• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.219-222
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• 2007

The Full-Off Fitting of Movable Bracket using conventional line have received a dynamic contact impact between contact wire and pantograph of electric rolling stock, so this impact cause a rapid vibration of foreword and back near the supporting point of movable bracket. The Full-Off Fitting on Movable Bracket in conventional line differs from that in high speed line. Now conventional line have required a speed up for new electric locomotive and electric car. In speed-up track and big impact place, the Full-Off Fitting and the dropper often get demage. We have done a study of buffering function to solve that problem in conventional line. We have find a need adopting buffer fitting. It is decrease a dynamic impact between contact wire and pantograph of electric rolling stock.

• Journal of Electrical Engineering and Technology
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• 제4권4호
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• pp.485-491
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• 2009

The importance of renewable energy sources has been growing at a high rate as a result of being environment friendly. In particular, wind power is one of the most successfully utilized of such sources to produce electrical energy. Because of the randomness of wind speed, the reliability impact on this highly variable energy power is important aspect that needs to be assessed. In this paper, the impact on the reliability indices of wind speed correlation between two farms is considered.

• 한국가시화정보학회지
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• 제9권1호
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• pp.55-60
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• 2011

Pulsed supersonic liquid jets injected into an ambient air are empirically studied by using a high pressure ballistic range system. Ballistic range systems which are configured with high-pressure tube, pump tube, launch tube and liquid storage nozzle. Experimental studies are conducted to use with various impact nozzle geometry. Supersonic liquid jets are generated by an impact of high speed of the projectile. High speed liquid jets are injected with M = 3.2 which pressure is 1.19 GPa. Multiple jets which accompany with shock wave and pressure wave in front of the jet were observed. The shock-wave affects significantly atomization process for each spray droplets. As decreasing orifice diameter, the averaged SMD of spray jets had the decreasing tendency.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1213-1220
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• 2008

In this study, the crashworthy design guidelines for the high speed EMU were derived and numerically evaluated. As for this high speed train, there are several different features from the KTX in that the conventional type bogies are adopted and the front end car (TC car) accommodates passengers. It is natural that the impact acceleration of the front end car should be controlled under the appropriate level stipulated at safety regulations for collision accidents. Also, car-to-car interfacing structures and devices should be deliberately designed to prevent overriding and telescoping mechanisms. As the first step for these design countermeasures, it was studied that how much impact energy should be absorbed at the energy absorbing zones and devices of each carbody to satisfy the impact acceleration regulations of the safety regulations. These results will be used as the crashworthy design guidelines for the high speed train in the next year research.

• 한국생산제조학회지
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• 제20권2호
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• pp.169-173
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• 2011

Crash box is introduced to vehicle design to improve the impact performance and reduce the damage of vehicle body at impact speed. The crash box behind bumper can absorb impact energy effectively to improve vehicle safety. Repair cost at collision accident can be cut down by use of this box. The configuration of car body must be designed by considering the characteristic of material due to the deformation of car body happened at impact. Many papers have been published about material of crash box all over the world. The study of crash box with tube expansion type has been going on Korea. This study is done by the simulation analysis about front collisions against 5 kinds of aluminum crash boxes with the basic structure of square section.

• 한국분무공학회지
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• 제17권2호
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• pp.86-93
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• 2012

The effects of projectile impact system on the transient spray characteristic which is supersonic liquid tip velocity were studied by experimentally. Supersonic liquid jets were generated by impact of a high speed projectile driven by a Two-stage light gas gun. A high speed camera and schlieren optical system were used to capture the spray structures of the supersonic liquid jets. In a case of nozzle assembly Type-A, expansion gases accelerate a projectile which has a mass of 6 grams from 250 m/s at the exit of the launch tube. Accelerated projectile collides with the liquid storage part, then supersonic liquid jets are injected with instantaneous spray tip velocity from 617.78 m/s to 982.54 m/s with various nozzle L/d. However, In a case of nozzle assembly Type-B which has a heavier projectile (60 grams) and lower impact velocity (182 m/s), an impact pressure was decreased. Thus the liquid jet injected at 210 m/s of the maximum velocity did not penetrate a shock wave and fast break-up was occurred. Pulsed injection of liquid column generated second shock wave and multiple shock wave.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.29-34
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• 2005

141,841 car-to-car collision had occurred in 2003, and among the accidents 51,796 were rear-end impact. According to insurance company for loss or damage, more than $60\%$ of rear-end impact victims suffer neck injury. This means at least 31,000 neck injury victims have happened in 2003. More than $97\%$ of the neck injury victims have low severity injury than A.I.S 2. Head restraint, which is designed to limit rearward head movement and equipped on seat, can considerably protect neck from rear-end impact. In this paper we evaluated head restraint geometry and drivers' sitting position according to RCAR standard and carried out low speed volunteer crash test. The crash speed is 4km/h and N.I.C value is used to determine injury probability. Through these research results we can introduce the method to prevent neck injury at rear-end impact.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.96-100
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• 2002

The purpose of this paper is presented a rational method of predicting dynamic/impact tensile strength of high tensile steel materials widely used fur structural material of automobiles. It is known that the ultimate strength is related with the loading speed and the Lethargy Coefficient from the tensile test. The Dynamic Lethargy Coefficient is proportional to the disorientation of the molecular structure and indicates the magnitude of defects resulting from the probability of breaking the bonds responsible for its strength. The coefficient is obtained from the simple tensile test such as failure time and stresses at fracture. These factors not only affect the static strength but also have a great influence on the dynamic/impact characteristics of the joist and the adjacent structures. This strength is used to analyze the failure life prediction of mechanical system by virtue of its material fracture. The impact tensile test is performed to evaluate the life parameters due to loading speed with the proposed method. Also the evaluation of the dynamic/impact effect on the material tensile strength characteristics is compared with the result of Campbell-Cooper equation to verify the proposed method.

• 한국표면공학회지
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• 제35권4호
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• pp.199-205
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• 2002

TiN and TiAlN films were deposited on SKD 11 steel substrates by an arc ion plating (AIP) technique. The crystallinity and morphology for the deposited films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties of both films were investigated through the indentation, impact, and wear test. Those films fairly adherent to SKD 11 steel substrate, showed hardness values of 2300 $\pm$ 100kg/$\textrm{mm}^2$ and 3200 $\pm$ 100kg/$\textrm{mm}^2$ with a load of 25g, respectively. During impact test, TiAlN films showed much superior impact wear resistance to TiN films. It could be suggested that the TiN films was failed relatively by plastic deformation with oxidation during impact test, while TiAlN films was failed by brittle fracture and resisted the oxidation by the impact energy. The friction coefficient of TiAlN films became lower than that of TiN films at high sliding speed condition although it was higher than that of TiN films at low speed. Therefore, TiAlN films was suggested to be more advantageous than TiN films for high speed machining fields.

• 한국정밀공학회지
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• 제22권11호
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• pp.38-44
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• 2005