• Elastomers and Composites
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• v.38 no.4
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• pp.342-353
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• 2003

This work is about the development of jet-fuel resistant PVC sealant using a polyester plasticizer. PVC copolymer was compounded with adipic acid glycol(Songcizer P-3000) or DOP plasticizers. Fuel-immersed and non-immersed penetration, solubility, flow, and elongation by tensile adhesion of PVC compounds were measured. Penetration increase by fuel immersion and solubility of PVC compounds with adipic acid glycol polyester plasticizer were smaller than those of PVC compounds with DOP plasticizer. Elongation by tensile adhesion test of PVC compound containing 500 phr of Songcizer P-3000 decreased proportionally to the content of DCDP (dicyclopentadiene) base petroleum resin adhesion promoter. Calcium carbonate($CaCO_3$) filler inhibited the diffusion of fuel in all the PVC compounds and decreased the solubility of PVC compounds containing Songcizer P-3000.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.37-44
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• 2016

This study is concerned with the numerical investigation of dynamic characteristics of 2.5MW-class wind turbine gearbox in which the misalignment improvement of plenary gear shafts by the flexible pins and the dynamic impact response are analyzed by the finite element method. The tooth contact between gears is modelled using the line element having the equivalent tooth stiffness and the contact ratio to accurately and effectively reflect the load transmission in the internal complex gear system. The equivalent tooth stiffness is calculated by utilizing the tooth deformation analysis and the impulse torque is applied to the input shaft for the dynamics response characteristic analysis. Through the numerical experiments, the equivalent tooth stiffness model was validated and the misalignment improvement of planetary gear shafts was confirmed from the comparison with the cases of fixed shafts at one and both ends.

• Fire Science and Engineering
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• v.25 no.6
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• pp.146-155
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• 2011

In the study, test was carried out to compare the flame retardant performance for the specimen of MDF wood to which field flame retardant treatment (post processing flame retardant) is applied, which is coated with flame retardant film of 5 companies, locally distributed, and MDF wood (nontreated, flame retardant film non-coated) to which aqueous or oil-based fire-retardant paint is applied. As a result of combustion test of MDF wood which was coated with flame retardant film of 5 companies, 2 products showed suitable values in 4 criteria, but other 3 products showed 10~40 % disqualification rate. In regard of characteristics of fire-retardant paint, oil-based fire-retardant paint is better than aqueous fire-retardant paint in flame retardant performance criteria, but MDF wood to which oilbase fire-retardant paint was applied was shown to have higher toxicity index grade than MDF wood to which aqueous fire-retardant paint was applied relatively.

• Industry Promotion Research
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• v.9 no.2
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• pp.45-58
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• 2024

This study modelled the social network structure characteristics between Innopolis Start-ups located in Daejeon and Innopolis Start-ups' customers scattered across the country as a tendency of regional clustering among homogeneous technologies, and the observed values were included within the 95% confidence interval of the ERGM(Exponential Random Graph Model) analysis model. If both the research institute and the customer company are located in Yuseong-gu, Daejeon, the probability of being connected is about 13 times higher than if they are located in other administrative districts, and there is a strong tendency of connection between firms with the same technology with a negative value of assortment and homogeneity (0.1904), especially among the six technology sectors, with a P value of 0.035. There was a negative value (-0.0035) among firms not located in Yuseong-gu, with less clustering tendency. This confirms that Yuseong-gu, Daejeon, where the Daedeok Innopolis is located, is forming the centre of an innovation cluster.

• Food Science and Preservation
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• v.19 no.1
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• pp.95-103
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• 2012

The objective of this study was to develop models for the predict of the milk properties (fat, protein, SNF, lactose, MUN) of unhomogenized milk using the visible and near-infrared (NIR) spectroscopic technique. A total of 180 milk samples were collected from dairy farms. To determine optimal measurement temperature, the temperatures of the milk samples were kept at three levels ($5^{\circ}C$, $20^{\circ}C$, and $40^{\circ}C$). A spectrophotometer was used to measure the reflectance spectra of the milk samples. Multilinear-regression (MLR) models with stepwise method were developed for the selection of the optimal wavelength. The preprocessing methods were used to minimize the spectroscopic noise, and the partial-least-square (PLS) models were developed to prediction of the milk properties of the unhomogenized milk. The PLS results showed that there was a good correlation between the predicted and measured milk properties of the samples at $40^{\circ}C$ and at 400~2,500 nm. The optimal-wavelength range of fat and protein were 1,600~1,800 nm, and normalization improved the prediction performance. The SNF and lactose were optimized at 1,600~1,900 nm, and the MUN at 600~800 nm. The best preprocessing method for SNF, lactose, and MUN turned out to be smoothing, MSC, and second derivative. The Correlation coefficients between the predicted and measured fat, protein, SNF, lactose, and MUN were 0.98, 0.90, 0.82, 0.75, and 0.61, respectively. The study results indicate that the models can be used to assess milk quality.

