• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.129-138
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• 2004

In this study we determine a dynamic analysis of the existing two-span prestressed concrete box girder bridge subjected to moving vehicle loads using the experimental measurements. The moving loads applied in this paper are classified as general travelling, suddenly brake, continuous travelling, reversely travelling and reversely travelling impact loads for increasing velocities. For each travelling load, we search dynamic behaviors and characteristic in various measuring point of box girder section. In addition, the three-dimensional numerical results analyzed by the developed finite element program using flat shell element with six degrees of freedom per a node are compared with the measured experimental data. Dynamic behaviors caused impact loads by suddenly braking, reversely travelling, are bigger than by general travelling in box girder. Three-dimensional numerical results are better than one-dimensional results.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.534-540
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• 2014

The analysis of the change in the herbal tea composition according to the difference in processing conditions result. Was slightly reduced crude is treated ash puffing process was relatively increased, moisture, crude protein, the solid elution rate than the roasting process. Benzopyrene content was significantly reduced to 0.18 ppb from 0.35 ppb. Generation of food $B({\alpha})P$ is mainly include the thermal decomposition of food cooking, when the processing which is a main component of food carbohydrate, protein, fat reason despite severe heat treatment as a whole is to be detected even though the $B({\alpha})P$ in this way is considered to be. Generally the taste, aroma and color did not show a big difference but tasted quite stuffy and the strong sour taste reduced its preference.

• Journal of agriculture & life science
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• v.43 no.6
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• pp.111-115
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• 2009

This study was conducted to develop the ultrasonic dryer because present drying methods (heat convection, microwave, vacuum, etc.) could not improve the drying consumption energy, decrease of quality and drying ratio by physical limitation. The drying tests were conducted with four levels (No. 1 only non-heated air, No. 2 only ultrasonic, No. 3 only heated air and No. 4 ultrasonic with heated air) and measuring weight of samples after drying carrot and ginseng slices for 30 minutes. The result of test is that the drying ratio was highest in the level of No. 4 ultrasonic with heated air. The sliced carrot's drying ratio was 22.4% (w.b.)/h and sliced ginseng's drying ratio was 3.8% (w.b.)/h. The discoloration and twist of samples was appeared on using only heated air like No. 3.

• Elastomers and Composites
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• v.43 no.1
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• pp.8-17
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• 2008

Styrene-butadiene rubber(SBR) has good abrasion resistance, miscibility, and anti-vibration property. however, it is easily damaged by ozone and swelled by hydrocarbon fluids because of unsaturation part in main chain, that causes loss of visco-elasticity and reduction of product's life cycle. Therefore, object of this study is to cope with this problem. SBR is blended with various proportion of ethylene-propylene-diene terpolymer(EPDM), which has excellent ozone and oxygen resistance, to improve physical properties and ozone resistance, and diverse analytical techniques are used to measure morphology, glass transition temperature$(T_g)$, ozone-resistance, degradation temperature, static spring constant, hardness for considering a suitability for anti-vibration industrial product. We found that the blend consisting of SBR 70% and EPDM 30% showed no crack after ozone test and good miscibility between SBR and EPDM from this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.20-27
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• 2019

Compared to the development and manufacturing technology of electronic goods, the development of waste glass recycling technology is relatively insufficient, leading to the acceleration of waste of resources and environmental pollution. Although waste glass recycling technology is being actively developed overseas, waste glass recycling technology is insufficient in Korea, leading to the illegal dumping or burial of waste glass. Waste glass has been confirmed to have pozzolan reaction potential when having hydration reaction with cement. Waste glass is also reported to be effective in reducing bleeding and inhibiting the development of hydration heat by improving the physical properties of concrete and the rheology properties of fresh concrete. Therefore, this paper analyzed the strength characteristics and the effect of alkalic-silica reaction on the expansion of shielding concrete that used waste glass as fine aggregate. Where, suitable admixture materials were used as a measure to suppress the expansion.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.239-249
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• 1999

In this study, experimental work has been carried out to investigate the effect of lateral soil movement on passive piles. This paper consists mainly of two parts: the first, performance of a series of laboratory experiments on a single pile and one-row pile groups, and the second, comparison between the measured and the predicted results. In the laboratory experiments, a quadrilateral soil movement profile was imposed on model piles embedded in both sandy soils and weathered soils. The maximum bending moment and pile deflection induced in passive piles were found to be highly dependent on pile stiffness, pile spacing, relative densities and pile head fixity condition. It was shown that the group effect might either increase or decrease the maximum bending moment and pile deflection, depending on the aforementioned influence factors. Based on the results obtained, a spacing-to-diameter ratio of 7.0 seems to be large enough to eliminate the group effect, and a pile in such a case behaves essentially the same as a single pile.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.161-167
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• 2011

