• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.6
• /
• pp.1428-1442
• /
• 2007

Nowadays, as IT environment is changing rapidly, traditional infra system such as hardware, software, and development methodology are changing as well. Legacy system has been filled with Intellectual property such as invested budget and development period for the time of IT is developing. Many countries around the world are having troubles with how to manage the legacy system. It is time to study on a development method and the implementation of supporting tool to reuse or process the legacy system. In this paper, it proves the definition, concept and also background of legacy system by showing real market and technology trend. Developed to handle the concrete development methodology, procedure and reference. We can get more profitability and productivity advance by reuse of legacy system and maintenance cost-saving through legacy migration.

• The KIPS Transactions:PartD
• /
• v.14D no.7
• /
• pp.763-772
• /
• 2007

Due to increased software development cost, interest about the method and automated tool for reusing legacy system have been running high. Therefore, In this study, it proves the definition, concept and also background of legacy system by showing real market and technology trend. Automation tool is designed and developed to handle the concrete development methodology, procedure and reference. Also, we implemented the process that analyze the legacy system and extract, refine, store and reuse the candidate components by using LM(Legacy to Modern System) supporting tool presented in this paper. If LM supporting tool is applied to legacy system migration, we can expect cutting costs, shortening the developing period and succeeding the intellectual property by software re-engineering.

• Journal of Power Electronics
• /
• v.11 no.5
• /
• pp.759-766
• /
• 2011

This paper focuses on monitoring and predicting the short circuit faults of the rotor windings of large turbo-generator systems. For the purpose of increasing efficiency and decreasing maintenance cost, a method that combines the HHT (Hilbert Huang Transform) with a wavelet has been studied. This method is based on analyzing a classical Albright detecting coil. Due to the Empirical Mode Decomposition (EMD) and the Intrinsic Mode Functions (IMF) of the HHT the exact location of a short circuit of rotor windings may be given. However, a part of the useful information is eliminated by the unreasonable decomposing scale of the wavelet. Based on the thermodynamics modeling method, this study was illustrated with a 50MW turbo-generator system that is installed in Northern China. The analysis results, which have very good agreement with those of a previous study, show that the method of combining the HHT with a wavelet is an effective way to analyze and predict the short circuit faults of the rotor windings of large generators, such as supercritical turbo-generator systems and wind turbo-generator systems. This work can offer a useful reference for analyzing smart grids by improving the power quality of a distribution network that is supplied by a turbo-generator system.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.7
• /
• pp.1865-1872
• /
• 1997

This paper proposes not only the thresholding problem which has been one of the major problems in the pre-existing edge detection method but also the removal of blurring effect occurred at the edge regions due to the smoothing process. The structure of a given image is assigned as one of the three predefined image structure classes by evaluating its toll membership value to each reference structure class:The structure of an image belongs to the structure class which has the least cost value with the image. Upon the structure class assigned, noise removal and edge extraction precesses are performed, e.g., the smoothing algorithm is applied to the image if its structure belongs to the pure noise region class; edge extraction while removing the noise is performed simultaneously if the edge structure class. The proposed method shows that preventing the blurring effect can be usually seen in the edge images and extracting the edges with no using thresholding value by the experiments.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.2
• /
• pp.328-338
• /
• 2017

In this paper, a zero torque control scheme adopting current sharing function (CSF) used in integrated Switched Reluctance Motor (SRM) drive with DC battery charger is proposed. The proposed control scheme is able to achieve the keeping position (KP), zero torque (ZT) and power factor correction (PFC) at the same time with a simple novel current sharing function algorithm. The proposed CSF makes the proper reference for each phase windings of SRM to satisfy the total charging current of the battery with zero torque output to hold still position with power factor correction, and the copper loss minimization during of battery charging is also achieved during this process. Based on these, CSFs can be used without any recalculation of the optimal current at every sampling time. In this proposed integrated battery charger system, the cost effective, volume and weight reduction and power enlargement is realized by function multiplexing of the motor winding and asymmetric SR converter. By using the phase winding as large inductors for charging process, and taking the asymmetric SR converter as an interleaved converter with boost mode operation, the EV can be charged effectively and successfully with minimum integral system. In this integral system, there is a position sliding mode controller used to overcome any uncertainty such as mutual inductance or DC offset current sensor. Power factor correction and voltage adaption are obtained with three-phase buck type converter (or current source rectifier) that is cascaded with conventional SRM, one for wide input and output voltage range. The practicability is validated by the simulation and experimental results by using a laboratory 3-hp SRM setup based on TI TMS320F28335 platform.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2004.05b
• /
• pp.804-806
• /
• 2004

