• Journal of Intelligence and Information Systems
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• v.27 no.2
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• pp.33-54
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• 2021

With the fourth industrial revolution and the arrival of the New Normal era due to Corona, the importance of Non-contact technologies such as artificial intelligence and big data research has been increasing. Convergent research is being conducted in earnest to keep up with these research trends, but not many studies have been conducted in the area of nuclear research using artificial intelligence and big data-related technologies such as natural language processing and text mining analysis. This study was conducted to confirm the applicability of data science analysis techniques to the field of nuclear research. Furthermore, the study of identifying trends in nuclear spent fuel recognition is critical in terms of being able to determine directions to nuclear industry policies and respond in advance to changes in industrial policies. For those reasons, this study conducted a media trend analysis of pyroprocessing, a spent nuclear fuel treatment technology. We objectively analyze changes in media perception of spent nuclear fuel dry treatment techniques by applying text mining analysis techniques. Text data specializing in Naver's web news articles, including the keywords "Pyroprocessing" and "Sodium Cooled Reactor," were collected through Python code to identify changes in perception over time. The analysis period was set from 2007 to 2020, when the first article was published, and detailed and multi-layered analysis of text data was carried out through analysis methods such as word cloud writing based on frequency analysis, TF-IDF and degree centrality calculation. Analysis of the frequency of the keyword showed that there was a change in media perception of spent nuclear fuel dry treatment technology in the mid-2010s, which was influenced by the Gyeongju earthquake in 2016 and the implementation of the new government's energy conversion policy in 2017. Therefore, trend analysis was conducted based on the corresponding time period, and word frequency analysis, TF-IDF, degree centrality values, and semantic network graphs were derived. Studies show that before the 2010s, media perception of spent nuclear fuel dry treatment technology was diplomatic and positive. However, over time, the frequency of keywords such as "safety", "reexamination", "disposal", and "disassembly" has increased, indicating that the sustainability of spent nuclear fuel dry treatment technology is being seriously considered. It was confirmed that social awareness also changed as spent nuclear fuel dry treatment technology, which was recognized as a political and diplomatic technology, became ambiguous due to changes in domestic policy. This means that domestic policy changes such as nuclear power policy have a greater impact on media perceptions than issues of "spent nuclear fuel processing technology" itself. This seems to be because nuclear policy is a socially more discussed and public-friendly topic than spent nuclear fuel. Therefore, in order to improve social awareness of spent nuclear fuel processing technology, it would be necessary to provide sufficient information about this, and linking it to nuclear policy issues would also be a good idea. In addition, the study highlighted the importance of social science research in nuclear power. It is necessary to apply the social sciences sector widely to the nuclear engineering sector, and considering national policy changes, we could confirm that the nuclear industry would be sustainable. However, this study has limitations that it has applied big data analysis methods only to detailed research areas such as "Pyroprocessing," a spent nuclear fuel dry processing technology. Furthermore, there was no clear basis for the cause of the change in social perception, and only news articles were analyzed to determine social perception. Considering future comments, it is expected that more reliable results will be produced and efficiently used in the field of nuclear policy research if a media trend analysis study on nuclear power is conducted. Recently, the development of uncontact-related technologies such as artificial intelligence and big data research is accelerating in the wake of the recent arrival of the New Normal era caused by corona. Convergence research is being conducted in earnest in various research fields to follow these research trends, but not many studies have been conducted in the nuclear field with artificial intelligence and big data-related technologies such as natural language processing and text mining analysis. The academic significance of this study is that it was possible to confirm the applicability of data science analysis technology in the field of nuclear research. Furthermore, due to the impact of current government energy policies such as nuclear power plant reductions, re-evaluation of spent fuel treatment technology research is undertaken, and key keyword analysis in the field can contribute to future research orientation. It is important to consider the views of others outside, not just the safety technology and engineering integrity of nuclear power, and further reconsider whether it is appropriate to discuss nuclear engineering technology internally. In addition, if multidisciplinary research on nuclear power is carried out, reasonable alternatives can be prepared to maintain the nuclear industry.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.992-1001
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• 2023

OWEC (Overtopping Wave Energy Converter) is a wave power generation system using the wave overtopping. The performance and safety of the OWEC are affected by wave characteristics, such as wave height, period. To mitigate this issue, optimal OWEC designs based on wave characteristics must be investigated. In this study, the environmental conditions along the Ulleungdo coast were used. The hydraulic efficiency of the OWEC was calculated using SPH (Smoothed Particle Hydrodynamics) by comparing 4 models that changed the substructure. As a result, it was possible to change the substructure. Through design optimization, a new truss-type structure, which is a substructure capable of carrying the design load, was proposed. Through a case study using member diameter and thickness as design variables, structural safety was secured under allowable stress conditions. Considering wave load, the natural frequency of the proposed structure was compared with the wave period of the relevant sea area. Harmonic response analysis was performed using wave with a 1-year return period as the load. The proposed substructure had a reduced response magnitude at the same exciting force, and achieved weight reduction of more than 32%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.737-742
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• 2017

