• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.251-254
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• 2004

Hybrid rockets have many advantages over solid and liquid rockets. Hybrid rockets put forth high $I_{sp}$ like liquid rockets in spite of simple structure and low cost. As oxidizer flow rate is increased, thrust of hybrid rocket is increased accordingly. In this study, lab-scale hybrid rocket is designed, fabricated and tested. This system consists of lab-scale hybrid rocket motor, ignition system, flow system and data aquisition system. In order to control oxidizer flow rate, we construct flow rate control system by using needle valve and stepping motor.

• Journal of the Korea Society for Simulation
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• 제19권4호
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• pp.301-308
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• 2010

As a new paradigm called modeling and simulation(M&S) or simulation based acquisition(SBA) has arisen, necessity of applying it to Korea has been increased. Not only rational construction of SBA but development of model which can evaluate driving results and improve relating processes to SBA is needed. Therefore we suggests the framework of capability maturity model for M&S development and SBA. The ultimate purpose of our model is improving processes relating to M&S development and SBA. The last section include detailed model which has practices for improving some SBA processes.

• Journal of the Korean School Mathematics Society
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• 제11권4호
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• pp.629-654
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• 2008

This study investigated school mathematics curriculum of the State of Georgia in the United States focused on the 'number and operation' and 'algebra' domain. On the basis of its understanding, this domain was compared and analyzed with school mathematics curriculum of Korea. In doing so, this study explored its plans and procedures and established a frame of comparison for the curriculums between the two countries. The most noticeable difference between the former and the new curriculum in mathematics for Georgia schools is the use of performance standards. A performance standard has four components: a content standard, illustrative tasks, examples of student work, and a commentary for teachers. This study focuses on the content standard and according to the results of the present study, Korea focuses on the formal and systematic mathematical knowledge on the basis of sound understanding of certain mathematical terms or concepts. On the other hand, the State of Georgia curriculum tends to deal with the content which can be understood more intuitively, flexibly, and naturally through the experience, aquisition, and furthermore interpretation based on the concrete manipulation and technological devices.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제29권8A호
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• pp.898-908
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• 2004

In this paper, we propose a high speed preamble searcher feasible for RACH(Random Access Channel) preamble structure in WCDMA reverse link receiver. Unlike IS-95, WCDMA system uses AISMA(Acquisition Indication Sense Multiple Access) process. Because of the time limit between RACH preamble transmission and AI(Acquisition Indicators), and the restriction on the number of RACH signatures assigned to RACH preamble, fast acquisition indication is required for efficient operation. The preamble searcher proposed in this paper is based on 2-antenna system and has adopted FHT algorithm that has the radix-2 16 point FFT structure. The acquisition speed using FHT is 64 times faster than the conventional method that correlates each signature. Based on their fast aquisition scheme, we improved the acquisition performance by calculating the correlation up to the 4096 chips of the total preamble length. The performance is analyzed by using Neyman-pearson method. The proposed algorithm has been applied for the implementation of WCDMA reverse link receiver modem successfully.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제10권1호
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• pp.127-135
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• 2006

The image-based 3D modeling is the technique of generating a 3D graphic model from images acquired using cameras. It is being researched as an alternative technique for the expensive 3D scanner. In this paper, I propose the image-based 3D modeling system using calibrated camera. The proposed algorithm for rendering 3D model is consisted of three steps, camera calibration, 3D shape reconstruction and 3D surface generation step. In the camera calibration step, I estimate the camera matrix for the image aquisition camera. In the 3D shape reconstruction step, I calculate 3D volume data from silhouette using pyramidal volume intersection. In the 3D surface generation step, the reconstructed volume data is converted to 3D mesh surface. As shown the result, I generated relatively accurate 3D model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제28권5호
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• pp.320-325
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• 2015

