• Steel and Composite Structures
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• v.38 no.1
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• pp.17-31
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• 2021

Post-earthquake fire is a common disaster which causes serious safety issues to infrastructures. This study aims to investigate the residual loading capacities of circular concrete-filled steel tube (CFST) columns under post-earthquake fire experimentally and numerically. The experimental programme contains two loading steps - pre-damage cyclic loading at room temperature and transient state tests with constant compression loads. Three finite element models are developed and validated against the test results. Upon validation, a total of 48 numerical results were generated in the parametric study to investigate the effects of thickness and strengths of steel tube, axial compression ratio and damage degree on the fire resistance of circular CFST columns. Based on the analysis on experimental and numerical results, the loading mechanism of circular CFST columns is discussed. A design method is proposed for the prediction of fire resistance time under different seismic pre-damage and compression loads. The predictions by the new method is compared with the newly generated experimental and numerical results and is found to be accurate and consistent with the mean value close to the unity and a coefficient of variation around 1%.

• Journal of Hydrogen and New Energy
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• v.32 no.3
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• pp.163-171
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• 2021

Securing energy sources is a key element essential to economic and industrial development in modern society, and research on renewable energy and hydrogen energy is now actively carried out. This research was conducted through experiments and analytical methods on the hydrogen filling process in the hydrogen storage tank of the hydrogen charging station. When low-temperature, high-pressure hydrogen was injected into a high-pressure tanks where hydrogen is charged, the theoretical method was used to analyze the changes in temperature and pressure inside the high-pressure tanks, the amount of hydrogen charge, and the charging time. The analysis was conducted in the initial vacuum state, called the First Cycle, and when the residual pressure was present inside the tanks, called the Second Cycle. As a result of the analysis, the highest temperature inside the tanks in the First Cycle of the high-pressure tank increased to 442.11 K, the temperature measured through the experiment was 441.77 K, the Second Cycle increased to 397.12 K, and the temperature measured through the experiment was 398 K. The results obtained through experimentation and analysis differ within ±1%. The results of this study will be useful for future hydrogen energy research and hydrogen charging station.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.65-75
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• 2021

This study explores multiple variables of an OTT service for discovering hidden relationship between rating and the other variables of each successful and failed content, respectively. In order to extract key variables that are strongly correlated to the rating across the contents, this work analyzes 170 Netflix original dramas and 419 movies. These contents are classified as success and failure by using the rating site IMDb, respectively. The correlation between the contents, which are classified via rating, and variables such as violence, lewdness and running time are analyzed to determine whether a certain variable appears or not in each successful and failure content. This study employs a regression analysis to discover correlations across the variables as a main analysis method. Since the correlation between independent variables should be low, check multicollinearity and select the variable. Cook's distance is used to detect and remove outliers. To improve the accuracy of the model, a variable selection based on AIC(Akaike Information Criterion) is performed. Finally, the basic assumptions of regression analysis are identified by residual diagnosis and Dubin Watson test. According to the whole analysis process, it is concluded that the more director awards exist and the less immatatable tend to be successful in movies. On the contrary, lower fear tend to be failure in movies. In case of dramas, there are close correlations between failure dramas and lower violence, higher fear, higher drugs.

• Composites Research
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• v.34 no.6
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• pp.337-344
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• 2021

In this study, the progressive failure behavior of the composite fan blade dovetail element under tensile loading is numerically investigated through finite element(FE) simulation. The accuracy of prediction by FE simulation is verified through tensile testing. The dovetail element is one of the joints for coupling the fan blade with the disk in a turbofan engine. The dovetail element is usually made of a metal material such as titanium, but the application of composite material is being studied for weight reduction reasons. However, manufacturing defects such as drop-off ply and resin pocket inevitably occur in realizing complex shapes of the fan blade made by composite materials. To investigate the effect of these manufacturing defects on the composite fan blade dovetail element, we performed numerical simulation with FE model to compare the prediction of the FE model and the tensile test results. At this time, the cohesive zone model is used to simulate the delamination behavior. Finally, we found that FE simulation results agree with test results when considering thermal residual stress and through-thickness compression enhancement effect.

• Journal of Ginseng Research
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• v.46 no.6
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• pp.771-779
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• 2022

