• 한국유체기계학회 논문집
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• 제15권1호
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• pp.13-20
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• 2012

A vertical-axis multistage pump with low specific speed was developed, satisfying performance requirements such as flow rate, total head, and NPSH. The developed pump was designed through conceptual design, configuration design, and performance analysis by CFD which were established in KIMM. The prototype pump's mechanical wholesomeness besides hydraulic performances were verified by running test, performance test, and reliability test.

• 동력기계공학회지
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• 제14권1호
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• pp.53-58
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• 2010

A three-dimensional source distribution method is presented for the prediction of motions and vertical bending moments of ships travelling with forward speed in regular waves. Comparisons between theoretical and experimental results are shown for the motion responses and vertical bending moment of the S175 container ship model by Watanabe et al. The model ship was made of synthetic resins so as to simulate bending rigidity of a full scale ship. Numerical results are compared with experimental and numerical ones obtained in the literature. The results of comparison confirmed the validity of the proposed approach.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.458-463
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• 2012

This case study refers to resonance with vertical pumps. Vibration problem occurring after the inverter was installed for speed control. Its problem was appeared any revolution under rated speed. Vibration data was acquired during normal operation and transient state. We examined FRF on its resonance in field and also analyzed a result by finite element method. There was carried out the retrofit in field which was based on these results for solving problem.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.360-367
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• 2003

This paper presents passive vibration control method to suppress train-induced vibration on a long-span steel arch bridge. According to the train load frequency analysis, undesirable resonance of a bridge will occur when the impact frequency of the train axles are close to the modal frequencies of the bridge. Because the first mode shape of the long-span steel arch bridge may take anti-symmetric shape along the bridge direction, however, the optimal control configuration for resonance suppression should be considered carefully In this study, bridge-vehicle element is used to estimate the bridge-train interaction precisely. From the numerical simulation of a loom steel arch bridge under TGV-K train loading, dynamic magnification influences are evaluated according to vehicle moving speed and efficient control system with passive dampers are presented in order to diminish the vertical displacement and vertical acceleration.

• 한국정밀공학회지
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• 제13권7호
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• pp.158-166
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• 1996

In this study, a flexible disk grinding process is applied in order to produce high precision product. A new model was developed considering feed motion along horizontal and vertical direction. Different types of feed speed variation was tested with respect to distinct process stages in order to achieve flat surface. It was observed that highest order polynomial form for both horizontal and vertical feed speed variation among the proposed categories produced surface close to flat one. Disk deflection trend during the process was visualized confirming the proposed scheme. Cutting force and VRR(volume removal rate) was observed as an aid to process planning.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1676-1682
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• 2008

The vertical curve of railway is installed in changing point where the gradient is more than a certain degree to ensure safe operation of train and comfort of passengers. As a result of CAD work with 3D coordination by using the existing equation, it was found that the simple equation about vertical curve installation suggested in the surveying engineering or railway regulations did not reflect theoretical curvature of circular curve in a case of steep grade and large vertical radius. In this study, for derive precision equation and transition curve about vertical curve, gradient parameters, equation of circles and transition curve equation were used, and it was verified by CAD that the derived equation is exactly satisfied with parameters of geometrical circular and transition curve. This equation could be used to provide more smoothing operation of train and comfort of passengers on vertical curves, especially in case that railway requires precision vertical alignment of track such as super high-speed railway, LRT or Maglev system.

• 한국소음진동공학회논문집
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• 제19권1호
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• pp.35-41
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• 2009

Through the multibody dynamic simulation, the analysis model of the modalohr freight car of the DMT freight car was developed. By using the developed analysis model, the running dynamic characteristics was inquired through the dynamic analysis about the modalohr freight car. As the running speed and the primary suspension were increased, the lateral and vertical vibration accelerations of the car-body and the bogie were also increased. In case of the lateral vibration acceleration of the car-body, however, review should be considered since it can be influenced by the nonlinear characteristic of the primary suspension. The lateral and vertical vibration of the car-body were generated at the frequency of $2{\sim}3\;Hz$ and $7{\sim}8\;Hz$. And the lateral and vertical vibration of the bogie were generated at the frequency of $25{\sim}35\;Hz$ at the low speed section, $40{\sim}50\;Hz$ at the high speed section.

• 한국통신학회논문지
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• 제33권5A호
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• pp.536-541
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• 2008

우리에게 다가온 4G 차세대 이동통신 시스템은 유 무선 네트워크의 통합과 더불어 이동성의 증가와 고속 데이터 전송(음성 및 멀티미디어 데이터)을 제공하는 형태로 진화해 나갈 것이다. 여기에서 이동성 지원의 가장 핵심이 될 수 있는 것은 바로 이동하고 있는 단말의 경로 예측이며, 실제로 무선망이 처음 소개되면서 이에 대한 연구가 활발히 있었으나 실제 이동 환경에 적용하기에는 위험부담이 크기 때문에 적용하기가 쉽지 않았다. 본 논문에서는 이러한 문제를 고려하여 기존의 이동성 예측 알고리즘을 기반으로 Signaling Power Level 비교 및 Speed 기반의 예측 기법을 도입하여 실제 환경에 최적화 되어진 예측 알고리즘을 제안하였다. 그리고 기존 예측 알고리즘과 제안하고 있는 예측 알고리즘을 OPNet 시뮬레이션을 통해 비교하여 보았다.

• Steel and Composite Structures
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• 제33권2호
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• pp.209-224
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• 2019

This paper describes a study of the mapping relationship between the vertical deformation of bridge structures and rail deformation of high-speed railway, taking the interlayer interactions of the bridge subgrade CRTS II ballastless slab track system (HSRBST) into account. The differential equations and natural boundary conditions of the mapping relationship between the vertical deformation of bridge structures and rail deformation were deduced according to the principle of stationary potential energy. Then an analytical model for such relationship was proposed. Both the analytical method proposed in this paper and the finite element numerical method were used to calculate the rail deformations under three typical deformations of bridge structures and the evolution of rail geometry under these circumstances was analyzed. It was shown that numerical and analytical calculation results are well agreed with each other, demonstrating the effectiveness of the analytical model proposed in this paper. The mapping coefficient between bridge structure deformation and rail deformation showed a nonlinear increase with increasing amplitude of the bridge structure deformation. The rail deformation showed an obvious "following feature"; with the increase of bridge span and fastener stiffness, the curve of rail deformation became gentler, the track irregularity wavelength became longer, and the performance of the rail at following the bridge structure deformation was stronger.

• 한국철도학회논문집
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• 제18권1호
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• pp.33-42
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• 2015

궤도 안전을 위한 핵심 용품인 레일체결장치의 구성품 중 레일패드 또는 베이스플레이트 패드의 정적 수직강성은 궤도 전체의 강성 결정 시 중요 인자이며, 패드 제품의 제조과정에서 품질관리 기준이 된다. 패드의 정적 수직강성 확인은 시험을 통해 가능하며, 시험방법으로는 철도분야에 널리 사용되고 있는 EN 13146-9 및 이를 부합화한 KRS TR 0014 규격이 있다. 본 논문에서는 상기 규격의 정적 수직강성 시험방법 중 예비하중 단계, 하중 제거 수준 및 하중 유지시간 관련 문제점 개선을 위해, 패드 관련 국내외 시험규격을 분석한 후 시험방법 안을 제시하였고, 철도현장에 사용되고 있는 패드 4종을 이용하여 시험방법 안을 적용한 정적 수직강성 시험을 수행하였다. 또한 시험방법 안의 적합성을 판단하기 위하여 시험결과에 대한 유효성 평가를 수행하였다.