• Earthquakes and Structures
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• v.9 no.4
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• pp.875-891
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• 2015

Earthquake can occur anywhere in the world and it is essential to design important members in special structures based on maximum possible forces that can be produced in them under severe earthquake. In addition, since the earthquake is an accidental phenomena and there are no similar earthquakes, therefore the possibility of strong earthquakes should be taken into account in earthquake-resistant design of important structures. Based on this viewpoint, finding the critical acceleration which maximizes internal forces is an essential factor in structural design. This paper proposes critical excitation method to compute the critical acceleration in design of important members in special structures. These critical accelerations are computed so that the columns' internal shear force at the base of the structure at each time step is maximized under constraints on ground motion. Among computed critical accelerations (of each time step), the one which produces maximum internal shear force is selected. A numerical example presents to show the efficiency of critical excitation method in determining the maximum internal shear force and base moment under variety of constraints. The results show that these method can be used to compute the resonant earthquake which have large enough effective duration of earthquake strong motion (between 12.86 sec to 13.38 sec) and produce the internal shear force and base moment for specific column greater than the same value for selected earthquakes in constructing the critical excitation (for different cases about 2.78 to 1.29 times the San Fernando earthquake). Therefore, a group of them can be utilized in developing the response spectrum for design of special structures.

• Journal of Korean Critical Care Nursing
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• v.11 no.2
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• pp.75-85
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• 2018

Purpose : The purpose of this study was to examine the possible direction of critical care nursing research in the future by analyzing the trends of recent Korean studies. Method : Using a database search, we selected 263 articles on critical care nursing that were published in Korean journals between 2008 and 2017. Then, we conducted an integrative review of the contents of the selected articles and analyzed the English abstracts using the relevant packages and functions of the R program. Results : The number of studies concerning critical care nursing has increased over the 10-year period, and the specific topic of each study has diversified according to the time at which it was conducted. In terms of quality, the majority of the research was published in high-level academic journals. The key words regularly studied over the past decade were: knowledge, delirium, education, restraint, stress, and infection. Studies related to vancomycin-resistant enterococci infection, compliance, and standards have decreased, while studies related to death, communication, and safety have increased. Conclusion : Randomized controlled trials and protocol research for evidence-based critical care need to be conducted, as does research on family involvement. The key word analysis of unstructured text used in this study is a relatively new method; it is suggested that this method be applied to various critical care nursing research and develop it methodologically.

• Journal of the Chungcheong Mathematical Society
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• v.16 no.1
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• pp.113-121
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• 2003

This paper is concerned with some properties of stable domains and limit functions. Using the relationship between cycles of periodic stable domains and orbits of critical points and using the Sullivan theorem [19], we prove that the value of a constant limit function in some stable domain for a rational function f of degree at least two lies in the closure of the set of critical orbits of f.

• Journal of Mechanical Science and Technology
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• v.18 no.4
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• pp.606-621
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• 2004

A dynamic analysis using a hybrid finite element method was performed to characterize the effects of a number of manufacturing errors on bearing forces and critical tooth stress in the elements of a planetary gear system. Some tolerance control guidelines for managing bearing forces and critical stress are deduced from the results. The carrier indexing error for the planet assembly and planet runout error are the most critical factors in reducing the planet bearing force and maximizing load sharing, as well as in reducing the critical stress.

• The KSFM Journal of Fluid Machinery
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• v.14 no.6
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• pp.91-95
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• 2011

This paper deals with the detail rotordynamic analysis for the assembly rotor composed of turbine wheel, turbine shaft, connecting arbor, and flange & spindle in order to perform the spin test of turbocharger turbine. Prior to rotordynamic analysis, the 1st spin test was performed but the test was failed by excess vibration in the neighborhood rated speed. It is the reason for this fail that the separation margin between the rated speed and critical speed is not enough, confirmed by rotordynamic analysis results. Since then, the dimension of turbine shaft was modified and the critical speeds were again reviewed for modified assmebly rotor. In results, the separation margin between the rated speed and critical speed is over 20% and then the 2nd spin test was performed successfully. In preparing spin test for turbine, compressor wheels and etc., the geometry design of connecting arbor and dimension of rough machining should be reviewed by considering rotordynamic results, and the separation margin should be enough for successful spin test.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.4
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• pp.43-50
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• 2006

The objective of this research is to select the most effective technique from AMT (Advanced Manufacturing Technologies) and IMP (Innovative Management Practices) for improving manufacturing performance in shipbuilding enterprises. The research consists of several principal steps. The first step is to design critical criteria in evaluating manufacturing performance in shipbuilding enterprises. The second step is to develop sub-criteria of the critical criteria. The third step is to develop a four level AHP (Analytic Hierarchy Process) structure using the critical criteria, sub-criteria and techniques from AMT and IMP. The fourth step is to develope the pairwise comparison matrix by each level of AHP structure, which was based on survey data collected at the H heavy industry. And the last step is to select the most effective technique from AMT and IMP by using AHP analysis. The results of AHP analysis did not show clear difference in priority between techniques of AMT and IMP in terms of manufacturing performance of the shipbuilding enterprise. Thus, each critical criterion was assigned modified weights and examined the priority change of techniques by conducting performance sensitivity analysis.

