• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.879-884
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• 2001

In this paper, the structural and dielectric properties of (Sr$_{l-x}$Ca$_{x}$)TiO$_3$ (0$\leq$x$\leq$0.2) -based grain boundary layer ceramics were investigated by XRD, SEM and HP4194A. The ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were 1420~152$0^{\circ}C$ and 4 hours, respectively. The average grain size and the lattice constant were decreased with increasing content of Ca. The average grain size was increased with increase of sintering temperature. The relative density of all specimens was 96~98%. The 2nd Phase formed by the thermal diffusion of CuO from the surface leads to very excellent dielectric properties, that is, $\varepsilon$$_{r}$>50000, tan $\delta$<0.05, $\Delta$C<$\pm$10%. The appropriate Ca content was under 15 ㏖%.s under 15 ㏖%.%.

• Journal of Animal Environmental Science
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• v.7 no.2
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• pp.127-136
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• 2001

This experiment was carried out to investigate the effect of supplementing phosphorus to Korean cow manure on the growth and cast production of earthworm(Eisenia Foetida), and to estimate the optimal phosphorus level for the growth and cast production of earthworm and ratios of available phosphorus and calcium content of cast in optimal phosphorus levels. Phosphorus supplementing ratios to Korean native cow were 0, 1%, 2%, 4% and 8A%, respectively. The volume of raising box was 3375cm$^3$(15$\times$15$\times$15cm), and 500g of cow manure filled up to 10cm layer. Raising density was 90㎤ per worm during the experimental period(60 days). The maximum fresh weight and cast production of earthworm were obtained at 2~4% and 1% levels of phosphorus supplementation to Korea native cow manure. The total phosphorus and available phosphorus contents of earthworm tissues were not significant among in all treatments. There was a positive significantly differences between total phosphorus and available phosphorus of cast and residual matters. Available phosphorus content of cast were ranged from 9.3mg/g to 17.3mg/g at 1~4% levels of phosphorus supplementation. Ratios of available phosphorus and calcium contents of cast were 1.94~3.15:1 and 0.87~1.33:1 at 2~4% and 0~1% levels of phosphorus supplementation.

• Korean Journal of Metals and Materials
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• v.46 no.12
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• pp.817-822
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• 2008

Metal matrix composite (MMC) materials having low electrical contact resistance based on 316L stainless steel (STS) matrix alloy with $ZrB_2$ particles were fabricated for PEMFC (Polymer Electrolyte Membrane Fuel Cell) separator by powder metallurgy (PM). The effects of the boride particle addition into the matrix alloy on microstructure, surface morphology, and interfacial contact resistance (ICR) between the samples and gas diffusion layer (GDL) were investigated. Both conventional and PM 316L STS samples showed high ICR due to the existence of non-conductive passive film on the alloy surface. The addition of the boride particles, however, remarkably reduced ICR of the samples. SEM observation revealed that the boride particles were protruded out of the matrix surface and particle density existing on the surface increased with increasing the boride content, causing increase of the total contact area between the conductive particles and GDL. ICR of the samples also decreased with increasing the boride content resulted from the increased contact area.

• Journal of Forest and Environmental Science
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• v.35 no.1
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• pp.31-40
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• 2019

Daphne pseudomezereum var. koreana is an endangered deciduous shrub distributed in mountain areas that is vulnerable to climate change. The purpose of this study was to provide foundational data on the physical characteristics, soil environment, and vegetation structure of habitats of Daphne pseudomezereum var. koreana habitat in Korea in order to help with management decisions on ecosystem restoration. Rock exposure was 15 to 35%, with an average of 24%. The native habitat of D. pseudomezereum included 129 taxa consisting of 46 families and 95 genera. Two-way cluster analysis divided the habitat into three plant communities: Community I (dominaterd by Tilia amurensis and Quercus mongolica), Community II (dominaterd by Fraxinus rhynchophylla and Acer pseudosieboldianum), and Community III (dominaterd by Ulmus davidiana var. japonica). The diversity indices for Communities I, II, and III were 1.124, 1.047 and 0.932, respectively. The soils were loam or clay loam. Soil pH, organic matter content, and available phosphoric acid were 5.40, 14.38%, and 31.08 ppm, respectively. Ordination analysis resulted that most significant factors influencing D. pseudomezereum distribution were magnesium content of soil, shrub layer, and altitude.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.10
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• pp.3642-3667
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• 2021

Texture synthesis technology has the advantages of repairing texture and structure at the same time. However, during the filling process, the size of the patch is fixed, and the content of the filling is not fully considered. In order to be able to adaptively change the patch size, we used the exemplar-based inpainting technique as the test algorithm, considering the image structure and texture, calculated the image structure patch size and texture patch size, and comprehensively determined the image patch size. This can adaptively change the patch size according to the filling content. In addition, we use multi-layer images to calculate the priority, so that the order of image repair was more stable. The proposed repair algorithm is compared with other image repair algorithms. The experimental results showed that the proposed adaptive image repair algorithm can better repair the texture and structure of the image, which proved the effectiveness of the proposed algorithm.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.2
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• pp.1-10
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• 2021

Lithium-ion batteries with high energy density, long cycle life and other advantages, have been widely used to energy storage systems(ESS). But as ESS fires frequently occur, the safety concern has become the main obstacle that hinders the large-scale applications of lithium-ion batteries. Especially, thermal runaway is the key scientific problem in battery safety research. Therefore, in this study, we performed a numerical analysis on the thermal runaway phenomenon of NCM111, NCM523 and NCM622 batteries using a two-dimensional analysis model. The results show that the two-dimensional simulation results are generally matched with three-dimensional simulation. Also, In the case of NCM111 with a low Ni content in the temperature range used in this study, thermal runaway phenomenon does occurred very slowly, but as the Ni content is increased, the thermal runaway phenomenon occurs rapidly and the thermal stability tends to be decreased. And, in NCM523 and NCM622 batteries, chain reactions occur almost simultaneously, but in the case of NCM111 battery, it is found that after the SEI(Solid Electrolyte Interface) layer decomposition reaction, the cathode-electrolyte reaction is appeared sequentially. After that, the anodic decomposition reaction is increased and leads to the thermal runaway reaction.

