• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.234-240
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• 2017

In this study, the influences of rail surface roughness on dynamic wheel-rail forces currently employed in conventional lines were assessed by performing field measurements according to grinding of rail surface roughness. The influence of the grinding effect was evaluated using a previous empirical prediction model for dynamic wheel-rail forces; model includes first-order derivatives of QI (Quality Index) and vehicle velocity. The theoretical dynamic wheel-rail force determined using the previous prediction equation was analyzed using the QI, which decreased due to rail grinding as determined through field measurements. At a constant track support stiffness, an increase in the QI caused an increase in dynamic wheel-rail forces. Further, it can be inferred that the results of dynamic wheel-rail analysis obtained using the measured data, such as the variation of QI due to rail grinding, can be used to predict the peak dynamic forces. Therefore, it is obvious that the optimum amount of rail grinding can be determined by considering the QI, that was regarding an operation characteristics of the target track (vehicle velocity and wheel load).

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.125-135
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• 2015

The tendency of more longer span length being required economical in railway bridges is studying about PSC I shaped girder. In this case, it is important to analyze and choose the effective girder section for stiffness of bridge. This study investigates the dynamic properties and safety of PSC I shaped girder being used wide upper flange whose selection based on radii and efficiency factor of flexure for railway bridge in different span type. In addition, 40m PSC Box girder bridge adopted in Honam high speed railway is further analyzed to compare dynamic performance of PSC I shaped girder railway bridge with same span length. Time history response is acquired based on the mode superposition method. Static analysis is also analyzed using standard train load combined with the impact factor. Consequently, the result met limit values in every case including vertical displacement, acceleration and distort.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.3
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• pp.310-317
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• 2014

The Next-generation High-speed Rail Technology Development Project was started in 2007 by the Korean Government with the aim of developing the core technologies for a high-speed electric multiple unit (EMU) railway system. This is the first attempt to develop a high-speed EMU railway. High-speed EMU trains have superior acceleration and deceleration compared to push-pull high-speed railways such as KTX(Korean Train eXpress). A prototype train was developed and tested on a high-speed line starting in 2012. The new train must maintain running safety during the test. Generally, the international standard (UIC518) is adopted to evaluate the running safety of trains. This method suggests that the test zone must have over 25 sections, and the length of each section must be 500 m. However, it is difficult to implement these test conditions for a real high-speed line. In this study, we analyzed the running safety using several test section lengths (100 m to 500 m) and compared the results. The results of this study will be used to establish a running safety evaluation method for high-speed EMU railways.

• The Inventors News
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• no.51
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• pp.1-16
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• 2006

함께 즐기는 '여성 발명인 축제'열린다/이 가을을 여성 발명의 계절로/빠진 영구치, 임플란트 기술로 대신한다/국내 의약품 특허출원 외국 기업이 주도/웰빙 붐 타고 기능성 베개 출원 늘어나/토양오염 복원기술, 관심 높아져/기업 CI교체 따른 상표출원 급증/여성경제단체, 오세훈 서울 시장 초청 간담회 가져/'2006대한민국 발명특허대전' 개최/특허청, 중소기업 특허경영 지원단 발족/한국특허문헌, WIPO로 전세계 서비스 실시/APEC 여성지도자네트워크 회의 개최/'2006 특허기술 사업화 성공사례발표회'/세계최초 신개념 CTF기술 상용화/특허청, 제4회 발명 장학생 선발/김치, 러시아 모스크바에 진출한다/고속 주행 틸팅열차 특허로 인정/현직 공무원, 다양한 발명품으로 특허와 되다/자신만의 'TV채널' 선택 가능하다/전지산업, 이온성 액체 관련 특허로 안전하게/명확한 의견 제출로 효율적인 심판 진행/치매예방물질 2배인 김치 개발됐다/한국과학기술연구원 논문 특허심의제도 도입/'한국 오시면 KISS로 맞이합니다'/삼성전자, 중국 특허 마쓰시타 아성 깨다/싱가포르 수출 인큐베이터로 중소기업 해외시장 공략/특허청, 영남대와 지식재산역량 강화 위한 약정 체결/깎는 횟수 줄인 잔디, 세계최초 개발/순창군, 웰빙 고추장 특허출원/역사 속의 발명품/하루 10분 발명교실/특허Q&A/케이제이알텍(주)문승자 대표/한.일 변리사회 업무협정체결 25주년 기념식 개최/중소기업청, 하반기 18조원 신용보증 공급 계획/'2006 대만 국제발명품 전시회'서 한국 참가자 수상/'불났을 때' 긴급 대피 요령은?/아이디어 착상 및 발명 기법/창의성과 도전정신이 성공한 사업가 만든다/사탕을 탄생시킨 사람들/'휴대폰 특허료 1.3억불 내라' 중재 결정/'신발깔창 휴대폰 충전기'/휴대폰으로 광고 받고 무료 문자 이용 가능/아파트 저작권.특허 열풍 거세게 불어/'골다공증 예방 요구르트' 나왔다/갈증 느끼지 않아도 '물' 자주 마셔라/10월 '지재권 및 여성발명 창의교실' 개최안내/한국여성발명협회 회원사 발명품 가이드/함씨네토종콩종합식품, 특선 수상/

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.8
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• pp.941-949
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• 2011

When a railway vehicle passes through curves & transitions, the running speed must be improved by setting limits on the maximum running speed in each section of the conventional line(Dongdaegoo-Namsunghyun) considering derailment safety. Our goal is to improve the maximum running speed of railway vehicle that passes through curves & transitions where there is a high risk of derailment. We examined the influence on the derailment safety when the railway vehicle passes through curves of actual track conditions (Dongdaegoo-Namsunghyun up and down lines). We performed the derailment safety analysis by increasing the running speed on curve radius by 5%.20% compared to existing speed under actual track conditions.

