• Journal of KIISE:Databases
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• v.28 no.3
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• pp.384-394
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• 2001

In this paper, we propose AST-AET(Average valid Start Time-Average valid End Time) data migration strategy based on the storage structure where temporal data is divided into a past segment, a current segment, and a future segment. We define AST and AET which are used in AST-AET data migration strategy and also define entity versions to be stored in each segment. We describe methods to compute AST and AET, and processes to search entity versions for migration and move them. We compare average response times for user queries between AST-AET data migration strategy and the existing LST-GET(Least valid Start Time-Greatest valid End Time) data migration strategy. The experimental results show that, when there are no LLTs(Long Lived Tuples), there is little difference in performance between the two migration strategies because the size of a current segment is nearly equal. However, when there are LLTs, the average response time of AST-AET data migration strategy is smaller than that of LST-GET data migration strategy because the size of a current segment of LST-GET data migration strategy becomes larger. In addition, when we change average interarrival times of temporal queries, generally the average response time of AST-AET data migration strategy is smaller than that of LST-GET data migration strategy.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.6
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• pp.189-207
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• 2020

The government has achieved quantitative growth in university start-up education while supporting start-up education. However, it failed to systematize start-up education from an academic, policy, and practical perspective and to reveal the relationship between education and achievements in supporting start-ups. Therefore, there is a lack of interest and effort to promote effective education. In Europe, in-depth research has already been done over many years to establish an EntreComp system. Competences create values for others and attempt to apply them to education, viewing them as the people's lifelong competitiveness. On the other hand, it is urgent to improve the education system as domestic university start-up education is mainly focused on cultural level start-up skills and easy-to-access education from a business administration perspective. Based on this, the entrepreneurship competence-based start-up education system was designed. Next, eight EntreComp frames were drawn for university students through the Focus Group Interview (FGI) and Delphi survey methods, as well as domestic and international prior studies on EntreComp. In 2018, 919 start-up education programs of 42 start-up leading universities were conducted to derive the status of education by EntreComp. Prior studies of 25 entrepreneurship competences, including data from Bacigalupo et al.(2016), which studied EntreComp in the EU, were investigated and reflected the frequency of research and the importance of education and start-up perspectives. Based on the purpose of the university start-up education presented in this study, the entrepreneurship competence frame consisting of a total of eight, including spotting opportunities, value creation, self improvement, mobilising resources, technology application, strategic management, relationship, and learning through experience, was derived through expert verification. It also investigated the current status of education by competence, the degree of reflection of competence education, and the relationship with the results of support for start-ups that reflect the number of students enrolled in each university. Through this, it was suggested that future start-up education at universities could be improved from the EntreComp perspective. It has a differentiation in research in that it conducted a thorough survey using the data on start-up courses operated by leading startup universities for a certain period. However, it is difficult to generalize because the number of samples of leading startup universities is limited. Nevertheless, this study proposes the educational goal of advancing university start-up education from the perspective of entrepreneurial competence, cultivating future required competences, and fostering entrepreneurial talents that create value for others. In addition, it is meaningful in that it presents a clear direction for subsequent research by preparing a framework for research from a more essential perspective on the entrepreneurship competence frame.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.387-392
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• 2003

During a fault the remanent flux in a current transformer (CT) may cause severe saturation of its core. The resulting distortion in the secondary current could cause the mal-operation of a protection relay. This paper proposes an algorithm for compensating for the errors in the secondary current caused by CT saturation and the remanent flux. The algorithm compensates the distorted current irrespective of the level of the remanent flux. The second-difference function of the current is used to detect when the CT first starts to saturate. The negative value of the second-difference function at the start of saturation, which corresponds to the magnetizing current, is inserted into the magnetization curve to obtain the core flux at the instant. This value is then used as an initial flux to calculate the actual flux of the CT during the course of the fault with the secondary current. The magnetizing current is then estimated using the magnetization curve and the calculated flux value. The compensated secondary current can be estimated by adding the magnetizing current to the secondary current. Test results indicate that the algorithm can accurately compensate a severely distorted secondary current signal.

