• Journal of the Korean Solar Energy Society
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• v.38 no.2
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• pp.1-13
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• 2018

This paper deals with the NREL (National Renewable Energy Laboratory) 5-MW reference wind turbine. The controller which include MPPT (Maximum power point tracking) control algorithm and tower load reduction control algorithm was designed by MATLAB Simulink. This paper propose a tower damper algorithm to improve the existing tower damper algorithm. To improve the existing tower damper algorithm, proposed tower damper algorithm were applied the thrust sensitivity scheduling and PI control method. The thrust sensitivity scheduling was calculated by thrust force formula which include thrust coefficient table. Power and Tower root moment DEL (Damage Equivalent Load) was set as a performance index to verify the load reduction algorithm. The simulation were performed 600 seconds under the wind conditions of the NTM (Normal Turbulence Model), TI (Turbulence Intensity)16% and 12~25m/s average wind speed. The effect of the proposed tower damper algorithm is confirmed through PSD (Power Spectral Density). The proposed tower damper algorithm reduces the fore-aft moment DEL of the tower up to 6% than the existing tower damper algorithm.

• Journal of Drive and Control
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• v.18 no.2
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• pp.20-31
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• 2021

An excavator is a construction machine that can perform various tasks such as trenching, piping, excavating, slope cutting, grading, and rock demolishing. In the 2010s, unmanned construction equipment using ICT technology was continuously developed. In this paper, the path design process was studied to implement the output data of the decision stage, and the path design algorithm was developed. For example, the output data of the decision stage were terrain data around the excavator, excavator mechanism information, excavator hydraulic information, the position and posture of the bucket at key points, the speed of the desired bucket path, and the required excavation volume. The result of the path design was the movement of the hydraulic cylinder, boom arm, bucket, and bucket edge. The core functions of the path design algorithm are the function of avoiding impact during the excavation process, the function to calculate the excavation depth that satisfies the required excavation volume, and the function that allows the bucket to pass through the main points of the excavation process while maintaining the speed of the desired path. In particular, in the process of developing the last function, the node tracking method expressed in the path design table was newly developed. The path design algorithm was verified as this path design satisfied the JCMAS H02 requirement.

• Journal of Korea Entertainment Industry Association
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• v.5 no.2
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• pp.87-95
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• 2011

Recently, the issue has been tangible game environment due to the various interactive interface developments. In this paper, we propose the multi card touch based interactive arcade system by using marker recognition interface and multi-touch interaction interface. For our system, the card's location and orientation information is recognized through DI-based recognition algorithm. In addition, the user's hand gesture tracking informations are provided by the various interaction metaphors. The system provides the user with a higher engagement offers a new experience. Therefore, our system will be used in the tangible arcade game machine.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.391-394
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• 2022

최근 한국을 포함한 여러 국가들에서 프로그래밍 교육이 중요시 되고 있다. 그러나 이런 상황으로 인해 더 많아진 학생들은 미숙함으로 인해 숙련자에 비해 더 많은 오류를 만나지만 이를 해결하기 위한 디버깅 실력은 아직 미숙하다. 따라서 본 논문에서는 프로그래밍 교육 지원을 위한 초보자용 GUI 디버깅 도우미 UDB (Unity-DeBugger)를 제안한다. UDB는 제출한 학생 코드를 분석하여 반응형 추적표와 오류 로그를 생성하고 이를 기반으로 GUI 및 애니메이션으로 만들어 학생과 상호작용한다. 특히 UDB는 반응형 추적표를 통해 프로그램 안에 있는 변수들의 현재 상태를 보여주고 순방향 추적뿐만 아니라 기존 IDE의 디버깅 도구들과는 다르게 역방향 추적이 가능하다는 큰 특징이 있다. 이런 UDB를 예시 코드에 실제로 적용한 결과를 통해 미숙한 학생도 역방향 추적 기능을 사용하여 오류 원인을 쉽게 찾을 수 있음을 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12B
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• pp.1022-1036
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• 2004

In mobile cellular network the ever-changing location of a mobile host necessitates the continuous tracking of its current position and efficient management of location information. A database called Home Location Register(HLR) plays a major role in location management in this distributed environment, providing table management, index management, and backup management facilities. The objectives of this paper are to identify the p개blems of the current HLR system through rigorous analysis, to suggest solutions to them, and to propose a new architecture for the HLR system. In the HLR system, a main memory database system is used to provide real-time accesses and updates of subscriber's information. Thus it is suggested that the improvement bemade to support better real-time facilities, to manage subscriber's information more reliably, and to accommodate more subscribers. In this paper, I propose an efficient backup method that takes into account the characteristics of HLR database transactions. The retrieval speed and the memory usage of the two-level index method are better than those of the T-tree index method. Insertion md deletion overhead of the chained bucket hashing method is less than that of modified linear hashing method. In the proposed backup method, I use two kinds of dirty flags in order to solve the performance degradation problem caused by frequent registration-location operations. Performance analysis has been performed to evaluate the proposed techniques based on a system with subscribers. The results show that, in comparison with the current techniques, the memory requirement is reduced by more than 62%,directory operations, and backup operation by more than 80%.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.1-12
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• 2011

