• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.23-30
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• 2005

The Hygrothermal aging of the laminates of $Avimid^(R)$ K3B/IM7 in $80^{\circ}C$ water was studied as a function of immersion time prior to forming microcracks. The factors causing the $80^{\circ}C$ water to degradation of the laminates could be the degradation of the matrix toughness, the change in residual stresses or the interfacial damage between the fiber and the matrix. The times to saturation in $80^{\circ}C$ water for the laminates and for the neat resin were 100 hours and 500 hours. After 500 hours aging of the neat resin, the glass transition temperature was changed less than 1% by DSC test, and the weight gain was 1.55% increase with the diffusion coefficient $7\times10^{-6}m/s^2$ and the fracture toughness was decreased about 41%. After 100 hours fully saturated aging of the ${[+45/0/-45/90]}_s$ K3B/IM7 laminates in $80^{\circ}C$ water, the weight gain was 0.41% increase with the diffusion coefficient $1\times10^{-6}m/s^2$. In 100 hours, the loss of the fracture toughness of the laminates was 43.8% of the original toughness by the microcracking fracture toughness criterion. Therefore, the main factor to degrade the microcracking toughness of the laminates could be the degradation of the matrix fracture toughness.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.124-132
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• 2016

In order to estimate the effect of flow distributors connected to an upper nozzle of CMT(Core Makeup Tank) on the thermal-hydraulic characteristics in the tank, a simplified 2 inch Small Break Loss of Coolant Accident(SBLOCA) was simulated by skipping the decay power and Passive Residual Heat Removal System(PRHRS) actuation. The CMT is a part of safety injection systems in the SMART (System Integrated Modular Advanced Reactor). Each test was performed with reliable boundary conditions. It means that the pressure distribution is provided with repeatable and reproducible behavior during SBLOCA simulations. The maximum flow rates were achieved at around 350 seconds after the initial opening of the isolation valve installed in CMT. After a short period of decreased flow rate, it attained a steady injection flow rate after about 1,250 seconds. This unstable injection period of the CMT coolant is due to the condensation of steam injected into the upper part of CMT. The steady injection flow rate was about 8.4% higher with B-type distributor than that with A-type distributor. The gravity injection during hot condition tests were in good agreement with that during cold condition tests except for the early stages.

• Tunnel and Underground Space
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• v.30 no.5
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• pp.462-472
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• 2020

Rock classification is fundamental discipline of exploring geological and geotechnical features in a site, which, however, may not be easy works because of high diversity of rock shape and color according to its origin, geological history and so on. With the great success of convolutional neural networks (CNN) in many different image-based classification tasks, there has been increasing interest in taking advantage of CNN to classify geological material. In this study, a feasibility of the deep CNN is investigated for automatically and accurately identifying rock types, focusing on the condition of various shapes and colors even in the same rock type. It can be further developed to a mobile application for assisting geologist in classifying rocks in fieldwork. The structure of CNN model used in this study is based on a deep residual neural network (ResNet), which is an ultra-deep CNN using in object detection and classification. The proposed CNN was trained on 10 typical rock types with an overall accuracy of 84% on the test set. The result demonstrates that the proposed approach is not only able to classify rock type using images, but also represents an improvement as taking highly diverse rock image dataset as input.

• Geotechnical Engineering
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• v.13 no.5
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• pp.89-100
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• 1997

It is very improtant to evaluate the reliable nonlinear deformational characteristics of soils not only in the analysis of geotechnical structures under working stress conditions but also for the soil dynamic problems. Field testings such as crosshole and pressuremeter tests can be used to determine the modulus of soils under in-situ conditions, but it is not possible to determine the modulus over the entire strain amplitude range. Laboratory methods such as resonant column 1 torsional shear test can be used to determine the modulus over the whole strain amplitude range, but it is very difficult to obtain the representative undisturbed samples on the sixte. For the reliable evaluation of nonlinear deformation characteristics of soils on a typical site, small strain modulus obtained from field testy and nomalized modulus reduction curve determined by laboratory bests need to be combined. In this paper, laboratory and Held testy were performed at a sixte which consisted of granite wearthered residual boils to evaluate the nonlinear deformational characteristics of coils such as the effects of strain amplitude, loading frequency, confining pressure and sample disturbance. It has been shorn that when the effects of these factors are properly taken into account, the stiffness values evaluated by various field and labrotary tests are comparable to each other fairly well. Finally, the procedure to evaluate the nonlinear deformstional characteristics of the sixte was proposed.

• Polymer(Korea)
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• v.25 no.1
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• pp.98-107
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• 2001

Dielectric properties and shape memory characteristics of SBS composites filled with carbon black as conductive filler and (Ba,Ca)$(Sn,Ti)O_3$ or $SrTiO_3$ as dielectrics were investigated for the development of phantom model. SBS/carbon black composite showed an increment of complex dielectric constant with increasing the content of carbon black and the frequency dependence that the dielectric constant decreases with the frequency. The complex dielectric constant and the conductivity of SBS/carbon black/dielectrics composites increased with the increase of dielectrics and the characteristics of the frequency dependence also occurred by the effect of carbon black. Phantom materials with the dielectric properties and the conductivity corresponding to human tissues for the measurement of specific absorption rate(SAR) within the frequency range of current mobile phones(775MHz~2GHz) could be developed by adjusting the composition ratios of carbon black, dielectrics and SBS and by controlling the characteristic of frequency dependence of composite. From thermomechanical cycling test good shape recoverability could be obtained in SBS composite even though the residual strain was increased by the effect of filler.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.3 s.26
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• pp.23-34
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• 2003

