• 드라이브 ㆍ 컨트롤
• /
• 제17권1호
• /
• pp.1-12
• /
• 2020

This study was to develop a simulation model of a compound planetary gear reducer for the final driving shaft using a gear analysis software (KISSsoft, Version 2017, KISSsoft AG, Switzerland). The aim of this study is to analyze transmission error and the tooth load distribution through micro-geometry using the simulation model. The tip and root relief were modified with Micro-geometry in the profile direction, and crowning was modified with Micro-geometry in the lead direction. The transmission error was analyzed using the PPTE (Peak to Peak Transmission Error) value, and the tooth load distribution was analyzed for the concentrated stress on the tooth surface. As a result of modifying tip and relief in the profile direction, the transmission error was reduced up to 40.7%. In the case of modifying crowning in the lead direction, the tooth load was more evenly distributed than before and decreased the stress on the tooth surface. After modifying the profile direction for the 1st and 2nd planetary gear train, the bending and contact safety factors were increased by 31.7% and 17%, and 18.3% and 12.5% respectively. Moreover, the bending and safety factors after modifying lead direction were increased by 59.5% and 32.7%, respectively for the 1st planetary gear train, and 59.6% and 43.6%, respectively for the 2nd planetary gear train. In future studies, the optimal design of a compound planetary gear reducer for the final driving shaft is needed considering both the transmission error and tooth load distribution.

• 한국철도학회논문집
• /
• 제18권3호
• /
• pp.175-185
• /
• 2015

일반적으로 열차분야에서 분기기 시스템은 안전성과 직접적으로 연관되기 때문에 높은 신뢰성이 요구된다. 특히 자기부상열차의 분기기 시스템은 대차가 궤도를 감싸는 구조적 특징으로, 고가궤도 전체가 움직여야 한다. 이러한 이유로 자기부상열차의 분기기는 강 재질로 설계되었다. 강 거더의 분기기는 콘크리트 거더에 비하여 진동측면뿐만 아니라 거더의 처짐에도 취약하다. 그러므로 자기부상열차가 유연한 분기기 위를 통과 할 때, 부상안정성 예측이 매우 중요하다. 본 논문의 목표는 자기부상열차와 분기기 거더의 연성된 동역학 해석모델을 개발하고, 공진예측 및 차량의 부상안정성 예측에 있다. 이를 위해서 차량의 3차원 다물체 동역학 모델을 개발 하였고, 분기기 거더와 모달중첩법을 이용한 연성모델링을 수행하였다. 개발된 해석모델은 실측 실험과 비교를 통해서 해석모델의 타당성을 검증하였다.

• Structural Monitoring and Maintenance
• /
• 제4권2호
• /
• pp.115-131
• /
• 2017

Classical flutter of wind turbine blades indicates a type of aeroelastic instability with fully attached boundary layer where a torsional blade mode couples to a flapwise bending mode, resulting in a mutual rapid growth of the amplitudes. In this paper the monitoring problem of onset of flutter is investigated from a detection point of view. The criterion is stated in terms of the exceeding of a defined envelope process of a specific maximum torsional vibration threshold. At a certain instant of time, a limited part of the previously measured torsional vibration signal at the tip of blade is decomposed through the Empirical Mode Decomposition (EMD) method, and the 1st Intrinsic Mode Function (IMF) is assumed to represent the response in the flutter mode. Next, an envelope time series of the indicated modal response is obtained in terms of a Hilbert transform. Finally, a flutter onset criterion is proposed, based on the indicated envelope process. The proposed online flutter monitoring method provided a practical and direct way to detect onset of flutter during operation. The algorithm has been illustrated by a 907-DOFs aeroelastic model for wind turbines, where the tower and the drive train is modelled by 7 DOFs, and each blade by means of 50 3-D Bernoulli-Euler beam elements.

• 한국자동차공학회논문집
• /
• 제20권2호
• /
• pp.47-55
• /
• 2012

This work deals with dynamic analysis of a monorail system with magnetic caterpillar where magnets are embedded inside each articulated element of the caterpillar, augmenting traction force of main rubber wheels to climb up slope up to 15 degree grade. Considerations are first given to determine stiffness of the primary and secondary suspension springs in order for the natural frequencies of car body and bogie associated with vertical, pitch, roll and yaw motion to be within generally accepted range of 1-2 Hz. Equations for calculating magnetic force needed to climb up given slope are derived, and a magnetic caterpillar system for 1/6 scale monorail is designed based on the derivation. To assess the hill climbing ability and cornering stability, and make sure smooth operation of the side and vertical guiding wheels which is critical for safety, a multibody model that takes into account of every component level design characteristics of car, bogie, and caterpillar is set up. Through hill climbing simulation and comparison with measurement of the limit slope, the validity of the analysis and design of the magnetic caterpillar system are demonstrated. Also by studying the curving behavior, maximum curving speed without rollover, functioning of lateral motion constraint system, the effects of geometry of guiding rails are studied.

