• Steel and Composite Structures
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• v.10 no.2
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• pp.129-149
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• 2010

The objective of this study is to formulate a general 3D material-structural analysis framework for the thermomechanical behavior of steel-concrete structures in a fire environment. The proposed analysis framework consists of three sequential modeling parts: fire dynamics simulation, heat transfer analysis, and a thermomechanical stress analysis of the structure. The first modeling part consists of applying the NIST (National Institute of Standards and Technology) Fire Dynamics Simulator (FDS) where coupled CFD (Computational Fluid Dynamics) with thermodynamics are combined to realistically model the fire progression within the steel-concrete structure. The goal is to generate the spatial-temporal (ST) solution variables (temperature, heat flux) on the surfaces of the structure. The FDS-ST solutions are generated in a discrete form. Continuous FDS-ST approximations are then developed to represent the temperature or heat-flux at any given time or point within the structure. An extensive numerical study is carried out to examine the best ST approximation functions that strike a balance between accuracy and simplicity. The second modeling part consists of a finite-element (FE) transient heat analysis of the structure using the continuous FDS-ST surface variables as prescribed thermal boundary conditions. The third modeling part is a thermomechanical FE structural analysis using both nonlinear material and geometry. The temperature history from the second modeling part is used at all nodal points. The ABAQUS (2003) FE code is used with external user subroutines for the second and third simulation parts in order to describe the specific heat temperature nonlinear dependency that drastically affects the transient thermal solution especially for concrete materials. User subroutines are also developed to apply the continuous FDS-ST surface nodal boundary conditions in the transient heat FE analysis. The proposed modeling framework is applied to predict the temperature and deflection of the well-documented third Cardington fire test.

• Journal of Korean Medicine for Obesity Research
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• v.2 no.1
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• pp.13-23
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• 2002

Background & Methods: In order to study the effect of electro-lipolysis-acupuncture, 57 outpatients who have had herbal medication in Kirin Oriental Hospital were devided to two groups; acupuncture-treated group(46) vs non-acupuncture-treated group(11) Acupuncture-treated group was given electro-lipolysis-acupuncture at least two times a week and administered with herbal diet medication, whereas non-acupuncture-treated group was administered only with herbal diet medication. Results: Mean age, body weight and BMI of these two group at the start point of the treatment were $27.22({\pm}7.64)\;vs \;29.09({\pm}8.73),\;67.76({\pm}9.34)\;vs\;67.00({\pm}10.69),\;and\;26.20({\pm}3.02)\;vs\;26.14({\pm}4.10)$ in the order of acupuncture-treated and non-acupuncture groups. After one month of treatment, change rate of body weight, BMI, total fat, percentage of fat was significantly higher in acupuncture-treated group. Also the change rate of arm circumference, hip circumference and thigh circumference was significantly higher in acupuncture-treated group. The change rate of abdominal circumference and WHR of acupuncture-treated group was higher than that of non-acupuncture-treated group with no statistical significance. The circumference reduction rate according to herbal dieting program was higher in this order, abdomen, arms, chest, thighs and hips. On the other hand, chest circumference change rate over weight loss rate, which is the portion no acupuncture treatment was given to, and AMC change rate was higher in non-acupuncture-treated group. Conclusion: These results imply that herbal dieting program combined with electro-lipolysis-acupuncture is more effective on reducing body fat, size reduction of localized obesity and preservation of muscle than herbal prescription only dieting program.

• Computers and Concrete
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• v.23 no.3
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• pp.161-170
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• 2019

This paper aims at presenting a numerical method for estimating the elastic modulus of recycled concrete with crushed aggregates. In the method, polygonal aggregates following a given sieve curve are generated, and placed into a square simulation element with the aid of the periodic boundary condition and the overlap criterion of two polygonal aggregates. The mesostructure of recycled concrete is reconstructed by embedding an old interfacial transition zone (ITZ) layer inside each recycled aggregate and by coating all the aggregates with a new ITZ layer. The square simulation element is discretized into a regular grid and a representative point is selected from each sub-element. The iterative method is combined with the fast Fourier transform to evaluate the elastic modulus of recycled concrete. After the validity of the numerical method is verified with experimental results, a sensitivity analysis is conducted to evaluate the effects of key factors on the elastic modulus of recycled concrete. Numerical results show that the elastic modulus of recycled concrete increases with the increase of the total aggregate content and the elastic moduli of old and new ITZ but decreases with increasing the replacement ratio of recycled aggregate and the thicknesses of old and new ITZ. It is also shown that, for a replacement ratio of recycled aggregate smaller than 0.3, the elastic modulus of recycled concrete is reduced by no more than 10%.

