• International conference on construction engineering and project management
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• 2011.02a
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• pp.99-106
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• 2011

Recent demands from construction industry have emphasized the capability for graduates to have improved skills both technical and non-technical such as problem solving, interpersonal communication. To satisfy these demands, problem-based learning that is an instructional method characterized by the use of real world problem has been adopted and has proven its effectiveness various disciplines. However, in spite of the importance of field senses and dealing with real problem, construction engineering education has generally focused on traditional lecture-oriented course. In order to improve limitations of current construction education and to satisfy recent demands from construction industry, this paper proposes a new educational approach that is Failure-Based Learning for using combination of the procedural characteristics of the problem-based learning theory in construction technology education utilizing failure information that has the educational value in the construction area by reinterpreting characteristics of construction industry and construction failure information. The major results of this study are summarized as follows. 1) Educational effect of problem-based learning methodology and limitation of application in construction area 2) The educational value of the information on construction failure and limitation in application of the information in construction sector 3) Anticipated effect from application of the failure-based learning 4) Development and application of the failure-based learning model

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1752-1758
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• 2018

In a low-voltage distribution system, the molded case circuit breaker (MCCB) is a widely used device to protect loads by interrupting over-current; however the hot gas generated from the arc discharge in the interrupting process depletes the dielectric recovery strength between electrodes and leads to re-ignition after current-zero. Even though the circuit breaker is ordinarily tripped and successfully interrupts the over-current, the re-ignition causes the over-current to flow to the load again, which carries over the failure interruption. Therefore, it is necessary to understand the dielectric recovery process and the dielectric recovery voltage of the MCCB. To determine these characteristics, a measuring system comprised of the experimental circuit and source is implemented to apply controllable recovery voltage and over-current. By changing the controllable recovery voltage, in this work, re-ignition is driven repeatedly to obtain the dielectric recovery voltage V-t curve, which is used to analyze the dielectric recovery strength of the MCCB. A measuring system and an evaluation technique for the dielectric recovery strength of the MCCB are described. By using this system and method, the measurement to find out the dielectric recovery characteristics after current-zero for ready-made products is done and it is confirmed that which internal structure of the MCCB affects the dielectric recovery characteristics.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.28.2-28.2
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• 2017

Using numerical hydrodynamics code RAMSES, we perform idealized galaxy merger simulations and study the star formation of merging disk galaxies. In our simulations, we consider the active galactic nucleus (AGN) feedback effect. In order to investigate the star formation influenced by AGN, we run ~60 simulations with various initial conditions. We confirm that star formation is more efficiently suppressed in merging galaxies than in isolated galaxies. In the mergers, AGN effect is more significant when the masses of two galaxies are similar. Furthermore, we find that bulge fraction does not affect the star formation when the AGN effect is considered. We discuss the implications on semi-analytic galaxy formation models and the limitation of the current AGN prescriptions.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.359-363
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• 1989

Recently, it is reported that the behavior of thermal $SiO_2$ under high electric field and current condition has a major effect on MOS device degration. Furthermore, when thin oxide films are applied in practical device, the presence of oxide defects will be a serious problem. In this paper, because TDDB is the useful method to measure the effective density of defects, we stressed MOS structure that is 150 A of thermally grown $SiO_2$as a function of electric field (9-19 MV/cm), temperature ($22^{\circ}C$ - $150^{\circ}C$) and current. By examing TDDB under positive voltage, long-term oxide breakdown reliabiliy is described. From these data, breakdown wearout limitation for the oxide films can be characterized.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.230-236
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• 2014

Superconducting fault current limiter (SFCL) has been expected as one of more effective solutions for decreasing fault current instantaneously and various types of SFCLs have been developed to apply into real power system. Recently, the application of the SFCL in a power distribution system has been reported to be contributed to the suppression of the voltage sag as well as the limitation of the fault current. However, the suppressing effect of voltage sag by the SFCL depends on component of its impedance and its application location in a power distribution system considering the recloser-recloser coordination. This paper analyzed the voltage sag caused by recloser-recloser coordination in a power distribution system and the suppression of the voltage sag due to the application location of the SFCL in a power distribution system was discussed through the PSCAD/EMTDC simulation.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.203-210
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• 2002

