• 대한기계학회논문집A
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• 제33권11호
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• pp.1353-1356
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• 2009

As a method obtaining linear thrust force for the magnet wheel producing a strong traction torque, the concept of magnetic shield is suggested and compared with the existing approaches. Specially, as the magnet wheel, in which the permanent magnets rotate mechanically instead of ac driving to make traveling field, is physically similar with the rotary induction motor, there is a periodical force ripple in tangential direction as well as normal direction. But, the force ripple can be suppressed from a shape change of the shield plate. Namely, the change brings out a change of entry and exit effect of the circumferential field for the magnet wheel. The feasibility of the shield concept is verified from simulation and experiment.

• 대한기계학회논문집
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• 제11권1호
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• pp.63-73
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• 1987

본 논문에서는 차륜을 등방성, 균질 재료라고 가정하였으며 웨브와 림의 두께 가 서로 다른 환형원판으로써 내원주는 고정되고 외원주는 자유라고 가정하였다. 외 원주상의 한 점에서 철로와의 구름조건에 따라 변하는 반경방향의 반력에 의한 내평면 압축응력과 원판의 회전에 의한 내평면 압축응력을 고려하고, 두께가 변하는 웨브와 림의 경계면에서의 연속조건을 이용하여 차륜의 횡진동방정식을 세워서 Rayleigh-Ritz 방법으로 수치해석을 하여 고유진동수와 임계좌굴하중을 계산하고, 실제 차륜의 1/6크 기로 형상화하여 제작한 연성진동장치로 실험하여 이론치와 비교, 검토하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.695-698
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• 2004

STSAT RWA (Reaction Wheel Assembly) micro-vibration is measured using KISTLER dynamic plate that can provide the time signals of three orthogonal forces and torques simultaneously up to 400Hz. In the post-processing, measured data are evaluated with respect to the wheel spin rate in both time and frequency domains, and the static/dynamic unbalances are evaluated from the extracted first harmonic component. Also the friction torque profile at each wheel speed is estimated from the measured data. Several higher order harmonic components are observed, that comes from its rotor shape as well as the wheel bearing characteristics. One of the most peculiar characteristics of this wheel is that the dynamic properties of two radial unbalance components are much different from each other as the RWA mounting configuration on a spacecraft is different from conventional RWA mounting configuration. Rocking mode is not appeared below 400Hz for all operating speed because the wheel size is very small. The post-processed results will be used for jitter analysis of STSAT due to RWA micro-vibration.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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• pp.1080-1085
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• 2002

A dynamic characteristics of existing steel plate girder railway bridges without ballast were investigated from the finite element analysis. Span lengths, types of vehicle and running speeds are selected as parameters for analyses. For more exact analysis, it was adopted that 3-dimensional bridge models and wheel loads were produced by averaging field measured wheel loads of running vehicles at various speeds. Dynamic vertical deflections, dynamic amplification factors and vertical accelerations of bridges having 9m, 12m and 18m span length were investigated and compared with the limit values specified in Korean railway bridge specification.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권2호
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• pp.143-149
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• 2017

Purpose: In recent years, weight reduction for improving fuel efficiency of the vehicle and cost reduction have been developed. The structure of suspension link is widely used as a single plate press structure which can reduce process and weight compared to existing pipe welding method. However, it was found that the lifetime of a single plate press structure is determined by initial defects that occurred during initial manufacturing rather than fatigue damage caused by driving. Methods: I research the mechanism of failure phenomenon of the single plate press assist arm of rear wheel. In addition, I investigate durability effect parameters to determine the link lifetime in inserting bush into single plate press process through durability test. Conclusion: I discover significant durability effect parameter in inserting bush into single plate press process. It is expected that the durability can be improved by suggesting a bush inserting process inspection guide for similar suspension link like single plate press structure.

• Journal of Biosystems Engineering
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• 제9권2호
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• pp.8-18
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• 1984

To investigate the most important factors affecting the mobility of power tiller and to find the method which can be used for predicting the mobility of power tiller in soft paddy field, a series of field experiment was performed with two models of power tiller (8ps and 6ps diesel). From the results obtained throughout field experiment, the following conclusions were derived. 1. The wheel sinkage of power tiller during both traveling and field operations, which mainly influence the mobility, could be predicted from both plate ($50{\times}100mm$) sinkage and soil cone index (30-degree cone with 2 and $6cm^2$ base area). 2. Prediction of wheel sinkage from the rectangular plate sinkage was found to be more suitable compared with the cone index. 3. The upper limit of rectangular plate sinkage was found as 15 centimeter for operation of power tiller in muddy field which is equivalent of $1kg/cm^2$ of $2cm^2$ cone index value.