• Biomedical Engineering Letters
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• v.8 no.4
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• pp.383-392
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• 2018

For prompt gamma ray imaging for biomedical applications and environmental radiation monitoring, we propose herein a multiple-scattering Compton camera (MSCC). MSCC consists of three or more semiconductor layers with good energy resolution, and has potential for simultaneous detection and differentiation of multiple radio-isotopes based on the measured energies, as well as three-dimensional (3D) imaging of the radio-isotope distribution. In this study, we developed an analytic simulator and a 3D image generator for a MSCC, including the physical models of the radiation source emission and detection processes that can be utilized for geometry and performance prediction prior to the construction of a real system. The analytic simulator for a MSCC records coincidence detections of successive interactions in multiple detector layers. In the successive interaction processes, the emission direction of the incident gamma ray, the scattering angle, and the changed traveling path after the Compton scattering interaction in each detector, were determined by a conical surface uniform random number generator (RNG), and by a Klein-Nishina RNG. The 3D image generator has two functions: the recovery of the initial source energy spectrum and the 3D spatial distribution of the source. We evaluated the analytic simulator and image generator with two different energetic point radiation sources (Cs-137 and Co-60) and with an MSCC comprising three detector layers. The recovered initial energies of the incident radiations were well differentiated from the generated MSCC events. Correspondingly, we could obtain a multi-tracer image that combined the two differentiated images. The developed analytic simulator in this study emulated the randomness of the detection process of a multiple-scattering Compton camera, including the inherent degradation factors of the detectors, such as the limited spatial and energy resolutions. The Doppler-broadening effect owing to the momentum distribution of electrons in Compton scattering was not considered in the detection process because most interested isotopes for biomedical and environmental applications have high energies that are less sensitive to Doppler broadening. The analytic simulator and image generator for MSCC can be utilized to determine the optimal geometrical parameters, such as the distances between detectors and detector size, thus affecting the imaging performance of the Compton camera prior to the development of a real system.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.4
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• pp.199-205
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• 2018

So many fast motion estimation algorithms for prediction quality and computational reduction have been published due to tremendous computations of full search algorithm. In the paper, we suggest an algorithm that reduces computation effectively, while keeping prediction quality as almost same as that of the full search. The proposed algorithm based on multiple threshold filter calculates the sum of partial block matching error for each candidate, selects the candidates for the next step, compares the stability of optimal candidates with minimum error, removes impossible candidates, and calculates optimal motion vectors by determining the progress of the next step. By doing that, we can find the minimum error point as soon as possible and obtain the better performance of calculation speed by reducing unnecessary computations. The proposed algorithm can be combined with conventional fast motion estimation algorithms as well as by itself, further reduce computation while keeping the prediction quality as almost same as the algorithms, and prove it in the experimental results.

• Journal of Engineering Education Research
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• v.21 no.6
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• pp.63-73
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• 2018

This research aims to analyze core competencies of engineering students in Korea as well as to explore the application plans of extracurricular activities(hereafter, ECA) and programs in order to enhance their core competencies. Participation in ECA has long been recognized as having positive benefits and impacts upon students. To achieve the purpose of this study, first, we investigated whether there were differences between core competencies in undergraduates according to majors, gender and grades. 'Core competencies', first introduced in management theory as 'core competency' can be defined as personal attributes or underlining characteristics, capable of delivering a role or job. 'Core competencies' has received particular attention in recent years and there has been much related research (domestic and foreign) combined with diverse factors. However, few studies have addressed the question on engineering student's core competencies as well as the ways of their enhancement. This study was conducted with a total of 286 students, and core competencies have been measured online, through K-CESA. Our findings show that firstly, there were significant differences in undergraduate students' core competencies by majors. Engineering students scored significantly lower in core competencies overall. Second, there was no significant difference in students' core competencies by gender and grade. Third, there was a significant correlation among components of core competencies. Finally, there was a significant correlation between core competencies and grades(GPA, grades in major subject & liberal arts subject), rather levels in the correlation were low. Furthermore, the study suggested that the appropriate application of extracurricular activities would enhance core competencies of students.

