• Journal of Auto-vehicle Safety Association
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• v.11 no.4
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• pp.22-27
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• 2019

In this paper, the vibration load and analysis results for automotive battery supporter were performed to provide efficient vibration tolerance performance prediction methods for single-product vibration tolerance testing, and the major influencing factors and considerations for setting up single-unit vibration tolerance tests were reviewed. A common applicable standard load was applied to efficiently predict the performance of single-unit vibrations through the frequency response analysis technique. The results similar to test results can be predicted by checking vulnerable parts of the vehicle components for vibration loads and applying scale factor to standard loads. In addition, it was confirmed that the test conditions with a frequency generating the same durability severity as the endurance test are needed for accurate prediction of the durability of the single-unit vibration tolerance test conditions, and the acceleration and frequency with the conditions that there is no significant nonlinear phenomena in the vibration system are established during the single-unit vibration tolerance test conditions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.200-201
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• 2015

The unit modular method is one in which unit modules are prefabricated at a factory and then constructed at a construction site. That is why an important process, transporting unit module, is added in this method. The purpose of this study is to analyse the load for transporting unit module. The results of the analysis of the driving experimental runs revealed that a maximum load of 15 kN was applied on adapter block type A and a maximum load of 25 kN on adapter block type B. These loads were recorded at the points in the road test when the low-bed trailer was driving through unstable sections of the test such as stopping, restarting, passing over a speed bump or taking a left turn at speed.

• The Mathematical Education
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• v.57 no.1
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• pp.37-54
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• 2018

Despite the significance of fraction in elementary mathematics education, it is not easy to teach it meaningfully in connection with real life in Korea. This study aims to investigate and analyze 3rd grade students' understanding on unit fraction concepts and on comparison of unit fractions and to identify the parts which need to be supplemented in relation to unit fraction. For these purposes, I reviewed previous studies and extracted chapters which cover unit fractions in elementary mathematics textbooks based on 2009 revised curriculums and analyzed teaching contexts and visual representations of unit fractions. From this point of view, I constructed a test which consists of three problems based on Chval et al(2013) to investigate students' understanding on unit fraction. To apply this test, I selected forty-one 3rd grade students and examined that students' aspects of understanding on unit fraction. The results were analyzed both qualitatively and quantitatively. In this study, I present the analysis results and provide implications and some didactical suggestions for teaching contexts and visual representations of unit fraction based on the discussion.

• East Asian mathematical journal
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• v.30 no.4
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• pp.509-526
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• 2014

The mathematics has moved toward the independence from unit. However, is this tendency also kept up in teaching and learning mathematics? This study starts from this question. We have illuminated this question in respects of a character of unit operation, an essential probability of unit operation and a didactical application of unit. As results, addition and subtraction are operations on identical objects and the result of operation does not also get out of operation's object. On the other hand, multiplication and division are operations on both identical objects and different objects. And the result of operation can generate new unit. We proposed a hypothesis which multiplication and division are transcendental operations from this analysis. The unit operation is not possible essentially. It seems only like unit operation is possible superficially by operational definition on unit. We could discuss on a didactical application of unit from above analysis. And we could deduct implications that the direction of developing mathematic does not necessarily match with the direction of teaching and learning mathematics.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1207-1219
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• 2022

「Act On Contracts To Which The State Is A Party」 stipulates that the "Construction Standard Production Rate" and "Construction Standard Unit Price" be used as the criteria for determining the estimated price of construction works performed by public institutions. In this regard, issues such as the application scope of the Construction Standard Unit Price, and the effect of budget reduction continue. However, due to the lack of quantitative data on the actual application of Construction Standard Unit Price, it is difficult to objectively evaluate various issues. In order to prepare data for objective evaluation of the Construction Standard Unit Price, this study analyzed the ripple effect of applying the Construction Standard Unit Price based on the bill of quantity. As a result of the analysis, the Construction Standard Unit Price ripple effect in the civil engineering part was 9.2%, and it was analyzed that there was a ripple effect of about 1.9% based on the civil engineering direct cost. In the construction part, the ripple effect was analyzed to be relatively high at 17%, but it was found to have a ripple effect of about 3% in the construction direct cost. Based on the total direct cost, the ripple effect was calculated as 2.2%. Based on the analysis results, it is possible to evaluate the effect of applying the Standard Market Unit Price, and it is expected to be used as basic data to solve issues. As a future study, it is necessary to additionally analyze the ripple effect by Standard Market Unit Price application range (over 10 billion, over 20 billion won, etc.) and delivery system type (comprehensive evaluation, qualification examination, technical bidding, etc.). In addition, it is necessary to study the appropriate ripple effect of the Standard Market Unit Price.