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.589-594
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• 2010

Superimposition of horizontal and vertical curves may hamper the ride comfort and running stability of train and largely affect the maintenance costs. However, in many cases, it is not easy to make a track alignment plan because of the geographic conditions or undesirable environmental factors. In this paper, a comparative study on the effect of superimposition of vertical and horizontal curve on the ride comfort and optimum horizontal curve conditions was performed. That is, optimal cant and ride comfort analysis with and without a vertical curve superimposed on the horizontal curve were evaluated. Also the superimposition effect on ride comfort and alignment conditions in high speed zone were evaluated. From the analysis results, it was found that the ride comfort is similar to that at the only horizontal curves when applying the compensation cant for the superimposed site.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4532-4541
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• 2013

With speed up of railway, the demand for safety of the railroad transportation is on the increase in Korea's conventional railways. In additions, freight trains with heavier axle load are required to run conventional railways. In order to solve these requirements, the increase of rail weight and the application of long rail system have been underway in conventional railways. However, the research on ties that is absolutely influencing the track stiffness in ballasted tracks has not been much progress. In this paper, the new H-typed tie is developed to increase the track stiffness and reduce the track irregularity. And from the structural analysis by FE program, the intial design drawing of the new H-typed tie is proposed.

• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.251-259
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• 2014

The transition zone between an earthwork and a bridge effect to the vehicle's running stability because support stiffness of the roadbed is suddenly changed. The design criteria for the transition structure on ballast track were not particular in the past. However with the introduction of concrete track is introduced, it requires there is a higher performance level required because of maintenance and running stability. In this present paper, a transition structure reinforced with geosynthetics is suggested to improve the performance of existing bridge-earthwork transition structures. The suggested transition structure, in which there is reinforcing of the approach block using high-tension geosynthetics, has a structure similar to that of earth reinforced abutments. The utilized backfill materials are cement treated soil and gravel. These materials are used to reduce water intrusion into the approach block and to increase the recycling of surplus earth materials. An experiment was performed under the same conditions in order to allow a comparison of this new structure with the existing transition structure. Evaluation items are elastic displacement, cumulative settlement, and earth pressure. As for the results of the real-scale accelerated testing, the suggested transition structure has excellent performance for the reduction of earth pressure and settlement. Above all, it has high resistance the variation of the water content.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.223-231
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• 2018

Recently, due to various environmental problems, blast tracks in tunnel are replaced with concrete tracks, but they have more adverse effects on noise than blast tracks so that additional noise measures are needed. Among these measures, sound-absorbing blocks start to be used due to its easy and quick installation. However, the performance of sound absorption blocks need to be verified under real environmental and operational conditions. In this paper, interior noise levels in KTX train cruising in Dalseong tunnel are measured before and after the installation of sound-absorbing blocks and the measured data are analyzed and compared. Additionally, noise reduction are estimated by modeling the high speed train, the tunnel and absorption blocks. Measurement devices and methods are used according to ISO 3381 and the equivalent sound pressure levels during the cruising time inside the tunnel are computed. In addition to overall SPLs(Sound Pressure Levels), 1/3-octave-band levels are also analyzed to account for the frequency characteristics of sound absorption and equipment noise in a cabin. In addition, to consider the effects of train cruising speeds and environmental conditions on the measurements, the measured data are corrected by using those measured during the train-passing through the tunnels located before and behind the Dalseong tunnel. Analysis of measured results showed that the maximum noise reduction of 6.8 dB (A) can be achieved for the local region where the sound-absorbing blocks are installed. Finally, through the comparison of predicted 1/3-octave band SPLs for the KTX interior noise with the measurements, the understanding of noise reduction mechanism due to sound-absorbing blocks is enhanced.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.40-51
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• 2020

Much time has passed since Korea's expressway congestion-threshold speed was revised in 2011. In the meantime, various expressway environments have changed owing to improved performance of vehicles, expanded operations of transport competition (i.e., the KTX), and increased speed limits along some expressway sections. In addition, the speed that expressway users expect to travel at is also increasing. Therefore, through a survey, this study investigates expressway users' perceptions of congestion, and reviews the adjustment of the expressway speed congestion threshold by analyzing expressway traffic flow. One result of the survey confirms that the threshold speed expressway users consider to be congestion has slightly increased. Analyzing traffic and speed data through a K-means algorithm found that the threshold speed for congestion is 60 km/h. In addition, assuming the congestion threshold speed increase from 40 km/h to 50 km/h and 60 km/h, frequently congested expressway sections are identified, determining that 50 km/h is appropriate as a congestion threshold for proper expressway mobility management.