• Journal of Korea Multimedia Society
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• v.22 no.5
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• pp.535-546
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• 2019

Recently, there have been a lot of researches on the whole face replacement system, but it is not easy to obtain stable results due to various attitudes, angles and facial diversity. To produce a natural synthesis result when replacing the face shown in the video image, technologies such as face area detection, feature extraction, face alignment, face area segmentation, 3D attitude adjustment and facial transposition should all operate at a precise level. And each technology must be able to be interdependently combined. The results of our analysis show that the difficulty of implementing the technology and contribution to the system in facial replacement technology has increased in facial feature point extraction and facial alignment technology. On the other hand, the difficulty of the facial transposition technique and the three-dimensional posture adjustment technique were low, but showed the need for development. In this paper, we propose four facial replacement models such as 2-D Faceswap, OpenPose, Deekfake, and Cycle GAN, which are suitable for the Cox platform. These models have the following features; i.e. these models include a suitable model for front face pose image conversion, face pose image with active body movement, and face movement with right and left side by 15 degrees, Generative Adversarial Network.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.195-203
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• 2019

The aim of this study is to explore the paradigm shifts in culture and system related to life in terms of AI and the present point of view in which creating human values together are important. An approach that focuses on how AI-related phenomena work in modern society forms the basis of this research. Therefore, to clarify the meaning of "AI phenomenon" converging it as a part of social culture, this study was intended to find out the value incorporated in the social system such as ethics and equality together with the literature review. Inferring the technical culture that are combined with the AI that the members of society can do together is as important as technical understanding in the functional aspect. Therefore, this study was intended to suggest new culture that the cultural imagination and the social system create harmonizing each other, that is, the possibility of "AI culture". So, this article has a characteristic of a preliminary study, too.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.24-30
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• 2019

The deck floor of a the cargo truck becomesis damaged and aged due to the continuous loading of the loading cargo and external environmental factors. Floor boards made of wood and metal are often used. In the case of wood, the cost is high due to the use of imported wood, and the strength is easily deterioratesd due to environmental factors. In the case of metal materials, the durability is higher than that of wood, but problems are raised due to the effect of major factors that hinder the weight reduction, and the effects of corrosion. In order to replace this stucturestructural design, this study proposed a wood fiber composite using natural raw materials. Woody composites are being used as environmentally and friendly exterior materials with the combined advantages of plastic, and wood,; low cost and low density. However, due to the nature of the woody composites, the properties are differentdiffer depending on the contents of the matrix, reinforcing agent, additives, compatibilizer, etc. In this study, we investigate these problems through analysis of the microstructure and mechanical properties according to proper content and injection molding conditions. As a result, it is considered that the wood deck composite can replaced the current Deck Floor Boardreplace current deck floor boards through continuous continued research and results of this study.

• Journal of the Korea Convergence Society
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• v.10 no.5
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• pp.85-94
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• 2019

This study was aimed to identify a study on the effect of chest compressions combined with abdominal drawing-in technique on prevention of back pain and chest compression quality. We tested motion analysis, electromyography, and chest compression quality of 15 paramedics. Data were normalized to SPSS 21.0 (Kolmogorov-Smirnov and Shapiro-Wilk test). The paired t-test was used for the pre- and post-test chest compressions, the one-way ANOVA was used for the analysis of the measurement point-in-time differences, and LSD was used for the post-test. The results of the study showed significant difference in muscle activity and chest compression success rate when the chest pressure was applied with abdomen drawing-in. Therefore, it is necessary to study cardiopulmonary resuscitation education which can increase the chest compression success rate while preventing the back pain of the paramedics in the future.