• Journal of Korean Society of Steel Construction
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• v.28 no.3
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• pp.173-183
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• 2016

Various material characteristics of HSA800 steel were examined and a quantitative criteria about the homogeneity of the strength was proposed. Whether HSA800 steel is satisfied the criteria for homogeneity of the strength or not was also examined. From the test results, the material characteristics of 1/4 point from the extreme fiber in the Z-direction satisfied the KS requirements. The excellent directional properties and impact resistance at low temperatures were also showed from the test results. HSA800 steel satisfied the criteria of homogeneity for the strength of the steel. However, it showed that some structures were banded together at 2/4 point from extreme fiber in the Z-direction from the microscopic tests and attention is needed to be paid in that point.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.447-455
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• 2010

The objective of this study was to analyze the difference in kinematic variables for successful and unsuccessful golf putting strokes. The study population included 8 male secondary school golf players who had played golf for over 3 years and whose handicap was 4 or lower. A hole was made on a 5-m-long artificial flat mat for practice, and an environment similar to that of a real green was created. The participants' motions were analyzed through 3D image analysis, and the difference in kinematic variables for successful and unsuccessful putting strokes in the same direction was determined. Data analysis revealed the following findings: The time spent for a segment of putting was the greatest for the backswing segment for both successful and unsuccessful strokes. During address and impact, the both changed to a larger extent. For successful putting strokes, the change in the elbow angle during the downswing was greater for the right elbow than for the left elbow. For both successful and unsuccessful putting strokes, the left shoulder angle increased during the segment from address to the turning point and decreased during the segment from the turning point to impact. In contrast, the right shoulder angle significantly differed between successful and unsuccessful putting strokes only during address. During successful and unsuccessful motions, the swing was executed with the moving displacement of the X-axis of the club head maintained almost constant along a straight light without back and forth movement. In the backswing segment, moving displacement of the Y- and Z-axes was greater in successful strokes than in unsuccessful strokes; however, this difference was very small for the Y-axis. The velocity of the club head for successful and unsuccessful motions significantly differed during address and at the turning point. The highest velocity of the ball was greater for successful than for unsuccessful putting strokes.

• Advances in Energy Research
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• v.4 no.2
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• pp.121-146
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• 2016

This study is concerned with the analysis of two renewable technologies for electric energy production: wind energy and photovoltaic energy. The two technologies were assessed and compared by economic point of view, by using selected indicators characterized by a clear calculation approach, requirement of information easy to be collected, clear, but even complete, interpretation of results. The used economic indicators are Levelized Cost of Energy, $CO_2$ abatement cost and fossil fuel saving specific cost; these last two specifically aimed at evaluating the different capabilities that renewable technologies have to cut down direct $CO_2$ emissions and to avoid fossil fuel extraction. The two technologies were compared also from the environmental point of view by applying Life Cycle Assessment approach and using the environmental impact categories from the Eco-indicator'95 method. The economic analysis was developed by taking into account different energy system sizes and different geographic areas in order to compare different European conditions (Italy, Germany and Denmark) in term of renewable resource availability and market trend. The environmental analysis was developed comparing two particular types of PV and wind plants, respectively residential and micro-wind turbine, located in Italy. According to the three calculated economic indicators, the wind energy emerged as more favorable than PV energy. From the environmental point of view, both the technologies are able to provide savings for almost all the considered environmental impact categories. The proposed approach, based on the use of economic and environmental indicators may be useful in supporting the policies and the decision making procedures concerned with the promotion and use of renewables, in reference to the specific geographic, economic and temporal conditions.

