• 한국철도학회논문집
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• 제20권5호
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• pp.637-648
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• 2017

본 논문에서는 이전 논문에서 제시한 불연속 프리캐스트 콘크리트궤도 유한요소 해석모델과 초기 변형 및 온도 변형 분석 결과를 이용하여 초기 변형과 온도에 의한 변형이 슬래브의 응력 분포에 미치는 영향을 분석하였다. 분석 결과에 따르면 프리캐스트 콘크리트 슬래브에 이미 발생해 있는 초기 변형과 온도 경사에 의한 변형이 있는 상태에서 열차하중이 작용하는 경우에는 슬래브 중앙, 모서리 중앙, 전단포켓 코너부 등 슬래브 상부에서 최대 인장응력이 발생하게 되어 열차하중만 작용하는 경우와 매우 다른 응력 분포를 나타낸다. 따라서 불연속 프리캐스트 콘크리트 궤도의 실제 취약부의 위치와 파괴모드를 예측하기 위해서는 슬래브의 초기 변형과 온도 변형을 고려하여 열차 하중에 의한 응력을 산정해야만 한다.

• 한국정밀공학회지
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• 제32권7호
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• pp.597-602
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• 2015

In this paper, we studied the steering performance of wheelset with primary suspension characteristics of railway vehicle. We carry out dynamic analysis and experimental study for the vehicle models which are different primary suspension characteristics. The steering angle of a vehicle model (Case 1) operating in domestic subway lines is insufficient compared with an objective steering angle for curved track. And the steering angle of a vehicle model (Case 2) with improved self-steering performance of wheelset is a little improved compare to previous vehicle model. But also Case 2 model is still insufficient compared with an objective steering angle and has its limit in steering performance. So to overcome this limit of steering performance of passive type railway vehicle, an active steering technology is being developed. In case of vehicle model with active steering system, the steering performance is improved remarkably compared to passive type vehicle model.

• Journal of information and communication convergence engineering
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• 제7권4호
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• pp.551-555
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• 2009

This paper proposes a signal generation method for automatic control of a monitoring camera. Using the control signal, the monitoring camera can track a moving object and keep it near the image center for a longer time. The proposed method is estimated in the experiments that automatically move a maker located at the specified position to the image center.

• 한국의학물리학회지:의학물리
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• 제13권1호
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• pp.51-53
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• 2002

The results of the measured specific activities of Rn-222 in sewerage and drinking water of Ulaanbaatar City, Mongolia using the HP-Ge gamma-spectrometer, solid state nuclear track detector and liquid scintillator, are compared. The specific radioactivity for the Rn-222 in water of Ulaanbaatar City ranged 10-250 Bk/l, with an average of 110 Bk/l.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.487-488
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• 2007

Fault section detection and service restoration is very important in ungrounded distribution system. Techniques currently used to track down faults are time consuming and cumbersome. A new scheme is developed based on communication technology, and the simulation result shows that the method can satisfy the requirement proposed.

• 한국철도학회논문집
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• 제19권6호
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• pp.777-784
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• 2016

본 연구에서는 도시철도에 사용되는 방진체결장치가 현장에서 부담하는 하중의 체계적 평가를 통하여 방진체결장치의 성능시험하중에 대한 기준이 정립되었다. 방진체결장치가 가질 수 있는 동적 강성 범위를 알아보기 위하여 국내에서 공급 가능한 3가지 유형의 방진체결장치들에 대하여 동적 시험을 수행하였다. 이들 방진체결장치에 작용하는 하중을 평가하기 위하여 동적 강성을 변화하면서 차량-궤도 상호작용해석을 수행하였다. 해석의 중요 입력요소인 궤도틀림은 측정자료를 토대로 도출된 궤도틀림 PSD(Power Spectral Density) 회귀 함수로 고려하였다. 도시철도의 다양한 운영환경을 고려하여 방진체결장치에 작용하는 하중을 평가한 후, 평가된 하중을 토대로 방진체결장치의 성능시험하중에 대한 기준을 제시하였다.

• 국제강구조저널
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• 제18권5호
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• pp.1617-1630
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• 2018

The crucial differences between conventional rail with split-type connectors and continuous welded rails are axial stress in the longitudinal direction and stability, as well as other issues generated under the influence of loading effects. Longitudinal stresses generated in continuously welded rails on railway bridges are strongly influenced by the nonlinear behavior of the supporting system comprising sleepers and ballasts. Thus, the track structure interaction cannot be neglected. The rail-support system mentioned above has properties of non-uniform material distribution and uncertainty of construction quality. The linear elastic hypothesis therefore cannot correctly evaluate the stress distribution within the rails. The aim of this study is to apply the nonlinear finite element method using the nonlinear coupling interface between the track and structural model and to illustrate the welded rail behavior under the loading effect and uncertain factors of the ballast. Numerical results of nonlinear finite analysis with a three-dimensional solid and frame element model are presented for a typical track-bridge system. A composite plate girder, modeled by solid and shell elements, is also analyzed to consider the behavior of the welded rail. The analysis result showed buckling under the independent calculations of load cases, including 'temperature change', 'bending of the supporting structure', and 'braking' of the railway vehicle. A parametric study of the load combination method and the loading sequence is also included in this analysis.

