• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.216-223
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• 2019

The objective of this study is to propose a reliable stress-strain model in compression for lightweight concrete using bottom ash aggregates and air foam(LWC-BF). The slopes of the ascending and descending branches in the fundamental equation form generalized by Yang et al. were determined from the regression analyses of different data sets(including the modulus of elasticity and strains at the peak stress and 50% peak stress at the post-peak performance) obtained from 9 LWC-BF mixtures. The proposed model exhibits a good agreement with test results, revealing that the initial slope decreases whereas the decreasing rate in the stress at the descending branch increases with the increase in foam content. The mean and standard deviation of the normalized root-square mean errors calculated from the comparisons of experimental and predicted stress-strain curves are 0.19 and 0.08, respectively, for the proposed model, which indicates significant lower values when compared with those(1.23 and 0.47, respectively) calculated using fib 2010 model.

• Wind and Structures
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• v.11 no.1
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• pp.35-50
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• 2008

Wind and temperature have been shown to be the critical sources causing changes in the modal properties of large-scale bridges. While the individual effects of wind and temperature on modal variability have been widely studied, the investigation about the effects of multiple environmental factors on structural modal properties was scarcely reported. This paper addresses the modeling of the simultaneous effects of wind and temperature on the modal frequencies of an instrumented cable-stayed bridge. Making use of the long-term monitoring data from anemometers, temperature sensors and accelerometers, a neural network model is formulated to correlate the modal frequency of each vibration mode with wind speed and temperature simultaneously. Research efforts have been made on enhancing the prediction capability of the neural network model through optimal selection of the number of hidden nodes and an analysis of relative strength of effect (RSE) for input reconstruction. The generalization performance of the formulated model is verified with a set of new testing data that have not been used in formulating the model. It is shown that using the significant components of wind speeds and temperatures rather than the whole measurement components as input to neural network can enhance the prediction capability. For the fundamental mode of the bridge investigated, wind and temperature together apply an overall negative action on the modal frequency, and the change in wind condition contributes less to the modal variability than the change in temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.6
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• pp.400-408
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• 2008

Multipurpose Dam, it produces electric energy by converting the potential energy into kinetic energy utilizing its head and quantity of the water. However, in this process, since during the time when the turbine connected to the hydraulic turbine generator revolves, there occurs a ceaseless loud noise, and due to this condition, it is true state that those people who work at inside of the power plant are damaging as hard as they are unable to concentrate on their work. Not only this, because the hydro-electric power generator room that locates at middle section between the hydraulic turbine room and the office is very large space volume, also since it was constructed chiefly by the reflecting material, it is functioning of amplify the noise when operating the generator, the soundproof measure against this condition is necessitated. On such viewpoint, I have presented the problem point of the relevant Hydraulic turbine dynamo and Hydraulic turbine dynamo room, and after improve such problem point, this study has ever investigated the satisfying degree about the noise-reduction at before and after of the improvement of soundproof measure, using the Auralizational technique that can experience virtual acoustic field. It is considering that such result could be utilized usefully as the fundamental material hereafter for the acoustic performance of the hydro-electric power generator room in dam and when its construction.

• Journal of the Korean Society for Railway
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• v.16 no.3
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• pp.233-239
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• 2013

This paper studied the stress of Metropolitan Transit driving crews. Stress to such workers can not only lead to fatalities and infrastructure damage but also enormous loss of competitiveness. The study was carried out to search for ways of alleviating stress of driving crews. In order to reduce the various factors that exacerbate job stress of driving crews of Metropolitan Transit, it is first necessary to expand training in order to enhance their expertise, and improve facilities to protect driving crews in the event of accidents. Second, psychological compensation or organization's systems may cause job stress. It may therefore be possible to solve fundamental problems through typical organization level approach such as leadership training programs. Third, job stress may be reduced through proper life habits such as personal regular exercise. Fourth, we need to improve driving crews' working conditions and adjust working hours by avoiding excessive performance competition and an unfair evaluation system, by understanding their mental states, and by setting up systems such as a comprehensive health improvement and management program at the organization level.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1303-1314
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• 2019

