• East Asian mathematical journal
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• v.30 no.4
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• pp.475-491
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• 2014

We can easily see the 'cycloid slide' in the many mathematics and science museums. The educational materials, however, do not give us any mathematical principle. For this reason, we, in this thesis, first study the brachistochrone problem in the history of mathematics, and suggest a method of how to teach the principle using 'the dynamic geometry software GSP5' in order to help students understand the idea that the cycloid is the brachistochrone. Secondly, we examine the origin of the calculus of variations and apply it to prove the brachistochrone problem in order to build up the teachers' background knowledge. This allows us to increase the worth of history of mathematics and recognize how useful the learning is which uses technological tools or materials, and we can expect that the learning which makes use of cycloid slide will be meaningful.

• Clinical Pain
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• v.19 no.2
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• pp.64-69
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• 2020

Ultrasound (US) imaging is an efficient, easy to use, rapid, dynamic, noninvasive, with rare side-effects and inexpensive tool allowing for facilitated diagnosis and management of the painful shoulder. It also has advantages over other imaging modalities in the evaluation of the postoperative shoulder for rotator cuff integrity and correct anchor and suture placement, as well as rotator cuff analysis following repair surgery. Early postoperative tendons frequently had a hypo- echoic echo texture and the absence of a fibrillar pattern, which might be misinterpreted as recurrent tears. however, these features often normalized into tendons with an increased echo texture and the reappearance of a fibrillar pattern at 6 months. Based on these sequential findings, the US findings within 3 months after surgery should be interpreted with caution to accurately understand and monitor the repaired tendon status.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.12
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• pp.1417-1426
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• 2009

Various types of damper are usually applied to reduce noise and vibration for mechanical systems. Especially, for washing machines, the free-friction stroke damper is installed. The behavior of the free-friction stroke damper has nonlinear characteristics such as hysteresis and viscoelastic properties because of its foam material. First of all, the dynamic experiments were carried out by using a MTS machine to find characteristics of the free-friction stroke damper. And the simulation model of the free-friction stroke damper and characteristics of a foam material were evaluated by using optimization technique. To make a good simulation model which can show the dynamic characteristics, it is important to understand the working mechanism of the damper. The Finite Element Method (FEM) technique can help us instinctively understand the damping phenomenon under operating conditions, because we can observe the condition of damper at every step in the simulation by using it. Also, by changing factors, we can comprehend the variation of characteristics of damper. So, in this paper, a study on the dynamic characteristics of free-friction stroke damper by FEM is focused on. Finally, the possibility which physical experiments can be replaced into simulations is shown.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2581-2588
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• 2000

In previous studies, the dynamic resistance, which was calculated by the process variables measured at the electrode of the welding machine, and the electrode displacement were used for quality exa mination. However, in-process usage of such systems is not effective in systems that include a welding gun attached to a robot. In order to overcome such problems, we obtained and used the process variables from the welding machine timer. This would allow us to estimate real time in -process weld quality. For quality estimation, the features were extracted as factors from the primary dynamic resistance patterns, which were measured in t he welding machine timer. The relationship between the indexes and nugget size of the welds was observed through the regression analysis. Using the analyzed factors, a regression model that could estimate nugget diameter was developed. Two regression equations of the model were suggested depending on the factors, and it was showed that the model developed by stepwise method was effective one for weld quality estimation. The developed estimation model was in good linearity with the nugget diameter obtained through the experimentation.

• Structural Engineering and Mechanics
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• v.58 no.1
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• pp.39-58
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• 2016

Since the publication of ACI 318-02, the concrete capacity design (CCD) method has been used to determine the resistance of unreinforced concrete anchors. The regulation of steel-reinforced anchors was proposed in ACI 318-08. Until ACI 318-08, the shear resistance of concrete breakout for an unreinforced anchor during an earthquake was reduced to 75% of the static shear strength, but this reduction has been eliminated since ACI 318-11. In addition, the resistance of a hairpin-reinforced anchor was calculated using only the strength of the steel, and a regulation on the dynamic strength was not given for reinforced anchors. In this study, shaking table tests were performed to evaluate the dynamic shear strength of unreinforced and hairpin-reinforced cast-in-place (CIP) anchors during earthquakes. The anchors used in this study were 30 mm in diameter, with edge distances of 150 mm and embedment depths of 240 mm. The diameter of the hairpin steel was 10 mm. Shaking table tests were carried out on two specimens using the artificial earthquake, based on the United States Nuclear Regulatory Commission (US NRC)'s Regulatory Guide 1.60, and the Northridge earthquake. The experimental results were compared to the current ACI 318 and ETAG 001 design codes.