• Journal of Drive and Control
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• v.19 no.4
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• pp.1-9
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• 2022

The structure and operating principle of the 2-speed shift reducer were explained, the allowable bending stress value of the material was compared with the analysis result through FM structural analysis program, and the average stress distribution value of von Mises was performed on the gear root atmosphere. The structural safety of the 2-speed planetary gear reducer was verified through FM structural analysis. The natural frequency was calculated by applying the specifications of the planetary gears of the 2-speed gearbox, and the critical speed of resonance was calculated by calculating the natural frequency and the transmission error of the engaged gear pair. As a result of analyzing the critical speed, since it is formed higher than the actual operating speed range, it is considered safe because there is no resonance problem due to the suggested specifications of the planetary gears of the 2-speed shift reduction.

• Journal of Fisheries and Marine Sciences Education
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• v.19 no.2
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• pp.206-218
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• 2007

The purpose of this study was to investigate effects of critical thinking dispositions on vocational personalities in university students. Subjects were 111 University students in Busan. The questionnaire used in this research were Holland's Vocational Personality Questionnaire and California Critical Thinking Disposition Inventory. The results were analyzed by correlation analysis and enter multiple regression using the SPSS statistical package (SPSS for windows 12.0; SPSS Inc., Chicago, IL, USA). The study results were as follow: First, the students had much more S and R vocational personality characteristics than the others in vocational personality characteristics and had higher inquisitiveness and self-confidence scores than the others in critical thinking dispositions. Second, there were significant relationships between vocational personality types and critical thinking dispositions. Third, some of the vocational personality types were affected by the critical thinking dispositions. Especially I, E, and C personality of vocational personalities were prospected by critical thinking dispositions. Therefore, It's necessary that we understand the relationships between vocational personality types and critical thinking dispositions. Also we have to think over how to development career programs for university students to match to the learner's vocational personality type and critical thinking dispositions.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.834-841
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• 2022

System thermal-hydraulic (STH) code is adopted for nuclear safety analysis. The critical flow model (CFM) is significant for the accuracy of STH simulation. To overcome the defects of current CFMs (low precision or long calculation time), a CFM based on a genetic neural network (GNN) has been developed in this work. To build a powerful model, besides the critical mass flux, the critical pressure and critical quality were also considered in this model, which was seldom considered before. Comparing with the traditional homogeneous equilibrium model (HEM) and the Moody model, the GNN model can predict the critical mass flux with a higher accuracy (approximately 80% of results are within the ±20% error limit); comparing with the Leung model and the Shannak model for critical pressure prediction, the GNN model achieved the best results (more than 80% prediction results within the ±20% error limit). For the critical quality, similar precision is achieved. The GNN-based CFM in this work is meaningful for the STH code CFM development.

• The Korean Journal of Emergency Medical Services
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• v.12 no.3
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• pp.115-127
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• 2008

Purpose : This study aimed to examine the effects of empowerment of the paramedics on critical thinking and provide the basic materials for the qualitative improvement of emergency medical service. Methods : This study collected data with the paramedics working at general hospital and hospital emergency room in G metropolitan city, B metropolitan city, U metropolitan city, D metropolitan city and J province from July 1 to 31, 2008. Total 180 questionnaires were collected and 152 were used for final analysis, and the following results were obtained through statistical analysis using SPSS 12.0 program. Results : 1) Average score of empowerment was 4.44 out of 6 and according to average score by areas, significance was 4.94, capacity 4.92, self-determination 4.28, and effective-ness 3.62. 2) Empowerment by general characteristics was statistically significant in age (F = 3.313, p < 0.05), the final scholastic attainments(F = 2.436, p < 0.05), and salary(F = 1.695, p < 0.01). 3) Average score of critical thinking was 3.12 out of 7 and according to scores by areas, maturity was highest as 3.71, followed by no prejudice as 3.70, systemicity as 3.14, pursuit of truth as 3.05, much curiosity as 2.93, critical thinking and self-confidence as 2.92, and analysis as 2.91. 4) Critical thinking by general characteristics was statistically significant in marital status (F = 15.695, p < 0.01) and the final scholastic attainments (F = 2.606, p < 0.05). 5) Correlations between empowerment and critical thinking showed positive correlations as Pearson's correlation coefficient r = 0.400 and positive correlation in all areas including empowerment and critical thinking were found (r = 0.116-0.710). 6) The effect of empowerment on critical thinking was statistically significant in p < 0.01 and was explained as $R^2=0.155$. In the effects of empowerment on critical thinking, significance, capacity and self-determination were statistically significant in p < 0.01, effectiveness in p < 0.05 and were explained as R2 = 0.244. Conclusion : From the above results, it was found that empowerment had the influence on critical thinking, so it was considered that hospital managers and emergency room chiefs must develop and operate education and training program based on the concept of empowerment, maintenance and management strategies.