• Journal of Magnetics
• /
• v.18 no.3
• /
• pp.283-288
• /
• 2013

This paper presents structural topology optimization that is being applied for the design of electromagnetic vibration energy harvester. The design goal is to maximize the root-mean-square value of output voltage generated by external vibration leading structures. To calculate the output voltage, the magnetic field analysis is performed by using the finite element method, and the obtained magnetic flux linkage is interpolated by using Lagrange polynomials. To achieve the design goal, permanent magnet is designed by using topology optimization. The analytical design sensitivity is derived from the adjoint variable method, and the formulated optimization problem is solved through the method of moving asymptotes (MMA). As optimization results, the optimal location and shape of the permanent magnet are provided when the magnetization direction is fixed. In addition, the optimization results including the design of magnetization direction are provided.

• Wind and Structures
• /
• v.4 no.3
• /
• pp.247-260
• /
• 2001

In the last three decades several comprehensive field measurement programs have produced significant insight into the wind effects on low-rise structures. The most notable and well published of these efforts are measurements being collected at the Wind Engineering Field Laboratory (WERFL) at Texas Tech University, measurements on low-rise structures in Silsoe, England and measurements on groups of low-rise structures collected in Aylesbury, England. Complementary to these efforts, an additional full-scale field investigation program has recently collected meteorological, pressure, strain and displacement data on a low-rise structure in Southern Shores, North Carolina. To date over seventy-five hundred data sets have been collected at the Southern Shores site in a variety meteorological conditions up to and including hurricane-force winds. This paper provides details of the system, its development, and preliminary assessment of its performance. A description of the field site, the instrumented structure, and the instrumentation system is provided. In addition, an example of the data collected during three hurricanes is presented. The primary goal of this paper is to provide the reader with the necessary technical details to appropriately interpret data from this experiment, which will be presented in future publications currently under development.

• PNF and Movement
• /
• v.12 no.2
• /
• pp.81-88
• /
• 2014

Purpose: The purpose of this study is to examine the needs of prior field learning and the academic achievement of field experience learning in a college. Methods: This study was performed from May 1 to October 30, and students were given questionnaire. The research questionnaire as follows: (1) to investigate the academic achievement after field experience learning, (2) to verify the needs of field experience learning. A statistical analysis was performed using SPSS 17.0 for window version. Results: The results was as follows : First, satisfaction of field learning had scored good(47.2%) in lesson goal, good(51.8%) in acquisition of knowledge and techniques, good(51.0%) in preparation of study and good(45.9%) in association. Second, curriculum of field learning had scored normal(35.5%) in prior education, good(47.4%) in composition, good(50.8%) in guidance and good(47.2%) in contents. Third, curriculum of field learning had scored good(44.6%) in duration, good(46.1%) in numbers, good(51.3%) in convenience and normal(38.1%) in means of transportation. Forth, needs of field learning had scored good(46.6%) in field learning of practicum, good(48.2%) in field learning of theory subject, 3-4 times(42.0%) in frequency of field learning and 2hours(57.3%) in a field learning hour. Conclusion: These findings suggest that college student's thinking of field experience learning is positive. Field experience learning provided that college students have directly an opportunity of gaining valuable experience to feel the field.

• Journal of The Korean Association For Science Education
• /
• v.25 no.7
• /
• pp.728-735
• /
• 2005

In this study, relationships between student the cognitive affective characteristics and conceptual understanding from individual computer-assisted instruction were investigated. Tests regarding field dependence-independence, learning strategy, self-regulated ability, visual learning preference, goal orientation, self-efficacy on ability, and computer attitude were administered. After having been taught by means of a CAl program, a conception test on molecular motion was administered. It was found that student conceptual understanding was significantly related to field independence, learning strategy, self-regulated ability among the cognitive characteristics and visual learning preference, goal orientation, self-efficacy on ability among the affective characteristics. Multiple regression analysis of the cognitive characteristics on conceptual understanding found that field dependence-independence was the most significant predictor. Self-regulated ability and a deep learning strategy were also found to have predictive power. Lastly, analysis of the affective characteristics, visual learning preference and self-efficacy on ability exposed them to be significant predictors of student conceptual understanding.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.1
• /
• pp.9-21
• /
• 1998