Currently, the efficiency of GPS has been increased in the various precise survey like as the control survey and the navigation etc. Also, it is widely used in the deformation analysis of the structure, the measurement of the marine tides, the measurement of the river level and the topographic monitoring of seabed or riverbed by combined the measurement equipment for depth. In this study, we intend to increase in efficiency of the topographic monitoring of seabed or riverbed by combined with DGPS, RTK GPS and echo sounder. For this study, we defined the error correction of the echo sounder with the experiment of water tank which is considered the characteristic of estuary riverbed and then we developed the s/w for 3-dimensional monitoring of estuary riverbed and applied the s/w to field test and improved the various problems. On analyzing topography of estuary riverbed by combined GPS with echo sounder, the draught error which is yielded to change of length from the water surface by the movement of survey vessel to the end of the transducer was eliminated by geometrical rearrangement and we defined the correction formula $z=BM+SAH-DBR_{(i)}-DRT-ED$. The sounding error about the echo sounder and characteristic of estuary riverbed was found by understanding the relation of average diameter ind residual error and we defined correction formula, $Y=0.00474{\ast}ln(X)-0.0045$ by the regression analysis. and then we verified applicability of correction formula.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.204-209
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• 2015

The effluent limit of nickel from electroplating wastewater has been strengthened from 5 mg/L to 3 mg/L from 2014. However, currently applied treatment process for nickel plating wastewater is unable to meet the effluent limit, most of the treatment concept conducted by treatment plant is dilution with other metal bearing wastewater. This can cause very significant impact to the environment of nickel contamination. With this connection, the feasibility test has been conducted with the use of electrolysis by using sacrificial electrodes. Experiments were conducted in synthetic and electroless nickel plating wastewater. Optimal condition of current density, pH were derived from the synthetic wastewater. It was found that the removal efficiency of nickel exceeded 94% at the operation condition of at pH 9 and the current density of $1{\sim}2mA/cm^2$. At this conditions, the iron sludge was generated very low amount. However, it was unsuccessful to meet the effluent limit by applying these treatment conditions to the real electroplating wastewater. This can be explained due to the matrix effect of other metals and anions contained real electroplating wastewater. From the result of further study, the optimal conditions for the real wastewater treatment were found out to be at pH 9, current density $6{\sim}7mA/cm^2$, for 5 minutes of operating time. At these conditions, 88% removal of nickel was achieved, which results the residual nickel concentration was below 3 mg/L.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.210-217
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• 2006

The study was carried out to select the effective adjuvant as a photostabilizer for acetamiprid 5% SL(soluble concentrate) and to find its optimum content by using chemical and biological methods. Adjuvants used for the study were KS1 and KS2. Photodegradation test, insecticidal efficacies and residual analysis for the study were investigated. Although photodegradation rate of acetamiprid SL was decreased by addition of KS1 and KS2, the difference between KS1 and KS2 was not significant. As KS2 showed better efficacies against the cotton aphid (Aphis gossypii) and higher amount of residue on pepper than KS1, KS2 was selected as a photostabilizer for acetamiprid SL. Acetamipid SL with KS2 showed lower photodegradation rate, better efficacies against the cotton aphid (Aphis gossypii) and higher amount of residue on pepper as content of KS2 in acetamiprid SL was decreased. Therefore, it was concluded that the optimum content of KS2 was 0.1%. These results have demonstrated that the selected adjuvant could be used to enhance insecticidal activity and reduce spay dose of insecticide by protecting its photodegradation.

• The Korean Journal of Pesticide Science
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• v.8 no.4
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• pp.280-287
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• 2004

We investigated the residual amounts of endosulfan and procymidone taken by vegetables grown in hydroponics culture and field conditions treated with the pesticides in order to evaluate safe cultivation concentration of the pesticides in the vegetables. Endosulfan and procymidone were selected as test pesticides because they have been reported to frequently detect in agricultural products at different concentrations. In hydroponic culture, by Chinese cabbage, procymidone was absorbed 3.8 times higher than endosulfan. The higher the pesticide concentration get, the worse the plant grew. In soil treated with 10 mg/kg of endosulfan, the pesticide absorbed by Leafy radish, Chinese cabbage and radish was less then their MRLs. In case of carlot, the residue level in soil which did not exceed its MRL was 1 mg/kg. The concentrations of procymidone in soil which did not exceed the MRLs in Leafy radish, Chinese cabbage, radish and carrot were 10, 10, 2 and 1 mg/kg, respectively Usually aged endosulfan and procymidone residues were less absorbed into crops than the fresh ones. Chinese cabbage absorbed more endosulfan and pocymidone than leafy radish, radish doing more than carrot.

• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.70-78
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• 2009

Processing factors of pesticides in milling process of wheat grain, which are consumed and imported at large quantity were examined to establish reasonable MRL of the processed food. Azinphos-methyl, chlorpyrifos, chlorpyrifos-methyl, fenitrothion, malathion, and trichlorfon were selected for the study according to annual usage and the previous detection record in wheat grain. Dipping process for pesticide application was performed in laboratory, while milling process was conducted under pilot plant system. Processing factors were calculated by analyzing residual pesticides on wheat grain and processing products as wheat flour, bran and red dog. Processing factors were 0.05 for azinphos-methyl, 0.06 for chlorpyrifos, 0.05 for chlorpyrifos-methyl, 0.07 for fenitrothion, 0.07 for malathion, 0.06 for trichlorfon, respectively. Recovery test was also performed to establish extraction efficiency of analytical procedure. The recovery value ranged from 93.2% to 98.6% with standard deviation of 0.1-0.9%.