• Research in Mathematical Education
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• v.27 no.2
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• pp.195-210
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• 2024

Researchers and curricula continue to call for proof to serve a central role in learning of mathematics throughout kindergarten to grade 12 and beyond. Despite its prominence and recognition gained during past decades, proof is still a stumbling block for both teachers and students. Research efforts have been made to address issues related to teaching and learning of proof. An area in which such research efforts have been made is analysis of curriculum material (i.e. textbook analysis) with a focus on proof. This study is another research effort in this area of research through investigating the guidance offered in curriculum materials with the following research question: What is the nature (e.g., kinds of content knowledge, pedagogical content knowledge) of guidance is offered for teachers to implement proof tasks in grade 8 geometry textbooks? Results indicate that the guidance offered for proof tasks are concerned more with content knowledge about the content-specific instructional goals than with pedagogical content knowledge which supports teachers in preparing in-class interactions with students to teach proof.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3079-3085
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• 2011

Through Korean Urban Maglev Program started in 2006, an urban maglev train was developed and the demonstration line is under construction as of now in 2011. The target speed of the developed maglev train is 110km/h, and the core technologies for super speed maglev trains over 500km/h are being studied. The propulsion and levitation systems of the super speed maglev train under consideration consist of linear synchronous motors (LSM) and levitation electromagnets which also act as a mover of LSM. In addition, guidance electromagnets are used to ensure stable running on curved tracks during super speed operation. The levitation and guidance control is focused on in this paper. For experimental purpose, a small maglev train is being manufactured, and its levitation and guidance controller is studied. The main task of the controller is to maintain the gap between the corresponding electromagnet and the guideway constantly. In general, measurements of the gap, acceleration and current and so on are utilized, and the gap control is implemented independently for each electromagnet. In this paper, the levitation and guidance system is modelled considering mechanical interactions, and the levitation and guidance controller is proposed based on this model. The developed controller is verified by various simulations using MATLAB/Simulink.

• Journal of the Korean Society for Library and Information Science
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• v.46 no.1
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• pp.77-97
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• 2012

The purpose of this study was to investigate the difference of the reading guidance for the youth among personality types. This presented the desirable way of the reading guidance through the differences. For this study, the data was collected through observation and focus group interview while reading guidance was implemented among senior year elementary school students and middle school students. This study revealed the possibility of the reading guidance based on personality type. As a result of the reading guidance, this showed the differences between personality type and reading attitude; and between reading tendency and product writing of the youth.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.117-125
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• 2017

Research on Maglev (Magnetic Levitation) train is currently being conducted in Korea, concerning Urban Transit (110 km/h of maximum speed), semi-high-speed (200 km/h of maximum speed), and high-speed (550 km/h of maximum speed) trains. This paper presents a research study on the levitation and guidance systems for the Korean semi-high-speed maglev train. A levitation electromagnet was designed, and the need for a separate guidance system was analyzed. A guidance electromagnet to control the lateral displacement of the train and ensure its stable operation was then also designed, and its characteristics were analyzed. The dynamic performance of the designed levitation and guidance electromagnets was modeled and analyzed, using a linearized modeling of the system equations of motion. Lastly, a test setup was prepared, including manufactured prototypes of the designed system, and the validity of the design was verified and examined with performance evaluation tests.

• The Journal of Korea Robotics Society
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• v.11 no.1
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• pp.1-8
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• 2016

In this paper, we propose a new algorithm of the guidance line extraction for autonomous agricultural robot based on vision camera in paddy field. It is the important process for guidance line extraction which finds the central point or area of rice row. We are trying to use the central region data of crop that the direction of rice leaves have convergence to central area of rice row in order to improve accuracy of the guidance line. The guidance line is extracted from the intersection points of extended virtual lines using the modified robust regression. The extended virtual lines are represented as the extended line from each segmented straight line created on the edges of the rice plants in the image using the Hough transform. We also have verified an accuracy of the proposed algorithm by experiments in the real wet paddy.

• Journal of Oral Medicine and Pain
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• v.13 no.1
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• pp.85-93
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• 1988

The author studied maximum clenching EMG activities of temporalis anterior and masseter muscle during canine guidance and centric occlusion. It was performed before and after anesthesia of maxillary and mandibular canines. The 22 normal subjects (15 males and 7 females) who had healthy maxillary and mandibular canines were selected. Their occlusal contact scheme was canine guidance during movement and they did not have temporomandibular disorder. The results were as follows : 1. The maximum clenching EMG activities of temporalis anterior and masseter muscle during guidance were less than those during centric occlusion. 2. After left maxillary and mandibular canines were anesthetized with 2% lidocanine with 1:100,000 epinephrine, the maximum clenching EMG acivities of temporalis anterior and masseter muscle during left canine guidance were greater than those before anesthesia of left maxillary and mandibular canines(p<0.01) 3. The maximum clenching EMG activities of temporalis anterior and masseter muscle during right guidance were not significantly different between before and after anesthesia of left maxillary and mandibular canines(p>0.05).

• International Journal of Aeronautical and Space Sciences
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• v.10 no.1
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• pp.30-36
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• 2009

Many formation guidance laws have been proposed for VAV formation flight. Since most autonomous formation flight methods require various active communication links between the vehicles to know motion information of other vehicles, damage to the receiver or the transmitter and communication delay are critical problem to achieve a given formation flight mission. Therefore, in this point of view, the method that does not need an inter-vehicle communication is preferred in the autonomous formation flight. In this paper, we first summarize the formation guidance law without an inter-vehicle communication using feedback linearization and sliding mode control proposed in previous study. We also propose the modified formation guidance law with robust disturbance observer, which can provide significantly better performance than previously mentioned guidance law in case that other vehicles maneuver with large accelerations. The robust disturbance observer can estimate uncertainties generated by acceleration of leader vehicle. By eliminating the uncertainties using the estimated uncertainties, VAVs are able to achieve the tight formation flight. The performance of the proposed approach is validated by numerical simulations.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.308-309
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• 2016

This paper deals with ship's track keeping methods which is crucial part of automatic navigation control systems. In this paper, we mainly discuss the performance of different guidance methods including way point guidance, enclosure-based steering guidance and lookahead-based steering guidance system. As a controller, a PID control system is employed to control ship's rudder angle during track-keeping. Finally, the performance of three methods are discussed through some simulation results.

• Journal of Korean Society of Transportation
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• v.27 no.2
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• pp.207-214
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• 2009

This study proposed an advanced warning information system based on real-time traffic conflict analysis. An algorithm to detect and analyze unsafe traffic events associated with car-following and lane-changes using individual vehicle trajectories was developed. A positive guidance procedure was adopted to provide warning information to alert drivers to hazardous traffic conditions derived from the outcomes of the algorithm. In addition, autoregressive integrated moving average (ARIMA) analyses were conducted to investigate the predictability of warning information for the enhancement of information reliability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.8
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• pp.662-670
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• 2017

This paper proposes an optimization-based procedure to determine the parameters of the Apollo guidance law for Korean lunar lander mission. A lunar landing mission is formulated as a trajectory optimization problem to minimize the fuel consumption and the reference trajectory for the lander is obtained by solving the problem in the pre-flight phase. Some parameters of the Apollo guidance, which are coefficients of the polynomial used to define the guidance command, are selected based on the reference trajectory obtained in the pre-flight phase. A case study for the landing guidance of Korean lunar lander mission using the proposed procedure is conducted to demonstrate its effectiveness.