Recently, unconventional high-rise building shapes have attracted attention as a landmark of metropolitan cities and the search for innovative building forms in architecture is ongoing. In this study, $Isotruss^{(R)}$ grid(ITG) used in smaller scale structures was applied to building structural systems and its structural performance was examined. The structural behavior of an ITG was compared with that of a diagrid structure as a reference structure. The stiffness-based design method of the diagrid system was used for the preliminary design stage of member sizing in an ITG. The structural design of 16, 32, and 48-story buildings was carried out for the two systems with the same size. The angle of the inclined columns for ITG and diagrid was $59^{\circ}$ and $68.2^{\circ}$, respectively. The lateral stiffness, steel tonnage of the exterior frame, axial strength ratio, story drift ratio, and natural frequency of the two systems were compared. Based on the analysis result of 6 buildings, the two systems had similar structural capacity; 93.3% and 88.7% of the lateral load was carried by the perimeter frame in the ITG system and diagrid system, respectively. This suggests that the ITG system is better in arranging core columns. Therefore, the proposed ITG system has not only a unique façade, but also substantial structural capacity equivalent to the existing system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.27-37
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• 1983

A method of dynamic analysis is developed for torsional free vibrations of elliptical-box girder type or stiffening truss system suspension bridge. In this study, the method based on a finite element technique using a digital computer, is illustrated by two numerical examples, the Namhae Bridge which is located in Kyungsang nam-do opened on June, 1973, and the Mt. Chunma Bridge is simple span pedestrian's suspension bridge with lateral bracing system in Mt. Chunma, Kyungki-do, are used. In general, dynamic modes of complex suspension bridges are three-dimensional in form, i.e., coupling between vertical and torsional motions. However, introduced that amplitudes of oscillation are infinitesimal for coincidence with the purpose of it's use, thereupon, the torsional vibration analyses are treated without coupling terms. A sufficient number of natural frequencies and mode shapes for torsional free vibration are presented in this paper. In the case of Mt. Chunma Bridge, the natural frequencies and periods are computed with and without reinforcement, respectively, and compared their discrepancies. The influence of the auxiliary reinforcing cables is prevailing in the first few modes, namely, 1st and 2nd in symmetric and 1st, 2nd and 3rd in antisymmetric vibration, and conspicuous in the symmetric compared with the antisymmetric motion, but in the higher modes, this kind of simple accessory elucidates rether converse effects. In the Namhae Bridge, the results are compared with the Manual's obtained by wind tunnel test. It reveals commendable agreement.

• Tribology and Lubricants
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• v.35 no.1
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• pp.44-51
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• 2019

The paper presents the rotordynamic performance measurements and model predictions of a fuel cell electric vehicle (FCEV) air compressor supported on gas foil bearings (GFBs). The rotor has an impeller on one end and a thrust runner on the other end. The front (impeller side) and rear (thrust side) gas foil journal bearings (GFJBs) are located between the impeller and thrust runner to support the radial loads, and a pair of gas foil thrust bearings are located on both sides of the thrust runner to support the axial loads. The test GFJBs have a partial arc shim foil installed between the top foil and bump strip layers to enhance hydrodynamic pressure generation. During the rotordynamic performance tests, two sets of orthogonally installed eddy-current displacement sensors measure the rotor radial motions at the rotor impeller and thrust ends. A series of speed-up and coast-down tests to 100k rpm demonstrates the dominant synchronous (1X) rotor responses to imbalance masses without noticeable subsynchronous motions, which indicates a rotordynamically stable rotor-GFB system. Finite element analysis of the rotor determines the rotor free-free (bending) natural modes and frequencies well beyond the maximum rotating frequency. The predicted damped natural frequencies and damping ratios of the rotor-GFB system reveal rotordynamic stability over the speeds of interest. The imbalance response predictions show that the predicted critical speeds and rotor amplitudes strongly agree with the test measurements, thus validating the developed rotordynamic model.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.2
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• pp.65-75
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• 2018

