• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.765-771
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• 2012

$SF_6$ gas has been used as arc quenching and insulating medium for high and extra high voltage switching devices due to its high dielectric strength, its excellent arc-quenching capabilities, its high chemical stability and non toxicity. Despite of its significant contributions, the gas was classified as one of the greenhouse gas in the Kyoto Protocol. Thus, many researches are conducted to find out the replacement materials and to develop the $SF_6$ gas useless electrical equipment. This paper describes experiments on the temperature change-related breakdown characteristics of $SF_6$ gas ($SF_6$) and $SF_6$ liquid ($LSF_6$) in a model GIS(Gas-Insulated Switchgear) chamber in order to show the possibility of more stable and safe usages of $SF_6$ gas. The breakdown characteristics are classified into three stages, namely the gas stage of $SF_6$ according to Paschen's law, the coexisting stage of $SF_6$ gas with liquid in considerable deviation at lower temperature, and the stage of $LSF_6$ and remaining air. The result shows that the ability of the $LSF_6$ insulation is higher than the high-pressurized $SF_6$. Moreover, it reveals that the breakdown characteristics of $LSF_6$ are produced by bubble-formed $LSF_6$ evaporation and bubbles caused by high electric emission and the corona. In addition, the property of dielectric breakdown of $LSF_6$ is determined by electrode form, electrode arrangement, bubble formation and movement, arc extinguishing capacity of the media, difficulty in corona formation, and the distance between electrodes. The bubble formation and flow separation phenomena were identified for $LSF_6$. It provides fundamental data not only for $SF_6$ gas useless equipment but also for electric insulation design of high-temperature superconductor and cryogenic equipment machinery, which will be developed in future studies.

• Journal of the Korean institute of surface engineering
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• v.53 no.3
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• pp.95-103
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• 2020

In this study, the material used in the hot dip galvanizing equipment was poorly corrosion-resistant, so it was performed to solve the cost and time problems caused by equipment replacement. The theoretical calculation was performed using the DV-Xα method(Discrete Variational Local-density approximation method). The alloy (STS4XX series) of the equipment currently used has a martensite phase. Therefore, the theoretical calculation was performed by applying P4 / mmm, which is a tetragonal structure. The new alloy was chosen by designing theoretical values close to existing materials. Considering elements that contribute to corrosion, most have high prices. Therefore, the design was completed by adjusting the content using only the components of the reference material in the theoretical design. The final design alloys were chosen as D6 and D9. Designed D6 and D9 were dissolved and prepared using an induction furnace. After the heat treatment process was completed, the corrosion rate of the alloys was confirmed by using the potentiodynamic polarization test. The surface of the prepared alloys were processed horizontally and then polished to # 1200 using sand paper to perform potentiodynamic polarization test. Domestic products: 4.735 mpy (mils / year), D6: 0.9166 mpy, D9: 0.3372 mpy, alloys designed than domestic products had a lower corrosion rate. Therefore, the designed alloy was expected to have better erosion resistance.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.60-61
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• 2013

One of the most important indicators for measuring service level and productivity of the port may be a demurrage rate. Currently, in the case of grain terminal of Busan North Port, demurrage rate are recognized at a very high level, in order to improve this, it is tilted more effort operational. In order to reduce the demurrage, there is a way expansion of facility of hardware, such as the replacement of aging equipment, and how manipulative assignment rules of the apparatus of the operation on the software side, such as changing the order of facility allocation. If the financial reasons are out of question, it is possible to expand to reduce the demurrage rate by operational way. Therefore this paper deals with how to operate some of the allocation rules and silo allocation rules of equipment to reduce the work hours with model and how to operate basic equipment and grain terminal of Busan North Port want to be seen by comparative analysis.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.2
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• pp.97-103
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• 2017

Thermal imaging is mainly used in military equipment required for night observation. In particular, technologies of uncooled thermal imaging detectors are being developed as applied to low-cost night observation system. Many system integrators require different specifications of the uncooled thermal imaging camera but their development time is short. In this approach, EOSYSTEM has developed a small size, TEC-less uncooled thermal imaging camera module with $32{\times}32mm$ size and low power consumption. Both domestic detector and import detector are applied to the EOSYSTEM's thermal imaging camera module. The camera module contains efficient infrared image processing algorithms including : Temperature compensation non-uniformity correction, Bad/Dead pixel replacement, Column noise removal, Contrast/Edge enhancement algorithms providing stable and low residual non-uniformity infrared image.

