• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.623-630
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• 2019

As the Asian region becomes strategically important in the international construction market, competition among construction firms has been more intense. While existing literature on the Asian construction market have mainly focused on qualitative approaches to market entry strategies and risk assessment, quantitative research to explain the dynamic competitive structure of the market has been rarely conducted. To address this issue, this study analyzes the structure of contract performance in the Asian region based on the data from 3,996 projects awarded to Korean construction firms from 2009 to 2017. In addition, this study applies a mathematical model using both static (market concentration) and dynamic (market mobility and instability) analyses. Consequently, the static analysis indicates that market concentration led by top-four firms tends to be increased, and on the dynamic aspect, the market position of Korean construction firms is recently weakened and fluctuated in most of the Asian regions and the construction sectors. The methodology and result of this paper would be meaningful not only to understand the underlying structure of industry-level performance but also to provide a useful reference for establishing competitive strategies towards the Asian market.

• Computers and Concrete
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• v.17 no.6
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• pp.787-799
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• 2016

Climate anomalies in recent years, numerous natural disasters caused by landslides and a large amount of entrained sands and stones in Taiwan have created significant disasters and greater difficulties in subsequent reconstruction. How to respond to these problems efficaciously is an important issue. In this study, the sands and stones were doped with recycled materials (waste LCD glass sand, slag powder), and material was mixed for recycled ready-mixed soil. The study is based on security and economic principles, using flowability test to determine the water-binder ratio (W/B=2.4, 2.6, and 2.8), a fixed soil: sand ratio of 6:4 and a soil: sand: glass ratio of 6:2:2 as fine aggregate. Slag (at concentrations of 0%, 20%, and 40%) replaced the cement. The following tests were conducted: flowability, initial setting time, unit weight, drop-weight and compressive strength. The results show that the slump values are 220 -290 mm, the slump flow values are 460 -1030 mm, and the tube flow values are 240-590 mm, all conforming to the objectives of the design. The initial setting times are 945-1695 min. The unit weight deviations are 0.1-0.6%. The three groups of mixtures conform to the specification, being below 7.6 cm in the drop-weight test. In the compressive strength test, the water-binder ratios for 2.4 are optimal ($13.78-17.84kgf/cm^2$). The results show that Recycled ready-mixed soil materials (RRMSM) possesses excellent flowability. The other properties, applied to backfill engineering, can effectively save costs and are conducive to environmental protection.

• Journal of the Korea Safety Management & Science
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• v.14 no.4
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• pp.205-210
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• 2012

We don't have time to waste, time is running, and the global warming is an issue that concerns to all of us. Information technology, which on a global level is responsible for 2% of emission of greenhouse gases. However, the remaining 98% is seen as an opportunity for IT to help our planet, our companies and our society. The purpose of this paper is to analyze green information technology (IT) initiatives and their strategic impact. And to have done this, we develope and create a very useful balanced-scorecard framework to explain, understand, and identify the direct and indirect contribution of green IT initiatives. The green IT evaluation framework, called here a sustainable green IT balanced scorecard, integrates the four BSC-IT perspectives with the Zuboff's automate/informate goals of information systems and the contribution of the sustainability (economic, social and environment). This study also seeks to answer the following questions: 1) what are the driving forces for implementing green IT initiatives? 2) How can an analytical framework be built to systematically analyze the benefits and strategic contribution of green IT initiatives? And 3) how green IT initiatives impact the strategic goals of a firm and how they can contribute to the triple bottom line? The framework demonstrates to be useful as a management tool to hopefully integrate environmental and social management with the general management of a company. Besides, the strategy map and measures for each cell of the framework are provided.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.6
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• pp.1261-1277
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• 2014

In recently, attracting foreign students are very active in lots of universities of South Korea. According to trend, foreign students who are studying in Korea have increased steadily. The programs to support and help them for adaptation of the university and academic success are rising though, on account of language barrier, it seems not easy to adapt to those people who finished studying korean language training that roles incubator and entered their major. More over, to expect personal training for them by professors is also difficult because of short of educational or executive and bankroll support in reality. Therefore it became a social issue about managing foreign students of South Korea. This study aimed to analyse the difficulties of learning from chinese international student's view. For this, we analysed focus group interview which intended 16 chinese foreign students and the collected data through reflective journal record using Nvivo program. In the results of focus group interview, learning difficulties of chinese foreign students are itemized 4 sections of personal aspect, environmental aspect, educational contents' aspect and educational methodic aspect. It is subdivided 11 sections and identified of requirement for studying support corresponding each part of difficulties. This research finding will be able to expect to provide a suggestion to looking for options for learning support plan of chinese foreign students.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.451-455
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• 2015

An excess application of N fertilizer causes physiological and morphological disorder known as ammonium ($NH_4{^+}$) toxicity in Chinese cabbage and it has been to be an issue for appropriate N fertilizer management. Hence, the pot experiment was conducted in order to evaluate the alleviating effect of the application of the easily decomposable carbohydrate on $NH_4{^+}$ toxicity in Chinese cabbage. Four levels of urea at 0, 160, 320, and $640kg\;N\;ha^{-1}$, represented as T1, T2, T3, and T4, respectively, were applied. In order to evaluate the alleviating effect of the application of the easily decomposable carbohydrate (sucrose) at T3 and T4 where $NH_4{^+}$ toxicity had occurred, five levels of sucrose were applied to meet C/N ratios of 0, 2, 4, 6, and 10, respectively. Our results showed that the $NH_4{^+}$ toxicity was observed at T3 and T4 at 5 days after treatment (DAT). $NH_4{^+}$ toxicity contributed to decrease fresh weight, length of leaves, length of root, and number of leaves significantly (p<0.05). The application of sucrose as a source of mitigating $NH_4{^+}$ toxicity had a good performance at T3 with the alleviating effect as 73 % and reduced in $NH_4{^+}-N$ content in soil at 29 DAT. In the maximum N rate of T4, however, sucrose application recovered it as 32 % only compared to T2 even though the same C/N ratio was treated. Consequently, sucrose as the easily decomposable carbohydrate played crucial role to reduce $NH_4{^+}$ concentration in soil and finally alleviated $NH_4{^+}$ toxicity in plant.

