers, while the interface Ir layers were always coupled frerromagnetically to the interface Fe layers. These results contradicted to recent experimental reports of magnetically "dead"Fe layers in Fe/Ir superlattices for which the Fe layer thickness was less than two atomic layers. We attributed that the experimentally observed "dead"Fe layers were due to possible interdiffusion between Ir and Fe layers.en Ir and Fe layers.

• Journal of Biosystems Engineering
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• v.32 no.3
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• pp.173-178
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• 2007

This research was conducted to develop and analyze a wireless monitoring system for judging if sick or dead layers (SDL) exist in multi-tier layers battery (MLB) by machine vision, and to evaluate the performance between a wired monitoring system and it. This study used the AP (Access Point), the RS-285 to RS-232 converter, RS-232 to Ethernet converter, PICBASIC board and upgraded lump image processing method to change wired monitoring system into wireless monitoring system. The system was tested at a pilot farm and farm layer house. Results showed that monitoring judgement success rate at a pilot farm on normal cage (without SDL) was 82.3% and that on abnormal cage (with SDL) was 87.5%, respectively. And communication performance test results showed at farm layer house was $700{\sim}900$ kbps while equipments operated. There were dropped slightly than performance of wired monitoring system, however, the quantity was too small to make a significant difference of performance of the controling system developed for wireless communication.

• Korean Journal of Environment and Ecology
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• v.29 no.1
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• pp.81-87
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• 2015

This study was carried out in the peatland for estimating the paleoenvironment based on the analysis from its fossils plant and radiocarbon at the Hwayang-ri, Hyeondeok-myeon, Pyeongtaek-city, South Korea. Variety of fossil was collected from the peatland which could discriminated with naked eye and sorted into seeds, leaves, stems from four-stage of standard sieve. During analysis for the large plant fossil within the peatland, the dead plants were largely divided into 3 fossil zones according to its peatland. In the fossil zone III (the oldest layer; 6,970~6,070 yr $C^{14}$ B.P.), the observation of leaves of hydrophyte such as Trapa sp. and stems of Alnus japonica which appeared in wetland means that the environment was influenced by the climate changes such as rainfall increasing and sea level rise. In the fossil zone II (the middle layer; 6,070~5,800 yr C14 B.P.), the occurrence of Gramineae, Cyperaceae and Fagaceae indicate that the environmental condition might be more or less dry by decreasing rainfall and drop in sea level. The fossil zone I (the recent layer; 5,800~4,540 yr $C^{14}$ B.P.) where lots of herbaceous plants, increasing of Fagaceae, decreasing of A. japonica. and distribution of Pinaceae were showed, was inferred to be repeated both dry and wet environment due to human disturbance.

• Journal of Korean Society of Transportation
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• v.19 no.6
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• pp.19-31
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• 2001

In this paper, 3 layered architecture model and related design guidelines are proposed, which have been actually applied in our national ITS-Architecture design. The domain architecture as the 1st layer is to structure all ITS related domains for maximizing the co-operability in national level. The logical architecture as the 2nd layer is to structure all ITS related application-systems for minimizing duplications, conflicts and dead-zones in service level and maximizing the co-operability in application-system level. The physical architecture as the 3rd layer is to structure all IT(Information Technology) related physical resources for maximizing.

• Journal of Magnetics
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• v.9 no.3
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• pp.79-82
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• 2004

The structure and magnetic properties of Fe-Ni-N/Cu multilayered films, prepared by the DC magnetron sputter, as a function of different thicknesses of Fe-Ni-N ($t_{FeNiN}$) and Cu ($t_Cu$) layers have been studied by the methods of x-ray diffraction and measurement of magnetic moment. It has been found that the enhancement of (200) orientation in Fe-Ni-N layers is observed at the ratio of layer thickness with about $t_{FeNiN}/t_{Cu}$ $\underline{\simeq}$ 3.75. The reduction of magnetization due to the formation of interdiffusion near the interface is explained by means of the dead layer model. The temperature dependence of magnetization exhibits the feature of Blochs $T^{\frac{2}{3}}$ law. The layer thickness dependence of Curie temperature has been discussed by critical temperature theory of Heisenberg model.