• Journal of Dairy Science and Biotechnology
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• v.33 no.3
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• pp.209-214
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• 2015

This study was carried out to investigate the effects of different milking systems (AMS, automatic milking system and CMS, conventional milking system) and of supplemental fat feeding on milk composition and milk fat characteristics. The composition, MFG (milk fat globule) size, fatty acids (FAs), and free fatty acids (FFAs) of the milk from 4 AMS and 4 CMS dairy farms were analyzed on the basis of the milking system and feeding of protected fat. The milking system did not affect milk composition, MFG size, and milk FAs, but FFA content of AMS milk were significantly higher than that of CMS milk. Feeding of protected fat resulted in the production of milk much higher in LCFAs (long chain FAs); however, the milk composition was not affected by fat supplementation. Cows administered protected fat supplements produced milk containing MFGs with a large average diameter.

• Korean Journal of Organic Agriculture
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• v.24 no.3
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• pp.453-463
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• 2016

This study was undertaken to investigate the effects of dicarboxylic acid supplementation, as replacement antibiotics, of on in vitro ruminal parameters and milk yield and milk composition in lactating cows. in vitro treatments were 1) Con (4 g of basal diet), 2) CM (4 g of basal diet + 0.05 ml of monensin), 3) CR (4 g of basal diet + 0.1 ml of dicarboxylic acid) and in vivo treatments were 1) Con (25 kg of basal diet/head/day), and 2) CR (25 kg of basal diet + 5 g of dicarboxylic acid/head/day), respectively. A total 10 lactating dairy cows ($649{\pm}19kg$ average body weight, $99{\pm}65$ average milking days) were divided in to two groups according to mean milk yield and number of days of postpartum. The cows fed a basal diet during adaptation (2 wk) and experimental diets during the treatment periods (4 wk). In the first in vitro experiment, there were no statistical differences between treatments in pH, gas production, and ammonia-N and lactic acid concentration during incubation. However, dry matter digestibility was significantly higher in CR treatment compared to control or CM treatment (P<0.05). Total VFA was tended to higher in CR treatment than those of control and CM treatment (P>0.05). In the second experiment, milk yield was significantly higher in treatment (40.39 kg) compared to control (35.19 kg), (P<0.05). Milk composition and MUN were not changed by dietary supplementing dicarboxylic acid. Therefore the present results reporting that supplementation of dicarboxylic acid might enhance the stabilization of ruminal fermentation and increase the milk yield of lactating cows.

• The Journal of Sustainable Design and Educational Environment Research
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• v.15 no.2
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• pp.13-22
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• 2016

The purpose of this study is to provide a basis for determining when a school established long term school plans accepted by analyzing the trend of increase or decrease elementary school students 30 years to target of Daejeon Metropolitan City. Most were analyzed for land development area of Yuseong-Gu, and most of the old downtown area of Dong-Gu for this purpose. Results of this study are as follows: First, the results of this research to analyze the number of students increase or decrease trend forecasting model specific case in residential development projects in the district are Model8 4 schools (11.8%) in Yuseong-Gu were compared higher than one schools (4.3%) in the Dong-Gu. This suggests the need for a cautious approach in the planning of schools accommodated in a large housing development district. Second, large-scale land development trend analysis results Students sensitized Yuseong-Gu business district is followed by a new school in 11 schools (29.7%), Old town in Dong-Gu, which is contrary 13 schools (56.5%) were in a downturn.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.1
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• pp.55-68
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• 1999

A muti-lamellar emulsion containing a pseudoceramide, N-Ethanol-2-myristyl/ palmityl-3-oxostearmide/arachidamide(PC-9) has been prepared and its efficacy evaluation has been investigated. In order to prepare a muti-lamellar emulsion, first, the gram ratios of PC-9, fatty acid and cholesterol on the phase diagram to be capable of forming their lamellar liquid crystal structures were determined and secondly, the multi-lamellar emulsion was preprared using glyceryl monostearate and polyoxyethylene glyceryl monosteartate as emulsifers together with above mentioned pseudo-stratum corneum lipid components. Besides natural oils such as olive oil had a tendency to build up the multi-lamellar emulsion. And according as the amount of oil increased in the emulsion, it was observed that the optical anisotropy of “Maltese Cross” which was a typical configuration of multi-lamella mesophase texture diminished. In the dried state of the multi-lamella emulsion, it was examined to transform its emulsion phase into a lamella liquid crystal one. And finally, when the emulsion was applied into a human skin, it was investigated that it had effectiveness in reducing transepidermal water loss (TEWL) of the skin.

• Resources Recycling
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• v.31 no.2
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• pp.63-69
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• 2022

In this study, mechanical grinding using a planetary ball mill was performed under various conditions to evaluate its effect on the crystal structure of vanadium titanium magnetite (VTM) ore from the Kwain Mine in South Korea. The crystal structure of the activated product was also evaluated. Magnetite and ilmenite were identified as the main types of VTM ore used in the Kwain Mine, and the main types of gangue minerals were iron-based silicate minerals. According to the mechanical activation results, the crystallinity and crystal size decreased as the size of the grinding media (balls) decreased, and the amorphization of the sample/ball filling was significant as the amount of the sample was reduced. In addition, as the grinding speed and time increased, the crystal structure significantly changed, proving that these two parameters had a greater effect on the crystal structure than the ball size and sample/ball filling ratio.