This paper a new solution approach to moving obstacle avoidance problem of a mobile robot. A new concept avoidability measure (AVM) is defined to describe the state of a pair of a robot and an obstacle regarding the collision between them. As an AVM, virtual distance function (VDF), is derived as a function of the distance from the obstacle to the robot and outward speed of the obstacle relative to the robot. By keeping the virtual distance above some positive limit value, the robot avoids the obstacle. In terms of the VDF ,an artificial potential field is constructed to repel the robot away from the obstacle and to attract the robot toward a goal location. At every sampling time, the artificial potential field is updated and the force driving the robot is derived from the gradient of the artificial potential field. The suggested algorithm drives the robot to avoid moving obstacles in real time. Since the algorithm considers the mobility of the obstacle as well as the distance, it is effective for moving obstacle avoidance. Some simulation studies show the effectiveness of the proposed approach.

• Journal of Engineering Education Research
• /
• v.19 no.6
• /
• pp.32-37
• /
• 2016

The purpose of this study is to extract a skill level of human resource in the field of science and technology. To accomplish the goal of this study, precedent research was conducted and then, the draft of skill level for Human Resource in the field of Science and Technology (HRST) was created by wrap-up meeting. The skill level of the HRST was finalized after confirming verification of 20 SMEs (Subject Matter Experts) from January to February 2016 by two times. The conclusions are as follows; First, the skill level of the HRST consists five categories. Each of the level has educational background, work experience, certification, duty, major and so on. Second, the contents of the skill level were found to be mostly valid.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2001.02a
• /
• pp.57-60
• /
• 2001

In this paper, a design scheme of SMES coil with HTS wire(BSCCO 2223) for least stray field and conductor consumption is presented. Three types of coils (solenoid, multiple solenoid, and modular toroid) have been considered. Shape and size of the coil was decided by line element method with evolution strategy and confirmed with Finite Element Method. Modular toroid displayed least stray field with given conductor length. The goal of the study is to establish designing technology of a HTS coil for SMES which works in relatively high magnetic field.

• Proceedings of the IEEK Conference
• /
• 2002.07b
• /
• pp.790-793
• /
• 2002

In this paper, dynamic path planning of two mobile robots using a modified Hopfield neural network is studied. An area which excludes obstacles and allows gradually changing of activation level of neurons is derived in each step. Next moving step can be determined by searching the next highest activated neuron. By learning repeatedly, the steps will be generated from starting to goal points. A path will be constructed from these steps. Simulation showed the constructed paths of two mobile robots, which are moving across each other to their goals.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1998.03a
• /
• pp.88-93
• /
• 1998

This paper presents a new solution approach to moving obstacle avoidance problem for a mobile robot. A new concept avoidability measure(AVM) is defined to describe the state of a pair of a robot and an obstacle regarding the collision between them. As an AVM, virtual distance function(VDF) is derived as a function of the distance from the obstacle to the robot and outward speed of the obstacle relative to the robot. By keeping the virtual distance above some positive limit value, the robot avoids the obstacle. In terns of the VDF, an artificial potential field is constructed to repel the robot away from the obstacle and to attract the robot toward a goal location. At every sampling time, the artificial potential field is updated and the force driving the robot is derived form the gradient of the artificial potential field. The suggested algorithm drives the robot to avoid moving obstacles in real time. Since the algorithm considers the mobility of the obstacle as well as the distance, it is effective for moving obstacle avoidance. Some simulation studies show the effectiveness of the proposed approach.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.554-558
• /
• 2002

A magnetostrictive sensor is used to measure stress waves propagating in a ferromagnetic cylinder without physical contact. The performance of a magnetostrictive sensor is affected most significantly by the bias magnetic field applied around the measurement location. The goal of this paper is to carry out the topology optimization of the bias magnet and yoke assembly to maximize the sensor output for traveling bending waves. We will use the multi-resolution topology optimization strategy to find the assembly of the bias magnet and the yoke that is easy to realize. The effectiveness of the present design is confirmed by an actual measurement of the sensor signal with the proposed bias magnet and yoke configuration.