Large-sized multi-touch screen is usually made using infrared rays. That is because it has technical constraints or cost problems to make the screen with the other ways using such as existing resistive overlays, capacitive overlay, or acoustic wave. Using infrared rays to make multi-touch screen is easy, but is likely to have technical limits to be implemented. To make up for these technical problems, two other methods were suggested through Surface project, which is a next generation user-interface concept of Microsoft. One is Frustrated Total Internal Reflection (FTIR) which uses infrared cameras, the other is Diffuse Illumination (DI). FTIR and DI are easy to be implemented in large screens and are not influenced by the number of touch points. Although FTIR method has an advantage in detecting touch-points, it also has lots of disadvantages such as screen size limit, quality of the materials, the module for infrared LED arrays, and high consuming power. On the other hand, DI method has difficulty in detecting touch-points because of it's structural problems but makes it possible to solve the problem of FTIR. In this thesis, we study the algorithms for effectively correcting the distort phenomenon of optical lens, and image processing algorithms in order to solve the touch detecting problem of the original DI method. Moreover, we suggest calibration algorithms for improving the accuracy of multi-touch, and a new tracking technique for accurate movement and gesture of the touch device. To verify our approaches, we implemented a table-based multi touch screen.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.45-50
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• 2009

The educational exchange through e-learning is working very well in such case as develop e-learning, development of various learning tools, cooperative practical use of e-learning contents, etc. However because there were no considerations of LMS(Learning Management System) interconnection when each systems were developed, the exchange through e-learning is starting to raise a problem. Especially the exchange through e-learning between university produced problem for a variety of reasons by absence of direct exchange in every case such as communication of students information, communication of lecture information, etc. Hence in this thesis, I will present designed model about efficient LMS interconnection through analysis case of exchange through e-learning and deduce problem. In the first place I define essential part for study such as lecture establishment data, lecture data, user data, class data, student learning tracking to interconnection data, then constituted data interconnection table used view by data interconnection prcess. By experiment result, the accessibility between students and professors was more convenience, and decreased work process by less data exchange. Henceforth there are researches in development of various essential parts for study, considered security of LMS interconnection.

• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.640-645
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• 2011

The educational exchange through e-learning is working very well in such case as develop e-learning, development of various learning tools, cooperative practical use of e-learning contents, etc. However because there were no considerations of LMS(Learning Management System) interconnection when each systems were developed, the exchange through e-learning is starting to raise a problem. Hence in this thesis, this paper presents designed model about efficient LMS interconnection through analysis case of exchange through e-learning and deduce problem. In the first place essential part for is defied study such as lecture establishment data, lecture data, user data, class data, student learning tracking to interconnection data, then constituted data interconnection table used view by data interconnection process. By experiment result, the accessibility between students and professors was more convenience, and decreased work process by less data exchange. Henceforth there are researches in development of various essential parts for study, considered security of LMS interconnection.

• Computers and Concrete
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• v.31 no.5
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• pp.457-468
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• 2023

Buildings, bridges, and dams are examples of civil infrastructure that play an important role in public life. These structures are prone to structural variations over time as a result of external forces that might disrupt the operation of the structures, cause structural integrity issues, and raise safety concerns for the occupants. Therefore, monitoring the state of a structure, also known as structural health monitoring (SHM), is essential. Owing to the emergence of the fourth industrial revolution, next-generation sensors, such as wireless sensors, UAVs, and video cameras, have recently been utilized to improve the quality and efficiency of building forensics. This study presents a method that uses a target-based system to estimate the dynamic displacement and its corresponding dynamic properties of structures using UAV-based video. A laboratory experiment was performed to verify the tracking technique using a shaking table to excite an SDOF specimen and comparing the results between a laser distance sensor, accelerometer, and fixed camera. Then a field test was conducted to validate the proposed framework. One target marker is placed on the specimen, and another marker is attached to the ground, which serves as a stationary reference to account for the undesired UAV movement. The results from the UAV and stationary camera displayed a root mean square (RMS) error of 2.02% for the displacement, and after post-processing the displacement data using an OMA method, the identified natural frequency and damping ratio showed significant accuracy and similarities. The findings illustrate the capabilities and reliabilities of the methodology using UAV to evaluate the dynamic properties of structures.

• Journal of the Korean Society of Earth Science Education
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• v.10 no.1
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• pp.50-61
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• 2017

The purpose of this study is to analysis eye tracking for high school students' learning styles in the process of solving in the behavioral domains of the College Scholastic Ability Test on Earth Science I. The subjects of this study were 50 students from two classes out of 4 classes in E high school in Chungcheong province. Among them, we conducted experiments by randomly sampling 2 students of each type of learning based on the criteria that they had not encountered the problem of Earth Science I from the past two years. The findings indicate that the item correctness rate of divergers, assimilators, convergers, and accommodators were higher in the knowledge domain, application domain, knowledge-understanding domain, and understanding domain. This confirms that there is a difference among the four learning styles in the level of achievement according to the behavioral areas of the assessment questions. The latter finding was that the high eye-share of AOI 2 appeared higher than AOI 1, 3, 4 in the course of solving the problems. This is because the four types of learners pay more careful attention to the AOI 2 area, which is the cue-or-information area of problem solving, that is, the Table, Figure, and Graph area. Therefore, in order to secure the fairness and objectivity of the selection, it is necessary that an equal number of questions of each behavioral domain be selected on the Earth Science I Test of the College Scholastic Ability Test in general. Besides, it seems to be necessary that the knowledge, understanding, application, and the behavior area of the inquiry be highly correlated with the AOI 2 area in development of test questions.