• Computers and Concrete
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• v.19 no.6
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• pp.609-615
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• 2017

In this paper, the effects of elevated temperatures on the strength and compressive stress-strain curve (SSC) of recycled coarse aggregate concrete with different replacement percentages are presented. 90 recycled coarse aggregate concrete prisms are heated up to 20, 200, 400, 600, $800^{\circ}C$. The results show that the compressive strength, split tensile strength, elastic modulus of recycled aggregate concrete specimens decline significantly as the temperature rise. While the peak strain increase of recycled aggregate concrete specimens as the temperature rise. Compared to the experimental curves, the proposed stress-strain relations for recycled aggregate concrete after exposure elevated temperatures can be used in practical engineering applications.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.266-268
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• 1997

High Voltage High Current Pulsed Electric Fields (HVHC-PEF) is a promising technology for the non-thermal pasteurization of foods and a sound complement or replacement to traditional thermal pasteurization, which inactivates bacteria and other microorganisms harmful to humans, but also degrades color, flavor, texture and nutrients. Foods can be pasteurized with pulsed electric fields at ambient or refrigerated temperatures for a short treatment time of seconds or less and the fresh-like quality of food is preserved. Although successful is laboratory tests, applying HVHC-PEF to food pasteurization on a large scale presents many unresolved engineering problems. In this paper the design considerations for 25kV 1kA class HVHC-PEF pasteurization equipment are anlyzed and experimental results are discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1380-1385
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• 2009

This paper was studied about the aging judgment method by ultraviolet rays image to happen in electric power equipment using ultraviolet rays camera. We established the aging judgment method as follows; 20% within of risk factor of insulation state of electrical facility that ultraviolet rays image does not show is "good or recognition". 30$^{\sim}$50% within of risk factor is "check", 50$^{\sim}$60% within of risk factor is "inspection" and 60% above of risk factor is "replacement". This method will be utilized for the inspection about electrical facilities.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.5
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• pp.675-682
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• 2013

Reliability analysis and prediction of next failure time is critical to sustain weapon systems, concerning scheduled maintenance, spare parts replacement and maintenance interventions, etc. Since 1981, many methodology derived from various probabilistic and statistical theories has been suggested to do that activity. Nowadays, many A.I. tools have been used to support these predictions. Support Vector Regression(SVR) is a nonlinear regression technique extended from support vector machine. SVR can fit data flexibly and it has a wide variety of applications. This paper utilizes SVM and SVR with combining time series to predict the next failure time based on historical failure data. A numerical case using failure data from the military equipment is presented to demonstrate the performance of the proposed approach. Finally, the proposed approach is proved meaningful to predict next failure point and to estimate instantaneous failure rate and MTBF.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.149-156
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• 2014

Generator of hydroelectric generating unit is to be protected by the digital protection IED. Now, any IED of large capacity for hydro power plant was not developed by domestic technology. This is because it is required for the generator of the high reliability technology and considered as due to the sale of the market of IED device is small. However, the protection IED must be develop by domestic technology to meet the advanced needs of the construction and replacement of electrical equipment in accordance with the new power plant development. In this paper, a digital algorithms for protection IED of large size of hydroelectric generating unit were designed. The algorithms consist of the stator protection, anti-motoring, overexcitation and loss of excitation. The performance of the algorithms were evaluated by using the simulation data collected from the PSCAD/EMTDC software. From test results, it can be seen that the developed algorithms were not maloperation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.3
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• pp.27-32
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• 2010

The inundation of substation and ground power equipment breaks out every summer season in low-lying downtown areas and low-lying shores by torrential rain, typhoons and tsunamis. It has, in turn, caused replacement, social and economic costs for blackouts. For activity management regarding flood damage we produced a flood protection system which using the Pad transformer as a basic frame and is developed using pneumatic pressure. We tested safety concerns including insulation resistance and current leakage first for water tank flooding and, second, by an empirical test through supplying 22.9[kV]. We estimate that costs associated with flooding and power failure can be diminished by these advances toward creating a more reliable system.