• Nuclear Engineering and Technology
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• 제39권2호
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• pp.95-102
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• 2007

The conceptual design of the MIT modular pebble bed reactor is described. This reactor plant is a 250 Mwth, 120 Mwe indirect cycle plant that is designed to be deployed in the near term using demonstrated helium system components. The primary system is a conventional pebble bed reactor with a dynamic central column with an outlet temperature of 900 C providing helium to an intermediate helium to helium heat exchanger (IHX). The outlet of the IHX is input to a three shaft horizontal Brayton Cycle power conversion system. The design constraint used in sizing the plant is based on a factory modularity principle which allows the plant to be assembled 'Lego' style instead of constructed piece by piece. This principle employs space frames which contain the power conversion system that permits the Lego-like modules to be shipped by truck or train to sites. This paper also describes the research that has been conducted at MIT since 1998 on fuel modeling, silver leakage from coated fuel particles, dynamic simulation, MCNP reactor physics modeling and air ingress analysis.

• 드라이브 ㆍ 컨트롤
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• 제17권1호
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• pp.1-12
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• 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.

• 대한기계학회논문집A
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• 제40권11호
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• pp.979-986
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• 2016

등속조인트의 일종인 트리포드 축은 동력전달용으로 고속열차의 KTX와 KTX-산천에 모두 적용되고 있으며, 동력대차에서 모터 감속장치(MRU)와 차축 감속장치(ARU)를 연결해 고속회전동력을 전달하는 핵심 요소이다. 축 방향의 미끄럼 운동이 가능한 트리포드 축은 열차 구동을 위한 토크를 전달하며, 동력전달 시스템에 과토크 발생 시 축의 퓨즈부가 절단되어 동력을 차단한다. 본 연구에서는 리니어 액추에이터를 이용한 대용량 비틀림 시험장치의 개발과 이를 이용한 트리포드 축의 정적 비틀림 강도와 피로수명을 확인하고자 하였다. 또한 구조해석을 통해 축의 취약부를 파악하고 비틀림 피로해석 결과와 실제 피로시험의 결과를 비교분석하여 비틀림 성능 개선을 위한 설계안을 제시하고자 하였다. 한편 트리포드 축의 피로에 따른 열화를 파악하기 위해 히스테리시스 곡선을 이용하였으며, 히스테리시스 곡선의 기울기 변화를 통해 피로고장 시점을 확인하였다.

• International Journal of Aeronautical and Space Sciences
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• 제9권1호
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• pp.100-110
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• 2008

It is not easy to monitor and identify all engine faults and conditions using conventional fault detection approaches like the GPA (Gas Path Analysis) method due to the nature and complexity of the faults. This study therefore focuses on a model based diagnostic method using Neural Network algorithms proposed for fault detection on a turbo shaft engine (PW 206C) selected as the power plant for a tilt rotor type unmanned aerial vehicle (Smart UAV). The model based diagnosis should be performed by a precise performance model. However component maps for the performance model were not provided by the engine manufacturer. Therefore they were generated by a new component map generation method, namely hybrid method using system identification and genetic algorithms that identifies inversely component characteristics from limited performance deck data provided by the engine manufacturer. Performance simulations at different operating conditions were performed on the PW206C turbo shaft engine using SIMULINK. In order to train the proposed BPNN (Back Propagation Neural Network), performance data sets obtained from performance analysis results using various implanted component degradations were used. The trained NN system could reasonably detect the faulted components including the fault pattern and quantity of the study engine at various operating conditions.

• 한국기계가공학회지
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• 제15권2호
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• pp.78-83
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• 2016

The development of an exclusive 8-axis multi-tasking machine to finish multiple cutting processes by a single piece of power equipment for securing the high-precision machining and high productivity of the series of shafts (a core part of the automotive powertrain that delivers engine power) is needed. The rigidity of the structure must be improved and the weight of the structure must be reduced to develop a multi-tasking machine with high precision and high productivity. In this paper, we perform a static structural analysis of the initial design of the multi-tasking machines and compare the results of the multi-tasking machines improved by the reinforced design and the results of the initial one. According to the results of the structural analysis, the rigidity of the reinforced machine was increased and the overall weight was decreased. Therefore, the productivity was increased.