• Journal of Digital Convergence
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• v.16 no.9
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• pp.39-49
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• 2018

The research investigates the changes of current government policy for Micro-enterprises with respect to the government policy fund, start-up, management education and the relevant consulting services. The examination is used for providing the improving directions of Micro-enterprise government policy reflecting on the current Micro-enterprises. While Micro-enterprise belongs to the class of Small enterprise, the impact of the government policies in Micro-enterprise is much bigger than the other. For this reason, the fundamental investigation considering Micro-enterprise is crucial. In order to provide the improving directions, this research examines the incumbent government policies. Then, the analyses provides the changing agenda for Micro-enterprise. The suggestions contributes to the improving criteria for right paradigm of Micro-enterprise.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.700-706
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• 2012

The core technology of a starting device in the packaged power system is the pinion gear shifting device and to limit the initial starting voltage. Although the conventional products have been used the starting controller using mechanical contactor, these have a big problem such as the uncertainty for the start of starting motor after a pinion gear is completely shifted or the arc demage due to high current. In this study, in order to solve these problems, we designed and fabricated a new product to achieve the safety and reliability as follows: the pinion gear-shifting control circuits to eliminate the uncertainty of the start, the starting control system using semiconductor device to prevent the arc demage of contactor caused by high current, a start safety devices for soft starting of series motor. In addition, we obtained the electrical safety by separating the pinion gear control circuit and the source circuit of motor.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.397-400
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• 2002

The purpose of this study is to analyze current status and propose improvement scheme of safety management on the heavy construction equipment operation. The research method invloves interview and questionnaire survey for the analysis of practical use status of heavy construction equipment. The results of this study are as fallows: 1) The problem of safety management status on heavy construction equipment operation is surveyed not wearing safety helmet, not keeping work regulations, and not preparing the work before start. 2) Proposed improvement scheme of safety management on heavy construction equipment operation includes strengthening 5 minutes safety education before start, strengthening safety action against falling materials, and strengthening enough preparation before start.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.577-582
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• 2016

The synchronous TDC(Time-to-Digital Converter) of counter-type using current-conveyor is designed by $0.18{\mu}m$ CMOS process and the supply voltage is 3 volts. In order to compensate the disadvantage of a asynchronous TDC the clock is generated when the start signal is applied and the clock is synchronized with the start signal. In the asynchronous TDC the error range of digital output is from $-T_{CK}$ to $T_{CK}$. But the error range of digital output is from 0 to $T_{CK}$ in the synchronous TDC. The error range of output is reduced by the synchronization between the start signal and the clock when the timing-interval signal is converted to digital value. Also the structure of the synchronous TDC is simple because there is no the high frequency external clock. The operation of designed TDC is confirmed by the HSPICE simulation.

• Plant Journal
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• v.10 no.3
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• pp.34-38
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• 2014

Coal-fired power plants have used oil as fuel for start-up but plasma burner is recently introduced in order to reduce costs. It provides fuel oil-free start-up. But at initial operation of Plasma burner, an increase in unburned carbon remains as still pending issue. Also research and operational standards for this problem are insufficient. In this paper, operating procedure will be proposed through analyzing the impact of unburned carbon in accordance with the Plasma arc current. It is also possible to contribute to the national plant industry by demonstrating economics of Plasma burner in commissioning coal-fired power plants.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.9
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• pp.500-506
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• 2004

This paper proposes a modified current differential relay for transformer protection unaffected by the remanent flux. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. To cope with the remanent flux, before saturation, the relay calculates the core-loss current and uses it to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the actual core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. This paper concludes by implementing the relay on a hardware platform based on a digital signal processor. The relay discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.48-53
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• 2012

This paper is purposed to develop portable electric instrument to select NI-9223(National instrument comp.) and clamp meter(HIOKI comp.), which can be used in developing electric instrument, to detect leakage current(ZCT) and current(CT) signals. In this paper, The electric instrument that can interface with current and leakage current instrument(HIOKI 9283), is developed by NI-9223 of NI comp.. HIOKI clamp meter can measure current signals certainly by high-sensitivity of 10 ${\mu}A$ resolution(leakage current : at 10 mA range) and current 1~200A range. The NI-9223 use four 16-bit analog-to-digital converters(ADCs) for true simultaneous sampling at up to 1 MS/s per channel. NI-9223 can synchronize all analog input modules installed in the same chassis to share the same start clock and/or sample clocks. The monitoring program is developed by SignalExpress of LabVIEW. The monitoring program are developed to analyze at simultaneous sampling on electrical signals such as leakage current(ZCT) and current(CT). The developed system verification tests were conducted, and portable electric instrument can be used in place which requires analysis of the actual electrical signal.