• Journal of The Korean Association For Science Education
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• v.25 no.1
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• pp.41-56
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• 2005

Assessing students' knowledge can be a challenging endeavor, as researchers attempt to capture the full complexity and potential development of children's ideas. In this study, the Dynamic Science Assessment (DSA) method (Magnusson, Templin, and Boyle, 1997) was employed to investigate 9-12 year old students' understandings of light, while engaging in multiple tasks with a flashlight with various reflectors and mirrors. The results showed that DSA was effective in providing an opportunity to establish a Zone of Proximal Development, in addition to diagnosing a student's prior understanding. Throughout the interview, a student showed a conceptual model of light as being a solid single entity whose shape can be determined by the shape of the casing of a flashlight. However, as DSA provided phenomena that could not be explained by his unitary model, the student began to re-examine his original conceptual model, and attempted to revise it. This study addressed how Dynamic Science Assessment can help us better understand, not only students' current state of understanding, but also a potential development of understanding in their ZPD. In that sense, this study argues that we should pay more attention to the instructive role of classroom assessment that can promote and support further development of students' deeper understandings.

• The Journal of Korean Association of Computer Education
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• v.12 no.2
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• pp.13-22
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• 2009

In this paper, we propose a new dynamic syllabus composition system to solve the problems of a static syllabus which can appear in the field of computer education, where the relationship between pre-post study subjects is clear and teachers may grasp easily the degree of understanding of learners in real time. Our dynamic syllabus composition system is designed to be adjusted according to the physical change of the amount of education and the level of learners, which is based on the priority of educational objects. The result of instance performed on two groups of different entering behavior shows that the proposed method enhances the degree of transfer of education and helps us teach a class around the representative subject which has to be dealt with in the class, so that it is very effective for the achievement of educational objects prior to others.

• International Journal of Automotive Technology
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• v.4 no.3
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• pp.149-156
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• 2003

This paper is concerned with the energy absorption efficiency of auto-body side structures for the conventional steel and 60TRIP high strength steel. In order to evaluate the energy absorption efficiency, the dynamic crash analysis is carried out with the regulation of US-SINCAP. The analysis adopts the Johnson-Cook model for the dynamic material properties, which have been obtained from dynamic material tests. For the sake of the dynamic material properties, the analysis has been accurately peformed for the crashworthiness assesment. The analysis result provides deformed shapes, amounts of penetration and accelerations at several important points during crash. The result confirms that 60TRIP greatly improves the crashworthiness of the side members without sacrificing the weight and thus can be used for the light-weight design of an auto-body.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.2
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• pp.143-157
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• 2008

Ubiquitous Web Services is able to be specified future Web Services technology for connecting with various application services in any device and network environments. The devices, in ubiquitous environment, have dynamic characteristic such as location and statuse. So, we must support methods of dynamic service discovery in ad-hoc network. There are many related works at transaction, security, QoS, semantic and Web Services composition with various fields. Recently, the studies are interested in the Ubiquitous by development of computing and network technology. However, they are an early stage. For this reason, in this paper, we propose a WSUN(Web Services on Universal Networks) for Ubiquitous Web Services. It is a SOA based framework. And this paper extracts necessity of WSUN environment from scenario. The framework is composed of US Broker(Universal Service Broker). It is designed for satisfying the conditions and supports dynamic service discovery using a US Registry (Universal Service Registry). Consequently. clients are able to discover and use Universal Service by protocol stack of the US Broker for Web Services. And it is a strong point which supports interoperability between heterogeneous networks.

• Journal of the Korea Computer Graphics Society
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• v.2 no.1
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• pp.48-60
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• 1996

This paper present a new technique for doing realistic computer animation. The method is based on forward dynamic simulation and nonlinear problem solving (parameter optimization) technique. Objects are modelled physically and simulated faithfully while satisfying kinematic and geometric constraints. This forward dynamic simulation gives us very realistic motions especially for non-voluntary motions. Then we extend simulation technique to do animation using parameter optimization. The basic idea is to add motion control over the entire animation. The motion control is finding optimal solutions while satisfying user's animation goals. We provide two different animation technique; one is for rigid body without joint actuators and the other is for rigid body with linear joint actuators. To achieve motion control, we convert single simulation to single nonliner function evaluation while either setting initial conditions as variables for the function or allocating control variables in terms of time. This method is presented with two animation examples: dice-magic and human stand-up.