• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.300-305
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• 2013

The torque was calculated with inductance and iron loss. Because the linkage flux can change the inductance, and q-axis current can change the iron loss. Therefore, precise estimation of torque can achieve with the inductance and iron loss detail calculations. So, in this paper, the d, q-axis inductance was verified through CVCT(Current Vector Control Test) and DCT(Direct Current Test). Also in the iron loss calculation, the prediction of all areas of current magnitude, phase angle and speed was very difficult. And LUT(Look-Up Table) was spent time and resource largely. Therefore, iron loss mathematization was proposed according to current magnitude, phase angle and speed. Also, characteristics of IPMSM were comprised of analyzed and experimental values.

• Progress in Superconductivity
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• v.6 no.2
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• pp.113-117
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• 2005

In this study, electromagnetic analysis of current paths including meander pattern, spiral pattern, and bi-spiral pattern were performed and in order to verity the analysis results, experiments tests including quench test, and insulation tests were performed. In addition, bubble corner concepts were introduced to enhance insulation reliability. From our study, bi-spiral pattern of YBCO thin films were rather effective for quench and insulation than the other patterns. So this current path pattern was adopted for YBCO thin films in order to develop 6.6 kV resistive fault current limiters. Finally YBCO thin films were connected in series and parallel to enhance capacity, and the test results of current limiting characteristics of 6.6kV resistive SFCL were successful. The Progress in Superconductivity is published every six month and serves as a channel for publications on superconductivity and related topics. The author(s) are required to submit THREE copies of the manuscripts along with original figures directly to the Editor.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.1
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• pp.6-13
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• 2008

National standard system for calibrating current transformer(CT) up to primary current of 20,000A have been established. The system consists of 20,000 A AC high current source, CT comparator, standard CT, CT under test and CT burden. An AC high current is applied tn the primary windings of both the standard CT and the CT under test, and then the CT comparator measures the ratio error and the phase displacement by comparing the secondary currents of the two transformers. As a validity check for 20,000 A CT calibration system, the comparison with the two national standard institutes(NMIs) has been performed using same CTs. The comparison results of the CTs are consistent with those measured at two NMIs within 0.004 % for ratio error and 0.1 min for phase displacement in the primary current ranges of Ip = 10 - 20,000 A with a secondary current of Is = 5 A.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.2
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• pp.184-189
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• 2022

In this paper, the fault current limiting operations of three-phase transformer type superconducting fault current limiter (SFCL) using double quench, which consisted of E-I iron core with three legs wound by primary and secondary windings and two superconducting modules (SCMs), were analyzed according to three-phase ground fault types. To verify the effective operation of the three-phase transformer type SFCL using double quench, the test circuit for three-phase ground faults was constructed, and the fault current tests were carried out. Through analysis on the fault current test results, the different fault current limiting characteristics of three-phase transformer type SFCL using double quench from three-phase transformer type SFCL using three SCMs were discussed.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.57-63
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• 2013

PURPOSES: This study is to investigate the Hot In-Place recycling asphalt mixture in Korea using field produced materials. METHODS: Hot In-Place reclaimed asphalt mixture was investigated to evaluate the mixture properties based on various test results such as Marshall Test, Indirect Tensile Test, TSR, and Wheel Tracking Test. These test values were compared with domestic standard specification. RESULTS: The result of the laboratory experiment indicates that the Hot In-Place Reclaimed(HIR) asphalt mixture produced at the field constrution site was satisfied all of the test criteria such as Indirect tensile test, Marshall and TSR test, and wheel tracking test. During the test, the research team found that current HIR system is required an extention of mixing time to improve quality and to reduce variation of sample to sample. Although the current HIR mixture was passed the test criteria, there is a potential capability to enhance the mixture properties as extend mixting time. CONCLUSIONS: Based on these laboratory test results, It would be concluded that domestic HIR mixture's properties were satisfied all standard specification related with evaluation of recycling asphalt mixtures. Based on this case study result, there is a chance to save construction cost and increase the usage of reclaimed asphalt concrete in the future.