This paper studies the harmonic characteristics of ship electric propulsion systems and their treatment methods. It also adopts effective measures to suppress and prevent ship power systems from affecting ship operation due to the serious damage caused by harmonics. Firstly, the harmonic characteristics of a ship electric propulsion system are reviewed and discussed. Secondly, aiming at problems such as resonant frequency and filter characteristics variations, resonance point migration, and unstable filtering performances in conventional passive filters, a method for fully tuning of a passive dynamic tunable filter (PDTF) is proposed to realize harmonic suppression. Thirdly, to address the problems of the uncontrollable inductance L of traditional air gap iron core reactors and the harmonics of power electronic impedance converters (PEICs), this paper proposes an electromagnetic coupling reactor with impedance transformation and harmonic suppression characteristics (ECRITHS), with the internal filter (IF) designed to suppress the harmonics generated by PEICs. The ECRITHS is characterized by both harmonic suppression and impedance change. Fourthly, the ECRITHS is investigated. This investigation includes the harmonic suppression characteristics and impedance transformation characteristics of the ECRITHS at the fundamental frequency, which shows the good performance of the ECRITHS. Simulation and experimental evaluations of the PDTF are carried out. Multiple PDTFs can be configured to realize multi-order simultaneous dynamic filtering, and can effectively eliminate the current harmonics of ship electric propulsion systems. This is done to reduce the total harmonic distortion (THD) of the supply currents to well below the 5% limit imposed by the IEEE-519 standard. The PDTF also can eliminate harmonic currents in different geographic places by using a low voltage distribution system. Finally, a detailed discussion is presented, with challenges and future implications discussed. The research results are intended to effectively eliminate the harmonics of ship electric power propulsion systems and to improve the power quality of ship power systems. This is of theoretical and practical significance for improving the power quality and power savings of ship power systems.

• Electronics and Telecommunications Trends
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• v.34 no.1
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• pp.75-85
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• 2019

Quantum technology is undergoing a revolution. Theoretically, strange phenomena of quantum mechanics, such as superposition and entanglement, can enable high-performance computing, unconditionally secure communication, and high-precision sensing. Such theoretical possibilities have been examined in the last few decades. The goal now is to apply these quantum advantages to daily life. Europe, where quantum mechanics was born a 100 years ago, is struggling to be placed at the front of this quantum revolution. Thus, the European Commission has decided to invest 1 billion EUR over 10 years and has initiated the ramp-up phase with 20 projects in the fields of communication, simulation, sensing and metrology, computing, and fundamental science. This program, approved by the European Commission, is called the "Quantum Technology Flagship" program. Its first objective is to consolidate and expand European scientific leadership and excellence in quantum research. Its second objective is to kick-start a competitive European industry in quantum technology and develop future global industrial leaders. Its final objective is to make Europe a dynamic and attractive region for innovative and collaborative research and business in quantum technology. This program also trains next-generation quantum engineers to achieve a world-leading position in quantum technology. However, the most important principle of this program is to realize quantum technology and introduce it to the market. To this end, the program emphasizes that academic institutes and industries in Europe have to collaborate to research and develop quantum technology. They believe that without commercialization, no technology can be developed to its full potential. In this study, we review the strategy of the Quantum Europe Flagship program and the 20 projects of the ramp-up phase.

