• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.82-83
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• 2008

In the cases of high speed railway bridge, dynamic behavior analysis is important because of high passing velocity and moving load at the regular intervals, and the damping ratio is a major element in dynamic behavior analysis. In this paper, damping ratios were estimated by two methods and vibration type sections, and relationship between estimated damping ratio and representative value of bridge vibration. At the results, estimated damping ratio using all time of vibration were more stable then using only free vibration section. And in the case of using extended Kalman filter, estimated damping ratio were trend of growth by growth of representative value of bridge vibration. At last, it was shown that study about reliabilities of estimated damping ratios were need.

• 한국산업융합학회 논문집
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• 제4권2호
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• pp.199-205
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• 2001

With the growth of BiCMOS technology in ASIC design, the issue of analyzing fault characteristics and testing techniques for BiCMOS circuits become more important In this paper, we analyze the fault models and characteristics of high speed full-swing BiCMOS circuits and the DFT technique to enhance the testability of full-swing high speed BiCMOS circuits is discussed. The SPICE simulation is used to analyze faults characteristics and to confirm the validity of DFT technique.

• 한국철도학회논문집
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• 제9권5호
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• pp.606-611
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• 2006

This paper presents a procedure and an analysis method to evaluate reliability of the Korea high-speed train. The rolling stock system is divided into 6 sub-systems and each subsystem is classified into sub-assemblies. Functional analysis has been conducted to draw reliability block diagrams for the sub-systems. First, failure rates has been calculated for each sub-assembly from the failure data obtained during commissioning tests. Then a reliability block diagram is used to evaluate the MKBF(Mean Kilometers Before Failure) of the sub-systems. Activities to increase reliability have been carried out throughout the test runs and analysis results show that the reliability of the rolling stock system is gradually growing in time.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.483-488
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• 2003

Frictional heating in brakes causes thermoelastic distortion of the contacting bodies and hence affects the contact pressure distribution. The resulting thermo-mechanical coupling can cause thermoelastic instability (TEI) if the sliding speed is sufficiently high, leading to non-uniform heating called hot spots and low frequency vibration known as hot judder. The vibration of brakes to the known phenomenon of frictionally-excited thermoelastic instability is estimated studying the interface temperature and pressure evolution with time. A simple model has been considered where a layer with half-thickness ${\alpha}$ slides with speed V between two half-planes which are rigid and non-conducting. The advantage of this properly simple model permits us to deduce analytically the critical conditions for the onset of instability, which is the relation between the critical speed and the growth rate of the interface temperature and pressure. Symmetrical component of pressure and temperature distribution at the layer interfaces can be more unstable than antisymmetrical component. As the thickness ${\alpha}$ reduces, the system becomes more apt to thermoelastic instability. Moreover, the evolution of the system beyond the critical conditions has shown that even if low frequency perturbations are associated with low critical speed, it might be less critical than high frequency perturbations if the working sliding speed is much larger than the actual critical speed of the system.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.373-382
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• 1999

Nucleation and growth process of sticking particle in ferritic stainless steels was investigated using a two disk type hot rolling simulator. The sticking behavior was strongly dependent on the surface roughness of a high speed steel roll(HSS) and the oxidation resistance of the ferritic stainless steels. A hot rolling condition with the lower oxidation resistance of the stainless steel and the higher surface roughness of HSS roll was more sensitive to sticking occurrence. It was also illucidated that the initial sticking particles were nucleated at the scratches formed on the roll surface and were served as the sticking growth sites. As rolling proceeded, the sticking particles grew sites. As rolling proceeded, the sticking particles grew by the process that the previous sticking particles provided the sticking growth sites.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1738-1743
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• 2007

The newly established high speed railway station may function not only just as a traffic convergence but also as an energizing force with multiple roles in the context of municipal environment. As a result, the development of high speed railway station zone will be considered as great opportunities as well to enhance quality of life of the neighboring inhabitants, as to develop new footholds for the inner-municipal growth and mobilization. The main purpose of this article is to offer guidelines about the effects of development of the high speed railway station zone seen from multiple aspects of municipal lifes and functions. To attain this purpose, the definition of high speed railway station zone, its characteristics, and its roles will be handled with the case of advanced countries such as Japan and France. And some lessons will be proposed based on them.