• 조명전기설비학회논문지
• /
• 제18권2호
• /
• pp.142-149
• /
• 2004

본 논문은 바람으로부터 최대출력을 추출하기 위해 계통연계 풍력발전시스템의 신경회로망 제어기와 추출된 최대출력을 계통에 전달하기 위한 전력제어기를 제안한다. 유도발전기, 변압기, 정류기 및 인버터 등으로 구성된 제어기를 갖춘 풍력발전시스템의 모델링과 시뮬레이션에 대해 검토하고자 한다. 본 논문에서는 동특성해석을 위해 드라이브 트레인 모델, 유도발전기 모델과 계통접속 모델을 제시한다. 신경회로망 제어기는 풍차날개의 피치각을 제어하여 바람으로부터 최대출력을 추출한다. 피치제어방법은 기계적으로 복잡하지만 제어성능은 스톨제어보다 우수하게 된다. MATLAB으로 수행한 시뮬레이션 결과는 발전기 토오크, 발전기 회전속도, 피치각, 계통으로 주입되는 유효/무효전력 등을 예시하고 있으며 그 결과를 보면 제안된 제어기의 효용성을 입증할 수 있다.

• 대한기계학회논문집A
• /
• 제35권1호
• /
• pp.11-15
• /
• 2011

본 논문은 풍력터빈의 출력 제어 방법에 관한 논문이다. MW급 풍력 터빈 출력제어의 기본 제어 구조는 가변속도 가변피치 방식을 사용한다. 가변속도 가변피치 제어는 파워 커브를 추종하기 위한 방법으로서, 풍속변화에 따라 이 제어방식이 어떻게 적용되는지 논의한다. 제어 시스템 설계를 위하여 단순화된 드라이브 트레인 모델이 사용되었다. 제어 시스템은 토크제어와 피치제어로 구성되고, 제시된 동적 모델을 사용하여 설계된 제어 시스템의 시뮬레이션 결과에 대하여 논의한다.

• 한국자동차공학회논문집
• /
• 제12권4호
• /
• pp.119-128
• /
• 2004

With the growing traffic density and increasing comfort requirements, the automation of the drive train will gain importance in vehicles. The automatic clutch actuation relieves the drivers especially in urban driving and stop-and-go traffic conditions. This paper describes the dynamic modeling of a clutch actuator and clutch spring. The dynamic model of the clutch system is developed using MATLAB/Simulink, and evaluated by experimental data using a test rig. This performance simulator is useful to develop the clutch-by-wire (CBW) system for an automated manual transmission (AMT). The electro-mechanical type CBW system is also implemented as an automatic clutch for AMT. The prototype of CBW system is designed and implemented systematically, which is composed of an electric motor, worm gear and slider-crank mechanism. The test rig is developed to perform the basic function test of the automatic clutch, and the developed prototype is validated by the experimental data on the test rig.

• Smart Structures and Systems
• /
• 제29권1호
• /
• pp.251-266
• /
• 2022

Structural Health Monitoring (SHM) of critical infrastructure comprises a major pillar of maintenance management, shielding public safety and economic sustainability. Although SHM is usually associated with data-driven metrics and thresholds, expert judgement is essential, especially in cases where erroneous predictions can bear casualties or substantial economic loss. Considering that visual inspections are time consuming and potentially subjective, artificial-intelligence tools may be leveraged in order to minimize the inspection effort and provide objective outcomes. In this context, timely detection of sensor malfunctioning is crucial in preventing inaccurate assessment and false alarms. The present work introduces a sensor-fault detection and interpretation framework, based on the well-established support-vector machine scheme for anomaly detection, combined with a coalitional game-theory approach. The proposed framework is implemented in two datasets, provided along the 1st International Project Competition for Structural Health Monitoring (IPC-SHM 2020), comprising acceleration and cable-load measurements from two real cable-stayed bridges. The results demonstrate good predictive performance and highlight the potential for seamless adaption of the algorithm to intrinsically different data domains. For the first time, the term "decision trajectories", originating from the field of cognitive sciences, is introduced and applied in the context of SHM. This provides an intuitive and comprehensive illustration of the impact of individual features, along with an elaboration on feature dependencies that drive individual model predictions. Overall, the proposed framework provides an easy-to-train, application-agnostic and interpretable anomaly detector, which can be integrated into the preprocessing part of various SHM and condition-monitoring applications, offering a first screening of the sensor health prior to further analysis.

• 지적과 국토정보
• /
• 제46권2호
• /
• pp.297-312
• /
• 2016

현 정부는 미래 국가 경쟁을 이끌어 나갈 인재를 양성하고 학벌이 아닌 능력중심의 자격제도 개편을 통하여 자격과 산업현장을 일치시키려는 노력을 하고 있으며, 그 일환으로 과정평가형 자격제도 도입을 추진하고 있다. 과정평가형 자격제도는 국가직무능력표준(NCS)에 기반하여 일정 요건을 충족하는 교육 훈련과정을 이수하고 내,외부 평가를 거쳐 합격기준에 해당하는 경우, 국가기술자격을 부여하는 제도로 직업교육과 자격을 본격적으로 연계하기 위한 시도라고 할 수 있다. 지적분야의 NCS 및 학습모듈은 이미 특성화고등학교 및 전문대학에서 교육 훈련에 활용되고 있으나, 지적분야와 관련하여서는 아직까지 과정평가형 자격제도가 도입되지 않아 현행 국가기술자격검정을 통하여 자격을 취득할 수밖에 없는 실정이다. 본 연구는 과정평가형 자격제도를 면밀히 분석하고, 지적분야 과정평가형 자격제도 도입에 대한 의견을 수렴하기 위하여 설문조사를 실시하였으며, 과정평가형 자격제도 도입을 위한 NCS 평가모형을 제시하였다.