This study analyzes the characteristics of the urban landscape changes as a result of the introduction of private parks among the long-term uncollected urban planning facilities and enables the analysis of the characteristics of the urban landscape changes as a result of the introduction of private parks, and applied to the private park projects. The DSM with its building was established for the quantitative landscape analysis to examine the view ratio using the stacked visible analysis. The analysis showed that Jikdong Park had a high frequency of view from downtown to green due to its location, and that the development project of a private park on park and town boundaries significantly lowered the view ratio. This implies a large degree of damage to the landscape by development projects provided protection of the view as a natural landscape is of value. Chudong Park also saw its view ratio of views from downtown to the hills green area of Chudong Park was much lower than that of Jikdong Park. And it was confirmed that the ratio of view changes due to development projects was small compared to that of Jikdong Park. In other words, although Jikdong Park and Chu-dong Park were developed in a similar scale in terms of the ratio of views, they were subject to significant damage due to their location characteristics. It is also meaningful to note that the degree of change in the landscape resulting from development projects that could not be found in the assessment or review of the existing Landscape Impact. As private parks are introduced in the urban green belt, apartment development is being pushed for at the edge of the green belt. This study is meaningful in that it is derived based on the calculation that the survey results are derived based on the changes in the views on green areas that urban residents may experience as the private park project is carried out, and it should be introduced based on the calculation of the private parks.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.5
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• pp.45-54
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• 2007

Time/frequency analysis has been extensively used in biomedical signal processing. By extracting some essential features from the electro-physiological signals, these methods are able to determine the clinical pathology mechanisms of some diseases. However, this method assumes that the signal should be stationary, which limits its application in non-stationary system. In this paper, we develop a new signal processing method using Hilbert-Huang Transform to perform analysis of the nonlinear and non-stationary ventricular fibrillation(VF). Hilbert-Huang Transform combines two major analytical theories: Empirical Mode Decomposition(EMD) and the Hilbert Transform. Hilbert-Huang Transform can be used to decompose natural data into independent Intrinsic Mode Functions using the theories of EMD. Furthermore, Hilbert-Huang Transform employs Hilbert Transform to determine instantaneous frequency and amplitude, and therefore can be used to accurately describe the local behavior of signals. This paper studied for Return Of Spontaneous Circulation(ROSC) and non-ROSC prediction performance by Support Vector Machine and three parameters(EMD-IF, EMD-FFT) extracted from ventricular fibrillation ECG waveform using Hilbert-Huang transform. On the average results of sensitivity and specificity were 87.35% and 76.88% respectively. Hilbert-Huang Transform shows that it enables us to predict the ROSC of VF more precisely.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.24 no.2
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• pp.107-111
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• 2013

Objectives : We developed two-dimensional (2D) scanning videokyomography to evaluate the mucosal wave of whole vocal cords in real time to overcome the limit of preexisting stroboscopy and line scanning videokymography which could not evaluate it. Methods : We implemented a continuous light source with high brightness, a high-definition CMOS camera, and capture board for saving the data. We created the software program to analyze the image data from the system. The test of the functionality of the 2D scanning videokymography camera was performed in one of the authors (P.H.J 32 years old male). Vocal cord images were obtained during normal phonation and falsetto phonation. Images were obtained also during cough, diplophonia. Results : The system made it possible to measure objective parameters, including fundamental frequency, amplitude, regularity, mucosal wave, and phase difference, medial and lateral peak, opening versus closing duration related to vocal fold vibration. Simultaneously, it enabled analysis of the whole mucosal wave of the entire vocal fold in real time. 2D scanning videokymography was also effective for evaluating the dynamic status of the vocal fold when the subject phonated aperiodic voice. Conclusion : In conclusion, 2D scanning videokymography can support the analysis of the whole mucosal wave of the entire vocal cord with objective vocal parameters, overcoming the limitations of stroboscopy and previous line scanning videokymography techniques.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.53-62
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• 2006

Structural measurements obtained from accelerometers, strain gauges. and tilt meters at Ieodo ocean research station was analyzed. In the acceleration signals, dynamic characteristics of the station were round by using the measured dynamic responses under different wave attacks and were compared with those by numerical analysis. Data from strain gauges and tilt-meters were also analyzed to identify the present state of dynamic response. Effect of wave height on the dynamic characteristics were investigated. The present results and those which will be measured and analyzed later can be used to identify and to assess the state of the station whether it is health or not.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.654-664
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• 2011

A field campaign of magnetotelluric (MT) and audio-frequency MT (AMT) survey was done at 36 measurement points as a complementary for the previous 44 MT measurements completed during the period of 2005-2006. The purpose of additional MT survey is to investigate the possible fracture system in Seokmo Island, which is conceived to be crucial in accumulation and migration of geothermal hot spring in this area. We have done 2D and 3D inversions of overall MT and AMT data distributed on a grid to interpret subsurface of extended area. The inversion results reveal that at least two major faults are imaged in the inversion results, one of which is in NNE-SWW with steep dip, and another is in E-W direction.