• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.159-168
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• 2019

We examined the effect of Siemens ADMIRE (Advanced Modeled Iterative Reconstruction) on image quality by measuring changes in HU, noise, and SNR of background air, fat, muscle, and background signals on a chest CT scan. Experimental results show that as the ADMIRE Strength increases, the noise decreases and the signal increases, consequently the signal-to-noise ratio increases. ADMIRE can reduce noise by 28 ~ 61% compared to FBP, which is a conventional image reconstruction algorithm, and improves SNR by 16 ~ 100%.

• Journal of Advanced Research in Ocean Engineering
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• v.1 no.1
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• pp.55-62
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• 2015

Floating structure such as tension leg platform, semi-submersible and spar are widely used in field of oil exploration and renewable energy system. All of these structures have the base cylinder support structure which have effective rule in overall dynamic of response. So the accurate and reliable modeling is needed for optimum design and understanding the physical background of these systems. The aim of this article is an analytical discussion on stochastic modeling of floating cylinder based support structure but an applicable one. Due to this a mathematical mass-damper-spring system of a floating cylinder of HAWAII WTG offshore wind as an applicable and innovative system is adopted to model a coupled degrees using random vibration in analytical way. A fully develop spectrum is adopted to solve the stochastic spectrum analytically by a proper approximation. Some acceptable assumption is adopted. The simplified but analytical and innovative hydrodynamic analysis of this study not only will help researcher to concentrate more physically on hydrodynamic analysis of floating structures but also can be useful for any quick, simplified and closed form analysis of a complicated problem in offshore engineering.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.1
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• pp.1-19
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• 2014

Attaching a piezoelectric transducer to a vibrating structure, and shunting it with an electric circuit, gives rise to different passive, semi-passive, and semi-active control techniques. This paper attempts to review the research related to structural vibration control, via passive, semi-passive, and semi-active control methods. First, the existing electromechanical modeling is reviewed, along with the modeling methods. These range from lumped parameters, to distributed parameters modeling of piezostructural systems shunted by electrical networks. Vibration control laws are then discussed, covering passive, semi-passive, and semi-active control techniques, which are classified according to whether external power is supplied to the piezoelectric transducers, or not. Emphasis is placed on recent articles covering semi-passive and semi-active control techniques, based upon switched shunt circuits. This review provides the necessary background material for researchers interested in the growing field of vibration damping and control, via shunted piezostructural systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.315-323
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• 2015

Nowadays, it is expected that mobility loads such as electric railways and electric vehicles will be penetrated gradually and affect on the power system stability by their load characteristics. Various researches have been carried out about electric vehicles for the recent decade though the load of electric railway could be forecasted because of the specified path and timetable, is a field with a long historic background. Some precise 5th polynomial equations are required to analyze the power system stability considering mobility load to be increased in the immediate future while the electric railway dispatching simulator uses load models with constant power and constant impedance for the system analysis. In this paper, seasonal urban railway load models are established as the form of 5th polynomial equations and substation load modeling methods are proposed merging railway station load models and general load models. Additionally, load management effects by the load modeling are confirmed through the case studies, in which seasonal load models are developed for Seoul Subway Line No. 2, Gyeongui Line and Airport Railroad and the substation load change is analyzed according to the railway load change.

• Journal of Korea Multimedia Society
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• v.18 no.12
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• pp.1519-1527
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• 2015

TFT-LCD automatic defect inspection system for detecting defects in place of the visual tester does pre-processing, candidate defect pixel detection, and recognition and classification through a blob analysis. An over-detection result of defects acts as an undue burden of blob analysis for recognition and classification. In this paper, we propose defect detection method based on the histogram distribution modeling of TFT-LCD image to minimize over-detection of candidate defective pixels. Primary defect candidate pixels are detected estimating the skewness of the luminance distribution histogram of the background pixels. Based on the detected defect pixels, the defective pixels other than noise pixels are detected using the distribution histogram model of the local area. Experimental results confirm that the proposed method shows an excellent defect detection result on the image containing the various types of defects and the reduction of the degree of over-detection as well.

• Safety and Health at Work
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• v.6 no.1
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• pp.39-45
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• 2015

Background: Health and safety (H&S) on a construction site can either make or break a contractor, if not properly managed. The usage of Building Information Modeling (BIM) for H&S on construction execution has the potential to augment practitioner understanding of their sites, and by so doing reduce the probability of accidents. This research explores BIM usage within the construction industry in relation to H&S communication. Methods: In addition to an extensive literature review, a questionnaire survey was conducted to gather information on the embedment of H&S planning with the BIM environment for site practitioners. Results: The analysis of responses indicated that BIM will enhance the current approach of H&S planning for construction site personnel. Conclusion: From the survey, toolbox talk will have to be integrated with the BIM environment, because it is the predominantly used procedure for enhancing H&S issues within construction sites. The advantage is that personnel can visually understand H&S issues as work progresses during the toolbox talk onsite.