• Journal of the Korean institute of surface engineering
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• v.37 no.2
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• pp.110-118
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• 2004

The corrosion of pure titanium (CP- Ti Grade 2) and titanium alloy (Ti6Al4V ELI) were studied under various conditions of simulated body fluids. The static immersion test and the electrochemical test were performed in accordance with ISO 10271 : 2001. For the electrochemical test, the open circuit potential was monitored as a function of time, and the cyclic polarization curve was recorded. The corrosion resistance was evaluated from the values of corrosion potential, passivation current density, breakdown potential, and the shape of hysteresis etc. The effects of alloy type, surface condition, temperature, oxygen, and constituents in the fluids such as acid, chloride were estimated. Both specimens had extremely low dissolution rate in the static immersion test. They showed strong passivation characteristics in the electrochemical test. They maintained negligible current density throughout the wide anodic potential range. The passive layer was not broken up to 2.0 V (vs. SCE). The hysteresis and the shift of passivation potential toward the anodic direction was observed during the reversed scan. The passivation process appeared to be accelerated by oxygen in air or that dissolved in the fluids. The passivation also proceeded without oxygen by the reaction of constituents in the fluids. Acid or chloride in the fluids, specially later weakened the passive layer, and then induced higher passivation current density and less shift of passivation potential in the reversed scan. CP-Ti Grade 2 was more reactive than Ti6Al4V ELI in the fluids containing acid or chloride, but thicker layer produced on its surface provided higher corrosion resistance.

• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.29-33
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• 2003

The ferritic stainless steels are generally considered to have poor weldability compared with that of the austenitic stainless steels. However the primary advantages of ferritic stainless steels include lower material cost than the more commonly used austenitic stainless steels and a greater resistance to stress corrosion cracking. Thus, the weldability of ferritic stainless steels was investigated in this study. In concerning the weldability, Grain size measurement test, Erichsen test and Varestraint test were involved. full penetration welds were produced by autogeneous direct current straight polarity (DCSP) and pulsed currents gas tungsten arc welding (GIAW) and the effect of pulsed currents welding on the welds was compared to that of DCSP welding. The results showed that pulsed current was effective to refine grain size in the weld metal and the finest grain size was obtained at the frequency of 150Hz. In addition, the ductility of welds was lower than that of base metal. Finally, autogeneous type 444 welds were less susceptible to macro solidification cracks, but more sensitive to micro cracks; SEM/EDS analysis indicated that all the inclusions in the crack showed enrichment of Mn, Si, O and S.

• Journal of Power Electronics
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• v.18 no.2
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• pp.456-466
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• 2018

This paper introduces the development of a de-icer based on a full-bridge modular multilevel converter (FMMC). The FMMC can generate a wide range of DC voltages owing to its modularity, scalability, and redundancy, which makes it suitable for ice-melting applications. First, operating principles and voltage ranges are analyzed when FMMC is applied as a mobile de-icer. Second, two new startup strategies, constant modulation index and constant power startup strategies, are proposed. Third, the main control strategies of the de-icer are proposed. Fourth, a novel rated-current zero-power test scheme is proposed to simplify test conditions. Finally, a 10 kV 1.5 kA mobile MMC de-icer is designed and built, and experiments are carried out to validate the proposed startup, control strategies, and rated-current zero-power test scheme.

• East Asian Journal of Business Economics (EAJBE)
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• v.8 no.4
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• pp.1-18
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• 2020

Purpose - The current study attempts to reveal the causal relationship and identify the interrelationships among individual value, product selection attribute, and re-purchase intention of consumers when purchasing kimchi. Research design, data, and methodology - The surveys were distributed and retrieved to kimchi consumers in Seoul and Gyeonggi Province who were over 20 years old and who had purchased kimchi before. The current study utilized the self-reporting survey as the research method. Result - First, as a result of hypothesis 1 test, both internal value and external value had a significant effect. Second, as a result of hypothesis 2 test, while internal value had a significant effect, external value did not have a significant effect. Third, as a result of hypothesis 3 test, while internal value had a significant effect, external value did not have a significant effect. Fourth, as a result of hypothesis 4 test, all quality, brand, and price had a significant effect. Fifth, as a result of hypothesis 5 test, while internal value had a significant effect, external value did not have a significant effect. Conclusion - The current study aims to establish marketing and service strategies to maximize profits and secure competitive advantage in the kimchi industry through changes in the management strategy of the Korean kimchi industry.

• Proceedings of the Safety Management and Science Conference
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• 2010.04a
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• pp.231-237
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• 2010

The purpose of this study was to investigate the actual conditions of radiation safety supervision in animal clinics using quality assurance (QA) and quality control (QC) of diagnostic X-ray units. The surveys for QA/QC, equipment condition, and safety supervision were carried out in 18 animal clinics randomly. The QA/QC included reproducibility of dose exposure, kVp, mAs, collimator accuracy test, collimator luminance test, X-ray view box luminance test, grounding system equipment test and external leakage current test. As a result, 44.44% of reproducibility of dose exposure was proper, 81. 25% of kVp test was good, and 100% of mAs test was appropriate. Also, 66.66% of collimator accuracy test was proper, 61.11% of collimator luminance test was good, 53.13% of X-ray view box luminance test was suitable. In addition, only 5.55% of grounding system equipment and ground resistance was proper, 63.64% of external leakage current test was appropriate in grounding system equipment test.