• Proceedings of the KSR Conference
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• 2004.10a
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• pp.763-768
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• 2004

CWR(Continuous Welded Rail) has many advantage over the conventional jointed rail track. The use of CWR track not only reduces the track maintenance cost, but increase the life cycle of track components. As the use of CWR increases in track structures, derailing disasters associating with track buckling also increase in great numbers due to high compressive thermal stress. Despite the importance, the number of studies relevant to the instability is quite limited. In this paper, It considers the contribution of rail-pad-fastener resistance, uplift of tie and nonlinear analysis. Influence of various track components on CWR track temperature and mode shape were characterized.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.68-69
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• 2011

마그네슘 판재의 온간 스프링백 거동 예측을 위한 재료 거동 모델을 고찰하였다. V-굽힘 시험에 관한 기존 문헌의 결과와 비교하여 재료 모델의 타당성을 토하였다. 스프링백 거동의 정량화를 위해 온간 S-rail 프레스금형에 의한 성형 시험을 수행하였다. 성형 시험은 다양한 온도, 속도, 성형깊이 조건에서 수행하였으며 시험 결과를 서로 비교하였다. 재료 모델을 사용하여 S-레일 성형에 따른 스프링백 예측을 위한 유한요소해석을 수행하고 그 결과를 시험 측정값과 비교하였다. 이로부터 재료 모델의 한계와 가능성을 고찰하였다.

• Annual Conference of KIPS
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• 2014.11a
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• pp.33-36
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• 2014

철도로 인한 소음 문제는 최근 국민의 정온한 환경에 대한 권리의식 증대와 삶의 질에 대한 높은 관심으로 철도 소음에 대한 민원이 급증하여 지역 갈등을 초래하고 막대한 사회적 비용 부담으로 철도 산업을 저해하는 요소이다. 이에 따라, 철로 부근의 진동 및 소음에 대한 모니터링 시스템의 필요성이 증대되고 있으나, 레일의 조도상태 및 방진재 사양 등 철도진동소음에 영향을 주는 인자를 충분히 포함하지 못하고 있으며, 측정 및 분석 데이터의 체계적인 관리, 축적 구조를 갖지 못하는 문제가 있다. 또한, 연구기관의 인위적인 데이터 양식의 사용으로 실용적이고 개방적인 구조를 갖추지 못해 실제 엔지니어링 현장에서 활용하기 어렵다. 이에, 본 논문에서는 실제 엔지니어들이 현장에서 취득하는 정보를 체계적이고 지속가능한 형태로 데이터베이스화 하는 일체의 시스템 구축에 대해 논한다.

• The Journal of the Acoustical Society of Korea
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• v.33 no.3
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• pp.191-199
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• 2014

Wave reflection and transmission characteristics in waveguides are an important issue in many engineering applications. A combined spectral element and finite element (SE/FE) method is used to investigate the effects of local non-uniformities but limited at relatively low frequencies because the SE is formulated by using a beam theory. For higher frequency applications, a method named a combined spectral super element and finite element (SSE/FE) method was presented recently, replacing spectral elements with spectral super elements. This SSE/FE approach requires a long computing time due to the coupling of SSE and FE matrices. If a local non-uniformity has a uniform cross-section along its short length, the FE part could be further replaced by SSE, which improves performance of the combined SSE/FE method in terms of the modeling effort and computing time. In this paper SSEs are combined to investigate the characteristics of waves propagating along waveguides possessing geometric non-uniformities. Two models are regarded: a rail with a local defect and a periodically ribbed plate. In the case of the rail example, firstly, the results predicted by a combined SSE/FE method are compared with those from the combined SSEs in order to justify that the combined SSEs work properly. Then the SSEs are applied to a ribbed plate which has periodically repeated non-uniformities along its length. For the ribbed plate, the propagation characteristics are investigated in terms of the propagation constant.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.10
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• pp.107-115
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• 1998

A multiplier bit-pair recoding technique derived from Booth algorithm is used as an effective method that can carry out a fast binary multiplication regardless of a sign of both multiplicand and multiplier. In this paper, we propose an implementation of an optical high-speed multiplier which consists of a symbolic substitution adder and an optical multiplication algorithm, which transforms and enhances the multiplier bit-pair recoding algorithm to be fit for optical characteristics. Specially, a symbolic substitution addition rules are coded with a dual-rail logic, and so the complement of the logic of the symbolic substitution adder is easily obtained with a shift operation because it is always present. We also construct the symbolic substitution system which makes superposition image by superimposing two shifted images in a serial connection and recognizes a reference image by feeding this superimposed image to a mask. Thus, the optical multiplier, which is compared with a typical system, is implemented to the smaller system by reducing the number of optical passive elements and the size of this system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1376-1380
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• 2005