• 한국운동역학회지
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• 제13권3호
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• pp.199-215
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• 2003

The purpose of this study was to attempt new starting motion and supply present starting motion in the 500M short track speed skating according to the center of gravity position. The center of gravity position ratio was divided starting motion into five(type A : front 80%-back 20%, type B front 70%-back 30%, type C : front 50%-back 50%, type D : front 30%-back 70%, type E : front 20%-back 80%). The three dimension motion analysis with DLT(direct linear transformation) method was executed using two video cameras. The following conclusion was that It was appear that reaction and execution time in starting motion was the most short in type B. It was characteristic that step of skaters was shorten and center of gravity position ratio was not effect to change of the step in each event. It was appear that the displacement of type D and type E were longer than that type A and type B during the starting motion. It was appear that skill types of center of gravity position ratio to the front were lower than that to the back and contract a posture. Observing the above, it was conclusion that skill type B of center of gravity position ratio to the tent was more effect than that to the back. But it is important that these skill type was most used to the competition and estimate the result.

• 대기
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• 제19권2호
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• pp.183-198
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• 2009

The purpose of this study is to summarize the tropical cyclone (TC) activity of 2008 over the western North Pacific including the verification of the official track and intensity forecast errors of these TCs. The TC activity - frequency, Normalized Typhoon Activity (NTA), and life span - was lower than 58-year (1951-2008) average. 22 tropical cyclones of tropical storm (TS) intensity or higher formed in the western North Pacific and the South China Sea in 2008. The total number is less than 58-year average frequency of 26.4. Out of 22 tropical cyclones, 11 TCs reached typhoon (TY) intensity, while the rest 11 TCs only reached severe tropical storm (STS) and tropical storm (TS) intensity - six STS and five TS storms. One typhoon KALMAEGI (0807) among them affected the Korea peninsula. However, no significant impact - casualty or property damage - was reported. On average of 22 TCs in 2008, the Korea Meteorological Administration (KMA) official track forecast error for 48 hours was 229 km. There was a big challenge for individual cyclones such as 0806 FENGSHEN and 0817 HIGOS presenting significant forecast error, with both intricate tracks and irregular moving speed. The tropical cyclone season in 2008 began in April with the formation of NEOGURI (0801). In May, four TCs formed in the western North Pacific in response to enhanced convective activity. On the other hand, the TC activity was very weak from June to August. It is found that the unusual anti-cyclonic circulation in the lower level and weak convection near the Philippines are dominant during summertime. The convection and atmospheric circulation in the western North Pacific contributed unfavorable condition for TC activity in the 2008 summertime. The 2008 TC activity has continued the below normal state since mid 1990s which is apparent the decadal variability in TC activity.

• 한국철도학회논문집
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• 제18권6호
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• pp.543-551
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• 2015

급속경화궤도는 자갈궤도를 콘크리트궤도로 개량하는 공법으로서 야간 차단시간에 공사가 이루어지기 때문에 시공속도를 충분히 확보하는 것이 중요하다. 시공시간의 대부분은 자갈을 철거하고 재포설하는 과정에 소요되는데 도상자갈을 교체하지 않는 무교환방식이 적용 가능하다면, 시공시간 및 공사비를 대폭적으로 절감할 수 있다. 본 논문에서는 도상자갈 무교환방식의 급속경화궤도공법을 개발하기 위하여 침투성이 매우 높은 대체 충전재를 제시하고 재료의 공극조건을 고려하여 층별로 분리주입하는 시공방식을 도입하였다. 분리주입은 공극률이 높은 상부도상층과 공극률이 낮은 하부 혼입층에 최적화된 재료를 분리 주입하여 필요한 소요강도를 확보할 수 있다. 이를 달성하기 위하여 우선적으로 도상자갈의 크기, 분포도, 형상에 따른 공극률, 공극의 크기, 유효길이, 비틀림도, 침투성에 따른 충전재의 유동학적 해석을 통하여 최적의 충전재를 설계하고자 하였다. 하부 혼입층에 충전되는 1차 충전재료는 세립화 도상의 충전성과 부착력을 확보할 수 있는 폴리머계 재료를 도입하였으며, 상부 도상층에 충전되는 2차 충전재는 상온 반응성 마그네시아-포스페이트(MPC, Magnesium-Phosphate Ceramic)를 도입하였다. 선정재료 및 구조에 대한 역학시험 결과, 기존 급속경화궤도에 준하는 성능을 확인하였다.