• Atmosphere
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• v.33 no.5
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• pp.549-560
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• 2023

This study evaluates three distinct observation methods, CRDS, OA-ICOS, and OF-CEAS, in greenhouse gas monitoring equipment for atmospheric CO₂ and CH₄ concentrations. The assessment encompasses fundamental performance, high-concentration measurement accuracy, calibration methods, and the impact of atmospheric humidity on measurement accuracy. Results indicate that within a range of approximately 500 ppm, all three devices demonstrate high accuracy and linearity. However, beyond 1000 ppm, CO₂ accuracy sharply declines (84%), emphasizing the need for caution when interpreting high-concentration CO₂ data. An analysis of calibration methods reveals that both CO₂ and CH₄ measurements achieve high accuracy and linearity through 1-point calibration, suggesting that multi-point calibration is not imperative for precision. In dynamic atmospheric conditions with significant CO₂ and CH₄ concentration variations, a 1-point calibration suffices for reliable data (99% accuracy). The evaluation of humidity impact demonstrates that humidity removal devices significantly reduce air moisture levels, yet this has a negligible effect on dry CO₂ concentrations (less than 0.5% relative error). All three observation method instruments, which have integrated humidity correction to calculate dry CO₂ concentrations, exhibit minor sensitivity to humidity removal devices, implying that additional removal devices may not be essential. Consequently, this study offers valuable insights for comparing data from different measurement devices and provides crucial information to consider in the operation of monitoring sites.

• Advances in concrete construction
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• v.15 no.1
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• pp.23-39
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• 2023

One of the important problems of concrete placing is the concrete compaction, which can affect the strength, durability and apparent quality of the hardened concrete. Therefore, vibrating operations might be accompanied by much noise and the need for training the involved workers, while inappropriate functioning can result in many problems. One of the most important methods to solve these problems is to utilize self-compacting cementitious composites instead of the normal concrete. Due to their benefits of these new materials, such as high tensile, compressive, and flexural strength, have drawn the researchers' attention to this type of cementitious composite more than ever. In this experimental investigation, six mixing designs were selected as a base to acquire the best mechanical properties. Moreover, forty-eight rectangular composite panels with dimensions of 300 mm × 400 mm and two thickness values of 30 mm and 50 mm were cast and tested to compare the flexural and impact energy absorption. Steel fibers with volume fractions of 0%, 0.5% and 1% and with lengths of 25 mm and 50 mm were imposed in order to prepare the required cement composites. In this research, the composite panels with two thicknesses of 30 mm and 50 mm, classified into 12 different groups, were cast and tested under three-point flexural bending and repeated drop weight impact test, respectively. Also, the examination and comparison of flexural energy absorption with impact energy absorption were one of the other aims of this research. The obtained results showed that the addition of fibers of longer length improved the mechanical properties of specimens. On the other hand, the findings of the flexural and impact test on the self-compacting composite panels indicated a stronger influence of the long-length fibers.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.137-143
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• 2002

This paper concerns the spin-stabilization for the second stage of KSR-III(Korea Sounding Rocket-III). The error sources in the second stage are defined, and then the effect on attitude error of KSR-III is analyzed quantitatively and qualitatively. Based on the analysis, some conditions for optimal spinning frequency and optimal steady-spinning duration are suggested. Among several solutions, an optimal value can be determined in the point of minimum impact-point error. An approach to a sub-optimal solution is also suggested. Application to the KSR-III shows that a proper spinning frequency and a steady-spin duration to give the smallest impact-point error can be effectively determined.

• Journal of Information Technology Applications and Management
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• v.21 no.4
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• pp.157-171
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• 2014

As electronic word of mouth plays an important role in purchase behavior among consumers, the number of studies on the impact of electronic word of mouth is rapidly increasing. Nevertheless, it is difficult to discover comparative studies on the mass media which had a great impact on consumer's purchase behavior before the impact of electronic word of mouth becomes greater versus the social media where electronic words of mouth are created and distributed. It is considered that it seems to be necessary to find an appropriate mutual supplement point between the media designed for a successful marketing by comparing and analyzing the existing mass media versus the social media, major media for electronic word of mouth. Therefore, this study aims to compare and analyze the impact of comments on movie revenue in the representative forms of mass media such as online news and social media blogs. In particular, this study also considers an appropriate media for promoting movies by period by comparing and analyzing the two media before and after film release. For analysis, this study collects the information on the number of comments on online news and blogs in 70 Korean movies released in 2011 and 2012 from five weeks before film release to eight weeks after film release on a daily basis via Naver. This study also collects the information on the movie revenue using the statistical data of movie industry from Korean Film Commission. As a result of empirical data analysis, it is found that the two media showed no difference in movie revenue before film release, but after film release, the impact of blogs was more significant than that of online news.

