• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.9
• /
• pp.922-929
• /
• 2009

This paper deals with the State-Dependent Riccati Equation (SDRE) Technique for the design of helicopter nonlinear waypoint guidance controller. To generate the flight guidance through multiple waypoints, we use the trigonometric spline. The controller design and its validation is based upon a level 2 simulation helicopter model and the designed SDRE controller is applied to the trajectory tracking problems. To validate the designed SDRE controller, the simulation environment of high fidelity helicopter model is developed using three independent computers. This paper focuses on the validation the present SDRE controller through the helicopter waypoint guidance simulation.

• International Journal of Aeronautical and Space Sciences
• /
• v.12 no.1
• /
• pp.16-23
• /
• 2011

In this paper, nonlinear model predictive control (NMPC) is addressed to develop formation guidance for multiple unmanned aerial vehicles. An NMPC algorithm predicts the behavior of a system over a receding time horizon, and the NMPC generates the optimal control commands for the horizon. The first input command is, then, applied to the system and this procedure repeats at each time step. The input constraint and state constraint for formation flight and inter-collision avoidance are considered in the proposed NMPC framework. The performance of NMPC for formation guidance critically degrades when there exists a communication failure. In order to address this problem, the modified optimal guidance law using only line-of-sight, relative distance, and own motion information is presented. If this information can be measured or estimated, the proposed formation guidance is sustainable with the communication failure. The performance of this approach is validated by numerical simulations.

• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.4
• /
• pp.697-708
• /
• 2017

The complex battlefield environment makes it difficult to intercept maneuvering targets for guided missiles. In this paper, a finite-time convergent (FTC) guidance law based on the second-order sliding mode (SOSM) control theory is proposed to achieve the requirements of stability, accuracy and robustness. More specifically, a second-order sliding mode observer (SMOB) is used to estimate and compensate for the total disturbance of the controlled system, while the target acceleration is extracted from the line-of-sight (LOS) angle measurement. The proposed guidance law can drive the LOS angular rate converge to zero in a finite time, which means that the missile will accurately intercept the target. Numerical simulations with some comparisons are performed to demonstrate the superiority of the proposed guidance law.

• The Korean Journal of Pain
• /
• v.23 no.2
• /
• pp.137-141
• /
• 2010

Background: Facet joint have been implicated as a source of chronic low back pain. Radiofrequency denervation has demonstrated the most solid evidence. To increase safety and efficacy of treatment, computed tomography (CT) guidance injection has been used in several disease. The purpose of this study was to evaluate the efficacy of CT-guided radiofrequency rhizotomy in the treatment of facet joint pain. Methods: A total of 40 patients were randomized to undergo radiofrequency facet joint denervation under CT guidance or C-arm guidance. All patients were examined visual analogue scale (VAS) score before treatment, 1 month, and 3 months after treatment. Results: The VAS in both groups showed significant improvement over the 1-month interval. No significant difference in the VAS score among the group was observed. Conclusions: In this study there was no significant difference between CT guidance lumbar rhizotomy and C-arm guidance lumbar rhizotomy. Therefore CT-guided radiofrequency denervation of the lumbar facet joint was a minimally invasive technique that appears effective.

• Water Engineering Research
• /
• v.4 no.4
• /
• pp.203-214
• /
• 2003

The severe flood disaster by a typoon Rusa was occurred in the last year in Korea. The Rusa brought the rainfall of 870.5mm per a day in the city of Kangnung, Kangwon-do, Korea and this rainfall amount is 62% of the annual mean rainfall in this area. Our focus is to investigate the flash flood guidance and the sediment yield for the basins of small streams of Yangyang town in Kangnung area. Say, the flash flood guidance and the sediment yield by the Rusa are estimated and compared with the given informations obtained from the past flood events. As the results, the flash flood guidance and sediment yield in the study area showed much bigger values than the given informations and so we could know that the Rusa influenced the severe flood of the study area.