• Steel and Composite Structures
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• 제18권2호
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• pp.357-374
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• 2015

Orthotropic decks composed of deck plate, ribs, cross beams and wearing surface are frequently used in industry to span long distances due to their light structures and load carrying capacities. As a result they are broadly preferred in industry and there are a lot of bridges of this type exist in the world. Nevertheless, some of them cannot sustain the anticipated service life and damages in form of cracks develop in steel components and wearing surface. Main reason to these damages is seen as the repetitive wheel loads, namely the fatigue loading. Solutions to this problem could be divided into two categories: qualitative and quantitative. Qualitative solutions may be new design methodologies or innovative materials, whereas quantitative solution should be arranging dimensions of deck structure in order to resist wheel loads till the end of service life. Wearing surface on deck plate plays a very important role to avoid or mitigate these damages, since it disperses the load coming on deck structure and increases the bending stiffness of deck plate by forming a composite structure together with it. In this study the effect of Elastic moduli, Poisson ratio and thickness of wearing surface on the stresses emerged in steel deck and wearing surface itself is investigated using a FE-model developed to analyze orthotropic steel bridges.

• 항공우주기술
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• 제3권2호
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• pp.25-33
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• 2004

본 논문에서는 인공위성 반작용휠의 미소진동 측정을 위한 테스트 장비와 이를 이용하여 실측한 반작용휠의 미소진동을 측정 및 분석 결과를 소개한다. 위성의 미소진동은 KISTLER dynamic platform 이라는 400Hz 이내의 3축의 힘과 3축의 토크를 동시에 측정할 수 있는 장비에 의해 측정되며 측정된 데이터는 회전 속도에 따라 3차원 주파수 분석, order tracking 등의 방법을 이용하여 분석된다. 반작용휠의 미소진동 분석 결과, 회전 속도와 비례하는 일차 성분 외에 고차 조화 성분, 구조 진동 성분, 회전 속도에 따라 고유진동수가 변하는 rocking 모드 성분 등을 관찰할 수 있었으며, 휠의 정적 및 동적 불균형은 각각 0.79gcm과 17.4gcm²으로 나타났다. 이러한 다양한 진동 성분들은 회전체의 특성, 구조물의 특성 및 베어링의 영향으로 기인한다.

• 한국CDE학회논문집
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• 제20권3호
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• pp.230-237
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• 2015

Soil deformation on the off-load ground is significantly affected by soil conditions, such as soil type, water content, and etc. Thus, the soil characteristics should be estimated for predicting vehicle movements on the off-load conditions. The plate-sinkage test, a widely-used experimental test for predicting the wheel-soil interaction, provides the soil characteristic parameters from the relationship between soil stress and plate sinkage. In this study, soil stress under the plate-sinkage situation is calculated by the DEM (Discrete Element Method) model. We developed a virtual soil bin with DEM to obtain the vertical reaction forces under the plate pressing the soil surface. Also parametric studies to investigate effects of DEM model parameters, such as, particle density, Young's modulus, dynamic friction, rolling friction, and adhesion, on the characteristic soil parameters were performed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1344-1368
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• 2007

선진국인 일본과 미국, 유럽 등에서는 철도운영기관에서 경영합리화 방안으로 철도차량 검수인원 최소화를 위한 판타그라프 습판마모 및 차륜마모 상태 자동측정 시스템(예를 들면, CCD 카메라에 의한 자동 측정 등)을 '80년대 후반부터 도입하고 있는 실정이다. 국내에서는 '90년대 후반부터 도시철도 운영기관에서 경영합리화 방안의 일환으로 판타그라프 습판 및 차륜 마모 자동측정 시스템 적용에 대해 관심을 갖기 시작하였다. 이후 2002년도부터 한국철도공사의 신설 차량기지에 설치하기 시작하였다. 기 적용된 외국 및 국내의 CCD 카메라에 의한 판타그라프 습판마모상태 자동측정 시스템을 분석하여 IT 강국으로써의 새로운 첨단기술 방식을 적용한 CCD 카메라에 의한 판타그라프 습판마모 측정방법 및 관리방안이나 국내실정에 맞지 않는 검사관리 항목 등을 개선 적용한 사례(국내 운영기관)들을 연구, 국내 도시철도 운영기관에 적용토록 함으로써 경영합리화 실현 및 국내의 IT 선진기술을 해외철도 운영기관에 적용할 수 있는 단초를 제공하고자 한다.