Background: As a kind of common complication of the surgery of perianal diseases, perianal ulcer is known as a nuisance. This study aims to develop a kind of 20(S)-ginsenoside Rg3 (Rg3)-loaded hydrogel to treat perianal ulcers in a rat model. Methods: The copolymers PLGA₁₆₀₀-PEG₁₀₀₀-PLGA₁₆₀₀ were synthesized by ring-opening polymerization process and Rg3-loaded hydrogel was then developed. The perianal ulcer rat model was established to analyze the treatment efficacy of Rg3-loaded hydrogel for ulceration healing for 15 days. The animals were divided into control group, hydrogel group, free Rg3 group, Rg3-loaded hydrogel group, and Lidocaine Gel® group. The residual wound area rate was calculated and the blood concentrations of interleukin-1 (IL-1), interleukin-6 (IL-6), and vascular endothelial growth factor (VEGF) were recorded. Hematoxylin and eosin (H&E) staining, Masson's Trichrome (MT) staining, and tumor necrosis factor α (TNF-α), Ki-67, CD31, ERK1/2, and NF-κB immunohistochemical staining were performed. Results: The biodegradable and biocompatible hydrogel carries a homogenous interactive porous structure with 10 ㎛ pore size and five weeks in vivo degradation time. The loaded Rg3 can be released sustainably. The in vitro cytotoxicity study showed that the hydrogel had no effect on survival rate of murine skin fibroblasts L929. The Rg3-loaded hydrogel can facilitate perianal ulcer healing by inhibiting local and systematic inflammatory responses, swelling the proliferation of nuclear cells, collagen deposition, and vascularization, and activating ERK signal pathway. Conclusion: The Rg3-loaded hydrogel shows the best treatment efficacy of perianal ulcer and may be a candidate for perianal ulcer treatment.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.379-384
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• 2022

In a wireless sensor network, a large number of sensor nodes are deployed in an environment where direct access is difficult. It is difficult to supply power, such as replacing the battery or recharging it. It is very important to use the energy with the sensor node. Therefore, an important consideration to increase the lifetime of the network is to minimize the energy consumption of each sensor node. If the energy of the wireless sensor node is exhausted and discharged, it cannot function as a sensor node. Therefore, it is a method proposed in various protocols to minimize the energy consumption of nodes and maintain the network for a long time. We consider the center point and residual energy of the cluster, and the plot point and K-means (WSN suggests optimal clustering). We want to evaluate the performance of the KOCED protocol. We compare protocols to which the K-means algorithm, one of the latest machine learning methods, is applied, and present performance evaluation factors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1835-1845
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• 2021

To accurately identify black ice and warn the drivers of information in advance so they can control speed and take preventive measures. In this paper, we propose a lightweight black ice detection network based on infrared road images. A black ice recognition network model based on CNN transfer learning has been developed. Additionally, to further improve the accuracy of black ice recognition, an enhanced lightweight network based on MobileNetV2 has been developed. To reduce the amount of calculation, linear bottlenecks and inverse residuals was used, and four bottleneck groups were used. At the same time, to improve the recognition rate of the model, each bottleneck group was connected to a 3×3 convolutional layer to enhance regional feature extraction and increase the number of feature maps. Finally, a black ice recognition experiment was performed on the constructed infrared road black ice dataset. The network model proposed in this paper had an accurate recognition rate of 99.07% for black ice.

• The Journal of Engineering Geology
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• v.31 no.1
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• pp.19-30
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• 2021

This study evaluated the injection rate and the injection efficiency of the artificial recharge in the upper drought-prone watershed region, where the remaining water was used for injection, by using a numerical model to secure water during a drought. As a result of a numerical model under the condition of diverse injection rates per a well and hydraulic characteristics of the aquifer, the optimal injection rate per a well was estimated as 50.0 ㎥/day, and the injection efficiency was simulated as 33.2% to 81.2% of the total injection volume. As the injection time was shorter, the injection efficiency tented to increase non-linearly. As the injection rate increased, the residual storage in aquifer increased and available groundwater amount also increased, which could be advantageous for drought relief. For a more accurate assessment of injection efficiency, the model will be validated using the field injection data and optimum scenarios will enable the efficient operation of the artificial recharge system in the study area.

• The Journal of the Convergence on Culture Technology
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• v.8 no.3
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• pp.265-270
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• 2022

The purpose of this study is to derive the damage weak part of the elastic rail fastening system for concrete tracks (System 300-1). In the concrete tracks, the elastic rail fastening system sticks the rail and the sleeper and reacts all the time when the train is running. Among the components of the rail fastening system, the resilience pad and tension clamp were fatigue members and were constantly deformed in response to compressive and uplift forces. In this study, the residual deformation characteristics of the tension clamp according to the period of use were analyzed using by specimens taken on site in the same section for 6, 11, and 16 years on the serviced urban transit. In addition, the damage mechanisms for each component were derived based on finite element analysis. As a result of the numerical analysis, the stress (strain) of each part of the tension clamp according to the external force from the applied clamping force was analyzed to derive the damaged weak part of the tension clamp.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.969-974
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• 2022

In order to maximize dynamic range and to minimize image lag in digital X-ray imaging, diminishing residual parasitic capacitance in photodiode in pixels is critically necessary. These requirements are more specifically requested in dynamic X-ray imaging with high frame rate and low image lag for industrial 2D/3D automated X-ray inspection and medical CT imaging. This study proposes duoPIX^TM X-ray imaging sensor for the first time that is composed of reset thin film transistor, readout thin film transistor and photodiode in a pixel. To verify duoPIX^TM X-ray imaging sensor, designing duoPIX^TM pixel and imaging sensor was executed first then X-ray imaging sensor with 105 ㎛ pixel pitch, 347 mm × 430 mm imaging area and 3300 × 4096 pixels (13.5M pixels) was fabricated and evaluated by using module tester and image viewer specifically for duoPIX^TM imaging sensor.