• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.322-327
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• 2020

An Armor Piercing Fin Stabilized Discarding Sabot (APFSDS), which penetrates and sabotages the target by physical energy, consists of a general penetrator using Depleted Uranium (DU) or Tungsten Heavy Alloy (THA) but THA is preferable because of manufacturing and environmental issues. On a THA penetrator, the penetration performance is determined mainly by self-sharpening depending on the hardness and toughness of materials. In particular, the tensile strength and impact strength work as key factors. The correlation coefficient for the penetration performance of the tensile strength was 0.721 and the impact strength was -0.599. The improved penetration performance by additional heat treatment was proven experimentally. Therefore, maintaining elongation over 9 % and tensile strength over 123 kg/㎟ is desirable, and the impact strength should be less than 6.8 kg·m/㎠ for good penetration performance.

• Journal of Aquaculture
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• v.17 no.2
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• pp.139-143
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• 2004

In the fish oil forced oxidized at 6$0^{\circ}C$ for 10 days, changes in the levels of peroxide (POV), anisidine (AnV), total oxidation (Totox), iodine (IV), acid (AV) and fatty acids composition were measured. The levels of POV, AnV and Totox remained unchanged or decreased after reaching the maximum. The concentrations of polyunsaturated fatty acids (PUFA) such as Docosa hexaenoic acid (DHA) or Eicosa pentaenoic acid (EPA) decreased with extended oxidation of fish oil. In saturated fatty acids (SFA) like C16:0, their concentration increased with decreasing PUFA. The ratios of PUFA/SFA and DHA/C16:0 decreased with extended oxidation of fish oil. Using a single parameter of POV, AnV, Totox, AV, IV, or fatty acids for evaluation of the quality of fish oil may prove difficult. Besides other parameters, the ratios of PUFA/SFA and/or DHA/C16:0 could be a good index to evaluate the quality of fish oil.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.1110-1116
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• 2017

Depending on the operating characteristics, track circuit is installed for the purpose of direct or indirect control of the signal device, point switch machine and other security device. These are mainly used for train detection, transmission of information, broken rail detection and transmission of return current. Especially, the return current is related to signal system, power system and catenary line, and track circuit systems. It is one of the most important component shall be dealt for the safety of track side staff and for the protection of railway-related electrical system according to electrification. Therefore, an accurate analysis of the return current is needed to prevent the return current unbalance and the system induced disorder and failure due to an over current condition. Also, if the malfunction occurred by the return current harmonics, it can cause problems including train operation interruption. In this paper, we presented measurement and analysis method at return current and it's harmonics by high speed train operation on the honam high speed line.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.431-437
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• 2017

In this study, based on the RPS algorithm, the application results to an electrically controlled suspension system using previewed road information are presented. Reducing the excessive vibration induced by a disturbance transmitted to the system and secure its stability is a major issue. In particular, in the automotive industry, the demand is constantly being raised. A typical external disturbance causing vibration and instability of a vehicle is an irregular roadway surface that contacts a running vehicle tire. Therefore, obtaining such profile information is an important process. The RPS algorithm using a multi sensor system was constructed and implemented in a real car. Through experimental work using the RPS system included non-contact type optical sensors, it could robustly reconstruct the road input profiles from the intermixed data onto the vehicle's dynamic motion while traveling at an uneven roadway surface. A controller with a preview control was designed in the framework of a semi-active suspension system based on the 7 degrees of freedom full vehicle model. The control performance of the system was evaluated through simulations and the results were compared with the passive vehicle condition. These results highlight the feasibility of the presented control frame.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.220-229
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• 2004

The AC railway system is quite differing from the general electric power system because it is single- phase and intermittently heavy loads. Thus, inevitably power quality problems are occurred in the AC railway system, i.e. voltage regulation voltage sags, voltage imbalance, and harmonic distortion. Recently, the power quality of the AC railway system becoming a hot issue because it is affect the control and safety of high-speed traction. In addition it is also affect the power quality of the electric power system. In this paper, single-phase Unified Power Quality Conditioner(UPQS) for the AC railway system is proposed to compensate the voltage sags and harmonic distortion. The configurations and control schemes of the proposed single-phase UPQC are presented. The effectiveness of the proposed single-phase UPQC application is verified by the PSCAD/EMTDC simulation works. It can be shown that the application of UPQC in the AC railway system is very useful to compensate the voltage sags and harmonic distortion from the results of related simulation works.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.692-700
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• 2007

A trial run of locally-developed tilting train has been in process on Chungbuk line since the test vehicle was first produced. For the system stabilization, interface verification among the systems including track, structure, catenary and signaling system, not to mention the rolling stock, is very crucial. In the area of wayside structure, the stability of track structure and train run shall be evaluated through the review of impact by increased speed by developed train on track structure. The study thus was intended to evaluate the impact on track while a tilting train is running the curve section, which is vulnerable to accelerated train speed. The analysis of tilting train test running the part of Chungbuk line and Honam line was conducted to identify the impact on existing track performance by tilting train. To identify the movement behavior of each part of track while tilting train, high speed train and traditional train (Mugunghwa and freight train) were running the existing line, wheel load, lateral wheel load, rail bending stress, vertical and lateral displacement of rail and vertical displacement of sleeper were compared and analyzed so as to evaluate the expected impact by tilting train for improving the train speed.