• Korean Journal of Applied Biomechanics
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• v.34 no.1
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• pp.34-44
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• 2024

Objective: This study aimed to investigate how the movements occurring during the follow-through phase after releasing an arrow among elite compound archers, are associated with the arrow impact points on the target. Method: Nine elite archers performed consecutive compound archery shooting under conditions identical to actual competitions using their own bows and equipment. Motion capture system and force platform were utilized to record the changes in joint positions and center of pressure, respectively. Principal component analysis was employed to identify the patterns in which multidimensional joint positions and COP changes were organized with horizontal and vertical coordinates of arrow impact points. Subsequently, correlation analysis quantified the relationship between individual variables and the coordinates of arrow impacts on the target. Results: We found a common organizational pattern in which the two axes of the impact point coordinates were grouped into the first two principal components. The movements of the upper and lower limbs following release exhibited opposite patterns in the anterior-posterior axis, with significant correlations observed between the arrow impact points of the horizontal axis and the left shoulder, right elbow, left hip, and both knees. Additionally, the lateral movements induced by the reaction force upon arrow release showed significant associations with the vertical coordinates of the impact points. Particularly, the correlations between the movements of the left shoulder and elbow, as well as the bilateral hip and right knee, were consistently observed among all participants. Conclusion: These findings implied that the post-release movements could significantly influence the trajectory and impact points of the arrows in compound archery. We suggest that a consistent and controlled movement during the follow-through phase may be more beneficial for optimizing shooting accuracy and precision rather than minimizing movements.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.10
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• pp.813-820
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• 2021

In this study, a low-velocity impact test was performed to obtain the dynamic properties of solid propellants. The dynamic behavior of the solid propellant was examined by measuring the force and displacement of the impactor during the low-velocity impact test. The bending displacement was calculated by compensating for the local displacement caused by the low-velocity impact test in the form of three point bending and the shear displacement caused by using a short and thick solid propellant specimen. Stress and strain were calculated using compensated displacements and measured force, and dynamic properties of solid propellants were obtained from the stress-strain curve and compared with static bending test. The dynamic properties of solid propellant under the low-velocity impact loading at various operating temperature conditions such as room temperature(20 ℃), high temperature(63 ℃), and low temperature(-32 ℃) were compared and investigated.

• Spatial Information Research
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• v.20 no.1
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• pp.71-80
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• 2012

Carbon Point system is Climate Change Action Program by providing incentives in proportion to voluntary reduction of energy consumption such as electricity, gas and water for houses, commercial facilities. So far, existing researches have been limited to construction of GHG(Green House Gas) Inventory and have little attention to empirical impact analysis on carbon reduction policy regarding the residential section. Therefore, this paper is intended to provide convincing findings of impact analysis on carbon reduction, revolving around the carbon point system. For this, we firstly calculated the carbon emission by using electricity and gas usage data in household targeting to Seongbuk-Gu. Carrying out IPA and spatio-temporal analysis. Then, we are capable of visualizing spatial patterns from 2007 to 2009 as a macro analysis. Following that, we explored the effect on carbon point system through Ex ante-Ex post Analysis by paired t-test. To conclude, we can spatially identify the distribution with a significant difference between carbon emissions according to energy use as a micro analysis by Hot Spot to Analysis on point entities. It is to be hoped that this method will be utilized to establish various policies and to evaluate the effect of reduction of GHG.