• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.186-187
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• 2006

The development of SFCL (Superconducting Fault Current Limiter) is getting more important as the power demand is increased rapidly. Up to now, several kinds of SFCL have been proposed and it is expected that they will be applied to appropriate position considering their own properties. Amongst those proposed SFCL, flux-lock type SFCL using the magnetic cancelation for current limiting has the advantages of overcoming the technical difficulties that other types of SFCLs have. In this paper, the integrated three-phase flux-lock type SFCL was fabricated and its operational modes were investigated through the short circuit tests. The operational mode were to divided into four mode according to the variation of the currents flowing into the secondary winding connected the superconducting elements and the speed of the quench generation. It was expected that the improvement of current limiting characteristics of the SFCL could be possible through control of the operational mode.

• Journal of the Korean Institute of Telematics and Electronics
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• v.13 no.5
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• pp.24-29
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• 1976

In the phase locked AM signal detection, phase locked loop is used to extract a synchronous carrier from an input AM signal. Under the assumption that input noise is white Gaussian and free-running frequency of voltage controlled oscillator is the same that of an input carrier, operational behaviours of phase locked loop is analyzed and signal to noise ratio of the detection is derived quentitatively. The results show that the phase locked AM signal detection method offers a higher degree of noise mmunity than conventional AM signal detections.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.20-29
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• 2011

This paper presents an improved phase-shift pulse-width modulation (PWM) full-bridge converter using a blocking capacitor. As the proposed converter reduces the circulation energy by inserting only one series blocking capacitor at the primary side of the conventional phase-shift PWM full-bridge converter structure, it improves the operation characteristics of the conventional converter. In this paper, first, the operation of conventional phase-shift PWM full-bridge converter is roughly reviewed, and then the operational principle of the proposed converter is classified and explained by each mode. After that, a prototype design example based on the operational principle is shown. Then, the improved operation characteristics of the proposed converter are actually verified through the experimental results.

• Progress in Superconductivity and Cryogenics
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• v.8 no.2
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• pp.46-49
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• 2006

The 30m, 3phase, 22.9kV HTS (High Temperature Superconducting) power cable system was produced by LS Cable Ltd. The project aims for a commercial HTS cable. The designing, the manufacturing and the initial operating of HTS cable system were completed by 2004. Then, we have performed a long term operational test since February, 2005. This paper mainly reports the result of the HTS cable cooling operation.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1051_1052
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• 2009

This paper deals with operational characteristic analysis of a single-phase PCS (Power Conditioning System) for PV (Photovoltaic) power generation system with AF (Active Filter) function. The theory of dq transformation has been applied to the control strategy of a single-phase PV power generation system to implement the AF function. Application of the virtual two-phase using phase-shift makes it possible to use the dq theory for the single-phase PV power generation system. The authors are sure that the proposed system is a very useful to compensate harmonics caused by nonlinear loads in a single-phase utility system. In this paper, not only a theoretical aspect of the single-phase PV-AF system is discussed, but also the DSP (Digital Signal Processor) based experiment results are presented to demonstrate the effectiveness of the single-phase PV-AF system.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.624-635
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• 2015

Design space exploration has been much neglected in aircraft conceptual design phase, which often leads to a waste of time and cost in design, manufacture and operation process. It is necessary to explore design space based on operational system-of-systems (SoS) simulation during the early phase for a competitive design. This paper proposes a methodology to analyze aircraft performance parameters in four steps: combination of parameters, object analysis, operational simulation, and key-parameters analysis. Meanwhile, the design space of an unmanned aerial vehicle applied in earthquake search and rescue SoS is explored based on this methodology. The results show that applying SoS simulation into design phase has important reference value for designers on aircraft conceptual design.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.3 s.18
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• pp.47-58
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• 2004

This paper focuses on the technical information about the development of the submarine operational effectiveness simulation model for the feasibility study stage of the submarine design. The simulation model is classified into simulation control model and system model. Using user input and related performance parameters, it can simulate various scenarios by no change of the program because it includes tactic manager which makes decision about every situation. And the Monte-Carlo simulation mode which provides the stochastic results is available. Through the test simulation, the usefulness of the simulation model was verified. It should be helpful for the analysis of the submarine operational effectiveness by diversified scenarios in the concept design phase..

• Journal of Korea Multimedia Society
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• v.11 no.6
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• pp.891-902
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• 2008

The software once developed enters in to the $2^{nd}$ phase of its useful operational life, where it performs its functions for which it has been developed. This is an important phase of software life, wherein the developers and users have to assess the performance of the software to prolong its operational life with efficiency, effectiveness and economy. Performance of the software is based on the measurement of the quality characteristics to ascertain that it is meeting or exceeding the needs of customers in terms of its functionality, usability, efficiency, reliability, availability, maintainability, portability etc. These software quality attributes defined under ISO 9126 provide an overall good framework for assessing the performance of the software. This paper describes a Software Performance Assessment (SPA) model using the Goal-Question-Metric (GQM) paradigm which has been applied to the operational software in real context with successful results.

• Nuclear Engineering and Technology
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• v.31 no.1
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• pp.49-57
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• 1999

It has been a critical issue to predict the safety critical software reliability in nuclear engineering area. For many years, many researches have focused on the quantification of software reliability and there have been many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is however on the operational reliability rather than on the test reliability. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, from testing to operation, testing environment factors comprising the aging factor and the coverage factor are developed in this paper and used to predict the ultimate operational reliability with the failure data in testing phase. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results show that the proposed method can estimate the operational reliability accurately.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2325-2330
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• 2003

GPS based orbit determination system for the KOMPSAT-2 has been developed. Two types of orbit determination software such as operational orbit determination and precise orbit determination are designed and implemented. GPS navigation solutions from on-board the satellite are used for the operational orbit determination and raw measurements data such as C/A code pseudo-range and L1 carrier phase for the precise orbit determination. Operational concept, architectural design, software implementation, and performance test are described.