• Nuclear Engineering and Technology
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• v.43 no.4
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• pp.361-374
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• 2011

Two types of numerical modeling techniques were considered for the dynamic response of a structure subjected to a ground acceleration. One technique is based on the equation of motion relative to ground motion, and the other is based on the equation of absolute motion of the structure and the ground. The analytic background of the former is well established while the latter has not yet been extensively verified. The latter is called a large mass method, which allocates an appropriate large mass to the ground so that it causes the ground to move according to a given acceleration time history. In this paper, through the use of a single degree-of-freedom spring-mass system, the equations of motion of the two techniques were analyzed and useful theorems are provided on the large mass method. Using simple examples, the numerical results of the two modeling techniques were compared with analytic solutions. It is shown that the theorems provide a clear insight on the large mass method.

• Journal of the Ergonomics Society of Korea
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• v.32 no.5
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• pp.475-480
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• 2013

Objective: In this study, virtual reality was adopted to consider ergonomic factors in yacht design. Virtual human which is the same actual human was created in virtual environment using Digital Human Modeling which has been used in the manufacturing communities to design better workplaces and maximize the safety of workers. Background: During the past 40 years yachting has expanded from being, generally speaking, a minority sport - too expensive for the large majority of people - into a major recreational activity practiced by millions all over the world. Many new yacht designs have appeared and number of professional, as well as amateur designers has increased steadily. But they had not considered ergonomic factors in yacht design. Method: Worker's posture, traffic line and workload had been analyzed in sailing yacht. After the caution level was evaluated, we pointed out clues which had high workload and interference. To reduce workload, we applied ergonomic principles for improving working conditions and environments in Digital Human Model. Results: We found the space problems and workload of postures. Conclusion: (1) Unnatural posture of crews was sustained. (2) Workload that occurs in the human body was overloaded. (3) Crew's work space was very narrow. Application: This study will be applied the new ergonomic design of yacht.

• Journal of Information Processing Systems
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• v.14 no.4
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• pp.807-823
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• 2018

Speaker verification system performance depends on the utterance of each speaker. To verify the speaker, important information has to be captured from the utterance. Nowadays under the constraints of limited data, speaker verification has become a challenging task. The testing and training data are in terms of few seconds in limited data. The feature vectors extracted from single frame size and rate (SFSR) analysis is not sufficient for training and testing speakers in speaker verification. This leads to poor speaker modeling during training and may not provide good decision during testing. The problem is to be resolved by increasing feature vectors of training and testing data to the same duration. For that we are using multiple frame size (MFS), multiple frame rate (MFR), and multiple frame size and rate (MFSR) analysis techniques for speaker verification under limited data condition. These analysis techniques relatively extract more feature vector during training and testing and develop improved modeling and testing for limited data. To demonstrate this we have used mel-frequency cepstral coefficients (MFCC) and linear prediction cepstral coefficients (LPCC) as feature. Gaussian mixture model (GMM) and GMM-universal background model (GMM-UBM) are used for modeling the speaker. The database used is NIST-2003. The experimental results indicate that, improved performance of MFS, MFR, and MFSR analysis radically better compared with SFSR analysis. The experimental results show that LPCC based MFSR analysis perform better compared to other analysis techniques and feature extraction techniques.

• Safety and Health at Work
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• v.13 no.2
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• pp.180-186
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• 2022

Background: In occupational studies, it is a known situation that technical and organizational attempts are used to prevent occupational accidents. Especially in the mining sector, if these attempts cannot prevent occupational accidents, personal protective equipment (PPE) becomes a necessity. Thus, in this study, the main objective is to examine the effects of the variables on the use of PPE and identify important factors. Methods: A questionnaire was implemented and structural equation modeling was conducted to ascertain the significant factors affecting the PPE use of mining employees. The model includes the factors that ergonomics, the efficiency of PPE and employee training, and PPE usage habit. Results: The results indicate that ergonomics and employee training have no significant effect (p > 0.05) on the use of PPE. The efficiency of PPE has a statistically meaningful effect (p < 0.05) on the use of PPE. Various variables have been evaluated in previous studies. However, none of them examined the variables simultaneously. Conclusion: The developed model in the study enables to better focus on ergonomics and employee training in the PPE usage. The effectiveness of a PPE makes its use unavoidable. Emphasizing PPE effectiveness in OHS training and even showing them in practice will increase employees' PPE usage. The fact that a PPE with high effectiveness is also ergonomic means that it will be used at high rates by the employee.