• Journal of Korean Institute of Architectural Sustainable Environment and Building Systems
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• v.12 no.6
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• pp.531-542
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• 2018

Building energy demands have highly risen in modern society; thus, It is necessary to reduce building energy demands especially commercial buildings adopting a curtain wall architecture. Curtain wall architectures have a high ratio of windows which is a vulnerable in heat insulations as cladding. In order to complement insulation performance of windows in these buildings, there are various methods adopted often such as installing blinds, wing wall and films. There are two suggestions of this paper. 1) WWR (Window-to-Wall Ratio) makes a impaction of energy demands in buildings. 2) Another one is an efficiency of blind systems which are installed in buildings in order to reduce cooling demands. It is also critical to make fundamental model for low-energy building construction by processing a lot of simulation As a result by this study, 1) an external blind system is more useful for reducing cooling energy demands rather than an internal blind system. 2) Buildings which have a large window require more amount of cooling demands. In case of WWR 45%, it needs more cooling energy rather than WWR 15% model's 3) Adopting blind system would reduce energy demands. WWR 45% model with external blind systems reduces about 4% of cooling energy demands compared to same model without any blind systems.4) it is necessary to study an efficiency of blind systems combined with renewable energy and it will be possible to reduce more energy demand in building significantly.

• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.585-594
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• 2018

Chinese construction corporations take more market shares in the global construction market. The performance of Chinese construction corporations need to be reviewed from the capability and qualification system of the engineers including supervision engineer. The purpose of this study is to analyze the characteristics of professional qualifications for supervision engineer in China. The research methodology is to investigate the qualification exam system, process and examination subjects for searching the fundamental body of knowledge about supervision engineer qualification. The results shows that the qualification system in supervision engineer are classified in detail for the body of knowledge and operated by the government. The qualification examination requires broad and defied knowledge structure together with practical experiences. The research results may lead further research subjects of Chinese construction related qualifications and education system in the ways of more specificity, expertise, and practicality. The mutual understanding of qualification system becomes major issue to build better collaboration in global market.

• International journal of advanced smart convergence
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• v.8 no.1
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• pp.24-34
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• 2019

In this research, a practical deep learning framework to differentiate the lesions and nodules in breast acquired with ultrasound imaging has been proposed. 7408 ultrasound breast images of 5151 patient cases were collected. All cases were biopsy proven and lesions were semi-automatically segmented. To compensate for the shift caused in the segmentation, the boundaries of each lesion were drawn using Fully Convolutional Networks(FCN) segmentation method based on the radiologist's specified point. The data set consists of 4254 benign and 3154 malignant lesions. In 7408 ultrasound breast images, the number of training images is 6579, and the number of test images is 829. The margin between the boundary of each lesion and the boundary of the image itself varied for training image augmentation. The training images were augmented by varying the margin between the boundary of each lesion and the boundary of the image itself. The images were processed through histogram equalization, image cropping, and margin augmentation. The networks trained on the data with augmentation and the data without augmentation all had AUC over 0.95. The network exhibited about 90% accuracy, 0.86 sensitivity and 0.95 specificity. Although the proposed framework still requires to point to the location of the target ROI with the help of radiologists, the result of the suggested framework showed promising results. It supports human radiologist to give successful performance and helps to create a fluent diagnostic workflow that meets the fundamental purpose of CADx.

• The Journal of the Korean dental association
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• v.57 no.2
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• pp.52-63
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• 2019

Technological advances in contemporary medicine has discovered the causes of countless diseases and recorded a noticeable medical performance. As technology develops, the role of hospitals is expanding to include disease prevention of inpatients, on top of their fundamental role of treating diseases. Recently, hospitals are becoming more influential as they create environments to provide comfort and stability to patients. In this regard, contemporary hospitals are increasingly shifting their focus to create a patient-centric environment as well as develop into humanistic establishments. The same goes to dentists, as well. Since inpatients often have fear and frustration over treatment, hospitals should figure out the environmental factors that are more effective and relaxing for patients and design medical services to provide them. The patients' movement and spaces during their treatment were categorized by stages and collected for gazing information using eye tracking. It analyzed users' gaze information according to Heatmap analysis of distribution and frequency and was determined the presence or absence of stimuli on the components of space. This research is an advanced research to study and enhance treatment environment based on the analysis of patients' gazes. It attempted to create an opportunity to get closer to patient-centric environment by understanding the stimulants and obstacles and controlling the background settings.