• Transactions of Materials Processing
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• v.31 no.4
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• pp.229-239
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• 2022

Convolution Neural Network(CNN) is a class of deep learning algorithms and can be used for image analysis. In particular, it has excellent performance in finding the pattern of images. Therefore, CNN is commonly applied for recognizing, learning and classifying images. In this study, the surface defect classification performance of Al 6061 extruded material using CNN-based algorithms were compared and evaluated. First, the data collection criteria were suggested and a total of 2,024 datasets were prepared. And they were randomly classified into 1,417 learning data and 607 evaluation data. After that, the size and quality of the training data set were improved using data augmentation techniques to increase the performance of deep learning. The CNN-based algorithms used in this study were VGGNet-16, VGGNet-19, ResNet-50 and DenseNet-121. The evaluation of the defect classification performance was made by comparing the accuracy, loss, and learning speed using verification data. The DenseNet-121 algorithm showed better performance than other algorithms with an accuracy of 99.13% and a loss value of 0.037. This was due to the structural characteristics of the DenseNet model, and the information loss was reduced by acquiring information from all previous layers for image identification in this algorithm. Based on the above results, the possibility of machine vision application of CNN-based model for the surface defect classification of Al extruded materials was also discussed.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.139-139
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• 2022

Nature-based solutions (NBS) involved conservation or rehabilitation of natural ecosystems or the creation of natural processes in modified or artificial ecosystems to mimic natural processes for the improved management of water (UN-Water, 2018). This study investigated the relationship between microbial presence and survival to the pollutant treatment performance of seven different stormwater NBS managing urban stormwater runoff. In this study, seven different stormwater nature-based solution (NBS) was investigated to identify the relationship of microbial community to the pollutant removal performance of stormwater NBS. Based on this study, Proteobacteria was found to be the most dominant microorganism for all stormwater NBS and IS followed by Acidobacteria and Actinobacteria. Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, WS3, and AF234118_p were found to have high positive correlation to most pollutant removal efficiency of different stormwater NBS (r-value: 0.62 to 0.68). Using Proteobacteria and Acidobacteria count in stormwater NBS, equations predicting pollutant removal performance were also developed and may be used in minimizing the cost for stormevent monitoring to identify the pollutant removal performance of stormwater NBS.

• Journal of Hydrogen and New Energy
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• v.31 no.6
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• pp.622-629
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• 2020

The performance and cost of electric vehicles (EVs) are much influenced by the performance and service life of the Li-ion battery system. In particular, the cell performance and reliability of Li-ion battery packs are highly dependent on their operating temperature. Therefore, a novel battery thermal management is crucial for Li-ion batteries owing to heat dissipation effects on their performance. Among various types of battery thermal management systems (BTMS'), the phase change material (PCM) based BTMS is considered to be a promising cooling system in terms of guaranteeing the performance and reliability of Li-ion batteries. This work is mainly concerned with the basic research on PCM based BTMS. In this paper, a basic experimental study on PCM based battery cooling system was performed. The main purpose of the present study is to present a comparison of two PCM-based cooling systems (n-Eicosane and n-Docosane) of the unit 18650 battery module. To this end, the simplified PCM-based Li-ion battery module with two 18650 batteries was designed and fabricated. The thermal behavior (such as temperature rise of the battery pack) with various discharge rates (c-rate) was mainly investigated and compared for two types of battery systems employing PCM-based cooling. It is considered that the results obtained from this study provide good fundamental data on screening the appropriate PCMs for future research on PCM based BTMS for EV applications.

• Animal Bioscience
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• v.35 no.4
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• pp.567-576
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• 2022

Objective: An experiment was conducted to determine the effect of algae-based antioxidant containing Se yeast (EconomasE^®) on the growth performance, visceral organ weight, meat quality, and oxidative stability of broiler chickens. Methods: Nine hundred sixty, day-old male broiler chickens (Cobb, 43.97±0.55 g) were divided into three dietary treatments and allocated into 12 deep litter pens in a completely randomized design giving 4 replicate cages for each treatment. Three dietary treatments were: i) control (CON, basal diet with sufficient nutrient), ii) vitamin E (VitE, basal diet supplemented with 100 IU VitE), and iii) Algae-based antioxidant containing Se yeast (EcoE, basal diet supplemented with 0.2% algae-based antioxidant containing Se yeast: EconomasE^®). Maize soybean meal based basal diets were formulated to meet or exceed the nutrition requirement for broiler chickens. Chickens were fed ad-libitum experimental diets during the 42 days experiment period. On days 21 and 42, body weight and feed intake were measured to calculate the feed conversion ratio of the chickens. Intestine and visceral organs were measured together with meat quality and oxidative stability on days 14 and 42. Results: Chickens fed with EcoE showed improved (p<0.05) growth performance, meat quality, and higher (p<0.05) oxidative stability compared to the chicken fed on CON. Moreover, broiler chickens fed with EcoE showed similar (p<0.05) growth performance with better (p<0.05) meat quality and higher oxidative stability compared to the broiler chickens fed VitE (p<0.05). Conclusion: The algae-based antioxidant containing Se yeast can be supplemented into commercial broiler diets as a substitution of VitE while maintaining growth performance with enhancing meat quality and oxidative stability of the broiler chickens.

