• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1685-1690
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• 2010

This paper describes the calculation and application of the speed profile for the train speed control when the train is operated by ATO(Automatic Train Operation). We propose a speed profile calculation method considering the speed limitation and the jerk limitation, in order to maintain the quality of the train automatic operation. In previous works, ATO calculates a desired speed profile along the time, and controls the train to follow the profile. In this case, it may be hard to follow the restrictive speed along the location or to stop the train with a low location error, because of the difference between the desired location at each time and the real location of the train due to the control error. In the proposed method in this paper, we calculate a desired speed profile along the time considering the speed and jerk limitation first, and derive a speed profile along the location using it. If the restrictive speed profile is changed or the train speed strayed from the speed profile, ATO system calculates new speed profile and applies it immediately. Because ATO system controls the train speed based on the train location, the accuracy of the train location control can be improved. A simulation system for the test of the automatic train operation using this method is designed.

• 한국항공운항학회지
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• 제21권2호
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• pp.26-32
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• 2013

The rotorcraft makes lift and control forces by the rotor thrust. At the development phase of the rotorcraft, the operational limitations have to be established. And it shall be demonstrated to operate the rotorcraft safely within the limitations. This paper introduces establishment and evaluation results of operational rotor speed limitations for the medium class utility rotorcraft. And it shows the follow-up activities after design changes of rotor speed indicators and aural warning systems for implementing the rotor speed limitations.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.591-596
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• 2000

Flow through compliant tubes with linear taper in wall thickness is numerically simulated by finite element analysis. Two models are examined: a planar two-dimensional channel, and an axisymmetric tube. For verification of the numerical method, flow through a compliant stenotic vessel is simulated and compared to existing experimental data. Computational results for an axisymmetric tube show that as cross-sectional area falls with a reduction in downstream pressure, flow rate increases and reaches a maximum when the speed index (mean velocity divided by wave speed) is near unity at the point of minimum cross-section area, indicative of wave speed flow limitation or "choking" (flow speed equals wave speed) in previous one-dimensional studies. For further reductions in downstream pressure, flow rate decreases. Cross-sectional narrowing is significant but localized. When the ratio of downstream-to-upstream wall thickness is ${\le}$ 2 the area throat is located near the downstream end; as wall taper is increased to ${\ge}$ 3 the constriction moves to the upstream end of the tube. In the planar two-dimensional channel, area reduction and flow limitation are also observed when outlet pressure is decreased. In contrast to the axisymmetric case, however, the elastic wall in the two-dimensional channel forms a smooth concave surface with the area throat located near the mid-point of the elastic wall. Though flow rate reaches a maximum and then falls, the flow does not appear to be choked.

• 대한조선학회논문집
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• 제51권5호
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• pp.349-355
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• 2014

The resistance test of a high speed craft such as planing ship is performed with a high speed towing carriage instead of ordinary towing carriage because of the speed limitation. In the resistance test using high speed towing carriage, the model ship is fixed to the carriage to restrain the running attitude for enough measuring time. Such method is called fixed model test method. In the fixed model test method, to get the appropriate running attitude, the model test is iteratively repeated until the trim moment and lift force are close to zero. In this research, trim free model test method is investigated to reduce the number of iteration. And, the limitation of towing speed range in the trim free model test method is investigated.

• 디지털콘텐츠학회 논문지
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• 제15권3호
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• pp.425-432
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• 2014

4K 초고속 카메라 촬영은 해상도 및 셔터스피드 증가로 인해 빠른 피사체의 영상을 모션 블러 없이 Full HD 4배 해상도로 촬영이 가능하다. 그러나 해당 촬영은 데이터 량의 증가와 광량, 포커스 등 여러가지 제약사항이 뒤따른다. 증가된 셔터스피드로 인해 광량 부족 현상을 가져올 수 있어 조리개를 개방하여 촬영하는 경우가 많아 초점 조절에 제약이 따른다. 또한 증가된 해상도와 프레임레이트로 인해 저장 공간의 한계가 뒤따르기 때문에 촬영 기록에 제한이 따르고 있다. 따라서 본 연구는 4K 초고속 카메라(Phantom Flex 4K) 제작 사례를 통해 위와 같은 한계점들에 대해 분석하고, 이를 극복하기 위한 효율적인 워크플로우를 디자인 하였다.