• 소음진동
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• 제7권4호
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• pp.689-700
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• 1997

There are many difficulties in designing the engine structure properly due to the strong conflicts between NVH characteristics and the high performance, light weight and low product cost. Many feasible noise reduction techniques should be carefully incorporated to meet such stringent noise requirements. It is also required that the engine development be carried out by introducing concurrent engineering, in which the analysis and test database are usefully applied to the detail designs from the 1st stage. This paper reviews the significance of the noise characteristics of the structure elements in relation to the combustion pressure. The mechanisms of the crank shaft rumbling, which is the main source having the bad influence on the sound quality, are also explained. The influences of dynamic behavior of engine structure on its noise are investigated, followed by discussions on experimental results of the features necessary for the design of low noise engine concepts.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.78-83
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• 2009

In this study, computer applied engineering (CAE) techniques are fully used to conduct structural and dynamic analyses of a whole huge wind turbine system including composite blades, tower and nacelle. For this study, computational fluid dynamics (CFD) is used to predict aerodynamic loads of the rotating wind-turbine blade model. Multi-body dynamic structural analyses are conducted based on the non-linear finite element method (FEM) by using super-element method for composite laminates blade. Three-dimensional finite element model of a wind turbine system is constructed including power train(main shaft, gear box, coupling, generator), bedplate and tower. The results for multi-body dynamic simulations on the wind turbine's critical operating conditions are presented in detail.

• 소음진동
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• 제5권4호
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• pp.565-575
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• 1995

Gearboxes are often used in the petrochemical and electrical power plants to transmit mechanical power between two branches of a machinery train rotating at different speeds. When the gearboxes are connected with rotors supported by journal bearings, bearing loads vary in magnitude and direction with rotor speed and torque transmitted by the gearboxes. In this study, dynamic characteristics of the system which consists of gearboxes and a rotor supported by journal bearings are investigated analytically and experimentally by employing the polynomial transfer matrix method and modal analysis under different speeds and torque levels. Journal bearing loads due to the transmitted torque are claculated analytically and the stiffness and damping coefficient of the journal bearings are obtained using finite element method. Comparison of the analytical and experimental results shows that the cross coupled stiffness coefficients increase with increasing rotor speed, while the cross coupled damping coefficients decrease. This generates the oil whirl instability in the journal bearings. As the transmitted torque level goes up, the stiffness coefficients of the journal bearing and the first horizontal natural frequency increase. High levels of the transmitted torque produce high bearing stiffness since the contact loads of the mating gear teeth increase. The logarithmic decrement, which is a stability indicator, is shown to decrease with increasing speed and decreasing torque. Thus, at the low torque level, the system become unstable even at the low shaft speed.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.237-246
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• 2019

전기기계식 제동장치(EMB : Electro Mechanical Brake)는 자동차 및 철도차량의 차세대 제동장치로서 현재 연구가 활발히 진행되고 있다. 현재의 고속열차용 제동장치는 공압 실린더를 이용하여 제동 압부력을 발생시키나 전기기계식 제동장치 (EMB)에서는 전기 모터 및 기어와의 조합을 통하여 압부력을 발생시킨다. 본 연구에서는 고압부력 발생이 가능한 EMB 구동 메커니즘을 제안하고, 해당 메커니즘을 만드는 기구장치 중 핵심부품인 기어 및 샤프트 부품들에 대한 구조 및 진동해석을 수행하였다. 한편 모델에 대한 동적 진동해석 결과 압부력이 가해진 상태에서 외부가진이 주어졌을 때 부재의 최대 응력이 항복강도 이내임이 확인되었다. 또한, 구조해석 결과 모터샤프트의 축 직경을 최대한 크게하는 설계가 강도 상 유리함을 확인하였으며, 기어와 편심샤프트를 고정하는 볼트에서 큰 전단응력이 발생할 수 있음을 확인하였다. 한편 해석모델의 메커니즘을 재현할 수 있는 시험장치를 제작하여 가장 취약한 부위인 고정 볼트부의 변형률을 구동 토크가 가해진 상태에서 측정하였다. 변형률 측정결과는 해석결과와 오차가 10% 이내로서, 해석모델의 정확도를 검증할 수 있었다.

• 대한기계학회논문집A
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• 제38권1호
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• pp.89-99
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• 2014

본 논문에서는 유도탄 해치시스템의 스플라인 백래시에 의한 토크 외란에 대하여 실험을 통한 분석을 다룬다. 유도탄 해치시스템은 무거운 해치를 수직으로 상승시키기 위하여 스플라인과 기어열을 사용하고 있다. 해치의 회전축에 적용된 스플라인은 일반적으로 큰 동력전달을 위한 자동차의 구동 부품으로 사용된다. 스플라인은 각도 백래시를 갖고 있으며, 저크를 발생시킨다. 또한 해치 스플라인의 백래시는 해치의 흔들림 발생에 영향을 준다. 스플라인 백래시와 해치의 흔들림은 해치 회전각 및 해치의가속도를 측정함으로써 실험적으로 분석된다. 해치의 흔들림은 짧은 시간동안 육안으로 관찰되며, 회전각의 변화 및 해치 가속도에 의해 측정된다. 해치의 각 변화에 대한 변동형태 및 지속시간은 토크와 유사하며, 백래시에 의한 해치의 흔들림은 토크 외란을 발생시킴을 보여준다.