• Structural Engineering and Mechanics
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• v.82 no.2
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• pp.163-172
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• 2022

Zinc-rich epoxy (ZRE) is used to overcome corrosion problems in reinforced concrete (RC) beams and coat steel rebars to protect them from humidity and chlorides. An extra coating layer of Sikadur-31 epoxy (SDE) is utilised to increase bond strength because the use of ZRE reduces the bond strength between concrete and steel rebars. However, the low melting point of SDE indicates that concrete specimens are vulnerable to fire. An experimental investigation on flexural performance of RC beams incorporating ZRE-SDE coating of steel rebars that were destroyed by fire is performed in this study. Twenty beams of five concrete mixes with different cementitious contents were tested to compare fire exposure for coated and uncoated rebars of the same beams at room temperature and determine the optimal cementitious content. Scanning electron microscopy (SEM) was also applied to investigate characteristics of fired mixture samples. Results showed that the use of SDE-ZRE at room temperature improves flexural strengths of the five mixes compared with uncoated rebars with percentages ranging from 8.5% to 12.3%. All beams with SDE-ZRE lost approximately 50% of their flexural strength due to firing. Moreover, the mix incorporating SF (silica fume) of 15% and cement content of 400 kg/m³ introduces optimum behaviour compared with other mixes. All results were supported and verified by the SEM analysis and compressive strength of cubic specimens of the same mixes.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.06a
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• pp.73-73
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• 2001

Boron-containing materials have several excellent properties, such as superlnardness, insulation and non-Rinear optical property. Recently, oxynitride compounds, such as Si(ON), Ti(ON), became the promising materials applied in diffusion barrier layer and solar cell. With the expectation of obtaining the hybrid property, we have firstly grown the BON thin film by radio frequency (R.F.) plasma enhanced metalorganic chemical vapm deposition (PEMOCVD) with 100 kHz frequency and trimethyl borate precursor. The plasma source gases used in this study were Ar and $H_2$, and two kinds of nhmgen source gases, $N_2$ and <$NH_3$, were also employed. The as-grown films were characterized by XPS, IR, SEM and Knoop microlhardness tester. The relationship between the films hardness and the growth rate indicated that the hardness of the film was dependent on several factors such as nitrogen source gas, substrate temperature and film thickness due to the variation of the composition and the structure of the film. Both nitrogen and carbon content could raise the film hardness, on which nitrogen content did stronger effect than carbon. The smooth morphology and continuous structure was benefit of obtaining high hardness. The maximum hardness of BON film was about 10 GPa.

• Journal of the Korean Wood Science and Technology
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• v.51 no.2
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• pp.81-97
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• 2023

The aim of this study were to evaluate tannin resorcinol formaldehyde (TRF) for the preparation of cross-laminated timbers (CLTs) made from fast-growing tree species and to analyze the physical and mechanical properties of CLTs. TRF copolymer resin was prepared by using the bark extracts of Swietenia mahagoni (L.) Jacq. It was observed that the TRF adhesive possessed less solid content (23.59%), high viscosity (11.35 poise), and high pH values (10.0) compared to the standard phenol resorcinol formaldehyde. The TRF adhesive was applied to produce CLTs with the addition of 15% tapioca and flour as an extender. The six-layered CLTs were produced from sengon (Falcataria moluccana Miq.), jabon [Anthocephalus cadamba (Roxb) Miq.], coconut (Cocos nucifera L.), and the combination of coconut-jabon and coconut-sengon wood. The analysis of variance revealed that the layer composition of CLT significantly affected the physical and mechanical properties of the beam. While the modulus of rupture met the standard, the moisture content and modulus of elasticity values did not fulfill JAS 1152-2007. All of the CLTs produced in this study demonstrated low formaldehyde emission, ranging from 0.001 mg/L to 0.003 mg/L, thereby satisfying the JAS 1152 for structural glue laminated timber.

• International Journal of Advanced Culture Technology
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• v.11 no.2
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• pp.249-255
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• 2023

This study aims to empirically confirm the effect and impact of community care design research centered on domestic space and environment on health promotion, diagnosis treatment, disease management, rehabilitation, and mitigation through the year of publication and perspective. To this end, based on 1,227 space and environment design studies from 2,144 community care design research data conducted for about 20 years from 2002 to 2022, when care services began in earnest through the long-term care system for the elderly, SPSS 26.0 was used to create a 'Multi-layer Perceptron' artificial neural network structure model was predicted and neural network analysis was performed. Research Results First, as a result of checking studies in each field of health care by year, there is a significant difference with the number of studies related to health promotion being the highest. Second, the five perspectives are region, time, dimension, function, and content perspective. As a result of inputting these variables as independent variables and analyzing their importance in the artificial neural network, the function perspective had the most influence, followed by the region > content > dimension > time perspective.