• Journal of the Korea Fashion and Costume Design Association
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• v.18 no.2
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• pp.51-64
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• 2016

The object of this study was to find out the influence of juvenile self-consciousness on the importance of unit 'clothing and self-express' in technology home economics curriculum and appearance management behavior. Questionnaires were administered to 244 middle school students living in Deagu metropolitan City. Frequency, factor analysis, reliability analysis, regression analysis, and ${\chi}^2-test$ were used for data analysis. Our findings are as follows. Self-consciousness had factors as privately and socially self-consciousness and social anxiety. The factors of the importance of unit 'Clothing and self-express' were clothing, self-express and excellence in traditional clothing. Appearance management behavior had factors as appearance management, plastic surgery interest, diet importance, health focus and eating habit. Self-consciousness was found to have significant effects on the factors of the importance of unit 'Clothing and self-express', and self-consciousness on factors of appearance management behavior. The differences by gender of middle students was examined in clothing and textile interest, clothing and textile unit interest and knowledge acquisition route.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.446-451
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• 2011

Recent trends for the miniaturization and weight reduction of portable electronic parts have driven uses of subminiature components. Assembly of the miniaturized components requires subminiature screws of which pitch sizes are micrometer scale. To produce such subminiature screws with high precision threads, not only a precision forming technology but also a high-precision measurement technology is required. The present study covers the development of a vision inspection system for precision screws for the automatic measurement of subminiature screws with high speed and reliability. In this study, the feeding unit that transfers the subminiature screws to the inspection unit is investigated through finite element(FE) analysis. The vibration characteristics of the feeding unit are predicted through FE analyses, from which we can determine whether the subminiature screw can be stably fed into the inspection unit or not. The effects of several design parameters on the vibration characteristics are also discussed.

• Interaction and multiscale mechanics
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• v.3 no.3
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• pp.213-234
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• 2010

A multiscale method is presented for analysis of thin slab structures in which the microstructures can not be reduced to two-dimensional plane stress models and thus three dimensional treatment of microstructures is necessary. This method is based on the classical asymptotic expansion multiscale approach but with consideration of the special geometric characteristics of the slab structures. This is achieved via a special form of multiscale asymptotic expansion of displacement field. The expanded three dimensional displacement field only exhibits in-plane periodicity and the thickness dimension is in the global scale. Consequently by employing the multiscale asymptotic expansion approach the global macroscopic structural problem and the local microscopic unit cell problem are rationally set up. It is noted that the unit cell is subjected to the in-plane periodic boundary conditions as well as the traction free conditions on the out of plane surfaces of the unit cell. The variational formulation and finite element implementation of the unit cell problem are discussed in details. Thereafter the in-plane material response is systematically characterized via homogenization analysis of the proposed special unit cell problem for different microstructures and the reasoning of the present method is justified. Moreover the present multiscale analysis procedure is illustrated through a plane stress beam example.

• International journal of advanced smart convergence
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• v.12 no.3
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• pp.211-220
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• 2023

Surface electromyography (sEMG) is a noninvasive method used to capture electrically muscle activity, which can be easily measured even during exercise. The basic unit of muscle activity is the motor unit, and because an sEMG signal is a superposition of motor unit action potentials, analysis of muscle activity using sEMG should ideally be done from the perspective of motor unit activity. However, conventional techniques can only evaluate sEMG signals based on abstract signal features, such as root-mean-square (RMS) and mean-power-frequency (MPF), and cannot detect individual motor unit activities from an sEMG signal. On the other hand, needle EMG can only capture the activity of a few local motor units, making it extremely difficult to grasp the activity of the entire muscle. Therefore, in this study, a method to visualize the activities of motor units in a single-channel sEMG signal by relocating wavelet coefficients obtained by redundant discrete wavelet analysis is proposed. The information obtained through this method resides in between the information obtained through needle EMG and the information obtained through sEMG using conventional techniques.

• Computers and Concrete
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• v.8 no.5
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• pp.525-539
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• 2011

This paper describes the development of a fiber reinforced concrete (FRC) unit cell for analyzing concrete structures by executing a multiscale analysis procedure using the theory of homogenization. This was achieved through solving a periodic unit cell problem of the material in order to evaluate its macroscopic properties. Our research describes the creation of an FRC unit cell through the use of concrete paste generic information e.g. the percentage of aggregates, their distribution, and the percentage of fibers in the concrete. The algorithm presented manipulates the percentage and distribution of these aggregates along with fiber weight to create a finite element unit cell model of the FRC which can be used in a multiscale analysis of concrete structures.