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.275-285
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• 2021

Algal bloom is an important issue in maintaining the safety of the drinking water supply system. Fast detection and classification of algae images are essential for the management of algal blooms. Conventional visual identification using a microscope is a labor-intensive and time-consuming method that often requires several hours to several days in order to obtain analysis results from field water samples. In recent decades, various deep learning algorithms have been developed and widely used in object detection studies. YOLO is a state-of-the-art deep learning algorithm. In this study the third version of the YOLO algorithm, namely, YOLOv3, was used to develop an algae image detection model. YOLOv3 is one of the most representative one-stage object detection algorithms with faster inference time, which is an important benefit of YOLO. A total of 1,114 algae images for 30 genera collected by microscope were used to develop the YOLOv3 algae image detection model. The algae images were divided into four groups with five, 10, 20, and 30 genera for training and testing the model. The mean average precision (mAP) was 81, 70, 52, and 41 for data sets with five, 10, 20, and 30 genera, respectively. The precision was higher than 0.8 for all four image groups. These results show the practical applicability of the deep learning algorithm, YOLOv3, for algae image detection.

• Journal of the Korea Society of Computer and Information
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• v.26 no.5
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• pp.31-38
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• 2021

This study empirically investigated the user's experience with based on the Technology Acceptance Model. According to the frequency analysis results, the usability for learning was evaluated relatively higher than that for appreciation from the perspective of perceived usefulness and the technical factors such as graphics and modeling raised the issue for the quality improvement. According to the results of the correlation analysis, the usability for learning correlated with the degree of satisfaction. In addition, all detailed factors of perceived ease of use positively influenced on the degree of satisfaction and the impact of the environmental factor on the degree of satisfaction was greatest. The degree of satisfaction with the VR application significantly correlated with the degree of immersion and behavioral intention to the VR application. Therefore, this study proved the suitability for the Technology Acceptance Model as a tool for evaluating a VR application.

• Membrane Journal
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• v.31 no.2
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• pp.120-132
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• 2021

Microbial fuel cell (MFC) is a bio-electrochemical device that generates electricity by utilizing bacterial catalytic activity that degrades wastewater. Proton exchange membrane (PEM) is the core component of MFC that decides its performance, and Nafion membrane is the most widely used PEM. In spite of the excellent performance of Nafion, it has drawbacks such as high cost, biofouling issue, and non-biodegradable property. Recent studies in MFC attempted to synthetize the alternative membrane for Nafion by incorporating various polymers, sulfonating, fluorinating, and doping other chemicals. This review summarizes characteristics and performances of different composite membrane based MFCs, mostly focusing on PEM.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.50-63
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• 2018

The issue of global warming and environmental pollutant has become an international concern due to the widespread use of fossil fuels, and thus waste heat recovery technologies has become important to improve energy utilization. The global market of power generation system using industrial waste heat is rapidly growing at an average rate of 5% due to its advantage of increasing energy efficiency. In order to design an optimal waste heat recovery system, it is necessary to develop a program that offers economic evaluation of each power generating technology according to the heat source conditions. In this paper, the economic analysis module to calculate LCOE is developed and verified the reliability against NETL economic analysis results. As a result of the verification, the error rate is about 6 ~ 7%, which satisfy the accuracy for business feasibility evaluation. In order to enhance the reliability, the module was improved by applying the levelization method used by NETL. As a result of the verification of reliability, the error rate is less than 1% and the accuracy is improved.

• Journal of Soil and Groundwater Environment
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• v.24 no.4
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• pp.1-10
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• 2019

Recently, groundwater contamination by mixed occurrence of arsenic (As) and nitrate ($NO_3{^-}$) has been a serious environmental issue all around world. In this study, we investigated the microbial As(III) oxidation characteristic under denitrification process to examine the feasibility of the microbial consortia in wetland sediment to simultaneously treat these two contaminants. The detail objectives of this study were to investigate the effects of $NO_3{^-}$ on the oxidation of As(III) in anaerobic environments and observe the microbial community change during the As oxidation under denitrification process. Results showed that the As(III) was completely and simultaneously oxidized to As(V) under denitrification process, however, it occurred to a much less extent in the absence of sediment or $NO_3{^-}$. In addition, the significant increase of As(III) oxidation rate in the presence of $NO_3{^-}$ suggested the potential of As oxidation under denitrification by indigenous microorganisms in wetland sediment. Genera Pseudogulbenkiania, and Flavisolibacter were identified as predominant microbial species driving the redox process. Conclusively, this study can provide useful information on As(III) oxidation under denitrifying environment and contribute to develop an effective technology for simultaneous removal of As(III) and $NO_3{^-}$ in groundwater.