• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.108-114
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• 2008

The aim of this analysis is to verify the electrical compatibility of the interfaces which exist between TWTA(Travelling Wave Tube Amplifier) which is equipment of the Ka-band payload in COMS (Communication, Ocean and Meteorological Satellite) and external equipments. For each interface, this study checked the compatibility between equipments for the power links, commands, digital telemetry, analog telemetry, and failure condition or AIT(Assembly, Integration and Test) errors. In addition with this interface compatibility verification, this study outputs electrical and manufacturing recommendations to be applied at harness level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.329-335
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• 2019

Reliability growth analysis was conducted for a guided weapons system. In the development phase, reliability management activities were continuously carried out by identifying failure modes and causes and analyzing faults found during the testing. The missile system consists of an all-up-round missile and a launcher, and the analysis was carried out according to the test results of each system. The test results for the all-up-round missile were obtained with discrete data, which were success and failure as a one-shot-device. The test results for the launcher were obtained with continuous data by operating the equipment continuously in the test. For each test result, the reliability growth model was applied to the Standard Gompertz model and the Crow-Extended model. The models were used to identify the growth analysis results of the test so far. It was also possible to predict the reliability growth results by assuming the future test results. The study results could be useful in achieving the desired reliability goal and in determining the number of tests. Then, the planned test will be confirmed and the growth analysis of the missile system will continuously be conducted.

• Journal of the Korean Institute of Gas
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• v.23 no.4
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• pp.1-9
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• 2019

Large-scale industrial boilers operating at high temperature and high pressure, have a large amount of water, and a large amount of energy is released at the time of explosion. Currently, most industrial boilers use gas fuel such as LNG and LPG, etc. and fuel exists in the same space as equipment, so there is a high possibility of secondary damage such as fire or explosion in the event of a boiler accident. Both special care and management are required to operate the very dangerous equipment that causes casualty 2.51 per accident. For boilers of a certain size or more, the Korea Energy Agency conducts inspections in accordance with the Energy Usage Rationalization Act, KS, and public notice of the Ministry of Industry, Trade and Resources. In this research, based on the results of the inspection, the hazard factorss are configured, and a questionnaire is conducted to the inspector, the equipment manager, the maintenance person, and the person in charge of the manufacturer. We analyzed the results by using AHP (Analytic Hierarchy Process). As a result of analysis, generally recognized hazard factorss are not good management, measurement failure, specification failure, water leak, leak analysis, but connection, welding, scale, and corrosion, etc. are relatively less important. It is judged that the adverse factors that are recognized to be highly important among all groups and careers are already well managed, but less important and adverse factors should be well managed to ensure that the safe usage of the boiler.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.198-201
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• 2009

As a way to improve the safety of automotives and to reduce the weight of vehicles, new forming technologies and advanced materials are in high demand in the automotive industry. However, the advanced strength steel has inferior formability and large springback. In order to overcome such drawbacks, the hot press forming process (HPF) has been being applied for forming of automotive sheet parts. In this work, new equipment was suggested to measure unlimited displacement range compared to previous one which was able to measure only up to 10mm displacement range. The external extensometer connected with grips by wire was applied to equipment so that total strain range was measured up to failure also in high temperature. And the finite element analysis was conducted to characterize the mechanical properties of the HPF steel. Finally, the flow curves were represented by utilizing the Johnson-Cook type equation both in uniform and post-uniform deformation regions.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.428-433
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• 2010

According as economy grows, demand for power increases and satisfaction of customer about electricity quality is rising. There is in trend that investment expense by continuously increased supply of electric power equipment is on the increase continuously, but management efficiency improvement through curtailment of supply of electric power equipment investment expense through efficient operation is required rather than to increase investment. In this study, reconsidered about 6 divisions 3 ties that is distribution line basis configuration of Daejeon Geumsan area and analyzed division and tie present condition of truthful distribution System. Examined problem analyzing average division number, tie number and tie switch number, searched about most suitable division that consider load. Hereafter, I wish to take advantage of analysis result in most suitable division and tie of truthful distribution system for power failure section reduction and investment expense curtailment.

• Journal of the Korean Institute of Gas
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• v.6 no.1 s.17
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• pp.86-91
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• 2002

This study introduces a method that selects equipments, so as to reach the reliability level, carrying out an optimization analysis which considers the reliability data and cost of the equipments. A more practical optimization problem has been formed using the object function based on the discrete function and the constraints. The jacked reactor being the subject, an optimization analysis was performed on equipments that have different failure rates depending on costs in order to reach the target reliability level required by the system. The mixed-integer programming (MIP) was used for this optimization analysis. When the jacked reactors target level of reliability was $1.65{\times}10^{-4}$, the result of the analysis showed the equipments with high cost and low failure rate were selected. However when the target level of reliability was low, the result showed that by choosing the equipments with lower cost and reliability over the more expensive one, the desired target level could be reached.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.22-33
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• 2008

The plane strain test has been used widely in order to examine the stress-strain relation and failure behavior. Its advantages are more realistic simulation of deformation and failure behaviors of soils. Most plane strain tests have been carried out with restrained end plates due to difficulties in manufacturing the equipment with free end condition and also performing it. In this study, plane strain tests with/without bottom plate restraint were performed on Jumunjin-sand. The measurement of overall and local deformation was accomplished by digital image correlation technique as well as external LVDT. By applying digital image correlation method using two consecutive images captured through the transparent wall, local deformation behavior of various parts inside the specimen was estimated. From digital image analysis result, the restrained effect of end plate was examined about formation and development of shear band, and deformation mechanism of sand under plane strain condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1315-1323
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• 2010

This paper deals with a case study on a unique slope failure in a liner system of a municipal solid waste containment facility during construction because the sliding interface is not the geomembrane/compacted low permeability soil liner (LPSL) but a soil/soil interface within the LPSL. From the case study, it is concluded that compaction of the LPSL should ensure that each lift is kneaded into the lower lift so a weak interface is not created in the LPSL, and the LPSL moisture content should be controlled so it does not exceed the specified value, .e.g., 3% - 4% wet of optimum, because it can lead to a weak interface in the LPSL. In addition, drainage materials should be placed over the geomembrane from the slope toe to the top to reduce the shear stresses applied to the weakest interface, and equipment should not move laterally across the slope if it is unsupported but along the slope while placing the cover soil from bottom to top.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.887-895
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• 2017

This paper presents a study on the accelerated life tests of parts that operate during the opening and closing of door frames, particularly door hinges. Hinge theoretical verification and validation of the test equipment in the present study and the different structures and fault mode, depending on the purpose of usage analysis, failure mode for one of the hinges of the switchgear components used for electromagnetic shielding facilities and on-site operating conditions. The accelerated life test was designed for the characteristic lifetime prediction of the components, by estimating the shape parameter and the acceleration factor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1669-1674
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• 2017

In this study, We have discussed the development of a diagnostic device to detect and prevent electrical fire due to the arc caused by contact failure and partial disconnection at the connection part of the three-phase electric heater wiring used in the industrial field. The arc caused by contact failure and partial disconnection at the connection part of the electric heater shows a change in the current effective value. Therefore, it is possible to determine whether there exists a defect by analyzing the current unbalance factor and the number of current fluctuations with the diagnostic apparatus. The three-phase unbalanced heater is considered to be capable of determining defects through periodic measurement and trend analysis of the current unbalance factor. It is also expected that this device can be used not only for electric heaters but also for detection of defects in wiring and connections of electrical equipment having a characteristic of constant load current.