• Transactions of Materials Processing
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• v.33 no.2
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• pp.112-117
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• 2024

In this study, the friction and wear characteristics of Inconel 600 in the superplastic forming process of Ti6Al4V were evaluated through pin-on-disc tests. To achieve an efficient and systematic experimental design, the Taguchi method was employed. The wear track of the Inconel 600 pin showed scratches in the sliding contact direction, confirming that the wear mechanism is abrasive wear. Through sensitivity analysis such as ANOVA and Main effects, it was confirmed that both normal force and sliding distance have a significant impact on the wear. Changes in sliding velocity and distance did not affect the friction coefficient, which remained relatively constant at approximately 0.380. The wear prediction model for Inconel 600 in the superplastic forming of Ti6Al4V was constructed, which can be utilized as a guideline for the prediction and management of tool wear.

• Journal of Korean Society for Quality Management
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• v.51 no.4
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• pp.677-689
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• 2023

Purpose: The purpose of this study is to design a x-ray screening rating system to improve X-ray screening ability, which is a core job competency of security screener at Incheon International Airport, and to verify its effectiveness through empirical analysis to suggest ways to improve the level management system. Methods: In this study, the effectiveness of the research model was analyzed using T-test tests for effect analysis based on the empirical analysis results derived through the competency evaluation model, the screening rating system. Results: The results of this study are as follows. The average score for regular education before the implementation of the x-ray screening rating system was 94.1 points, but after the implementation of the x-ray screening rating system, the average score for regular education was 95.5 points, an average of 1.4 points increased. In addition, the proportion of those with 95 or more points classified as high scorers also increased significantly from 51.1% to 69.3%. Conclusion: The X-ray screening rating system of security inspectors will systematically manage the level of screening ability, which is a key job competency, and play a strong role in improving competency, while preventing security accidents through early identification and intensive training of level-lowers.

• 대한공업교육학회지
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• v.38 no.2
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• pp.156-175
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• 2013

The purpose of this study was to verify that the impacts of experience of donation for education to improve the teaching efficacy of pre-technology teacher. The Invention experience of donation for education was performed with Invent-touring sponsored by Chunnam National University Invention Education Center for Teachers and was included by development of creative problem solving program, program execution and evaluation. Research participants were Technology education Majors and minors 20 students. The active locations were D children community center, K alternative school, D Elementary School and D middle school. For the study, various literature researches were reviewed intensively about donation for education and teaching efficacy. The instrument for the study was the modified STEBI(Science Teaching Efficacy Beliefs Instrument) for technology education by 3 experts. This study was designed by single group pre and post test design (One-Group Pretest-Posttest Design) and was conducted by the pre-test and post-test. Check the reliability of the tool was conducted with Cronbach ${\alpha}$ coefficient analysis, pre-test 0.840, post-test 0.746. The analysis of data from the 5% significance level, paired sample t-test was performed using the SPSS 19.0 statistical tool. The results were as follows: 1. Teaching efficacy of pre-technology teachers who participated in the invention experience for educational donation technology has improved. 72. The qualitative study was performed by the interviews with students who participated in. Humanism was positively change and learning opportunity was provided to develop the competence of technology education teacher. Based upon the conclusion of this study, the donation activity for invention education need to use learning strategies for pre-technology teacher to improve teaching efficacy.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.6
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• pp.851-858
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• 2018

Objective: This study was conducted to compare different methods on effective energy evaluation of corn silage for beef cattle. Methods: Twenty Wandong bulls (Chinese indigenous yellow cattle) with initial body weight of $281{\pm}15.6kg$, were assigned to 1 of 5 dietary treatments with 4 animals per treatment in a randomized complete block design. Five dietary treatments included group 1 with corn silage only diet, group 2 with corn silage-concentrate basal diet (BD) and 3 groups with 3 test diets, which were the BD partly substituted by corn silage at 10%, 30%, and 60%. The total collection digestion trial was conducted for 5 d for each block after a 10-d adaptation period, and then an open-circuit respiratory cage was used to measure the gas exchange of each animal in a consecutive 4-d period. Results: The direct method-derived metabolizable energy and net energy of corn silage were 8.86 and 5.15 MJ/kg dry matter (DM), expressed as net energy requirement for maintenance and gain were 5.28 and 2.90 MJ/kg DM, respectively; the corresponding regression method-derived estimates were 8.96, 5.34, 5.37, and 2.98 MJ/kg DM, respectively. The direct method-derived estimates were not different (p>0.05) from those obtained using the regression method. Using substitution method, the nutrient apparent digestibility and effective energy values of corn silage varied with the increased corn silage substitution ratio (p<0.05). In addition, the corn silage estimates at the substitution ratio of 30% were similar to those estimated by direct and regression methods. Conclusion: In determining the energy value of corn silage using substitution method, there was a discrepancy between different substitution ratios, and the substitution ratio of 30% was more appropriate than 10% or 60% in the current study. The regression method based on multiple point substitution was more appropriate than single point substitution on energy evaluation of feedstuffs for beef cattle.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.119-133
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• 2020

Underground utility tunnel, the most representative cut and cover structure, is subjected to seismic force by displacement of the surrounding soil. In 2020, Korea Infrastructure Safety Corporation has published "Seismic Performance Evaluation Guideline for Existing Utility Tunnel." This paper introduces two seismic evaluation methods, RDM (Response Displacement Method) and RHA (Response History Analysis) adopted in the guide and compares the methods for an example of an existing utility tunnel. The test tunnel had been constructed in 1988 and seismic design was not considered. RDM is performed by single and double cosine methods based on the velocity response spectrum at the base rock. RHA is performed by finite difference analysis that is able to consider nonlinear behavior of soil and structure together in two-dimensional plane strain condition. The utility tunnel shows elastic behavior for RDM, but shows plastic hinge for RHA under the collapse prevention level earthquake.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.208-215
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• 2021