In recent automotive industry, vehicle weight can be reduced by one-step forming of tailored blanks welded with two or more sheets of metal blanks. Tailored blank(TB) welding is a production method for blanks involving welding together materials of different quality, thickness, and coating, and has proved popular in fabrication automotive parts. This paper deals with the forming characteristics of mash seam welded tailored blanks. Using these forming characteristics, the bumper beam was developed using the mash seam welded tailored blank with the different thickness. We performed the forming simulation with respect to strain distribution on blank during the stamping of the bumper rail part. Based on these results, we made some stamping tryouts with selected types of blank designs to investigate the formability of tailored blank with different thickness. During the tryouts, we knew that it was important the BHF(Blank Holding Force). We obtained to reducing 10.5% weight and cost with adapting the bumper beam of automotive component using the tailored blank of mash seam welding.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.386-394
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• 2007

Due to the transportability problems, long rail shall be from base rail unit, which is normally 100m for regular rail and 300m for high speed rail. After these rail units are transported from the fabricator to the site, the field weld would be performed.axial stresses in the long rail is mainly from the temperature differences at various locations the long rail. Also the gaps between each welds cause secondary axial stresses in the rail. In addition to these, re-welds the fractured rails, rail buckling, irregular rail vibration, rail twist also result innonuniform axial stresses in the rail. To obtain the rail buckling stability, the rail stresses shall be released due to the resetting of CWR. Traditionally two resetting of CWR methods have been applied, the one is rail heater and the other is rail tenser. these methods, the latter has been recommended because it has less limitation in the rail length and it is easier to minimized the force differences. But even in this method, the calculation is cumbersome and is not easy to find out the rail stress distribution itself.refined methodsxial stress resetting in the long rail is studied and this study be easily applied in the real construction. From this approach, more rational rail maintenance system can be expected.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.604-609
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• 2016

This study evaluated the long-term performance of RSR (Reinforced Subgrade for Railways) technology which increases the railway line capacity without the need for additional land. Its characteristics include the use of a short reinforcement with rigid wall, which make it possible to apply it in confined spaces. The 7m high and 40m long testbed employed to evaluate the long-term performance was designed and constructed near Jupo station on the Chang-hang line. This line, located close to a local bus route, had collapsed at the subgrade following heavy rainfall. The performance of the new type of subgrade was verified with long term measurements over a 2 year period including the surface and ground settlement, horizontal displacement of the wall, tensile strain of the reinforcement, and settlement of the rail top on the side track. Based on the results of the measurements made until now, we concluded that it had sufficient safety and serviceability for use as a railway subgrade. It is expected that RSR technology could be frequently used at sites which lack the necessary construction materials for an embankment and are located close to functional railway lines and boundaries, in order to settle civil complaints.

• Journal of agriculture & life science
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• v.45 no.5
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• pp.105-113
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• 2011

This study was carried out to develop an automatic loading equipment that can load seedling trays on loading position of the seedling bed driving on enclosed-type rail installed for interconnecting each process of raising seedlings in plant factory. The experiment of transferring the seedling tray by monorail pusher was carried out to figure out the required transfer force and problems during push type device of transporting the plastic seedling trays, that has completed its sowing process, which are installed onto the board of different materials. From the results of this experiment, the loading equipment which can exactly load three of the seedling trays orderly on the loading position of the seedling bed was designed and made. When three sowed trays on every board are transferred by pusher with the speed is at 30 cm/s, the maximum peak transfer force with maximum overshooting at initial transient state and the maximum transfer force at stead state are were respectively 32.8 N, 29.4 N on rubber board, 29.7 N, 22.5 N on a wooden board, 26.9 N, 19.6 N on a acrylic board, and 27.6 N, 19.1 N on an iron board. Changes in the transfer force occurred its maximum at the moment when the pusher collided with the tray, after the collision gradually decreased until it became stable. When two or three trays placed it in order of widthwise are transferred, it is occurred the overlapping of the tray's external bracket. The developed automatic loading equipment with PLC controller did not make any operation error through 100 times of tests, its maximum seedling tray loading speed was 2 sec/tray and its maximum error of transferred location of the tray was 0.5 cm.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2090-2100
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• 2011

Railway rail fastening system is the critical device which gives big influences to not only the vehicle driving stability and the orbit's structural stability against the impulsive load, but also the noise vibration and the ride comfort. As a part of the low-carbon green growth, the importance of the railroad industry is getting highlights on its excellent energy-efficiency and eco-friendliness. However, so far the Korea's domestic rail fastening system technology is not so good and the technical reliance to abroad is very heavy. In this study, we conducted comparative analysis on the rail fastening system with new and used one of the same type. And those systems are imported by Seoul Metro and are being used by it. With this basis, we developed the components and the materials and then, established the durability assessment methods appropriate to the Korean domestic circumstances. And through the reliability qualification test on the 7 parts of the rail fastening system, we've improved the reliability and guaranteed the 15 years of service lifetime. ($B_{10}Life15$) Establishment and standardization of Reliability Standard on the parts of the rail fastening system such as anti-vibration pads, guide-plate, screw spike made it possible to perform the internationally fair assessment. And it is thought that we can satisfy the manufactures' and consumers' needs of cost-cutting and qualification security by shortening of assessment period on rail fastening system.