• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.142-145
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• 2002

This paper describes an influence of system voltage harmonics on arrester deterioration diagnostic techniques based on leakage current measurement because the resistive current is composed of two components caused by nonlinear characteristics of arrester and by system voltage harmonics. Resistive leakage currents of arresters, which can be evaluated by the third harmonic component of total leakage currents, increase with its deterioration progress. In this paper, we developed a PSpice model for ZnO arrester to simulate the harmonics' effect described above. In simulation, pure sinusoidal voltage and the $3^{rd}$ harmonic voltage are applied to the model, and the leakage current changes are compared. The simulation results showed that the magnitudes of resistive leakage current depend not only on the phase of system voltage harmonics but also on the magnitude of it.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.91-102
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• 2005

In the past it was generally felt that software quality was the same as product quality. But as the software industry is getting bigger and more complex, it has become hard to develop quality software that meets customers' needs just depending on product quality. Therefore, lately many domestic and foreign companies are making efforts to upgrade product quality by implementing Process Improvement. Measurement in Process Improvement activities enhances the effect of Process Improvement, and also identifies and helps the activities. In support of this paper, research on the measurement program was conducted based on the CMMI adopted by many domestic and foreign companies for their process improvement model. MA process area that deals with measurement process setup is one of the CMMI process areas and was the basis of the structure of the measurement program. This study presents differences of the measurement program for each level of CMMI and how to apply it. The results of this study can help a business to apply CMMI-based Process Improvement by backing up the structure of the measurement program. Furthermore, it can offer a roadmap for progress of the measurement program for each level.

• Wind and Structures
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• v.18 no.5
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• pp.549-566
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• 2014

In spite of progress in the numerical simulation of typhoon wind field in atmospheric boundary layer (ABL), using typhoon wind field model in conjunction with Monte Carlo simulation method can only accurately evaluate typhoon wind field over a general terrain. This method is not enough for a reliable evaluation of typhoon wind field over the actual complex terrain with surface roughness and topography variations. To predict typhoon wind field over the actual complex terrain in ABL, a hybrid numerical simulation method combined typhoon simulation used the typhoon wind field model proposed by Meng et al. (1995) and CFD simulation in which the Reynolds averaged Navier-Stokes (RANS) equations and k-${\varepsilon}$ turbulence model are used. Typhoon wind filed during typhoon Dujuan and Imbudo are simulated using the hybrid numerical simulation method, and compared with the results predicted by the typhoon wind field model and the wind field measurement data collected by Fugro Geotechnical Services (FGS) in Hong Kong at the bridge site from the field monitoring system of wind turbulence parameters (FMS-WTP) to validate the feasibility and accuracy of the hybrid numerical simulation method. The comparison demonstrates that the hybrid numerical simulation method gives more accurate prediction to typhoon wind speed and direction, because the effect of topography is taken into account in the hybrid numerical simulation method.

• International Journal of Quality Innovation
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• v.10 no.2
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• pp.77-96
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• 2009

Industry competition environment is not being meaning of internal and external distinction. This may be phenomenon of globalization progress. In this time, we wish to examine present level in our enterprise and also analyze cause relation between 7 category of China Excellence Performance model which is modified Malcolm Baldridge Model and compare with China enterprise by using the same questionnaire with China. It is right opportunity to obtain information by comparing China enterprise with the Korea. This questionnaire composition and contents used as it is questionnaire contents that enforce in 2007 in China CAQ. The survey on Korea enterprises' is 509 by KSA in 2008, China is surveyed 1679 by CAQ in 2007. In Korea 'leadership', 'strategy planning', 'customer and market', 'measurement, analysis and improvement' 'resources management' and 'process management' stronger than China, but in China 'performance results' is stronger than Korea.

• Progress in Superconductivity and Cryogenics
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• v.25 no.1
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• pp.16-20
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• 2023

The International Electrotechnical Commission (IEC) 61788-26:2020 provides guidelines for measuring the critical current of Rare-earth barium copper oxide (REBCO) tapes using two methods: linear ramp and step-hold methods. The critical current measurement criterion, 1 or 0.1 μV/cm of electric field from IEC 61788-26 has been normally applied to REBCO coils or magnets. No-insulation (NI) winding technique has many advantages in aspects of electrical and thermal stability and mechanical integrity. However, the leak current from the NI REBCO coil can cause distortion in critical current measurement due to the characteristic resistance which causes the radial current flow paths. In this paper, we simulated the NI REBCO coil by applying both linear ramp and step-hold methods based on a simplified equivalent circuit model. Using the circuit analysis, we analyzed and evaluated both methods. By using the equivalent circuit model, we can evaluate the critical current of the NI REBCO coil, resulting in an estimation error within 0.1%. We also evaluate the accuracy of critical current measurement using both the linear ramp and step-hold methods. The accuracy of the linear ramp method is influenced by the inductive voltage, whereas the accuracy of the step-hold method depends on the duration of the hold-time. An adequate hold time, typically 5 to 10 times the time constant (τ), makes the step-hold method more accurate than the linear ramp method.