In this study, a customiz ed bridge system was developed for North Korea application. For the application of North Korea, the customized bridge system design, fabrication, and construction performance evaluation were performed using ultra-high performance concrete a compressive strength 120MPa or more and a direct tensile strength 7MPa or more. The comparison of the North Korean truck luggage load(30, 40, 55) and the Korean standard KL-510 load showed that cross-section increased as the load increased. Furthermore, a bridge with a span length of 30m was fabricated with ultra-high performance concrete for the construction performance evaluation. The evaluation of the load condition analysis was performed by a flexural test. The results showed that a bridge with a span length of 30m secured about 167% of sectional performance under initial cracking load conditions and about 134% of load bearing capacity under ultimate load conditions. As a result of economic analysis, the customized bridge system using ultra-high-performance concrete was less than about 11% of the upper construction cost compared to the steel composite girder bridge. Therefore, these results suggest that the price competitiveness can be secured when applying the ultra-high-performance concrete long-span bridge developed through this study.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.561-568
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• 2021

In this study, in order to observe the change in the amount of Tire and Road Wear Particles and the ratio of tire components in it according to the tire wear resistance performance, carried out the evaluation by varying the vulcanization reaction design of the tire tread rubber. In addition, in order to improve the reliability of the evaluation of Tire and Road Wear Particles, the evaluation was performed indoor laboratory test equipment that simulates the condition on real driving to exclude various environmental influences including minerals, driver's habits, road surface, weather, tire structure and pattern designs. After the evaluation in closed space, it is estimated that the amount of collected Tire and Road Wear Particles is 84% compared to 100% of the tire and road wear loss weight, of which 96.4~97.7% was around the road and 2.3~3.6% was in the air. As a result of analy sis of the collected Tire and Road Wear particles, the tire component existed 63~75% in the Tire and Road Wear Particles depending on the wear resistance performance of the tire.

• Journal of the Korean Geotechnical Society
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• v.28 no.10
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• pp.5-16
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• 2012

Geotechnical buried structures with relatively light weight have been suffering from uplift damage due to liquefaction in the past earthquakes. The factor of safety approach by Koseki et al. (1997a), which is widely used in seismic design, predicts the triggering of uplift. However, a method for "quantitative" estimates of the uplift displacement has yet to be established. Estimation of the uplift displacement may be an important factor to be considered for designing underground structures under the framework of performance-based design (ISO23469, 2005). Therefore, evaluation of the uplift displacement of buried structure in liquefied ground during earthquakes is needed for a performance-based design as a practical application. In order to predict the uplift displacement quantitatively, a simplified method is derived based on the equilibrium of vertical forces acting on buried structures in backfill during earthquakes (Tobita et al., 2012). The method is verified through comparisons with results of centrifuge model tests and damaged sewerage systems after the 2004 Niigata-ken Chuetsu, Japan, earthquake. The proposed flow diagram for performance-based design includes estimation of the uplift displacement as well as liquefaction limit of backfill.

• Physical Therapy Rehabilitation Science
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• v.2 no.2
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• pp.99-103
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• 2013

Objective: Clinical measures that quantify upper extremity function are needed for the accurate evaluation of patients and to plan an intervention strategy. The purpose of this study was to examine the relationship between the Unified Parkinson's Disease Rating Scale (UPDRS)-Motor Exam and upper extremity performance as a quantifying clinical tool of upper extremity function in persons with Parkinson's disease. Design: Cross-sectional study. Methods: Thirty-two idiopathic Parkinson's Disease persons participated in this study. To investigate the relationship between the UPDRS-motor exam, Box and Block test (BBT), and Action Research Arm Test (ARAT) by two physical therapists. The examination took up to 1 hour, and the participants were invited to rest between each clinical measure in order to minimize the effects of fatigue. Clinical measures were assessed while the subjects were in the "on" phase of their medication cycle, generally 1-3 hour after taking their anti-Parkinson's medications. Results: In more affected side, the UPDRS-motor exam was significantly negative correlated with the BBT (p<0.05) but it was not significantly correlated with the ARAT. In less affected side, only positively correlation was significantly shown between BBT and ARAT (p<0.05). On the other hand, between BBT and ARAT were not significantly correlated with the UPDRS-motor exam. Conclusions: The UPDRS-motor exam is effective tool which was significantly correlated with manual dexterity in more affected upper extremity. But The UPDRS-motor exam is not effective tool in less affected upper extremity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.383-389
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• 2011

At the design stage, it is very important to know the ship maneuvering characteristics from the view point of ship performance and for the safety of navigation. IMO only gives some criteria for ships in full load even keel condition. However, the ship generally is operated not only in full load condition but also in half load condition or ballast condition. Therefore we must estimate the ship maneuvering in different loading condition to ensure that the ship will satisfy with IMO rules and navigate safely in every condition. In this paper, we have investigated the maneuvering characteristics of a ship by simulation and experiments with real ship. By comparing with the results of simulation, the real ship tests conform with simulation test and previous researches. Therefore, the method base on real data is well done to estimate the ship maneuvering in different loading conditions. The change of ship's manoeuverability accoriding to ship's operation conditions was estimated.