This paper dealt with a defect identification algorithm which is based on single partial discharge (PD) pulse analysis in gas insulated structure. Four types of electrode systems such as a needle-plane, a plane-needle, a free particle and a crack inside spacer were fabricated to simulate defects in gas insulated switchgear (GIS). We measured single PD pulse by an oscilloscope with a sampling rate of 5 GS/s and a frequency bandwidth of 1 GHz. Data aquisition and signal processing were controlled by a LabVIEW program. Physical shapes of PD pulses were compared with kurtosis, skewness and time-based parameters as rising time, falling time and pulse-width. These parameters were analysed by an algorithm with a back propagation algorithm (BPA). By applying the algorithm, the identification rate was 97% for the needle-plane electrode, 96% for the plane-needle electrode, 91% for the free particle and 93% for the crack inside spacer. The results verified that the algorithm could identify the type of defects in GIS.

• Archives of design research
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• 제13권3호
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• pp.169-180
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• 2000

With the change of design environment, the aquisition and application of appropriate information are regarded as greatly important, especially in the product development process for the next generation. It will be important that aquired information be transformed and applied to design information. With this framework, features of design information and its application were studied in this paper. First, the interrelationship of design and information was analyzed. Second, effective methods to collect various design information were classified and several guidelines with which to apply these methods were suggested. Third, the role of design information in the rapid development of computer, information and internet technology was analyzed and several recommendations were suggested. Finally, the information database for trend analysis, based on computer and internet technology was developed and its application was studied in order to show an example of the collection and application of design information.

• The Mathematical Education
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• 제45권4호
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• pp.407-438
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• 2006

This study investigated school mathematics curriculum of England, newly revised in 1998, focused on the 'shape, space, and measures' domain among three major domains of the English curriculum. On the basis of its understanding, this domain was compared and analyzed with school mathematics curriculum of Korea. In doing so, this study explored its plans and procedures and established a frame of comparison for the curriculums between the two countries. The structure of the National Curriculum in England is composed of programmes of study and attainment targets. The former sets out what should be taught in mathematics at key stages 1, 2, 3, and 4 and provides the basis for planning schemes of work, and the latter sets out the knowledge, skills, and understanding that pupils of different abilities and matures are expected to have by the end of each key stage. Attainment targets are composed of eight levels and an additional level of increasing difficulty. According to the results of the present study, Korea focuses on the formal and systematic mathematical knowledge on the basis of sound understanding of certain mathematical terms or concepts. On the other hand, England curriculum tends to deal with the content which can be understood more intuitively, flexibly, and naturally through the experience and aquisition based on the concrete manipulation. Particularly, it emphasizes that mathematics be realistic and useful in solving a diverse problems confronted in everyday life.

• The KIPS Transactions:PartD
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• 제8D권4호
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• pp.427-438
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• 2001

Recently, Environmental Control Devices of Green House for Protected Cultivation is composed of on/off-type Controller to control each device using timer in equipment of intensive Labor. In case of system, it is difficult to grasp condition of the greenhouse about errors when this system has defect of a hardware, and it operates in the remote place or at night. In this paper, we developed a system that capable of replacing the existing control method of on/off with display panel in the greenhouse, monitoring data aquisition and status in the greenhouse using client computer based on internet. Also this system can communicate with each local greenhouse, and send alarm message about error. And we constructed web server to manage efficient informations for environmental control and corps cultivation in the greenhouse.

• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.86-88
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• 1997

The detection of the normal zones in the coil winding and the initiation of the proper dump sequence have been one of the most important areas in the superconducting magnet technology. In this paper, the process to derive optimal dump sequence has been investigated through quench simulation and analysis of magnetically coupled superconducting magnet system. The magnet terminal voltage and maximum temperature rise in the quench initiated point are calculated with respect to various input variables such as operation current, dump resistance, etc. The experimental system is comprised of sc solenoidal coil, data aquisition device, external circuit breakers and dump resistor. The quench behavior of the magnet(e.g., temperature profile and the voltage signal) was measured. From this results, theoretical predictions were found to coincide with the experimental observations.