• 한국소음진동공학회논문집
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• 제22권5호
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• pp.413-421
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• 2012

In industry, various rotating machinery such as pumps, gas turbines, compressors, electric motors, generators are being used as an important facility. Due to the industrial development, they make high performance(high-speed, high-pressure). As a result, we need more intelligent and reliable machine condition diagnosis techniques. Diagnosis technique using hidden Markov-model is proposed for an accurate and predictable condition diagnosis of various rotating machines and also has overcame the speed limitation of time/frequency method by using compensation of the rotational speed of rotor. In addition, existing artificial intelligence method needs defect state data for fault detection. hidden Markov model can overcome this limitation by using normal state data alone to detect fault of rotational machinery. Vibration analysis of step-up gearbox for wind turbine was applied to the study to ensure the robustness of diagnostic performance about compensation of the rotational speed. To assure the performance of normal state alone method, hidden Markov model was applied to experimental torque measuring gearbox in this study.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1533-1536
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• 2003

Dynamic model of the rubber-tired AGT light rail vehicle. various load and boundary conditions between vehicle and infrastructures(running track. guidance rail) were defined to analyze vehicular dynamic behaviors occurred by inclement weather(strong wind and earthquake). The dynamic analysis were performed by using a commercialized software RecurDyn. whose results for the magnitudes of wind and earthquake showed the resultant forces and accelerations between car body and bogie, or bogie guidance frame and infrastructures in the various track conditions(straight or curved tracks) and train velocities. Based on these results, speed limitation of tile vehicle were proposed to ensure system stability and passengers safety.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1370-1378
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• 2007

고속철도 교량은 고속주행 열차의 차축 주기하중 효과와 교량 고유의 동적특성에 의한 동적 증폭 효과로 인하여 구조물의 안전성에 영향을 받는다. 그리고 교량의 과도한 변형으로 인하여 차륜과 레일의 접촉력 감소, 궤도틀림 등의 윤중 변동이 일어나 열차의 주행안전성 및 승차감을 저해할 수 있다. 이러한 궤도 안전성을 확보하기 위하여 동적거동에 대한 교량상판수준의 수직가속도 제한, 차륜-레일간의 접촉과 열차주행 안전성 확보를 위한 상판 면틀림 제한, 단부 회전각 변위 제한, 차량하중에 의한 교량의 수직 처짐 제한을 반드시 만족시켜야 하며, 필수적으로 공진에 대한 검토도 이루어져야 한다. 신설되는 호남고속철도에서는 기존의 경부고속철도와 다른 콘크리트 도상을 적용하고, 궤도간격, 설계열차하중 등이 변경되어 적용되므로 새로운 동적안정성 요구조건을 적용하게 된다. 본 연구에서는 콘크리트교량에 비해 진동특성이 취약한 것으로 알려진 강합성 거더 고속철도 교량의 동적거동 분석을 수행하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.695-698
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• 2010

본 논문은 High-speed signal에 대한 기본적인 설계 방법론, Differential signaling, Impedence matching, Decoupling Method 등에 대하여 논한 후 High-speed signal 의 전송 품질을 개선하기 위한 GND via 의 효과에 대하여 논하고자 한다. S-parameter simulation 및 실제 제품 적용 후 파형의 변화를 관찰하여 GND via 의 효용성을 살펴보아 High-speed signal Design 할 때 Design limitation 상황에 대해 적절한 방법론을 말하고자 한다.

• 대한조선학회논문집
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• 제50권6호
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• pp.407-413
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• 2013

In the conventional towing tank, the ordinary towing carriage has a speed barrier which caused not only by the limitation of the length of towing tank but also the limitation of acceleration. Therefore the length of the towing tank should be decided carefully from the planning stage of the towing tank construction. Consequently the acceleration of the towing carriage should be taken less than 0.06g practically to avoid the slip of the wheel on rail. Due to the increasing demand of the high speed experiments on the development of special novel ship, the requirement of the high speed towing carriage is continuously increased recently. When the minimum measuring time of the towing experiment is prescribed as five seconds, the carriage should be accelerated with higher than 0.12 g to get the speed of 18 m/sec even in the towing tank having a length of 400m in length approximately. This means that the requirement of acceleration is bigger than twice of the ordinary practices of carriage acceleration. In such a condition the exerted total power of motor could not converted to traction force for the acceleration of the carriage without slip. To over come these difficulties a pair of horizontal traction wheels are reinforced to each of the ordinary vertical carrier wheel and appropriate suspension system has been devised for the towing tank of super high speed operation. It is believed that the design of novel suspension system adaptable for the high speed acceleration of towing carriage will play a important role as a reference for the remodeling of the towing tank for high speed experiment.