In case that the maximum temperature of any surface readily accessible during transport of a spent nuclear fuel (SNF) transport cask exceeds $85^{\circ}C$ in the absence of insolation under the ambient temperature of $38^{\circ}C$, personnel barriers or transport hood shall be used to prevent people from casual contact with the transport cask surface. Usually the air temperature within the hood and the hood surface temperature are calculated and further utilized as boundary conditions(free stream temperature and external radiation temperature) for thermal evaluation under normal conditions of transport. In this study, these temperatures are derived using the analytical method based on the heat transfer mechanism around the transport cask under transport hood assuming the thermal equilibrium. By comparing the analytical solutions with the results from the detailed calculations with CFD-computer-code FLUENT 12.1 it is verified that the analytical method is still efficient tool to estimate the temperatures and these temperatures can be further used as boundary conditions for thermal evaluation under normal conditions of transport.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.11
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• pp.527-536
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• 2017

With the recent development of smart grid industry, the necessity for efficient EMS(Energy Management System) has been increased. In particular, in order to reduce electric load and energy cost, sophisticated electric load forecasting and efficient smart grid operation strategy are required. In this paper, for more accurate electric load forecasting, we extend the data collected at demand time into high time resolution and construct an artificial neural network-based forecasting model appropriate for the high time resolution data. Furthermore, to improve the accuracy of electric load forecasting, time series data of sequence form are transformed into continuous data of two-dimensional space to solve that problem that machine learning methods cannot reflect the periodicity of time series data. In addition, to consider external factors such as temperature and humidity in accordance with the time resolution, we estimate their value at the time resolution using linear interpolation method. Finally, we apply the PCA(Principal Component Analysis) algorithm to the feature vector composed of external factors to remove data which have little correlation with the power data. Finally, we perform the evaluation of our model through 5-fold cross-validation. The results show that forecasting based on higher time resolution improve the accuracy and the best error rate of 3.71% was achieved at the 3-min resolution.

• Polymer(Korea)
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• v.37 no.5
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• pp.557-562
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• 2013

The thermal expansion and mechanical properties of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardeners were studied by a comparative method with an amine-adduct type hardener. Thermal expansion and dynamic mechanical properties were measured by thermo mechanical analysis (TMA) and dynamic mechanical ananlysis (DMA), respectively. The $T_g$ and the coefficient of thermal expansion (CTE) of epoxy/amine-adduct type hardener system were $82.6^{\circ}C$ and 71.2 $ppm/^{\circ}C$, respectively. As the number of -SH functional group of mercaptan hardener increased, the $T_g$ rapidly decreased and gradually increased up to ca. $80^{\circ}C$ and the CTE under the $T_g$ rapidly increased to ca. 200 $ppm/^{\circ}C$ from 80 $ppm/^{\circ}C$ and decreased to ca. 100 $ppm/^{\circ}C$. The crosslinking density of epoxy with amine-adduct type hardener was ca.1.5 $mol/cm^3$, while that of epoxy with mercaptan hardeners increased from 1.0 to 1.7 $mol/cm^3$, as the number of -SH functional group increased. The storage modulus can increase up to 2700MPa at $30^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.3
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• pp.243-254
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• 2014

It is essential to predict the coil temperature under over load and over speed conditions for reliability in high speed low torque surface mounted PM synchronous motors(SPM). In the present study, the losses and coil temperature are measured under rated condition and calculated under over speed and over load conditions in the three different motors with 35PN440, 25PN250 and 15HTH1000. The heat transfer modeling has been performed based on acquired losses and temperature. The difference of coil temperature between heat transfer modeling and experiment is less than 6.4% under no load, over speed and over load conditions. Subsequently, the coil temperature of the motor with 15HTH1000 is 84.4% of the coil temperature of the motor with 35PN440 when speed is 0.9 and load is 3.0. The output of motor with 15HTH1000 is 85.2% greater than the output of the motor with 35PN440 when the dimensionless coil temperature is 1.0.