As a noninvasive imaging meathod, optical coherence tomography system has been extensively studied because it has some advantage such as imaging of high resolution, low cost, and compace size configuration. The optical power of the sample signal reflected from an object is usually very small in optical coherence tomography(OCT) due to absorption and scattering in a sample material. Furthermore, there happens a serious loss of sample signal power in a fiber coupler because it does not transfer to a photodetector but return to the optical source. In order to improve the SNR of OCT system, basic Michelson and Mach-Zehnder interferometer types were configured then, we compared simulation with measurement of reference sample Therefore, an On in configuration of Math-Zehnder interferometer was demonstrated in order to improve the signal to noise ratio

• Journal of the Korean Institute of Gas
• /
• v.12 no.2
• /
• pp.85-91
• /
• 2008

The deviation of measured pressures in pipeline networks from normal or reference pressures is useful information for judging the operation of the pipeline networks. A cost-effective monitoring of pipeline networks including a leak detection capability can be realized when transient pressure variation is accurately predicted using measured conditions at supply- and demand-sides of the networks. In this study, a pipeline network analysis program was developed based on one-dimensional flow equations for compressible fluids. The validity of the present analysis was demonstrated by simulating the flow in a straight pipeline and comparing the results with the previously reported ones. Pressure and flow rate transients in several simple city-gas pipeline networks were also analyzed to show the usefulness of the developed program.

• Journal of Korean Society of Transportation
• /
• v.24 no.5 s.91
• /
• pp.67-74
• /
• 2006

This paper proposes a way to a risk quantification of public sector comparator in the value-for-money test of the BTL (Build-Transfer-Lease) scheme in rail investment projects. Two principal risks that are project delay and budget increasing costs are identified and are empirically quantified with a case study of the Haman-Jinju link. The methodology suggested is expected to be a good reference for the similar research afterwards and also to help in settling down the scheme that is only an early stage.

• The Journal of the Korea Contents Association
• /
• v.9 no.6
• /
• pp.196-206
• /
• 2009

The profitability of a hospital refers to business administration results achieved through its medical care and other management activities during applicable fiscal year. This study focused on operating margin as a measurement index of hospital profitability, which is a genuine medical return obtained by subtracting medical expenses from medical profits achieved during business administration of hospital. Based on the index, this study could deduce certain factors on hospital profitability in terms of various indices affecting profitability. And based on those factors, this study sought to provide more useful reference materials which allow us to devise possible ways to improve hospital profitability. As a result, it was found that public hospitals attained lower profitability than private ones. To analyze profitability depending on each index, this study divided hospitals broadly into deficit group and surplus group. As a result, it was found that there were significant differences in hospital profitability between two groups depending upon relevant indices such as labor cost ratio, maintenance expense ratio, number of operations per medical specialist and medical instrument turnover. According to analysis on potential effects of relevant indices upon profitability, it was found that each index had its explanatory power ranging from 25% to 74.5% depending on given model.

• Journal of Power Electronics
• /
• v.18 no.6
• /
• pp.1729-1750
• /
• 2018

Voltage source inverters (VSIs) are widely used to drive induction motors in industry applications. The quality of output waveforms depends on the switching sequences used in pulse width modulation (PWM). In this work, all existing optimal space vector pulse width modulation (SVPWM) switching strategies are studied. The performance of existing SVPWM switching strategies is optimized to realize a tradeoff between quality of output waveforms and switching losses. This study generalizes the existing optimal switching sequences for total harmonic distortions (THDs) and switching losses for different modulation indexes and reference angles with a parameter called quality factor. This factor provides a common platform in which the THDs and switching losses of different SVPWM techniques can be compared. The optimal spatial distribution of each sequence is derived on the basis of the quality factor to minimize harmonic current distortions and switching losses in a sector; the result is the minimum ripple loss SVPWM (MRSLPWM). By employing the sequences from optimized switching maps, the proposed method can simultaneously reduce THDs and switching losses. Two hybrid SVPWM techniques are proposed to reduce line current distortions and switching losses in motor drives. The proposed hybrid SVPWM strategies are MRSLPWM 30 and MRSLPWM 90. With a low-cost PIC microcontroller (PIC18F452), the proposed hybrid SVPWM techniques and the quality of output waveforms are experimentally validated on a 2 kVA VSI based on a three-phase two-level insulated gate bipolar transistor.