• 지역연구
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• 제35권4호
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• pp.19-32
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• 2019

2000년대 이후 중국정부는 전 국토를 연결하는 '4+4 8대 간선'을 건설하여 상대적으로 낙후된 중·서부지역을 발전시키고 지역 간 격차를 해소하고자 하였다. 일반적으로 고속철도는 지역 간 접근성을 향상시켜 지역경제발전에 긍정적인 영향을 미치는 것으로 알려져 있다. 하지만, 일부 연구에서는 고속철도 건설로 인해 지역 간 불균형이 확대될 수 있음을 지적하기도 한다. 이에 본 연구는 베타수렴모형(beta-convergence model)을 통해 고속철도가 중국의 지역경제성장과 균형발전에 미치는 영향에 대한 실증분석을 수행하였다. 특히, 지역의 발전수준에 따라 고속철도의 효과가 어떻게 달라지는지에 초점을 맞추었다. 이를 위하여 지역발전 수준이 서로 다른 동·중·서부 지역을 연결하는 호용선(Shanghai-Chengdu)을 중심으로 분석을 수행하였다.

• 한국태양에너지학회 논문집
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• 제30권5호
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• pp.93-99
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• 2010

Nucleate pool boiling experiments with constant heat flux condition were performed using pure R113 for various channel heights under saturated pool condition. A circular heater of 1mm diameter, with artificial cavity in the center, fabricated using MEMS technique and the high-speed controller were used to maintain the constant heat flux. Images of bubble growth were taken at 5,000 frames per second using a high-speed CCD camera. The bubble geometry was obtained from the captured bubble images. The effects of channel height on the bubble growth behaviors were analyzed as dimensional scales for the initial and thermal growth regions. The parameters for the bubble growth behaviors were bubble radius, bubble growth rate, and bubble shapes. These phenomena require further analysis for various surface angles, but this study will provide good experimental data with constant heat flux boundary condition for such works.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1980-1992
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• 2006

Nucleate pool boiling experiments were performed using pure R11 for various surface angles under constant heat flux conditions during saturated pool boiling. A 1-mm-diameter circular heater with an artificial cavity in the center that was fabricated using a MEMS technique and a high-speed controller were used to maintain the constant heat flux. Bubble growth images were taken at 5000 frames per second using a high-speed CCD camera. The bubble geometry was obtained from the captured bubble images. The effects of the surface angle on the bubble growth behavior were analyzed for the initial and thermal growth regions using dimensional scales. The parameters that affected the bubble growth behavior were the bubble radius, bubble growth rate, sliding velocity, bubble shape, and advancing and receding contact angles. These phenomena require further analysis for various surface angles and the obtained constant heat flux data provide a good foundation for such future work.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.761-767
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• 2011

Since the "Low Carbon, Green Growth" as a social requirements is attracted public attention, the policies and investments of the railway which have been less estimated than road is re-considered. Since the starting the commercial service (2004. April), the KTX have been operated successfully while transport passengers over 100million for years. And also the project for development of KHST (Korea High Speed Train ; G7) had been accomplished with a good result, the first trainset of KTX-II which base on G7 project was manufactured and testing now. On the other hand, the world's technology of the high speed train is more faster, and changing to a distributed traction system. To catch up the world's leading technology, the HEMU(High-speed Electric Multiple Unit) project will secure new technology and aims to promote the technology of domestic high-speed train. The authors indicates the result of detail review such as a curve, slope of the track and electrical dead section of the catenary to test at 400kph and also the performance simulation of the developed rolling stock in this paper. As the result, the authors devise the test scenario to perform a maximum speed test (stability at max. speed, acceleration & deceleration etc) with the restricted conditions such as track length, track available time etc by considering above result.