• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.53-59
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• 2006

Need for agile satellite increases for performing various mission due to increase of satellite image applications and users. In high resolution satellite TDI (time delay and integration) method is adopted in order to improve SNR. But image quality can be degraded by satellite maneuver. In this paper requirements for remote sensing in high resolution satellite with agility are extracted and an approach to operate the agile satellite to perform the missions are proposed. The proposed approach in this paper will be applicable to system level design and analysis.

• Journal of Space Technology and Applications
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• v.3 no.4
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• pp.322-332
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• 2023

Satellite attitude-control actuators are equipped with a reaction wheel for three-axis attitude control. The reaction wheel rotates a motor inside the actuator to generate torque in the vector direction. When using the reaction wheel, there are restrictions on the torque values generated as the motor rotates. The torque value of the reaction wheels mounted on small satellites is approximately 10 mNm, and high values are not used. Therefore, three-axis attitude control of a small satellite is possible using a reaction wheel, but this method is not suitable for missions that require rapid attitude control at a specific time. As a technology to overcome the small torque value of the reaction wheel, the control moment gyro (CMG) is currently in wide use as a rapid attitude-control actuator in space satellites. The CMG has an internal gimbal mounted at a right angle to the rotation motor and generates a large torque value. In general, when the gimbal operates, a torque value approximately 100 times greater is generated, making it suitable for rapid posture maneuvering. Currently, we are developing a technology for mounting a controlled moment gyro on a small satellite, and here we share the development status of an 800 mNm CMG.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1299-1308
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• 2007

In this paper, we propose the calibration method of monopulse slope to minimize the variation of angle estimate in frequency agile noncoherent monopulse system. We analyze the monopulse slope characteristics of antenna and RF receiver including the phase and gain imbalances of each receiving channel and present the calibration method to minimize the phase and gain imbalances of RF receiver channels including antenna. In addition, we present the calibration method using channel switching to minimize the gain imbalance of IF receiver channels. The measured average monopulse slope within the frequency bandwidth is -0.96, the maximum variation of angle estimate is similar to theoretical value, $0.15^{\circ}$ at ${\pm}2^{\circ}$ azimuth and $0.03^{\circ}$ at $0^{\circ}$ azimuth.

• Journal of KIISE:Software and Applications
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• v.34 no.3
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• pp.179-195
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• 2007

Traditional software development method is not suitable for Web application development because of characteristics of Web application such as frequent requirements change, different architectures and models and quick-to-market delivery. In this paper we propose a Web application development method adaptable to requirements change while we systematically model Web application using extended UML model. The metamodel is independent to specific languages and technologies because we define the metamodel using extended UML model. Proposed process is described by SPEM(Software Process Engineering Metamodel) profile. A process supporting tool execute and customize process. To model Web applications systematically and effectively, a navigation modeling and a component communication modeling tools are provided. In a case study, we show the usefulness of our process and model.

• The Journal of Korean Association of Computer Education
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• v.23 no.3
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• pp.41-47
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• 2020

Computational Thinking(CT) is drawing attention as a core competency required for future talent in the 21st century. Software education for improving CT ability at home and abroad is in full swing. Among them, problem-solving programming education helps to improve CT ability. The CT-TDPS learning model follows the decomposition, abstraction thinking process, which modularizes complex problems, and the Agile development method, which is an iterative and incremental programming method to implement it. In this study, we tried to confirm the improvement of CT ability by applying CT-TDPS learning model to problem solving programming education using Scratch. As a result of the study, it was confirmed that in the problem solving programming education using the CT-TDPS learning model, it improved in all aspects of computing concept, computing performance, and computing perspective, which are sub-factors of CT ability. In addition, it was confirmed that there was a significant difference in the experimental group as a result of the t-test on the Dr.Scratch automatic evaluation result.