• Research in Mathematical Education
• /
• v.27 no.2
• /
• pp.195-210
• /
• 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 Korean Society for Agricultural Machinery Conference
• /
• 2000.11b
• /
• pp.333-343
• /
• 2000

An automatic guidance system for combine was designed to harvest paddy rice by following a predetermined path. The automatic guidance system consisted of DGPS to locate position of combine, a gyro sensor system to measure heading angle, ultrasonic sensors to detect obstacles, a hydraulic system, microcomputer as a controller, and I/O interface system. Hydraulic cylinders and valves were installed to control movement of the combine. The heading angle and the position of the combine, and ultrasonic measurements from edge were used as the inputs of the controller. The operating position of hydraulic cylinder was determined as output of the controller. The automatic guidance system was evaluated at the 45-m straight path by changing the posture of the combine. The average RMS errors were 14.0 cm without offset and 15.0 cm with 1-m offset. The DGPS provided accurate position information within the limited error to guide the combine in the field. The results showed that the automatic guidance system could guide the combine autonomously in the paddy field when the posture of the combine was changed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.11
• /
• pp.1417-1423
• /
• 2020

This paper proposes a waypoint guidance algorithm for the Autonomous Underwater Vehicle(AUV). The proposed simplified guidance algorithm is presented, which is combined LOS guidance and cross-track guidance for path following. Cross-track error is calculated using the position of the AUV and reference path. LOS guidance and cross-track guidance are appropriately changed according to cross-track error. And the stability of the system has been improved using variable cross-track control gain by cross-track error. Also, in this paper, navigation hardware in-the loop simulation(HILS) is implemented to verify navigation algorithm of AUV that performs combined navigation using inertial navigation device and doppler velocity log(DVL). Finally, we design integrated system HILS (including navigation HILS) for performance verification of guidance algorithm of the autonomous underwater vehicle. By comparing the sea test result with HILS result, the proposed guidance algorithm and HILS configuration were confirmed be correct.

• Journal of Korean Library and Information Science Society
• /
• v.45 no.4
• /
• pp.21-44
• /
• 2014

The purpose of this study is to research and determine a systematic operating method for analyzing vacation reading guidance programs in school library systems and, thereby, suggesting ways of operating a reading guidance program both effectively and efficiently. Analyses of questionnaires going out to hundred of school libraries in Gyeonggi Province will be performed for this purpose. Specifically, the study will analyze the following 1) the current operation status of each program, 2) their initial purposes and focus, 3) targeted children groups, 4) program instructors, and 5) the actual content design of the programs. As a result, the vast majority of the school libraries operation of vacation reading guidance program and purpose of inspire of reading interest. Finally this study suggests the 5 directions to support operation of vacation reading guidance program in School Libraries. The results of this study will likely suggest the need to re-align or shift current vacation reading guidance programs to be more inclusive for all participants.

• Journal of Korean society of Dental Hygiene
• /
• v.17 no.6
• /
• pp.1225-1235
• /
• 2017

Objectives: The purpose of this study is to examine the effects of parents' oral health management behavior towards children on children's oral health. Methods: Dental examination were done to 82 children, and a survey was conducted to 82 parents of them. This researcher conducted multiple regression analysis to figure out how parents' oral health management behavior towards their children influences their oral health condition. Results: Among the kinds of parents' oral health management behavior towards their children, when they received a lower score in guidance for dietary control, children tended to have more dt index. Among the kinds of parents' oral health management behavior towards their children, guidance for tooth brushing and guidance for oral care influenced their children's O'leary index. When they received a higher score in guidance for tooth brushing and guidance for oral care, their children's O'leary index became lower. Conclusions: This study has found that parents' dietary guidance provided to children influences their dt index, and O'leary index, one of the major causes of dental caries, is influenced by parents' guidance for tooth-brushing and guidance for oral care. Therefore, we should realize that according to the degree of parents' interest in children's oral care, children's state of oral health can be changed, and parents should acquire proper knowledge about oral health and instruct and train their children desirably.