• Progress in Superconductivity and Cryogenics
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• v.19 no.2
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• pp.48-52
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• 2017

Discrepancy between a power supply current and an actual "spiral" coil current makes the conventional 4-probe measurement of a critical current ($I_c$) of a no-insulation (NI) high temperature superconductor (HTS) coil inaccurate and time-consuming. This paper presents a fast and accurate approach for $I_c$ measurement of NI HTS coils. With an NI HTS coil energized at a constant ramping rate, a complete analytic expression for the spiral coil current was obtained from a first-order partial differential equation that derived from an equivalent circuit model of the NI coil. From the analytic solution, both spiral coil current and radial leak current can be obtained simultaneously, which enables fast and accurate measurement of the NI coil $I_c$. To verify the proposed approach, an NI double-pancake (DP) coil, wound with GdBCO tapes of $6mm{\times}0.1mm$, was constructed and its $I_c$ was repeatedly measured with various ramping rates in a bath of liquid nitrogen at 77 K. The measured results agreed well with the calculated ones, which validates the proposed approach to measure $I_c$ of an NI HTS coil.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.4
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• pp.59-69
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• 2016

We proposed a specialized model of performance measurement to measure the training performance of the trainees in cyber practical training. Cyber security professionals are cultivating their expertise, skills, and competencies through cyber practical training in specialized education and training institutions. The our proposed process of trainee evaluation is consisted of an evaluation component discovery, evaluation item selection, evaluation index catalog, ratings and criteria decision, and calculation formula. The trainee evaluation is consisted of a formative evaluation during the training and an overall evaluation after finished training. Formative evaluation includes progress evaluation and participation evaluation, and overall evaluation includes practice evaluation and learning evaluation. The evaluation is weighted according to the importance of evaluation type. Because it is evaluated actual skills and abilities, competencies are assigned a high weight, while knowledge and attitudes are assigned a low weight. If cyber security trainees are evaluated by the proposed evaluation model, cyber security professionals can be cultivated by each skill and knowledge level and can be deployed by importance of security task.

• Korean Journal of Construction Engineering and Management
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• v.12 no.1
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• pp.73-84
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• 2011

This study represents construction progress management model based on quality inspection process in addition to cost-schedule integration. Quality inspection process cycle, resource estimate as progress measurement parameter, hierarchical structure of schedule, and inspection lots linking quality inspection to resource estimate are addressed as four main information areas. The authors established several process models to give a structure and correlations among information elements on each of these areas. Applying the process models proposed, an information system was implemented and utilized for nuclear power plant construction. It reveals that the system achieves accurate and objective progress information in near real time with significantly reduced time and effort as well as administrative efficiencies from making quality inspection process online.

• Progress in Superconductivity and Cryogenics
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• v.1 no.1
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• pp.33-37
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• 1999

The fast current and field ramp-up experiment was done with the superconducting magnet that is made of three non-insulated strand CICC (Cable-In- Conduit Conductor). The shunt the unbalanced current magnet enabled the unbalanced current measurement which is believed to be associated with the loop current. To explain the generation of the loop current during the current ramp up. the steady-state three strand loop current model was proposed. This model gives an explanation for the relation between the loop current and the twist geometry of the strands. According to this model. The twisr geometry and the surface contact resistance of the strand has significant influence on the generation of the loop current especially in the large superconducting magnet.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.6
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• pp.532-540
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• 2019

This study describes a test method for evaluating the ice friction and abrasion performance of polar coatings. The evaluation methods of physical properties of general coatings for ocean-going vessels and polar coatings for ice-going vessels were investigated and their limitations were analyzed. We have also reviewed previous researches related to the development of polar paints and confirmed the necessity of developing test techniques. A flat steel plate was coated with several types of commercial coating, and cold model ice was used to cause ice friction and abrasion events between coated surface and ice. For evaluation of ice friction and abrasion performances, test procedures such as measurement of coating surface roughness, measurement of frictional force using model ice, implementation of ice abrasion and drying of coating surface were developed. The friction and abrasion characteristics of each coating are analyzed and summarized through the change of friction force and roughness data according to the progress of ice abrasion.