• Earthquakes and Structures
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• v.10 no.2
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• pp.463-482
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• 2016

Air Traffic Control (ATC) towers play significant role in the functionality of each airport. In spite of having complex dynamic behavior and major role in mitigating post-earthquake problems, less attention has been paid to the seismic performance of these structures. Herein, seismic response of an existing ATC tower with a wall-frame structural system that has been designed and detailed according to a local building code was evaluated through the framework of performance-based seismic design. Results of this study indicated that the linear static and dynamic analyses used for the design of this tower were incapable of providing a safety margin for the required seismic performance levels especially when the tower was subjected to strong ground motions. It was concluded that, for seismic design of ATC towers practice engineers should refer to a more sophisticated seismic design approach (e.g., performance-based seismic design) which accounts for inelastic behavior of structural components in order to comply with the higher seismic performance objectives of ATC towers.

• The Korean Journal of Emergency Medical Services
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• v.20 no.3
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• pp.69-83
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• 2016

Purpose: The purpose of this study was to explore the factors influencing evidence-based fall prevention nursing performance of hospital nurses. Methods: A self-reported questionnaire was completed by 344 nurses from three general hospitals from January 20 to March 10, 2013. The study instruments included general characteristics of the subjects, and awareness and performance of fall prevention. Data were analyzed by t test, ANOVA, Pearson's correlation, and multiple regression using SPSS v. 20.0. Results: There were statistically significant differences in awareness and performance according to age, marital status, clinical experiences, workplace, experience of fall prevention education, knowledge of fall prevention, compliance with fall prevention, attention level toward prevention, recognition level of potential falls, nurse responsibility for falls, importance of fall prevention, efforts level for fall prevention, and awareness score of falls prevention. There was a positive correlation among awareness and performance of fall prevention. Based on the multiple regression analysis, compliance with fall prevention, efforts level for fall prevention, and awareness score of falls prevention were significant predictors for performance of fall prevention. The explanation power of the model was 64.1%. Conclusion: The findings revealed the need to develop an effective nursing intervention to improve hospital nurses' performance for fall prevention.

• The Journal of Information Systems
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• v.16 no.2
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• pp.1-33
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• 2007

Selecting and implementing competitive strategies based on e-business is extremely important since it determines if an enterprise can continue to grow or not. Accordingly, systematic and empirical study on the implementation of e-business based on competitive strategy is required, and in-depth studies considering various e-business development stages of enterprises are also needed. The purpose of this study is to present guideline for the staff in charge and managers of enterprises to achieve competitive advantage and to increase organizational performance in e-business environments. What we have found are as follows. (1) Factors greatly influencing on competitive strategy selection through e-business were environmental uncertainty, centralization, innovative culture, technological competence, and formalization. (2) Results of the relationship between competitive strategies and e-business performance showed that each strategy had different effects on financial performance, process performance, and customer performance. and (3) Data analysis between internal and external environmental factors and competitive strategy by each e-business development stage proved that the relationships between competitive strategy and e-business performance were different based on e-business development stage. Implications of the study and guidelines for the managers are provided in the paper.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.2
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• pp.97-105
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• 2019

PURPOSE: This study examined the factors related to school-based activity performance in school-aged children with spastic cerebral palsy (CP). METHODS: The Gross Motor Function Systems (GMFCS), Manual Ability Classification System (MACS), Communication Function Classification System (CFCS) as functional classifications, and the physical activity performance of the School Function Assessment (SFA) were measured in 79 children with spastic CP to assess the student's performance of specific school-related functional activities. RESULTS: All the function classification systems were correlated significantly with the physical activity performance of the SFA ($r_s=-.47$ to -.80) (p<.05). The MACS (${\beta}=-.59$), GMFCS (${\beta}=-.23$), CFCS (${\beta}=-.21$), and age (${\beta}=-.15$) in order were predictors of the physical activity performance of the SFA (84.8%)(p<.05). CONCLUSION: These functional classification systems can be used to predict the school-based activity performance in school-aged children with CP. In addition, they can contribute to the selection of areas for intensive interventions to improve the school-based activity performance.

• Journal of the Korean Solar Energy Society
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• v.39 no.2
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• pp.45-55
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• 2019

More than 76% of the detached houses in Korea are over 20 years old. These old detached houses have poor energy efficiency. According to the 2017 Housing Census (Statistics Korea), more than 50% of low-income families live in detached houses. Therefore, the improvement of energy efficiency in old detached houses is needed from the viewpoint of energy welfare. The general method of building energy modelling for the verification of energy efficiency is based on the construction year data of "Building Design Criteria for Energy Saving" due to the cost and time involved in collecting the thermal performance data of buildings. There is poor accuracy with the deterioration of long-term aging of building materials. Also, the selection of alternatives for energy performance improvement is based on the items to be applied, not a performance improvement goal. It is difficult to calculate energy performance that reflects variations in various parameters with dynamic energy simulations. In this study, the influence of long-term aging is used to accurately predict the energy performance of old detached houses. The building energy modelling method is called ENERGY#, which is a static analysis method based on ISO13790. Energy performance is evaluated by a combination of input variables including building orientation, insulation of walls and roof, thermal performance of windows and window/wall ratio, and infiltration rate. Finally, this study provides a way to determine alternatives that meet energy performance improvement goals.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1143-1148
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• 2011

In this study, seismic structural reinforcement are carried out, based on the estimated seismic performance of underground box structures in urban railway, and displacement based design method was developed to enhance seismic performance of structures. New seismic reinforcement design method is proposed and compared with existing design methods. And presented an overview of the developed design methodology through a design example to verify the validity of that methods.