• Information Systems Review
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• v.13 no.1
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• pp.61-74
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• 2011

Software industry still has many deep-seated problems. As a natural consequence, it may have to learn from best practices in more mature industry like manufacturing. An example is 'lean' software development which is defined as translation of 'lean manufacturing' principles to the software development domain. The principles include 'eliminate waste' and 'amplify learning.' It was much asserted that these principles are worth applying. Not much study, however, was done on how to practically implement these principles into software development practice. In this study we attempt to present a method in which project lead time and software defects are regarded as major targets of management and are visualized using Cumulative Flow Diagram. We further applied this method on actual projects. The result confirms that agile is positively effective on reducing wastes.

• Journal of Information Processing Systems
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• v.8 no.4
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• pp.539-554
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• 2012

Model-driven and component-oriented development is increasingly being used in the development of embedded systems. When combined, both paradigms provide several advantages, such as higher reuse rates, and improved system quality. Performing model-driven and component-oriented development should be accompanied by a component model and a method that prescribes how the component model is used. This article provides an overview on the MARMOT method, which consists of an abstract component model and a methodology for the development of embedded systems. The paper describes a feasibility study that demonstrates MARMOT's capability to alleviate system design, verification, implementation, and reuse. Results indicate that model-driven and component-based development following the MARMOT method outperforms Agile development for embedded systems, leads to maintainable systems, and higher than normal reuse rates.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.83-92
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• 2001

In this paper, the monopulse channel receiver which can be matched between channels through a wide bandwidth has been proposed. The effects of the gain and phase imbalance between channels on the slope of monopulse error signal were analyzed. Also, the matching method between channels in a wide bandwidth was proposed, by which monopulse slope could be stabilized. Using the implemented monopulse radar system the monopulse slope was measured in the anechoic chamber which include the moving horn antenna and the target signal generator. The results show that the wide band matching method is useful and applicable to various channel receivers

• KIISE Transactions on Computing Practices
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• v.21 no.2
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• pp.115-120
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• 2015

The Testing Frontier Capability Assessment Model (TCAM) is based on ISO/IEC 9126, TMMi and TPI. Since ISO/IEC 9126, TMMi and TPI were made over 10 years ago, TCAM faces the problem that it can not assess and analyze the capability of small businesses that employ new software development methods or processes, for example Agile, TDD(Test Driven Development), App software, and Web Software. In this paper, a method to improve the problem is proposed. The paper is composed of the following sections: 1) ISO/IEC 9126, ISO/IEC 25010 and ISO/IEC/IEEE 29119 part 2 review 2) TCAM review 3) software product quality perspective comparison, and analysis between ISO/IEC 9126, ISO/IEC 25010 and TCAM 4) comparison, and analysis between ISO/IEC/IEEE 29119 part2 and TCAM and 5) proposal for the improvement of TCAM.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.1
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• pp.1-11
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• 2005

Several Solid Freeform Fabrication Systems(SFFS) are commercialized in a few companies for rapid prototyping. However, they have many technical problems including the limitation of applicable materials. A new method of agile prototyping is required for the recent manufacturing environments of multi-item and small quantity production. The objectives of this paper include the development of a novel method of SFFS, the CAFL/sup VM/(Computer Aided Fabrication of Lamination for Various Material), and the manufacture of the various material samples for the certification of the proposed system and the creation of new application areas. For these objectives, the technologies for a highly accurate robot path control, the optimization of support structure, CAD modeling, adaptive slicing was implemented. However, there is an important problem with the conventional 2D lamination method. That is the inaccuracy of 3D model surface, which is caused by the stair-type surface generated in virtue of vertical 2D cutting. In this paper, We design the new control algorithm that guarantees the constant speed, precise positioning and tangential cutting on the 5DOF SFFS. We develop the tangential cutting algorithm to be controlled with constant speed and successfully implemented in the 5DOF CAFL/sup VM/ system developed in this paper. Finally, this paper confirms its high-performance through the experimental results from the application into CAFL/sup VM/ system.