The past bridge design specifications of Korea didn't include 1imitation on the amount of lap splices in the plastic hinge zone of piers, and so do current specifications. But these specifications include just limitation on the minimal length of lap splices. Thus, a large majority of non-seismically designed bridge piers may have lap splices in plastic hinge zone. In this study, model pier was selected among existent bridge piers whose failure mode is complex shear-flexure mode. Full scaled RC pier models whose aspect ratio is about 2.67 were constructed and quasi static test according to the drift level history was implemented. From the test results, effect of the lap splices on the seismic performance of bridges piers was analyzed, and the seismic capacity of the model bridges was evaluated by capacity spectrum method.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.114-118
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• 1989

Due to the increased integration density of VLSI circuits a highly reliable thin oxide film is required to fabricate a small geometry MOS device. The behavior of thermal $SiO_2$ under high electric field and current condition has a major effect on MOS device degration and also the practical use of MOS device under irradiation has cause the degration of thin oxide films. In this paper, in order to evaluate the reliability of thin oxides with no stress applied and stressed by the irradiation under low electric field, the tests of TDDB (Time-dependent-dielectric breakdown) are used. Failure times against electric field are examined and acceleration factor is obtained for each case. Based on the experimental data, breakdown wear out limitation for thin oxide films is characterised.

• Journal of Society of Preventive Korean Medicine
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• v.3 no.1
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• pp.35-54
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• 1999

This thesis shows about the meaning of treatment rate increasing, the current treated level and the reason of low treatment rate and increasing methods. 1. Treatment rate incresing means high treat level within short time, keeping treatment effect for a long time as well as raising treatment rate. 2. The current by diseases each others completed treatment rate of oriental medicine is 14.0% to 89.7%$(mean:\;{\pm}40.0%)$. Therefore the rate is show too low. 3. The reasons of low treatment rate; low academic level of oriental, academic limitation, clinic and prevention problem of oriental medicine, lack of medical approch suitable for current diseases and symptoms, mostly incurrable diseases using oriental medicine, lack of preventive education, disappropriate medical service and nonspecialty of the treatment, etc. 4. The next methods for incresing the treatment rate must be improved; such as accurate establishment of process that diagnosis symptoms and treats them, system research of microdiagnosis, positive treatment with medicine and nonmedicine method at the same time, appropriate subdivision and actualization of clinical basic research, research of dose and response, diversity of treatment methods and forms, development of treatment service and prevention based on health level, enormous change as cure medicine and opening-up of new disease field, specialization of medical examination, reinforcement of public medical part and herbal drugs use with same origin, mental and pysical stability of patients, accurate extract and oral drinking ways, etc.

• Journal of Information Technology Services
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• v.12 no.3
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• pp.151-163
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• 2013

It is no doubt that information technology is the key factor of national safety. Information technology is positively useful for national security such as crime prevention and detection, criminal investigation, disaster management, and national defense. However, it might be a threat to the security as we saw in the examples such as '3.4 DDoS attacks' and 'Nong-hyup Computer Network Failure.' Although the effect that information technology makes upon the national security is immense, the current legal system does not reflect these changes well. National security should be kept during 'prevention-response-recovery' process regardless it is in the online on offline. In addition, public administration for national security should be based on laws. However, the current legal system is lack of legislative basis on cyber and physical disaster, and the laws on the response to disaster might cause confusing. Therefore, this study examines the limitation of the current legal system on national security, and suggests directions for the development of the system based on the new establishment of the legal concept for 'national security'.

• Journal of the Korean Society for Railway
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• v.10 no.4
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• pp.414-419
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• 2007

The contact characteristics of the current collection system are investigated by analyzing data collected during a test run of the Korean high speed rail vehicle. For the analysis, the signals from accelerometers and load cells attached to the various parts of the pantograph are analyzed in both the time and frequency domains. In the frequency domain, the pantograph response consists of low frequency components related to the rigid-body motion of the panhead assembly and high frequency components due to the structural vibration modes of the pantograph. The analysis shows that the inclusion of the high frequency structural vibration modes of the pantograph in the contact force calculation has a negligible effect on the predicted mean value of the contact force but significantly affects the magnitude of its fluctuations. This finding implies that numerical simulations using lumped element models of the pantograph may accurately predict the mean contact force but is limited in its capacity for predicting the fluctuation about the mean. Since the ratio of the fluctuation to the mean in the contact force increases with increased train speed, the limitation of the predictions based on numerical simulation results becomes more pronounced at higher train speed.